Clathria (Clathria) priestleyae Goodwin & Berman & Hendry 2019, sp. nov.

Clathria (Clathria) priestleyae sp. nov.

(Figure 14)

lsid:zoobank.org:act: 7FE528FB-040A-4C14-9A73-A4695DF0E64B

Specimens. Holotype: BELUM. Mc 2015.638 Rocks near San Martin Islands (65°41.297’S, 65° 20.091’W), depth 6–21 m; collected by C. Goodwin and E. Priestley, 17/02/2015.

Paratypes: BELUM. Mc 2015.692, BELUM.Mc2015.703 and BELUM. Mc 2015.713 Vieugue Island (65°38.758’S, 65° 12.540’W), depth 10–22 m; collected by C. Goodwin and E. Priestley, 23/02/2015; BELUM. Mc 2015.721 Port Charcot, Booth Island (65°03.853’S, 64° 01.868’W), depth 6–16 m; collected by C. Goodwin and E. Priestley, 23/02/2015. BELUM. Mc 2015.758 Paradise Bay Wall (64°53.841’S, 62° 52.391’W), depth 14–21 m; collected by C. Goodwin and E. Priestley, 24/02/2015.and BELUM. Mc 2015.775 Paradise Bay Wall (64°53.841’S, 62° 52.391’W), depth 10–24 m; collected by C. Goodwin and E. Priestley, 25/02/2015.

Comparative material examined. Clathria pauper Brondstedt, 1927. BMNH 30.11.5.2a (tissue section and spicule preparation). Labelled ‘N of Discovery Islet from type’.

Etymology. Named after Emily Priestley who was an invaluable member of the expedition dive team.

External morphology. In situ appearance (Figure 14A): Pale yellow encrusting sponge forming patches of variable size (5–> 20 cm) on bedrock. Surface covered with spiky projections up to 2 cm in length, these are sometimes branched. The projections are cored by fibres of spicules which are visible through the projection as a central core.

Preserved appearance. Fairly soft brown basal cushion with projecting, tapering spikes, up to 1 cm in length. Surface velvety, finely hispid.

Skeleton (Figure 14B): In the basal cushion the choanosomal skeleton is an irregular plumo-reticulation of thick ascending fibres of primary styles (up to 20 spicules thick) which are echinated by the acanthostyles, joined by thinner secondary tracts cored by 2–3 primary styles. In the spiky surface projections, a thick ascending fibre of principal styles (up to 20 spicules thick) cores the centre of the projection. Thinner fibres of 2–3 principal styles, heavily echinated by acanthostyles, lead up to the surface at 45° angle to the central fibre. Brushes of sub-ectosomal styles join these at the surface. Microscleres are scattered throughout the tissue.

Spicules: Measurements from BELUM.Mc2015.638.

Principal styles (Figure 14C): 430(802)1105 by 14(19) 25 µm. Large smooth styles which are often slightly curved.

Subectosomal styles (Figure 14D, E): 297(375)440 by 7(9) 11 µm. Tylote head which is spined with a few large spines.

Acanthostyles (Figure 14F): 121(146)168 by 8(11) 21 µm. Entirely spined with fairly large spines.

Thin toxas (Figure 14G): 154(176) 213 µm.

Oxhorn toxas (Figure 14H): 54(69) 103 µm.

Remarks. We have assigned this species to Clathria (Clathria) rather than one of the other seven subgenera on the basis of the lack of differentiation between the axial and extra-axial regions of the choanosome and the presence of a reticulate skeleton, and only a single category of auxillary styles (Hooper 2002b). Although the species has an appearance similar to C. (Axosuberites) rosita Goodwin, Brewin & Brickle, 2012 this subgenus has a distinctive extra-axial skeleton and lacks echinating megascleres (Hooper, 2002b). Of the 29 species present in the Antarctic and adjacent regions only two, C. (C.) lissosclera Bergquist & Fromont, 1988 and C. (C.) pauper Brøndsted, 1927, possess two distinct categories of toxa.

Clathria lissosclera can be distinguished as its megascleres are much smaller (choanosomal styles 170–190 µm and echinating acanthostyles 85–110 µm). Clathria pauper was originally described as having no microscleres (hence the name). Brøndsted (1927) describes basally spined acanthostyles up to 650 by 20 µm, as well as entirely spined acanthostyles up to 250 by 12 µm, and no microscleres. Hooper (1996) re-examined a fragment of the holotype (BMNH1930.11.5.2) and noted that toxas were in fact present. He gives the spicule dimensions as: principal styles with rounded smooth or microspined bases 372(606)810 by 11(15.8) 21 µm; Subectosomal styles 352(481)590 by 3(7.6) 10 µm; Echinating acanthostyles, subtylote with heavily spined base and lighter spined shaft 219(293)384 by 10(12.3) 15 µm; smaller evenly spined acanthostyles 92(148)183 by 5(8.4) 11 µm; Accolada toxas 93(139.5)185 by 0.8(0.9) 1.5 µm; wing-shaped toxas 31(45.5)52 by 1.5(1.7)2.0 µm). Our re-measurements of the type specimen agree with these. Our specimen differs from C. pauper in only having one category of evenly spined echinating acanthostyles, larger oxhorn toxas, and much longer principal styles.

Distribution. Currently only known from the type and holotype localities.