Atelopus orcesi, Coloma, Luis A., Duellman, William E., C, Ana Almendáriz, Ron, Santiago R., Terán-Valdez, Andrea & Guayasamin, Juan M., 2010

Coloma, Luis A., Duellman, William E., C, Ana Almendáriz, Ron, Santiago R., Terán-Valdez, Andrea & Guayasamin, Juan M., 2010, Five new (extinct?) species of Atelopus (Anura: Bufonidae) from Andean Colombia, Ecuador, and Peru, Zootaxa 2574, pp. 1-54 : 16-20

Atelopus orcesi sp. nov.

Holotype. MHNG 2684.75, adult gravid female, from La Alegría-Sibundoy (0˚ 34' N, 77˚ 31' W; 2400 m), Provincia de Sucumbíos, Ecuador, collected in May 1988, by Ana María Velasco.

Paratype. MHNG 2559.67, adult male with same data as holotype.

Diagnosis. (1) A medium-sized species with SVL in adult male 29.4 mm and in adult female 42.1 mm; (2) hind limbs short, tibia length/SVL 0.354–0.415; (3) phalangeal formula of hand 2-2-3-3 (inferred), basal webbing absent; (4) foot webbing formula I (0-0+)—(½-1) II (0+)—(1-) III (½-1-)—(½) IV (½)—(0—½) V; (5) snout acuminate, protruding beyond lower jaw; (6) tympanic membrane absent; (7) dorsal surfaces of body smooth, and warty on limbs; (8) row of yellow creamy warts on dorsolateral body of male, flanks with few, scattered, minute spiculae on female; (9) vertebral neural processes inconspicuous; (10) dorsum light to dark brown (in preservative), bearing a rudimentary X-shaped mark anteriorly and scattered small marks posteriorly; (11) minute gray stippling absent on dorsum of body, but minute white stippling present; (12) venter cream (in preservative) with a brown mark on gular-chest region; (13) gular region without warts, spiculae or coni.

Atelopus orcesi sp. nov. is distinct from most species of Atelopus by the combination of two features, i.e., bearing an X-shaped mark on anterior dorsum and by male having a conspicuous dorsolateral row of warts on the body. Only A. laetissimus Ruiz-Carranza, Ardila-Robayo , and Hernández-Camacho, A. mucubajiensis Rivero , A. nahumae Ruiz-Carranza, Ardila-Robayo , and Hernández-Camacho, A. pinangoi Rivero , and A. sanjosei Rivero and Serna , share these two features. Atelopus cruciger Lichtenstein and Martens and A. walkeri Rivero also have these features, but females of these species have a conspicuous dorsolateral row of warts on the body (absent in female A. orcesi ).

Atelopus orcesi is mostly similar to two specimens ( Atelopus sp. 16; Rueda-Almonacid 2005a) from Departamentos del Chocó and Valle from western Colombia. Although they are geographically separated and on opposite sides of the Andes, and they also differ by female of A. orcesi having a brown band on flank, the possibility that they are conspecific remains to be further investigated with a larger sample size. The morphological character that differentiates them might be polymorphic. Atelopus orcesi also is similar to A. nepiozomus Peters from Provincia Morona-Santiago in southeastern Ecuador. Both have a similar ventral color pattern. Atelopus orcesi is larger (female holotype SVL: A. orcesi = 42.1 vs A. nepiozomus = 32.4) and lacks warts on dorsum (many low, rounded warts and pustules, which may be spiculate in A. nepiozomus ).

Atelopus orcesi differs from Atelopus laetissimus , A. mucubajiensis , A. nahumae , and A. pinangoi by the contrasting color of the row of warts (not contrasting color in A. laetissimus , A. mucubajiensis , A. nahumae , and A. pinangoi ), and by the female having a pale brown band on the flank (band on flank absent in A. laetissimus , A. mucubajiensis , and A. pinangoi ). Furthermore, A. orcesi is geographically distant and geographically isolated from A. laetissimus and A. nahumae in the Sierra Nevada de Santa Marta in Colombia, and from A. mucubajiensis and A. pinangoi in the Sierra de Santo Domingo in the Cordillera de Mérida of the Venezuelan Andes. Atelopus orcesi differs from the smaller A. sanjosei (female SVL A. orcesi = 42.1 vs females SVL A. sanjosei = 31.5–32.7 mm, n = 2) (from the eastern versant of Cordillera Central in Departamento Antioquia, Colombia) by female of A. orcesi lacking the dorsolateral row of warts (present in female A. sanjosei ) and by having a brown mark on gular-chest region (absent in A. sanjosei ).

Description of holotype. ( Figs. 7 A, 8A, 8C, 8D, virtual animation). Female. Head about as long as wide, HLSQ and HDWD less than one third SVL (HLSQ/SVL = 0.263, HDWD/SVL = 0.256); snout acuminate, its margin triangle-shaped with a round anterior vertex in dorsal view; profile of tip of snout in lateral view nearly straight and protuberant to the anterior margin of jaw; no swollen gland on tip of snout; nostrils slightly protuberant, directed laterally, situated posterior to level of apex of lower jaw; canthus rostralis distinct, weakly concave from eye to nostril; loreal region concave; lips slightly flared; interorbital and occipital regions flat, smooth; eyelid flared without tubercles; postorbital crest slightly raised, not glandular; low pretympanic and post-tympanic areas warty; tympanic membrane and tympanic annulus absent; temporal area smooth; choanae small, rounded, widely separated (29 % of HW); tongue about twice as long as wide, its posterior half not attached to floor of mouth.

Forearm relatively short (RDUL/SVL = 0.264); palmar tubercle round; thenar tubercle nearly indistinct, supernumerary palmar and subarticular tubercles absent; digital tips with round pads; thumb relatively long (THBL/HAND = 0.615), apparently having two phalanges; webbing on hands absent, fingers lacking lateral fringes; relative length of fingers II<III=V<IV. Tibia relatively short (TIBL/SVL = 0.354); fold on distal half of inner edge of tarsus absent; inner metatarsal tubercle oval, distinct; outer metatarsal tubercle conical, low raised, about one third length of inner metatarsal tubercle; supernumerary plantar and subarticular tubercles absent; digital pads distinct; webbing formula of foot I(0+)—(1-) II(0+)—(1-) III(½)—(½) IV(½)—(½) V; relative length of toes I<II<III=V<IV.

Dorsal surfaces of body smooth; dorsal surfaces of limbs bearing small warts, except on hands and feet; warts present on temporal region and flanks with minute, scattered spiculae; anterior and upper surfaces of arms bearing spiculae; a single white, round, small, symmetrical tubercle on distal outer side of arm; throat, chest, belly, and undersides of hind limbs nearly smooth; cloacal opening a tube at upper level of thighs, directed posteriorly; rugose skin with few spicuale lateral to cloacal opening, and warty area at posterior, lower thighs.

In preservative (~70 % ethanol), dorsum of head, body, loreal and temporal regions mostly pale brown with a rudimentary (fragmented) X-shaped mark on head and suprascapular region, dorsum of body bearing three small dark brown marks; pale brown, oblique lateral band (bordered by a dark brown line) from temporal to inguinal regions, upper margin of band nearly straight and lower margin irregular; dorsal and ventral surfaces of limbs dark brown, with scattered darker or paler marks; minute white stippling present (gray stippling absent) on dorsum of body (viewed at maximum magnification with a dissecting microscope); tips of spiculae white; throat cream with a large brown mark extending to chest; belly, ventral surfaces of limbs, palms, soles mostly yellowish cream, except outer marginal parts covered by brown specially at tarsus and feet; pelvic patch distally covered by black mark; proximal end of tongue lacking black pigmentation, margin of maxillae with contrasting gray stripe.

Measurements of holotype (mm): SVL 42.1, TIBL 14.9, FOOT 14.4, HLSQ 11.1, HDWD 10.8, ITNR 4.3, EYDM 3.5, EYNO 2.6, RDUL 11.1, HAND 9.6, THBL 5.9, SW 12.4.

Variation. ( Figs. 7 B, 8B, virtual animation). The male paratype has the following measurements: SVL 29.4, TIBL 12.2, FOOT 11.5, HLSQ 9.5, HDWD 9.1, ITNR 3.5, EYDM 3.1, EYNO 2.5, RDUL 8.6, HAND 7.1, THBL 4.0, SW 9.0. The male paratype resembles the holotype with the following exceptions. Sexual dimorphism is evident in that it is smaller than the female. It has vocal slits and keratinized nuptial pads on the dorsal and inner surfaces of the thumb. Forelimbs are relatively long and slender in female. A tubercle is absent on the forearm of the male, which lacks spiculae on the flanks. The male bears a dorsolateral row of conspicuous warts from the suprascapular to the inguinal regions on the body (see discussion), and has a more protuberant snout, bearing a keeled tip.

Color variation in preservative (~70 % ethanol): The dorsum is paler than in the female. The X-shaped mark on the head is more continuous, and there are more scattered marks on posterior dorsum. The marks are nearly black, and there is no defined band on the flanks.

Color in life. Unknown.

Tadpoles. Unknown.

Distribution, ecology and current population status. Atelopus orcesi is known only from the type locality on the eastern versant of Cordillera Oriental in Provincia Sucumbíos, Ecuador ( Fig. 5 ). The type locality is at about 2400 m above sea level in Montane Cloud Forest ( Valencia et al. 1999). At the type locality, annual mean temperature is 14.2 ºC and annual mean precipitation is 1199 mm ( Hijmans et al. 2005).

Atelopus orcesi is considered to be Critically Endangered (Possibly Extinct) (A2ace, IUCN Red List categories and criteria). The species is tagged as Possibly Extinct until further surveys confirm otherwise. The population probably declined dramatically (more than 80 %) in the last two decades because of climate change and the impact of pathogens, which have affected many other montane species of Atelopus . The amphibian chytrid fungus has been reported in very close proximity to the type locality near Santa Bárbara in Sucumbíos Province (= Carchi Province of Ron and Merino 2000). The risk factor of potential threat caused by the chytrid for anuran amphibian species calculated by Rödder et al. (2009: Fig. 2 C) is high at the area of its distribution.

No individuals have been reported after its discovery in May 1988, despite at least one intensive search effort of about 40 person-hours at the type locality and surroundings at elevations of 2000–2800 m above sea level, in December 2009 by Elicio Tapia and Samael Padilla of QCAZ.

Etymology. The specific name is a noun in the genitive case and it is a patronym for Gustavo Edmundo Orcés Villagómez (1903–1999), a pioneer of Ecuadorian vertebrate zoological research ( Albuja V. 2004; Adler 2007). We recognize his contributions as a mentor and professor of a generation of zoologists in Ecuador, among them, two of us (LAC and AA). The specific name also is in recognition to the Fundación Herpetológica Gustavo Orcés that through the Vivarium, initially leaded by Jean-Marc Touzet and Ana María Velasco (the latter a collector of this species), pioneered herpetological public exhibits in Ecuador since the 1980s.

Figures

FIGURE 2. — Axes PC I and PC II from Principal Components Analysis based on eight size-corrected morphological variables for populations of Atelopus ardila and A. ignescens from Colombia and Ecuador. Circles = A. ardila; X = A. ignescens.

FIGURE 5. — Map of southern Colombia and northern Ecuador showing localities of Atelopus angelito, A. ardila, A. gigas, A. orcesi, A. pastuso and a population of hypothetical hybrids between A. pastuso and A. ignescens. Symbols for A. ardila indicate one or several close localities.

FIGURE 7. — Holotype and paratype of Atelopus orcesi (MHNG 2684.75, 2559.67, respectively): (A) adult female, SVL = 42.1 mm; (B) adult male, SVL = 29.4 mm.