taxonID	type	description	language	source
4F308799FFACFFFBFE8C7E90FEE1F857.taxon	type_taxon	TYPE SPECIES. — Orbicula antillarum d’Orbigny, 1845: by original designation (Stenzel 1964: 627).	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFACFFFBFE8C7E90FEE1F857.taxon	discussion	REMARKS Discradisca was introduced by Stenzel (1964) as a subgenus of Discinisca Dall, 1871 when he wanted to distinguish those species having radial costellae on the dorsal valve from those lacking costellae. Later Cooper (1977) elevated Discradisca to generic rank. In the revised Treatise, Holmer & Popov (2000) distinguished Discradisca and Discinisca on the basis of the ventral valve: “ similar to Discinisca, but with wide, transversely suboval pedicle track, closed apically by semicircular, gently concave listrium ”. However, fossil assemblages generally contain mostly dorsal valves (some exceptions were mentioned by Radwańska & Radwański 2003) and ventral valves are not always known even in the case of recent materials. Therefore, it is expedient to return to Stenzel’s original definition that distinguishes Discradisca based on radial costellae on the dorsal valve, especially if only dorsal valves are available (e. g., Dulai 2013; Bitner & Cahuzac 2013; Ishizaki & Shiino 2023, 2024). Regarding the radial ridges on discinide valves, Williams et al. (1997) distinguished primary radiated ridges (costae) from secondarily branched ridges (costellae). In this paper we follow the work of Ishizaki & Shiino (2023) who did not distinguish between primary and secondary ridges, but referred to them uniformly as costellae. Discinide species are traditionally subdivided into three types (A, B, and C) based on dorsal valve characteristics (Dall 1920; Radwańska & Radwański 1984; Ishizaki & Shiino 2024: fig. 10): Type A: large, lamellose shell without radial costellae; Type B: large, weakly lamellose shell with faint irregular costellae; Type C: small, non-lamellose shell, with regular radial costellae. Taking into account the abovementioned criteria, species of type B and C are classified in the genus Discradisca (although it may be argued that type B might deserve to be placed in a separate genus). The painful lack of knowledge about the ventral valve of the fossil species of Discinisca and Discradisca is excellently illustrated by the carefully compiled summary figure by Ishizaki & Shiino (2024: fig. 10). They show that among the nine known Palaeogene and Neogene Discradisca species, we have no information at all on the ventral valve, and even among the Discinisca species, only three of the twelve species have a fossilised ventral valve: D. singewaldi (Scuchert in Berry 1917); D. elslooensis (Radwańska & Radwański 2003) and D. messii (Pérez et al. 2023). The ventral valve was also described and illustrated by Hertlein & Grant (1944) for the species D. perrini Loel & Corey, 1932 from Miocene strata in western North America. Currently six extant Discradisca species are known characterised by a warm-temperate to tropical, cosmopolitan distribution mainly over the continental shelves (Emig 1997 a, b): D. antillarum (d’Orbigny, 1845): the Atlantic coast of America from Cuba to Brazil; the Caribbean Sea at the coasts of Mexico, Cuba, Nicaragua, and Jamaica (d’Orbigny 1841 - 1853; Reeve 1862; Davidson 1888; Dall 1920; Cooper 1977; Tunnell 1982; Zezina 1985, 2010; Emig 2017: p. 33). D. cumingii (Broderip, 1834): the Pacific coasts of America from California Peninsula to 40 ° S (Mexico, Guatemala, Panama, Ecuador, Peru), Antarctic Peninsula, from the low tide line to 15 m of depth (Broderip 1834; Reeve 1862; Davidson 1888; Dall 1920; Zezina 1985, 2010; Zezina & Pakhnevich 1998; Gaspard 2001; Álvarez in Álvarez et al. 2016; Emig 2017). D. indica (Dall, 1920): India, Sri Lanka, Philippines, the Persian Gulf, and Indonesia (as Discinisca keiensis by Jackson & Stiasny 1937) at a depth of 51 - 68 and (?) 329 m (Dall 1920; Cooper 1973; Zezina 1985, 2010; Bitner et al. 2008). D. sparselineata (Dall, 1920): the coasts of Japan from Hakodate to Tokyo Bay (unknown depth) and French Polynesia (96 - 300 m) (Dall 1920; Hatai 1940; Kato 1983; Zezina 1985, 2010; Bitner 2014; Ogiso et al. 2014, 2019). D. stella (Gould, 1862): the Pacific coasts of Asia from Tokyo Bay to Hong Kong and to New Caledonia; Northern Australia and the seas of the Malay Archipelago at a depth of 31 - 141 m (Reeve 1862; Davidson 1888; Dall 1920; Hatai 1940; Zezina 1985, 2010; Richardson et al. 1989; Harper 1997; Bitner 2010; Emig 2017: 33; Otani 2019; Ogiso et al. 2019; Ishizaki & Shiino 2023). D. strigata (Broderip, 1834): the Pacific coasts of America from California to Panama at a depth of 5 - 33 m (Broderip 1834; Dall 1920; LaBarbera 1985; Zezina 1985, 2010; Emig 2009). So far, no Discradisca remains are known from Mesozoic formations (Ishizaki & Shiino 2024: fig. 1). The oldest extinct species of the genus is D. littigensis Stenzel, 1964 from the Lower Palaeocene (Danian) of Texas, USA (Stenzel 1964). Several extinct species of the genus are known from the Eocene to Miocene of Europe (e. g., Dreger 1889; Dollfus & Dautzenberg 1901; de Morgan 1915; Muir-Wood 1939; Čtyroký & Fejfar 1963; Radwańska & Radwański 1984, 1989; Popiel-Barczyk 1996; Kroh 2003; Kocsis et al. 2012; Bitner & Cahuzac 2013; Dulai 2013, 2015, 2017). Also, the genus is known from the Palaeogene (Hertlein & Grant 1944) and Neogene (Dall 1909; Portell & Harper 2005) of North America and from the Pleistocene, and possibly the Pliocene of Japan (Yabe & Hatai 1935; Hatai 1940; Hatai & Hayasaka 1965).	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFAFFFF7FEB87994FC2CFE6A.taxon	description	(Figs 2; 3; 4) urn: lsid: zoobank. org: act: B 8 C 22 B 6 C- 99 F 7 - 4 E 31 - 8540 - 3 D 257 D 7 CFC 13	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFAFFFF7FEB87994FC2CFE6A.taxon	materials_examined	TYPE MATERIAL. — Holotype. Malaysia • 1 specimen; Sarawak, Miri, Tanjong Lobang; intertidal zone; Raven leg.; alive on rocks; RMNH. BRA. 923 (Figs 2 A-C; 3; 4). Paratypes. Malaysia • 1 specimen; Sabah, Kota Kinabalu, Tanjung Aru beach; 1 - 2 m b. s. l.; Raven leg.; collected snorkelling; living attached to the bivalve Malleus malleus (Linnaeus, 1758) on rocks; RMNH. BRA. 924 (Fig. 2 D-E) • 1 specimen; Sarawak, offshore from Lutong, Atago Maru wreck; 12 m b. s. l.; Raven leg; alive on wreck; RMNH. BRA. 925 (Fig. 2 H-K). OTHER MATERIAL EXAMINED. — Malaysia • 1 specimen; Sarawak, near Bako, Telok Pandar Besar beach; tidal flat; J. J. Vermeulen leg.; in fine shell grit in an area with rocks, mangroves and wide silty tidal flat; RMNH. BRA. 937 • 1 juvenile specimen; Sarawak, Miri, 26.4 km W of Tanjong Lobang, Tukau reef; 20 m b. s. l.; Raven leg.; collected scuba diving; between coral rubble on coral bank; RMNH. BRA. 926 • 1 specimen; Sarawak, Miri, SW of Tanjong Lobang, Grouper Patch, 30 km from shore; 16 m b. s. l.; Raven leg.; collected scuba diving; between coral rubble on coral bank; RMNH. BRA. 927 (Fig. 2 G) • 3 juvenile specimens; Sarawak, Miri, 11.6 km SW of Tanjong Lobang, Azam’s Place; 20 m b. s. l.; Raven leg.; collected scuba diving; between coral rubble on coral bank; RMNH. BRA. 928 (Fig. 2 F) • 1 specimen + 2 juveniles; Sarawak, Miri, 6 km WNW of Tanjong Lobang, Shipwreck No. 1; 14 m b. s. l.; Raven leg.; collected scuba diving; living on shells on shipwreck; RMNH. BRA. 929 • 2 specimens; Sarawak, Miri, WSW of Tanjong Lobang, 10.1 km offshore, Outer reef; 6 m b. s. l.; Raven leg.; collected scuba diving; between coral rubble on coral bank; RMNH. BRA. 930 • 10 specimens; Sarawak, Miri, Tanjong Lobang; intertidal zone; Raven leg.; alive on rocks; RMNH. BRA. 931 • 1 specimen, 2 juveniles; Sarawak, offshore from Lutong, Atago Maru wreck; 12 m b. s. l.; Raven leg.; collected scuba diving; alive on shells on shipwreck; RMNH. BRA. 932 • 1 specimen; Sabah, Labuan, Kampong Pohon Batu; Raven leg.; RMNH. BRA. 935 • 1 specimen, 2 juveniles; Sabah, Kota Kinabalu, Tanjung Aru beach; 1 - 2 m b. s. l.; Raven leg.; collected snorkelling; living attached to Malleus malleus (Linnaeus, 1758) on rocks; RMNH. BRA. 936. Brunei • 5 specimens; Muara, Jerudong beach; 15 m b. s. l.; Raven leg.; sediment dredged; RMNH. BRA. 933 • 5 juveniles, 2 fragments; Muara, Jerudong beach; J. J. Vermeulen & K. Orr leg; RMNH. BRA. 934.	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFAFFFF7FEB87994FC2CFE6A.taxon	etymology	ETYMOLOGY. — Refers to the island of Borneo where all available specimens were found.	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFAFFFF7FEB87994FC2CFE6A.taxon	materials_examined	TYPE LOCALITY. — Tanjong Lobang, Miri, Sarawak, Malaysia; intertidal zone.	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFAFFFF7FEB87994FC2CFE6A.taxon	diagnosis	DIAGNOSIS. — Discradisca with low conical dorsal valve, ornamented by 125 - 135 tuberculate radial costellae. Irregularly subhexagonal ventral valve with elongated ovoid pedicle foramen, smooth white pedicle area. Outer part of the ventral valve ornamented by numerous (c. 180), closely spaced radial costellae, without tuberculated appearance.	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFAFFFF7FEB87994FC2CFE6A.taxon	distribution	DISTRIBUTION. — Apparently endemic to the southern South China Sea in NW Borneo. Known from Sarawak and Sabah (East Malaysia) and Brunei Darussalam. The records from NW Borneo are about 2500 km to the East from the Andaman Islands, from where D. semicornea was described by Preston (1908).	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFAFFFF7FEB87994FC2CFE6A.taxon	description	DESCRIPTION Dorsal valve Slightly irregular, chitinophosphatic thin shell with subcircular outline (Fig. 2 A, D, F-H). Small to medium sized (holotype: L: 12.8 mm, W: 12.1 mm, H: 2.2 mm), low-conical in profile (Fig. 2 C). Posterior slope straight, anterior slope slightly concave. Smooth apex in subcentral position (Fig. 2 A, D, F-H), slightly posterior to centre; often eroded in adults. Circular larval shell (protegulum) smooth, without growth lines, about 0.4 mm in diameter (Fig. 2 J). Post-larval (brephic) shell (L: c. 1 mm, W: c. 0.7 mm) elliptical, nearly smooth with some fine concentric growth lines and a few incipient radial costellae (Fig. 2 J). External surface of adult shell with numerous (up to 125 - 135 at 12 mm diameter) fine, well-pronounced but slightly irregular, tuberculate radial costellae, and relatively strong, somewhere faintly wavy concentric growth lines (Fig. 2 A, D, G, H). Costellae continuous and densely spaced, interspaces wider than ridges (Fig. 2 J-K). Irregular elongated pustules at the intersection of growth lines and radial costellae (Fig. 2 K). Number of costellae increasing by intercalation towards the edges (Fig. 2 A, H, J, K). Micro ornamentation of numerous very fine concentric grooves, both in interspaces and over grooves and pustules (Figs 2 J, K). Internal side smooth, but traces of external costellae sometimes on the internal surface (Fig. 2 B, E). Only anterior adductors well visible in smaller specimens, other muscle scars hardly detectable (Fig. 2 E, I). Muscle scars with concentric arrangement in fully grown valves (like the holotype) (Figs 2 B; 3). Anterior adductor I located laterally to internal side of apex, longitudinally elongated, narrow, curved anteriorly in a horseshoe-like shape, but not reaching each other. Posterior adductors narrow, laterally slightly elongated, situated near to the limbus. Lateral ends of posterior adductors connected to outer edge of anterior adductor I by a thin ridge. Anterior adductor II along inner side of anterior adductor I shorter, longitudinally elongated and slightly curved. Short elliptical oblique internal muscle scars situated between posterior adductor and posterior end of anterior adductor I. Oblique posterior muscle scars located between left and right posterior adductors, left one small subcircular, right one elongated, bean-shaped. Faint impressions of vascula media situated at anterior end of anterior adductor I and bend laterally. Possible vascula lateralia very uncertain and blurred at outer middle part of anterior adductor I (Fig. 2 B). Shell edge finely crenulate (Fig. 2 H-I). Limbus poorly and unevenly developed. Colour inside and outside pale yellowish. Ventral valve Corneous, thin, and flexible, with irregularly subhexagonal outline (Fig. 4). Pedicle area subcircular, smooth and white, with thickened brown border. Posteriorly placed pedicle foramen elongated ovoid, wider posteriorly and narrower anteriorly. A relatively small depressed area (sensu Ishizaki & Shiino 2024) seen only around the posterior third of the pedicle area. A short and low median septum situated between anterior end of pedicle foramen and border of pedicle area, however, possibly extending as in a very low ridge in outer, costellated part of shell. Outer part of ventral valve ornamented by closely spaced, slightly irregular radial costellae, without tuberculated appearance. Number of radial costellae increasing by both intercalation and bifurcation towards the shell margin, up to 180 at outer edge. All costellae pointing towards the central part of ventral shell, causing costellae on the posterior part of shell to fit into the rim of pedicle area.	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFAFFFF7FEB87994FC2CFE6A.taxon	discussion	REMARKS Three Discradisca species are known from the shallow waters of South Asia and Northern Australia: D. indica, D. stella, and D. sparselineata. The latter species can be distinguished by its strongly irregular dorsal valve with sparse radial costellae and very long setae (Dall 1920; Hatai 1940; Bitner 2014). Discradisca stella and D. indica are very similar in size, shape and ornamentation of the dorsal valve, however, they differ in the characters of the costellae, which are distinctly tuberculate and more widely spaced in D. indica (Cooper 1973; Bitner et al. 2008), while fine radial and not tuberculate in D. stella (Bitner 2010). In this regard, D. borneensis n. sp. from the South China Sea, located between the Indian and Pacific Oceans, definitely is more similar to D. indica. If we have only dorsal valves, we may conclude that the studied material from NW Borneo is within the intraspecific variability of D. indica. Some smaller differences can be found in the size (D. borneensis n. sp. seems to be larger), in number of costellae (125 - 135 in D. borneensis n. sp. vs 140 - 155 in D. indica), in position of apex (more central in borneensis n. sp., and more posteriorly situated in D. indica) and in the outline (more regular in D. borneensis n. sp., and more irregular in indica, especially in Bitner et al. 2008 material). However, if we also have the ventral valves, both species can be clearly distinguished as separate species. Discradisca indica ventral valve is irregular in outline, with subcircular to heart-shaped pedicle area, and ornamented by a few (30 - 35 in Cooper 1973 and 15 - 20 in Bitner et al. 2008), widely spaced, straight or slightly arched, tuberculate radial costellae. On the contrary, the ventral valve of D. borneensis n. sp. is subhexagonal in outline, its pedicle area is subcircular, and its surface is ornamented by numerous (about 180), closely spaced radial costellae without tuberculate appearance. Having a generally pale yellow, pale straw colour, some colour patterns can be observed on the dorsal valves, in the form of a more pronounced concentric pattern and a slightly uncertain radial pattern. Some specimens show a lighter, almost white colour around the apex (Fig. 2 D, H), followed by a less defined central part, and alternating concentric lighter and darker bands at the edges of the specimens (Fig. 2 A, H). Darker patches with irregular outlines are also observed in the middle part of the Figure 2 D specimen. The darker colour is mostly confined to the interspaces of the costellae, the costellae themselves being uniformly lighter in colour (Fig. 2 A, D, H); a similar observation was mentioned by Ishizaki & Shiino (2023) for Discradisca sp. cf. D. stella. In another specimen, the apex area is orange, turning dark brown towards the shell margin (Fig. 2 G). The inner side of the dorsal valves also shows lighter (yellowish) and darker (brownish) irregular concentric bands at the shell margin (Fig. 2 B, I), but some valves also show a more indistinct yellow-orange radial pattern (Fig. 2 E). Surface of muscle attachment scars is brightly coloured, almost white (Fig. 2 B, E). On the ventral valve, the pedicle area is white, with a narrow dark brown band marking the outer margin on the external side. The area outside the pedicle area is pale brown, with a much less distinct concentric pattern at the edge than in the dorsal valve. On the internal side, the colours are brighter and the costellae are more defined. Here the concentric pattern is also more visible, but sometimes the concentric colour pattern is not continuous. The discolouration again occurs in the interspaces of costellae, but here the costellae are darker than the colour pattern, unlike in the dorsal valve. The shells adapt to the surfaces to which they live attached, resulting in irregular shapes. The animals have been found attached to rocks and shells from the intertidal zone to – 20 m. They occur on hard substrates in siliciclastic depositional environments (such as rocky intertidal at Tanjong Lobang and the shipwrecks resting on sandy bottom, both near Miri, Sarawak, Malaysia), in shallow water coral areas (Labuan and Kota Kinabalu, both Sabah, Malaysia) and subtidal coral banks (Outer Reef, Grouper Patch, Azam’s Place near Miri, Sarawak, Malaysia). Several specimens were found alive, but none was preserved as at the time (1992 - 1997) locally methanol was not available to the general public. From a single large specimen (collected from intertidal rocks in the southern part of Tanjong Lobang, Miri, Sarawak, Malaysia), besides the dorsal valve, the corneous thin ventral valve was preserved, which according to the field sketch was present between the animal and the rock on which it lived (Fig. 4). The dorsal valves provide a substratum for a variety of epibionts, including barnacles, bryozoans, calcareous algae and other organisms. No single specimen was seen with substantial overgrowth.	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFA0FFF7FF657E30FEB0FAB5.taxon	description	(Fig. 5)	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFA0FFF7FF657E30FEB0FAB5.taxon	materials_examined	TYPE MATERIAL ILLUSTRATION. — 2021 online photographs, syntypes National Zoological Collection (Zoological Survey of India); 2021 online photographs, syntypes RBINS Virtual Collections, Brussels.	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFA0FFF7FF657E30FEB0FAB5.taxon	description	ORIGINAL DESCRIPTION (Preston 1908). — “ Shell semicorneous, depressedly conical, irregularly subquadrate, pale yellowish brown, sculptured with fine radiating transverse ribs crossed by concentric striae, presenting a very finely cancellate appearance; edge of peristome finely crenulate; apex simple, placed slightly to one side: anterior end of shell shortened; posterior end broadly produced. Altitude 2 mm. Diam, major 9, minor 7.75. ” EMENDED DESCRIPTION. — Outline of subcircular dorsal valves (8 - 9 mm in diameter) more irregular than in D. borneensis n. sp. Asymmetrically low-conical in profile (3 mm high) (Figs 5 D, G), posterior slope straight, anterior slope slightly convex (Fig. 5 G). Smooth apex in subcentral position (Figs 5 B, E), shifted posteriorly. Apex area eroded on both specimens (details of larval shell and brephic shell cannot be observed well); larval shell (protegulum) apparently smooth. External surface of dorsal valve with numerous (140 - 145) fine, well-pronounced but slightly irregular, tuberculate radial costellae and relatively strong, concentric growth lines. Costellae continuous and densely spaced, interspaces wider than ridges. Small irregular granules on radial costellae, more pronounced on RBINS specimen (Fig. 5 E). Number of costellae increasing by intercalation towards the edges (Figs 5 B, E). RBINS specimen bearing traces of survived physical damage or predation, where the growth lines blurred and radial costellae broken (Figs 5 E, G). Shell edge finely crenulate (Fig. 5 B, E). Internal side smooth, but traces of external costellae on the internal surface, especially along the edge of valves (Figs 5 C, F). On lectotype muscle scars covered by thin white chalky deposit; on RBINS specimen lighter colour of ring-shaped muscle scars faintly visible. Shell of variable, generally pale straw colour. Lectotype lighter in colour around the apex, with alternating concentric bands of lighter and darker colours towards the edge (Fig. 5 B).	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFA0FFF7FF657E30FEB0FAB5.taxon	distribution	DISTRIBUTION. — India, Sri Lanka, Philippines, Persian Gulf, and Indonesia.	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
4F308799FFA0FFF7FF657E30FEB0FAB5.taxon	discussion	REMARKS The species has long been considered a mollusc after the original description by Preston (1908), but subsequent authors placed it in various genera belonging to widely differing families of gastropods: Acmaea Eschscholz, 1833 (Acmaeidae Forbes, 1850, Patellogastropoda Lindberg, 1986) (Preston 1908); Potomacmaea Peile, 1922 (Lottiidae J. E. Gray, 1840, Patellogastropoda Lindberg, 1986) (Grant 1937); Gadiniidae J. E. Gray, 1840 (now considered a junior synonym of Trimusculidae J. Q. Burch, 1945, Heterobranchia Burmeister, 1837) (Lindberg 1990); Pilosabia Iredale, 1929 (Hipponicidae Troschel, 1861, Caenogastropoda L. R. Cox, 1960) (Ravinesh et al. 2021). Syntypes of Acmaea semicornea were deposited in the Indian Museum in Kolkata (India) and subsequently moved to the National Zoological Collection (Zoological Survey of India). The specimen illustrated online appears to be the same as the specimen figured by Preston and is here selected as lectotype. Three juveniles, also from the Andaman Islands and seen by Preston are in the Natural History Museum (London, UK; NHM 1888.12.3.1 - 3), considered paratypes by Lindberg (1990: 314) but not assigned such status in the original paper (Preston 1908). Two additional syntypes were apparently exchanged with Dautzenberg and are kept in RBINS (Brussels, Belgium, RBINS / Dautz-Types / 525910). All these syntypes are here assigned as paralectotypes. The semicornea specimens published as gastropods are all dorsal valves; there is no information about the ventral valve in these materials. The dorsal valve characteristics of semicornea fit into the variation range of Discradisca indica Dall, 1920 (compare Dall 1920; Cooper 1973; Bitner et al. 2008).	en	Dulai, Alfréd, (Han) Raven, J. G. M. (2026): New data on Discradisca Stenzel, 1964 (Brachiopoda, Discinoidea) from South and South-East Asia: description of D. borneensis n. sp. from NW Borneo and taxonomic status of D. semicornea (Preston, 1908). Zoosystema 48 (12): 323-334, DOI: 10.5252/zoosystema2026v48a12
