Inferiolabiata lowei Cairns 1983

Inferiolabiata lowei (Cairns, 1983)

Figs. 1 D, 6A–M, 24

Errina labiata: Boschma & Lowe, 1969: 15, pl. 5, map 2.

Errina (Inferiolabiata) lowei Cairns, 1983a: 113 –117, figs. 22F–G, 28A–G.

Inferiolabiata lowei: Cairns, 1983b: 428, 451 (listed); 1991: 41, 43, pl. 25f–g, 26a–f.—Cairns et al., 2009: 97 (listed).

Types and Type Locality. The type series is housed primarily at the NMNH, with vouchers also deposited at Naturalis Biodiversity Centre and BM (see Cairns 1983a). Type Locality: 54°29’S, 39°22’W (west of South Georgia), 659– 686 m.

Material Examined. PF 907, 1 female colony, ex SAM 1489; MN SM185, 1 small fragment, SAM, and SEM stubs 1670–71, 1714 (USNM); type series.

Description (based on the larger South African specimen from PF907). The colony (Fig. 1 D) is robust, uniplanar, and sparsely branched, not hosting a commensal polychaete. It measures 3.7 cm tall and 8.9 mm in basal branch diameter, having a somewhat flattened terminal branch 6 mm in greater width. The coenosteal texture is reticulate-imbricate, often covered with a dense smooth material on the upper parts of the corallum (Fig. 6 C); the corallum is white.

Gastropores are equally distributed on all branch surfaces, circular in shape, and 0.35–0.40 mm in diameter. The gastrostyle is elongate and quite slender, only 0.11–0.14 mm in diameter, the proximal portions sometimes stabilized by tabulae (Fig. 6 K, M). A rudimentary diffuse ring palisade occurs in the upper gastropore tube, composed of globular elements about 35 µm in height. Because of the slender nature of the gastrostyle and the rudimentary ring palisade, there is ample space surrounding the style within the gastropore tube. Although the ring palisade is visible from an apical view of the gastropore, the gastrostyle tip is slightly recessed below the coenosteal surface. The abcauline dactylopore spines (Figs. 6 F–H) are up to 0.6 mm tall and 0.35–0.40 mm wide, in all cases the dactylotome occupying the entire length of the dactylopore spine (i.e., not proximally tubular). The exterior surface of the dactylopore spines is longitudinally ridged and spinose (Fig. 6 E), and their distal edges are finely serrate; they are invariably independent, not grouped in abcauline crescents. Most dactylopore spines have multiple (1–3), rudimentary dactylostyles (Figs. 6 G–J), the elements ranging from 35–45 µm in height.

The superficial female ampullae are 1.1–1.2 mm in diameter, although efferent pores were not observed.

Comparisons. See Comparisons of I. africana and Cairns (1991: Table 4) for comparisons of all species in this genus.

Remarks. The single South African specimen compares favorably with the South American type series, but differs in having slightly shorter dactylopore spines (those of the type series may be up to 1 mm), having a rudimentary ring palisade (those of the type series have none), and in having consistently independent, horseshoeshaped dactylopore spines, whereas those from the type series sometimes have their spines arranged in crescents beneath the gastropores and are occasionally cylindrical proximally, not unlike the conditions found in I. africana. The South African specimen was also collected from slightly shallower than those from off South America and New Zealand.

Distribution. South Africa, continental shelf off Eastern Cape Province (Fig. 24), 90–155 m; Southwest Atlantic, off southern Argentina, Tierra del Fuego, Burdwood Bank, South Georgia, and Drake Passage, 250–960 m; New Zealand region, southern Norfolk Ridge, Three Kings Ridge, southwestern South Island, 164–751 m (Cairns 1991).