88 



S.B. HEDGES 



about the only characters that distinguish these two species are body 

 size and aspects of coloration (e.g., neckband in T. celiae and higher 

 number of body spots). In case the reader is wondering, the presence 

 of enlarged ova in the small holotype of T. celiae, and details of the 

 pattern, indicate it is not a juvenile T. melanurus (Hedges et ah, 

 1999). 



In cluster (3), there are no molecular data available for T. 

 galacelidus and T. hardyi to confirm their species group association 

 with T pardalis. However the association is supported by the fact 

 that there are no diagnostic (non-overlapping) scale or pattern 

 characters that distinguish T. hardyi and T. pardalis. This problem 

 was noted in the original description (Schwartz & Garrido, 1975). 

 However, T. hardyi has a higher number of ventrals, even though 

 overlapping with T. pardalis, and it is a larger species with a 

 distinctly smaller head. The latter character caused Schwartz and 

 Garrido to associate (as a subspecies) T. hardyi with the small- 

 headed T. nigriventris. The third sympatric species of this trio, T. 

 galacelidus, can be distinguished from the other two species by its 

 higher number of ventrals, dorsal spots, and spot rows (all non- 

 overlapping). 



In the case of cluster (4), DNA sequence evidence place all three 

 together as close relatives. Tropidophis fuscus and T. pilsbryi have 

 no completely diagnostic scale differences, although the combina- 

 tion of ventral scale counts and midbody scale rows will distinguish 

 the species. Also, T. fuscus has a more gracile body shape. The third 

 species, T. wrighti, is diagnosed from the other species by its higher 

 ventral counts, and fewer dorsal spots and spot rows (all non- 

 overlapping). 



To summarize, of the ten combinations of closely related, sympatric 

 species, nearly all were distinguished by at least two non-overlap- 

 ping differences in colour pattern, or (less frequently) body 

 proportions. In addition, there was usually one other difference 

 (either non-overlapping or overlapping) in scalation. More distantly 

 related species of Tropidophis often have two (or more) non-over- 

 lapping differences in scalation, in addition to any other differences. 

 This suggests a temporal sequence in character differentiation, with 

 colour pattern and body proportion differences accruing first, fol- 

 lowed by scalation differences. Ideally, one would like to use 

 molecular data as well for assessing differentiation, although tissue 

 samples still are not yet available for many taxa. Using this morpho- 

 logical criterion for assessing species status in Tropidophis, I will 

 now review the current status of the taxa in this genus. 



Hispaniola 



Only one species (T haetianus), with three subspecies, occurs on 

 Hispaniola: T h. haetianus (most of island), T h. hemerus (distal 

 portion of the Tiburon Peninsula in Haiti) and T. h. tiburonensis 

 (extreme eastern portion of the Dominican Republic). Although 

 Schwartz and Marsh (1960) and Schwartz (1975) have considered 

 the Jamaican taxa to be subspecies of T haetianus, genetic evidence 

 has shown that they are more closely related to the Cuban species 

 (Hass, Maxson & Hedges, 2001) and thus are removed from T 

 haetianus (see below). Also, the Cuban specimens of T haetianus 

 discussed by Schwartz and Marsh (1975) and Schwartz and Garrido 

 (1975) have been removed from that species and assigned to a new 

 species, T hendersoni (Hedges & Garrido, 2002). Because the 

 subspecies of Hispaniolan T haetianus are parapatric and apparently 

 intergrade (Schwartz, 1975), and because their character differentia- 

 tion is less than that of sympatric species, I suggest retaining their 

 current taxonomic status as subspecies. It is possible that genetic 

 studies in the future may further clarify their status. Thus, T. 

 haetianus is confined to Hispaniola and contains three subspecies. 



Navassa Island 



Four specimens of T bucculentus are known from this small island 

 between Hispaniola and Jamaica, but apparently no snakes have 

 been seen in over 1 00 years and thus the species is considered extinct 

 (Powell, 1999). Since it was described by Cope (1868), there has 

 been considerable confusion as to its species status and relationship 

 with other species. Most who have examined the type series, includ- 

 ing me, have noted a resemblance to T melanurus (Thomas, 1966), 

 although Stull ( 1 928) instead considered it a subspecies of T pardalis. 

 There is no overlap in ventral counts between T bucculentus and T 

 melanurus, and almost no overlap in caudal counts. Although there 

 appear to be pattern differences between the two species, the single 

 specimen in the Academy of Natural Sciences (Philadelphia) differs 

 from the other three specimens (National Museum of Natural His- 

 tory, Smithsonian) in terms of ventral pigmentation (Bailey, 1937). 

 Based on the diagnostic scalation differences alone, I would con- 

 sider T. bucculentus as a valid species. The unusual geographic 

 location of a species with apparent Cuban affinities, on Navassa 

 Island, is remarkable. With the exception of the anole (Anolis 

 longiceps), other species on Navassa have affinities with nearby 

 Hispaniola (Powell, 1999; Thomas, 1966), which is logical based on 

 the westerly direction of ocean currents. However, the eastern tip of 

 Cuba is further east than Navassa. and ocean currents flow southerly 

 through the Windward Passage separating Cuba and Haiti. Dispersal 

 on those currents is thus possible and is the most likely explanation 

 for the origin of T bucculentus (and A. longiceps) on Navassa and 

 possibly the gecko Sphaerodactylus notatus on the Morant Cays 

 southeast of Jamaica. The locally changing direction of water 

 currents during a hurricane may also have aided in the dispersal of 

 these taxa. 



Cuba 



With 15 described species. Cuba is the hot spot of species diversity 

 in the genus. Recently, two subspecies described by Schwartz and 

 Garrido (1975) were elevated to species status and a new species 

 was described from eastern Cuba (Hedges & Garrido, 2002). 

 Character differences among many of the Cuban species have been 

 discussed above (see 'Species Boundaries'), and I consider all 15 

 species to be valid. Also, I am aware of material that likely repre- 

 sents additional, undescribed species. Undoubtedly, more species 

 will be discovered. 



Two remaining taxa are considered subspecies of T. melanurus: T. 

 m. dysodes and T m. eriksoni (Schwartz & Thomas, 1960). The 

 former is known from three female specimens from near La Coloma, 

 Pinar del Rio Province, and the latter is restricted to Isla de Juventud. 

 These taxa differ from T. m. melanurus primarily in size of the dorsal 

 spots and in having bolder, darker colouration, with T. m. dysodes 

 having the darkest pigmentation of the three subspecies. The ventral 

 counts of T. m. eriksoni are low for the species, but there is 

 considerable overlap with the other two taxa. Considering that there 

 are no diagnostic differences in body proportion or scalation, and the 

 colouration differences, although real, are not as trenchant as those 

 distinguishing sympatric. closely related species (e.g., T maculatus 

 and T. semicinctis), I am inclined to leave their status as subspecies 

 unchanged until additional data warrant a reconsideration. 



Jamaica 



The three Jamaican taxa, originally described as full species, are 

 closer to Cuban taxa than to T. haetianus based on immunological 

 data (Hass et al, 2001) and DNA sequence data (S. B. Hedges, S. C. 

 Duncan, A. K. Pepperney. in preparation). However, they form a 



