Hamigera bakusi n. sp.

urn:lsid:zoobank.org:act: C7F7FD4E-0E55-4E8A-B9A8-EA07E427D86A

Figure 6

Diagnosis. Compound oscula in sieve plates in crater-like depressions surrounded by shallow chimneys; colour always a shade of orange.

Etymology The name, suggested by the late Dr. W.C. Austin, is in honour of Dr. Gerald Bakus who conducted pioneering taxonomy on Poecillosclerida in the Puget Sound/San Juan Islands region in the mid-1960s and continued active research on sponge taxonomy for several decades thereafter.

Material Examined Holotype RBCM 024-00010 - 001, Stn NM 397, Defence Isl (E), Howe Sd., BC, 49° 34.511’ N / 123° 16.425’ W, coll. N. McDaniel, 30 Sept 2019, 15 m depth, 1 specimen. Paratype RBCM 024-00010 - 002, Stn NM 394, Defence Isl (E), Howe Sd., BC, 49° 34.511’ N / 123° 16.425’ W, coll. N. McDaniel, 24 Sept 2019, 15 m depth, 1 specimen.

Description

External (Figure 6A) Holotype RBCM 024-00010-001. Moderately thick encrusting with sieve plates in crater-like depressions; sponge 12 x 8 x 0.5 cm. Surface finely microhispid, densely micropapillate. Oscula compound on shallow chimneys and 3–4 mm diameter (Figure 6B). Oscula chimneys can be partly or completely closed voluntarily (Figure 6A). Ostia not visible in preserved specimen. Colour lemon yellow to orange. Consistency fairly easily torn.

Skeleton (Figure 6C) The ectosome is a 30–50 µm thick layer packed with tornotes perpendicular to the surface and isochelas; single subtylotes may penetrate the surface up to 100 µm. Choanosome plumose tracts branching and anastomosing. Large styles predominate deeper in the sponge while subtylotes mixed mostly with shorter styles predominate closer to the surface. Deeper in the sponge larger styles cross connect tracts randomly forming a very loose reticulation. Tracts are 100–150 µm thick just below the ectosome. Deeper in the choanosome tracts become more diffuse and vague or may become plumose. Subtylotes and isochelas are scattered throughout the choanosome.

Spicules (Figures 6D, E, F and G) Large and small styles, subtylotes, spatulate arcuate isochelas. Large styles (Figure 6D) gently curved or straight; sharp apices; heads slightly swollen, dimension range 378–536 x 18.2–26.0 µm. A few immature. Small styles (Figure 6E) same shape as large styles, shorter and thinner; apices may be mucronate, dimension range 190–263 x 13.0–18.2 µm. Tornotes (Figure 6F) inequiended, straight, swollen heads, shafts smooth or slightly polysubtylote, dimension range 252–368 x 7.3–10.4 µm. Spatulate arcuate isochelas (Figure 6G) strongly bent; spatulate alae, 33.8–49.4 µm. Immature isochelas fairly common. Table 6 compares spicule dimensions of specimens examined.

n = 50.

Distribution Widely distributed and abundant in BC; Howe Sound, Sechelt Inlet, Strait of Georgia. Shallow subtidal, 10–20 m depth.

Ecology Forms moderately thick encrustations up to 15 cm in diameter on bedrock.

Remarks Hamigera bibiloniae Santín, Grinyó, Uriz & Gili, 2020, H. dendyi Shaw, 1927, H. kellyae Santín, Grinyó, Uriz & Gili, 2020, H. macrostrongyla Bergquist & Fromont, 1988, H. strongylata Burton, 1934, and H. macrostrongyla Bergquist & Fromont, 1988 have strongyles and no tornotes. Hamigera cleistochela Bertolino, Costa & Pansini, 2019 has cleistochelas.

Hamigera hamigera is closest to H. bakusi n. sp. but oscula are not described as compound (Van Soest 2002 [2004]a) and H. hamigera can be lobate. Hamigera hamigera has only one size class of shorter, thinner styles (240–320 x 5–9 µm vs. 378–536 x 18.2–26.0 µm and 190–263 x 13.0–18.2 µm in H. bakusi n. sp.). Isochelas of H. hamigera are smaller (15–20 µm vs. 33.8–49.4 µm for H. bakusi n. sp.) (Van Soest 2002 [2004]a).