Friday, April 20, 2018

[Herpetology • 2018] Pristimantis erythros • A New Species of Pristimantis (Anura, Craugastoridae) from the Cajas Massif, southern Ecuador

Pristimantis erythros  
Sánchez-Nivicela, Celi-Piedra, Posse-Sarmiento, Urgilés, Yánez-Muñoz & Cisneros-Heredia, 2018

A new species of Pristimantis is described from the highland paramos on the eastern slopes of the Cajas Massif, southern Andes of Ecuador, at 3400 m. This new species is characterized by having a distinctive reddish color, cutaneous macroglands in suprascapular region and surfaces of arm and legs, and by lacking dentigerous processes of vomers. The cutaneous macroglands are similar to those exhibited by several species of the Pristimantis orcesi group, and may suggest a close phylogenetic relationship. The new species could be a latitudinal substitution of Pristimantis orcesi in the southern Andes of Ecuador.

Keywords: Andes, glandular frog, paramo, Pristimantis erythros sp. n., taxonomy, Terrarana

Pristimantis erythros sp. n. 
Common name: English: Blood Rain Frog.
Spanish: Cutín de Sangre

Figure 4. Lateral, dorsal and ventral views of living specimens of Pristimantis erythros.
 Left: Male paratype (DHMECN 12102, SVL: 37.1 mm); right: Female holotype (DHMECN 12103, SVL: 39.1 mm).

Diagnosis: Pristimantis erythros differs from other species of the genus by the combination of the following characters: (1) Skin on head and dorsum granular, flanks and venter areolate with low warts; dorsolateral folds absent; discoidal fold weakly defined; (2) tympanic membrane and annulus present and visible, rounded, ca. 50% of eye diameter, upper half covered by parotoid macrogland; (3) snout short, rounded in dorsal and lateral views; (4) upper eyelid without tubercles, interorbital distance wider than width of upper eyelid (40%); cranial crests absent; (5) dentigerous process of vomers absent; (6) vocal slits and sacs present in males, nuptial pads absent; (7) Finger I shorter than II; discs laterally expanded with dilated pads and narrow fringes, (8) fingers with coarse lateral cutaneous fringes; (9) low ulnar warts in ventral view; radioulnar macroglands covering the upper surfaces of forearm; (10) heel and tarsus lacking tubercles; paracnemid macroglands on upper surfaces of legs, tarsi, and Toes IV and V; (11) inner metatarsal tubercle oval, not prominent, twice as large as outer metatarsal tubercle, outer metatarsal tubercle rounded and low, supernumerary tubercles low and indistinct; Toe V longer than III, disc of Toe III reaches distal border of penultimate subarticular tubercle on Toe IV, disc on Toe V reaches distal border of distal subarticular tubercle on Toe IV; (12) toes with conspicuous lateral fringes, extend to base of fingers, webbing absent; toe pads as large as or slight larger than those on fingers; (13) in life, dorsum uniformly burgundy, red to orange-red (reddish brown to burgundy in preserved) ; flanks, posterior surfaces of legs, groin, throat and venter crimson (dark reddish brown in preserved); iris dark brown with thin golden reticulations; ventral surfaces of hands and feet pinkish cream; (14) SVL in adult females 38.8–42.6 mm (x̄ = 40.3, n = 4), in adult males 36.8–37.1 mm (x̄ = 36.7, n = 2).

Etymology: The specific epithet erythros is derived from the Greek word for red, in allusion to the distinctive coloration of this species.

Figure 5. Comparison of Pristimantis erythros (top right) with Pristimantis orcesi (top left), Pristimantis pycnodermis (below left), and Pristimantis loujosti (below right).

Figure 6. Habitat of Pristimantis erythros in type locality.

Distribution, natural history, and extinction risk: Pristimantis erythros is only known from its type locality in the Cajas Massif. The area is covered by paramos dominated by grassland and shrubs, between 3450 and 3500 m (Fig. 6). Specimens were collected mainly in terrestrial bromeliads (Puya hamata) and grasses (Neurolepis villosa), near to small streams. Vocalizations were heard (but unrecorded) during daytime hours from 08h00 to 11h00 and from 17h00 to 19h00. Active individuals were observed from dusk until approximately 21h00, afterwards activity decreased. The new species was recorded in sympatry with Pristimantis aff. cryophilius, P. aff. orestes and P. aff. riveti.

The Paramos on the Cajas Massif (221000 h. approx.) appear well preserved. Part of its extension includes the Cajas National Park (28544 h). However, the continued changes on land cover and land use occurring in several areas over the massif on the buffer area of the national park and not protected nearest regions are leading to habitat loss (Hofstede et al. 2002). During a period of four (4) years (2014–2017), twenty six (26) localities in suitable regions (2500–3500 m) on the Cajas Massif were surveyed, no additional records of this new Pristimantis were added during these excursions mentioned above. It is probable that P. erythros inhabit only a single locality in an area of less than 1 km2. Finally, based on the small area of occupancy that might be restricted to the type locality which it is not under conservation in a protected area, we suggest that, it should be classified as Critically Endangered (CR) under the UICN criteria B1,B2ab(i,ii,iii,iv) (IUCN 2001).

 Juan C. Sánchez-Nivicela, Elvis Celi-Piedra, Valentina Posse-Sarmiento, Verónica L. Urgilés, Mario Yánez-Muñoz, Diego F. Cisneros-Heredia. 2018. A New Species of Pristimantis (Anura, Craugastoridae) from the Cajas Massif, southern Ecuador. ZooKeys. 751: 113-128.  DOI: 10.3897/zookeys.751.20541

Resúmen: Describimos una nueva especie de Pristimantis desde las laderas orientales del macizo El Cajas en los páramos andinos del sur de Ecuador a 3400 m.s.n.m. Esta nueva especie tiene un color rojizo distintivo y se caracteriza por tener macroglándulas cutáneas en varias regiones del cuerpo, de la siguiente manera: la región supraescapular, las superficies del antebrazo, parte superior del brazo, las manos y el borde de las piernas. Además, carece de procesos dentígeros en los vomerinos. Las macroglándulas cutáneas son similares a las presentes en el grupo de Pristimantis orcesi, y podrían representar una posición filogenética cercana. La nueva especie puede constituir una sustitución latitudinal de Pristimantis orcesi en los Andes sur de Ecuador.

Palabras clave: Andes, rana glandular, páramo, Pristimantis erythros sp. n., taxonomía, Terrarana

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