Tridentata loculosa ( Busk, 1852 )

Calder, Dale R., 2013, Some shallow-water hydroids (Cnidaria: Hydrozoa) from the central east coast of Florida, USA, Zootaxa 3648 (1), pp. 1-72 : 31

Tridentata loculosa ( Busk, 1852)

Fig. 9d

Sertularia loculosa Busk, 1852: 393 .

Type locality. Australia: Bass Strait ( Busk 1852: 393) .

Voucher material. Off Fort Pierce Inlet , 27°28.8’N, 80°14.5’W, 15 m, 13.ii.1974, R/ V Gosnold Station 220/ 224, 10-foot otter trawl, four colony fragments, on bryozoans and algae, up to 1.3 cm high, without gonophores, ROMIZ B1078 .

Remarks. Contrary to information in synonymy lists of several papers reporting on this species, the original description of Sertularia loculosa by Busk (1852) was not accompanied by illustrations. Busk’s unfortunate omission of them led to much confusion over the identity and synonymy of the species. The first published figures of S. loculosa were by Bale (1884: pl. 4, figs. 5–6, pl. 9, fig. 12, pl. 19, fig. 9), drawn from sketches sent to him by Busk, but they too were misleading in that they showed pronounced marginal cusps bordering the rim of each hydrotheca. Those inaccurate drawings led Billard (1909) to mistakenly assume that S. loculosa was conspecific with S. turbinata ( Lamouroux, 1816) . A more representative drawing of S. loculosa , based on type material, was not published until later ( Bale 1913, pl. 12, fig. 6, under S. turbinata ). Problems surrounding the history and synonymy of the species were reviewed and clarified by Billard (1927), who concluded that S. loculosa was indeed valid and that S. ligulata Thornely, 1904 was identical to it. Migotto (1996) examined type material and confirmed the identity and validity of the species.

A strap-like “ligula” or nematophore, extending from the adcauline side of the hydranth and curving towards the hydrothecal orifice, is diagnostic of the species. It was poorly preserved in most hydranths of the colony examined here.

Sertularia loculosa has been assigned here provisionally to Tridentata Stechow, 1920 . Besides the presence of a characteristic ligula, marginal cusps are inconspicuous and the valves of the operculum differ greatly in size, as noted by Schuchert (2003). Molecular studies are needed to better establish its generic identity. It is clearly not congeneric with Sertularia argentea Linnaeus, 1758 , type species of Sertularia Linnaeus, 1758 .

Reported distribution. Atlantic coast of Florida. First record.

Western Atlantic. Florida (this study) to Brazil (Oliveira et al. submitted, as Sertularia loculosa ), including Bermuda ( Calder 2000) and the Caribbean Sea ( Calder & Kirkendale 2005; Galea 2008, as S. loculosa ).

Elsewhere. Warm eastern Atlantic; Indo-Pacific ( Schuchert 2003, S. loculosa ).

Figures

FIGURE 9. a, Sertularella unituba: part of hydrocaulus with two hydrothecae, ROMIZ B1099, scale equals 0.25 mm. b, Sertularella unituba: gonotheca, ROMIZ B1099, scale equals 0.25 mm. c, Tridentata distans: part of hydrocaulus with four hydrothecal pairs, ROMIZ B3968, scale equals 0.20 mm. d, Tridentata loculosa: part of hydrocaulus with two hydrothecal pairs, ROMIZ B1078, scale equals 0.20 mm. e, Tridentata marginata: part of hydrocaulus with two hydrothecal pairs, ROMIZ B3969, scale equals 0.35 mm.; f, Tridentata marginata: gonotheca, ROMIZ B3969, scale equals 0.25 mm. g, Tridentata turbinata: part of hydrocaulus with two hydrothecal pairs, ROMIZ B3970, scale equals 0.25 mm. h, Hincksella brevitheca: part of hydrocladium with hydrothecae, ROMIZ B1079, scale equals 0.25 mm. i, Synthecium tubithecum: part of hydrocladium with two hydrothecal pairs, ROMIZ B1074, scale equals 0.25 mm.