HYDROMEDUSAE OF THE GULF OF MEXICO 



By Mary Sears, Woods Hole Oceanographic Institution 



So few plankton collections have been made in 

 the Gulf of Mexico and so few of these have been 

 studied by hydromedusae specialists that it is 

 necessary to rely almost entirely on Mayer's 

 (1900, 1904, 1910) reports from the Tortugas. 

 It is to be noted that most names listed in Mayer's 

 first (1900) paper were reduced to the synonomy 

 of other species in his monograph of 1910. Sub- 

 sequent writers, expecially Bigelow (1913, 1918, 

 1919, 1938, 1940), Kramp (1919, 1920, 1926, 

 1930, 1932, 1933, 1939, 1942, 1947, 1948), and 

 Ranson (1936) have also made certain revisions 

 resulting in a slight reduction in the number of 

 species originally enumerated by Mayer in his 

 monograph (1910). 



In comparing the resulting list with that in 

 the section on the hydroids it is striking to note 

 that few species (i. e., Turritopsis nutricula 

 McCrady, Zanclea costata Gegenbaur, Bougain- 

 villia carolinensis McCrady, Pennaria tiarella 

 McCrady, and Cladonema mayeri Perkins among 

 the Anthomedusae) appear on both lists. In 

 large part this is due to the fact that many 

 hydroids do not liberate free-swimming medusae, 

 and that many medusae have very much reduced 

 hydroid stages. Indeed, in many instances the 

 hydroid stage is completely unknown, if it exists. 



Insofar as it has been possible to determine 

 only about 70 species have been recorded (30 

 Anthomedusae, 34 Leptomedusae, 5 Trachy- 

 medusae, and 3 Narcomedusae) from the Gulf 

 of Mexico region. Some of these, not already 

 mentioned above, are good species also known 

 elsewhere: 



Corymorpha nutans Hartlaub; Hybocodon forbesii Mayer; 

 Sarsia mirabilis L. Agassiz; Eclopleura minerva Mayer; 

 Dipurena ophiogaster Haeckel; Zancleopsis dichotoma 

 Mayer; Amphinema dinema P6ron et LeSueur; A. octaedra 

 Haeckel; A. rugosa Mayer; A. lurrida Mayer; Merga 

 violacea Agassiz and Mayer; Podocoryne minula Trinci; 

 Lymnorea alexandri Mayer; Bougainvillia niobe Mayer; 

 Kollikerina elegans Mayer; Proboscidactyla ornala Mc- 



Crady, among the Anthomedusae; Laodicea cruiciala 

 Forsk&l; Phalidium discoida Mayer; Phialucium carolinae 

 Mayer; Exicheilola ventricularis McCrady; E. duodecimalis 

 A. Agassiz; Eutima mira McCrady; E. elephas Haeckel; 

 Euiimalphes coerulea L. Agassiz; Phortis pyramidalis 

 L. Agassiz; P. lactea Mayer; Aequorea floridana Mayer, 

 among the Leptomedusae; Geryonia proboscidalis Forsk&l; 

 Liriope telraphylla Chamisso and Eysenhardt; Olindias 

 phosphorica tenuis Fewkes; Rhopalonema velatum Gegen- 

 baur, among the Trachy medusae; and Aeginura grimaldii 

 Maas; Cunoctantha octonaria McCrady; Solmundella 

 bitentaculata Quoy and Gaimard (using the names which 

 appear to conform with present usage). 



A goodly number of species, however, do not ap- 

 pear to have been subject to critical review in 

 recent years, so that it is uncertain whether they 

 are good species or merely synonyms of others. 

 Hence, they are not listed at this time. 



LITERATURE CITED 



Bigelow, H. B. 



1913. Medusae and Siphonophorae collected by the U. 

 S. Fisheries steamer Albatross in the northwestern 

 Pacific, 1906. Proc. U. S. Nat. Mus. 44 (1946): 

 1-119, 6 pis., 2 text figs. 



1918. Some Medusae and Siphonophorae from the west- 

 ern Atlantic. Bull. Mus. Comp. Zool., Harvard Col- 

 lege, 62 (8) : 365-442, 8 pis. 



1919. Hydromedusae, siphonophores, and ctenophores 

 of the Albatross Philippine Expedition. Bull. 100, 

 U. S. Nat. Mus. 1 (5) : 279-362, pis. 39-43. 



1938. Plankton of the Bermuda Oceanographic Expedi- 

 tions. VIII. Medusae taken during the years 1929 

 and 1930. Zoologica, New York, 23 (2) : 99-189, 23 

 text figs. 



1940. Eastern Pacific Expeditions of the New York 

 Zoological Society XX. Medusae of the Templeton 

 Crocker and Eastern Pacific Zaca Expeditions, 1936- 

 1938. Zoologica, New York, 25 (3): 281-321, text 

 figs. 1-20. 

 Khamp, P. L. 



1919. Medusae. Pt. 1. Leptomedusae. Danish In- 

 golf Expedition 5 (8): 111 pp., 5 pis., 14 charts, 17, 

 text figs. 



1920. Anthomedusae and Leptomedusae. Rept. Sci. 

 Res. Michael Sars Exped., 1910, Zool. 3 (2): 13 pp., 

 1 pi., 6 text figs. 



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