Dynamena disticha ( Bosc, 1802 )

Calder, Dale R., 2013, Some shallow-water hydroids (Cnidaria: Hydrozoa) from the central east coast of Florida, USA, Zootaxa 3648 (1), pp. 1-72 : 27

Dynamena disticha ( Bosc, 1802)

Fig. 8d

Sertularia disticha Bosc, 1802: 101 , pl. 29, fig. 2.

Type locality. Atlantic Ocean: “...sur le fucus natans ...” ( Sargassum natans ) ( Bosc 1802).

Voucher material. Fort Pierce , Fort Pierce Inlet State Park, 27°28’29.5”N, 80°17’25.8”W, on stranded Sargassum sp. , 14.vii.2012, 28° C, 35‰, collected manually, one colony, 4 mm high, without gonophores, coll. D.R. Calder, ROMIZ B3966 .

Remarks. Hydroids referred to Dynamena disticha ( Bosc, 1802) in the western Atlantic occur in two forms, a stunted one (<1 cm high) found on floating Sargassum and a much larger one (up to 5 cm high) on a variety of benthic substrates. It remains to be confirmed whether they are actually conspecific. Specimens observed here, growing on a species of Sargassum , were of the stunted variety as originally described by Bosc (1802).

Comments on the taxonomy of this species have been given earlier ( Calder 1991a). Included in the synonymy of D. disticha therein were the following, all originally described from the western North Atlantic: Sertularia exigua Allman, 1877 , S. distans Allman, 1877 , S. complexa Clarke, 1879 , Dynamena bilatteralis Brooks, 1883 , Sertularia mayeri Nutting, 1904 , S. pourtalesi Nutting, 1904 , and with question Dynamena cornicina McCrady, 1859 . An extensive list of literature on D. disticha was given in Medel & Vervoort (1998).

Reported distribution. Atlantic coast of Florida. First record.

Western Atlantic. Massachusetts ( Nutting 1901, as Sertularia cornicina and S. complexa ) to Argentina (Oliveira et al. submitted), including Bermuda ( Calder 1991a), the Gulf of Mexico ( Calder & Cairns 2009), and the Caribbean Sea ( Calder & Kirkendale 2005; Galea 2008). The species has been reported on Sargassum in the Gulf Stream as far north as Nova Scotia ( Fraser 1918, as S. cornicina ).

Elsewhere. Circumglobal in tropical, subtropical and temperate waters ( Peña Cantero & García Carrascosa 2002).

Figures

FIGURE 8. a, Diphasia digitalis: part of a hydrocladium with hydrothecal pairs, ROMIZ B3964, scale equals 0.25 mm. b, Dynamena crisioides: part of hydrocaulus with basal part of a hydrocladium and hydrothecae, ROMIZ B3965, scale equals 0.25 mm. c, Dynamena dalmasi: part of hydrocaulus with two hydrothecal pairs, ROMIZ B1081, scale equals 0.25 mm. d, Dynamena disticha: part of hydrocaulus with two hydrothecal pairs, ROMIZ B3966, scale equals 0.20 mm. e, Pasya quadridentata: part of hydrocaulus with three hydrothecal pairs, ROMIZ B1085, scale equals 0.25 mm. f, Pasya quadridentata: gonotheca, ROMIZ B1085, scale equals 0.25 mm. g, Salacia desmoides: part of hydrocaulus with two hydrothecal pairs, ROMIZ B3967, scale equals 0.25 mm. h, Sertularella areyi: part of hydrocaulus with two hydrothecae, ROMIZ B1135, scale equals 0.5 mm. i, Sertularella conica: part of hydrocaulus with three hydrothecae, ROMIZ B1087, scale equals 0.25 mm.