Halopteris diaphana ( Heller, 1868 )

Calder, Dale R., 2013, Some shallow-water hydroids (Cnidaria: Hydrozoa) from the central east coast of Florida, USA, Zootaxa 3648 (1), pp. 1-72 : 43-44

Halopteris diaphana ( Heller, 1868)

Fig. 13b–d

Anisocalyx diaphanus Heller, 1868: 42 , pl. 2, fig. 5.

Type locality. Croatia: Capocesto (Primošten) ( Heller 1868: 42) .

Voucher material. Off Melbourne, 28°04.0’N, 80°12.8’W, 25 m, 01.iii.1974, R/ V Gosnold Station 222/281B, Smith-McIntyre grab, several fragments of a colony, on a bivalve shell, up to 7 mm high, with gonophores, ROMIZ B3975 .

Remarks. Material examined here was small and exceedingly slender, and its identity at first seemed uncertain. Within the genus Halopteris Allman, 1877 , however, these specimens are clearly referable to the H. diaphana ( Heller, 1868) group as recognized by Schuchert (1997). Amongst species of that group, they most closely resemble H. diaphana , H. tenella ( Verrill, 1874) , H. alternata ( Nutting, 1900) , and H. violae Calder, Mallinson, Collins, & Hickman, 2003 . Specimens resemble those of H. diaphana , H. tenella , and H. violae in the usual sequential segmentation of hydrocladia, with the first segment being very short and anematothecate, the second longer and nematothecate, and the third long and both nematothecate and hydrothecate. Female gonothecae are cornucopia-shaped, as in H. diaphana and H. tenella , rather than fusiform or nearly so as in both H. alternata and H. violae . Unlike in H. alternata , axillar nematothecae are absent on hydrocauli. Cauline internodes generally bear two nematothecae, as in H. diaphana and H. tenella . Most importantly, hydrocauli are heteromeric (including some cormoid stems that are unbranched, as in Antennella Allman, 1877 ), unlike any species in the group except H. diaphana . Based on Schuchert’s (1997: 42) tabular comparison of species in the group, material at hand fully corresponds with characters of H. diaphana and is assigned to that species here. Halopteris diaphana has been justifiably reported before in the western Atlantic only from Brazil ( Schuchert, 1997).

A revision of the taxonomy of Halopteris diaphana as now conceived is given by Schuchert (1997). In the western Atlantic, hydroids referable to H. alternata ( Nutting, 1900) have often been misidentified as this species.

Reported distribution. Atlantic coast of Florida. First record.

Western Atlantic. Melbourne, Florida (reported herein) and Brazil ( Schuchert 1997).

Elsewhere. Mediterranean Sea ( Schuchert 1997).

Figures

FIGURE 13. a, Halopteris clarkei: part of hydrocaulus with two hydrocladia and three hydrothecae, ROMIZ B1096, scale equals 0.25 mm. b, Halopteris diaphana: part of hydrocaulus with a hydrocladium and a hydrotheca, ROMIZ B3975, scale equals 0.20 mm. c, Halopteris diaphana: part of a hydrocladium with a hydrotheca and nematothecae, ROMIZ B3975, scale equals 0.10 mm. d, Halopteris diaphana: part of hydrocaulus with a hydrotheca and female gonotheca, ROMIZ B3975, scale equals 0.10 mm. e, Monostaechas quadridens: part of a hydrocladium with two hydrothecae and a female gonotheca, ROMIZ B1102, scale equals 0.25 mm. f, Ventromma halecioides: part of hydrocaulus with a hydrocladium and two hydrothecae, ROMIZ B1108, scale equals 0.20 mm.