Gastrotheca aratia, Duellman, William E., Barley, Anthony J. & Venegas, Pablo J., 2014

Duellman, William E., Barley, Anthony J. & Venegas, Pablo J., 2014, Cryptic species diversity in marsupial frogs (Anura: Hemiphractidae: Gastrotheca) in the Andes of northern Peru, Zootaxa 3768 (2), pp. 159-177 : 170-172

Gastrotheca aratia new species

Holotype: KU 212067, adult female, from 8 km (by road) NW of Cutervo, 6˚14'00"S, 78˚51'24"W, 2560 m, Provincia Cutervo, Departamento Cajamarca, Peru, collected by J. J. Wiens on 27 February 1989.

Paratypes: KU 212055 and KU 212057, adult males, from vicinity of Cutervo, 6˚22'01"S, 78˚51'00"W, 2620 m, Provincia Cutervo, Departamento Cajamarca, Peru, collected by F. M. Cuadros and J. J Wiens on 26 February 1989; KU 212060,and KU 212062–66, adult males, collected by J. J. Wiens on 28 February 1989.

Referred specimens: KU 212056 and KU 212058–59, juveniles; MUSM 6188–72, adult males, and MUSM 6194–95, juveniles all from vicinity of Cutervo, 2620 m, Departamento Cajamarca, Peru, collected by M. E. Morrison and J. J. Wiens on 26–28 February 1989 l MCZ 5328–30, adult males, from Querocotillo, 6˚16'26"S, 79˚02'16"W, 2875 m, Provincia Cutervo, Departamento Cajamarca, Peru, collected by G. K. Noble in 1916.

Diagnosis. A moderately large species—SVL 42.8–55.7 mm (x = 48.1 ± 4.6, n = 8 males), 56.8 (n = 1 female)—with (1) tibia length 40–51% SVL, about same length as foot; (2) interorbital distance slightly less than width of upper eyelid; (3) skin on dorsum granular, smooth to slightly pustular, not co-ossified with skull, lacking transverse ridges; (4) supraciliary processes absent; (5) heel lacking calcar or tubercle; (6) tympanic annulus smooth; (7) Finger I shorter than II with discs slightly wider than digits; (8) fingers unwebbed; (9) webbing extending maximally to penultimate subarticular tubercle on Toe IV and nearly to penultimate subarticular tubercle on Toe V; (10) dorsum green or brown with darker paravertebral marks and inverted V-shaped mark posterior to sacrum; (11) head markings consisting of dark canthal stripe and pale labial stripe; (12) pale dorsolateral stripe usually present; (13) flanks and anterior and posterior surfaces of thighs lacking dark markings; (14) venter cream with dark flecks or spots; (15) brood pouch single, dorsal.

Gastrotheca aratia most closely resembles four other species in northern Peru. In contrast to the much larger G. monticola , G. aratia lacks a pale supracloacal stripe (67% of the adults examined) and black spots on the flanks and anterior and posterior surfaces of the thighs (88% of the adults examined) (Table 1; Fig. 3 ). The slightly smaller G. aguaruna— SVL 41.6–46.8 mm (x = 45.1 ± 2.17, n = 6 males), 49.4–50.8 (x = 50.1, n = 3 females)— differs by having dark marks in the groin, green vocal sac, tarsal fold extending full length of tarsus, and webbing extending only to the antepenultimate subarticular tubercle on Toe IV. Gastrotheca dysprosita differs from G. aratia by having a green dorsum with a narrow, yellow middorsal stripe and green flanks with small yellow spots; furthermore G. dysprosita lacks a dark canthal stripe and pale labial stripe and has a granular tympanic annulus. Gastrotheca lateonota differs from G. a r at i a by having a truncate snout in profile, smooth skin on the dorsum, and a nearly uniform grayish brown venter. Six other species of Gastrotheca in the Andes in northern Peru include G. peruana , G. phalarosa , and G. phelloderma , all of which have strongly pustular skin on the dorsum. In G. ossilaginis , the skin on the skull is co-ossified with the underlying dermal bones. Additionally, G. abdita , differs by having an acuminate snout in dorsal view, and G. galeata that differs from all the rest by having a spatulate labium; the latter two also produce eggs that undergo direct development.

Description of holotype. Adult female; body robust; SVL 56.8 mm; head slightly wider than long; snout rounded in dorsal view and bluntly rounded in profile, extending slightly beyond margin of lower lip; canthus rostralis acutely rounded in section; loreal region barely concave; lips rounded; top of head flat; interorbital distance 85% of width of upper eyelid; internarial area flat; nostrils not protuberant at terminus of canthus rostralis posterior to level of anterior margin of lower jaw; diameter of eye slightly greater than its distance from nostril; tympanum round, separated from eye by distance about equal to length of tympanum; tympanic annulus distinct, smooth; supratympanic fold weak, extending from posterior corner of orbit to point posterior to tympanum. Arm robust; row of ulnar tubercles absent; hand moderately large; fingers short, unwebbed; discs moderately large, rounded, width of disc on Finger III equal to half length of tympanum; relative lengths of fingers I <II <IV <III; subarticular tubercles prominent, low, rounded, none bifid; supernumerary tubercles not evident, palmar tubercle absent; prepollical tubercle elliptical. Hind limb robust; tibia length 44.7% SVL; foot length 44.2% SVL; calcar and tarsal tubercles absent; inner tarsal fold present on entire length of tarsus; outer metatarsal tubercle absent; inner metatarsal tubercle large, elliptical, not visible from above; toes long; relative length of toes I <II <III <V <IV; webbing basal between Toes I and II; webbing formula for other toes: II 2— 2 III 2— 3 IV 3— 1 V; subarticular tubercles small, rounded; supernumerary tubercles absent. Skin on dorsum and flanks graular; skin on throat, belly, and ventral surfaces of thighs granular, on other surfaces of smooth; cloacal tubercles and folds absent; pouch opening puckered; pouch filled with eggs. Dentigerous processes of the vomers inclined posteromedially, narrowly separated medially, between round choanae, bearing six teeth each.

Coloration in preservative: The dorsum of the head, body, and limbs are dark gray.

The flanks are dark brown. A dark brown canthal stripe is present; a white labial stripe borders the entire margin of the upper lip and extends posteriorly to the base of the forelimb. The posterior surfaces of the thighs are gray with faintly darker irregular markings. all ventral surfaces are dull tan with scattered small gray spots on the chest and belly.

Color in life: The dorsum is green with faint darker green paravertebral marks originating on the upper eyelids and becoming indistinct on the anterior part of the body ( Fig. 6 A). A narrow brown canthal stripe and a distinct white labial stripe are present. The postorbital region and the flanks are mottled green and tan. The iris is a silvery bronze with fine black flecks and reticulations.

Measurements (in mm): SVL 56.8, tibia length 25.4, foot length 25.1, head length 18.8, head width 19.5 interorbital distance 5.3, eyelid width 6.3, internarial distance 3.4, eye–nostril 5.0, eye diameter 6.9, tympanum diameter 4.4, orbit–jaw 2.6, nostril–jaw 4.1, thumb length 10.7, third finger length 18.0, width of disc on third finger 2.2.

Variation. There is little variation in size and proportions of the eight male paratypes ( Table 2). The head width is slightly greater than the head length, except in KU 212062 in which the ratio is 1.12. Likewise, in all specimens the interorbital distance is 0.83–0.98% (x = 0.91%) and the width of the upper eyelid, and the diameter of the tympanum is 0.55–0.76% (x = 0.65%) of the diameter of the eye. Males have 4–5 (x = 4.8) teeth on each vomerine process; vocal slits extend posterolaterally from the base of the tongue. Calling males have unpigmented nuptial excrescences.

In preservative, the dorsum is brown to pale gray with darker gray or brown markings consisting of broad paravertebral marks extending from the eyelids to the sacrum and a narrower V-shaped postsacral mark with the apex anteriorly. The dorsal surfaces of the limbs vary from no definite markings to transverse bars nearly as wide as the interspaces and as many as two on the forearm, four on the thigh, three on the shank, and two on the tarsus. A white labial stripe and dark brown canthal stripe and broad postorbital bar are present; in some specimens the postorbital bar extends to the middle of the flank. Three individuals have a narrow cream dorsolateral stripe extending from the margin of the upper eyelid to the groin. Two specimens have a discontinuous supracloacal white stripe. The venter is creamy tan with or without small dark brown flecks on the chest; the vocal sac in calling males is brown.

Color in life was obtained from a single color photograph of an adult male (KU 212055) that shows a tan dorsum with brown markings ( Fig. 6 B). A narrow pale cream dorsolateral stripe is barely evident, but the white labial stripe is evident. The iris is pale bronze with fine black reticulations.

Distribution and ecology: Gastrotheca aratia is known from elevations of 2560–2875 m in the northern part of the Cordillera Occidental of the Andes in northwestern Peru ( Fig. 5 ). The type locality, Cutervo is in the valley of the Río Chatano, a tributary of the Río Chamaya, which flows eastward into the Río Marañón. Much of the terrain in the immediate vicinity of Cutervo is cultivated. The holotype was turned up in a plowed field by day. Three males were calling from low bushes during a rain at night, and two young individuals were found in a cistern at night. All other specimens were extracted from terrestrial spiny bromeliads by day. Other anurans found in the vicinity of Cutervo include Hyloxalus elachyhistus , H. pulcherrimus , and Telmatobius latirostris . Three faded specimens (MCZ 5328–30) are from Querocotillo, a village northwest of Cutervo.

Life history: A brooding female contains a large number of small eggs in the brood pouch. This indicates that eggs hatch as tadpoles that complete their development in ponds.

Etymology. The specific name is derived from the Latin noun aratio, meaning plowed field. All specimens were found in, or at the edge of, plowed fields.

Remarks. Gastrotheca aratia seems to be surviving in cultivated areas, but possible use of herbicides or chemical fertilizers would endanger the species. Thus, G. aratia should be categorized as Vulnerable.

Figures

FIGURE 3. Dorsal and ventral coloration of preserved specimens of three species of Gastrotheca. A and D. G. monticola, KU 219771, 57.2 mm SVL, B and E. G. aguaruna, KU 212022, 50.8 mm SVL. C and F. G. aratia, KU 212067, 56.8 mm SVL.

FIGURE 5. Topographic map of the Andean region of northern Peru showing localities of known occurrence of Gastrotheca aguaruna (black dots) and G. aratia (red dots), and names of political regions and major mountain ranges discussed in the text.

FIGURE 6. Gastrotheca aratia. A, holotype, KU 212067 (holotype), adult female, 56.8 mm SVL, 8 km N Cutervo. B. KU 212055, male, 51.4 mm SVL, vicinity of Cutervo, Cajamarca, Peru.