Corallistes floreana, Schuster & Cárdenas & Pisera & Pomponi & Kelly & Wörheide & Erpenbeck, 2018

Schuster, Astrid, Cárdenas, Paco, Pisera, Andrzej, Pomponi, Shirley A., Kelly, Michelle, Wörheide, Gert & Erpenbeck, Dirk, 2018, Seven new deep-water Tetractinellida (Porifera: Demospongiae) from the Galápagos Islands - morphological descriptions and DNA barcodes, Zoological Journal of the Linnean Society 184, pp. 273-303 : 282-283

CORALLISTES FLOREANA SP. NOV.

( FIGS 6, 7; TABLE 2)

Diagnosis: Corallistes with smooth dichotriaenes in a broad range of sizes (93–558 µ m rhabd; 72–272 µ m cladome) and amphioxeas of 327–887 µ m length; choanosomal megascleres are tuberculate dicranoclone desmas, about 211–345 µ m diameter.

Type material: Holotype: HBOM 003 :02000, Coll. JSL-I dive 3901 [16 October 1995, Galápagos, N-Side 1.25 NM NW of Cormorant Point, Floreana Island, Santa Maria , 01°12 ′ 5.88 ″ S, 90°26 ′ 9.96 ″ W, 121 m].

Comparative material: Corallistes isabela HBOM 003:02013 (203 m), Galápagos, Santiago Island, 0°11 ′ 29 ″ S, 90°34 ′ 58 ″ W, Coll. JSL-I dive 3927, identified by A. Schuster .

Type locality: Floreana Island , Galápagos Islands (121 m) ( Fig. 1) .

Distribution: Only known from type locality.

Habitat: Attached to hard substratum (121 m).

Description: Morphology, a shallow bowl with a slightly folded or indented margin, or ear-shaped, walls about 5–6 mm thick with rounded margins ( Fig. 6A, B), holotype, about 8 cm diameter, about 6 cm high ( Fig. 6A, B). Surface, uneven, partly covered with algae, coral and shell fragments, bundles of projecting spicules trap sediment on the upper surface, otherwise the surface is smooth, oscules are not visible ( Fig. 6B). Texture, stony. Colour, beige in life ( Fig. 6A), light brown to cream in ethanol preservative ( Fig. 6B). Ectosomal skeleton, irregular, composed of dichotriaene cladomes, aligned tangentially to surface with rhabdome pointing in towards choanosome ( Figs 6C, D, 7J, K), with scattered microscleres ( Fig. 7B, E). Choanosomal skeleton composed of zygosed dicranoclone desmas ( Fig. 6E, F) between which are large subdermal spaces and scattered microscleres ( Fig. 7C–G). Megascleres, desmas, triaenes, microxeas; dicranoclone desmas, 211–354 × 176– 261 µ m (N15). Dichotriaenes in a large size range with long and short rhabdomes: smallest dichotriaenes, cladome, 72– 82 –106 µ m, rhabdome 93– 110 –130 µ m (N25), largest dichotriaenes, cladome, 130– 186 – 278 µ m, rhabdome, 208– 314 –558 µ m (N25) ( Figs 6D, 7J, K); microxeas, 327– 630 –887 × 4.8– 6.6 –10.8 µ m (N6) ( Fig. 7H, I). Microscleres, metasters with long, pointed, acanthose rays, 16.8– 29.9 – 42 × 14.3– 23.6 –30.7 µ m (N21), amphiasters and spirasters with short, pointed, microspined rays, 8.2– 11.9 –15.1 × 6.4– 10.1 –13.5 µ m (N21).

Etymology: Named after the type locality, Floreana Island.

DNA barcodes: We sequenced COI, 28S (C1-D2) and 18S (1303 bp) from the holotype; GenBank accession numbers: COI KY652816 , 28S KY652784 , 18S KY652833 . SBD record no. 1715.

Remarks: Corallistes floreana sp. nov. resembles C. isabela , previously described from the Galápagos Islands, but there are notable differences in the size and ornamentation of the megascleres. The dicranoclone desmas in C. floreana sp. nov. are smaller and tuberculate rather than knobbed as in C. isabela ( Table 2). Furthermore, the alternating sizes of the C. floreana sp. nov. cladomes differ by their ratio from C. isabela ( Table 2). Amphiasters / spirasters are smaller in size as well ( Table 2). Pairwise sequence differences of 1.2% (28S) and 0.8% (COI) between C. floreana sp. nov. and C. isabela (HBOM 003:02013) further confirm integrity of these two species.