Nymphargus chancas Duellman & Schulte 1993
Creators: name: Twomey, Evan
name: Delia, Jesse
name: Castroviejo-Fisher, Santiago
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Amphibia
Anura
Centrolenidae
Nymphargus
Nymphargus chancas

description: Nymphargus chancas (Duellman & Schulte 1993)
Figure 27
Cochranella chancas Duellman and Schulte 1993. Holotype KU 211778, an adult male from “west slope of Abra Tangarana, 7 km by road northeast of San Juan de Pacaysapa (06°12’ S, 76°44’ W, 1080 m), Provincia Lamas, Departamento San Martín, Peru ”.
Nymphargus chancas— Cisneros-Heredia and McDiarmid 2007.
Background information. This species was described from a single adult male collected in Abra Tangarana, San Martín, Peru (Duellman & Schulte 1993). It was placed in the ocellata group due to the combination of white parietal peritoneum, clear visceral peritoneum, humeral spines in males absent, and vomerine teeth absent. This group was later described as a new genus Nymphargus (Cisneros-Heredia & McDiarmid 2007), and chancas was placed in this genus due to the combination of characters mentioned above, as well as its absence of hand webbing—a synapomorphy of Nymphargus. This species was later registered from the Cordillera del Condor in Ecuador (Guayasamin & Bonaccorso 2011).
New data. Since 2005 we have encountered this species in two localities in northern San Martín (Fig. 14). In 2005, two individuals were found by day in a small stream roughly 25 km SW from Tarapoto (approx. 6°35'38.10"S, 76°34'17.24"W, 1131 m). On 6 June 2011 two adult males (CORBIDI 14148 and CORBIDI 10471) were collected from a small stream 7.5 km SE from the type locality (6°19'12.83"S, 76°41'42.71"W, 1003 m; Fig. 27). In addition, we have seen photographs of specimens from the village of Yurilamas (approximately 6°14'S, 76°32' W, record courtesy M. Fashé) and a site roughly 14 km SE from the town of Shamboyacu, San Martín, Peru (7°4'8.9''S, 76°0'55.2''W, 1122 m, voucher specimens CORBIDI-HE-2010-8865 and CORBIDI-HE-2010-8866, record courtesy P. Venegas).
Variation. We noted variation in the prominence of yellow dorsal flecks, and rapid color-pattern changes. While all individuals we have seen possess distinct yellow flecks on the dorsum, the lone individual from Yurilamas has large, bright yellow flecks on the dorsum, appearing almost spotted. However, individuals seem to be capable of undergoing relatively rapid and dramatic color-pattern changes. For example, one of the individuals collected from Abra Tangarana had prominent occellations when we first found it in the field, but these quickly faded after capture and the frog took on the grayish-green dorsal coloration typical of this species. Iris color was described as pale yellowish-bronze in the original description (Duellman & Schulte 1993). In the specimens we have collected, iris color would be better described as silvery-white with a faint yellow suffusion throughout, and a horizontal black bar through the middle of the eye.
Distribution and ecology. Nymphargus chancas is distributed throughout northern San Martín at elevations over 1000 m. Its distribution extends into southern Ecuador, where it was collected between 1256–1430 m (Guayasamin & Bonaccorso 2011). This species seems to be associated with small creeks with thick forest cover. Reproductive behaviors such as oviposition and calling have not yet been observed in this species.
Taxonomic remarks. Our phylogenetic results revealed that Nymphargus chancas is paraphyletic. Of the three specimens included in the phylogenetic analyses, two of them cluster together as sister to N. puyoensis Flores and McDiarmid (1989) while the third one (QCAZ 41590) is sister to N. puyoensis (Fig. 2b). Nonetheless, this third specimen is from Zamora-Chinchipe province in Ecuador and may represent a misidentification or an undescribed species. However, this specimen shows no differences with the holotype of N. chancas (J.M. Guayasamin, pers. comm.). Nymphargus chancas and N. puyoensis are easily diagnosed on the basis of vomerine teeth (present in N. puyoensis, absent in N. chancas) and dorsal coloration (dull yellowish-green with minute yellow flecks in N. chancas vs. dark green with low, flat warts corresponding to yellowish-green spots).
description: Published as part of Twomey, Evan, Delia, Jesse & Castroviejo-Fisher, Santiago, 2014, A review of Northern Peruvian glassfrogs (Centrolenidae), with the description of four new remarkable species, pp. 1-87 in Zootaxa 3851 (1) on page 46, DOI: 10.11646/zootaxa.3851.1.1, http://zenodo.org/record/286921