Dipsas viguieri

The Distributional Status of Dipsas viguieri Peters (1960) reviewed the taxonomic status of members of the subfamily Dipsadinae, and placed nine species in the Dipsas articulata group, collectively distributed from western and southeastern Mexico to northwestern Ecuador. Peters’ view of the species-level relationships among the members of the articulata group was impacted by the paucity of specimens of each taxon known at that time, and he noted that only minimal scale and color differences separated certain species. Peters (1960) indicated the range of D. viguieri as the Pacific coast of Panama. Pérez Santos and Moreno (1988) reported on a specimen of D. gracilis from the Pacific coast of Colombia (see discussion below), and Pérez Santos (1999) noted the occurrence of D. viguieri from both versants of Panama, including a specimen from the province of Bocas del Toro in the western part of the country. Subsequently, Köhler (2001; 2003; 2008) noted the range of Dipsas viguieri as eastern Panama and western Colombia but did not provide additional information. Cadle (2005), in a paper on the systematics of the Dipsas oreas complex, tentatively referred to a specimen (FMNH 74376) from northwestern Colombia near the Panama border as D. viguieri, which previously had been identified as D. gracilis. Nonetheless, Cadle (2005) stated that these two taxa were not distinguishable by any reported characteristics, and on p. 128 noted that, “Without additional study, I am unable to adequately differentiate Dipsas viguieri (eastern Panama and northern Chocó, Colombia) and D. gracilis (western Ecuador and extreme northern Peru).” Further, based on an examination of morphological characters, Cadle indicated geography as the only currently reliable means of assigning names to these species. Similarly, in discussing a number of poorly-known Dipsas from South America, Harvey (2008) commented that he was unable to distinguish D. viguieri from D. gracilis, and thus did not include D. viguieri in his key but noted that the D. articulata complex requires further study. Jaramillo et al. (2010) and Johnson et al. (2015) regarded Dipsas viguieri as endemic to Panama. Wallach et al. (2014: 235), however, considered D. viguieri as occupying “Eastern Panama (Canal Zone, Darién, Panamá) and Colombia (? Chocó, Piura), NSL– 60 m. ” In their D. gracilis account, however, these authors noted, “Colombian record doubtful fide Cadle (2005: 123): possibly D. viguieri. Dipsas gracilis and D. viguieri possibly conspecific fide Harvey (2008: 429).” Wallach et al. (2014: 232), however, apparently confused the information provided by Cadle (2005), as the FMNH specimen tentatively was referred to D. viguieri and not D. gracilis. Finally, Ray (2017) indicated the range of D. viguieri as eastern Panama to northwestern Colombia. The historical timeline for information on the distribution and taxonomic status of Dipsas viguieri has been unclear, as different workers have maintained that this species is endemic to Panama or occurs in both Panama and Colombia. In the absence of a definitive analysis involving morphological and molecular approaches, for the purpose of this paper we are considering D. viguieri as not endemic to Panama. Global Status of the Central American Herpetofauna As with the Mexican herpetofauna (Johnson et al. 2017), the Central American herpetofauna also is highly diverse, consisting of 60 families, 214 genera, and 1,095 species (Table 1), organized into six orders (Anura, Caudata, Gymnophiona, Crocodylia, Squamata, and Testudines). The level of herpetofaunal diversity in Central America is intermediate between that found in Mexico and North America (United States – Canada). The number of species in the United States – Canada is the same as Johnson et al. (2017) reported, i.e., 650 (Center for North American Herpetology website; accessed 9 December 2017). Johnson et al. (2017) reported the number of species in Mexico as 1,292. Even though the number of herpetofaunal species occurring in Central America is intermediate between that found in the United States – Canada and Mexico, Central America contains about 8.5 times the number of taxa by area as found in Mexico, and 155.6 times the number found in the United States – Canada. Thus, the relative degree of biodiversity is significantly higher in Central America when compared to that in Mexico and the United States – Canada. If we consider Central America as a single region in our analysis (i.e., not one divided into seven countries), then its herpetofauna also is significant when compared to that of other areas in Latin America. With respect to amphibians, the 509 species occurring in Central America is the fifth largest in Latin America (amphibiaweb.com; 15 April 2018), and is closest to that for the country of Ecuador, at 562. The area /species ratio for Ecuador however, is 504.6, compared to 998.0 for Central America. Considering the numbers of crocodylian, squamate, and turtle species, the 586 species in Central America is comparable to that recorded for the neighboring country of Colombia, which is 611 (reptile-database.org; accessed 29 December 2017). Colombia, however, with an area of 1,141,748 km 2, is 2.25 times the size of Central America, which contains an area of 507,966 km 2 (www. Oei.es/ historico/cultura2/ Colombia /03.htm; accessed 29 December 2017). Thus, the area/species ratio for Colombia is 1,868.7, compared to 868.0 for that of Central America. Only Brazil (799) and Colombia in South America contain more species than Central America (reptile-database.org; accessed 29 December 2017). Endemism within the Central American Herpetofauna The proportion of herpetofaunal endemism in Central America is slightly less than in Mexico, the other major segment of Mesoamerica. The percentage in Central America is 56.9 (Table 2) compared to 61.1 in Mexico (Johnson et al. 2017). This percentage in Central America is based on an endemic herpetofauna of 623 species and a total herpetofauna of 1,095 species (Table 2). Both of the comparable figures for the Mexican herpetofauna are higher, i.e., 789 and 1,292 (Johnson et al. 2017). As noted by Johnson et al. (2015: 26), “Mesoamerica is one of the world’s most important biodiversity reservoirs, and Central America contains a substantial component of that region’s herpetofauna.” We illustrate the breakdown of the total and endemic components of the Central American herpetofauna in Fig. 1. This graph shows the close correspondence between the endemic and total number of salamander species, the relatively distant correspondence between the endemic and total number of squamate species, and the intermediate correspondence between the two figures for anurans (Fig. 1). Of the 60 families represented in Central America, 38 (63.3%) contain endemic species (Table 2). This leaves 22 families with no endemic representation, including the anuran families Aromobatidae, Hemiphractidae, and Rhinophrynidae, the crocodylian families Alligatoridae and Crocodylidae, the squamate families Amphisbaenidae, Hoplocercidae, Polychrotidae, Xenosauridae, Boidae, Charinidae, Loxocemidae, Natricidae, Sibynophiidae, and Tropidophiidae, and the turtle families Cheloniidae, Chelydridae, Dermatemydidae, Dermochelyidae, Emydidae, Staurotypidae, and Testudinidae. In Central America these are small-content families, with species numbers ranging from one to five (Table 2). The families with endemic representation have total numbers ranging from one to 166; the endemic numbers vary from one to 143 (Table 2). Of the 14 anuran families with representatives in Central America, 11 contain endemic species, which include 192 (58.5%) of the total of 328 species (Table 2). Of these 11 families, the largest numbers of endemics are 77 in the Craugastoridae and 52 in the Hylidae. Other than in the Pipidae, with one total and one endemic species (100%), as might be expected, the percentage of endemism is next highest in the Craugastoridae (75.5%), but the third highest is in the Dendrobatidae (66.7%), and not the Hylidae (60.9%). The value for the Eleutherodactylidae (62.5%) also is higher than that for the Hylidae. The remaining families contain from one to 24 endemic species (Table 2). A single family of salamanders, the Plethodontidae, occurs in Central America. The percentage of endemism (86.1%) is amazingly high and is the highest in all the 38 families represented (Table 2). The endemic species of caecilians (seven) make up less than one-half (46.7%) of the total number of 15 in Central America. Three of the endemics are caeciliids and four are dermophiids. None of the three species of crocodylians in Central America is endemic. Crocodylus acutus and Caiman crocodilus rather are among the naturally most broadly distributed herpetofaunal species in the Western Hemisphere. The squamates are the most speciose group of herpetofaunal organisms in Central America, with 560 species distributed among 32 families (Table 2). Only the endemic proportions of turtles (8.7%) and crocodylians (0.0%) are lower than those of squamates (49.8%). The endemic squamates are more or less evenly divided between the lizards (143) and snakes (136). Of the 19 families of lizards with representatives in Central America, 15 contain endemic species (78.9%). The largest numbers of endemic squamate species are found within the families Dactyloidae (74) and Dipsadidae (77). The next largest number of endemic lizards (25) is allocated to the family Anguidae. The remaining 12 lizard families contain only one to 13 endemic species. The percentage of endemism among the lizard families ranges from 11.1% in the Corytophanidae to 80.0% in the Mabuyidae (Table 2). Thirteen families of snakes are represented in Central America, of which seven contain endemic species (53.8%). The greatest numbers of endemic species are in the families Dipsadidae (77) and Colubridae (30). The

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