Hymeraphia pacifica n. sp.

urn:lsid:zoobank.org:act: 97A04FD1-22EB-4092-B0BC-6AB71CDB01AA

Figure 5

Diagnosis Thin encrusting sparingly hispid and papillate lemon yellow sponge; short tylostyles for the genus.

Etymology The species name refers to its geographic location in the Northeast Pacific which constitutes a geographic range extension from the Northeast Atlantic range of previously described species.

Material Examined Holotype RBCM 018-00148 - 006, Stn NM 269, Anvil Isl, Howe Sd, BC, 49° 32.026’ N / 123° 17.420’ W, coll. N. McDaniel, 19 Aug 2011, 18 m depth, one specimen.

Description

External (Figure 5A) Holotype RBCM 018-00148-006. Encrusting, 6 x 8 cm x 1 mm; surface sparingly hispid, micropapillose; papillae 1 mm high by 1–2 mm diameter, oscula at ends, 0.5 mm diameter. Colour lemon yellow. Consistency easily torn, compressible. Spicules protrude 100 to 300 µm on average; maximum to 1800 µm.

Skeleton (Figure 5B, C) Ectosome composed of thin style brushes around the subtylostyles where they project from the surface. Choanosome packed with acanthostrongyles from the sponge base to the surface. At the surface most acanthostrongyles are oriented with heads down and acanthose tips outward. Long subtylostyles are embedded in the top of the choanosome and project beyond the surface. Tylostyles are scattered throughout the choanosome.

Spicules (Figures 5D, E, F and G) Subtylostyles, ectosomal styles, tylostyles, acanthostrongyles. Subtylostyles (to tylostyles) (Figure 5D) thin, curved, long apices, flexuous, apices blunt, 1350 (1923) 2295 x 13.0 (20.7) 26.0, (head width) (n=24) uncommon. Ectosomal styles (Figure 5E) thin, curved or flexuous, long blunt-ended apices, 216 (423) 618 x 2.1 (3.2) 5.2 µm. Tylostyles (Figure 5F) tapering from a spherical head to a sharp apex; head may be off centre and may be subterminal, 237 (365) 526 x 26.0 (30.0) 36.4 µm. Acanthostrongyles (Figure 5G) stellate apex; spherical head, 55 (73) 104 x 18.2 (22.6) 33.8 µm.

Distribution Howe Sound., BC 13–18 m depth.

Ecology Forms small encrustations on bedrock. Up to 10 cm in diameter.

Remarks There are four accepted species of Hymeraphia worldwide (de Voogd, et al 2023): the type species H. stylifera Bowerbank, 1864 from the UK, two from Northern Ireland, both described by Picton & Goodwin (2007) H. breeni Morrow, 2018, H. elongata Morrow, 2018 and H. vaceleti Morrow, 2018 from Ireland. All, except H. vaceleti, were collected from shallow water, all are thin encrusting and variously hispid with a hymedesmioid skeleton. Table 5 compares key characteristics of world Hymeraphia species. Note: in the table acanthostyles with stellate apices and acanthotylostrongyles are equivalent.

Hymeraphia pacifica n. sp. is a zoogeographic range extension for the genus.

Hymeraphia breeni has one type of tylostyle versus two present in H. pacifica and acanthostyles are limited to the basal area. Hymeraphia elongata long tylostyles extend from the base through the surface versus most H. pacifica surface penetrating spicules originate in the subsurface area. Hymeraphia elongata acanthostyles are concentrated on the basal spongin plate. Hymeraphia vaceleti has acanthostyles with strongly bent heads. Hymeraphia pacifica n. sp. is closest to H. stellifera in habitus, skeleton and spicules. However, H. stellifera is not a common shallow water sponge (less than 30 m depth) (Ackers, et al. 2007) and the geographical separation (Northeast Atlantic/ Mediterranean versus Northeast Pacific) make conspecificity unlikely.