Hymeraphia vaceleti, Morrow & Allcock & Mccormack, 2018

Morrow, Christine, Allcock, Louise A. & Mccormack, Grace, 2018, A new species of Hymeraphia Bowerbank, 1864 (Axinellida: Raspailiidae) from a deep-water canyon southwest off Ireland, Zootaxa 4466 (1), pp. 61-68 : 64

Hymeraphia vaceleti sp. nov. Morrow

( Figure 3 a–b )

Material examined: The holotype of Hymeraphia vaceleti sp. nov. ( BELUM Mc2018.1) was collected during cruise CE13008, R.V. Celtic Explorer using the ROV Holland I, southwest off Ireland, 48.583, -10.46, 14/06/2013, 1541 m depth.

Diagnosis: Hymeraphia with markedly bent acanthostyles with a large crown of stellate spines at their distal end.

Holotype description: Thin encrustation measuring 8mm x 5 mm x 1.5 mm, growing on dead Desmophyllum pertusum (Linnaeus, 1758) . Long tylostyles project through surface giving hispid appearance. Consistency soft and compressible. Colour white in ethanol.

Skeleton: Choanosomal skeleton with hymedesmoid arrangement consisting of a basal membrane attached to substratum, bases of echinating acanthostyles and long tylostyles embedded in membrane and arranged perpendicular to it. Long tylostyles protrude a long way through ectosome, surrounded by bouquets of very fine hair-like, ectosomal styles.

Spicules: Tylostyles are long and thin, gently curving and tapering to a fine point, with an asymmetric base, occasionally base is subtylote (125– 690 – 2000 x 7– 10 –12 µm n=3). Echinating acanthostyles have a markedly bent, slightly inflated smooth base, base frequently subtylote. Distal ends of acanthostyles have a large stellate crown composed of approximately 16 spines (acanthostyle length = 57– 69 –83 µm; base = 7– 10 –12.5 µm; crown = 12– 29 –45 µm n =20). Ectosomal styles, very fine and hair-like (340– 415 –460 µm x 1–2 µm n=20). See Fig. 2 for spicule morphology and Table 2 for spicule dimensions.

Etymology: The specific epithet vaceleti is given in honour of our dear friend and colleague, Dr. Jean Vacelet, for the friendship and encouragement he has consistently shown and for his overwhelming contribution to sponge science.

Remarks: Hymeraphia vaceleti sp. nov. differs from other species of Hymeraphia by the distinctive acanthostyles which are shorter than those of the other congeners and have a much larger stellate crown of spines. The shaft of the acanthostyle is markedly bent just above the tylote base ( Table 1).

Figures

FIGURE 2. Hymeraphia vaceleti sp. nov. holotype: A, SEM of tylostyles; B, SEM of acanthostyles.

FIGURE 3. SEM of acanthostyles in Hymeraphia spp.: A, H. stellifera Holotype BMNH 1877.5.21.460; B, H. breeni Holotype BELUM Mc2486; C, H. elongata Holotype BELUM Mc3129; D, Hymeraphia vaceleti sp.nov. Holotype BELUM Mc2018.1.