First record of Corallus blombergi ( Rendahl & Vestergren , 1941 ) ( Serpentes , Boidae ) from Colombia

We report the first record in Colombia of Blomberg’s Tree Boa, Corallus blombergi (Rendahl & Vestergren, 1941), based on 2 specimens from Tumaco municipality, department of Nariño, Colombia. The present record extends this species’ documented distribution northwest by 55 km from its nearest previously known Ecuadorian occurrence and increases the number of Corallus species in Colombia to 5. In addition to summarizing its distribution, we present a brief comparison with the distribution of C. annulatus (Cope, 1876), the species most similar to C. blombergi.

Four species of Corallus have been reported in Colombia-Corallus annulatus (Cope, 1876), C. batesii (Gray, 1860), C. hortulanus (Linnaeus, 1758), and C. ruschenbergerii (Cope, 1876)-in lowland forests and scrubland, at elevations from sea level to elevations of about 1000 m (Henderson et al. 2009).However, Henderson et al. (2001) suggested that C. blombergi (Rendahl & Vesterfren, 1941) is likely in southwestern Colombia, based on an unexamined specimen from Tumaco, department of Nariño, which was deposited at the Instituto de Ciencias Naturales, Universidad Nacional de Colombia (ICN-R 6680).Although they thought that this specimen was most likely C. blombergi, they had not examined it and were reluctant to assign it to this species.
Corallus blombergi was considered to be endemic to Ecuador.This is an uncommon boid snake described by Rendahl and Vestergren (1941) as a subspecies of C. annulatus.The subspecies was described based on a single specimen from Río Zamora, eastern Ecuador.Rendahl and Vestergren (1941) diagnosed the 3 subspecies, C. a. annulatus, C. a. blombergi, and C. a. colombianus, by the lepidosis of snout, the presence or absence of a nasal-infraloreal contact, and the number of supraloreals present.However, Peters (1957) suggested that these characters were of doubtful validity.Later, Orcés and Matheus (1988) and Henderson et al. (2001) concluded that none of these characters have a diagnostic value because of their ambiguity and variability.Henderson et al. (2001) elevated C. blombergi to full species, based on morphological characters and geographic distribution.
Here, we confirm the presence of C. blombergi in southwestern Colombia, summarize its distribution, and provide morphological differences to the most closely related species, C. annulatus.

Methods
A field survey was carried out in Nariño, Colombia by means of active searching method.The specimens collected were euthanized, fixed in 10% formalin and preserved in 70% ethanol.They were deposited at the reptile collection of the Instituto de Ciencias Naturales, Universidad Nacional de Colombia, Bogotá, Colombia (ICN-R).The collecting activities were legally permitted under Permiso Marco de Recolección de Especímenes Number 0255, Universidad Nacional de Colombia-Ministerio del Medio Ambiente y Desarrollo Sostenible.

Record of C. annulatus.
Colombia, Nariño, Salahonda, Francisco Pizarro (02°02.46′N, 078°39.22′W, 11 m above sea level), 1 March 2016, Guido F. Medina collector, 1 individual (ICN-R 12701).This is a similar species, collected in a nearby locality, in a straight-line distance of 55 km from the collecting site of the new record of C. blombergi.
Identification.Henderson et al. (2001) diagnosed C. blombergi by the combination of the following characters: nasal contact usually absent, 76-86 subcaudal scales, 50-55 dorsal scale rows, and 251-269 ventral scales; dorsal ground color milk-chocolate brown, dorsal blotches usually 7-8 scales wide at midbody, central area of dorsal blotches paler than dorsal ground color (Fig. 2), and 6 infraloreals plus loreals (Fig. 3).The specimen referenced by Henderson et al. 2001 (ICN-R 6680) and our specimen (ICN-R 12654) agree with the diagnosis of C. blombergi by Henderson et al. (2001) in the absence of nasal contact, presence of 6 infraloreals plus loreals, dorsal blotches 8 scales wide at midbody, 254-256 ventrals, and milk-chocolate brown dorsal ground color (Table 1, Figs 2, 3).Taking into account the diagnosis and comparisons provided by Henderson et al. (2001), we found that in the specimens examined of C. blombergi, the number of subcaudal and dorsal scale rows are differing by 1-4 scales (Table 1).This slight variation could be explained by the small sample size reported by Henderson et al. (2001), meaning that the actual scale ranges are probably underestimated.The identity of both specimens was confirmed by Henderson (pers. comm. 2017).Henderson et al. (2001) distinguished C. annulatus from C. blombergi mainly because the former has a red-brown dorsal ground color, the dorsal blotches 9-10 scales wide at midbody, the central areas of dorsal blotches essentially the same shade as the dorsal ground color, and 8-9 loreals plus infraloreals.Specimen ICN 12701 has 9 loreals plus infraloreals, dorsal blotches 11 scales wide at midbody and the color pattern of the dorsal blotches as expected.Thus, we identified our specimen as C. annulatus (Table 1, Figs 2, 3).This identity was also confirmed by Henderson (pers. comm. 2017)

Discussion
Corallus blombergi was previously believed endemic to western Ecuador, although it was suspected to occur in Colombia.Herein, we provide the first definite record of this species in Colombia, extending its geographic range by about 55 km northwest (Henderson 1993).This is a very rare snake that inhabits the understory and canopy of tropical rainforest and tropical moist coastal forest, but it is apparently tolerant to disturbance since it also inhabits disturbed or modified habitats (Henderson et al. 2001, Valencia et al. 2008, MECN 2010).
This species is being severely affected by habitat loss, its populations are severely fragmented, and its area of occupancy is small; for these reasons C. blombergi has been categorized as Endangered by the IUCN (Cisneros-Heredia 2016).The previously known Extent of Occurrence (EOO) of this species was less than 4000 km 2 (Cisneros-Heredia 2016), but with the Colombian records added, its EOO increases to 5400 km 2 , according to an approximation made with GeoCAT (Bachman et al. 2011).This change in EOO (> 5000 km 2 ) and the possibility of increasing the number of locations (> 5) imply consider a change to Vulnerable using the criteria B1ab(iii,iv,v).
Hence, the importance of new records in Colombia, which open the possibility that this species has a slightly greater distribution range that possibly includes protected areas in Colombia.However, it seems likely that records in Tumaco are at the northernmost limit of the species, because C. annulatus was recorded only a few kilometers to the north (Fig. 1), showing a parapatric distribution or an area of contact between these sister species.This is an important topic for biogeographical studies of the genus.
We attribute the presence of C. blombergi in Colombia partly to the continuity of ecosystems on the Southwest Pacific Plains acting as a corridor for rainforests; however, the presence of this species is mainly due to the biogeography of the rainforests of the Ecuadorian western region (Colston et al. 2013).With increased human population and intrusion into the Chocó Biogeographic Region, threats to this species, such as agriculture, livestock farming, logging, urban growth, and illegal mining, are increasing.

Figure 1 .
Figure 1.Distribution map of Corallus blombergi and C. annulatus.The yellow squares correspond to the records of C. annulatus (Appendix 1).The green dots indicate previous records for C. blombergi in Ecuador (Appendix 1).The red stars indicate the new localities where the specimens of C. blombergi were found at Tumaco municipality, department of Nariño, Colombia.