New locality records and geographic distribution map of Dendropsophus meridensis ( Rivero , 1961 ) ( Anura : Hylidae ) in the Andes of Venezuela

Dendropsophus meridensis is a medium-sized treefrog endemic to the Cordillera de Mérida in the Venezuelan Andes. The geographic distribution of this species is poorly known, and only 10 localities known in the literature. Most of these localities do not have associated geographic coordinates and altitude. In this note we provide eight new locality records and a geographic distribution map of D. meridensis, based on field work, revision of Venezuelan museum collections, and species distribution modeling. Three of these new localities were found after performing species distribution modeling. Additionally, some comments on natural history and color variation are included.

The genus Dendropsophus Fitzinger, 1843 currently comprises 99 valid species (AmphibiaWeb 2014) and is distributed from Mexico to Uruguay and northern Argentina (Frost 2014).About 23% inhabit highlands (>1,000 m) of the northern Andes.In Venezuela, there are 12 species (Barrio-Amorós 2009), of which Dendropsophus meridensis (Rivero, 1961) is the only species endemic to the Cordillera de Mérida (La Marca 1992).This species is included in the labialis species group (Duellman 1989;Faivovich et al. 2005;Wiens et al. 2010) with D. labialis (Peters, 1863), D. luddeckei Guarnizo, Escallón, Cannatella & Amézquita, 2012, and D. pelidna (Duellman, 1989).The later was suggested to be a junior subjective synonym of D. mer idensis by Guarnizo et al. (2012), but they did not formally propose a taxonomic reassignment because their study lacked robust data.Therefore, we continue to recognize D. pelidna as a valid species and only refer to D. meridensis those populations inhabiting the Cordillera de Mérida, until such time that the taxonomic status of these taxa are clarified.
According to Rivero (1961) and Duellman (1989), D. mer idensis is characterized by having yellow spots in the groin and the hidden surfaces of the limbs, and by being smaller than D. labialis (SVL of males <40 mm; SVL of females >40 mm).
It was described by Rivero (1961) from Mérida (city) and two other localities: La Culata and Chama.La Marca (1994), Barrio (1998), andLa Marca (2004) mentioned eight additional localities, also in the Mérida state: La Mucuy, La Carbonera, La Culata, Monte Zerpa, Páramo de Mucubají, Páramo de El Tambor, Valle Grande, and Vía El Morro.However, only two of these localities were provided with coordinates (Table 1).Den dropsophus meridensis was listed as "Endangered" (EN) by the IUCN Red List (La Marca 2004) because its extent of occurrence is less than 5,000 km 2 and its distribution is severely fragmented, it has a high prevalence of infection of Batra chochytrium dendrobatidis in wild populations (Sánchez et al. 2008), it is sympatric with the introduced species Lithobates catesbeianus (reservoir for Batrachochytrium dendrobatidis) (Villarroel et al. 2013), and there is continuing decline in the extent and quality of its habitat in the Venezuelan Andes.However, based on the poorly known of its geographic distribution and natural history, this species has been categorized as "Data Deficient" (DD) in the Venezuelan Red List (Rodríguez and Rojas-Suárez 2008).
Herein, we provide new records and a geographic distribution map of Dendropsophus meridensis in the Cordillera de Mérida.The data were compiled from: i) examining specimens housed in several Venezuelan herpetological collections (Appendix 1); ii) revising published literature and an online database (http://www.herpnet.org);and iii) field work in some localities of the Cordillera de Mérida.Although the HerpNET database includes a locality at La Grita (based on two specimens collected in 1970 and housed at the USNM), this locality has not been recorded in the scientific literature or by the IUCN; we do not know the reasons why this has happened, but perhaps it is because La Grita is located out Mérida state, far from the historical localities (round the Mérida city), and no one has revised these specimens and verified its locality.
We visited the collections at the Museo de Historia Natural La Salle (MHNLS), Museo de Biología of the Universidad Central de Venezuela (MBUCV), Colección de Vertebrados of the Universidad de los Andes (CVULA), Laboratorio de Biogeografía of the Universidad de Los Andes (ULABG), and Estación Biológica de Rancho Grande (EBRG).Voucher specimens obtained from field work were euthanized in 2% lidocaine solution, fixed in 5% formaldehyde solution, transferred to and kept in 70% ethanol, and deposited in the herpetological collection of the MHNLS under the codes MHNLS 20407-20416, MHNLS 21167-21169.
Complementarily, we performed a species distribution modeling (SDM) (Phillips et al. 2006) in order to infer its potential geographic distribution in the Andean region.This analysis was based on eight localities: seven were obtained from literature and herpetological collections with geographic coordinates when available, and one from our field work.We used 19 climatic variables, which were obtained of the WorldClim Project (Hijmans et al. 2005), and were reduced to 10: Bio2, Bio6, Bio15, Bio3, Bio4, Bio17, Bio7, Bio18, Bio16, Bio14 (see variables names in: http://biogeo.berkeley.edu/worldclim), based on a Pearson correlation test, according to Pearson et al. (2007).
During the field work in the Mérida state, we found two new localities for D. meridensis.On 13 June 2011 ten specimens (three males and seven females) were collected in La Sucia sector, Sierra de Tovar, Tovar municipality, southwestern of Mérida state (08°18ʹ35ʺ N, 071°47ʹ51ʺ W; 2,070 m a.s.l.[above sea level]).These individuals were found in a pond nearby the road Tovar-Páramo de Mariño.In this site, there were some calling males between 19:00 and 20:40 h, of which three were collected.Females captured were around the water body.This locality is about 57 km southwest of the type locality and of the others reported in literature (Table 1, Figure 1).Additionally, we collected three male specimens on 3 October 2012 in San Javier del Valle, Libertador municipality, close Mérida city (08°39ʹ15ʺ N, 071°07ʹ0.98ʺW; 2,000 m a.s.l.).These individuals were in a large artificial pond (about 200 m of diameter), at the Fundación Fe y Alegría.This pond had herbaceous vegetation in its edge where there were many calling males between 17:30 and 20:30 h (none of those were collected).There, we observed also several individuals of Hypsiboas crepitans (Wied-Neuwied, 1824).In this pond was common the presence of buffaloes feeding on pastures.
The SDM predicted an environmental suitability area for D. meridensis including the north slope of the Sierra de La Culata (Cordillera de Mérida), northern the Cordillera de Mérida and part of the Massif El Tamá (Figure 2).The SDM shows the north slope of the Cordillera de Mérida as the area with high probability (>70%) for the presence of D. meridensis, followed by Massif El Tamá (Andes of Colombia and Venezuela) and the northeastern Cordillera de Mérida (Figure 2); with a intermediate probability (40-64%), other areas of the Cordillera de Mérida and the Colombian Andes are shown as potential zones for the presence of D. meridensis (Figure 2).We visited part of the predicted area by the SDM with intermediate probability in the southern the Cordillera de Mérida and found new three localities: two in the Táchira state, and another in the Mérida state (Table 1).In the first of these three sites, on 24 June 2013 we heard several individuals along the road between Las Porqueras and La Grita but it was not possible to recording their calls.On 25 June 2013 we found two individuals calling in a pond the side of the road La Grita-Tovar, at 19:20 h.Of these two individuals, one was collected (MHNLS 21422), which exhibited green color with no spots (Figure 3a).At the same date, we found several individuals calling in a pond near the road at the Sector La M (municipality of Rivas Dávila, Mérida state) at 20:10 h, but they were not collected.With these findings, we confirm the presence of D. meridensis in the estate of Táchira as reported at the HerpNET online database.
The presence of D. meridensis in these new localities is not unexpected due to the characteristics of these localities: open areas and farms with ponds.Our review of collections allowed us to determine the altitudinal distribution of this species (between 1,630 and 2,895 m; Table 1).This species inhabits open and disturbed sites in cloud forest (La Marca 1994), temporary and artificial ponds with abundant grasses, and in pasturelands without nearby forest cover, as reported for other members of the D. labialis species group (see Guarnizo et al. 2012).Although the species has been reported from paramo and subparamo, its presence in these ecosystems is considered as consequence of recent invasion (La Marca 1994).These additional records and the SDM allow filling geographic gaps for D. meridensis, and suggest that it has a larger geographic distribution.The individuals observed by us exhibit greater color variation than previously reported.Green color is predominant as the dorsal background, but some individuals have the dorsum green but mottled with bronze, solid brown or cream.The spots on their inner surfaces of the thighs and groins can be blue with black or yellowish green; these spots may be of different sizes.We also observed that the skin of D. meridensis may be smooth (Figure 3b), as described by Rivero (1961), or with small tubercles (Figures 3c, 3d).
The SDM also predicted the distribution of D. meridensis in the Massif El Tamá, near the type locality of its sister species, D. pelidna, suggesting that both might coexist in this area.Although the taxonomic status of D. pelidna is doubtful and it is possibly synonymous with D. meridensis, according to a recently published study, there yet is not additional evidence to support this for now (Guarnizo et al. 2012).
Our results show that D. meridensis may have a wider geographical distribution and also indicate the usefulness of SDM  to identify suitable in Andean region for exploration.Our new localities for D. meridensis provide the basis for a reassessment of D. meridensis and show that this species is not endemic to Mérida and does not have a restricted range.Moreover, geographical predictions made from small numbers of occurrence records can be of great value, for example, in developing field studies to accelerate the discovery of unknown species and populations (Pearson et al. 2007).This suggests the importance of increasing field work in several areas of the Venezuelan Andes to better understand the true geographical distributions of Andean amphibians.

Figure 2 .
Figure 2. Potential distribution model of Dendropsophus meridensis in the Colombian and Venezuelan Andes.Black points indicate localities used in analyses.

Table 1 .
Locality records of Dendropsophus meridensis.AMNH: American Museum of Natural History; CNHM: Chicago Natural History Museum; CVULA: Colección de Vertebrados of the Universidad de los Andes; MBUCV: Museo de Biología of the Universidad Central de Venezuela; EBRG: Estación Biológica de Rancho Grande; MHNLS: Museo de Historia Natural La Salle; MCZ: Museum of Comparative Zoology, Harvard University; ULABG: Laboratorio de Biogeografía of the Universidad de Los Andes UMMZ: Museum of Zoology of the University of Michigan; USNM: National Museum of Natural History, Smithsonian Institution.
*Revised collections in this study.