Sunday, April 11, 2021

[Herpetology • 2021] Gastrotheca gemma • A New Species of Marsupial Frog (Anura: Hemiphractidae: Gastrotheca) from the Cordillera de Colán in northeastern Peru

Gastrotheca gemma
Venegas, García-Ayachi, Echevarría, Paluh, Chávez–Arribasplata, Marchelie & Catenazzi, 2021

Photographs by Axel Marchelie.

We describe a new species of marsupial frog, genus Gastrotheca, using morphological characters and molecular data as lines of evidence. The new species was discovered in the páramo and the ecotone between páramo and humid montane forest of Cordillera de Colán, at elevations between 3136 and 3179 m a.s.l., in northeastern Peru. The new species is distinguished from all its congeners by the combination of the following characters: coarsely granular skin on dorsum, a green dorsal coloration without pattern, finger I shorter than finger II, turquoise iris, and a venter without blotches, flecks or dots. Furthermore, we include a detailed osteological description of the new Gastrotheca species based on Micro-CT scanning. Based on our phylogenetic analyses, the new species belongs to the Gastrotheca marsupiata species group, is sister to G. oresbios and closely related to G. psychrophila, G. spectabilis, G. stictopleura and one undescribed species. Additionally, we test for the presence of the fungal pathogen Batrachochytrium dendrobatidis (Bd). No Bd infection was detected for Gastrotheca gemma sp. nov. specimens but Bd prevalence was detected among syntopic frogs.

Keywords: Amphibians, Andes, Batrachochytrium dendrobatidis, Gastrotheca abdita, Hemiphractidae, osteology, phylogeny


Figure 4. Three living adult specimens of Gastrotheca gemma sp. nov.:
(A–B) dorsolateral and ventral views of female holotype (CORBIDI 21238), 69.7 mm SVL, with a zoom of its eye;
(C–D) dorsolateral and ventral views of the adult male paratype (CORBIDI 21246), 57.0 mm SVL;
(E–F) dorsolateral and ventral views of the adult male paratype (CORBIDI 21247), 59.5 mm SVL, with a zoom of its eye.
Photographs by Axel Marchelie.

Figure 2. Preserved holotype of Gastrotheca gemma sp. nov. (CORBIDI 21238; female, SVL = 69.7 mm) in dorsal (A) and ventral (B) views.

Gastrotheca gemma sp. nov. 
Diagnosis: Assigned to the genus Gastrotheca by females possessing a closed brood pouch on the dorsum. A moderately large species (69.7 and 71.8 mm SVL in two females, 56.9 and 59.5 mm SVL in two males), with: (1) tibia length 57–59% SVL, longer than foot; (2) interorbital distance greater than width of upper eyelid (161–169%); (3) skin on dorsum coarsely granular in females and granular in males, not co-ossified with skull, lacking transverse ridges; (4) supraciliary processes absent; (5) heel lacking calcar or tubercle; (6) tympanic annulus wrinkled or tuberculate; (7) Finger I slightly shorter than Finger II, width of discs wider than digits; (8) finger webbing present basally, only between III and IV; (9) foot webbing between external toes extending to nearly antepenultimate subarticular tubercle on Toe IV, to penultimate subarticular tubercle on Toe V; (10) in life, dorsum green with numerous minute black flecks in females and green with scattered yellow dots in males, paravertebral marks absent; (11) head markings consisting of a chocolate or pale green labial stripe in females and males, respectively; (12) dorsolateral stripe absent; (13) flanks uniformly green in females and green with numerous dark green irregular flecks in males; groin yellowish green in both sexes; anterior surfaces of thighs green, posterior surfaces of thighs yellowish green with scattered irregular black flecks in females and dense black reticulations in males; ventrolateral region yellowish green; irises silvery with a light blue hue or turquoise with thin black reticulations with or without an orange ring; (14) gular region and chest green in females and yellowish green in males; venter yellowish green with or without a big dark grey patch in the middle in females and venter greenish cream in males; ventral surface of thighs yellowish green with a dark greyish brown patch on the centre in females and thighs pale brownish cream in males; palms, soles and ventral surface of tarsus dark grey or dark greyish brown; (15) brood pouch single, dorsal; (16) reproduction mode direct development.

Etymology: The specific epithet comes from the Latin word “gemma”, a substantive meaning precious stone or gem. This specific name is used in apposition and refers to the turquoise coloration, in life, of the eyes of the new species of marsupial frog, which resembles the coloration of a turquoise stone.

Figure 8. Skeleton and 34 embryos in pouch of Gastrotheca gemma sp. nov. (CORBIDI 19396) as visualized via Micro–CT scanning in dorsal (A) and right lateral (B) views. (A) Scale bar = 10 mm.


 Pablo J. Venegas, Luis A. García-Ayachi, Lourdes Y. Echevarría, Daniel J. Paluh, Juan C. Chávez–Arribasplata, Axel Marchelie and Alessandro Catenazzi. 2021. A New Species of Marsupial Frog (Anura; Gastrotheca) from the Cordillera de Colán in northeastern Peru. Vertebrate Zoology. 71: 201-218. DOI: 10.3897/vz.71.e60097