Portozuelo Frog

Diagnosis A medium-sized (males to 37 mm, females to 40 mm) Atelognathus with dark spots on the dorsum.

Know only from the type locality in north-west of Santa Cruz Province, Argentina.

Description of holotype Head wider than long, about one-third body length; snout rounded in dorsal view, sharply sloping in profile, slightly overhanging lower jaw; canthus not angular, smooth; loreal region almost flat; lips moderately thick; nostrils opening anteriorly, almost terminal on snout, laterally protuberant; interocular distance equal to the upper eyelid; eye, large, diameter equal to the eye-snout distance; distance between eye and nostril about thrice distance from nostril to tip of snout; tympanum indistinct; supratympanic fold thick, extending from posterior corner of eye to insertion of forearm; choanae round; prevomerine teeth on two slightly prominent patches on median line between choanae; premaxillary and maxillary teeth evident; tongue round, not notched posteriorly, posterior one-half not adherent to floor of mouth; internal vocal sac present. Body stout; limbs moderately slender; heels slightly overlapping when hind limbs adpressed; tibio-tarsal articulation not reaching to posterior corner of eye. Tarsal fold evident; inner metatarsal tubercle paddle-shaped, pronounced; outer metatarsal tubercle smaller and conical; subarticular tubercles conical, prominent, length of digits from shortest to longest I-II-V=III-IV; toes about half-webbed with broad dermal fringe to tip; forelimb reaching groin with the tip of largest finger; length of fingers from shortest to longest II-IV=I-III; fingers with broad dermal fringe, webbing absent; subarticular tubercles prominent; surface of palm granular; inner metacarpal tubercle oval, outer rounded, enlarged; soft, unpigmented nuptial pads on pollex and second finger; skin on dorsum granular, with round, flat, longitudinally arranged glandular pustules; skin on venter smooth; skin on thigh coarsely granular; distinct discoidal fold on belly. Color in life: Dorsal surfaces of head, body and limbs yellowish with large, welldefined, symmetrical brown or black spots on the back and flanks. A dark brown transverse band across the interocular region, followed by two distinct, pale yellow rhomboidal spots on neck; pale yellow or white dots on dorsal pustules. Ventrally white, immaculate; reddish skin with white granules on thighs. Color in alcohol: Dorsum yellowish gray with black spots; venter white; red color on thighs faint. Measurements (in mm): snout-vent length 37.0; head length 11.6; head width 13.0; forelimb 21.0; hind limb 49.5; thigh 15.0; shank 15.6; foot 24.0; diameter of eye 4.2; axilla-groin distance 20.0. Variation No notable differences in proportions or coloration were observed, although females are slightly larger, on the average, than adult males. The only external character for sex recognition is the faint thumb pad of males. Larval morphology Description based on specimens at developmental stages 36 to 39 (Gosner, 1960). Medium-sized to large, total length of largest specimen of the series (stage 41) 62 mm; body length 0.4 times of total length; body shape oval, somewhat depressed, 2.3 times longer than high and 1.2 times wider than high; some specimens with a slight constriction between head and trunk; snout rounded in dorsal and lateral pro. le; eyes medium sized, dorsolaterally positioned (extraocular distance 0.62 times body width at eye level), dorsolaterally directed; eye diameter 0.2 times of head width at eye level; interorbital distance 1.3 times greater than eye diameter and 0.25 times of maximum body width; nostrils oval to subcircular, dorsal position and protuberant, raised mainly at the anterior edge; nostrils closer to eye than to tip of snout (rostronasal distance 1.3 times orbitonasal distance), openings dorsolaterally directed; internarial distance approximately 6.75 times greater than nostril diameter and 0.6 times of interorbital distance; orbitonasal line visible; gill chambers large; spiracle sinistral, conspicuous, joined to the body along its entire extent; spiracular tube and opening ventral, not visible dorsally; spiracular opening oval and smaller than tube diameter, directed posterolaterally located at 0.57 times of body length; vent tube conspicuous but short, 0.09 times of body length; vent opening dextral; caudalmusculature robust anteriorly, becoming narrower gradually toward tip of tail, not reaching the end of tail;myotomes clearly visible; height of musculature at the base of the tail approximately half maximum body height; dorsal and ventral fins well and equally developed,with slightly curved margins,matching the caudal musculature; dorsal fin arises as a low, fleshy crest at body-tail junction; ventral fin arises posterior to vent tube; tail height equal to body height; maximum tail height approximately in the middle of its length; tail axis straight (eutiural); tip of tail rounded. Oral disc anteroventral, not visible dorsally; disc small, slightly wider than interorbital distance, about 0.35 times of maximumbody width; disc with angular constrictions (emarginate); one row of marginal papillae in mental region, double row in lateral regions; with medium-sized rostral gap, about 0.6 times of oral disc width; intramarginal lateral papillae present, up to eight papillae in supra- and infra-angular regions; up to two papillae in intra-angularregions; intramarginalmental papillae absent; keratodonts numerous, well developed and keratinized; keratodont formula 2(2)/3(1); rostrodonts well developed and keratinized, wider than high, margins blunt serrated; suprarostrodont gently curved; infrarostrodont curved in a more noticeable angle. Suprarostrodont length 1.26 infrarostrodont length. Coloration in life: dorsum and body sides yellowish-brown speckled with guanophores producing a golden sheen; ventral surface golden, anteroventral region of head translucent; caudal musculature with a few dark, blurred patches on a yellowish-brown background; fins transparent; melanophore rows mark courses of blood vessels in fins and tail musculature; nostrils dark brown in median and posterior areas; iris dark, with golden flecks and reticulations; spiracular tube and vent tube translucent; keratinized structures of oral disc dark brown. In preserved specimens, the pattern of spots remains; abdomen dark; fins translucent with little pigmentation; eyes black.

VU. Vulnerable.