Crypthelia micropoma Cairns, 1985

Cairns, Stephen D. & Zibrowius, Helmut, 2013, Stylasteridae (Cnidaria, Hydrozoa, Filifera) from South Africa, Zootaxa 3691 (1), pp. 1-57 : 45-48

Crypthelia micropoma Cairns, 1985

Figs. 21 A–K, 31

Crypthelia micropoma Cairns, 1985: 736 –739, figs. 23–31.

Types and Type Locality. Holotype deposited at the NMNH (USNM 72354), and paratypes at the NMNH and BM. Type Locality: 2°42’S, 40°53’E (off Malindi, Kenya), 140 m.

Material Examined. MN ZF2, SAM, and SEM stub 1687–1689 (USNM); MN SM162, 2 branch fragments SAM, and SEM stub 1684 (USNM); MN SM185, 4 branch fragments, male and female, SAM; UCTES SCD301, 1 female and 1 male colonies, Naturalis Biodiversity Centre. Types.

Description. Colonies are uniplanar and small, the holotype only 22.7 mm in height, and 17 mm in width, with a 2.8 mm basal branch diameter. Branching is dichotomous, the distal branches usually of lesser diameter than the cyclosystems they support. There is no evidence of polychaete commensalism. The coenosteal texture is a welldefined linear-imbricate ( Fig. 21 F), the strips being 65–70 µm in width and bordered by rather large coenosteal pores 20–25 µm in diameter; there are about 70 platelets per mm. The platelets are somewhat convex and slightly roughened by low longitudinal ridges. There are no nematopores.

Cyclosystems are unifacially arranged on all branches in a linear manner, circular to irregular in shape, and up to 1.3 mm in greater diameter ( Figs. 21 A, B). Based on 30 cyclosystems, the range of dactylopores per cyclosystem is 15–21; the average is 18.80 (ơ = 1.32); and the mode is 19. There are no diastemas.

The gastropore tube is double chambered ( Figs. 21 C, G), the lower chamber flattened, about 0.5 mm in diameter and 0.11 mm in height. The base of the lower chamber sometimes bears numerous slender spines (needles), each up to 59 µm in height and about 8 µm in diameter ( Fig. 21 G, H), not to be confused with a true gastrostyle. The delicate gastropore ring constriction ( Figs. 21 C, G) is about 0.41 mm in diameter, and the roughly spherical upper chamber is about 0.80 mm in diameter. Dactylotomes are relatively short, and are 0.08–0.10 mm in width. Pseudosepta are of variable width, and sometimes narrower than the dactylotomes, ranging from 0.08–0.10 mm. The tops of the pseudosepta are highly porous and concave ( Figs. 21 D, E). Female cyclosystems with welldeveloped ampullae have a short and narrow lid, whereas male cyclosystems do not have lids at all.

Female ampullae are large (up to 1.9 mm in diameter), globular superficial masses invariable placed adjacent to a cyclosystem ( Figs. 21 A, B, I, J). Efferent pores were not observed in the limited material at hand, but open within the gastropore tube beneath the lid in the type material. Male ampullae are clustered as 4–6 irregular swellings around part of the perimeter of the cyclosystems; each has a small apical efferent pore ( Fig. 21 K).

Remarks. Already known as the shallowest of the Crypthelia species at 140 m, the South African records are found shallower still, at 85 m.

The male of this species is the only one in the genus to lack cyclosystem lids, and as such may be confused with the genus Conopora .

Distribution. Off South Africa, from Port Elizabeth to northern Natal, 85–630 m (Fig. 31); off Kenya, 140 m.

Figures

FIGURE 21. Crypthelia micropoma (A – B, D, I – J, female from MN ZF 2, SAM; C, E – H, K, male from MN ZF 2, SAM): A, stereo view of unifacial cyclosystems, some with female ampullae. B, stereo view of one intact and one spent female ampullae. C, stereo view of double-chambered gastropore tube. D – E, porous pseudosepta. F, stereo view of linear-imbricate coenosteal texture. G, longitudinal section of lower gastropore chamber. H, small spines in lower gastropore chamber. I – J, female ampullae adjacent to cyclosystems. K, stereo pair of male ampullae adjacent to a cyclosystem.