Polymastia piscesae, Austin, William C., Ott, Bruce S., Reiswig, Henry M., Romagosa, Paula & G, Neil, 2014

Austin, William C., Ott, Bruce S., Reiswig, Henry M., Romagosa, Paula & G, Neil, 2014, Taxonomic review of Hadromerida (Porifera, Demospongiae) from British Columbia, Canada, and adjacent waters, with the description of nine new species, Zootaxa 3823 (1), pp. 1-84 : 31-33

Polymastia piscesae n. sp.

Fig. 10 A–I

Etymology. The species was named after PISCES IV, the submersible used to collect this species and many others in BC deep waters.

Material examined. Holotype: RBCM 009-00054-001, KML sta. 186/83, Observatory Inlet, BC, (55° 16.9′N, 129° 48.4′W), 213 m depth, coll. W.C. Austin, 1 specimen.

Description. Macroscopic features. Fig. 10 A. Sponge cushion-shaped; sampled fragment about 6 cm in greatest diameter by 1.2 cm thick, smooth in some regions, microhispid in others (spicules protrude 0.3–0.5 mm). Fistulae 1–1.8 cm high by 2.5–4 mm wide at base. Fistulae densely distributed across sponge surface (2 per mm2), conical or flattened with pointed apices. Three fistulae in the sample contain an osculum; the others are thinner and pointed with no indication of an apical opening. A cross section 1 mm back of the apex revealed 10 equal-sized 100 µm diameter canals. Colour in alcohol grey; fistulae cream colour.

Microscopic features, Fig. 10 B. Ectosome of main body cortical, 0.8 to 1 mm thick, with palisade of small tylostyles, apices outward, piercing surface. Underlain by intermediate tylostyles, mostly tangential to surface. Small tylostyles abundant.

Fistulae canals lined by tangential layer of intermediate tylostyles. Intermediate-size tylostyles at surface, forming discontinuous superficial palisade and extending up to 100 µm beyond the surface. Principal multispicular tracts radiating from choanosome into base of fistulae, but not penetrating fistular surface.

Choanosome composed of radiating multi-spicule tracts up to 5 mm thick, composed of principle styles or occasional subtylotes. Intermediate and small tylostyles scattered throughout choanosome. Principal spicules extending into ectosome, may or may not penetrate outer surface.

Spicules. Principal styles to subtylostyles straight to slightly curved (I). Intermediate tylostyles to subtylostyles (II), slightly curved, rarely fusiform; small tylostyles.

Holotype RBCM 009-00054-001 Remarks. P. piscesae n. sp. is compared with other Polymastia species known from the N. Pacific in Table 3, Table 4 and Fig. 6 . Polymastia kurilensis has only two types of tylostyles with the smaller forming an ectosomal palisade in contrast to three types of tylostyles and the lack of spines in P. piscesae n. sp. Polymastia pachymastia has stouter fistulae than P. piscesae n. sp., a different spicule compliment, and occurs in intertidal to shallow depths. Polymastia pacifica has cylindrical fistulae which are much smaller than the cone-shaped fistulae in P. piscesae n. sp. Polymastia granulosa Brøndsted, 1924 has principal subtylostyles which are approximately 40% of the length of those in P. piscesae n. sp. Polymastia laganoides lacks a palisade of small tylostyles, and has fistulae which are low warty protuberances; its megascleres are exclusively tylostyles rather than styles to subtylostyles. Polymastia affinis Thiele, 1898 has very large (to 6 mm) echinating styles, and fistulae are small and papillose, which is again different from P. piscesae n. sp. Both Polymastia affinis Thiele, 1898 and Polymastia fluegeli Lehnert, Stone & Heimler, 2005 have shorter and fatter fistulae than those in P. piscesae n. sp.

Differences in size and form between two types of fistulae in P. piscesae suggest they have separate inhalant and exhalent functions. This is confirmed by the presence of 10 equal-sized canals with no larger central canal in the thinner pointed fistulae indicating that they are solely inhalant.

In terms of the abundance, shape (elongate pointed inflated or flattened cones) and size (0.8 cm diam, 1.7 cm) of the fistulae, our specimen externally bears a strong resemblance to the smaller (5 cm x 6 cm) specimen of “ Polymastia robusta toporoki ” figured in Koltun (1966; Fig. 7 ). Koltun (1966) included Polymastia euplectella Resvoj 1927 as a synonym of Polymastia robusta . However, Plotkin (2004) considered Polymastia euplectella to be a valid species and he reported several differences from Polymastia robusta as characterized by Boury-Esnault (1987). These characters include: fistula length— P. euplectella (2–5 cm), P. ro bu s t a (0.2–0.8 cm), P. piscesae n. sp. (1–1.7 cm); exhalent and inhalant fistula— P. euplectella (present), P. ro bu s t a (absent), P. piscesae n. sp. (present); number of spicule types— P. euplectella (3), P. robusta (2), P. piscesae n. sp. (3).

The fistulae of P. euplectella are considerably larger than in our species. Polymastia euplectella has also not been recorded from the Pacific. Polymastia robusta has only 2 spicule types, lacking an intermediate tylostyle size class. It also does not have separate exhalent and inhalant fistulae as in P. piscesae .

Conclusions. We conclude that our specimen represents a new species based on differences in form and differential function of the fistulae from all North Pacific species. Polymastia euplectella has larger fistulae and occurs only in the Atlantic.

Bathymetric range. 213 m depth.

Geographic distribution. Known from the type locality only, Observatory Inlet, BC.

Figures

FIGURE 6. Multifistulate Polymastia spp. in the NW Pacific. Numbers, form and size of fistulae. Scale bar, 3 cm on all but C where scale bar 5 cm. A, P. kurilensis Koltun; B, P. laganoides Burton; C, P. fluegeli Lehnert et al.; D, large P. toporoki Koltun; E, small P. toporoki; F, P. affinis Thiele, fistulae contracted; G, P. affinis, fistulae expanded. A, D – G from Koltun 1966; B from Lambe 1895, courtesy Royal Society of Canada; C from Stone et al. 2011.

FIGURE 7. Polymastia kurilensis Koltun, 1962. A, thick cross section, scale bar 10 mm; B, long and short spicules, scale bar 100 µm; C, head of subtylostyle, scale bar 10 µm; D, barbed end of thin onychaete-like spicule, scale bar 10 µm.

FIGURE 10. Polymastia piscesae n. sp. A, large living specimen, scale bar approx. 1 cm; B, cross section showing fibre tracts extending to ectosome, scale bar 3 mm; C, palisade of small tylostyles in ectosome, scale bar 300 Μm; D, style I, scale bar 500 Μm; E, head of style I, scale bar 50 µm; F, subtylostyle II, scale bar 100 µm; G, tylostyle II, scale bar 50 µm; H, fusiform tylostyle III, scale bar 200 Μm; I, head of tylostyle III, scale bar 10 µm.