Descriptions of New Hylid Frogs From Mexico and Central America

by William Edward Duellman

Plate 19

Holotype.—Adult male, UMMZ 94428, from Barrejonel (19 kilometers west of Chicomuselo), Chiapas, México, elevation 1000 meters, obtained on June 12, 1941, by Eizi Matuda.

Paratypes.—Two subadult males, KU 58873 from Parajé El Triunfo, north of Mapastepec, Chiapas, México, elevation 2050 meters, obtained on May 12, 1960, by Miguel Alvarez del Toro, and UIMNH 40837 from Cerro Azul Oaxaca, México, obtained on March 7, 1956, by Thomas MacDougall.

Diagnosis.—A Plectrohyla having a bifid prepollex, bold mottling on flanks and ventral surfaces of shanks, and vertical dark bars on anterior and posterior surfaces of thighs, and lacking vocal slits and outer tarsal fold.

Description of holotype.—Adult male having a snout-vent length of 63.8 mm.; tibia length 34.9 mm., 54.7 per cent of snout-vent length; foot length (measured from proximal edge of inner metatarsal tubercle to tip of longest toe) 31.1 mm., 48.7 per cent of snout-vent length; head length 19.7 mm., 30.9 per cent of snout-vent length; head width 22.6 mm., 35.4 per cent of snout-vent length. Snout short, distance from level of anterior edge of orbit to tip of snout 70.6 per cent of length of eye; snout in lateral profile angular, sloping abruptly from nostrils to jaw, in dorsal profile bluntly rounded, lacking rostral keel; canthal ridge thickened; loreal region deeply concave; lips thick, barely flared. Nostrils small, barely protuberant, directed anterolaterally, situated about two-thirds distance from eye to tip of snout; internarial distance 5.6 mm. internarial area barely depressed near convergence of canthal ridges; top of head flat; interorbital distance 6.4 mm., 28.3 per cent of head width; diameter of eye 6.8 mm.; width of eyelid 5.5 mm., 24.3 per cent of head width. Heavy dermal fold extending posteriorly from posterior edge of orbit, covering upper edge of tympanum; two thinner folds extending ventrally from longitudinal heavy fold covering posterior edge of tympanum; anterior and ventral edges of tympanum distinct; length of tympanum 2.9 mm., 42.6 per cent of diameter of eye.

Fig. 2. Palmar view of prepollical spine of right hand of
Plectrohyla hartwegi (UMMZ 94428). × 5.]

Axillary membrane absent; arms robust, forearm not noticeably heavier than upper arm; distinct transverse fold on wrist. Fingers long, moderately slender; length of fingers from shortest to longest, 1-2-4-3; discs moderately large, that on third finger larger than tympanum; webbing vestigial; subarticular tubercles small, conical; terminal tubercle on fourth finger somewhat flattened; supernumerary tubercles small, in one row on proximal segment of fourth finger and in two rows on proximal segments of other fingers; prepollex greatly enlarged, barely bifurcate; spines not protruding through skin; distal spine much longer than proximal one (Fig. 2). Heels overlap by about one-third length of shank when hind limbs adpressed; tibiotarsal articulation extends slightly beyond snout; heavy transverse dermal fold on heel; inner tarsal fold heavy, extending full length of tarsus; outer tarsal fold absent; inner metatarsal tubercle high, elliptical, visible from above, outer metatarsal tubercle absent. Toes long, slender; length of toes from shortest to longest, 1-2-5-3-4; fifth toe nearly as long as third; discs small; subarticular tubercles small, round; supernumerary tubercles small, in single row on proximal segment of each digit; toes about three-fourths webbed; webbing extending from base of disc of first toe to base of penultimate phalanx of third, from base of disc of third to base of penultimate phalanx of fourth to base of disc of fifth toe.

Anal opening directed posteroventrally at level of mid-thigh; anal sheath long with membranous connection to posterior surfaces of thighs. Skin on dorsal surfaces finely tuberculate; that on throat, chest, belly, and ventral surfaces of thighs granular, that on ventral surfaces of arms and shanks smooth. Tongue nearly round, free posteriorly for about one-fourth its length, barely notched behind. Upper jaw shallowly notched medially. Maxillary-premaxillary teeth 38-35; prevomerine teeth 5-5, situated on small elliptical elevations between quadrangular choanae; vocal slits absent.

Color (in preservative): uniform dull brown above and creamy yellow below; flanks brown with creamy yellow mottling and dark brown spots in groin; anterior surfaces of thighs creamy yellow with two broad, vertical, dark brown bars proximally and two narrower, dull brown bars distally; posterior surfaces of thighs brown with dark brown vertical bars, interspaces cream-colored or brown. Ventral surfaces of shanks creamy yellow with bold brown reticulations.