Rhaebo colomai Hoogmoed 1985, new combination

Rhaebo colomai (Hoogmoed, 1985) new combination

(Fig. 3)

Andinophryne colomai Hoogmoed, 1985: 264. Holotype: RMNH 21905, by original designation. Type locality “Cabeceras del Río Baboso, cerca de Lita ”, Provincia Carchi, Ecuador.

Andinophryne colomai Hoogmoed, 1989, Zoologische Verhandelingen (Leiden), 250: 1–32. Andinophryne olallai — Murillo-Pacheco, et al. 2005. Herpetological Review 36 (3): 331.

Diagnosis. A medium sized bufonid (SVL 32.6–38.4 mm in males, 54.9–59.1 mm in females) characterized by the absence of enlarged cephalic crests, yellowish-orange skin secretions (Fig. 5), elongated parotoids, extensive webbing in the toes, and flanks with areolate skin and a row of medium sized tubercles connecting the parotoid gland with the groin (Fig. 3). Testes size unknown.

Comparisons with other species. The most similar species is R. olallai. Both species differ in the pattern of tuberculation in the flanks. In R. colomai the skin on the flanks is areolate (females) to strongly areolate (males) with medium-sized tubercles, most of them arranged along an oblique lateral row from the parotoid gland to the groin (Fig. 3). In R. olallai the skin of the flanks is smooth to weakly areolate but with large, fleshy and prominent tubercles (Fig. 4). Because the amount of tuberculation is sexually dimorphic in both species, some female R. colomai may resemble the pattern seen in male R. olallai. Rhaebo atelopoides differs in having short and rounded parotoid glands (elongated and large in R. colomai).

Description. Based on three adult females and six adult males. A medium sized bufonid, SVL in males 32.6– 38.4 mm (n = 6), females 54.9 to 59.1 mm (n = 3). Morphometric measurements are shown in Table 1. Head width 88.5–95.6% of head length and 33.4–34.6% of SVL in males, 97.5–100.0% of head length and 31.1–32.6% of SVL in females; head length is 35.2–38.9% of SVL in males and 31.1–33.5% in females; head subacuminate in dorsal view, projected in profile; vertical fleshy fold at rostrum tip; distance between nostril and tip of the snout 58.8– 74.2% of the distance from the nostril to the eye in males, 23.3–31.8% in females; nostril posterior to the anterior edge of the upper lip, below canthus rostralis on slightly protruding area; nostril oval to rounded, oblique, directed laterally; area between the nostrils concave; area from tip of the snout to anterior border of eyelid flat; interorbital and occipital region flat; females with few low tubercles from the internarial region and eyelids to interglandular region; males with numerous dense tubercles and spicules extending along the entire dorsum; interorbital area much wider than the upper eyelid; internal border of eyelid delineated or not with low isolated tubercles, external border fleshy and protruding; cephalic crests absent; canthus rostralis fleshy, gently concave, not projected into the loreal region; loreal region strongly concave, in females with low tubercles extending to the area below the tympanum with four postrictal spicules and some larger tubercles and spicules reaching the junction of the forelimbs, in males numerous tubercles from the loreal region to the groin, with three to four postrictal spicules and some infraparotoidal spicules; lips not prominent, outlined dark brown in females; eyes with horizontally rounded pupil; tympanum not visible in males, completely or partially (1/2 to 3/5 of its area) visible in females, rounded to oval, 27.4 to 38.0% of eye diameter, with a fleshy and wavy fold between the posterior corner of the eyelid and the parotoid gland; parotoid glands elongated with anterior and posterior borders rounded or pointed, some pores present and undulations in the outer edge; parotoid width 25.6 to 34.6% of the length of the gland and 27.4 to 41.8% of the distance between the two parotoid glands in males, 27.5 to 62.8% and 31.3 to 61.2%, respectively, in females; dorsal skin with abundant tubercles and elevated spicules in males, smooth with small tubercles in females with micro granulations smooth in appearance, with some low tubercles on the head and dorsum; oblique lateral row of 6 to 9 tubercles isolated or fused, fleshy and prominent extending from the parotoid gland to the groin, with or without a ventrolateral line of low tubercles; ventral skin tuberculate to strongly areolate with some thin spicules at the tip of the gular region, much more evident in males.

Forelimbs slender, long, with numerous subconical tubercles and dorsal and ventral spicules (less abundant in females); length of hand is 31.8 to 35.8% of SVL in males and 36.5 to 37.1% in females; fingers basally webbed; fingers thin, long, with fleshy tip, not swollen; Finger I shorter than II; smooth palms, supernumerary tubercles inconspicuous, subarticular tubercles low, slightly visible, rounded; palmar and thenar tubercles evident, palmar tubercle rounded, 1.2 to 1.3 times larger than the elongated thenar tubercle; ulnar tubercles and ulnar fold absent; metacarpal fold absent.

Hindlimbs thin and long; in males densely tuberculate dorsally and ventrally, in females only few tubercles present dorsally; inner tarsal fold absent; outer edge of tarsus without tubercles; toes thin and long, with fleshy tip, not bulbous, with extensive membranes, all fingers distinguishable from it, webbing formula I(1.5–2)–(2– 2.5)II(1.5–2-)– 3III (2.5–3)–2.5IV in males, I1.5– 2 II(2–2-)– 3III (2.5–3)– 3IV in females; supernumerary plantar tubercles inconspicuous; subarticular tubercles ill defined; conspicuous inner metatarsal tubercle, oval, 1.5 times the size of the rounded external metatarsal tubercle.

Tongue oval, longer than wide, thin anteriorly, rounded posteriorly, attached to the mouth floor anteriorly along three fifths of its length, unnotched posteriorly; choanae round, small; males with subgular vocal sac and vocal slits; nuptial pads low, not swollen; cloacal opening directed dorsolaterally.

Distribution and ecology. Rhaebo colomai is known from three localities in the western slopes of the Andes in northern Ecuador and southern Colombia, between 1180 and 1500 m above sea level (Hoogmoed 1989; Murillo- Pacheco et al. 2005; Fig. 7). Vegetation types, according with the Ministerio de Ambiente del Ecuador (2013) classification system are Evergreen Foothill Forest of the Andean Western Cordillera (headwaters of the Baboso river and Chical); in Colombia, this species inhabits Premontane Rain Forests (sensu Holdridge 1987). In Ecuador, annual precipitation at headwaters of the Baboso river is 3394 mm and at Chical 2610 mm; mean annual temperature is 22.4 and 20.5 °C, respectively; in Colombia, annual precipitation at Río Ñambí is> 7100 mm; mean annual temperature is 19.3±1.59 °C (range 17.1–19.7 °C; Salaman 2001).

At Río Ñambí, R. colomai is restricted to old growth secondary forests. Individuals are uncommon, being observed at night perched on fallen logs, rock crevices, and on shrub or tree branches or leaves along the margins of small streams and inside the forest. Perch height of the active individuals was on average 0.87 m above ground (range 0.10–3.96 m; n = 42), with adults (mean = 1.28 m, range 0.35–3.96 m, n = 21) generally perching higher than younger individuals (mean = 0.48 m, range 0.10–1.34 m, n = 19). On individual (not collected) was observed perching on epiphytic Araceae ca. 4 m high. Amplexus and egg clutches remain unknown. One adult female (JJM 658) released a yellowish-orange secretion when it was captured.

Conservation status. Extent of occurrence is 575 km 2, including the Ecuadorian localities. However, the lack of records since 1984 at Río Baboso and Chical suggests that these populations are extinct (Coloma et al. 2010a) and therefore the current extent of occurrence might be less than 100 km 2. At both localities the forest has been logged and fragmented. At the headwaters of the Baboso River, the proportion of remaining forest, within a radius of 10 km of the collection site, is 65.3%; at Chical it is 71.8%. Chical is located within a deforested area. The Colombian locality is a natural reserve, with a forested area of about 14000 km 2 characterized by a canopy between 25 to 30 m high and a very dense understory that has a high concentration of shrubs and low diameter trees, which seems to be correlated with the selective removal of trees (Franco-Roselli et al. 1997). The area over which R. colomai has been recorded at Río Ñambí is 0.48 km 2. Because of its restricted extent of occurrence (<100 km 2), limited number of known localities (≤ 5) and increasing habitat alteration and fragmentation, we suggest that R. colomai is assigned to the Critically Endangered category (CR) under criteria B1a,b(iii).