Indiella ridgenensis, Sautya, Sabyasachi, Tabachnick, Konstantin R. & Ingole, Baban, 2011

Sautya, Sabyasachi, Tabachnick, Konstantin R. & Ingole, Baban, 2011, A new genus and species of deep-sea glass sponge (Porifera, Hexactinellida, Aulocalycidae) from the Indian Ocean, ZooKeys 136, pp. 13-21 : 15-16

Indiella ridgenensis sp. n. Figs 24

Etymology.

The species name is derived from its type locality, the ridge (Carlsberg Ridge) habitat.

Material examined.

Carlsberg Ridge, Indian Ocean: 'Akademic Bois Petrov’ station. DR-13, 07°00.466'N, 59°56.295'E, 2589 m, November 2009.

Holotype.

NIO/BOD/5-H/2011, stored in ethanol. NIO/SPONGE/DR-13/H, slide, stored in ethanol. IORAS (Institute of Oceanology of Russian Academy of Sciences) 5/2/ NIO/BOD/5-H/2011 (slides).

Paratypes: NIO/BOD/5-P1, NIO/BOD/5-P2, NIO/BOD/5-P3, stored in ethanol. NIO/SPONGE/DR-13/Pi, NIO/SPONGE/DR-13/Pii, NIO/SPONGE/DR-13/Piii, slides. IORAS NIO/BOD/5-P1, NIO/BOD/5-P2, NIO/BOD/5-P3, slides.

Description.

Body: The sponge consists of small, lamellate, thin fragments. The holotype is a flat fragment approximately 40 × 17 mm about 1 mm in thickness (Fig. 2i). Paratypes are similar: Pi is a lamellum 20 × 25 mm (Fig. 2ii); Pii is 30 × 20 mm (Fig. 2iii); Piii is 50 × 45 mm (Fig. 2iv). From the dermal side numerous epirhyses are observed, they are 1.3 - 1.5 mm (Fig. 4C) in diameter and penetrate about a half of the wall thickness.

Spicules framework is seems to be constructed of different elements: regular, longitudinally directed dictyonal strands, located mostly in the vicinity of the atrial surface (approximately 4 layers) and irregular hexactins fused to each other and to the regular elements at points of mutual contacts, at all levels of the wall thickness. All framework surfaces are covered by very small spines, the free outer ray ends are conically pointed. The dictyonal strands are easily observed, they have diameter 0.09-0.12 mm, beams between the strands are 0.03-0.07 mm in diameter. Free rays of the dictyonal strands are protruded atrially. The meshes between the dictyonal strands and their connecting beams are rather regular, usually rectangular, 0.3 –0.5×0.5– 0.8 mm. Adjacent hexactinic spicules located among the dictyonal strands are irregularly and sparsely distributed among their meshes, they are connected to the framework by a single ray (small hexactins with rays 0.07 –0.12/0.003– 0.006 mm) and often at points of mutual contact (large hexactins with rays about 0.5/0.012-0.018 mm). The meshes there are very irregular and of different sizes. The dictyonal strands may be also observed in the vicinity of dermal surface but due to numerous epirhyzes, they are not straight as those from the atrial surface.

Loose spicules: dermal and atrial pentactins are similar to each other, they always have a rudiment about 0.02 mm long instead of the ray directed outside the body, rough surface, their outer ends are clavate, rounded, lanceolate or sometimes conically pointed. Tangential rays of dermal pentactins are 0.102-0.432 mm long (Table 1), the ray directed inside the body is 0.048-0.258 mm long (Table 1), the diameter of these rays is 0.002-0.009 mm. Tangential rays of atrial pentactins are 0.078-0.372 mm long, ray directed inside the body is 0.036-0.342 mm long (Table 1), the diameter of these rays is 0.004-0.009 mm.

Microscleres are stellate discohexasters only, with 8-14 secondary rays. The diameter of the discohexaster is 0.025-0.046 mm, their primary rosette is 0.006-0.018 mm in diameter (Table 1).

Remarks.

Since all these fragments of the holotype and of paratypes were collected from the same station, there is a great probability that they belong to a single specimen.