WILLIAMS: CHASMODES TAXONOMY


territories by the two males after introduction into the aquarium. In my
experiment I did not have the facilities to simulate their natural habitat
properly. Forcing them together in the confinement of a small aquarium
could have altered any natural isolating mechanisms that might effectuate
genetic isolation in their natural environment.
 A more extensive analysis of this problem using large saltwater pools
 with both grassbed and oyster reef habitats should provide additional
 insight toward an understanding of the natural isolating mechanisms main-
 taining the genetic integrity of these species.
 SUMMARY
 Two valid species are included in the genus Chasmodes and a new
subspecies is described from the northern Gulf of Mexico. C. saburrae is
found from Edgewater, Florida, southward around the tip of Florida,
northward and westward to the Chandeleur Islands, Louisiana. The second
species, C. bosquianus, consists of two allopatric subspecies, C. b. bosqui-
anus inhabits the Atlantic seaboard from Maryland to Marineland, Florida,
and C. b. longimaxilla subsp. nov. is found from Pensacola, Florida, to
Veracruz, Mexico. The new subspecies is differentiated from the Atlantic
form by its decreased number of small upper pharyngeal canines in adults,
a longer maxillary length, and a modally lower number of gill rakers.
 Character displacement in the area of sympatry in the Gulf appears to
be contributing to the divergence of the two populations of Chasmodes
bosquianus.
 Zoogeography of the genus Chasmodes is discussed and Springer's
(1959) hypothesis is summarized. This hypothesis provides the simplest
explanation for the evolution of C. saburrae, suggesting that it evolved as
an island endemic. Geological views on the timing of the submergence and
emergence of peninsular Florida are discussed in relation to the disjunct
populations of C. bosquianus. The simplest explanation is that the disjunc-
tion originated with the emergence of peninsular Florida, but gene flow
between the disjunct populations has occurred as recently as the last glacial
period by means of southward dispersal due to lowered water tempera-
tures (Walters and Robins 1961).
 Results from hybridization experiments were inconclusive with regard
to determination of the taxonomic status of the species currently recog-
nized in the genus Chasmodes. Additional hybridization experiments
combined with an experimental analysis of habitat partitioning should
provide further insight into the relationship between the sympatric
populations.

 LITERATURE CITED
Alt, D., and H. K. Brooks. 1965. Age of the Florida marine terraces. J. Geol. 73(2):406-411.