Inferiolabiata spinosa Cairns 1991

Inferiolabiata spinosa Cairns, 1991

Figs. 1 E, 7A–H, 25

Inferiolabiata spinosa Cairns, 1991: 41, 42–43, pls. 24c–f, 25a–e.—Cairns et al., 2009: 97 (listed).

Types and Type Locality. The holotype and most paratypes are deposited at NIWA (=NZOI), and some paratypes are at the NMNH (see Cairns 1991). Type Locality: 32°25’S, 167°35’E (southern Norfolk Ridge, New Zealand), 318– 383 m.

Material Examined. MN SM163, 10 dead fragments (2 female, 8 indet.), SAM, and SEM stub 1716 (USNM); PF 13654, 1 fragment, SAM H2818, and SEM stub 1675 (USNM); Anton Bruun 420A, 2 female, 2 male, and 1 indeterminate colonies, and several smaller branches, USNM 1172363; type series.

Description. The South African colonies are small (largest only 2 cm in height) but are robust in form, the terminal branches being blunt, round in cross section, and 2–3 mm in diameter; there are no commensal polychaete tubes. Specimens reported from off Kenya (e.g., the illustrated specimen, Fig. 1 E) are up to 7 cm in height. The coenosteal texture is imbricate (Fig. 7 C) but the lateral borders of the coenosteal strips are poorly defined and the leading edges of the platelets are finely crenelate; the corallum is white.

Gastropores are equally distributed on all branch faces, circular in shape, and 0.25–0.40 mm in diameter. The gastrostyle is elongate, the illustrated one (Fig. 7 D) 0.60 mm in height and 0.14 mm in diameter (L:D = 4.3), although no horizontal tabulae were noted. The style is covered with coarse cylindrical spines up to 50 µm in length. A well-developed, diffuse ring palisade, easily visible in apical view, occurs in the upper half of the gastropore tube, the globular elements up to 48 µm in diameter (Fig. 7 D). The abcauline dactylopore spines (Figs. 7 A, E, G) are up to 0.4 mm in height and 0.27–0.30 mm in width, having a dactylotome width of 0.13–0.15 mm. They are independent in placement (not laterally linked into crescents) and their outer surface is not ridged or spined, simply covered with fine, imbricate platelets. The multiple dactylostyles (3 per dactylopore spine, Figs. 7 F, G) are robust and easily seen in apical view, as they occur within the dactylopore spine well above the coenosteal surface. The dactylostyle elements are pillar-shaped and up to 50 µm in height.

Female ampullae are superficial hemispheres up to 0.8 mm in diameter, each having a lateral efferent pore about 0.16 mm in diameter (Fig. 7 H). Male ampullae are mammiform, about 0.50 in diameter, and have a large irregularly-shaped apical efferent pore up to 0.15 mm in diameter.

Comparisons. Inferiolabiata spinosa is most similar to I. lowei, in that both species have robust blunt branches, lack polychaete symbionts, and have independent dactylopore spines. I. spinosa differs in having a more pronounced and consistently imbricate coenosteal texture, much more robust ring palisade and dactylostyles (the latter of which continue to the distal end of the dactylopore spines), non-ridged dactylopore spines, and a less spacious gastropore tube. The South African specimens were also collected at a shallower depth than those from the New Zealand region. These two species are also compared by Cairns (1991: Table 4) in tabular form.

Remarks. Although only several small branches were available from South Africa, these specimens compare favorably to the New Zealand type series of I. spinosa, differing only in having slightly smaller gastropores and a larger male efferent pore. Larger specimens are reported herein from off Kenya.

Distribution. South Africa, continental shelf off Eastern Cape Province (Fig. 25), 90–93 m; off Kenya, 140 m; New Zealand region, southern Norfolk Ridge, southern Kermadec Ridge, off North Cape; off Auckland Island, 211– 781 m.