Sycettusa zanzibaris ( Jenkin, 1908 )

Van, Rob W. M. & De, Nicole J., 2018, Calcareous sponges of the Western Indian Ocean and Red Sea, Zootaxa 4426 (1), pp. 1-160 : 125-128

publication ID

https://doi.org/ 10.11646/zootaxa.4426.1.1

publication LSID

lsid:zoobank.org:pub:18929E20-5296-4458-8A8A-4F5316A290FD

DOI

https://doi.org/10.5281/zenodo.5966758

persistent identifier

https://treatment.plazi.org/id/386CC616-DC0E-A54E-FF67-8ABEFBCCFC5E

treatment provided by

Plazi

scientific name

Sycettusa zanzibaris ( Jenkin, 1908 )
status

 

Sycettusa zanzibaris ( Jenkin, 1908) View in CoL

Figs 77a–g View FIGURE 77 , 78a–i View FIGURE 78

Grantessa zanzibaris Jenkin, 1908: 448 View in CoL , figs 98–102; Burton 1959: 180.

Material examined. ZMA Por. 11491, Seychelles, Bird Island, off E coast, 3.7167°S 55.2167°E, reef, depth 3 m, snorkeling, coll. R.W.M. van Soest, field nr GoogleMaps . NIOP-E stat. 717/ 08, 20 December 1992; ZMA Por. 11566, Seychelles, Amirantes, Île Desnoeufs platform, outer slope, 6.2167°S 53.0167°E, depth 12–15 m, scuba, coll. R.W.M. van Soest, field nr GoogleMaps . NIOP-E stat. 738/ 22, 2 January 1993; ZMA Por. 11568, Seychelles, Amirantes, N of D’Arros Island, 5.4°S 53.3167°E, depth 45–55 m, on rhodolite bottom, dredge, coll. R.W.M. van Soest, field nr GoogleMaps . NIOP-E stat. 752/ 13, 26 December 1992; ZMA Por. 12438, Seychelles, Amirantes, N of D’Arros Island, 5.4°S 53.3167°E, depth 45–55 m, on rhodolite bottom, dredge, coll. R.W.M. van Soest, field nr GoogleMaps . NIOP-E stat. 752/ 11, 26 December 1992.

Description. Masses of short tubes ( Figs 77a–b View FIGURE 77 ), beige-white to light brown in situ and on deck, pale transparent white in alcohol. The specimens have a quite characteristic glassy slippery appearance in alcohol. Size of largest mass up to 2 cm in lateral expansion, 1–2 cm high. Individual tubes up to 5 mm high, 3–4 mm in diameter, with the oscule about 1 mm diameter and surrounded by a thin collar. Consistency cartilaginous.

Aquiferous system. Syconoid.

Skeleton. ( Figs 77c–g View FIGURE 77 ) Inarticulate ( Figs 77c–d View FIGURE 77 ). The cortical skeleton ( Fig. 77e View FIGURE 77 ) is a mixture of tangential triactines and short banana-shaped diactines, carried by the shortest paired actine and unpaired actine of subcortical pseudosagittal triactines. The inarticulate skeleton is made up of the longer actines of the subcortical pseudosagittal triactines and the unpaired actines of subatrial triactines. The atrial skeleton ( Fig. 77f View FIGURE 77 ) consists of the paired actines of the subatrial triactines supported by two types of tetractines, smaller with all actines of almost similar length and thickness, and larger with enlarged apical actines protruding far into the atrial lumen. The small oscular collar ( Fig. 77g View FIGURE 77 ) is formed by giant diactines, trichoxeas, triactines (similar to the subatrial triactines) and regular tetractines with a short apical actine.

Spicules. ( Figs 78a–i View FIGURE 78 ) Diactines, trichoxeas, cortical triactines, pseudosagittal triactines, sagittal triactines, tetractines.

Giant diactines( Fig. 78a View FIGURE 78 ), fusiform 402– 667 – 1100 x 12 – 20.6 –29 µm.

Trichoxeas (Fig, 78b), invariably broken, fragments 240–330 x 2–3 µm.

Banana-shaped diactines ( Fig. 78c View FIGURE 78 ), curved, asymmetrical, 141– 162 –204 x 7 –8.1–9 µm.

Cortical triactines ( Figs 78d View FIGURE 78 ), equiangular and equiradiate or more often with all actines of slightly different length or slightly sagittal, actines 84– 103 –126 x 6 – 8.3 –10 µm.

Pseudosagittal triactines ( Figs 78e View FIGURE 78 ), with middle actine straight or gently curved, and shortest actine with a characteristic angular curve, longest actines 81– 146 –183 x 6 – 6.9 –8 µm, middle-sized actines 73– 106 –138 x 6 – 6.6 –9 µm, shortest (unpaired) actines 59– 88 –111 x 6 – 6.8 –8 µm.

Subatrial triactines ( Figs 78f View FIGURE 78 ) (and triactines of the oscular collar), sagittal, almost T-shaped, unpaired actines

151– 179 –210 x 8 – 9.8 –11 µm, paired actines 81– 92 –105 x 7 – 8.2 –9 µm. Small equiradiate tetractines ( Fig. 78g View FIGURE 78 ), equiangular, but not equiradiate, with clear position of unpaired actines, paired actines and curved apical actines; unpaired actines 54– 69 – 84 x 5 – 6.3 –8 µm, paired actines 76– 97 –111 x 6 – 6.7 –7 µm, apical actines 37– 56 – 84 x 5 – 5.7 –7 µm.

Larger atrial tetractines ( Fig. 78h View FIGURE 78 ), unpaired and paired actines similar in length, 62– 95 –112 x 5 –6.6–8 µm, apical actines long, curved or sometimes slightly crooked, 105– 229 –432 x 6 – 7.1 –9 µm.

Tetractines of the oscular collar ( Fig. 78i View FIGURE 78 ), resembling subatrial sagittal triactines but with small curved apical actine; unpaired actines, 81– 112 –126 x 7 – 7.4 –9 µm, paired actines 84– 96 –111 x 7 –7.6–9 µm, apical actines 22– 43 – 61 x 5 – 5.7 –7 µm.

Distribution and ecology. Seychelles, Zanzibar, shallow water down to 55 m. Burton (1959) reported this species from the Southern Red Sea, but provided no description.

Remarks. The presence of tetractines and the characteristic angular curve of the unpaired actines of the pseudosagittal triactines distinguish this species from all other Sycettusa species of the Western Indian Ocean.

Voigt et al. (2012) used ZMA Por. 11566 for their study of the phylogeny of Calcarea (identified as S. cf. simplex ). Voigt et al. ’s sequence was compared with our own from ZMA Por. 11568 (see Fig. 74 View FIGURE 74 ), and in an alignment trimmed to a length of 403 sites, we found two differences. Our partial 28S sequences of Sycettusa zanzibaris grouped in the same clade together with New Caledonian S. tenuis Borojević & Klautau, 2000 (downloaded from the Sponge Barcode Project site) away from mainstream Sycettusa species and closer to Grantessa species. S. zanzibaris and S. tenuis were found to exhibit 3 differences in the 403 sites alignment, so these are probably closely related. Borojević & Klautau 2000 (p. 198) stated in their remarks that S. tenuis was ‘certainly close to Sycettusa simplex ( Jenkin, 1908) ’, but as these authors admit, S. simplex has no tetractines (cf. Jenkin’s description of the atrial skeleton and spicules on p. 449). Remarkably, they did not point out that S. zanzibaris rather than S. simplex is the closer species.

The position of the group of species comprising Ute , Uteopsis and Grantessa grouped in our phylogeny of Fig. 3 View FIGURE 3 within the larger clade of Sycettusa species remains unclear for the moment.

ZMA

Universiteit van Amsterdam, Zoologisch Museum

Kingdom

Animalia

Phylum

Porifera

Class

Calcarea

Order

Leucosolenida

Family

Heteropiidae

Genus

Sycettusa

Loc

Sycettusa zanzibaris ( Jenkin, 1908 )

Van, Rob W. M. & De, Nicole J. 2018
2018
Loc

Grantessa zanzibaris

Jenkin, 1908 : 448
Burton 1959 : 180
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