Herpetofauna of the Bilsa Biological Station, province of Esmeraldas, Ecuador

: The Bilsa Biological Station is located on the Mache-Chindul mountains and protects some of the last rainforest remnants in the province of Esmeraldas, northwestern Ecuador. Since 2004, we have been inventorying the amphibians and reptiles of Bilsa. We found 109 species of herpetofauna (37 amphibians and 72 reptiles), representing 8 % and 18 % of the known species from Ecuador, respectively. We report distribution extensions for Sachatamia albomaculata , Hyalinobatrachium valerioi , Pristimantis muricatus , and P. rosadoi , and report the presence of several putatively undescribed species. We propose the Mache–Chindul mountains as a Key Biodiversity Area within the West Ecuadorian Endemic Area.

and 09-17 May 2008 (36 hours/person); always at 09:00h-13:00h and 20:00h-23:00h. We prepared voucher specimens only for species that were caught for the first time or presented difficulties for field identification (Appendix 1). Photographic vouchers (but not specimens) were subsequently obtained from February 2004 to January 2009. Measurements were taken with a 0.5 mm precision dial caliper. Anuran calls were recorded with a Sony microcassette-corder M-670V and analyzed with Sound Ruler Acoustic Analysis®, following bioacoustics parameters suggested by Angulo (2006).
We recognize three categories of records: confirmed, unconfirmed, and unidentified species. Confirmed species are those with voucher specimens deposited at the División de Herpetología of the Museo Ecuatoriano de Ciencias Naturales (DHMECN, Quito, Ecuador). Unconfirmed species correspond to species captured and released, but supported by photographic vouchers. Unidentified species correspond to specimens (collected or photographed) still in need of specific verification pending additional collections.

Results and Discussion
Thirty-seven species of amphibians and 72 species of reptiles were recorded in total at the Bilsa Biological Station (Appendix 1-3). The families Colubridae (34 spp.) and Polychrotidae (11 spp.) were diverse in the reptiles assemblage, while the families Hylidae (8 spp.) and Strabomantidae (8 spp.) were the most diverse families for amphibians (Table 1). About 33 % of Bilsa's herpetofauna is rare, with only one specimen registered for each species.
Cochranella mache, globally classified as Critically

Extension ranges
Pristimantis muricatus: This Ecuadorian-endemic species was previously known from six localities in humid lowlands and pre-montane slopes of the provinces of Pichincha and Esmeraldas, Ecuador, at elevations between 60 and 1380 m (Lynch and Duellman 1997;Morales et al. 2002;Figure 4). We collected a female specimen (DHMECN 3652;36.52 mm in SVL) at the White trail on 13 December of 2006 ( Figure 1A). This specimen was about 1 m above the ground on streamside vegetation at night.  Figure 5). Pristimantis rosadoi is a species distributed at Isla Gorgona, Colombia, and northwestern Ecuador, up to 800 m (Lynch and Duellman 1997;Cisneros-Heredia et al. 2004). New material (Figure 4) Morales et al. 2002), and ca. 122 km from the closest southern locality (near to Río Caoní, province of Pichincha; Lynch and Duellman 1997). Based on the records presented herein, the estimated area of occurrence of P. rosadoi is ca. 11,884 km 2 ( Figure 5).
Hyalinobatrachium valerioi ( Figure 4) is widely distributed from central Costa Rica, through Panama and the Pacific lowlands of western Colombia and western Ecuador (Duellman and Burrowes 1989;Cisneros-Heredia and McDiarmid 2007;Solís et al. 2008). We report the first record of Hyalinobatrachium valerioi from the province of Esmeraldas. This record is the westernmost locality of the species, ca. 186 km from the nearest locality (Maldonado, province of Carchi, Duellman & Burrowes 1989) and ca. 116 km from the most southeastern locality (Centro Científico Río Palenque, province of Pichincha; Figure  7). A male ( Figure 4) was recorded, but not collected, on the underside of a Heliconia leaf, 2.5 m above ground, near the Duchas stream at night on 27 January 2008. A metamorphic individual was observed in the Aguacatal-Dos Bocas Stream at night on 10 May 2008 ( Figure 4D); eight masses with 20-72 eggs (x = 41.3, N = 8) were recorded between 13 April and 16 May 2008 on the underside of leaves 0.3-6 m above a stream. Eggs clutches were guarded by calling males on the underside of leaves. We analyzed 13 calls from a single male (SVL = 22.57 mm; not collected) recorded on 13 April 2008 at the Duchas stream, ca. 3 m above water. Calls consist of a single note with an average dominant frequency of 6393.7 kHz ±217.2 Hz, fundamental frequency 3196.85 KHz ±108.60 Hz, and average call duration 0.0517s ±0.02s ( Figure 6). Cisneros-Heredia and McDiarmid (2007) suggested that several species maybe under the name H. valerioi.
Sachatamia albomaculata (Figure 4) was reported for the first time for Ecuador by Guayasamin et al. (2006), thus extending its distribution range from humid lowlands and premontane slopes from north-central Honduras to northwestern Ecuador. In April 2007 two amplectant specimens were recorded, but not collected, by G. Jongsma and R. Hedley, near the Piscinas Trail ( Figure 1). The Bilsa Biological Station is the southernmost locality in the distributional range of S. albomaculata, extending the known geographic range by 66.8 km from its closest northern locality (Reserva Biológica Canandé; Guayasamín et al. 2006; Figure 7). At BBS, S. albomaculata and Hyalinobatrachium valerioi were found in sympatry with Cochranella mache, Teratohyla pulverata and Espadarana prosoblepon.

Comments on unconfirmed species
Ecnomiohyla sp. (cf. phantasmagoria): A juvenile (uncollected; Figure 10) was found on a leaf close to the ground at a stream next to the Duchas stream at night on 30 January 2008. This frog had a dorsum mottled brown, black, and dark green; areolated belly, chest, and throat white with black blotches; ventral surfaces of limbs bright yellow with black blotches; large digital discs and extensive webbing; and scalloped dermal flaps along the outer limb margins. Ecnomiohyla phantasmagoria is known to occur at two localities separated by 1,000 km: Río Cauca, near the border of the departments of Antioquia and Bolivar in north-western Colombia; and, extreme north-western province of Esmeraldas, Ecuador, at 500 m (Frost 2008;Jungfer and Renjifo 2008). We revised photographs of the specimen reported as E. phantasmagoria by Jungfer and Renjifo (2008) deposited at the National History Museum of Vienna (NHMW 32168). It coincides with the characteristics described for the species and is morphologically similar to the juvenile from Bilsa, although differ in the ventral color pattern and presence of the supratympanic fold.
Sibon sp. (Figure 9) is characterized by: (1) mediumsized body (450-550 mm); (2) 15 row scales, (3) body laterally compressed; (4) neck pronounced; (5) seven supralabials, commonly 5-7 in contact with the ocular orbit; (6) dark red eyes, vertical elliptic pupils; (7) dorsal scales smooth, without apical pits; (8) (Savage and McDiarmid 1992;Uetz 1995Uetz -2008. The dorsal color pattern, vertebral scales slightly enlarged than other dorsal scales, and 7 supralabial scales immediately differentiate Sibon sp. from Sibon nebulata, Dipsas andiana and D. gracilis at Bilsa. Four specimens (DHMECN 3632,3649,3785,3786) are assigned to Colostethus (Grant et al. 2006) and seem to correspond to a putatively undescribed species characterized by: (1) finger III not swollen in adult males; (2) dorsolateral stripe absent; (3) cream oblique lateral stripe present, constricted, discontinued, fading to gray in inguinal region, but continuing; (4) ventral surface of body immaculate cream to white in females; throat and chest marbling or blotched as brown-dark grey in adult males, belly uniform cream; (5) dorsum reddish brown in life; (6) bright yellow axillary, inguinal and shank flash marks. Colostethus panamensis is the only species in the Choco Region that has yellow bright marks in the armpit, groin and shanks (Grant 2004). Colostethus sp. ( Figure  10) differs from C. panamensis in being the oblique pale stripe extending from the groin to eye (extending only midway to eye in C. panamensis), by has pale brown with scattered diffuse cream flecks in the flanks, between the ventrolateral and oblique lateral stripes, whereas that region is solid dark brown in C. panamensis and adult  (Grant 2004). Relative tympanic size is also diagnostic between both species: conspicuous and large in Colosthetus sp., while inconspicuous and small in C. panamensis. Other sympatric dendrobatids at Bilsa are Oophaga sylvatica, Epipedobates boulengeri and Hyloxalus awa.
Pristimantis sp. (Figure 10) is apparently the same undescribed species cited as Eleutherodactylus sp. by Cisneros-Heredia (2006a) from Parque Nacional Machalilla, in the Province of Manabí. Two specimens were captured by C. Aulestia on the night of 16 Novembrer 2006 and by C. Paucar on 25 April 2008, both near to the Duchas stream. These specimens had granular ventral skin and white marks on the dorsal surfaces of the body and legs.
A specimen (DHMECN-HMOA 1360) assigned to the genus Euspondylus was found dead on the road that leads from the scientific station to la Yecita by L. M. Krogstad on 9 November 2007 ( Figure 11). The specimen is characterized by: (1) Head slightly longer than wide; (2) no granular dorsal scales; (3) nasal scales separated from each other by the rostral and frontonasal scales; (4) presence of ear opening with recessed tympani; (5) moveable eyelids; (6) limbs each with five well developed, clawed digits; (7) interparietal scale larger than the length of parietal scales, and together, their posterior border not forming an aligned transverse straight suture across the back of the head; (8) no granular scales on the neck; (9) lateral scales reduced in size; (10) dorsum brown with black marks through the body; (11) ventral surfaces with black scales bordered with bright yellow. Only Euspondylus guentheri and Euspondylus maculatus are currently reported for Ecuador, but both occur on the eastern flanks and tropical lowland forest of Ecuador (Coloma et al. 2000(Coloma et al. -2009. We have photographs of an unidentified caecilian, a lizard of the genus Ptychoglossus, and two Colubrid snakes that could not be assigned to any known species from the western Ecuador ( Figure 11).
The documented herpetofauna of Bilsa Biological Station represents the 8 % and 18 % of the total number of amphibians and reptiles recorded for Ecuador, respectively (Coloma et al. 2000(Coloma et al. -2009Torres-Carvajal 2000-2009Coloma 2005Coloma -2009. Bilsa Biological Station is the second richest area in the Pacific slopes of Ecuador, surpassed only by the Centro Científico Río Palenque, west-central Ecuador (Miyata in litt.), where 145 species were reported. Since most of Palenque's forest have been lost due to fragmentation and uncontrolled logging (Wilson 1991), the Mache-Chindul Mountains are the last remnants of tropical-subtropical forests in the northwestern Ecuador, identified as a Priority Area of Conservation (Cuesta-Camacho et al. 2007).
Amphibian and reptile communities are known to be sensitive to environmental changes and are easily affected by fragmentation, logging and changes in microclimatic variables through a disturbed gradient in the habitat structure (Pearman 1997;Alcala et al. 2004;Urbina-Cardona et al. 2006). After 149 hours/person sampling with VES, a total of 668 individuals of 58 species were captured (29 amphibian and 29 reptiles). In forested areas we captured 196 specimens from 13 amphibians and 24 reptiles. The most frequent amphibian species were Pristimantis achatinus (30 %), Oophaga sylvatica (28%), Pristimantis latidiscus (20 %) and Rhinella margaritifera (7 %). For reptiles, the most frequent species were Alopoglossus festae (21 %), Lepidoblepharis ruthveni (12 %), Anolis gracilipes, Oxybelis brevirostris and Enyalioides heterolepis, with 8 specimens each one. In forested areas with streams/waterfalls we captured 463 specimens of 19 amphibians and 8 reptiles. In contrast with the forested areas, the most frequent amphibians were Espadarana prosoblepon (29 %), Hypsiboas picturatus (28 %), Cochranella mache (11 %) and Pristimantis achatinus (10 %). We captured only 9 individuals corresponding to the lizards Anolis lynchi (2), Basiliscus galeritus, Enyalioides heterolepis, Echinosaura horrida and the snakes Dipsas gracilis, Imantodes cenchoa, Leptodeira septentrionalis ornata and Trachyboa boulengeri. In disturbed areas near to streams, swamps or roads on station, we captured 21 individuals of 10 amphibians and 9 reptiles. We found five anurans (Hypsiboas boans, Hypsiboas pellucens, Hypsiboas rosenbergi, Leptodactylus labrosus, Scinax quinquefasciatus) solely associated to this type of habitat. The lizard Anadia rhombifera was observed moving on the roof and walls of the station building, near to the kitchen. Iguana iguana was observed on the canopy of a remnant tree, near to the station entrance. We observed a reduction in the amphibian richness (41 %) through the habitat gradient. Hylid frogs were closely associated to swamps and remnants forest in disturbed areas, while most Glassfrogs, Strabomantid and Dendrobatid frogs were associated to forested areas. A similar pattern of species replacement was found at Isla Gorgona, Colombia (Urbina-Cardona and Londoño 2003).
The lowland forests of the Pacific slopes of Ecuador are home to many unique species of plants and animals (Dodson and Gentry 1978;Albuja 1999;Cisneros-Heredia 2006b;Albuja and Arcos 2007). Separated by millions of years from their relatives in the Amazon basin by the Andes, they evolved here in geographic isolation (Duellman 1979;1999;Ron 2000). Lynch and Duellman (1997) mentioned a gradual latitudinal displacement of related species of Strabomantid frogs through the Choco, with two major breaks: the first located in northern Departamento del Valle, Colombia with a considerable endemism of species, and a second major break between La Munchique in Departamento del Cauca, Colombia, and La Planada in southern Departamento de Nariño, Colombia. According to their analysis, the authors observed a disruption in the replacement of sister species like Strabomantis anatipes and S. zygodactylus -the former to the north of the Río San Juan Valley and the latter to the south of the river. Composition of Pristimantis species at Bilsa (Appendix 1) match with the southernmost Chocoan community reported by Lynch and Duellman (1997), with only Craugastor longirostris and Pristimantis achatinus distributed from Panama to western Ecuador. Low values in community similarity index between Bilsa and three other localities in northwestern Ecuador (Figures 1 and  3), reveals a replacement of species through the study area, therefore a high beta diversity in the province of Esmeraldas marked by an important component of endemic species (Appendix 1). Some differences may be explained by different sampling efforts between the studies compared here. However, 18 % of the species at Ortega-Andrade et al. | Herpetofauna, Bilsa Biological Station, Esmeraldas, Ecuador Bilsa are unique to lowland and foothill evergreen forest of Ecuador (0-800 m), supporting that the West Ecuadorian Area, is a biogeographic region different from the Choco and Tumbesian regions (Cisneros-Heredia 2006b). The lowlands of the Department of Nariño in southwestern Colombia have not been collected intensively (Lynch and Duellman 1997), and it is possible that some species like P. colomai, P. muricatus, Hyloxalus awa or the lizards Alopoglossus festae and Anolis peraccae could extend the limit of the West Ecuadorian Endemic Area to southwestern Colombia.
Current knowledge of Ecuadorian herpetofauna still does not allow us to develop an adequate conservation assessment for most populations of amphibians and reptiles in the country, and Bilsa is not the exception. The presence of new distributional records and new species are clear evidences that the Pacific slopes of Ecuador are understudied. Much of the herpetofauna diversity in the Pacific slopes of Ecuador is threatened by habitat loss, high deforestation rates due to unsustainable development, fragmentation, extension of the agricultural frontier, global climate change, among others. Future studies at Bilsa must include population and community ecology assessment and studies of the effects of habitat loss and fragmentation. New herpetological collections are urgently necessary to obtain specimens of species herein reported as putatively undescribed. We encourage prioritizing conservation actions on endemic and key areas, as well as increasing herpetofaunal research. We propose that the Mache-Chindul Mountains should be recognized as a Key Biodiversity Area (Gascon et al. 2007), globally important site that is large enough and sufficiently interconnected to ensure the persistence of remaining populations of endangered and endemic species in northwestern Ecuador.