Centrolene callistommum Guayasamin & Trueb, new species

(Figs. 1–6)

Holotype.— QCAZ 25832, adult male, from stream affluent of Río Bogotá (1°05'13.8" N, 78°41'25.8" W, 83 m), nearby San Francisco de Bogotá, Provincia de Esmeraldas, Ecuador; obtained on 0 1 November 2000 by Italo G. Tapia and Néstor Acosta-Buenaño.

Paratopotypes.— QCAZ 27776–8, 28558, adult females, 28555–56, 28557 (C&S), adult males, same data as holotype.

Paratypes.—QCAZ 28803, adult male, stream affluent of Río Bogotá (1°05'9.06" N, 78°41'8.7" W, 77 m) located 2 km E San Francisco de Bogotá on the San Francisco–Durango Road, Provincia de Esmeraldas, Ecuador; obtained on November 2001 by Italo G. Tapia and Néstor Acosta-Buenaño. QCAZ 27744–45, adult males, and 27768, adult female, from Río La Carolina (0°42'16.16" N, 78°12'4.14" W, 500 m), on the Ibarra– Lita Road, nearby Jijón y Caamaño, Provincia de Carchi, Ecuador; obtained on 0 2 October 2001 by Italo G. Tapia and Fernando Ayala-V.

Diagnosis.— Centrolene callistommum is easily distinguished from species in the other two centrolenid genera by having a white ventral parietal peritoneum (transparent in Hyalinobatrachium) and possessing conspicuous humeral spines in males (spines absent in Hyalinobatrachium and Cochranella). It differs from other species in the genus Centrolene by its large size (in 6 males, SVL 26.7–29.6 mm; in 5 females, SVL 30.3–31.8 mm), uniform green dorsal coloration (Table 1), and its brilliant white iris that bears black reticulations (Fig. 1). Centrolene callistommum most closely resembles C. ilex (Savage, 1967), C. prosoblepon (Boettger, 1892), and C. andinum (Rivero, 1968) . Adult males of Centrolene callistommum can be clearly differentiated from adult males of C. ilex by having conspicuous humeral spines (adult males of C. ilex with small humeral spine embedded in the arm musculature; Fig. 2). However, we are not aware of any character state that would allow differentiating females of these two species. Centrolene callistommum differs from both C. prosoblepon and C. andinum by having a uniform green dorsal coloration (dorsum green with spots in C. andinum and C. prosoblepon), slightly larger body size (in C. callistommum, SVL = 26.7–31.8 mm; in C. andinum, SVL = 21.5–27.6 mm; in C. prosoblepon, SVL = 21.7–27.2; Lynch and Duellman, 1973; Señaris and Ayarzagüena, 2005), and a white iris with black reticulations (in C. prosoblepon, iris gray or golden gray with black reticulations; in C. andinum, iris gray or dark gray with black reticulations; Lynch and Duellman, 1973; Señaris and Ayarzagüena, 2005). Furthermore, C. callistommum and C. andinum are allopatric, with the latter species being endemic of the Colombian and Venezuelan Andes.

Characterization.— (1) Humeral spines present in males; (2) liver tetralobed, covered by clear peritoneum; (3) white chromatophores (guanophores) in the anterior two thirds of the ventral parietal peritoneum; white pericardium; translucent peritoneum covering intestines, stomach, testes, gall bladder, kidneys, and urinary bladder; (4) in life, dorsum uniform yellowish green, iris brilliant white with black reticulations (Fig. 1); bones green; (5) in preservative, dorsum lavender (Fig. 3); (6) dorsal surfaces of males and females shagreen, but minute spinules evident in males (only visible under × 100 magnification); (7) snout truncate in dorsal and lateral profiles (Fig. 4); (8) tympanum small (tympanum diameter 20–30.8% eye diameter), oriented vertically, with lateral inclination; tympanic annulus visible except for dorsal border, which is covered by supratympanic fold; tympanic membrane partially pigmented, differentiated from surrounding skin; (9) no webbing between Fingers II and III, webbing between Fingers III and IV reduced, webbing between Fingers IV and V extensive (Fig. 5), webbing formula: III (1 2/3-2)–(3+-3 1/4) IV 1 2/3–(1-1 1/2) V; (10) prepollex not separated from Finger II; in males, nuptial pad Type I (Fig. 6); (11) Finger II slightly longer than Finger III (Finger III 93.3–100% length of Finger II); (12) ulnar and inner tarsal folds low; outer tarsal fold absent; (13) webbing on foot extensive (Fig. 5), webbing formula: I (0+-1)–(2-2+) II (0+-1)–(2-2+) III (0+-1)– 2– IV (2-2 1/3)–(1-1+) V; (14) skin below vent with paired enlarged tubercles (Fig. 6); (15) disc of Finger IV of moderate size, about 28.6– 34.1% eye diameter; (16) vomerine teeth present, each vomer with 2–7 teeth; (17) males call from upper sides of leaves; fighting behavior unknown; females deposit eggs on upper sides of leaves; (18) in males, SVL 26.7–29.6 mm (= 27.9 ± 0.999; n = 6); in females, SVL 30.3–31.8 mm (= 31.2 ± 0.581; n = 5).

continued.

Description of holotype.—Adult male, SVL 29.6 mm. Head as wide as long; head length 33% SVL; snout truncate in dorsal and lateral profiles; canthus rostralis indistinct, straight; loreal region slightly concave; lips slightly flared; nostril protuberant, closer to tip of snout than to eye, directed dorsolaterally; internarial area barely depressed. Eye large, directed anterolaterally at an angle of 45°; transverse diameter of disc of Finger IV 46 % eye diameter. Supratympanic fold conspicuous, obscuring dorsal portion of tympanic annulus; tympanum oriented mostly vertically, but with slight posterolateral inclination; tympanic membrane translucent, partially pigmented and differentiated from surrounding skin. Dentigerous processes of vomer low, situated transversely between choanae, each bearing two to five teeth; choanae large, longitudinally rectangular; tongue ovoid, with ventral posterior fourth not attached to mouth floor and posterior margin notched; vocal slits extending posterolaterally from the posterolateral base of tongue to angle of jaws.

Humeral spine present and visible externally (Fig. 2); low ulnar fold evident; relative lengths of fingers: IV> V> II ≈ III; webbing between Fingers II and III absent, webbing formula for outer fingers: III 2–3 1/4 IV 2 – –1+ V; discs expanded, nearly round; disc pads triangular; subarticular tubercles small, round, simple; supernumerary tubercles absent; palmar tubercle elliptical, simple; nuptial pad large (Type I of Flores, 1985), ovoid, granular, extending from ventrolateral base to dorsal surface of Finger II, covering the proximal half of Finger II.

Length of tibia 54% SVL; low inner tarsal fold evident; outer tarsal fold absent; feet about fully webbed; webbing formula of foot: I 1–2 – II 0+–2 III 1 – –2– IV 2–1 V; discs on toes round; disc on Toe IV narrower that disc on Finger IV; disc pads triangular; inner metatarsal tubercle large, ovoid; outer metatarsal tubercle round, barely evident; subarticular tubercles small, round; supernumerary tubercles absent.

Skin on dorsal surfaces of head, body, and lateral surface of head and flanks shagreen with numerous minute spinules; throat smooth; belly and lower flanks areolate; cloacal opening directed posteriorly at upper level of thighs, bordered laterally by fleshy, tuberculate, ∩− shaped fold; cloacal tubercles small, fleshy, located immediately posterior to cloacal slit. Pair of large subcloacal tubercles evident in ventral aspect (Fig. 6 B).

Color in life. —Based on the color slides shown in Figure 1. Dorsum uniform yellowish green; upper lip with whitish-cream coloration; iris brilliant white with black reticulations; flanks white; parietal peritoneum white, covering anterior two thirds of abdomen (heart not visible); bones green; humeral spine bluish green.

Color in preservative.— Dorsum of head, body, and limbs uniform lavender (Fig. 3); upper lip cream; iris white with dark lavender reticulations; nuptial pad on Finger II cream; dorsally, Fingers II and III and Toes I– III unpigmented; venter cream.

Measurements.—The morphometric data for the holotype (male, QCAZ 25832) are: SVL = 29.6; tibia length = 16.1; foot length = 12.9; head length = 9.7; head width = 9.8; interorbital distance = 3.1; upper eyelid width = 2.8; internarial distance = 2.2; eye-to-nostril distance = 2.2; snout-eye distance = 3.9; eye diameter = 4.1; tympanum diameter = 0.9; eye-tympanum distance = 2.1; radioulna length = 6.4; hand length = 8.8; Finger-II length = 5.7; Finger-III length = 5.4; and disc of Finger IV = 1.9. Measurements of the paratypes are presented in Table 2.

Va r ia ti o n.—Females differ from the holotype and other males by lacking spinules on the dorsum and a humeral spine on the arm. One female (QCAZ 27778) has numerous small, dark spots on the dorsum.

Etymology.—The specific name callistommum is derived from the Greek kallistos–, meaning "most beautiful" and omma, meaning "eye."

Distribution and ecology.— Centrolene callistommum is known from tributaries of the Río Bogotá (1°05'13.8" N, 78°41'25.8" W, 83 m; 1°05'9.06" N, 78°41'8.7" W, 77 m), Provincia de Esmeraldas, and from the Río La Carolina (0°42'16.16" N, 78°12'4.14" W, 500 m), on the Ibarra– Lita Road, nearby Jijón y Caamaño, Provincia de Carchi, Ecuador (Fig. 7). These localities are in the Evergreen Lowland Forest (Bosque Siempreverde de Tierras Bajas) formation as defined by Cerón et al. (1999) in northwestern Ecuador. Centrolene callistommum is active during the night and has been found on leaves along streams. Males call from the upper sides of leaves, and females deposit pigmented eggs on the upper sides of leaves (QCAZ database).

Relationships.—In general morphology, Centrolene callistommum resembles C. ilex; however, there are marked differences between the humeral spines in the two species (Fig. 2). Molecular data (JMG, unpubl.) indicate that C. callistommum is most closely related to Centrolene prosoblepon and C. andinum .