The Spotted Nurse Frog Allobates algorei (Barrio-Amorós & Santos, 2009)

was previously known from three sites in Táchira state in Venezuela (400–1000 m a.s.l.; Barrio-Amorós & Santos, 2009), near the western border with Colombia. The presence of this species in the Cordillera Oriental in Colombia was previously suggested but unconfirmed (Barrio- Amorós & Santos, 2009). Here, we report Allobates algorei detected in four sites along an elevational gradient at Toledo municipality in the buffer zone of Parque Nacional Natural Tamá, Norte de Santander department, Colombia (Figure 1). The specific localities were: vereda San Antonio, Margua river at 646 m a.s.l. (7°9’26,994”N, 72°13’45,446”W); 724 m a.s.l. (7°9’46,314”N, 72°15’31,71”W), and 887 m a.s.l., (7°8’38,692”N, 72°11’59,183”W); and vereda Campo Hermoso, Talco river at 1185 m a.s.l. (7°11’32,578”N, 72°18’35,256”W).

We found twelve males, two females, and five metamorphs of A. algorei during fieldwork (May and June 2010) from 10:00 to 14:00 h. Four specimens (1 adult male, and 3 metamorphs) were collected and deposited in the Museo de Ciencias Naturales of the Universidad de Pamplona, Colombia (MCNUP-H 0521 – 0524). Individuals were detected on the floor of riparian Sub-Andean forest associated with large cattle grazing areas.

For the taxonomic identification we made morphological comparisons with the original species description (Barrio- Amorós & Santos, 2009) and genetic identification by sequencing two fragments of partial genes 16s and CO1 of each specimen. We used the pairs of primers 16sar (5′ -CGC CTG TTT ATC AAA AAC AT- 3′) and 16sbr (5′ -CTC CGG TTT GAA CTC AGA TC- 3′), and the standard barcoding fragment dgLCO1490 (5′ -GGT CAA CAA ATC ATA AAG AYA TYG G) and dgHCO2198 (5′ -TAA ACT TCA GGG TGA CCA AAR AAY CA). The sequences were aligned and edited with BioEdit (Hall, 1999), including the sequences available for A. algorei (Genbank accession number: HQ 290950; voucher number: TNHCFS5551) corresponding to the type locality (Táchira: road from San Cristobal to Río Negro), and the addition of other Allobates species distributed in Colombia and Venezuela. A phylogenetic tree reconstruction was carried out with Maximum Likelihood analyses in IQ-TREE (Nguyen et al., 2015), using the TIM2+F+G4 model of evolution, and to estimate branch supports we used the ultrafast bootstrap method (Minh et al., 2013).

The pairwise genetic distances between species were calculated following the Maximum Composite Likelihood method (Tamura & Kumar, 2004) using MEGA 7.0 (Kumar et al., 2016). Genbank accession number of specimens reported in this work are: 16s (MK369818 -19) and CO1 (MK369820 -21).

Allobates algorei can be easily distinguished from similar species by the following characteristics (Barrio-Amorós & Santos, 2009): (1) fingers slightly expanded and round; (2) finger fringes absent; (3) toe webbing absent; (4) toes are slightly expanded, about 1.4 times wider than distal end of adjacent phalanx (Figure 2A); (5) metatarsal fold absent; (6) skin of dorsum from smooth to slightly granular; (7) dorsal pattern irregularly spotted; (8) lateral stripe diffuse obliquely; (9) dorsolateral stripe absent; (10) belly from spotless to pale yellow in males and immaculate in females; (11) snout is subacuminate in profile (Figure 2B); and (12) small size with adult males larger than adult females: mean SVL for adult males 20.8± 0.6 mm (n=12) and mean SVL for adult females 18.6± 0.6 mm (n=2). Males are slightly larger than reported by Barrio-Amorós & Santos (2009) (Figure 1).

Frogs of A. algorei reported in this study were often calling under rocks in the margin of the river, into the forest and near of crops indicating reproductive activity. The advertisement call (not recorded) has a pattern similar to that described by Barrio-Amorós & Santos (2009), with a single-note call at a constant rate and approximately 2–3 notes per second.

Our phylogenetic reconstruction (Figure 3) and the close genetic distance between the samples of Colombia and Venezuela (0.4 %), confirm the conspecificity of our samples with A. algorei and represents the first record of this species in Colombia, extending the species’ distribution by ca. 50 km SSW from the type locality (Río Negro, Córdoba municipality, Táchira state, Venezuela; Figure 1).

In terms of conservation status, A. algorei is included in the category of Least Concern (LC) (IUCN, 2012). However, despite this range extension, the conservation status of this species deserves to be reassessed due to: i) the individuals reported in this work are infected by Batrachochytrium dendrobatidis (Acevedo et al., 2016), and ii) a remarkable deterioration of the natural habitat in Colombia, where the representative primary forests and riparian vegetation of the region have been reduced rapidly during recent years by activities associated with the expansion of cane crops, wood extraction, and livestock. Many of these problems are present similarly in the localities reported in Venezuela, especially between the cities of San Cristóbal and El Piñal (Estado Táchira). Additional surveys investing 150 person-hours of sampling effort in the lower area of the Tamá National Natural Park (Colombia) and the buffer zone of the park did not detect other populations of this species.