Osteocephalus mimeticus ( Melin, 1941 )

Jungfer, Karl-Heinz, 2010, The taxonomic status of some spiny-backed treefrogs, genus Osteocephalus (Amphibia: Anura: Hylidae), Zootaxa 2407, pp. 28-50 : 39-41

Osteocephalus mimeticus ( Melin, 1941)

( Fig. 6 )

Hyla mimetica Melin, 1941

Osteocephalus pearsoni – Trueb & Duellman 1971 (partim) Hyla triangulum – Duellman 1974 (synonymized mimetica with triangulum ) Hyla elkejungingerae Henle, 1981

Hyla elkejungingerae – Henle et al. 1983

Hyla elkejungingerae – Frost 1985

Osteocephalus verruciger – Schütte & Spieler 1986 Osteocephalus elkejungingerae – Henle 1992 (nov. comb.) Osteocephalus mimeticus – Smith & Noonan 2001 (nov. comb.) Osteocephalus elkejungingerae – Frost 2009

Hyla mimetica was described from two syntypes both bearing GNM “no. 469” from the village of Roque, Departamento San Martín, Peru. I designate the specimen that coincides in details of coloration with Melin’s (1941) Fig. 10a, which his description apparently is based on, a subadult specimen of 34.0 mm SVL, as the lectotype.

This frog has been confused many times since its description. One reason may be the fact that the type specimens are juvenile frogs with rows of bold paravertebral spots on the dorsum lacking many characteristic features of adult male Osteocephalus . Trueb & Duellman (1971) referred an adult specimen from Yaupi, Río Paucartambo, Departamento Pasco, Peru (KU 136312) to O. pearsoni and illustrated it as such. The dorsal coloration of the holotype apparently led Duellman (1974) to synonymize Hyla mimetica with Hyla triangulum Günther, 1869 (= Dendropsophus triangulum ). However, the lectotype (he mentions a frog of 23.5 mm SVL; apparently the other syntype) lacks the axillary membranes and glandular thoractic patches of frogs of the Dendropsophus leucophyllatus group, which triangulum is a member of. Henle (1981) described Hyla elkejungingerae on the basis of juveniles collected as tadpoles and raised in captivity from Boquerón del Padre Abad, Departamento Ucayali, Peru. He later transferred it to Osteocephalus when frogs raised to adult size and more specimens were available ( Henle 1992). Before, Frost (1985) had listed the taxon under Hyla elkejungingerae , but added a note by Hoogmoed that it was likely to be a synonym of Osteocephalus taurinus . Eric Smith (pers. comm. 2002) and I independently inspected the holotype of Hyla mimetica and agree that it is a valid taxon in the genus Osteocephalus . Earlier, Smith & Noonan (2001), without further comment, had referred to material examined by them as Osteocephalus mimeticus in their description of Osteocephalus exophthalmus . The species (as Osteocephalus elkejungingerae ) was described in detail by Henle (1992), so it need not be repeated here. The lectotype agrees with the holotype of Hyla elkejungingerae , also a subadult (22 mm SVL) as well as with the large series of “topotypes” at the ZFMK, namely the subadult specimens (e. g. ZFMK 39164, 40152–3). The lectotype of Hyla mimetica has still retained some juvenile characters: Large white supralabial spots (reduced to a large subocular mark in many adults), dark paravertebral markings (a uniform dorsum or variable markings on the entire dorsum in adults), light elbows, knees and tibiotarsal articulations (dark like the rest of the extremities in adults). But the iris coloration, black with some golden blotches (a character shared among the genus only with the allopatric Colombian O. carri ) is already reminiscent of that of an adult. In contrast, recently metamorphosed juveniles have bright red irises. Live subadults have intermediate irises with black blotches on light red ground. The red color quickly fades in preserved frogs. Sexes at this stage can already be identified by dorsal skin structure. The specimen’s back is smooth, indicating that it is a female. The ontogenetic change in this species has been described and illustrated several times (Henle 1981, Henle et al. 1983, Schütte and Spieler 1993) under various names. Females from the type locality of Hyla elkejungingerae that I placed together with a male from Tarapoto, about 45 km east of the type locality of Hyla mimetica , laid eggs that were fertile. Frogs raised from these eggs were also fertile. The maximum size for males measured is 62.7 mm SVL from Boquerón del Padre Abad, Departamento Ucayali, Peru ( Henle 1992), the largest female, KU 209454 from the Río Cainarache, 33 km NE Tarapoto, San Martín, Peru, is 82.7 mm in SVL.

Measurements of the lectotype of Hyla mimetica (in mm): SVL 34.0; HL 12.5; HW 12.0; TL 23.0; FL 12.6; ED 4.3; TD 2.1; FD 1.8; EN 3.6; IN 2.8; TE 1.9.

Distribution: Osteocephalus mimeticus is a widespread species in the Andean foothills from about 260 to 1650 m a.s.l. from the Huancabamba Depression southward from Departamento San Martín, Peru, at least to Departamento Cuzco, Peru. I have seen photographs of a preserved specimen from Pilon Lajas, Departamento Beni, Bolivia, that I tentatively identified as O. mimeticus . This would be the southernmost locality record of the species. Similar frogs from north of the Huancabamba Depression in the Departamentos Amazonas and Cajamarca, Peru, and adjacent Provincia de Loja, Ecuador, represent an undescribed species most closely related to O. verruciger .

Figures

FIGURE 6. Osteocephalus mimeticus. a. Adult female, 75 mm SVL, from Boquerón del Padre Abad, Ucayali, Peru. b. Adult male, 63 mm SVL, not in breeding condition. c. Recently metamorphosed juvenile, 19 mm SVL, b and c both from Tarapoto, San Martín, Peru.