Favosipora bathyalis, Gordon & Taylor, 2010

Gordon, Dennis P. & Taylor, Paul D., 2010, New seamount- and ridge-associated cyclostome Bryozoa from New Zealand, Zootaxa 2533 (1), pp. 43-68 : 55

Favosipora bathyalis n. sp.

( Fig. 8 A–D )

Material examined. Holotype: NIWA 61250 , from cruise TAN0413, Stn 177, 37°18.72’ S, 177°03.93– 177°04.26’ E, Bay of Plenty, northwest of Mahina Knoll , 550 m depth, collected 16 November 2004 . Paratypes: NIWA 61251 , same locality as holotype . Other material: TAN0413 Stns 59, 109, 171.

Distribution. Continental slope, central Bay of Plenty, New Zealand, 136– 910 m.

Etymology. In reference to the relatively deep-water occurrence of this species of Favosipora .

Description. Colony encrusting, circular, up to 3.47 mm in diameter, frequently supported by basal struts and typically forming smaller subcolonies above the primary layer so that a fully formed colony can resemble a three-tiered wedding cake in profile; zooids arranged more or less quincuncially, with short series (2–3) of zooidal peristomes separated by kenozooids; subcolonies 0.56–1.29 mm in height.

Young colonies fully or partially adnate, depending on substratum irregularity, surrounded by a thin, planar or upturned marginal lamina. Colony centre mainly comprising thick-walled kenozooids with rounded outlines; kenozooidal apertures 0.15–0.17 mm in diameter, reduced or closed by smooth calcification; open kenozooids with pinhead mural spines on wall interiors. Autozooidal peristomes 0.08–0.11 mm in diameter, the apertures circular; some sealed by terminal diaphragms with radial surface fabric.

Marginal lamina in some colonies with several indentations, marking shafts that descend to the substratum as hollow narrow props or broad struts. Skeletal ultrastructure of lamina comprising imbricating platey crystallites; these relatively large between developing lateral walls of zooidal chambers, minute and narrowly lath-like to granular where walls develop.

Budding of subcolonies takes place from a kenozooid and its quincuncial neighbours in the macular centre of the primary colony. The subcolony spreads across a quarter to a third of the parent colony, raising itself above it as a shallow dish. The only gonozooid encountered in this species was in the middle tier of a three-tiered colony (holotype), near the edge; brood chamber is short (0.45 mm) and very wide (1.33 mm) with a raised rim and has a densely pseudoporous exterior-walled surface and relatively large round ooeciopore, 0.09 mm in diameter, atop a short ooeciostome.

Remarks. Favosipora bathyalis is the sixth species of the genus to be discovered in the New Zealand EEZ, the other species having only recently been recognised as belonging to the genus or newly described (Gordon & Taylor 2001). This species is also the deepest-known in the genus. The tiny, transverse brood chamber is unlike those of congeneric species, including the Australian type species of Favosipora , F. rugosa .

Figures

FIGURE 8. Favosipora bathyalis n. sp. (TAN0413 Stn 177). A, profile of a three-tiered colony with basal struts; B, tiered holotype colony, the middle tier with very narrow brood chamber at far left; C, infertile colony centre; note pinhead spinules within zooidal peristomes; D, brood chamber and ooeciostome of holotype colony in B.