taxonID	type	description	language	source
71628244AE39FFFE5AD2A26765DFFE25.taxon	type_taxon	Type species. Ancorina cerebrum Schmidt, 1862 (by subsequent designation).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE39FFFB5AD2A11662C3FDD4.taxon	description	Figure 2 A – L, Table 1	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE39FFFB5AD2A11662C3FDD4.taxon	materials_examined	Material examined. SAMC-A 096923 (cross-reference TS 2475 & WSL-INV 84 (4 )), SAMC-A 096924 (cross-reference TS 2476 & WSL-INV 84 (5 )): Walters Shoal Seamount, Grid WSL 042, Station ALG 10974, coll. RV Algoa, (33 ° 11.2 ’ S; 43 ° 51.0 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.7 ’ E), 28 – 34 m depth, 02 June 2014.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE39FFFB5AD2A11662C3FDD4.taxon	description	Description (Fig. 2 A). Massive, amorphous form. Length 9.4 cm, width 5.6 cm and thickness 3.4 cm. Surface microhispid, prickly to the touch. A few oscules evident on the ridge (0.5 – 1 mm) and several (1 – 2 mm) on the underside of specimen SAMC-A 096924. Texture firm, dense and slightly rubbery. Barely compressible, not easily torn. Ectosome (~ 2 mm) present, not separable from the choanosome and yellow in life, white in preservative. Colour in life dark brown with yellowish tinge and darker brown, almost black ridges externally and paler brown internally. In preservative, dark brown externally and paler brown internally. Water retentive, leaving a brown exudate on tissue paper. Skeleton (Fig. 2 B). Choanosomal skeleton consists of radiating tracts of plagiotriaenes and oxeas. Tracts of large oxeas occur between the plagiotriaenes in mid- and deep choanosomal layers of the sponge. Oxyasters abundant and scattered throughout. Towards the surface, the tracts become denser and are entirely composed of plagiotriaenes with overlapping cladi. Ectosomal skeleton comprises a thick discernible layer with radiating plagiotriaene tracts that pierce the surface, through a dense (up to ~ 100 µm thick) layer of sanidasters. Spiculation (Table 1). Megascleres. Oxeas, smooth, straight to slightly bent, with no easily discernible size classes (continuous) and large size range: 1362 (728 – 2018) × 20 (6 – 37) µm, n = 20 (Fig. 2 C, D). Plagiotriaenes with short, stout cladi, rhabdome straight to slightly bent (Fig. 2 E, H), with juvenile forms also present (Fig. 2 F, G, H): I) Adult form, rhabdome 1710 (1550 – 2079) × 39 (33 – 47) µm, cladome 153 (130 – 179) µm, cladi 91 (75 – 117) µm, n = 20; II) juvenile form, rhabdome 792 (448 – 1037) × 15 (6 – 24) µm, cladome 49 (20 – 84) µm, cladi 22 (8 – 38) µm, n = 20. Microscleres. Oxyasters with ~ 10 rays, smooth or with hooked spines: 11 (9 – 15) µm, n = 20 (Fig. 2 I). Acanthoxyasters with 5 rays and hooked spines; some with vestigial actines with hooked spines, variable in form and spinosity: 19 (15 – 24) µm, n = 20 (Fig. 2 J, K). Sanidasters, acanthose, irregularly spined: 6 (5 – 7) µm, n = 20 (Fig. 2 L).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE39FFFB5AD2A11662C3FDD4.taxon	distribution	Distribution. Mozambique (Inhaca Island), Mbotyi (Eastern Cape), Walters Shoal Seamount	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE39FFFB5AD2A11662C3FDD4.taxon	discussion	Remarks. The present material conforms to Ancorina Schmidt, 1862 as diagnosed by a distinct cortex, the presence of oxeas and triaenes as megascleres and microscleres comprising sanidasters and euasters (Uriz 2002). Only 14 species are currently accepted within Ancorina according to the World Porifera Database (de Voogd et al. 2024), two of which are described from the Western Indian Ocean (WIO) & South Africa: Ancorina corticata Lévi, 1964 (Mozambique, WIO) and Ancorina nanosclera Van Soest, 2024 (South Africa). Ancorina nanosclera possesses anatriaenes; however, we did not find any anatriaenes in our specimens. These specimens closely resemble Ancorina corticata, as described from Mozambique, in terms of external morphology. They are dark brown to reddish in color and exhibit the following spiculation: oxeas measuring 2000 – 2400 × 50 µm, plagiotriaenes with a rhabdome size of 1400 × 70 µm and cladi measuring 130 – 150 × 50 µm, oxyasters at 15 – 20 µm, and sanidasters at 6 µm (see Table 1). This species has also been recorded from South Africa (Mbotyi, Eastern Cape) by Lévi (1967), with the following spicule measurements: oxeas measuring 1500 – 2400 × 50 – 65 µm, plagiotriaenes with a rhabdome size of 1000 – 1500 × 25 – 65 µm and cladi measuring 55 – 175 µm, oxyasters at 15 – 25 µm, and sanidasters at 7 µm (see Table 1). Ancorina corticata was also described by Samaai & Gibbons (2005) from the southwest coast of South Africa. The specimens from the west coast have much larger spicules, and the sanidasters appear significantly different from those found in our samples. The species discussed here is tentatively assigned to Ancorina corticata, based on the similarities outlined above. We have not examined or revised the type material although we observe some differences in spicule measurements: it is challenging to argue that this size variation is significant enough to warrant the description of a new species, especially since our knowledge of spicule size variation in A. corticata is limited. Table 1 presents spicule measurements from Lévi (1964, 1967) alongside those from our specimens, providing some context for the observed variation. We have not performed any SEM analysis on the type of A. corticata but Lévi's drawings (1964, 1967) suggest that the oxyasters likely have smaller spines like those found in our specimens.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE3CFFFB5AD2A18665DCFD02.taxon	type_taxon	Type species. Chelotropella sphaerica Lendenfeld, 1907 (type by monotypy).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE3CFFF55AD2A03F67D4FC68.taxon	description	urn: lsid: zoobank. org: act: D 058612 D-BC 8 B- 4 BD 0 - B 3 B 5 - 265 BBFDA 0953 Figure 3 A – K	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE3CFFF55AD2A03F67D4FC68.taxon	materials_examined	Material examined. Holotype. SAMC-A 096892 (cross-reference TS 2310 & WSL-INV 50 (1 )): Walters Shoal Seamount, Grid WSL 022, Station ALG 10954, coll. RV Algoa (33 ° 10.9 ’ S; 43 ° 48.6 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.2 ’ E), 72 – 170 m depth, 29 May 2014. Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE3CFFF55AD2A03F67D4FC68.taxon	description	Description (Fig. 3 A). Spherical form. Length 1.9 cm, diameter 1.5 cm and thickness 1.7 cm. Surface microhispid and prickly to the touch. One oscule (~ 3 mm) present at the top of the specimen. Thin cortex (~ 1 mm) present, separable from the choanosome. Texture firm and dense, not compressible. Colour in life dull dark brown externally, paler brown internally. In preservative, colour light brown. Slightly sticky exudate. Skeleton (Fig. 3 B, C, D). Choanosomal skeleton comprises thick, radial tracts of oxeas and triaenes (~ 200 – 400 µm across), forming two subdermal layers in the peripheral region. Calthrops arranged in a somewhat disorganized fashion, occasionally congregating in horizontal formations. Subectosomal skeleton comprises large subdermal cavities, triaenes orientated radially, with cladomes forming two layers parallel to the surface. Strongyloacanthasters concentrated in the ectosome (~ 300 – 500 µm), and scattered throughout the peripheral region, including around subdermal spaces. Spiculation. Megascleres. Oxeas, smooth, straight to slightly curved, distally fusiform: 2134 (1092 – 3016) × 20 (11 – 31) µm, n = 20 (Fig. 3 E). Dichotriaenes (Fig. 3 F, G), in two size classes: I) rhabdome 2812 (2615 – 3078) × 51 (49 – 52) µm, cladome 501 (361 – 573) µm, stout protoclads 135 (111 – 154) µm, long deuteroclads terminating in somewhat blunt points 169 (89 – 222) µm, n = 3; II) rhabdome 1169 (786 – 1520) × 20 (24 – 34) µm, cladome 291 (254 – 334) µm, stout protoclads 118 (103 – 139) µm, short deuteroclads terminating in somewhat sharp points 40 (21 – 50) µm, n = 20. Anatriaenes (Fig. 3 H): 1153 (807 – 1458) × 9 (8 – 11) µm, with cladome 74 (53 – 89) µm, n = 20. Plagiotriaenes (Fig. 3 I), short-shafted, rare: 302 (111 – 694) × 16 (10 – 22) µm, with cladome 145 (63 – 260) µm, and cladi 77 (35 – 136) µm, n = 12. Calthrops (Fig. 3 J, K), regular in shape, found in two size classes (ray): I) 480 (404 – 595) × 52 (43 – 61) µm, n = 20; II) 197 (134 – 259) × 24 (15 – 34) µm, n = 20. Microscleres. Strongyloacanthasters (Fig. 3 L) with ~ 10 terminally hook-spined rays: 19 (14 – 23) µm, n = 20.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE3CFFF55AD2A03F67D4FC68.taxon	etymology	Etymology. The name ‘ alexrogersi’ was given in honour of Prof. Alex D. Rogers, for his pioneering expeditions all over the world as part of the Ocean Census programme to discover new species.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE3CFFF55AD2A03F67D4FC68.taxon	discussion	Remarks. The present material conforms to Chelotropella Lendenfeld, 1907 as diagnosed by the presence of calthrops, oxeas and peripheral dichotriaenes that form a radial skeleton, and two subdermal layers in the peripheral region (Van Soest & Hooper 2002). Erected by Lendenfeld in 1907 for a single species, this genus comprises two described species to date: Chelotropella sphaerica Lendenfeld, 1907 and Chelotropella neocaledonica Lévi & Lévi, 1983, of which only the former occurs in the Indian Ocean, with the latter found in New Caledonia. Although similar to C. sphaerica with regards to morphology (spherical sponge of ~ 1.8 cm with granular surface as described by Lendenfeld in 1907), the spicule component of the present material differs. The material in this study has megascleres that are smaller and narrower than those described by Lendenfeld (1907) (oxeas: 3600 – 5600 × 50 – 80 µm; dichotriaenes: rhabdome 2800 – 4400 × 100 – 440 µm, cladome 650 – 1300 µm, clades 130 – 170 µm; calthrops: I) 700 – 1050 × 85 – 120 µm, II) 170 – 700 × 20 – 85 µm), with his species also lacking anatriaenes and plagiotriaenes (although intermediate forms between calthrops and triaenes are noted), but including the presence of various euaster morphologies. Pulitzer-Finali (1993) recorded C. sphaerica from Kenya, also with various euaster morphologies, but with megasclere size ranges more in accordance with the present material (oxeas: 3500 – 4500 × 27 – 45 µm; dichotriaenes: rhabdome 2400 × 80 µm, cladome 1600 µm, protoclads 270 µm, deuteroclads 500 µm; calthrops: 300 – 760 µm). Pulitzer-Finali (1993) also found long anatriaenes (rhabdome 4000 × 20 – 36 µm, cladome 150 – 170 µm), which led Van Soest & Hooper (2002) to suggest that Pulitzer-Finali’s specimen may be a new species distinct from C. sphaerica. Thus, due to the presence of anatriaenes (in a much smaller size range than recorded by Pulitzer-Finali in 1993) and plagiotriaenes, as well as the lack of diverse euaster morphologies (only one type found), the present material constitutes a new species.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE32FFF55AD2A7456578FB4F.taxon	type_taxon	Type species. Penares helleri (Schmidt, 1864) (by monotypy).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE32FFF15AD2A7F8650CF954.taxon	description	urn: lsid: zoobank. org: act: 58 A 654 F 1 - 3650 - 4 C 30 - A 957 - 2 FAF 574 DE 4 FB Figure 4 A – J, Table 2	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE32FFF15AD2A7F8650CF954.taxon	materials_examined	Material examined. Holotype. SAMC-A 096918 (cross-reference TS 2447 & WSL-INV 74 (13 )): Walters Shoal Seamount, Grid WSL 024, Station ALG 10956, coll. RV Algoa, (33 ° 08.8 ’ S; 43 ° 49.1 ’ E) - (33 ° 09.0 ’ S; 43 ° 50.5 ’ E), 103 – 348 m depth, 29 May 2014. Paratypes. SAMC-A 096887 (cross-reference TS 2300 & WSL-INV 58), SAMC-A 096890 (cross-reference TS 2307 & WSL-INV 57 (2 )): Walters Shoal Seamount, Grid WSL 022, Station ALG 10954, coll. RV Algoa, (33 ° 10.9 ’ S; 43 ° 48.6 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.2 ’ E), 72 – 170 m depth, 29 May 2014. SAMC-A 096917 (cross-reference TS 2445 & WSL-INV 74 (11 )): Walters Shoal Seamount, Grid WSL 024, Station ALG 10956, coll. RV Algoa, (33 ° 08.8 ’ S; 43 ° 49.1 ’ E) - (33 ° 09.0 ’ S; 43 ° 50.5 ’ E), 103 – 348 m depth, 29 May 2014. Additional material. TS 2314 (WSL-INV 51): Walters Shoal Seamount, Grid WSL 022, Station ALG 10954, coll. RV Algoa, (33 ° 10.9 ’ S; 43 ° 48.6 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.2 ’ E), 72 – 170 m depth, 29 May 2014. TS 2446 (WSL-INV 74 (12 )), TS 2451 (WSL-INV 74 (17 )), TS 2454 (WSL-INV 74 (20 )), TS 2548 (WSL-INV 74 (30 )), TS 2555 (WSL-INV 74 (37 )): Walters Shoal Seamount, Grid WSL 024, Station ALG 10956, coll. RV Algoa, (33 ° 08.8 ’ S; 43 ° 49.1 ’ E) - (33 ° 09.0 ’ S; 43 ° 50.5 ’ E), 103 – 348 m depth, 29 May 2014. Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE32FFF15AD2A7F8650CF954.taxon	description	Description (Fig. 4 A). Thickly encrusting form. Length 1.5 cm, width 1.7 cm and thickness 0.3 cm. Surface undulating but smooth with oscules (<1 mm) scattered randomly over the surface. Thin cortex (<1 mm) present, separable from the choanosome. Texture firm, tough, dense and leathery. Specimen not compressible, easily torn. Colour in life dull orange-brown externally and internally, pale olive green in preservative. Skeleton. Confused choanosomal skeleton, comprising of oxeas and microxeas arranged in a disorderly fashion (spicules distributed randomly), showing little tendency to form tracts (Fig. 4 B). Larger oxeas sometimes aggregating in loose (somewhat radial) slanting bundles (~ 60 – 140 µm across). Dichotriaenes form subdermal skeleton, with cladome at surface and rhabdome inwards. Oxyasters abundant and scattered throughout. Ectosomal skeleton comprised of small oxeas, lying tangentially over dichotriaene clads, forming dense dermal crust ~ 200 – 300 µm thick (Fig. 4 C). Spiculation (Table 2). Megascleres. Oxeas, slightly curved, in three size classes: I) Large, 801 (703 – 999) × 27 (21 – 37) µm, n = 20 (Fig. 4 D); II) medium, 393 (318 – 546) × 19 (15 – 22) µm, n = 25 (Fig. 4 E); III) small, 143 (118 – 186) × 9 (7 – 12) µm, n = 20 (Fig. 4 F). Dichotriaenes (Fig. 4 G, H), with short rhabdomes, in two size classes: I) rhabdome not seen (~ half the size of the cladome) [TS 2307 rhabdome, 134 (49 – 201) × 29 (20 – 39) µm, n = 6)], cladome 485 (381 – 579) µm, stout protoclads 101 (68 – 124) × 36 (28 – 49) µm, deuteroclads, often irregular at tips 141 (116 – 178) × 28 (20 – 39) µm, n = 20; II) rhabdome not seen (~ half the size of the cladome) [TS 2307 rhabdome, 89 (40 – 133) × 24 (14 – 31) µm, n = 7)], cladome 338 (226 – 481) µm, thin protoclads 90 (75 – 108) × 20 (14 – 27) µm, deuteroclads terminating in sharp points 67 (28 – 123) × 14 (7 – 19) µm, n = 20. Microscleres. Microxeas (Fig. 4 I), curved: 77 (63 – 99) × 6 (5 – 7) µm, n = 20. Acanthoxyasters with ~ 16 slender rays, hooked spines and sharply pointed tips: 9 (8 – 12) µm, n = 20 (Fig. 4 J). Substratum, depth range and ecology. Ten specimens found on rocky substrata in two sleds, one consisting of predominantly bivalves and sponges, the other of biogenic debris and hydrozoans. Depth range: 72 – 348 m.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE32FFF15AD2A7F8650CF954.taxon	etymology	Etymology. Named for the type locality and known distribution of this species, Walters Shoal Seamount.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE32FFF15AD2A7F8650CF954.taxon	discussion	Remarks. Sponges in the genus Penares are typically irregularly massive, cream, grey or black in live colouration, and are characterised by a thin cortex comprised of smooth microxeas or microrhabds, and short-shafted plagio-, dicho- or orthotriaenes (Sim-Smith & Kelly 2019). The genus Penares currently includes 44 valid species (de Voodg et al. 2024), which are found in temperate and tropical waters of the world, from the intertidal to depths of more than 1000 m (Sim-Smith & Kelly 2019). Only three species have been described from temperate southern Africa, the WIO, and the West and South Indian Shelf Provinces. Penares orthotriaena Burton, 1931 was recorded from the Natal and Delagoa ecoregions, whilst Penares schulzei (Dendy, 1905) and Penares intermedius (Dendy, 1905) were described from South India and Sri Lanka. Penares schulzei (Dendy, 1905) has been recorded in New Caledonia and New Zealand by Sim-Smith & Kelly (2019), expanding its range to the tropical southwestern Pacific and northern New Zealand ecoregion. These species will be compared with the present material. Penares orthotriaena Burton, 1931 described from the mouth of the uThukela and Umvoti Rivers (Natal ecoregion) at a depth of 64 m, is a massive sponge possessing orthotriaenes with a straight rhabdome, biangulate microstrongyla and tylasters (see Fig. 1 in Burton (1931 )). Lévi (1964) recorded the species from Mozambique. However, Lévi's sample (see Fig. 7 in Lévi (1964 )) lacks orthotriaenes, biangulate microstrongyla, and tylasters present in the holotype. Lévi's sample is more similar to the undescribed new species described here, based on the spicule complement in Fig. 7, although Lévi (1964) provides little information. Penares intermedius (Dendy, 1905) collected in waters 182 m deep, 12 miles off the coast of Galle, Sri Lanka (Dendy 1905), is an irregularly branched and shortly stalked nodose sponge, spreading more or less horizontally, and rounded at the extremities. Pulitzer-Finali (1993) identified a specimen from North Kenya Banks, Kenya (110 m) as P. intermedius, noting the presence of short-shafted triaenes, large oxeas and smooth oxyasters similar to those observed in the holotype. Pulitzer-Finali (1993) found that smaller oxeas had a continuous graduation between the smaller oxeas, with a size range from 75 – 410 µm. Dendy (1905) also said that, “ varying very much in size; averaging, say, about 0.18 millim. by 0.01 millim, but ranging from about a third of these dimensions through intermediate sizes to the large forms. Thomas (1984) identified a specimen collected from Sri Lanka as Penares intermedius (Dendy, 1905). Thomas noted “ minutely spined or not ” oxyasters in his specimen. Dendy (1905) and Pulitzer-Finali (1993) did not mention minutely spined oxyasters, which may be due to the fact that the spines may only be visible with a scanning electron microscope. This could explains the (slightly larger) ‘ smooth’ oxyasters given in the original description of P. intermedius (Dendy, 1905) when viewed through a light microscope. However, we cannot confirm this, as we have not studied the holotype of P. intermedius. The comparative spicule dimensions for the specimens of Dendy (1905), Pulitzer-Finali (1993) and Thomas (1984) are as follows: Penares intermedius (Dendy, 1905) originally described as Plakinastrella intermedia (oxeas: I) 1200 × 37 µm, II) 180 x 10 µm; dichotriaenes: rhabdome 370 × 55 µm, with protoclads 92 × 55 µm; oxyasters: 25 µm) and further records of this species by Pulitzer-Finali (1993) (oxeas: I) 1000 – 1500 x 33 – 62 µm, II) 75 – 410 × 5.5 – 22 µm; dichotriaenes: rhabdome 190 µm, protoclads 95 µm, deuteroclads 160 µm; Oxyasters: 12 – 23 µm) and Thomas (1984) (oxeas: I) 790 x 30 µm, II) 190 × 6 – 12 µm; dichotriaenes: protoclads 80 × 50 µm, deuteroclads 280 × 5 µm; oxyasters: 18 µm). Although Dendy (1905) only described one size class of dichotriaenes for P. intermedius (Table 2), he does make note of ‘ slenderer’ forms which he suggests are not fully developed. In addition, while providing two size classes of oxeas, he notes a large size range (Table 2). Our specimen has a clear size separation between the oxeas and has heavily spined oxyasters that are much smaller than those of P. intermedius (Table 2). The thinly encrusting form, spicule dimensions and spined oxyasters of the new species described here differ substantially from the holotype of P. intermedius (Plate I, Fig. 4; Plate II, Fig. 2 in Dendy (1905 )) and the Kenyan specimen (Pulitzer-Finali 1993). Dendy (1905) reported a second species, Penares schulzei (Dendy, 1905), off the coast of Galle, Sri Lanka, in the same locality and station as Penares intermedius. Burton (1959) proposed that Plakinastrella (now Penares) schulzei (Dendy, 1905) is conspecific with P. intermedius, based on similarities in the figures drawn (see Plate II, Figs. 2 & 3 in Dendy (1905 )) and a re-examination of the holotypes. This suggestion was accepted by Thomas (1984), but ignored by Pulitzer-Finali (1993). Burton (1959) recorded the species from Zanzibar at depths ranging from 75 to 165 m. Lévi & Lévi (1983) and Sim-Smith & Kelly (2019) regarded Penares schulzei as a valid species. This is based on specimens collected from New Caledonia and New Zealand, respectively. Penares schulzei and P. intermedius continue to be identified separately in the World Porifera Database (de Voogd et al. 2024). The specimen described by Lévi & Lévi (1983) had smooth oxyasters with 6 – 8 actines and a diameter of 20 – 30 µm. The holotype has short-shafted dichotriaenes (Dendy, 1905 Plate II, Fig. 3) resembling calthrops with a total diameter of 680 µm. Similar to Penares intermedius, Lévi & Lévi (1983) may not have been able to determine if the oxyasters are lightly spined because they observed the spicules under a light microscope. However, we cannot confirm this, as we have not studied the holotype of P. schulzei. The New Zealand specimen (NIWA 75616) (Sim-Smith & Kelly 2019) has spined oxyasters and a noticeable size separation between the oxeas and microxeas, which differs from the holotype of Penares schulzei. Thomas (1984) found spined oxyasters in a specimen that he identified as P. intermedius. The NIWA 75616 specimen appears to include smaller oxyasters (size range 12 – 29 µm), notwithstanding Sim-Smith and Kelly's (2019) statement of only one size group. Smaller oxyasters are thus present in the New Zealand specimens (NIWA 75616) and the Chatham Rise specimen collected by Bergquist (1961) (see Table 2 in Sim-Smith & Kelly 2019). The dichotriaenes in New Zealand specimens are also larger than those in New Caledonia specimen and smaller than in the holotype. Comparing the spicule measurements of P. intermedius with those of P. schulzei, several differences in spicule sizes are evident between the two species (Table 2): dichotriaene cladomes measure 370 µm for P. intermedius and 680 µm for P. schulzei; microxeas measure 180 µm for P. intermedius and 350 µm for P. schulzei; and oxyasters have a ray length of 25 µm for P. intermedius compared to a total diameter of 20 µm for P. schulzei. Based on these differences in spicule size, we do not agree with Burton's (1959) assertion that P. schulzei (Dendy, 1905) is conspecific with P. intermedius. Recent findings further indicate that cosmopolitanism is not a common trait in sponges, and that species with distributions spanning multiple oceans are often complexes of cryptic species with similar morphological characters (Boury-Esnault et al. 1999; Xavier et al. 2010; de Paula et al. 2012; Mote et al. 2019). In this example, as in many others, molecular taxonomy, in addition to morphology, can assist in distinguishing Penares schulzei and P. intermedius, as well as separate cryptic species (Bickford et al. 2007; Xavier et al. 2010; Escobar et al. 2012; Leal et al. 2016; Shaffer et al. 2019). The present material is not identical to the holotype descriptions of Penares schulzei, P. intermedius, and P. orthotriaena and is thus considered distinct and new to science.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE36FFF15AD2A49E65A7F81A.taxon	type_taxon	Type species. Tethya aurantium (Pallas, 1766) (type by subsequent designation).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE37FFED5AD2A39F633CFDF0.taxon	description	urn: lsid: zoobank. org: act: 28 C 01 F 6 C-DBAF- 4 D 85 - A 164 - 43 A 33 F 9 B 2 AD 9 Figure 5 A – G, Table 3	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE37FFED5AD2A39F633CFDF0.taxon	materials_examined	Material examined. Holotype. SAMC-A 096908 (cross-reference TS 2358 & WSL-INV 94 (30 )): Walters Shoal Seamount, Grid WSL 044, Station ALG 10976, coll. RV Algoa, (33 ° 14.0 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.7 ’ S; 43 ° 55.6 ’ E), 25 – 28 m depth, 02 June 2014. Paratypes. SAMC-A 096893 (cross-reference TS 2311 & WSL-INV 50 (2 )), SAMC- A 096896 (cross-reference TS 2327 & WSL-INV 40): Walters Shoal Seamount, Grid WSL 022, Station ALG 10954, coll. RV Algoa, (33 ° 10.9 ’ S; 43 ° 48.6 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.2 ’ E), 72 – 170 m depth, 29 May 2014. SAMC-A 096899 (cross-reference TS 2337 & WSL-INV 94 (8 )): Walters Shoal Seamount, Grid WSL 044, Station ALG 10976, coll. RV Algoa, (33 ° 14.0 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.7 ’ S; 43 ° 55.6 ’ E), 25 – 28 m depth, 02 June 2014. Additional material. TS 2349 (WSL-INV 94 (21 )), TS 2352 (WSLINV 94 (24 )): Walters Shoal Seamount, Grid WSL 044, Station ALG 10976, coll. RV Algoa, (33 ° 14.0 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.7 ’ S; 43 ° 55.6 ’ E), 25 – 28 m depth, 02 June 2014. TS 2362 (WSL-INV 75 (3 )), TS 2363 (WSL-INV 75 (4 )), TS 2376 (WSL-INV 75 (17 )): Walters Shoal Seamount, coll. RV Algoa, (33 ° 11.2 ' S; 43 ° 50.7 ' E), 29 m depth, 30 May 2014. TS 2420 (WSL-INV 24 (a )): Walters Shoal Seamount, Grid WSL 021, Station ALG 10953, coll. RV Algoa, (33 ° 11.0 ’ S; 43 ° 53.9 ’ E) - (33 ° 11.0 ’ S; 43 ° 52.9 ’ E), 43 – 53 m depth, 29 May 2014. TS 2430 (WSL-INV 119 (4 )): Walters Shoal Seamount, coll. RV Algoa, (33 ° 11.6 ' S; 43 ° 50.5 ' E), 39 m depth, 05 June 2014. TS 2474 (WSL-INV 84 (3 )), TS 2489 (WSLINV 84 (18 )), TS 2493 (WSL-INV 84 (22 )), TS 2496 (WSL-INV 84 (25 )), TS 2498 (WSLINV 84 (27 )): Walters Shoal Seamount, Grid WSL 042, Station ALG 10974, coll. RV Algoa, (33 ° 11.2 ’ S; 43 ° 51.0 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.7 ’ E), 28 – 34 m depth, 02 June 2014. TS 2538 (WSL-INV 102 (4 )): Walters Shoal Seamount, Grid WSL 045, Station ALG 10977, coll. RV Algoa, (33 ° 13.8 ’ S; 43 ° 56.1 ’ E) - (33 ° 14.2 ’ S; 43 ° 55.9 ’ E), 80 m depth, 02 June 2014. Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE37FFED5AD2A39F633CFDF0.taxon	description	Description (Fig. 5 A). Spherical to semi-spherical form. Length 1.6 cm and thickness 1.4 cm. Surface rough and fuzzy, but undulating and smooth in a couple of specimens. In other specimens, one (rarely two) oscules present on apex (~ 1 mm). Well-developed ectosome, ~ 1 – 2 mm thick, which is distinct but not separable from the choanosome. Texture tough, firm and dense. Not compressible, nor easily torn. Colour in life pale beige (with brown tinge) externally, olive green internally, with a white centre. In preservative, pale beige. Ectosome colour in life, and in preservative, white. Slightly sticky exudate present in a few specimens. Skeleton (Fig. 5 B). Choanosomal skeleton radial, comprising compact anisostrongyloxea and (aniso) strongyle (rare) tracts (~ 200 µm across) radiating from the centre of the sponge, often penetrating the ectosome as expanding dermal brushes, with megascleres piercing the sponge surface. Somewhat confused interstitial anisostrongyloxeas fill the space around the main megasclere bundles. Microscleres are common in the inner choanosome between the tracts. Thick, discernible ectosome (> 1000 µm) comprised of small radial bouquets (~ 400 – 600 µm across) of megascleres embedded within this region, which pierce the sponge surface. Megasters (represented by spherasters) and micrasters are densely packed in ectosome, somewhat entering the upper regions of the choanosome, with the former decreasing in size from the sponge surface, inwards. Spiculation (Table 3). Megascleres. Primary and auxiliary anisostrongyloxeas, smooth, straight, thickest centrally, with reduced, somewhat elongate apices, often distally hastate, with no easily discernible size classes (continuous) and large size range: 639 (293 – 1280) × 11 (6 – 23) µm, n = 20 (Fig. 5 C). Strongyles to anisostrongyles, relatively rare, smooth, straight, thickest centrally, often fusiform, with no easily discernible size class: 1020 (596 – 1249) × 17 (9 – 25) µm, n = 20 (Fig. 5 D). Microscleres. Megasters - spherasters with ~ 15 rays: 41 (21 – 56) µm, n = 20 (Fig. 5 E). Micrasters - tylasters with ~ 11 terminally spined rays: 13 (10 – 15) µm, n = 20 (Fig. 5 F); Spheroxyasters with ~ 8 rays: 6 (5 – 8) µm, n = 20 (Fig. 5 G).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE37FFED5AD2A39F633CFDF0.taxon	etymology	Etymology. The name ‘ muricyi’ was given in honour of Dr Guilherme Muricy for his important contribution to the taxonomy, ecology and diversity of Brazilian sponges.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE37FFED5AD2A39F633CFDF0.taxon	discussion	Remarks. The present material conforms well to Tethya Lamarck, 1815, as diagnosed by a spherical form, well-developed, distinct ectosome and main skeleton formed by radiating strongyloxea bundles (Sarà 2002). It is not conspecific with the nine species of Tethya that have been recorded from the WIO and South Africa: Tethya globostellata Lendenfeld, 1897; Tethya japonica Sollas, 1888; Tethya magna Kirkpatrick, 1903; Tethya parvistella (Baer, 1906); Tethya peracuta (Topsent, 1918); Tethya robusta (Bowerbank, 1873); Tethya samaaii Ribeiro & Muricy, 2011; Tethya seychellensis (Wright, 1881) and Tethya stellagrandis (Dendy, 1916) (see Comparative measurements Table 3; de Voogd et al. 2024). Tethya globostellata Lendenfeld, 1897 (anisostrongyloxeas: 1000 – 2100 × 24 – 32 µm; styles: 400 – 500 × 14 – 16 µm; amphistrongyles: 1000 – 1500 × 33 µm; oxyasters: 60 – 100 µm; strongylasters: 9 – 12 µm) and T. parvistella (Baer, 1906) (anisostrongyloxeas: 718 – 1342 × 3 – 18 µm; amphistrongyles: 841 – 1100 × 14 – 18 µm; spherasters: 33 – 59 µm; tylasters: I) 7 µm, II) 11 µm) somewhat resembles the present material. However, Tethya japonica and Tethya parvistella lack spheroxyasters, whereas Tethya globostellata, Tethya magna Kirkpatrick, 1903, Tethya peracuta (Topsent, 1918), Tethya robusta, Tethya samaaii, Tethya seychellensis and Tethya stellagrandis have medium to large spheroxyasters, unlike the small spheroxyasters found in Tethya muricyi sp. nov. (Table 3).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2AFFED5AD2A1E2630BFCAA.taxon	type_taxon	Type species. Agelas dispar Duchassaing & Michelotti, 1864: 76 (by subsequent designation; Burton & Rao, 1932: 355).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2AFFEE5AD2A08567A1FAD8.taxon	description	urn: lsid: zoobank. org: act: C 0 DAE 477 - A 890 - 47 AC- 8793 - DAE 26685 D 270 Figure 6 A – F, Table 4	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2AFFEE5AD2A08567A1FAD8.taxon	materials_examined	Material examined. Holotype. SAMC-A 096894 (cross-reference TS 2313 & WSL-INV 48): Walters Shoal Seamount, Grid WSL 022, Station ALG 10954, coll. RV Algoa, (33 ° 10.9 ’ S; 43 ° 48.6 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.2 ’ E), 72 – 170 m depth, 29 May 2014. Paratypes. SAMC-A 096891 (cross-reference TS 2309 & WSL-INV 47), SAMC-A 096895 (cross-reference TS 2317 & WSL-INV 46 (2 )): Walters Shoal Seamount, Grid WSL 022, Station ALG 10954, coll. RV Algoa, (33 ° 10.9 ’ S; 43 ° 48.6 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.2 ’ E), 72 – 170 m depth, 29 May 2014. SAMC-A 096916 (cross-reference TS 2441 & WSL-INV 74 (7 )): Walters Shoal Seamount, Grid WSL 024, Station ALG 10956, coll. RV Algoa, (33 ° 08.8 ’ S; 43 ° 49.1 ’ E) - (33 ° 09.0 ’ S; 43 ° 50.5 ’ E), 103 – 348 m depth, 29 May 2014. Additional material. TS 2443 (WSL-INV 74 (9 )), TS 2452 (WSL-INV 74 (18 )), TS 2455 (WSL-INV 74 (21 )), TS 2456 (WSL-INV 74 (22 )), TS 2549 (WSL-INV 74 (31 )): Walters Shoal Seamount, Grid WSL 024, Station ALG 10956, coll. RV Algoa, (33 ° 08.8 ’ S; 43 ° 49.1 ’ E) - (33 ° 09.0 ’ S; 43 ° 50.5 ’ E), 103 – 348 m depth, 29 May 2014. Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2AFFEE5AD2A08567A1FAD8.taxon	description	Description (Fig. 6 A). Repent-ramose form, which binds together with biogenic debris, creating a conglomerate (not shown). Length 6.5 cm, diameter 1.3 cm and thickness 0.7 cm. Surface rough and fuzzy, with small, randomly scattered oscules, ranging from <1 mm – 1 mm in diameter. Consistency and texture is soft and spongy, compressible and not easily torn. Colour in life brownish orange, pale orange in preservative. Skeleton (Fig. 6 B, C, D). Choanosomal skeleton consists of a uniform network of spongin fibres, 30 – 60 μm in diameter, echinated by verticillate acanthostyles, with blunt (head) ends embedded in the fibre. There are no clear distinction between primary and secondary fibres. These fibres are also rarely cored with verticillate acanthostyles (embedded lengthwise in fibre). Ascending fibres usually echinated while transverse fibres are not, but this is not always the case. Interconnecting transverse fibres are often uncored, and form irregular meshes of 30 – 100 µm in diameter. Spongin is sparsely scattered through the mesohyl. No ectosomal specialisation. Spiculation (Table 4). Megascleres. Verticillate acanthostyles in two size classes: I) 191 (152 – 245) × 8 (6 – 11) µm, n = 20, with 15 – 22 whorls of spines (Fig. 6 E); II) 119 (90 – 148) × 5 (3 – 6) µm, n = 20, with 12 – 17 whorls of spines (Fig. 6 F). Microscleres. Absent.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2AFFEE5AD2A08567A1FAD8.taxon	etymology	Etymology. The name ‘ kellyae’ was given in honour of Dr Michelle Kelly, a marine biologist and sponge taxonomist at NIWA, New Zealand for her invaluable contributions to the taxonomy, ecology and diversity of sponges from not only New Zealand and the Indo-Pacific, but also to South Africa and the WIO.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2AFFEE5AD2A08567A1FAD8.taxon	discussion	Remarks. To date, six Agelas species are described from the Western Indian Ocean. These are A. bispiculata Vacelet, Vasseur & Lévi, 1976, A. ceylonica Dendy, 1905, A. marmarica Levi, 1958, A. mauritiana (Carter, 1883), A. oxeata Samaai, Pillay & Janson, 2019 and A. sansibarica Perino & Pronzato, 2016 (de Voogd et al. 2024). Agelas sansibarica contains three types of megasclere spicules: acanthostyles, acanthoxeas, and acanthostrongyles (Manconi et al. 2016). Agelas oxeata contains two types of megasclere spicules: acanthostyles and acanthoxeas (Lévi 1961, Samaai et al. 2019). Agelas ceylonica, which was described by Dendy (1905) from the Gulf of Mannar consist of ‘ a few slender, anastomosing, sub-cylindrical branches, arising from an irregular, proliferous basal crust attached to a calcareous nodule’. Dendy (1905) describes this species as having verticillate spined styles of approximately 240 × 20 µm, while Lévi (1961) describes specimens from the Seychelles as having two classes of ‘ acanthostyles’ (I) 80 – 275 × 5 – 15 µm, with 16 – 21 whorls; II) 100 – 300 × 6 – 15 µm, with 13 – 23 whorls) (see Table 4). Thomas (1981) analysed specimens he identified as Agelas ceylonica from Mahe Island, Seychelles, and found smooth styles, a spicule type not mentioned in Dendy’s original 1905 description (Dendy 1905). Pereira and Raghunathan (2020) also observed smooth styles with plain whorls in a specimen assigned to Agelas ceylonica sensu Thomas, 1981 collected from Andaman and Nicobar Islands, India. The external morphology and presence of smooth styles indicate that the specimens studied by Thomas (1981) and Pereira & Raghunathan (2020) are distinct from Agelas ceylonica. Further research based on both morphology and molecular data is needed to clarify this species complex. The descriptions of the other species in this region: Agelas bispiculata Vacelet, Vasseur & Lévi, 1976 (verticillate acanthostyles: I) 320 – 400 × 14 – 17 µm, with 20 whorls; II) 55 – 120 × 6 – 10 µm, with 11 – 15 whorls), Agelas marmarica Lévi, 1958 (verticillate acanthostyles: 230 × 10 µm, with 19 – 21 whorls) and Agelas mauritiana (Carter, 1883) (verticillate acanthostyles according to Lévi (1961): 150 – 160 × 8 – 12 µm, with 16 – 20 whorls; Manconi et al. (2016): 132 µm, with 15 – 18 whorls) also seem to be quite similar, especially with regards to morphology (Table 4). However, Agelas kellyae Payne, Samaai & Gibbons sp. nov. differs from the above due to the presence of very distinct, elongated spines on the smaller verticillate acanthostyles of this species, which also cover the head of the spicule, presence of smaller categories of acanthostyles and absence of smooth styles as found in A. ceylonica sensu Thomas, 1981 (ZSI / ANRC – 20437) or acanthoxeas as in Agelas oxeata. The presence of smooth styles with plain whorls was not mentioned in the original description A. ceylonica by Dendy (1905) but found by Thomas (1981) when analysing additional specimens collected from Mahe Island. As we did not find styles with plain whorls or acanthoxeas, the specimen reported here from Walters Shoal constitutes a new species, Agelas kellyae Payne, Samaai & Gibbons sp. nov.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE29FFEE5AD2A50A62E4F9B2.taxon	type_taxon	Type species. Ptilocaulis walpersii (Duchassaing & Michelotti, 1864) (by subsequent designation).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE29FFE95AD2A5AA6369FB48.taxon	description	urn: lsid: zoobank. org: act: 083 B 370 F-B 75 C- 4244 - 9 DAA-B 6388 C 0 DC 22 C Figure 7 A – E, Table 5	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE29FFE95AD2A5AA6369FB48.taxon	materials_examined	Material examined. Holotype. SAMC-A 096915 (cross-reference TS 2440 & WSL-INV 74 (6 )): Walters Shoal Seamount, Grid WSL 024, Station ALG 10956, coll. RV Algoa, (33 ° 08.8 ’ S; 43 ° 49.1 ’ E) - (33 ° 09.0 ’ S; 43 ° 50.5 ’ E), 103 – 348 m depth, 29 May 2014. Paratypes. SAMC-A 096919 (cross-reference TS 2448 & WSL-INV 74 (14 )), SAMC-A 097071 (cross-reference TS 2546 & WSL-INV 74 (28 )), SAMC-A 096928 (cross-reference TS 2570 & WSL-INV 74 (52 )): Walters Shoal Seamount, Grid WSL 024, Station ALG 10956, coll. RV Algoa, (33 ° 08.8 ’ S; 43 ° 49.1 ’ E) - (33 ° 09.0 ’ S; 43 ° 50.5 ’ E), 103 – 348 m depth, 29 May 2014. SAMC-A 096920 (cross-reference TS 2458 & WSL-INV 114 (1 )): Walters Shoal Seamount, Grid WSL 047, Station ALG 10979, coll. RV Algoa, (33 ° 09.7 ’ S; 43 ° 58.4 ’ E) - (33 ° 09.8 ’ S; 43 ° 57.0 ’ E), 317 – 512 m depth, 03 June 2014. Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE29FFE95AD2A5AA6369FB48.taxon	description	Description (Fig. 7 A). Erect, dichotomously branching form, with few scopiform flattened processes. Length 3.1 cm, width 3.2 cm and thickness 0.4 cm. Surface irregular and finely hispid (due to protruding spicules) with small circular oscules (<1 mm) scattered throughout. Spicules protruding <1 mm from the surface, thus fuzzy to the touch. Texture soft and spongy, compressible and easily torn. Colour in life yellow / ochre, white in preservative. Skeleton (Fig. 7 B, C, D). Choanosomal skeleton consists of a dense interwoven mass of sinuous styles cored in fascicles. All axial spicules are disposed longitudinally in a plumose fashion. Spicule tracts are sometimes definable for only a very short distance before becoming obscured in the general mass. The peripheral region is short and not well formed. Peripheral spicules arranged individually, or multiple spicules branch tangentially to the axis in a plumoreticulated fashion and ascend to, and usually protrude through, the ectosome. Styles in the axial and peripheral skeleton do not appear to be differentiated, but are irregularly arranged. Specialized ectosomal skeleton absent. Spiculation (Table 5). Megascleres. Styles, smooth, bent to sinuous, variable and hastate to somewhat blunt distally, no easily discernible size classes: 796 (463 – 1385) × 19 (15 – 23) µm, n = 20 (Fig. 7 E). Microscleres. Absent.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE29FFE95AD2A5AA6369FB48.taxon	etymology	Etymology. Named for the branching form of the species: Latin ramosus (adj. A).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE29FFE95AD2A5AA6369FB48.taxon	discussion	Remarks. The present material conforms to Ptilocaulis Carter, 1883 as diagnosed by the presence of a vaguely reticulated axial skeleton and extra-axial skeleton formed by fibrofascicles cored with styles and ending in surface scopiform processes which are distinctive for this genus (Alvarez & Hooper 2002). There are nine currently accepted species of Ptilocaulis worldwide (de Voogd et al. 2024), of which only one, Ptilocaulis spiculifer (Lamarck, 1814), was also recorded from the WIO by Ridley (1884), Burton (1959), Pulitzer-Finali (1993) and the Red Sea by Lévi (1965). However, the type locality of P. spiculifer is King Island, Tasmania, Australia and the species has a much smaller spicule size range than that found for Ptilocaulis ramosus Payne, Samaai & Gibbons sp. nov.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2CFFEB5AD2A2DD6214FDD1.taxon	diagnosis	Diagnosis. Halichondria with smooth or digitate surface (Erpenbeck & Van Soest 2002).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2CFFEB5AD2A22F620AFE6D.taxon	type_taxon	Type species. Halichondria (Halichondria) panicea (Pallas, 1766) (by subsequent designation).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2CFFE45AD2A18965DCFAE4.taxon	description	urn: lsid: zoobank. org: act: 131665 ED-C 41 B- 49 A 2 - 993 E- 7 CCC 06378 A 01 Figure 8 A – F, Table 6	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2CFFE45AD2A18965DCFAE4.taxon	materials_examined	Material examined. Holotype. SAMC-A 096901 (cross-reference TS 2339 & WSL-INV 94 (11 )): Walters Shoal Seamount, Grid WSL 044, Station ALG 10976, coll. RV Algoa, (33 ° 14.0 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.7 ’ S; 43 ° 55.6 ’ E), 25 – 28 m depth, 02 June 2014. Paratypes. SAMC-A 096898 (cross-reference TS 2336 & WSL-INV 94 (7 )), SAMC- A 096900 (cross-reference TS 2338 & WSL-INV 94 (10 )), SAMC-A 096902 (cross-reference TS 2340 & WSL-INV 94 (12 )): Walters Shoal Seamount, Grid WSL 044, Station ALG 10976, coll. RV Algoa, (33 ° 14.0 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.7 ’ S; 43 ° 55.6 ’ E), 25 – 28 m depth, 02 June 2014. Additional material. TS 2350 (WSL-INV 94 (22 )): Walters Shoal Seamount, Grid WSL 044, Station ALG 10976, coll. RV Algoa, (33 ° 14.0 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.7 ’ S; 43 ° 55.6 ’ E), 25 – 28 m depth, 02 June 2014. TS 2373 (WSL-INV 75 (14 )), TS 2374 (WSL-INV 75 (15 )), TS 2375 (WSLINV 75 (16 )), TS 2377 (WSL-INV 75 (18 )), TS 2378 (WSL-INV 75 (19 )), TS 2379 (WSLINV 75 (20 )), TS 2380 (WSL-INV 75 (21 )): Walters Shoal Seamount, coll. RV Algoa, (33 ° 11.2 ' S; 43 ° 50.7 ' E), 29 m depth, 30 May 2014. TS 2381 (WSL-INV 83 (1 )), TS 2383 (WSL-INV 83 (3 )), TS 2384 (WSL-INV 83 (4 )), TS 2385 (WSL-INV 83 (5 )), TS 2387 (WSL-INV 83 (7 )): Walters Shoal Seamount, coll. RV Algoa, (33 ° 10.6 ' S; 43 ° 51.0 ' E), 29 m depth, 30 May 2014. TS 2390 (WSL-INV 92 (1 )), TS 2391 (WSL-INV 92 (2 )), TS 2392 (WSLINV 92 (3 )), TS 2393 (WSL-INV 92 (4 )): Walters Shoal Seamount, Grid WSL 043, Station ALG 10975, coll. RV Algoa, (33 ° 13.8 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.1 ’ S; 43 ° 55.8 ’ E), 28 – 30 m depth, 02 June 2014. TS 2481 (WSL-INV 84 (10 )), TS 2482 (WSL-INV 84 (11 )), TS 2483 (WSL-INV 84 (12 )), TS 2484 (WSL-INV 84 (13 )), TS 2485 (WSL-INV 84 (14 )), TS 2486 (WSL-INV 84 (15 )), TS 2490 (WSL-INV 84 (19 )), TS 2492 (WSL-INV 84 (21 )), TS 2499 (WSL-INV 84 (28 )): Walters Shoal Seamount, Grid WSL 042, Station ALG 10974, coll. RV Algoa, (33 ° 11.2 ’ S; 43 ° 51.0 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.7 ’ E), 28 – 34 m depth, 02 June 2014. Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2CFFE45AD2A18965DCFAE4.taxon	description	Description (Fig. 8 A). Thickly encrusting, semi-spherical form. Length 5.0 cm, diameter 4.0 cm and thickness 2.5 cm. Surface smooth, uneven, with various ridge-like structures. Oscules (1 – 2 mm) scattered randomly on the upper surface. Membrane present that covers the exterior. Texture spongy and dense, of medium compressibility and easily torn. Colour in life dark brown, with very dark brown (almost black) regions, light brown with dark brown regions in preservative. Specimen smells like soil and leaves a brown exudate on tissue paper. Skeleton (Fig. 8 B, C). Confused choanosomal skeleton, typically halichondrid, with oxeas of variable length arranged in a disorderly fashion (spicules distributed randomly), showing little tendency to form ascending tracts, and separated by well-developed subdermal spaces. The ectosomal skeleton typically comprises a tangential spicule layer of varying thickness (~ 100 – 300 µm), often becoming confused via intercrossing spicules. Spicules do not penetrate the surface. Ectosome not readily detachable from choanosome. Spiculation (Table 6). Megascleres. Oxeas, smooth, straight to slightly curved, fusiform, in three size classes: I) 416 (350 – 468) × 11 (6 – 14) µm, n = 20 (Fig. 8 D); II) 244 (208 – 288) × 8 (6 – 10) µm, n = 20 (Fig. 8 E); III) 144 (113 – 199) × 6 (5 – 7) µm, n = 20 (Fig. 8 F). Microscleres. Absent.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2CFFE45AD2A18965DCFAE4.taxon	etymology	Etymology. Named for the Madagascar Ridge, where Walters Shoal is located.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE2CFFE45AD2A18965DCFAE4.taxon	discussion	Remarks. The present material has a typically halichondrid skeleton (Erpenbeck & Van Soest 2002), with megascleres that are exclusively oxeas and oscules scattered randomly on the upper surface. Therefore, it is classified in the genus Halichondria Fleming, 1828. Due to the smooth, ridge-like surface, the species is further placed in the subgenus Halichondria Fleming, 1828. Seven species of Halichondria (Halichondria) Fleming, 1828 are described from the WIO and South Africa. These are Halichondria (Halichondria) capensis Samaai & Gibbons, 2005, Halichondria (Halichondria) gilvus Samaai & Gibbons, 2005, Halichondria (Halichondria) cartilaginea (Esper, 1794), Halichondria (Halichondria) lendenfeldi Lévi, 1961, Halichondria (Halichondria) aldabrensis Lévi, 1961, Halichondria (Halichondria) tenuiramosa Dendy, 1922 and Halichondria (Halichondria) prostrata Thiele, 1905 (de Voogd et al. 2024). Halichondria (Halichondria) madagascarensis Payne, Samaai & Gibbons sp. nov. is distinct from the seven species of Halichondria (Halichondria) Fleming, 1828 that have been identified in South Africa and the WIO region. This distinction is based on morphological differences and the presence of three size classes of oxeas. Halichondria (Halichondria) capensis and Halichondria (Halichondria) gilvus, both described by Samaai & Gibbons (2005) from the west coast of South Africa, have one size class of oxeas (333 (319 – 355) × 12 (12) µm, and 391 (328 – 437) × 15 (9 – 18) µm, respectively) with a relatively narrow size range. In addition, both H. (H.) capensis and H. (H.) gilvus have conspicuous papillae, as opposed to the present material which has irregular, spongy, easily deformed turrets. Within the WIO, Halichondria (Halichondria) cartilaginea and Halichondria (Halichondria) lendenfeldi also both have one size class of oxeas (185 – 203 × 3 – 4 µm; 400 – 600 × 11 – 13 µm, respectively) (Table 6). These two species also differ from the present material morphologically, with H. (H.) cartilaginea having a bushy form, with a slightly brittle consistency and small (0.02 mm) pores, while H. (H.) lendenfeldi has a hispid, velvety surface with many pores distributed over the entire surface. Halichondria (Halichondria) aldabrensis has two size classes of oxeas (I) 275 – 650 × 4 – 10 µm; II) 275 – 650 × 4 – 10 µm), which are larger than those found in the present material. Halichondria (Halichondria) tenuiramosa which occurs extensively in the Indian Ocean, has one size class of very small oxeas (210 × 6 µm), with a creeping, branching form. In contrast, Halichondria (Halichondria) prostrata, with its type locality in Tumbes, Quiriquina, Chile, has one size class of long, thin oxeas (300 – 320 × 9 µm) that are shorter than those found in the new species.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE23FFE45AD2A6AA6501FA16.taxon	type_taxon	Type species. Aaptos aaptos (Schmidt, 1864) (by original designation).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE23FFE75AD2A5596557FB70.taxon	description	urn: lsid: zoobank. org: act: A 9182140 - 153 C- 4386 - 985 E- 59 C 2 CF 13 AA 18 Figure 9 A – H, Table 7	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE23FFE75AD2A5596557FB70.taxon	materials_examined	Material examined. Holotype. SAMC-A 096926 (cross-reference TS 2502 & WSL-INV 84 (31 )): Walters Shoal Seamount, Grid WSL 042, Station ALG 10974, coll. RV Algoa, (33 ° 11.2 ’ S; 43 ° 51.0 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.7 ’ E), 28 – 34 m depth, 02 June 2014. Paratype. SAMC-A 096927 (cross-reference TS 2503 & WSL-INV 84 (32 )): Walters Shoal Seamount, Grid WSL 042, Station ALG 10974, coll. RV Algoa, (33 ° 11.2 ’ S; 43 ° 51.0 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.7 ’ E), 28 – 34 m depth, 02 June 2014. Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE23FFE75AD2A5596557FB70.taxon	description	Description (Fig. 9 A). Thickly encrusting form. Length 1.9 cm, diameter 1.7 cm and thickness 0.7 cm. A dense array of spicules at the surface (~ 1 mm), arranged in a confused fashion rendering the surface prickly to the touch. No visible oscules. Texture dense and firm, barely compressible specimens tear so-so. Colour in life dull black externally, almost appearing grey due to visible spicules at the surface. Internal colour in life beige. Colour in preservative dull brown externally, internally grey-beige. Skeleton (Fig. 9 B, C, D). Choanosomal skeleton comprises dense tracts of megascleres (~ 230 – 290 µm wide) that arise from the base and radiate vertically through the choanosome, fanning out and forming brushes into the ectosome. These brushes form a dense palisade at the surface, with smaller spicules intermingled (often perpendicular to surface) between the larger spicules. Subectosomal region consists of a layer of densely packed, tangentially orientated megascleres. Ectosome consists of small styles and larger intermediate styles, which form palisades of vertically arranged brushes. The distal ends of these megascleres protrude through the sponge surface. Spiculation (Table 7). Megascleres. Strongyloxeas, smooth, straight to slightly bent, thickest centrally with reduced apices, distally fusiform: 988 (678 – 1285) × 16 (8 – 20) µm, n = 20 (Fig. 9 E). Styles, smooth, straight to slightly bent, often thickest centrally in largest size class, distally fusiform, in three size classes: I) 925 (674 – 1282) × 27 (24 – 32) µm, n = 20 (Fig. 9 F); II) 444 (348 – 576) × 13 (8 – 20) µm, n = 20 (Fig. 9 G); III) 197 (128 – 291) × 5 (3 – 7) µm, n = 20 (Fig. 9 H). Microscleres. Absent. Substratum, depth range and ecology. Two specimens found in one sled on rocky substrata. Depth range: 28 – 34 m.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE23FFE75AD2A5596557FB70.taxon	etymology	Etymology. This species is named after the encrusting habit.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE23FFE75AD2A5596557FB70.taxon	discussion	Remarks. The present material has a radiate skeleton of strongyloxeas, with a dense ectosomal palisade and is thus placed in the genus Aaptos Gray, 1867 (Van Soest 2002). Aaptos incrustans Payne, Samaai & Gibbons sp. nov. is distinct from the two species of Aaptos that have been recorded from South Africa: Aaptos alphiensis Samaai & Gibbons, 2005 and Aaptos nuda (Kirkpatrick, 1903). Aaptos alphiensis was described by Samaai & Gibbons (2005) from the west coast of South Africa, as having both primary and intermediate subtylostyles, intermediate styles and dermal tylostyles, while Kirkpatrick (1903) notes the presence of only oxeas in A. nuda. The comparative spicule measurements are in Table 7. There have been several records of Aaptos aaptos (Schmidt, 1864), which has both strongyloxeas and styles, in the Indian Ocean. However, the World Porifera Database (de Voogd et al. 2024) suggests that these records are inaccurate due to the type location being in the Adriatic Sea.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE26FFE15AD2A22F6213FE6D.taxon	type_taxon	Type species. Lissodendoryx (Lissodendoryx) isodictyalis (Carter, 1882) (by original designation).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE26FFE25AD2A11D6778F9C4.taxon	description	urn: lsid: zoobank. org: act: F 12369 E 5 - AFB 9 - 40 FB-A 331 - 7 A 4 C 3 E 6 A 8648 Figure 10 A – I, Table 8	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE26FFE25AD2A11D6778F9C4.taxon	materials_examined	Material examined. Holotype. SAMC-A 096909 (cross-reference TS 2364 & WSL-INV 75 (5 )): Walters Shoal Seamount, coll. RV Algoa, (33 ° 11.2 ' S; 43 ° 50.7 ' E), 29 m depth, 30 May 2014. Paratypes. SAMC-A 096910 (cross-reference TS 2365 & WSL-INV 75 (6 )), SAMC-A 096911 (cross-reference TS 2366 & WSL-INV 75 (7 )), SAMC- A 096912 (cross-reference TS 2367 & WSL-INV 75 (8 )), SAMC-A 096913 (cross-reference TS 2368 & WSL-INV 75 (9 )): Walters Shoal Seamount, coll. RV Algoa, (33 ° 11.2 ' S; 43 ° 50.7 ' E), 29 m depth, 30 May 2014. Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE26FFE25AD2A11D6778F9C4.taxon	description	Description (Fig. 10 A, B). Massive, ridge-shaped form. Length 13.0 cm, width 7.5 cm and thickness 2.6 cm. Surface smooth and uneven, or markedly coarse with a thin, transparent membrane covering the entire exterior. Oscules (up to 5 mm in size) present, scattered randomly on top of the ridge. Texture firm but spongy, compressible and not easily torn. Colour in situ beige to pale yellow; lab photo light red to orange externally; in preservative, beige. Skeleton (Fig. 10 C, D). Choanosomal skeleton comprises a fairly tight-meshed regular renieroid reticulation, with primary fibres ~ 40 µm across, running obliquely to the surface, composed of spongin and cored by groups of 1 – 3 smooth styles, diverging in a plumoreticulate manner to ectosome. Secondary fibres ~ 20 – 30 µm across, enter the primary fibres at an angle, cored by single styles. Primary and secondary fibres with spongin, without a distinct sheath. Ectosomal skeleton comprises a distinct and continuous palisade of tylotes, perpendicular to and penetrating the surface, sometimes forming radiating bouquets ~ 150 – 200 µm deep. Microscleres scattered throughout. Spiculation (Table 8). Megascleres. Ectosomal tylotes, smooth, straight shafted, with elongated, well-developed heads: 184 (164 – 197) × 5 (3 – 6) µm, n = 20 (Fig. 10 E). Styles smooth, slightly curved with pronounced shaft and hastate end: 130 (117 – 140) × 6 (4 – 7) µm, n = 20 (Fig. 10 F). Microscleres. Sigmas, both C- and S-shaped: 29 (23 – 32) µm, n = 20 (Fig. 10 G). Arcuate isochelae in two size classes: I) 24 (22 – 25) µm, n = 20 (Fig. 10 H); II) 13 (12 – 14) µm, n = 20 (Fig. 10 I).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE26FFE25AD2A11D6778F9C4.taxon	etymology	Etymology. The name ‘ ingolei ’ was given in honour of Dr Baban Ingole, a colleague and friend, from the National Centre for Polar and Ocean Research (NCPOR), Goa, India, for his contributions to our understanding of the deep-water fauna of the South West Indian and Central Indian Ocean Ridges.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE26FFE25AD2A11D6778F9C4.taxon	discussion	Remarks. Lissodendoryx Topsent, 1892, is a diverse genus with a cosmopolitan distribution, currently comprising 125 valid species as documented in the World Porifera Database (de Voogd et al. 2024). Five subgenera are recognized in Lissodendoryx since Van Soest (2002) proposed a revised classification for the Coelosphaeridae. These subgenera are distinguished by their skeletal architecture and spicule categories. The new species possess a reticulate choanosomal architecture with a single category of acanthostyles. Therefore, we have classified our species as Lissodendoryx (Lissodendoryx). According to the World Porifera Database (de Voogd et al. 2024), there are currently 69 valid species recognized within Lissodendoryx (Lissodendory x). Of these, only six Lissodendoryx (Lissodendory x) species have been recorded or described from South Africa and the Western Indian Ocean (de Voogd et al. 2024). These are Lissodendoryx (Lissodendoryx) digitata (Ridley & Dendy, 1886), Lissodendoryx (Lissodendoryx) areolata Lévi, 1963, Lissodendoryx (Lissodendoryx) stephensoni Burton, 1936; Lissodendoryx (Lissodendoryx) ternatensis (Thiele, 1903), Lissodendoryx (Lissodendoryx) pygmaea (Burton, 1931) and Lissodendoryx (Lissodendoryx) monticularis Baer, 1906. The six species are compared to the new species described above. Lissodendoryx (Lissodendoryx) ingolei Payne, Samaai & Gibbons sp. nov. is distinct from Lissodendoryx (Lissodendoryx) pygmaea (Burton, 1931), originally described as Myxilla pygmaea from Natal, South Africa, by having longer megascleres and sigmas (see Table 8) and by being massively ridge-shaped, as opposed to being massively flabellate, as described for Lissodendoryx (Lissodendoryx) pygmaea. Burton (1931) noted that Lissodendoryx (Lissodendoryx) pygmaea may be allied with, or identical to, Lissodendoryx (Lissodendoryx) isodictyalis (Carter, 1882) described from the Caribbean, but disregarded this notion due to the latter species’ distribution. It is highly unlikely that Lissodendoryx (Lissodendoryx) isodictyalis would spread from the Central Atlantic across to the southern WIO. Lissodendoryx (L.) pygmaea was also noted by Lévi (1963, 1969) to resemble the type specimen of Lissodendoryx (Lissodendoryx) ternatensis (Thiele, 1903) described from Ternate, Indonesia, and a specimen from Vema Seamount (off South Africa), which he described as the latter species. Hofman & Van Soest (1995) indicated that L. (L.) pygmaea may possibly be a closely related, but a separate species to L. (L.) ternatensis, with the latter species having two classes of sigmas. Lissodendoryx (Lissodendoryx) digitata is described from the Agulhas Bank, located on the south coast of South Africa, and it has a digitate form. According to Ridley and Dendy (1886, 1887), the styles are large and entirely spined, lacking sigmas, and the species possesses only one category of large chelae (Table 8). Additionally, L. (L) digitata differs in having a larger category of tylostyles (Table 8). Lissodendoryx (Lissodendoryx) areolata Lévi, 1963, is flabelliform, widening into a blade and attached by a pedunculated base. The species lacks tylotes, and the acanthostyles are almost smooth, with some scattered spines on the head of the spicule (Lévi, 1963). Overall, the spicule sizes are larger than those found in the new species (Table 8). Lissodendoryx (Lissodendoryx) stephensoni Burton, 1936 described from the west coast of South Africa has larger sigmas and tylotes than those found in Lissodendoryx (Lissodendoryx) ingolei sp. nov. This species also has only one category of chelae, which are similar in diameter to the larger chelae found in Lissodendoryx (Lissodendoryx) ingolei sp. nov. (Table 8). Lissodendoryx (Lissodendoryx) monticularis Baer, 1906 described from Zanzibar has small sigmas (Table 8) and only one category of chelae, which are similar in diameter to the small chelae found in Lissodendoryx (Lissodendoryx) ingolei sp. nov. Lissodendoryx (Lissodendoryx) ternatensis, described from Indonesia, has on average larger styles and sigmas (Table 8) and also has two categories of sigmas. Thiele (1903) noted that a smaller form, half the length of the large sigma, was also observed (see also Hofman & Van Soest, 1995). We consider it highly unlikely that L. (L.) ternatensis would spread from the Central Indo-Pacific to the WIO, South Africa, and across to Vema Seamount in the South Atlantic. Lissodendoryx (Lissodendoryx) ingolei sp. nov. is distinct from Lissodendoryx (Lissodendoryx) ternatensis based on forementioned differences and the disjunct distribution of L. (L.) ternatensis. The species reported here is considered well differentiated from other Lissodendoryx (Lissodendoryx) species. Therefore, it appears that there are no species so closely related to the new species that doubts might arise regarding its validity.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE25FFE25AD2A5CE654BF8CA.taxon	type_taxon	Type species. Fibulia carnosa Carter, 1886 (type by monotypy).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE25FFDF5AD2A47D6246FB48.taxon	description	urn: lsid: zoobank. org: act: 26 A 60 B 99 - FA 5 C- 4 B 42 - B 6 B 1 - 4 D 8 C 2593 C 167 Figure. 11 A – E, Table 9	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE25FFDF5AD2A47D6246FB48.taxon	materials_examined	Material examined. Holotype. SAMC-A 096921 (cross-reference TS 2472 & WSL-INV 84 (1 )): Walters Shoal Seamount, Grid WSL 042, Station ALG 10974, coll. RV Algoa, (33 ° 11.2 ’ S; 43 ° 51.0 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.7 ’ E), 28 – 34 m depth, 02 June 2014. Paratypes. SAMC-A 096889 (cross-reference TS 2303 & WSL-INV 55): Walters Shoal Seamount, Grid WSL 022, Station ALG 10954, coll. RV Algoa, (33 ° 10.9 ’ S; 43 ° 48.6 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.2 ’ E), 72 – 170 m depth, 29 May 2014. SAMC-A 096922 (cross-reference TS 2473 & WSL-INV 84 (2 )), SAMC-A 096925 (cross-reference TS 2477 & WSL-INV 84 (6 )): Walters Shoal Seamount, Grid WSL 042, Station ALG 10974, coll. RV Algoa, (33 ° 11.2 ’ S; 43 ° 51.0 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.7 ’ E), 28 – 34 m depth, 02 June 2014. Additional material. TS 2487 (WSL-INV 84 (16 )), TS 2497 (WSL-INV 84 (26 )), TS 2510 (WSL-INV 84 (39 )): Walters Shoal Seamount, Grid WSL 042, Station ALG 10974, coll. RV Algoa, (33 ° 11.2 ’ S; 43 ° 51.0 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.7 ’ E), 28 – 34 m depth, 02 June 2014. Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE25FFDF5AD2A47D6246FB48.taxon	description	Description (Fig. 11 A). Thickly encrusting and amorphous form. Length 3.8 cm, width 3.0 cm and thickness 1.1 cm. Surface smooth and slippery, with ridges and randomly scattered oscules. Oscules, ~ 1 – 2 mm in diameter, often slightly indented. Texture rubbery, firm and dense. Specimen not compressible, nor easily torn. In one specimen (TS 2303), bright orange-red spherical eggs (~ 1 mm diameter) present. Colour in life dark red, light brown in preservative. Preservative becomes bright orange with time. Most specimens leave a red-brown exudate on tissue paper. Skeleton (Fig. 11 B, C). Choanosome contains a multispicular reticulate skeleton, comprised of robust fibres arranged somewhat radially, cored with oxeas. Fibres ~ 100 µm thick, sinuous, running somewhat perpendicular to the surface, not differentiated into primary and secondary tracts. Oxeas and arcuate chelae scattered throughout. Fibres penetrate ectosome, expanding radially to form brushes. Ectosome contains erect, radial bouquets of oxeas that sometimes pierce the surface, <200 µm thick. Spiculation (Table 9). Megascleres. Oxeas hastate, smooth, straight or slightly curved: 319 (282 – 342) × 6 (4 – 8) µm, n = 20 (Fig. 11 D). Microscleres. Arcuate unguiferous isochelae: 14 (12 – 15) µm, n = 20 (Fig. 11 E). Substratum, depth range and ecology. Seven specimens found on rocky substrata in two sleds, almost always in association with the same species of hydroid as epifauna. Depth range: 28 – 170 m.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE25FFDF5AD2A47D6246FB48.taxon	etymology	Etymology. The specific epithet punicea comes from Latin and means crimson or dark red.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE25FFDF5AD2A47D6246FB48.taxon	discussion	Remarks. The present material conforms to the genus Fibulia Carter, 1886 as diagnosed having a plumose or confused choanosomal skeleton of multispicular tracts; microscleres arcuate or reduced isochelae and the presence of only a single size category of oxeas (Van Soest 2002). The present material is compared with Fibulia ramosa (Ridley & Dendy, 1886) and Fibulia ectofibrosa (Lévi, 1963) from South Africa, Fibulia occiensis Rengaiyan, Kurian Palayil & Ingole, 2022 from the Central Indian Ocean Ridge, Fibulia myxillioides (Burton, 1932) from the Patagonian Shelf, and Fibulia novaezealandiae (Brøndsted, 1924) from New Zealand. Note that F. ectofibrosa is currently assigned to the genus Isodictya in the World Porifera Database (de Voogd et al., 2024), though Samaai & Gibbons (2005) considered it to belong to the genus Fibulia due to the presence of arcuate isochelae and a single size class of oxeas, rather than the palmate isochelae that are diagnostic of Isodictya. The oxeas of Fibulia punicea Payne, Samaai & Gibbons sp. nov. are similar in average size to those of F. ramosa, F. ectofibrosa, F. myxillioides and F. novaezealandiae (Table 9). The chelae are also similar in size range to those of F. novaezealandiae recorded from New Zealand (Table 9). Burton (1932) described Fibulia myxillioides as an erect, arborescent sponge with flattened anastomosing branches, or sub lamellate, with straight and smooth oxeas measuring 300 × 6 µm and arcuate isochelae of 30 µm (Table 9). Fibulia ramosa is cylindrical and branched, possessing large (600 × 22 µm) fusiform oxeas, and medium size arcuate isochelae (20 µm). Fibulia occiensis is stalked and club-shaped with large oxeas (628 (483 – 700) × 19 (14.5 – 21) μm) and large, well-formed arcuate isochelae, 36 (30 – 40.5) μm (Table 9). These species have different spicule sizes and also differ from F. punicea sp. nov. in terms of external morphology: F. punicea sp. nov. is thickly encrusting and dark red in colour. Fibulia novaezealandiae, on the other hand, is encrusting and characterised by slender oxeas with long tapering points (350 × 6 µm). The arcuate isochelae are small (12 – 14 μm) and although similar in size range to F. punicea sp. nov. (Table 9), they are strongly curved, with lateral teeth that stand vertically outward and are relatively long. Fibulia novaezealandiae also has its type locality in New Zealand and has not been recorded anywhere else (de Voogd et al. 2024). It is highly unlikely that F. novaezealandiae would spread from New Zealand to the WIO or to an isolated shallow seamount on the Madagascar ridge, given that it has not been recorded from any other region in the Indo-Pacific (de Voogd et al. 2024). Fibulia ectofibrosa is massive, light yellow-grey sponge, with straight or slightly curved hastate oxeas with unequal ends, 300 – 375 × 10 – 12 μm [Samaai & Gibbons 2005: 353 (318 – 382) × 14 (14) μm] and arcuate isochelae, 16 μm [Samaai & Gibbons 2005: 18 (18) μm]. Fibulia punicea sp. nov. is thickly encrusting and dark red in colour, with oxea ends that are equally hastate. The chelae’s shaft is roundly curved, and the frontal alae are sharply pointed but not well-formed (e. g. Fibulia occiensis) and arranged in a group of three alae.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE18FFDF5AD2A51D624FF987.taxon	type_taxon	Type species. Clathria (Clathria) compressa Schmidt, 1862 (by subsequent designation).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE18FFDF5AD2A67A62C8FA22.taxon	type_taxon	Type species. Clathria compressa Schmidt, 1862: 58 (by subsequent designation; Schmidt, 1864: 35).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE18FFD05AD2A5B76756F8ED.taxon	description	urn: lsid: zoobank. org: act: 67 DCF 563 - 3 F 82 - 48 E 4 - 81 E 2 - 783 E 4 C 619 CB 4 Figure 12 A – K, Tables 10, 11	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE18FFD05AD2A5B76756F8ED.taxon	materials_examined	Material examined. Holotype. SAMC-A 096904 (cross-reference TS 2342 & WSL-INV 94 (14 )): Walters Shoal Seamount, Grid WSL 044, Station ALG 10976, coll. RV Algoa, (33 ° 14.0 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.7 ’ S; 43 ° 55.6 ’ E), 25 – 28 m depth, 02 June 2014. Paratypes. SAMC-A 096888 (cross-reference TS 2302 & WSL-INV 54): Walters Shoal Seamount, Grid WSL 022, Station ALG 10954, coll. RV Algoa, (33 ° 10.9 ’ S; 43 ° 48.6 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.2 ’ E), 72 – 170 m depth, 29 May 2014. SAMC-A 096905 (cross-reference TS 2348 & WSL-INV 94 (20 )), SAMC-A 096907 (cross-reference TS 2355 & WSL-INV 94 (27 )): Walters Shoal Seamount, Grid WSL 044, Station ALG 10976, coll. RV Algoa, (33 ° 14.0 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.7 ’ S; 43 ° 55.6 ’ E), 25 – 28 m depth, 02 June 2014. Additional material. TS 2399 (WSL-INV 92 (10 )), TS 2422 (WSL-INV 92 (11 )): Walters Shoal Seamount, Grid WSL 043, Station ALG 10975, coll. RV Algoa, (33 ° 13.8 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.1 ’ S; 43 ° 55.8 ’ E), 28 – 30 m depth, 02 June 2014. TS 2508 (WSL-INV 84 (37 )), TS 2511 (WSL-INV 84 (40 )): Walters Shoal Seamount, Grid WSL 042, Station ALG 10974, coll. RV Algoa, (33 ° 11.2 ’ S; 43 ° 51.0 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.7 ’ E), 28 – 34 m depth, 02 June 2014. ...... continued on the next page ...... continued on the next page ...... continued on the next page ...... continued on the next page ...... continued on the next page ...... continued on the next page Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE18FFD05AD2A5B76756F8ED.taxon	description	Description (Fig. 12 A). Thickly encrusting, lobate form. Length 3.4 cm, width 2.5 cm and thickness 1.3 cm. Surface undulating but smooth and velvety, with randomly scattered small, round oscules (<1 mm in diameter), sunken with no distinct membranous lip. Texture soft and spongy, compressible and easily torn. Colour in life orange, beige in preservative. Skeleton (Fig. 12 B, C). Choanosomal skeleton regularly reticulate, forming irregular anastomoses of differentiated primary and secondary fibres, diverging in plumoreticulate manner towards ectosome. Fibres are differentiated into primary and secondary transverse components. Primary fibres cored with principal styles, cemented by spongin that does not form a distinct sheath around the fibre and echinated by acanthostyles. Secondary fibres with unispicular tracts of principal styles. Ectosomal and subectosomal skeleton consists of principal styles and auxiliary subtylostyles, with the former arising from ascending choanosomal tracts being slightly plumose and diverging into erect bundles that project obliquely through the surface. The latter form compact diverging brushes at the ectosomal surface, barely penetrating the subectosomal membrane. Microscleres scattered throughout choanosome. Spiculation (Table 10). Megascleres. Styles, smooth, curved, with well-rounded to almost subtylote-like base, distally hastate: 234 (179 – 320) × 9 (8 – 12) µm, n = 10 (Fig. 12 D). Subtylostyles, smooth, straight with a terminally spined elongated base, distally fusiform: 211 (130 – 313) × 3 (2 – 4) µm, n = 10 (Fig. 12 E, F). Acanthostyles, straight to slightly bent, with well-rounded to almost subtylote-like base, distally hastate: 138 (132 – 148) × 7 (6 – 10) µm, n = 10 (Fig. 12 G). Microscleres. Toxas, terminally spined, in two size classes: I) 146 (111 – 177) µm, n = 20 (Fig. 12 H); II) 45 (35 – 61) µm, n = 20 (Fig. 12 I, J). Palmate isochelae: 13 (11 – 14) µm, n = 10 (Fig. 12 K).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE18FFD05AD2A5B76756F8ED.taxon	etymology	Etymology. The species name ‘ flo’ is dedicated to Dr Wayne Florence from the Iziko Museums of South Africa (Cape Town). This name honours Dr Florence for his significant contributions to our knowledge of the Bryozoa fauna in South Africa. Additionally, Dr Florence is acknowledged for his support in providing laboratory space and resources to Dr Toufiek Samaai.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE18FFD05AD2A5B76756F8ED.taxon	discussion	Remarks. The present material conforms to Clathria (Clathria) Schmidt, 1862 as diagnosed by a single category of auxiliary style and no marked difference between the axial and extra-axial regions in the choanosomal skeleton (Hooper 2002). There are 19 species of Clathria (Clathria) found within the WIO and South Africa (de Voogd et al. 2024), none of which are conspecific with C. (C.) flo sp. nov. (see Tables 10, 11) Of the 19 species of Clathria (Clathria) recorded from the WIO and South Africa, one species, Clathria (Clathria) lobata Vosmaer, 1880, has terminally spined toxas (Table 10). Clathria (Clathria) lobata, however, has large megascleres and is erect branching. Five species — Clathria (Clathria) omegiensis Samaai & Gibbons, 2005; Clathria (Clathria) rhaphidotoxa Stephens, 1915; Clathria (Clathria) inhacensis Thomas, 1979; Clathria (Clathria) decumbens Ridley, 1884; and Clathria (Clathria) maeandrina Ridley, 1884 — are encrusting (Table 11). All 19 Clathria (Clathria) species differ substantially from Clathria (Clathria) flo Payne, Samaai & Gibbons sp. nov. in major features such as growth form, spicule geometries, spicule sizes, spicule structure and skeletal architecture (Table 10, 11).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE14FFCD5AD2A2DF62B9FF10.taxon	description	urn: lsid: zoobank. org: act: CE 128 D 4 B- 8436 - 4 C 06 - A 2 BC-BC 29283866 A 2 Figure 13 A – E, Table 12	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE14FFCD5AD2A2DF62B9FF10.taxon	materials_examined	Material examined. Holotype. SAMC-A 096914 (cross-reference TS 2369 & WSL-INV 75 (10 )): Walters Shoal Seamount, coll. RV Algoa, 29 m depth, 30 May 2014. Paratypes. SAMC-A 096897 (cross-reference TS 2330 & WSL-INV 94 (1 )), SAMC-A 096903 (cross-reference TS 2341 & WSL-INV 94 (13 )), SAMC-A 096906 (cross-reference TS 2353 & WSL-INV 94 (25 )): Walters Shoal Seamount, Grid WSL 044, Station ALG 10976, coll. RV Algoa, (33 ° 14.0 ’ S; 43 ° 55.5 ’ E) - (33 ° 13.7 ’ S; 43 ° 55.6 ’ E), 25 – 28 m depth, 02 June 2014. Additional material. TS 2370 (WSL-INV 75 (11 )), TS 2371 (WSL-INV 75 (12 )): Walters Shoal Seamount, coll. RV Algoa, 29 m depth, 30 May 2014. TS 2382 (WSL-INV 83 (2 )): Walters Shoal Seamount, coll. RV Algoa, 29 m depth, 30 May 2014. TS 2479 (WSL-INV 84 (8 )): Walters Shoal Seamount, Grid WSL 042, Station ALG 10974, coll. RV Algoa, (33 ° 11.2 ’ S; 43 ° 51.0 ’ E) - (33 ° 11.2 ’ S; 43 ° 50.7 ’ E), 28 – 34 m depth, 02 June 2014. TS 2537 (WSL-INV 102 (3 )): Walters Shoal Seamount, Grid WSL 045, Station ALG 10977, coll. RV Algoa, (33 ° 13.8 ’ S; 43 ° 56.1 ’ E) - (33 ° 14.2 ’ S; 43 ° 55.9 ’ E), 80 m depth, 02 June 2014. Type locality. Walters Shoal Seamount, south of Madagascar on the Madagascar Ridge, Western Indian Ocean (Fig. 1).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE14FFCD5AD2A2DF62B9FF10.taxon	description	Description (Fig. 13 A, B). Massive, predominantly ramose but tubular, growing from a common base, from which upright clusters of finger-like projections arise, interconnected laterally. Tubes usually coalesced for a greater or lesser distance, occasionally united along entire length. Length 6.0 cm, width 9.1 cm and thickness 1.4 cm. Tube diameter 3 cm. Surface smooth and velvety to the touch. Oscules (3 – 9 mm diameter) present at the apex of the tubes, which become fibrous at the tips. Transparent membrane covering exterior. Texture soft and spongy, compressible and easily torn. Colour in life bright blue, turning beige with purple tips above water. In preservative, pale yellow. Skeleton (Fig. 13 C, D). Choanosome with a regularly rectangular-meshed skeleton formed by multispicular primary spongin fibres ~ 30 µm wide, and ~ 71 – 430 µm apart, interconnected often perpendicularly by secondary unispicular fibres ~ 20 µm thick, forming meshes ~ 110 – 250 µm wide. Unispicular tertiary fibres sometimes present, ~ 25 µm thick, forming meshes ~ 80 µm thick, which interconnect secondary fibres perpendicularly. Specialised ectosomal skeleton absent. Spiculation (Fig. 13 E; Table 12). Megascleres. Oxeas, short, smooth, straight to slightly curved medially, hastate: 64 (57 – 69) × 3 (2 – 4) µm, = 20. Microscleres. Absent. Substratum, depth range and ecology. Nine specimens found on rocky substrata in three sleds and both dives, often with crinoids as epifauna. Depth range: 25 – 80 m.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE14FFCD5AD2A2DF62B9FF10.taxon	etymology	Etymology. The species name cacumen is derived from the Latin noun " cacumen, " which is gender-neutral and means " summit. " This name was chosen to reflect the species' occurrence on the summit or crown area of the shallow regions of Walters Shoal.	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE14FFCD5AD2A2DF62B9FF10.taxon	discussion	Remarks. The present material conforms to the genus Callyspongia (Callyspongia) Duchassaing & Michelotti, 1864 as diagnosed by a single ectosomal non-hispid layer, multispicular well-defined choanosomal fibres with a distinct spongin sheath, forming a rectangular mesh without free spicules, and a smooth surface (Desqueyroux-Faúndez & Valentine 2002). The present material is not conspecific with the three species of this subgenus that have been recorded from the region of interest (de Voogd et al. 2024): Callyspongia (Callyspongia) differentiata (Dendy, 1922), Callyspongia (Callyspongia) reticutis (Dendy, 1905) and Callyspongia (Callyspongia) tubulosa (Linnaeus, 1759) sensu (Esper, 1797), the latter of which was re-described by Samaai & Gibbons in 2005. Both C. (C.) differentiata and C. (C.) reticutis have slightly larger spicule sizes (80 × 3 µm and 72 × 2.6 µm, respectively) but also differ from the present material with regards to skeletal structure, with the former having secondary fibres devoid of spicules and the latter having multispicular secondary fibres. Callyspongia (C.) tubulosa is most similar morphologically to the present material, but has larger oxeas (110 – 140 × 13 µm) with multispicular secondary fibres (Table 12).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE14FFD35AD2A23F6366FE79.taxon	type_taxon	Type species. Callyspongia (Callyspongia) fallax Duchassaing & Michelotti, 1864 (by subsequent designation).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
71628244AE14FFD35AD2A39F6200FF19.taxon	type_taxon	Type species. Callyspongia fallax Duchassaing & Michelotti, 1864 (by subsequent designation).	en	Payne, Robyn P., Samaai, Toufiek, Janson, Liesl, Kerwath, Sven E., Gibbons, Mark J. (2025): Eleven new heteroscleromorph Demospongiae (Porifera), and a new record of the tetractinellid Ancorina corticata, from Walters Shoal, a shallow seamount on the Madagascar Ridge in the South West Indian Ocean (SWIO). Zootaxa 5575 (1): 1-56, DOI: 10.11646/zootaxa.5575.1.1, URL: https://doi.org/10.11646/zootaxa.5575.1.1
