Rhaebo olallai ( Hoogmoed, 1985 ) Hoogmoed, 1985

Ron, Santiago R., Mueses-Cisneros, Jonh Jairo, Gutiérrez-Cárdenas, Paul David Alfonso, Rojas-Rivera, Alejandra, Lynch, Ryan L., Duarte Rocha, Carlos F. & Galarza, Gabriela, 2015, Systematics of the endangered toad genus Andinophryne (Anura: Bufonidae): phylogenetic position and synonymy under the genus Rhaebo, Zootaxa 3947 (3), pp. 347-366 : 361-362

Rhaebo olallai ( Hoogmoed, 1985) new combination

( Fig. 4 A–E)

Andinophryne olallai Hoogmoed, 1985: 264 . Holotype: BM 1970.98, “Tandayapa”, Provincia Pichincha, Ecuador. Andinophryne olallai Hoogmoed, 1989 , Zoologische Verhandelingen (Leiden), 250: 1–32.

Andinophryne olallai Lynch et al. 2014 . Amphibian & Reptile Conservation 8: 1–7.

Diagnosis. A medium sized bufonid (SVL 43.8 mm in males, 57.0 to 60.0 mm in females) characterized by the absence of enlarged cephalic crests, yellowish-orange skin secretions ( Fig. 5 ), elongated testes, elongated parotoids, and flanks with conspicuous, fleshy and prominent tubercles ( Fig. 4 ).

Comparisons with other species. The most similar species is R. colomai . Both species differ in the pattern of tuberculation in the flanks. In R. olallai the skin on the flanks is weakly areolate but with large, fleshy and prominent tubercles; in R. colomai the skin is areolate (females) to strongly areolate (males) with medium-sized tubercles, most of them arranged along an oblique lateral row that connects the parotoid gland with the groin.

Description. Based on two adult females, one adult male (QCAZ 56576; Fig. 4 ), one subadult male (QCAZ 55561), and photographs of ~ 20 adult individuals of unknown sex. Male measurements refer to the single adult. A medium sized bufonid, SVL in males 43.9 mm, females 57.0 to 60.0 mm (n = 2); head width 105.3% of head length, 33.8% of SVL, head length is 32.2–32.8% of SVL; head acuminate in dorsal view, projected in profile; vertical fleshy fold at rostrum tip; distance between nostril and tip of the snout 64.1–70.3% of the distance from the nostril to the eye; nostril posterior to the anterior edge of the upper lip, below canthus rostralis on moderately protruding area; nostrils oval to rounded; area between the nostrils concave; area from tip of the snout to anterior border of eyelid flat to slightly convex; interorbital and occipital region flat; interorbital area much wider than the upper eyelid; internal border of eyelid not delineated with low isolated tubercles, external border fleshy and protruding; cephalic crests absent; canthus rostralis fleshy, gently concave to gently convex, not projected into the loreal region; loreal region strongly concave; lips not prominent to slightly prominent, outlined dark brown in some individuals; eyes with horizontally round pupil; tympanum not visible to barely visible in life; preserved specimen QCAZ 56576 shows a conspicuous rounded tympanum (diameter = 1.5 mm), concealed on its upper half; parotoid glands elongated with anterior and posterior borders rounded or pointed, some pores present and undulations in the outer edge; parotoid secretion yellowish-orange ( Fig. 5 B); two adult females lack dorsal tubercles except for few indistinct flat tubercles in sacral region ( Fig. 4 A); male QCAZ 56576 has numerous tubercles and spicules over the entire dorsum ( Fig. 4 C); a majority of individuals of undetermined sex have scant, scattered dorsal tubercles; few individuals have abundant tubercles; if present, tubercles are more abundant between the sacrum and the vent; oblique lateral row of 6 to 9 large tubercles isolated or fused, fleshy and prominent, frequently extending from the parotoid gland to the groin; large to medium sized tubercles are usually present in the flank with irregular arrangements; medium sized tubercles can reach the distal margins of the venter; ventral skin tuberculate.

Forelimbs slender, long, with or without subconical tubercles; fingers basally webbed; fingers thin, long, with fleshy tip, not swollen; Finger I shorter than II; smooth palms, supernumerary tubercles absent or scant and inconspicuous, subarticular tubercles low, slightly visible, rounded; palmar tubercles evident, rounded; thenar tubercle inconspicuous; ulnar tubercle and ulnar fold absent; metacarpal fold absent.

Hindlimbs thin and long; hindlimb tuberculation varying from abundant in dorsal and ventral faces to scant and ill-defined in the dorsal face only. Inner tarsal fold absent; outer edge of tarsus with or without tubercles; toes thin and long, with fleshy tip, not bulbous, with extensive membranes; supernumerary plantar tubercles absent; subarticular tubercles ill-defined; nearly flat inner metatarsal tubercle, oval, 3 times the size of ill-defined rounded external metatarsal tubercle.

Tongue oval, longer than wide, thin anteriorly, rounded posteriorly, attached to the mouth floor anteriorly along one half of its length, unnotched posteriorly; choanae ovoid; males with subgular vocal sac and vocal slits; nuptial pads brown and keratinous, low, not swollen; cloacal opening transversal. Testis elongated and hypertrophied, its length is 23% of SVL (QCAZ 56576); male QCAZ 55561 (SVL = 36.9 mm) is a subadult with extremely small testicles.

Distribution and ecology. Rhaebo olallai is known from two localities in the western slopes of the Andes in Northern Ecuador (elevation 1300–1500 m above sea level; Fig. 7 ). Vegetation types, according with the Ministerio de Ambiente del Ecuador 2013 classification system, are Evergreen Foothill Forest of the Andean Western Cordillera (Manduriacu) and Evergreen Low Montane Forest of the Andean Western Cordillera (Tandayapa). Annual precipitation at Tandayapa is 2731 mm and at Manduriacu 2935 mm; mean annual temperature is 17.1 and 19.6 °C, respectively. At Manduriacu all field observations took place at night in Terra Firme forest. Most adults and juveniles were observed along streams perching on vegetation up to 2 m above ground. Some individuals were observed moving actively suggesting that activity is nocturnal. Adult individuals were also observed within the forest and away from streams (distance> 50 m).

Conservation status. Assuming that populations survive at the two known localities, extent of occurrence is 1079 km 2. However, Tandayapa, the type locality, is a reserve frequently visited by naturalists and the lack of records since 1970 suggests that the population is extinct. If the single surviving population is Manduriacu, current extent of occurrence is <100 km 2. At Tandayapa, the proportion of remaining habitat, within a radius of 10 km is 74%; at Manduriacu it is 83.3%. At both localities the forest is fragmented within distances <1 km of population site. Because of its restricted extent of occurrence, limited number of known localities and increasing habitat alteration and fragmentation, we suggest that R. olallai is assigned to the Critically Endangered category (CR) under criteria B1a,b(iii).

Figures

FIGURE 4. Dorsolateral and ventral views of Rhaebo olallai and Rhaebo atelopoides. A – E: Rhaebo olallai, from Ecuador, Provincia de Imbabura, Manduriacu. F: Rhaebo atelopoides, from Colombia, type locality. A – B: adult female, SVL = 60.0 mm. C – D: adult male (QCAZ 56576), SVL = 43.9 mm. E: metamorph showing pattern of contrasting clear lines in the dorsum. F: adult male (IAvH 278), SVL = 42.3 mm. Photographs by SRR (R. olallai) and J. D. Lynch (R. atelopoides).

FIGURE 5. Skin secretions in Rhaebo. Rhaebo colomai (left) and R. olallai (right). Note yellow-orange color. Photos by J. H. Mueses-Cisneros (left) and SRR (right).

FIGURE 7. Known localities for Rhaebo colomai and Rhaebo olallai. The map is based on Hoogmoed (1985, 1989) and localities reported herein.