Homaxinella erecta ( Brøndsted, 1924 )

Peart, Rachael A., Spong, Keren, Sutherland, Judy & Kelly, Michelle, 2019, A new species of sponge-dwelling amphipod, Polycheria spongoteras sp. nov., from Spirits Bay, Northland, New Zealand, Zootaxa 4674 (1), pp. 127-141 : 138-139

Homaxinella erecta ( Brøndsted, 1924)

( Figs 1B , 6 ; Table 2 )

Hymeniacidon erecta Brøndsted, 1924: 479 , fig. 32a–b.

Axiamon erecta .—de Laubenfels 1936: 130.

Homaxinella erecta .— Bergquist 1970: 13–14, pl. 1a–b, 14a; Pritchard et al. 1984: 66–67; Kelly et al. 2009: 44; Battershill et al. 2010: 110; Kelly & Herr, 2018: 49.

Not Axiamon erecta .— Bergquist 1961: 41, fig. 12.

Material examined. NIWA 93004 , NIWA Stn KAH1706/10-A1, Spirits (Piwhane) Bay, Northland, New Zealand, 34.384°S, 172.802°W, 42 m, grab sample, 31 May 2017 .

Type locality. Little Barrier Island , Hauraki Gulf, 55 m.

Distribution. Spirits Bay, Aupouri Peninsula, Northland, 44 m; North Cape, 42–85 m; Waiheke Island, 11–18 m; Cape Rodney-Okakari Pt Marine Reserve (Goat Island Sponge Garden, 30–40 m); Takatu Pt, Tawharanui Peninsula, Hauraki Gulf, 11 m; Waitemata Harbour, Hauraki Gulf, 10 m; East Cape, 37 m; Manukau Harbour, 11 m.

Description. Holotype cylindrical, c. 45 mm long, 3–4 mm thick, attached to shell of bivalve ( Brøndsted 1924). Surface optically smooth, microscopically hispid, texture of stalk and base tough, extremities softer, compressible, easily torn; flexible overall. Other material ramose with simple, erect cylindrical form, or with thin, whip-like multiple branches in planar or bushy arrangement, up to 20 cm high, diameter of branches up to 4 mm, stalk diameter 1.5–2.5 mm. Colour in life dull to deep yellowish orange, cream in preserved condition. Skeleton a very dense feltwork of spicules, partly confused, partly forming longitudinal fibres that anastomose to form loose axis from which diverge towards surface ectosome (modified from Bergquist 1970).

NIWA 93004 club-shaped with rounded apex and slim peduncle attached to unidentified shell substrate ( Fig. 1B ); sponge body 53 mm long, 8 mm maximum diameter.

Spicules. Styles to subtylostyles ( Table 2 , Fig. 6 ). straight to curved, with irregular expansion below head of spicule, distal ends often hollow, 200–700 µm long × <8 µm thick.

Substrate, depth range and ecology. Homaxinella erecta is a relatively uncommon species that is nearly always attached to shell substrate, commonly Tawera spissa ( Deshayes, 1835) , the horse mussel, Atrina zelandica ( Gray, 1835) (see Bergquist 1970; Pritchard et al. 1984) or the valves of dead scallops, Pecten novaezealandiae Reeve, 1852 ; 6– 85 m. Pritchard et al. (1984) noted that H. erecta was found on deep reef flats covered in a thin layer of fine sand. Specimen NIWA 93004 is the only example of Homaxinella erecta in the NIWA collection that was host to the amphipod, Polycheria spongoteras sp. nov.

Remarks. Brøndsted distinguished Homaxinella erecta from Hymeniacidon haurakii Brøndsted, 1924 , on the basis of morphology, the former being an erect pedunculate sponge, and the latter forming a solid, fibrous mass that incorporates shell material. The megascleres of NIWA 93004 are shorter and finer than for other records ( Table 2 ), which may be explained in part by the irregular formation of the style in the subtylostyles, and the occurrence of hollow distal tips and that were found to be quite common, indicating a lack of biologically available silica in the seawater in the region. Battershill et al. (2010: 110) illustrated what they believed to be Homaxinella erecta , but the image is not correctly identified, and is probably Grantia ramulosa Dendy, 1924 .

Figures

FIGURE 1. A. Type locality of Polycheria spongoteras sp. nov. Spirits Bay, Northland, New Zealand. B. Homaxinella erecta (Brondsted, 1924), 53 mm total length, with amphipod Polycheria spongoteras sp. nov. in residence (upper middle) in pocket 1.5 mm long (framed in box).

FIGURE 6. Homaxinella erecta (Brøndsted, 1924), NIWA 93004: a range of curved and straight styles and subtylostyles, scale bar = 100 µm.