Amphinema, Haeckel, 1879

Calder, Dale R., 2019, On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA, Zootaxa 4689 (1), pp. 1-141: 23-24

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Amphinema  sp.

Fig. 2f, gView FIGURE 2, 4View FIGURE 4

Material examined. Naples ( FL), Doctors Pass, north jetty, channel side, on stolonal bryozoan on boulder,

26°10’29.14”N, 81°48’53.45”W, ELWS, 06 December 2017, one stolonal colony, 2 mm high, without gonophores, coll. D. Calder, ROMIZ B4337GoogleMaps  .— Captiva Island , Turner Beach, on jetty  , 26°28’57.3”N, 82°11’02.8”W, on rocks at low tide, 01 March 2018, several colony fragments, up to 4 mm high, without gonophores, coll. D. Calder, ROMIZ B4338GoogleMaps  .

Remarks. While these hydroids have been assigned to Amphinema Haeckel, 1879  (family Pandeidae Haeckel, 1879  ), no gonophores were present in the examined specimens. Their trophosomes resemble those of species such as A. dinema ( Péron & Lesueur, 1810)  and A. rugosum ( Mayer, 1900a)  , whose medusa stages have been reported from the southeastern Gulf of Mexico ( Mayer 1910a; Segura-Puertas et al. 2009), but these sterile specimens cannot be confirmed as conspecific with either one from current evidence. The cnidome comprised the usual categories of nematocysts found in pandeids and bougainvilliids, namely desmonemes (3.2 – 3.8 long x 1.7 – 2.2 μm wide, undischarged, n=10, ROMIZ B4338) and microbasic euryteles (6.2 – 7.1 long x 1.9 – 2.2 μm wide, undischarged, n=10, ROMIZ B4338). In size and shape, the euryteles approached those of A. dinema ( Péron & Lesueur, 1810)  as described by Russell (1938), and those of both A. dinema  and A. rugosum  as described by Schuchert (1996). Most notably, they were longer and much more slender than those of the bougainvilliid Bougainvillia rugosa  from the study area. Nevertheless, life cycle or molecular studies of conspecifics from the study area are needed to resolve the specific identity of this hydrozoan.