Pristimantis muchimuk Barrio-Amorós, Brewer-Carías & Mcdiarmid, 2010, sp. nov.
Creators: name: Barrio-Amorós, César L.
name: Brewer-Carías, Javier Mesa Charles
name: Mcdiarmid, Roy W.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Amphibia
Anura
Strabomantidae
Pristimantis
Pristimantis muchimuk

description: Pristimantis muchimuk sp. nov.
(Figures 1–3)
Common name in English: Muchimuk rain frog. Common name in Spanish: Ranita muchimuk.
Holotype. MHNLS 19652, an adult female from the base camp of the Muchimuk-Expedition 2009, collected by Igor Elorza, Javier Mesa and Charles Brewer-Carías on a step of the northern face of Churi-tepui, 05º 16’ 45’’ N, 62º 00´56’’ W, 2325 masl, Estado Bolívar, Venezuela (Fig. 4–5).
Diagnosis. Pristimantis muchimuk is a small (SVL 25.2 mm) species that we place in the diverse Pristimantis unistrigatus group sensu Hedges et al. (2008), distinguished by Finger I shorter than Finger II, Toe V longer than Toe III, extending to the distal subarticular tubercle on Toe IV, cranial crests absent, and vomerine teeth present. Pristimantis muchimuk is characterized by: (1) dorsal skin smooth to warty, warts smooth, low and flat (smooth in preservative), with a barely distinguishable middorsal raphe; ventral skin smooth; (2) tympanic annulus and membrane absent; (3) snout rounded in dorsal view, nearly truncate in profile; canthus rostralis rounded; (4) upper eyelid smooth, with one barely discernible tubercle on each eyelid; (5) choanae small, oval; vomerine dentigerous processes horizontal, small, posterior and medial to choanae, each bearing 3 teeth; tongue rounded posteriorly; (6) presence of vocal slits and nuptial pads not known; (7) Finger I shorter than Finger II; (8) fingers with lateral keels; (9) ulnar tubercles absent; (10) tarsal tubercles and calcars absent; (11) inner metatarsal tubercle oval, three times the size of the round outer metatarsal tubercle; (12) toes with lateral fringes; basal webbing between Toes III-IV-V; Toe V longer than Toe III; (13) in preservative, dorsal surfaces of body and limbs dark brown, almost black, with many small whithish spots; ventral surfaces dirty white, with brown melanophores concentrated on chin and throat. In life: dorsum black with many small yellow spots; flanks dark brown with pinkish white flecks; venter white.
Comparison with other species. Pristimantis muchimuk (Fig. 1A) is unique among congeners inhabiting the highlands and mountain slopes in the Western Guiana Shield (Venezuela and Guyana) by the following combination of characters: tympanum absent, skin on dorsum and venter smooth, only one ill-defined tubercle on each upper eyelid, fingers and toes with well-developed lateral fringes, basal webbing between Toes III–V, and dorsum dark brown with small yellow and pink spots (in life), which become white in preservative. The following Guayanan Pristimantis are compared with P. m u c h i m u k (characters of the new species in parentheses), as all are endemics from granitic or sandstone uplands or highlands (tepuis). Pristimantis auricarens (Myers & Donnelly) from Auyantepui has tubercular dorsal skin (slightly warty to smooth) and areolate ventral skin (smooth), snout truncate to acutely rounded dorsally (rounded), rounded in profile (nearly truncate). Pristimantis avius (Myers & Donnelly) from Tamacuari, has tubercular dorsal skin (slightly warty to smooth), distinct tympanum (absent), no lateral fringes on fingers (present), and females are larger, up to 33 mm (25 mm). Pristimantis cantitans (Myers & Donnelly) from Cerro Yaví, has a visible tympanum (absent), upper eyelid with small warts (smooth, with only one barely distinguishable tubercle), small, low nonconical calcar tubercles (absent), lip bars present (absent), larger size, females up to 45 mm (25 mm), and an axillary tubercle (absent). Pristimantis dendrobatoides Means & Savage, from Wokomung, Guyana, has verrucose dorsal skin (slightly warty to smooth), distinct tympanum (absent), black dorsum with several large red spots, ventral parts of hind limbs bright red in life (no red color). Pristimantis inguinalis (Parker) from the Guianas, has granular dorsal skin (slightly warty to smooth), tubercles on eyelids (absent), and a yelloworange ocellus in cloacal region (absent). Pristimantis jester Means & Savage, from Wokomung, Guyana, has a snout dorsally subovoid (rounded), and laterally rounded (nearly truncate); a concave canthus rostralis (rounded), no fringes on fingers or toes (present), the coloration include red on the flanks (no red). Pristimantis marahuaka (Fuentes & Barrio-Amorós) from Cerro Marahuaka is most similar morphologically (see Fuentes & Barrio-Amorós 2004); though it lacks webbing between toes (basal webbing present between toes III-V), subarticular tubercles are prominent (little notable), ventral skin areolate to granular (smooth), disc on finger II 2.4 times wider than adjacent phalanx (2.0), and different color, dorsum pale brown to yellowish brown in preservative, garnet brown in life with or without small silvery spots (dark brown with white spots); venter is dirty white or reticulated with brown (white). Pristimantis marmoratus (Boulenger) from lowlands, uplands and highlands of the Guiana Shield, has a tubercular dorsal skin (slightly warty to smooth), tympanum distinct (absent), limbs barred (without bars), and a different habitat, rain to cloud forests in lowland and uplands up to 1400 m of the Guiana Shield (vs. non-gramineous tubiform meadows on rocky summit on a single tepui at 2325 m). Pristimantis memorans (Myers & Donnelly) from Tamacuari has tubercular dorsal skin (slightly warty to smooth) and areolate venter (smooth), tympanum distinct (absent), dark lip bars (absent), truncate finger discs (rounded). Pristimantis pruinatus (Myers & Donnelly) from Cerro Yaví, has granular dorsal skin (slightly warty to smooth) and areolate venter (smooth), tympanum small but visible (absent), lateral keels on fingers absent (present), and small, non-conical calcar tubercles (absent). Pristimantis pulvinatus (Rivero) from Sierra de Lema has many tubercles on dorsal surfaces (smooth), tympanum evident (absent), fingers and toes without lateral fringes (present), ulnar tubercles present (absent). Pristimantis saltissimus Means & Savage, from Wokomung, Guyana, has snout profile subelliptical dorsally (rounded) and acuminate laterally (nearly truncate); canthus rostralis concave (rounded); fringes on fingers and toes absent (present) and no webbing between toes (present). Pristimantis sarisarinama Barrio-Amorós & Brewer-Carías from Sarisariñama-tepui, has dorsal skin shagreneed (slightly warty to smooth), ventral skin areolate (smooth), evident tympanum (absent), fingers without lateral keels (present), toes without webbing (present) and keels (present). Pristimantis yaviensis (Myers & Donnelly) from Cerro Yaví, has flat tubercles on the upper eyelid (absent), and scattered warts on the dorsal skin (slightly warty to smooth, warts absent), fingers and toes lacking fringes (present). Pristimantis yuruaniensis Rödder & Jungfer from Yuruani-tepui lacks vomerine dentigerous processes (present), has a small but distinct tympanum (absent), and fingers and toes lack lateral fringes (present).
The other species of Pristimantis in the Guiana region belong to the Pristimantis conspicillatus Group (sensu Lynch & Duellman 1997; Hedges et al. 2008). These are P. chiastonotus, gutturalis, vilarsi, and zeuctotylus, which are widely distributed throughout the lowlands. All have a long snout and the first finger longer than the second.
Description. Body slender (Fig. 1 B). Head slightly wider than body, slightly longer than wide; HL 39.2% of the SVL; rounded in dorsal view (Fig. 2A), nearly truncate in profile (Fig. 2 B); nares not protuberant, directed laterally; canthus rostralis rounded, soft; loreal region concave; lips not protruding; one barely discernible tubercle on each eyelid, remainder of head without tubercles; interocular region barely wider tan upper eyelid width; temporal region almost vertical; supratympanic fold well defined, tympanic annulus and membrane absent. Choanae small, oval, not concealed by palatal shelf of maxillary arch, vomerine dentigerous processes barely distinguishable, transverse, posterior to level of choanae, bearing three teeth each; tongue rounded posteriorly.
Skin on dorsum smooth, without tubercles; dorsal surfaces of limbs smooth, middorsal raphe barely distinguishable, anal sheath and tubercles in cloacal region absent; skin on flanks, throat, chest, belly and ventral surfaces of hind limbs smooth.
Hand (Fig. 3A) with a thenar tubercle ovoid; palmar tubercle deeply bifid; supernumerary tubercles present, large, low, non-protruding; subarticular tubercles round, little notable; fringes well developed on fingers; Finger I shorter than II (its length 87% of II); relative length of fingers III>IV>II>I; finger discs expanded, rounded, on Fingers III and IV twice width of adjacent phalange; on Finger II 1.5 the width of adjacent phalange, and on Finger I slightly wider than adjacent phalange; all discs with ventral pads. Ulnar fold and tubercles absent.
Foot length 40.4% of SVL (Fig. 3 B); calcar, tarsal tubercles, and tarsal fold absent. Inner metatarsal tubercle oval, 3 times size of round outer metatarsal tubercle; supernumerary tubercles present, numerous, small; subarticular tubercles round, little notable; toes with well-developed dermal fringes; basal webbing between Toes III-IV-V; relative length of the toes IV>V>III>II>I; discs on toes round, smaller than those on fingers; disc on Toe IV slightly smaller than disc on Finger III. When adpressed, tip of disc on Toe V slightly surpasses distal subarticular tubercle of Toe IV; tip of disc on Toe III slightly surpasses penultimate subarticular tubercle of Toe IV.
Color in preservative: dorsal surfaces of body and limbs uniform dark brown with profusely scattered small white spots; palmar surfaces of Fingers I and II dirty white, those of Fingers III and IV with many dark brown flecks; plantar surfaces of Toes I–III white, rest of plantar surfaces with dark brown flecks, darkest laterally; ventral surfaces dirty white with few brown flecks on belly and chest, and more profuse on throat. Iris gray; palpebral membrane with a profusion of melanophores inferiorly (Fig. 2 B).
Color in life (from a color photograph; Fig. 1A): dorsal ground color uniform reddish brown, with many small yellow, mostly round, spots dorsally and many small pinkish white spots on flanks and limbs. Venter white. Iris gray with fine black reticulation.
Measurements of the holotype. SVL: 25.2; ShL: 12.4; FL: 10.2; HW: 9.1; HL: 9.9; UEW: 2.4; IOD: 2.6; ED: 3.0.7; FD: 1.2; T4D: 1.1; ETS: 4.1; 1FiL: 2.9; 2Fil: 3.3.
Remarks. The holotype is slightly dehydrated (Fig. 1 B) because it was preserved directly in alcohol, without fixing it in formalin. Some characters are still easily observed (fringes on fingers and toes, folds on forearms and tarsi), but should be compared with future living conspecific individuals or specimens fixed in formalin.
Distribution. The species is known only from Churi-tepui (Fig. 4), one of the 12 tepuis forming the Chimanta massif. The summit area of Churi-tepui is 47.5 km2, whereas the total summit area of Chimanta is 623 km 2, and the slope area is 915 km 2 (McDiarmid & Donnelly 2005). To date, Pristimantis muchimuk is the only species of the genus described for the Chimanta massif. The species Eleutherodactylus sp. I mentioned by McDiarmid & Donnelly (2005) from Murey (= Eruoda) tepui in the Chimanta massif probably represent a different undescribed species (see Discussion). Fig. 5 shows the distribution of P. m u c h i m u k and the rest of Venezuelan species south of the Orinoco river except P. vilarsi (see distribution map in Barrio-Amorós & Molina 2006).
Conservation. We recommend that the UICN status of P. m u c h i m u k must be Data Deficient (DD) (according to Stuart et al. 2008). Much research about the population status must be done in the Chimantá massif, but the new species seems to be rare, as we only found one specimen in four visits and Gorzula (1992) never found it.
Habitat and Natural History. The single specimen was found after rain, during the day, on a leaf of a fallen Brochinnia hechtioides (Bromeliaceae). The frog was apparently disturbed by human activity, and consequently visible during daylight. The habitat is known as “Non-Gramineous tubiform meadows” (sensu Huber 1995) on a flat swampy surface, with a height of no more than one meter, and predominance of Brocchinia hechtioides, Orectanthe ptaritepuyana, Heliamphora heterodoxa, Pterozonium sp., and Drosera sp. In the vertical crevices nearby there is a dwarf forest of the dwarf tree Bonnetia roraimae with intermittent streams running in the rainy season.
Etymology. Muchimuk refers to a demon in the mythology of the indigenous Pemon people. The demon has avian form, like a giant raptor, and takes humans and other beasts for food. It inhabits the summits of the Chimantá and Tramén tepuis. Muchimuk is also the name of the Expedition made in May 2009 to explore different galleries of the Charles Brewer cave system. The specific name is used as a noun in apposition.
description: Published as part of Barrio-Amorós, César L., Brewer-Carías, Javier Mesa Charles & Mcdiarmid, Roy W., 2010, A new Pristimantis (Anura, Terrarana, Strabomantidae) from Churi-tepui in the Chimanta massif, Venezuelan Guayana, pp. 35-44 in Zootaxa 2483 on pages 36-40, DOI: 10.5281/zenodo.195474