Thyroscyphus marginatus ( Allman, 1877 )

Calder, Dale R., 2013, Some shallow-water hydroids (Cnidaria: Hydrozoa) from the central east coast of Florida, USA, Zootaxa 3648 (1), pp. 1-72 : 23-24

Thyroscyphus marginatus ( Allman, 1877)

Fig. 7c, d

Obelia marginata Allman, 1877: 9 , pl. 6, figs. 1, 2.

Thyroscyphus marginatus .— Cummings, 1994: 1208.— Jones, 2002: 218.

Type locality. USA: Florida, off Loggerhead Key ( Allman 1877) .

Voucher material. Bethel Shoal off Vero Beach, 27°42.6’N, 80°06.8’W, 24 m, 18.ii.1976, Johnson-Sea-Link, JSL 328, diver lockout, one colony fragment, 3 cm high, without gonothecae, coll. S. Nelson, ROMIZ B3963 .

Remarks. Thyroscyphus marginatus ( Allman, 1877) is a conspicuous species, forming large colonies that reach as much as nine inches (23 cm) high ( Allman 1877). It is easily distinguished from the sympatric T. ramosus Allman, 1877 in having an entire (non-cuspate) rather than a four-cusped hydrothecal margin, and a single operculum that is shed rather than a persistent one of four valves.

In some earlier papers ( Calder 1993, 1998, 2000; Calder & Kirkendale 2005; Calder & Cairns 2009) I assigned this species to Cnidoscyphus Splettstösser, 1929 , a genus originally established with three included species ( Laomedea torresii Busk, 1852 ; Obelia marginata Allman, 1877 ; and Thyroscyphus aequalis Warren, 1908 ). No type species was designated for it until Vervoort (1993: 104) chose L. torresii Busk, 1852 as the name-bearing type. Cnidoscyphus was founded on an invalid character (presence of large nematocysts in the mantle lining of the hydrotheca, now known in several thyroscyphid and sertulariid genera) and it is currently regarded as a junior synonym of Thyroscyphus Allman, 1877 ( Bouillon et al. 2006).

This hydroid species is widely reported in the tropical western Atlantic (see records in Fraser 1944, as Campanularia marginata ; Vervoort 1968, as Cnidoscyphus marginatus ; Calder & Kirkendale 2005, as C. marginatus ; Galea 2008; Castellanos Iglesias et al. 2011). It extends northwards into shelf waters of the southeastern United States ( Cain 1972, as C. marginatus ; Wenner et al. 1983, 1984; Cummings 1994) and Gulf of Mexico ( Calder & Cairns 2009, as C. marginatus ), but is infrequent in estuaries of the region ( Calder 1983).

Reported distribution. Atlantic coast of Florida. Boca Raton ( Cummings 1994).—Biscayne Bay ( Jones 2002).

Western Atlantic. North Carolina ( Cain 1972, as Cnidoscyphus marginatus ) to Brazil (Oliveira et al. submitted), including Bermuda ( Calder 1991a), the Gulf of Mexico ( Calder & Cairns 2009, as C. marginatus ), and the Caribbean Sea ( Galea 2008).

Elsewhere. Eastern Atlantic ( Vervoort 1959, as C. marginatus ; Medel & Vervoort 1998, as C. marginatus ).

Figures

FIGURE 7. a, Symmetroscyphus intermedius: part of erect colony, ROMIZ B1117, scale equals 0.5 mm. b, Symmetroscyphus intermedius: part of colony with two hydrothecae, ROMIZ B1117, scale equals 0.25 mm. c, Thyroscyphus marginatus: part of hydrocaulus with three hydrothecae, ROMIZ B3963, scale equals 0.5 mm. d, Thyroscyphus marginatus: pedicel and hydrotheca, ROMIZ B3963, scale equals 0.25 mm. e, Thyroscyphus ramosus: part of hydrocaulus with four hydrothecae, ROMIZ B1133, scale equals 0.5 mm. f, Thyroscyphus ramosus: pedicel and hydrotheca, ROMIZ B1133, scale equals 0.25 mm.