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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Plexauridae and the Gorgoniidae; while not all of 

 the known West Indian members of these families 

 have been recorded from this area, most are to be 

 expected. This community does not extend 

 northward undiminished for any appreciable dis- 

 tance, although a few of the hardier species range 

 about halfway up the Florida west coast. The 

 scarcity of suitable reef-like situations along this 

 coast seems to account in part for their reduction 

 in numbers, and temperature may be of equal 

 importance in limiting the northward distribution 

 of shallow-water gorgonians. Antillogorgia acer- 

 osa, A. americana, and Pterogorgia anceps are 

 characteristic reef forms which extend some dis- 

 tance up the west coast of Florida, and they 

 probably occur wherever there is solid bottom 

 suitable for attachment and permanent support. 

 The predominant West Indian genera of reef- 

 dwelling gorgonians, Plexaurella, Eunicea, Antil- 

 logorgia, Gorgonia, Pterogorgia, and Phyllogorgia, 

 are restricted to the warm western Atlantic, 

 while a few, such as Pacifigorgia and Muricea, 

 are most numerous on the Pacific coast of the 

 middle Americas, and at least one, Leptogorgia, 

 is found also in the eastern Atlantic, the Mediter- 

 ranean, east Africa, and the East Indies. 



The alcyonarian fauna of the lower west coast 

 of Florida is thus a decimated West Indian as- 

 semblage. To the northward it merges with and 

 soon, perhaps near Tampa, is replaced by a dis- 

 tinctly temperate fauna the predominant gorgo- 

 nians of which are Leptogorgia virgulata and L. 

 setacea (both of which are referable (Bayer 1952) 

 to Verrill's genus Eugorgia), and Muricea pendula. 

 These species are especially abundant along the 

 coast of the Carolinas and south perhaps to north- 

 ern Florida; L. virgulata extends north to New 

 York in moderately deep water, but all three seem 

 to be lacking from the lower east coast of Florida. 

 The short-stemmed sea pansy, Renilla mulleri, is 

 common in the northern Gulf and extends south- 

 ward to Brazil ; it likewise occurs along the Pacific 

 Coast from Central America to Chile. It has not 

 been recorded from the Atlantic coast of North 

 America where the only species appears to be 

 Renilla reniformis, the common long-stemmed sea 

 pansy. The latter species occurs also in the Gulf 

 of Mexico with a variety extending south to the 

 Straits of Magellan and another in California. 



The shallow-water gorgonian fauna of the 

 northern Gulf of Mexico is clearly identical with 

 but discontinuous from that of the Carolina coast. 

 This interrupted distribution pattern has been 

 pointed out by Deevey (Ecology, vol. 31, No. 3, 

 pp. 334-367, 1950) for some hydroids and other 

 invertebrates and is described for fishes in this 

 volume (Rivas, p. 503). Deevey suggests that re- 

 duced temperature during periods of glaciation 

 permitted continuity of the cool-water fauna 

 around south Florida, but it would seem fully as 

 plausible that this continuity existed when Flor- 

 ida was submerged and that subsequent dispersal 

 around the peninsula has been prevented by a 

 thermal barrier. Since apparently favorable situ- 

 ations exist all along the east coast of Florida, 

 the southward dispersal of these discontinuously 

 distributed gorgonians is probably not limited by 

 bottom conditions but by some other environ- 

 mental factor of which temperature seems to be 

 the most likely. In any event, it can hardly be 

 doubted that the present-day distribution re- 

 flects a former continuity of the Gulf and Caro- 

 lina faunas, but a satisfactory explanation must 

 await the study of some group with an extensive 

 fossil record. 



Although its southern limit is not known, the 

 shallow water temperate assemblage is probably 

 present along most of the Texas coast, somewhere 

 along the coast of Mexico mingling with and giving 

 way to the hardier elements of the West Indian 

 fauna which encroach upon it from the south. 

 At least one gorgonacean, Leptogorgia setacea, ex- 

 tends as far south as the Guianas and Trinidad. 



The presence of actively growing coral reefs 

 at Veracruz and along the coast of Yucatan has 

 long been recognized, but the composition of their 

 fauna is little known. Heilprin (1890) reports 

 only one species of gorgonian from the Veracruz 

 reefs and remarks that the vast gorgonian sea 

 gardens so tj'pical of the Bermudas are lacking. 

 The single species that he records, Plexaura 

 flexuosa, belongs to the West Indian fauna, and 

 it seems hkely that other West Indian species 

 occur there. Heilprin notes further that Xiphi- 

 gorgia (now Pterogorgia) anceps was found at 

 Progreso, Yucatdn, another record indicative of 

 the West Indian fauna. The occurrence of the 

 West Indian reef species Gorgonia flabellum on 



