Microporella sp. 1 Hincks 1877

Microporella sp. 1

Fig. 12; Table 9

NEW ZEALAND • Single infertile fragment; SW of South Island, Puysegur Bank; [46.43° S, 166.08° E]; depth 187 m; Recent; NHM-UIO BLEED 151 (voucher specimen).

COLONY. Erect, bifoliate, branches narrow; fragment available ca 3 mm wide with up to six linear series of alternating zooids on each side; interzooidal communications through multiporous septula visible at colony growing edge.

AUTOZOOIDS. Distinct with interzooidal boundaries marked by thin band of slightly raised calcification on either side of a narrow grooVe, rounded rectangular to hexagonal, longer than wide (mean L/W = 1.31). Frontal shield conVex, pustulose, the pustules flat-topped, Varying in size; marginal areolae numbering about 10–12, usually elongate (25–40 µm long) especially at zooidal corners, sometimes indistinguishable from frontal pores along lateral sides of the zooids; non-marginal pseudopores about 40–60, small (diameter 10–15 µm), irregularly scattered among pustules, sometimes coalescent.

ORIfICE. TransVersely D-shaped, significantly wider than long, hingeline with about 14–18 equal-sized teeth; oral spines lacking. Operculum smooth.

ASCOPORE fIELD. As a narrow band of gymnocystal calcification, at approximately same leVel as orifice but beneath leVel of adjacent frontal shield, located at ca 55–75 µm from the orifice hingeline, separated from it by non-porous pustulose cryptocyst; circular (diameter 50–60 µm) to transVersely elliptical (55 µm long by 80 µm wide), opening C-shaped, 10 × 50 µm, with tiny radial denticles, and a circular tongue projecting from the distal edge.

AVICULARIUM. Usually single, rarely paired, moderately large, present in all autozooids, positioned at level with the ascopore, oriented distolaterally, usually at about 45° to the long axis of the supportive autozooid; crossbar calcified; opesia semielliptical; rostrum short, subtriangular with concaVe sides, the distal end rounded, distinct channel present. Mandible 150–180 µm long, narrow and pointed. Multiple intramural buds observed in avicularia.

OVICELLS. Not observed.

Among all bifoliate congeners, Microporella sp. 1 mostly resembles M. hyadesi. The two species share a transVersely D-shaped orifice with equal-sized teeth in the hingeline, the characters of the ascopore and the appearance of the frontal shield made of flat-topped pustules. Differences include: the shape of the zooids (mean L/W = 1.67 and 1.31, respectiVely) which are rectangular and flat in M. hyadesi, rhomboidal to hexagonal and convex in Microporella sp. 1; the avicularium is more laterally oriented and has a wider channel in the rostrum than M. hyadesi. The two species also differ in their geographical distributions. The single available fragment of Microporella sp. 1 was found at Puysegur Bank, south west of South Island of New Zealand at a depth of 187 m, while M. hyadesi is a South Atlantic species found at a depth of 49–341 m (Hayward & Ryland 1990).