Lepidopora granulosa

Lepidopora granulosa (Cairns, 1983a)

(Fig. 16)

Sporadopora granulosa Cairns, 1983a: 67–72, figs. 1c, 4a–g, 5a–c, map 2

Distribution. Malvinas Plateau; Scotia Ridge from Tierra del Fuego to Shag Rocks, 357–1874 m. New record off Mar del Plata, 1200 m.

Material examined. USNM 52697 (holotype) off south of Tierra del Fuego, Eltanin St. 740 (56° 06–07’ S, 66°19–30’ W); USNM 52698 (paratype) off south of Tierra del Fuego, Eltanin St. 740; MACN-In 42509 off Mar del Plata, Argentina, St. 15 (38° 0.500’ S, 54° 25.069’ W), 1200 m, August 2012.

Description. Colony uniplanar to slightly bushy, since some branches curve forward or sideways (Fig. 16a). It is broken at base, with thick smooth branches that thin gradually from base to bluntly-rounded tips. It is 7.0 cm wide and 5.5 cm tall. Branches round to oval in cross section (basal branches tend to be more oval), with larger axis parallel to plane of fan. No anastomosis. Basal branch 0.7 x 0.5 cm wide and thinnest branch 0.3 cm wide at its base. Polychaete tube absent. Anemone attached to one of the branches.

Coenosteum white and compact, with a more or less reticulate pattern of coenosteal canals, and covered in round, protuberant granules small and large (15 to 39 µm wide) (Fig. 16c). Some of the large granules are clustered together forming curved ridges. Granules may also have a more conical shape, in probably more eroded parts of the branch. Coenosteal canals are perforated by short slits 8–20 µm wide.

Gastropores and dactylopores spread randomly on branches (Fig. 16c), more frequent in anterior face and sparser towards base. Tubes axial, the longest clustered at branch axis (Fig. 16d). Gastropores round and flush, 0.24–0.48 mm wide (average 0.37 mm, n=59, σ=0.05). Gastrostyle needle-shaped and covered from base to tip with long spines that may bear one or more bifurcations (Fig. 16b). Ring palisade not identified. Gastrostyle not as long as gastropore tube (it is not seen from branch surface). Dactylopores round and rimmed, 0.07–0.14 mm wide at their opening (n=12). Dactylostyles absent.

Ampullae internal and ovoid in shape, with greater axis parallel to branch surface, or slight protuberances with an apical zone. No efferent pores identified. Sex unknown.

Discussion. Lepidopora granulosa was originally described by Cairns (1983a) as Sporadopora granulosa based on specimens from Malvinas and Scotia Ridge. Cairns (1983b) then transferred this species to the genus Lepidopora. The present record is the second for L. granulosa and extends its distribution further north.