Vetulina tholiformis, Schuster & Pisera & Kelly & Bell & Pomponi & Wörheide & Erpenbeck, 2018

VETULINA THOLIFORMIS View in CoL SP. NOV.

( FIGS 2G–J, 4A–F, 5A–C)

Diagnosis: Dome-shaped Vetulina with a thick, steepsided body and circular to oval base and an osculum opening (1–4 mm in diameter) on the apex of the sponge. Microscleres are styles and (sub)tylostyles.

Holotype: HBOI 30 -X-96-2-003: JSL-I dive 2799, SW Grand Bahama Island , lithoherm (deep-water c a r b o n a t e m o u n d), B a h a m a s, 2 6° 3 7′2 7.2 3″ N, 78°58′48.83″W, 428 m, October 1996.

Paratypes: HBOI 11 -XI-02-3-011: JSL-I dive 4500, Eleuthera, Weymyss Bight , Bahamas, 24°45′53.46″N, 76°19′21.58″W, 427 m, November 2002 GoogleMaps . 19-XI-98-1- 005: JSL-I dive 4109, Rum Cay, South Coast of Port Nelson , Bahamas, 23°37′24.42″N, 74°50′4.74″W, 440 m, November 1998 GoogleMaps . 13-XI-02-1-009: JSL-I dive 4503, Crooked Island, NW Tip, Bahamas, 22°40′0.66″N, 74°21′7.13″W, 367 m, November 2002 GoogleMaps .

Type locality: Northern Caribbean, Bahamas. SW Grand Bahama Island lithoherm (26°37′27.23″N, 78°58′48.83″W), 428 m ( Fig. 1A) GoogleMaps .

D i s t r i b u t i o n: B a h a m a s (2 6 ° 3 7 ′ 2 7. 2 3 ″ N, 78°58′48.83″W), 428 m; Bahamas, 22°49′– 26°37′N , 74°21′– 78°58′W, 367– 440 m.

Description: Dome-shaped sponge with a thick, steepsided body and circular to oval base ( Fig. 2G–J). Surface smooth or with several oval depressions ( Fig. 2G–J). The entire plain base of the sponge is attached to the hard substratum ( Fig. 2G–J). Dimensions of the spherical–bulbous sponge are 0.7 cm × 2.5 cm. Circular osculum, flush with the surface, 1–4 mm in diameter, located apically or laterally on the sponge ( Fig. 2G–J). Outer surface smooth; pores not visible. Colour in life is pale yellow, and yellowish brown ( Fig. 2G, I) to dark brown in ethanol.

Choanosomal skeleton consists of very dense sphaeroclone desmas (150–300 µm in diameter).

Megascleres are sphaeroclones; the centre from the outer choanosomal part has spinose root-like outgrowth ( Fig. 4E, F), whereas the inner part shows lower tubercles with low, smooth tubercled rays. Three to five main rays branch from the centre and connect with the upper centre part of adjacent desmas, building up the skeleton network ( Fig. 4A–D). Rarely, immature desmas are visible, showing a typical hollow of 20–25 µm in diameter instead of a globular centre ( Fig. 4E).

Microscleres are styles with mucronate tips ( Fig. 5A), subtylostyles with a slight swelling on the upper part of the shaft (= polytylote; Fig. 5B) and tylostyles. Both style types are sparsely distributed (perpendicular) in the ectosomal part and concentrated around the osculum openings (not shown).

Etymology: From Greek tholos, meaning a beehive tomb or domed tombs, which describes the oval dome-shaped gross morphology of the sponge.

surface. Wide and tiny vein-like channels radiate from the osculum. Megascleres are sphaeroclonar desmas. Microscleres are styles and diverse subtylostyles.

Holotype: NIWA 109682 View Materials , BSPG 8020 View Materials , 0CDN 3443- A, USNM 1470701 About USNM : Davao, north side of Talikud Island . Deep inside crevices. Local name: ‘ Angels Cove’, Philippines, 6°56′43″N, 125°40′56″E, 7–12 m. Collected by Dr Patrick L. Colin, Coral Reef Research Foundation, Republic of Palau, March 1996. GoogleMaps

DNA barcodes: In the present study, we sequenced partial cox1 (‘Folmer’ fragment), ITS and partial 28S (C1–D2 fragment) of the following specimens: HBOI 30-X-96-2-003, 19-XI-98-1-005, 13-XI-02-1-009 and 11-XI-02-3-011. Sequences from each of the gene fragments were identical; partial 18S for HBOI 19-XI-98-1-005, 13-XI-02-1-009 and 11-XI-02-3-011.

Remarks: This new species differs from V. stalactites , V. rugosa and V. indica , which form foliose vases and cups ( Pisera et al. 2017), by having a dome-shaped external growth form instead of being flabellate vase to cup shaped ( Fig. 2). The choanosomal sphaeroclones are very similar to V. rugosa , V. indica and V.stalactites , and differ only in minor details, such as tuberculation and arborescent outgrowth density of the desma centre. In terms of microsclere composition, the new species differs from V. rugosa , V. indica and V. stalactites in that rare stubtylostyles and tylostyles were detected aside from styles. Vetulina tholiformis sp. nov. differs from the new species V. incrustans sp. nov. (for description, see next subsection) by being thinly (vs. thickly) encrusting.