Psammochela tutiae, De, Nicole J., 2012

De, Nicole J., 2012, On sand-bearing myxillid sponges, with a description of Psammochela tutiae sp. nov. (Poecilosclerida, Myxillina) from the northern Moluccas, Indonesia, Zootaxa 3155, pp. 21-28 : 22-27

Psammochela tutiae sp. nov.

( Fig. 1A –D, 2A–E)

Material examined. Holotype RMNH POR. 5490, Indonesia, Halmahera mainland Tanjung Sidangolo, stat TER.020, N 0°53'39.6", E 127°29'28.1", 05-11-2009, depth 27 m. Fieldnr #TER20/ 051109 /241, coll. Y. Tuti Paratypes: RMNH POR. 5509, Indonesia, Halmahera, Ternate Sulamadah I., stat TER.022, N 0°52'3.6", E 127°19'33.1", 06-11-2009, depth 20 m, Fieldnr #TER22/ 061109 /260, coll. K. van Egmond; RMNH POR. 5475 Indonesia, Halmahera, Tidore SW of Tobala, stat TER.019, N 0°44'56.6", E 127°23'13.5", 04-11-2009, depth 30 m, Fieldnr #TER19/ 041109 /226, coll. K. van Egmond.

Other Material examined: Psammochela rigida ( Bowerbank, 1875) , unreg. type BMNH (as Halichondria rigida ). Psammochela fibrosa ( Ridley, 1884) , unreg. type BMNH (as Phoriospongia fibrosa ), Torres Strait, Northern Great Barrier Reef. Psammochela elegans Dendy, 1916 , Lectotype BMNH 1920.12.9.36, Indian Ocean, India. Psammochela chaliniformis (Dendy, 1896) , BMNH 1886:12:15:341 (as Dysidea chaliniformis ). Psammochela psammodes ( Hentschel, 1911) , Holotype ZMB 4414 (as Desmacidon psammodes ). Psammochela psammodes , ZMA POR. 9463, Snellius II, 14.10.1984, Indonesia, Sulawesi, NE Take Bone Rate, stn. 222, 06°31.5’ S 121°08’ E, 58 m, coll. R.W.M. van Soest. Psammochela elegans , ZMA POR. 9053, Snellius II 16.09.1984, Indonesia, Nusa Tenggara, NE Coast of Sumba, stn. 0 68, 09°57’ S 120°48’ E, light red, sandy bottom with sponges and gorgonians, dredged at 50 m, coll. R.W.M. van Soest.

Description. Shape: The holotype consists of a part of a larger specimen (see fig. 1a and 1b). The specimen is bushy with anastomosing thorny branches with pointy endings. Raised oscules (diameter of 2–5 mm) along one side of the branch every 2–3 cm. The surface is irregularly rugose and smooth in between and the ectosomal reticulation is clearly visible in live and preserved specimens. Colour is pale salmon pink to light orange alive, grayish in spirit. The texture is compressible, brittle.

Skeleton. Ectosomal skeleton consists of a large irregular meshed reticulation outlined by large sand grains, other foreign material and thin strongyles, meshes 0.4–1 cm in diameter with few microscleres in the soft tissue between the fibres. Choanosomal skeleton is an isotropic to irregular reticulation of spicule tracts mixed with foreign material. The mega-and microscleres are obscured by the large size of the foreign materials.

* holotype

Spicules. Thin strongyles (120–155 x 2.5 μm), two sizes of sigmas (I 25–40 μm; II 12.5–20 μm) and spatulate and/or equianchorate chelae (15–20 μm) (see table 1 and fig. 2).

Ecology. Reef slopes and sandy bottom 10–40 m deep.

Geographic distribution. Specimens were found near the island of Ternate, Tidore & Halmahera in the northern Moluccas, Indonesia.

Etymology. Psammochela tutiae is named after Ir. Yosephine Tuti, who collected and photographed the type specimen. She is also acknowledged for all the logistic support provided in the past years to make our biodiversity studies in Indonesia possible.

Psammochela tutiae is characterized by its bushy growth form, thin strongyles and absence of polydentate chelae. Only five other species belonging to Psammochela are presently recognized: P. rigida ( Bowerbank, 1875) from the Strait of Malacca, P. fibrosa ( Ridley, 1884) from NW Australia, P. chaliniformis ( Carter, 1885) from South Australia, P. elegans ( Dendy, 1916) from NW India and P. psammodes ( Hentschel, 1911) from SW Australia. For the present study I re-examined the type specimens of all species and discovered some crucial differences in spicule combination and dimensions deviating from the original descriptions. In addition I examined as comparative material some recent specimens deposited at the Zoological Museum of Amsterdam from Indonesia ( Table 2 & Fig. 3 ). The type specimens of P. elegans and P. chaliniformis have already been depicted and discussed in the recent revision of the classification of sponges (van Soest, 2002a:618, fig.11), however the spicule measurements deviated somewhat from the present ones (see table 2). Psammochela chaliniformis is very different from the other Psammochela species; the megascleres are completely replaced by sand grains and it has only polydentate unguiferate isochelae. These chelae differ subtly from those in other species: the shaft is rather straight and the alae are shorter, more numerous and pointy (fig.3 and Van Soest, 2002a:618, fig.11L). Although Burton specimen source megasclers Sigma I Sigma II Chelae I Chelae II

Anchorate polydentate P. rigida * b Styles 150–175 x 5–6 30–40 11 –15 20–22.5 9– 11 P. fibrosa * a Styles 160–190 32 - 22 - P. fibrosa * b (aniso) Strongyles 140–155 x5 30 –37.5 10–12.5 17.5– 22.5 8– 10 P. chaliniformis * c - - - - 10–12

b - 12.5–17.5 P.elegans * a Styles (strongylote)160 x 5– 33 12 24 12 P. elegans* b Styles 145–160 x 5 30 –37.5 10–15 21.5–22.5 10–12.5 P.elegans * c Styles 160 x 5–7 50 12 24–25 12 ZMA.9053 b Styles 155–180 x 5 30– 35 10 20–22.5 8 P. psammodes* a (aniso) Strongyles 136–166 25–32 10–12 15–17 9– 10 P. psammodes * b (aniso) Strongyles 145–175 x 2.5 25–30 10 –12.5 13–17.5 8–12.5 ZMA.9463 b (aniso) Strongyles 160–175 25–35 12.5–17.5 13–17.5 10–12.5 * type species. Abbreviations: a) original description, b) present study, c) van Soest, 2002

(1934) synonymized P. elegans with P. f i b ro s a, there are some clear differences between the two species. Strangely enough, the original description by Ridley misses the small polydentate chelae and the second category of sigmas. More importantly, the megascleres consist of strongyles and aniso(strongyles) instead of styles ( Fig.3 d). He might have confused alien styles as real megascleres. This species is therefore more related to P. psammodes , but the latter species has smaller microscleres (both sigmas and chelae) and I believe that both P. elegans and P. f i b ro s a are valid species. P. rigida was described by Bowerbank (1875) from the Strait of Malacca as a Halichondria , and he described ‘tension spicule acuate’ (=styles); rather numerous ‘bihamate spicula’ (=sigmas), simple and contort, rare, rather stout ‘bidentate equianchorates’ (=anchorate chelae). The sponge itself is massive and the surface is rugged, uneven and full of ridges and depressions. After examining the type of P. rigida , I conclude that it is very similar to P. elegans and might be a senior synonym of P. elegans . The type localities of both are also close to each other (NE India and Strait of Malacca). The shapes of all type specimens were more or less similar, being massive to irregularly shaped with digitate processes. The ectosomal skeletons of all specimens are also very similar having a tight meshed reticulation of fine sand grains and can therefore not be used as distinguishing character among species ( Fig. 3 G, I). Species belonging to Psammochela are not often observed during biodiversity surveys and the specimens collected during the present study show some variation in the abundance of the microscleres as often observed in some Poecilosclerid sponges. For instance, paratype RMNH POR.5475 has only few chelae in contrast with the other specimens, thus showing the difficulty in identifying this species despite its very characteristic outer morphology. The polydentate chelae were observed in all species, except in P. tutiae sp. nov., and are very numerous in the interstitial membranes of the choanosomal skeleton together with the sigmas. On the other hand, all species have spatulate anchorate chelae, characteristic of the Myxillidae , but these are not very numerous and are hard to detect among the foreign material. A striking similarity is observed in the species Desmapsamma vervoorti Van Soest, 1998 and Psammochela elegans . The species cannot be distinguished by the outer morphology and the same holds true for both the ectosomal and choanosomal skeleton. The only difference lies in the morphology of the spicules; Desmapsamma vervoorti has exclusively hastate oxeote megascleres and two sizes of anchorate chelae and sigmas, but lacks polydentate chelae.

The species, P. fibrosa , P. psammodes and P. tutiae sp. nov. share thin strongyles also observed with Chondropsis , but the present species all have chelae. Looking more closely at Chondropsis , of the 13 species currently assigned to the genus, only Chondropsis australis (as Desmacidon australis ) contains reduced thin isochelae (van Soest 2002b), but this species clearly has an irregular plumose arrangement characteristic for the Chondropsidae . In contrast, the six species united here under Psammochela share the presence of a reticulate skeleton of sand grains and/or of megascleres and anchorate chelae and/or polydentate chelae. In other respects they show considerable differences and their relationships with members of the Chondropsidae and Desmacididae remains unclear. Further research on evolutionary signal contained in different classes of morphological characters (e.g. Hajdu & Van Soest, 1996) coupled to the search for molecular markers may eventually yield more objective criteria for decisions on which competing character states may best direct genus assignments in the sand-sponges.

Figures

FIGURE 1. A, Psammochela tutiae sp. nov., in situ photograph of holotype (photo Y. Tuti); B, preserved specimen (scale bar 5 cm); C, Light micrograph of ectosomal skeleton; D, Light micrograph of choanosomal skeleton.

FIGURE 3. A – B, Unreg. type BMNH Psammochela rigida (Bowerbank, 1875 as Halichondria); C – D, unreg. type BMNH Psammochela fibrosa (Ridley, 1884 as Phoriospongia); E – F, ZMB 4414 Psammochela psammodes (Hentschel, 1911 as Desmacidon) (scale bars SEM, strongyle & style 20 µm; sigma I 10 µm; chelae, sigma II, tip strongyle 5 µm; G – J, Light micrographies. G, Ectosomal skeleton and H, choanosomal skeleton of P. e l e g a n s; I Psammochela psammodes ectosomal skeleton, J, choanosomal skeleton.