Clytia hummelincki

Remarks. This species is easily recognizable due to its generally shallow, wide hydrotheca, with even rim, and subhydrothecal spherule (Cornelius 1982). I have little to add to the previous descriptions of its trophosome (Leloup 1935, Millard 1975, Cornelius 1982, Calder 1991 d, Migotto 1996). The size of hydrothecae is highly variable among specimens from one colony (see table 2). The tentacle number in the present specimens varies between 24 and 30. There are 6 – 14 basal annuli and 4 – 7 additional ones in the middle part of the hydrothecal pedicels. The diaphragm of hydrotheca is obviously inclined to one side. Fertile material of C. hummelincki has rarely been described (Millard 1966, 1975). In the present specimens, the gonotheca is borne on a short, twisted pedicel (1 – 2 twists) arising from the hydrorhiza; it is inverted-conical in shape, widening gradually from base towards aperture. In lateral view, it appears asymmetrical, with one side straight to slightly curved, and the opposite one with significant basal curvature; both walls are smooth throughout. The distal end of the gonotheca is truncated; the aperture is wide and circular, closed by a thin, convex layer of perisarc. One or two medusa buds are present in the four gonothecae examined, but no morphological details could be observed. Additional studies are necessary in order to describe the complete life cycle of this species.

Distribution. Reported infrequently from warm waters of the western and eastern Atlantic, and eastern Pacific (Calder et al. 2003). TABLE 3. Comparative measurements of Clytia hummelincki (Leloup, 1935) from various sources, in µm. (1) Cited by Cornelius (1982).

Material examined. Stn. 3: 01.04.2008 — several colonies, 1.0 – 1.5 mm high, some with gonothecae, on algae and concretions. Stn. 7: 25.03.2008 — a sterile colony, ca. 2.5 mm high, on concretions; 27.03.2008 — three stems, ca. 1.0 mm high, no gonothecae, on Halimeda sp. Type locality. Bonaire Island, the Netherlands Antilles.