24 



Markezich, 1992; Lavilla et al., 1995; Giraudo, 1997). Extensive South American distribution from 

 southeastern Venezuela and western Guyanas, in Brazil, Bolivia, Paraguay, Uruguay and Argentina east of 

 Andes (Dixon 1989, Dixon & Markezich, 1992; Achaval & Olmos, 1997). 



Comments: As Dixon & Markezich (1992) commented, this taxon is very complex. Undoubtedly, it is one 

 of the most remarkable examples of geographic variation in Neotropical snakes. 



Dixon & Markezich (1992) studied the variation and in the majority of the analyzed populations, they did 

 not find significant differences in meristic characters. Using the color pattern variation, they recognized four 

 subspecies: L. p. poecilogyrus in the Atlantic Forest of Rio de Janeiro and Espiritu Santo; L. p. caesius in the 

 Chacoan Biogeographic region; L. p. schotti with an extensive distribution in the Catingas, Cerrado, part of 

 Amazonian Region and Paranaense Forest; and L. p. sublineatiis in the Pampean areas. However, they 

 recognized different patterns and the presence of geographic clines in meristic and coloration characters 

 within the subspecies. 



Giraudo (1997) studied a great number of specimens froin different areas of Argentina and identified them 

 at subspecific level according to the Dixon & Markezich (1992) key. He concluded that the polymorphism of 

 Argentinian populations is greater than that suggested by Dixon & Markezich (op. cit.) and that the limits 

 between subspecies are arbitrary. Some specimens can be identified easily but others show characters from 

 two or more subspecies. 



Giraudo (1997) concluded that one taxon has a very regular pattern (with ontogenetic variation) in 

 Misiones and northeastern Corrientes and exhibits some patterns described for L. p. schotti by Dixon & 

 Markezich (1992). In northwestern Corrientes, this taxon intergrades with L. p. caesius and L. p. sublineatus. 

 Considerable variation can be found in this area, but predominantly, the forms are similar to caesius. Also, 

 intergrades of caesius-sublineatus and caesius-schotti can be found; a few specimens have a pattern similar 

 to sublineatus. 



In Salta, Formosa, western Chaco and northern Santa Fe, associated with the xerophytic forests of 

 Chaquefia province, there is a population with a characteristic pattern (although it is also variable), that can 

 be assigned to L. p. caesius. An example of this is the specimen photographed in Lavilla et al. (1995). This 

 subspecies was not included in Argentina by Cei (1993). This taxon intergrades with schotti towards the east 

 and with sublineatus towards the south. 



Finally, in Buenos Aires, Cordoba, southern and central Santa Fe, there are populations that can be 

 assigned to sublineatus that present a typical color pattern, but they are also very variable. These populations 

 intergrade with caesius in central and northern Santa Fe and Santiago del Estero. 



As the above subspecies have clear biogeographic patterns that can be of importance in evolution and in 

 conservation studies, we use the approach of Dixon & Markezich (1992) but point out to the users of the 

 present list that there are wide areas of intergradation and that the populations show high variability. 

 Therefore, in many cases, the identification at subspecific level is an illusion. 



Liophis poecilogyrus caesius (Cope, 1862) 



Opheomorphus doliatus caesius Cope, 1862. Proc. Acad. Nat. Sci. Philadelphia 1862: 348. 



Leimadophis poecilogyrus reticulatus Parker, 1931. J. Linn. Soc. London 37: 285, pi. 16. 



Liophis poecilogyrus Dixon, 1980 (partim). Milwaukee Public. Mus., Contr. Biol. & Geol. 31:13. 



Liophis poecilogyrus caesius Dixon & Markezich, 1992. Texas Jour. Sci. 44 (2): 151. 

 Type locality: Santa Fe, Argentina. 



Distribution: Chaco, northeastern Corrientes, Formosa, Salta, Santiago del Estero, northern Santa Fe and 

 Tucuman (Dixon, 1989; Dixon & Markezich, 1992; Lavilla et al., 1995; Giraudo, 1997). Also Bolivia, 

 Paraguay, Uruguay and Argentina (Dixon 1989, Dixon & Markezich, 1992; Achaval & Olmos, 1997). 

 Mainly Chaquefia province. 



Liophis poecilogyrus schotti (Schegel, 1837) 

 X.[enodon] Schotti Schegel, 1837. Essai Physion. Serpens, 2: 91. 

 Liophis ornatissima Jan, 1863. Arch. Zool. Anat. Fisiol. 2: 123-330. 

 Liophis typhlus gastrosticta Jan, 1863. Arch. Zool. Anat. Fisiol. 2: 123-330. 

 Liophis typhlus olivacea Jan, 1863. Arch. Zool. Anat. Fisiol. 2: 123-330. 

 Liophis verecundus Jan, 1863. Arch. Zool. Anat. Fisiol. 2: 123-330. 

 Liophis cobella flaviventris Jan, 1863. Arch. Zool. Anat. Fisiol. 2: 123-330. 



