Distribution and natural history notes on Tachymenis chilensis chilensis ( Schlegel , 1837 ) ( Reptilia : Serpentes : Dipsadidae ) in Argentina

Tachymenis is a snakes genus inhabiting western South America, from coastal to Andean regions of Peru, Chile and western Bolivia and Argentina (Walker 1945; Myers and Hoogmoed 1974). The genus contains six recognized species: T. affinis Boulenger, 1896, T. attenuata Walker, 1945, T. chilensis (Schlegel, 1837), T. elongata Despax, 1910, T. peruviana Wiegmann, 1835, and T. tarmensis Walker, 1945 (Walker 1945; Peters and Orejas-Miranda 1970; Ortiz 1973; Uetz and Etzold 1996). A seventh described species, Tachymenis surinamensis Dunn, 1922, was synonymized with Philodryas elegans (Tschudi, 1875) by Myers and Hoogmoed (1974). Tachymenis chilensis is distributed in Chile and Argentina, and is recognized to possess two subspecies (Ortiz 1973, Valenzuela-Dellarossa 2010): the northern T. c. coronellina (Werner, 1898) and the southernmost subspecies in the genus T. c. chilensis (Schlegel, 1837). This species is a small, rare, and scarcely known snake, whose distributional range required revision (Simonetti 2001). Additionally, T. chilensis was considered a Vulnerable species in Chile (Simonetti 2001; Vergara et al. 2008) and Argentina (Vidoz et al. 2011). Recently, Valenzuela-Dellarossa et al. (2010) revisited the distribution of T. chilensis subspecies in Chile, so most of the known information about morphology, biogeography and natural history of the species was published based on Chilean population studies (e.g., Walker 1945; DonosoBarros 1966; Ortiz 1973; Greene and Jaksic 1992; Simonetti 2001). In Argentina, data on the distribution of T. chilensis is scarce and imprecise without voucher specimens (e.g. Cei 1986; Giraudo and Scrocchi 2002; Scolaro 2005; but see Ortiz 1973; Scrocchi et al. 2010 and APN 2011 for precise localities). In this contribution we revisited the distribution of T. chilensis in Argentina based on the study of existing specimens in museums (Museo Argentino de Abstract: We revisit the distribution and natural history data of Tachymenis chilensis chilensis (Schlegel, 1837) in Argentina based on compiled and novel records, extending its northern and southern distribution from the previously known localities in Argentina. We recorded two prey items in Argentinean populations: Rhinella rubropunctata, reported for the first time, and Liolaemus pictus. Tachymenis c. chilensis is mainly found in forested habitats, generally near wetlands with abundant populations of amphibians. The latitudinal range occupied by T. c. chilensis in Argentina is similar to that in Chile, but its northern distribution limit reaches the lowest latitudes in Chile. This is probably due to the higher humidity levels in the western slopes of the Andes and the barrier effect of the highest mountain ranges in this area. 1 Instituto Nacional de Limnología (CONICET, UNL). Ciudad Universitaria, 3000. Santa Fe, Argentina. 2 Facultad de Humanidades y Ciencias (UNL). Santa Fe, Argentina. 3 Administración de Parques Nacionales, Parque Nacional Lago Puelo 9211. Lago Puelo, Chubut, Argentina. 4 Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (CONICET), División de Herpetología. Ángel Gallardo 470. CP C1405DJR. Buenos Aires, Argentina. * Corresponding author. E-mail: alejandrogiraudo@hotmail.com Alejandro R. Giraudo 1,2*, Félix Vidoz 3, Vanesa Arzamendia 1, 2 and Santiago J. Nenda 4 Distribution and natural history notes on Tachymenis chilensis chilensis (Schlegel, 1837) (Reptilia: Serpentes: Dipsadidae) in Argentina

Distribution and natural history notes on Tachymenis chilensis chilensis (Schlegel, 1837) (Reptilia: Serpentes: Dipsadidae) in Argentina Ciencias Naturales "Bernardino Rivadavia" (MACN), Museo de La Plata (MLP) and, Fundación Miguel Lillo (FML)).The other specimens listed here were not collected because this is considered a threatened species in Argentina (Vidoz et al. 2011), although all records were confirmed by us through photographs and direct observation in the field.Identifying T. chilensis in Argentina is unequivocal because it is probably the only species of snakes living in the Patagonian forests and all possible sympatric species are very different in morphology and coloration patterns (i.e.Bothrops ammodytoides, Lystrophis semicinctus, Micrurus pyrrhocryptus, Philodryas patagoniensis, P. psammophidea, P. trilineata, Pseudotomodon trigonatus) (see color patterns and identification guides in Cei 1986;Scolaro 2005;Scrocchi et al. 2010).Additionally, we provided the first natural history observations on Argentine populations, including observations on reproduction, diet, and habitat use.
In agreement with the literature about Chilean populations (Walker 1945;Greene and Jaksic 1992), we recorded the same prey type in Argentinean populations.
One individual of T. c. chilensis (number 35 in Table 1) was observed swallowing the entire body of an amphibian (Rhinella rubropunctata), observed to be protruding from the mouth of the snake (FV pers.obs.).Another specimen (FML 1555, male SVL = 350 mm, TL = 70 mm) had a partially digested lizard (Liolaemus pictus with a total length of 120 mm) in its stomach.The direction of ingestion for the two recorded prey individuals was headfirst.Prior to this study, Rhinella rubropunctata (Bufonidae) had not been recorded as a prey species of Tachymenis chilensis (Walker 1945;Greene and Jaksic 1992), nevertheless, toxic bufonids were cited as prey species of other members of the genus Tachymenis (Walker 1945).We recorded four Argentinean and two Chilean gravid females (Table 2).Litter size observed in our study ranged from six to twelve embryos.Two gravid females (MACN 9332 and 14317, Table 2) showed well-developed embryos without calcified shell, covered by a thin transparent membrane, a morphological evidence that supports the viviparity of the subspecies T. c. chilensis (Yaron 1985).This reproductive mode was indicated for the species by Walker (1945).
Our data (N = 21) indicated that T. c. chilensis inhabits mainly forested habitats (67%, N = 14), including several types of primary and secondary forests, with some records in rivers or lagoon banks (19%, N = 4), gardens (9%, N = 2) and grassland (5%, N = 1), but frequently near to forest patches (Table 1).The northernmost specimen in Argentina (number 1 in Table 1), was observed along a river bank of the arid steppe in the northern parts of Neuquén province, showing the possibility that T. c. chilensis survives in drier conditions associated with wetlands, such as was reported in others northern Tachymenis subspecies or species (Walker 1945;Donoso-Barros 1966;Greene and Jaksic 1992;Vergara et al. 2008).Several individuals of T. c. chilensis were observed close to wetlands (rivers, streams, lagoons, lakes) with abundant populations of amphibians   (Table 1), their main prey (Greene and Jaksic 1992).The compiled data presented here shows that T. c. chilensis inhabits forested habitats, generally near wetlands, from moderate (200 m a.s.l.) to elevated altitudes in Argentina, with the maximum elevation recorded at 2000 m a.s.l. in the northernmost locality (Table 1).
The latitude range occupied by T. c. chilensis in Argentina is similar to that in Chile, coinciding with its southernmost distributional limit (Figure 1; Valenzuela-Dellarossa et al. 2010).However, near its northernmost distributional limit, T. c. chilensis reaches lower latitudes in Chile (34°22' S) than in Argentina (36°24'30" S).This is probably due to the higher humidity levels in the western slopes of the Chilean Andes, and the extreme arid conditions in the eastern Argentinean Andes, were occurred the northern distribution of T. c. chilensis (Villagrán and Hinojosa 2005).Additionally, the northernmost distribution of the subspecies in Chile coincides with the highest mountain ranges of the Andes, near Aconcagua Mountain (6962 m a.s.l.), which probably constitute an effective dispersion barrier in these latitudes, between the Chilean and Argentinean populations of T. chilensis.
In conclusion, our data show that T. c. chilensis has a wider distribution than previously known in Argentina, and we provide the first data on its natural history (habitat use, reproduction and diet) in this country.This study can provide information to better understand the requirements and distribution of Tachymenis chilensis and to implement conservation strategies of this "species categorized as Vulnerable in Argentina".

Figure 1 .
Figure 1.Distribution map of Tachymenis chilensis chilensis showing localities compiled by us (Grey circles), northernmost data from Chile (Black squares) and the continuous distribution in Chile (Red area) following Simonetti (2001) and Valenzuela-Dellarossa et al. (2010).The green open circle shows the previously known distribution in Argentina mapped byCei (1986).