Calder, Dale R., 2019, On a collection of hydroids (Cnidaria, Hydrozoa) from the southwest coast of Florida, USA, Zootaxa 4689 (1), pp. 1-141: 56-57

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Clytia  sp.

Figs. 14View FIGURE 14 j–l, 16

Material examined. Caloosahatchee River at Fort Myers, 26°38.790’N, 81°52.354’W, on floating dock, less than 1 m, 18 July 2012, 7‰, several colonies, up to 2.1 cm high, with gonophores, coll. D. Calder, ROMIZ B4376.

Remarks. Colonies of this species were found in abundance at a low-salinity site (7‰) in the estuary of the Caloosahatchee River at Fort Myers, Florida. For a species of the genus Clytia Lamouroux, 1812  , the hydroids were notably robust, mostly erect and branched, and large in size (to 2 cm or more). Although colonies with mostly smooth gonothecae were collected, they could not be assigned with confidence to Clytia elsaeoswaldae Stechow, 1914  , or C. gracilis (M. Sars, 1850)  , or any other species of the genus Clytia  discussed above.

Two types of nematocysts were observed in this hydroid ( Fig. 16View FIGURE 16). They appear to correspond with A-type b-mastigophores (6.1–6.8 long x 1.6–2.0 μm wide, undischarged, n=10, ROMIZ B4376) and B-type b-mastigo- phores (9.0–10.3 long x 3.0–3.6 μm wide, undischarged, n=10, ROMIZ B4376). Those of the latter type ( Fig. 16bView FIGURE 16) differ in size and shape from those of hydroids identified here as C. elsaeoswaldae  ( Figs. 11c, dView FIGURE 11), providing additional evidence that the two are specifically distinct.

Certain species of Clytia  are known to inhabit brackish waters, but their identities remain obscure. One ecological equivalent is a hydroid identified by me ( Calder 1971) as Clytia hemisphaerica ( Linnaeus, 1767)  , found to be abundant in oligohaline waters (0.5–5‰) of both the Pamunkey River and the upper James River, Virginia, USA. I now regard that identification as questionable, even though C. hemisphaerica  appears to be a euryhaline species ( Cornelius 1995b: 254). Wedler (1973) identified hydroids from salinities above 20‰ in the brackish Ciénaga Grande of Santa Marta, Colombia, as Laomedea tottoni Leloup, 1935  . That species, taken to be identical with C. linearis ( Thornely, 1900)  , is different from material examined here.

I consider this species unidentifiable from presently known characters, and include it here simply as Clytia  sp.