Hyloxalus sauli (Edwards 1974)

Páez-Vacas, Mónica I., Coloma, Luis A. & Santos, Juan C., 2010, Systematics of the Hyloxalus bocagei complex (Anura: Dendrobatidae), description of two new cryptic species, and recognition of H. maculosus 2711, Zootaxa 2711, pp. 1-75 : 45-47

Hyloxalus sauli (Edwards 1974)

Colostethus sauli — Edwards 1974b:10.— Holotype: “ KU 122217, an adult male from Santa Cecilia, 340 m, Napo, Ecuador; collected by William G. Saul on 12 July 1968 ”.

Hyloxalus sauli — Grant et al. 2006:168.

Diagnosis. A species with (1) mean SVL in adult males 22.7 mm (19.7–24.9, SD = 1, n = 30), and in adult females 25.4 mm (22.2–28.7, SD = 1.4, n = 29); (2) disc of Finger IV expanded 1.5 times the width of adjacent phalange; (3) Finger II shorter than Finger III; (4) fringes present on fingers; (5) disc of Toe IV expanded 1.5 times the width of adjacent phalange; (6) fringes present on toes; (7) outer metatarsal fold present; (8) basal toe webbing, formula I(1½–2)—(2–3) II(1½–2)—(2–3½) III (2 + –3)—(3½–4 +) IV (4–4½)— (2–3) V; (9) oblique lateral stripe complete, ventrolateral stripe complete, diffuse or interrupted; (10) dorsum with three large blotches; (11) gular-chest region uniformly brown or gray in adult males, cream-colored or slightly brown with white spots in adult females; (12) venter uniformly brown or gray in adult males, cream slightly translucent or slightly flecked with brown in adult females; (13) sexual dimorphism in ventral coloration present; (14) tadpoles light brown with scattered brown blotches on tail and a large longitudinal brown mark on dorsum of tail musculature; (15) tadpole spiracular opening oriented dorsoposteriorly; (16) call is a long trill composed of single notes.

Hyloxalus sauli is similar to those species with basal toe webbing, oblique lateral stripe complete, and that lack dorsolateral stripe and pectoral marks ( H. awa Coloma , H. insulatus Duellman , H. littoralis Péfaur , H. toachi Coloma , H. vergeli Hellmich ). Hyloxalus awa has white spots over dark brown throat and chest. Hyloxalus insulatus has Finger II longer than Finger III and lacks outer metatarsal fold and metatarsal tubercle. Hyloxalus littoralis exhibits brown spots on gular-chest region, forming a subtle collar-like mark and Fingers II and III are equal in size. Hyloxalus toachi has no fringes on fingers and testes are brown. Hyloxalus vergeli is larger in size (SVL greater than 28 mm).

Description. Edwards (1974b) provided a morphological description of the species under the name of Colostethus sauli . Variation in measurements is given in Table 4 (n = 59: 30 males, 29 females). Head slightly longer than wide; snout round in dorsal view, angular in lateral view; loreal region flat; nostrils slightly protuberant; supratympanic bulge diffuse, covering upper edge of tympanum or not.

Finger II shorter than Finger III, fingers unwebbed; fringes present but discrete; terminal discs 1.5 times width of adjacent phalange; subarticular tubercles round, that of Finger II slightly oval; outer metacarpal tubercle large, round; inner metacarpal tubercle at base of thumb small, elliptical and subtly protuberant. Outer metatarsal fold present; inner sigmoid tarsal fold present on distal third of half of tarsus; outer metatarsal tubercle round; inner metatarsal tubercle smaller than outer, elliptical; protuberance between both metatarsal tubercles in 60% of examined specimens; toe webbing formula I(1½–2)—(2–3) II(1½–2)—(2– 3½) III (2 + –3)—(3½–4 +) IV (4–4½)—(2–3) V; lateral fringes present but discrete; terminal discs expanded 1.5 times width of adjacent phalange; subarticular tubercles small, round; supernumerary tubercles absent.

Skin of dorsum, limbs and venter smooth; flanks rough; tubercle posterior to mandible junction; anal sheath conspicuous. Tongue more than twice as long as wide, thinner and broader posteriorly, posterior half not attached to mouth’s floor. Testis white.

Color in preservative (~70% ethanol). Variation in color patterns is depicted on Figs. 5C – 7C. Dorsum of head and body brown, slightly reddish; a dark brown interorbital blotch, a V-shaped mark at scapular level and a blotch at posterior portion of dorsum; dark brown lateral stripe from snout to groin. Pale oblique lateral stripe conspicuous from posterior corner of eye to groin, sometimes diffuse at anterior portion; pale ventrolateral stripe complete, diffuse or interrupted. Forelimbs brown with darker transverse bars on forearm, longitudinal dark brown stripe at anterior surface of arm, cream spot at arm-body junction; dorsal surfaces of hind limbs brown with darker transverse bars (9–11 at leg and tarsus), cream spot posterior to groin; ventral surface cream in females, brown in males. Gular-chest region uniformly dark brown in males, cream or light brown in females; venter uniformly gray or brown in males, cream slightly flecked with brown in females; axillas translucent, brown band at each axilla in some male specimens. Palmar and plantar surfaces brown; toe webbing cream.

Color in life. Edwards (1974b) described color in life. An adult male and a female from PUCE’s (Pontificia Universidad Católica del Ecuador) Yasuní Research Station are depicted in Figs. 3C and 4C, respectively.

Variation. Variation in measurements is given in Table 4. Variation in color patterns is depicted on Figs. 5C – 7C. Specimens from Bloque Shiripuno (n = 2, QCAZ 8984 and 9329) and Locación Petrolera Garza 1 (n = 1, QCAZ 1435) lack ventrolateral stripe. In specimens from Puerto Bolívar (n = 3, QCAZ 28262–28263 and 28339), the ventrolateral stripe is very subtle.

Twenty juveniles (QCAZ 484, 486–487, 5318, 6879, 8082, 9404–9405, 22626, 24101–24102, 24237– 24238, 25050–25051, 25056, 25060, 25066, 28262–28263, 32476, 32478; USNM 282108–282112) with SVL of 10.3–21.4 (mean = 15.2) exhibit same coloration pattern as adults. Nonetheless, they are slightly paler and, thus, dark dorsal blotches are more contrasting. Ventrally cream-colored, some specimens translucent. Two recently metamorphosed specimens (QCAZ 5313 and 25051) have SVL of 12.1 and 10.49 respectively.

Tadpole. Edwards (1974b) described tadpoles in Stages 27–36. Duellman (1978) described tadpoles at Stage 36. Tadpoles of Hyloxalus sauli are similar to H. bocagei tadpoles. Nevertheless, the latter are round, their snout is more elongated, tail musculature is slender, tip of the tail is round, dorsal fin is broader at its anterior region and they are darker; the upper edge of upper jaw is straight, whereas it is subtly winding in H. sauli . Tadpoles of H. sauli are similar to H. maculosus tadpoles as well. However, tail in H. sauli is more heavily pigmented, spiracular opening is directed dorsoposteriorly (laterally in H. maculosus ) and the upper edge of the upper jaw is slightly winding (straight in H. maculosus ).

Comments. Edwards’ (1974b) description is appropriate with the exceptions noticed by Coloma (1995). Additionally, Finger II is shorter than Finger III and females might exhibit brown spots on venter, whereas venter in males lacks spots. Edwards (1974b) also remarks on the absence of ventrolateral stripe. Nonetheless, 88% of examined specimens exhibit ventrolateral stripe, complete, diffuse, or interrupted. Further information is included under Phylogeny and Chronogram and Ancestral Area Reconstruction sections ( Tables 2 and 3; Fig. 1).