Conopora sola, Cairns, Stephen D. & Zibrowius, Helmut, 2013

Cairns, Stephen D. & Zibrowius, Helmut, 2013, Stylasteridae (Cnidaria, Hydrozoa, Filifera) from South Africa, Zootaxa 3691 (1), pp. 1-57 : 40-42

Conopora sola sp. nov.

Figs. 3 C, 19A–J, 24

Etymology. From the Latin solus (meaning alone or solitary), a reference to the absence of a commensal polynoid polychaete.

Types and Type Locality. Holotype: female colony, MN SM237, SAM, and SEM stubs 1685–86 (USNM). Paratypes: MN SM86, 1 female, SAM; MN SM232, 3 female colonies (1 in alcohol), SAM; MN SM237, 1 female colony in alcohol, SAM; PF 14356–62, 1 female colony, SAM H1465; UCTES AFR950, 1 female colony, SAM; Valdivia 104, 2 female colony, ZMB 7039. Type Locality: 32°15.4’S, 29°09.7’E (continental slope off northern Eastern Cape Province, South Africa), 600– 650 m.

Material Examined. Types.

Description. Colonies are uniplanar and relatively small, the holotype ( Fig. 3 C) measuring 4.0 x 2.8 cm, with a broken basal branch 4.4 mm in diameter. Branching axils vary between 60–90°; branch anastomosis does occur. Distal branches are round in cross section, but the thicker, more proximal branches are rectangular in cross section, the longer axis of the rectangle being perpendicular to the plane of the colony; there are no polynoid tubes. The coenosteal texture is a well defined linear-imbricate ( Figs. 19 G–I), the strips being 50–60 µm in width, with approximately 55–70 platelet leading edges per mm. Each platelet bears 4–7 low longitudinal ridges, which terminate in a sinuous distal edge. The coenosteum, ampullae, cyclosystem sides, and pseudosepta are densely covered with low nematopore mounds, each mound about 40 µm in diameter, the apical pore being 8–9 µm in diameter, and the height only about 15 µm ( Fig. 19 J). The coenosteum is white.

Cyclosytems are sympodially arranged on the branch edges, 1.0– 1.2 mm in diameter, and circular to slightly irregular in shape. Based on 40 cyclosystems, the range of dactylopores per cyclosystem is 9–13; the average is 10.90 (ơ = 1.13); and the mode is 11. There are no diastemas, even in basal branches.

The gastropore is double chambered ( Fig. 19 B), but consists of three sections. The lower chamber is hemispherical, about 0.50 mm in diameter. The upper chamber is about the same size and shape, the two chambers separated by a thin gastropore ring constriction of about 0.4 mm diameter. Above the upper chamber is a roughly cylindrical tube that is flanked by the dactylotomes. The dactylotomes range from 0.10–0.15 mm in width, the pseudosepta ( Fig. 19 D) being slightly wider and more variable in width, ranging from 0.09–0.25 mm wide. The tops of the pseudosepta are flat to slightly convex.

Female ampullae are massive (up to 1.9 mm in diameter) swellings (not hemispherical) that occur adjacent to cyclosystems ( Figs. 19 A, B, E, F). They must be close to a cyclosystem as their efferent pores open into an adjacent upper gastropore tube, usually in a dactylotome region ( Figs. 19 A, B). Male ampullae are unknown.

Comparisons. Among the ten other Recent Conopora species, C. sola is clearly most similar to C. verrucosa , and indeed, may in the future prove to be merely a subspecies or population of that species. It is similar to C. verrucosa in its colony shape, nematopore distribution, coenosteal texture, and female ampullar structure (i.e., efferent pores leading to gastropore chamber), but does differ consistently in several characters. Conopora sola does not have a symbiosis with polychaete worms (but then the type of C. pauciseptata Broch, 1951 , a purported junior synonym of C. verrucosa from Discovery Seamount southwest of South Africa, also does not host a polynoid commensal). It does not have diastemate cyclosystems, even in the base of the colony, which gives it a higher range and average number of dactylopores per cyclosystem (average of 10.9 and mode of 11 compared to an average of 6.59 and mode of 8 for the type of C. pauciseptata according to Broch, 1951b). Finally, its female ampullae are larger than those of C. verrucosa .

Distribution. Off southeastern South Africa from southern Agulhas Bank to off Cape Saint Lucia, Natal (Fig. 24), 155– 620 m.

Figures

FIGURE 3. Colonies of various species: A, Stenohelia venusta, holotype. B, Stenohelia spinifera, holotype. C, Conopora sola, holotype. D, Conopora verrucosa, Valdivia 104. E – F, Conopora tenuiramus, E, female paratype from PF 14306; F, holotype. G – I, Crypthelia micropoma, UCTES SCD 301 (H, male; I, female).

FIGURE 19. Conopora sola, female holotype from MN SM 237, SAM: A, stereo view of cyclosystem, with female efferent pore visible in gastropore tube of lower polyp. B, longitudinal fracture of gastropore tube, with two female efferent pores visible in dactylotome region. C, a cyclosystem. D, pseudosepta. E – F, large female ampulla adjacent to a cyclosystem, covered with nematopore mounds. G – I, linear-imbricate coenosteal texture. J, nematopore mounds.