Phrynopus montium ( Shreve, 1938 )

May, Rudolf Von, 2017, Rediscovery of the Endangered frog Phrynopus montium (Shreve, 1938) (Amphibia, Anura, Craugastoridae) in the cloud forest of central Peru, Zootaxa 4338 (1), pp. 195-200 : 195-199

Rediscovery of the Endangered frog Phrynopus montium ( Shreve, 1938) (Amphibia, Anura , Craugastoridae ) in the cloud forest of central Peru

RUDOLF VON MAY 1 ,2,3

1 Museum of Zoology, Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA 2Museum of Vertebrate Zoology, University of California at Berkeley, CA 94720, USA 3Corresponding author E-mail: [e-mail]

Abstract

Phrynopus montium ( Shreve, 1938) was described from Cascas, Junín Department, Peru, at an undetermined elevation between 3000 and 4000 m a.s.l. in the Cordillera Central. With the exception of the type specimens used in the original description, no additional sightings of P. montium had been reported for 76 years. Additionally, its coloration in life, microhabitat use, and precise elevational distribution remained unknown. During a field expedition conducted in 2014, two individuals of P. montium were found at an upper cloud forest site in central Peru, 8.7 km south from Hacienda Cascas. Here, I describe the coloration in life, microhabitat use, and elevation of these individuals.

Key words: Amphibians, Andes, montane forest, terrestrial breeding frogs

Introduction

Phrynopus montium ( Shreve, 1938) is a small terrestrial breeding frog (Amphibia, Anura , Craugastoridae ) that was originally described from “Cascas, near Huasahuasi, Department of Junin, Peru,” at an undetermined elevation in the Cordillera Central. The description was based on four specimens measuring between 21 and 29 mm in “length of head and body” (≈ snout–vent length), although no precise information about the sex or reproductive condition was included; Shreve (1938) pointed out that the species lacks a tympanum and vomerine teeth (= dentigerous processes of vomers), both of which are characters shared by most species of Phrynopus ( Duellman & Lehr 2009) . Though Shreve (1938) did not provide information about the elevation of the type locality, the elevational range of P. montium was thought to be between 3000 and 4000 m a.s.l. ( Duellman & Lehr 2009) or up to 4012 m a.s.l. ( Rodríguez & Catenazzi 2017). Precise information about the habitat of P. montium has also remained unknown. Shreve (1938) did not mention the habitat, but it was assumed that the species might live in montane cloud forest or Andean valleys with scrub vegetation ( Icochea et al. 2004). Rodríguez & Catenazzi (2017: p. 403) suggested that the main habitat is Puna (also known as Andean grassland or Puna grassland). However, without new field observations, it has remained difficult to identify the primary habitat of this species.

Phrynopus montium is currently categorized as Endangered B1ab(iii) by the International Union for the Conservation of Nature and Natural Resources (IUCN) because its distribution is thought to cover a small geographic area (Extent of Occurrence <5,000 km 2) that has experienced habitat loss and degradation ( Icochea et al. 2004). The Peruvian Government recently categorized P. montium as Endangered following a nationwide assessment of threatened biodiversity (Ministerio de Agricultura y Riego, 2014). As a result, nine species of Phrynopus are currently categorized as threatened in Peru (Catenazzi & von May 2014).

Until recently, P. montium was considered to have a relatively wide distribution in central Peru, including the regions of Junín, Pasco, and Huánuco ( Icochea et al. 2004). However, the populations in Pasco and Huánuco represented two other species, P. kotosh and P. oblivius , that were described by Lehr (2007a). As a result, the known geographic range of P. montium was restricted to the type locality, Hacienda Cascas, Región Junín ( Lehr 2007a; Duellman & Lehr 2009). Thus, the precise geographic coordinates and elevation of the original collecting site, as well as the coloration in life, have remained unknown since the original description by Shreve (1938).

During a field expedition carried out in 2014, I collected several specimens of Phrynopus on the eastern part of the Cordillera Central, Región Junín. Close inspection of two of these specimens revealed that they belong to P. montium . Here, I provide the first description of its coloration in life, microhabitat use, and elevation of these individuals.

Materials and methods

I followed Lynch & Duellman (1997) for the general description format, and used the diagnostic characters of Duellman & Lehr (2009). Specimens were preserved in 96% ethanol and stored in 70% ethanol. Specimens were dissected to determine sex and maturity. I measured the following variables to the nearest 0.1 mm with digital calipers under a Zeiss Stemi 1000 stereoscope: snout–vent length (SVL), tibia length (TL), foot length (FL, distance from proximal margin of inner metatarsal tubercle to tip of Toe IV), head length (HL, from angle of jaw to tip of snout), head width (HW, at level of angle of jaw), eye diameter (ED), interorbital distance (IOD), upper eyelid width (EW), internarial distance (IND), eye–nostril distance (E-N, straight line distance between anterior corner of orbit and posterior margin of external nares). Fingers and toes are numbered preaxially to postaxially from I–IV respectively I–IV. To reduce reflections, preserved specimens were photographed submersed in ethanol. Photographs taken in the field were used for descriptions of color in life. Specimens were deposited in the herpetological collections of the Museo de Historia Natural, Universidad Nacional Mayor de San Marcos (MUSM) in Lima, Peru.

Field surveys took place on 12 September 2014. During approximately eight hours (9:00–17:00 h), two field assistants and I searched eight sites along the road between Cachiyacu (11°15'12.96" S, 75°34'48.36" W) and Hacienda Cascas (11°08'15.13" S, 75°36'02.36" W), Región Junín. Survey sites included Andean grassland (n = 3 sites), upper cloud forest (n = 2 sites), and open areas with scattered bushes next to agricultural fields (n = 3 sites). In addition to the specimens of P. montium reported here, I collected another species, P. juninensis , which had been previously collected in the vicinity of Cascas, the type locality for both P. juninensis and P. montium ( Duellman & Lehr 2009) . Data on P. juninensis will be presented separately in a study focusing on the phylogeny and morphology of the group (von May et al., unpublished data).

Results

I found two individuals of P. montium at one site located at 3,493 m a.s.l. (11°12'56.84" S, 75°35'26.59" W), 8.7 km south from Hacienda Cascas . Both individuals were found under rocks in an open area with scattered bushes, moss ( Sphagnum sp.), and bunchgrass ( Stipa sp.) between the road and a small (<0.5 ha) potato crop ( Figure 1 ). Below, I provide a brief description of the morphology, coloration in life, coloration in preservative, and natural history.

Morphology. The external morphology of the two specimens (MUSM 33259, 33260) largely matched the diagnosis and description provided by Shreve (1938). Specifically, I observed the following characteristics (observations by Shreve, if slightly different, included in parentheses): tongue suboval; no dentigerous processes of vomers (vomerine teeth none); snout rounded in dorsal and lateral views; loreal region concave; canthus rostralis distinct, curved; nostril closer to the tip of the snout than the eye; interorbital space broader than upper eyelid; tympanic membrane and tympanic annulus absent (no tympanum); tips of digits bulbous, rounded (not or but extremely feebly swollen); finger I shorter than finger II; toe I shorter than toe II; inner metatarsal tubercle ovoid (rather large but ill defined), outer metatarsal tubercle narrow, weakly defined (outer virtually indistinguishable from many surrounding poorly defined tubercles); skin on dorsum and flanks with scattered, low tubercles (granulate above, especially posteriorly; sides very coarsely granulate); skin on throat smooth, skin on chest and venter areolate (belly, chest, throat, and lower surface of thighs also very coarsely granulate); dorsolateral folds and discoidal folds absent (not indicated). I also reviewed the characteristics provided by Duellman & Lehr (2009), and one difference pertains the condition of the tympanic annulus. According to Duellman & Lehr (2009) the tympanic annulus is “visible beneath the skin.” However, this condition was not observed in the newly collected individuals reported here. It is also worth noting that the specimen shown in Figure 102 in Duellman & Lehr (2009; p. 118) likely represents a different species (i.e., not P. montium ) because it was collected at Maraynioc, Tarma Province, which is the type locality of P. oblivius and P. peruanus (Lehr 2007ab).

A dissection of the preserved specimens revealed that both are female. One of them, MUSM 33259, contained two ovarian eggs (diameter <2 mm) and the other, MUSM 33260, contained 15–20 ovarian eggs (diameter <1 mm) in each ovary. Individual body measurements (in mm) are as follows. MUSM 33259: SVL 26.3; TL 10.3; FL 10.7; HL 8.3; HW 8.9; ED 2.7; IOD 2.6; EW 1.5; IND 2.4; E-N 2.0. MUSM 33260: SVL 20.9; TL 8.1; FL 8.5; HL 7.1; HW 7.2; ED 2.3; IOD 2.0; EW 1.4; IND 1.8; E-N 1.4.

Coloration in life. Individuals of P. montium exhibited variable coloration in life ( Figure 2 ).

Individual MUSM 33259 had pale grayish brown dorsum with a pale, thin mid-dorsal stripe, 4–5 small pale yellow spots on each side of dorsum and one pale yellow spot on the left flank; dorsal surface of forearms and flanks colored as dorsum, slightly paler; side of head and groin with no markings; posterior surfaces of thighs colored as dorsum, with 2–3 small pale yellow spots; throat, chest, and belly pale gray; fingers I and II cream above and pale salmon below, fingers III and IV gray above and dark gray below toes I–III pale gray, toes IV–V gray; palmar and plantar surfaces, including subarticular tubercles, dark gray; iris bronze with fine black reticulations. Individual MUSM 33260 had grayish brown dorsum with a pale, thin mid-dorsal stripe and a small pale yellow spot on each side of dorsum; dorsal surface of forearms and flanks reddish brown; side of head with a pale gray bar under the eye; groin and anterior surface of thighs reddish brown; posterior surfaces of thighs colored as dorsum, with no spots; throat, chest, belly, and ventral surface of thighs salmon; fingers I and II tan, fingers III and IV pale brown; toes I–III pale tan, toes IV–V gray; palmar and plantar surfaces, including subarticular tubercles, dark gray; iris bronze with fine black reticulations.

Coloration in preservative. Both specimens of P. montium exhibit similar coloration in preservative. Specimen MUSM 33259 with dorsum gray with small white flecks; throat and chest pale cream and gray, with pale mid-ventral stripe; ventral surfaces of hands, forearms, and feet pale gray; fingers I and II white above and below, fingers III and IV pale gray above and below; toes I–III white above and below, toes IV–V light gray above and below; iris uniformly gray. Specimen MUSM 33260 as above, except that ventral surfaces of hands and forearms are primarily pale cream instead of gray. A lateral view of the head and a ventral view of left hand of both specimens are provided in Figure 3 .

Natural history. Both specimens of P. montium were found under rocks in an open area with scattered bushes, moss ( Sphagnum sp.), and bunchgrass ( Stipa sp.). This site is next to an area of approximately 100× 200 m used for potato cultivation, which, in turn, is surrounded by a larger area (3.50× 1.75 km) of upper montane cloud forest. Thus, P. montium might inhabit montane forest in addition to scrub vegetation. Two other amphibians, P. juninensis and the marsupial frog Gastrotheca griswoldi , were found under rocks in the surrounding areas.

Figures

FIGURE 1. Site near road between Cachiyacu and Hacienda Cascas, Región Junín, Perú, where two individuals of Phrynopus montium were found in September 2014. Photo by R. von May.

FIGURE 2. Lateral and ventral views of live individuals of Phrynopus montium, found in September 2014 near the type locality. A – B (MUSM 33259, SVL 26.3 mm), C – D (MUSM 33260, SVL 20.9 mm). Photos by R. von May.

FIGURE 3. Lateral view of head and ventral view of left hand of preserved individuals of Phrynopus montium. A – B (MUSM 33259), C – D (MUSM 33260). Photos by R. von May.