18 



Hydrodynastes gigas (Dumeril, Bibron & Dumeril, 1854) 



Xenodon gigas Dumeril, Bibron & Dumeril, 1854. Erp. Gen., 7:761. 



Cyclagr as gigas Cope, 1885. Proc. Amer. Phil. Soc. 22: 185. 



Hydrodynastes gigas Hoge, 1966. Cienc. Cult. 18 (2): 173. 

 Type locality: Corrientes province, Argentina. 



Distribution: Buenos Aires, Corrientes, Chaco, Entre Rios, Formosa, Misiones and Santa Fe. Also Perii, 

 western, central and southeastern Brazil, eastern Bolivia and Paraguay (Williams & Scrocchi, 1994; Moura 

 Leite et al., 1996; Giraudo & Quaini, 1997; Bemarde & Moura Leite, 1999). Chaquena province and 

 bordering areas of Paranaense and Espinal provinces in large rivers. Always associated with aquatic 

 environments. 



Hydrops Wagicr, 1830 



Hydrops Wagler, 1830. Nat. Syst. Amph.: 170 



Higina Gray, 1842. Zoological Miscellany: 67 

 Type species: Elaps martii Wagler, 1824. by subsequent designation, Fitzinger, 1843: 25 

 Comments: As Giraudo (1997) summarized, Williams & Couturier (1984) cited for the first time Hydrops 

 triangularis bolivianus from Argentina in Bella Vista, Corrientes, saying that it was impossible to identify 

 the individual using the key of Roze (1957) and that the major difference with H.t. triangularis is coloration, 

 mainly the number and form of dark dorsal bands. Nevertheless, the specimen was referred to H. t. 

 bolivianus in that work and in later lists of Argentinian snakes (Williams & Francini, 1991; Cei, 1993; 

 Williams & Scrocchi, 1994). Alvarez & Aguirre (1995) described another individual from Yacyreta, 

 Corrientes and indicated that it belongs to the same taxon than the one of Bella Vista (Corrientes). However, 

 faced with the differences in pattern with H. t. bolivianus (the most important character to differentiate the 

 subspecies, Roze, 1957), they preferred not to assign it to subspecies. There is no basis to assign the 

 Argentinian and Paraguayan populations to bolivianus, because the variation of the subspecies is unknown. 

 Roze described bolivianus using only two individuals from the Bolivian Beni, thousand of kilometers away 

 from Argentinean-Paraguayan populations. 



The specimen mentioned by Alvarez & Aguirre (1995), (UNNEC 409), was examinated by us and the 

 differences in pattern with all the subspecies of Hydrops triangularis (Roze, 1957) are great. The populations 

 of northeastern Argentina should be revised, as they may be a new subspecies or even species. Until more 

 specimens can be studied, this taxon is retained as Hydrops triangularis. 



Hydrops triangularis (Wagler, 1824) 



Elaps triangularis Wagler, 1824. In Spix, Sp. Nov. Serp. Bras.: 5, pi. 2a, fig. B. 



Hydrops [triangularis] Wagler, 1830. Nat. Syst. Amph.: 170. 

 Type locality: Ega (= Tefe), Tefe Lake in the confluence with Amazon River, Brazil. 



Distribution: Corrientes (Williams & Couturier, 1984; Alvarez & Aguirre, 1995). Also in the Yacyreta area 

 on the border between Paraguay and Argentina (Aquino et al., 1996). Paraneanse province, all the records in 

 the Parana River. The species is distributed from Venezuela, the Guianas and Trinidad to eastern Peni, 

 Brazilian Amazonia and northern Bolivia (Roze, 1957; Peters & Orejas Miranda, 1970). Also in Maranhao 

 and Piaui (Zhaer & Caramaschi, 1996; Yuki, 1997). 



Imantodes Dumeril, 1853. 

 Imantodes Dumeril, 1853. Mem. Acad. Sci. Paris, 23: 507. 



Himantodes Cope, 1860. Proc. Acad. Nat. Sci. Phila., 1860: 264. Emendation of Imantodes Dumeril. 

 Type species: Coluber cenchoa Linnaeus, 1758, by monotypy. 



Comments: Although some authors mentioned Imantodes cenchoa cenchoa from Argentina, Myers (1982), 

 in a revision of the genus, indicated that there is great overlap in the characters used to separate subspecies 

 and argued that subspecies are not valid. Vanzolini (1986) expresed the same opinion. 



Imantodes cenchoa (Linnaeus, 1758) 

 Coluber CenchoahmmLeus,ll5S. Syst. Nat. Ed. 10:226. 



Bungarus cencoalt Oppel (error to cenchoa Linnaeus), Ann. Mus. Hist. Nat. Paris 16: 392. 

 D.[ipsas] Weigelii Fitzinger (sustitutive name to cenchoa Wied, that is the same as cenchoa of 



