Reference: Biol. Bull., 151 : 214-224. (August, 1976) PODOCORYNE SELENA, A NEW SPECIES OF HYDROID FROM THE GULF OF MEXICO, AND A COMPARISON WITH HYDRACTINIA ECHINATA CLAUDIA E. MILLS 1 Department of Biological Science, Florida State University, Tallahassee, Florida 32306 Based on the adult medusa, Edwards (1972) has recently described a second species of Podocoryne from the New England coast of North America, Podocoryne aincricana, which had previously been called P. cornea Sars. Podocoryne amcricana attains an adult size of 3.5 mm in height with 24 to 32 marginal tentacles. Podocoryne cornea, which is also found in New England, is smaller and has fewer tentacles. The polyps of P. cornea and P. aincricana are very similar and the developmental stages of the medusae may also be confusingly similar, so that mature medusae may be necessary for positive identification of these two species. In this paper a third species of Podocoryne from North America, found on the north Florida coast of the Gulf of Mexico, is described. Podocoryne selena n. sp. is probably the same hydrozoan that has been referred to as P. cornea in north Florida by McLean (1975), Menzel (1971), Wells (1969), Shier (1965), and Joyce (1961). In spite of repeated attempts, this author has never collected P. cornea in Florida. Podocoryne selena n. sp. may also be identical to P. cornea in Texas (Wright, 1973; Defenbaugh and Hopkins, 1973; and Deevey 1950, 1954) and Louisiana (Cary and Spaulding, 1909). The polyp of P. selena n. sp. is very similar to the polyp of P. cornea ; medusae must be examined for positive identification in other coastal areas in order to establish the geographic ranges of the species of Podocoryne in North America. The hydroids Podocoryne and Hydractinia live on hermit crab shells and other hard substrates on the Atlantic and Gulf coasts of the United States. In New England specimens of Podocoryne cornea and Hydractinia cchinata are found in the same areas (Crowell, 1945), as are P. selena n. sp. and H. ecliinata in north Florida. For the non-specialist, it is sometimes difficult to distinguish Podocoryne from Hydractinia, both of which belong to the family Hydractiniidae. Podocoryne selena n. sp. and H. cchinata are compared in this paper through the use of both phase contrast and scanning electron microscopy. MATERIALS AND METHODS Hydroid colonies of Podocoryne selena, n. sp. were collected on the shells of live hermit crabs in the following locations in Frankin County, Florida : Alligator Point ; Alligator Harbor ; Baymouth Bar near Alligator Point and at the opposite end of the bar near St. Teresa ; Wilson's Beach at St. Teresa ; Turkey Point ; and in St. Joseph Bay in Gulf County at several points between PresnelFs Fish Camp and 1 Present address : 7044 50th Ave. N. E., Seattle, Washington, 98115. 214
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