Halopteris alternata ( Nutting, 1900 )

Calder, Dale R., 2013, Some shallow-water hydroids (Cnidaria: Hydrozoa) from the central east coast of Florida, USA, Zootaxa 3648 (1), pp. 1-72 : 41-42

Halopteris alternata ( Nutting, 1900)

Fig. 11d, e

Plumularia alternata Nutting, 1900: 62 , pl. 4, figs. 1, 2.

Plumularia diaphana .— Weiss, 1948: 158 [not Plumularia diaphana ( Heller, 1868) ]. Type locality. Bahamas: Barracuda Rocks ( Nutting 1900: 62).

Voucher material. West Palm Beach , on reef seaward of the Breakers Hotel, 45 feet (13.7 m), together with Halopteris carinata , January 1991, SCUBA, one colony, 2.5 cm high, without gonophores, coll. P. Humann, ROMIZ B3974 .

Remarks. Halopteris alternata ( Nutting, 1900) was originally described from material collected by Alexander Agassiz and party during the cruise of the steamer Wild Duck to the Bahamas in 1893. Most authors during the twentieth century followed Bedot (1914) in regarding it as coterminous with H. diaphana ( Heller, 1868) , a species originally described from the Adriatic Sea. However, several characters distinguishing H. alternata from H. diaphana were documented by Schuchert (1997): (1) an axillar nematotheca is usually present distal to cauline hydrothecae; (2) segmentation of the hydrocaulus is homomerous rather than heteromerous; (3) hydrocladial internodes usually have one rather than 2–3 nematothecae; (4) female gonothecae are fusiform and straight rather than being cornucopia-shaped. Based on such differences, Halopteris alternata is now taken to be a valid species, and material examined above is assigned to it.

Reported distribution. Atlantic coast of Florida. Biscayne Bay ( Weiss 1948, as Plumularia diaphana ).

Western Atlantic. South Carolina ( Wenner et al. 1984, as Halopteris diaphana ) to Brazil (Oliveira et al. submitted), including Bermuda ( Calder 1997, as H. diaphana ), the Gulf of Mexico ( Calder & Cairns 2009), and the Caribbean Sea ( Galea 2008). It is carried northwards to North Carolina (and probably beyond) on Sargassum and Turbinaria ( Fraser 1912b, as Plumularia alternata ).

Elsewhere. Eastern Atlantic ( Ansín Agís et al. 2001). Records from the Pacific and Indian oceans are questionable (see Ansín Agís et al. 2001; Galea 2008).

Figures

FIGURE 11. a, Antennella gracilis: part of hydrocaulus with two hydrothecae, ROMIZ B1090, scale equals 0.25 mm. b, Antennella incerta: front view of hydrotheca, showing laterally-displaced axillar nematotheca, ROMIZ B3973, scale equals 0.25 mm. c, Antennella incerta: hydrocaulus with three hydrothecae, ROMIZ B3973, scale equals 0.25 mm. d, Halopteris alternata: part of hydrocaulus with a hydrocladium and two hydrothecae, ROMIZ B3974, scale equals 0.20 mm. e, Halopteris alternata: part of hydrocladium with two hydrothecae, ROMIZ B3974, scale equals 0.20 mm. f, Halopteris carinata: part of hydrocladium with two hydrothecae, ROMIZ B1128, scale equals 0.20 mm. g, Halopteris carinata: male gonotheca, ROMIZ B1128, scale equals 0.25 mm. h, Halopteris carinata: female gonotheca with two nematothecae, ROMIZ B1128, scale equals 0.25 mm.