Two New Species of Centrolenella (anura: Centrolenidae) from Northwestern Peru

Two new species of Centrolenella are described from the Pacific versant of the Andes in northern Peru (Rio Zana, Cajamarca Department). These constitute the first records for the genus on the western slopes of the Andes in Peru. Centrolenella euhystrix, a large species (males to 31.3 mm, females to 33.6 mm snout-vent length), has a distinctive coloration (dark greenish black when active at night), broad digits, and large hands. Males of this species have very spinose dorsal skin and lack humeral spines. Although males of C euhystrix call from rock ledges in or along cascading streams, an unusual calling site for Centrolenella, neither egg masses nor reproduction were observed in this species. Centrolenella hesperia is a smaller species (males to 27.3 mm, females to 28.8 mm snout-vent length) which lacks a typanum, is bright green when active, and has a distinctive lateral white stripe from the snout to the groin. Males of this species have spinose dorsal skin and humeral spines. The reproductive behavior, vocalisations, and larval morphology of C. hesperia are similar to those known for other species of Centrolenella except that females have an unusual behavior at the clutch and egg masses contain empty capsules. The intercalary elements in these species are mineralized; the nature of this element in the Centrolenidae and other frogs is discussed. Resumen.•Se describen dos nuevas especies de Centrolenella de la vertiente pacifica de los Andes en el norte del Perú (Río Zana, Departamento de Cajamarca). Estas especies se componen el primer registro del género en Perú occidental. Centrolenella euhystrix es una especie grande (los machos alcanzan a 31.3 mm de longitud corporal y las hembras a 33.6 mm) que tiene una coloración distintiva (negro verdoso oscuro durante la actividad nocturnal), los dedos anchos, y las manos grandes. Los machos de esta especie son muy espinosos y carecen de espinas humerales. Aunque los machos de C. euhystrix cantan desde anaqueles rocosos en torrentes, o a lo largo de los mismos, un sitio de canto poco frecuente para Centrolenella, ni masas de huevos ni la reproducción fueron observadas en esta especie. Centrolenella hesperia es una especie más pequeña (machos hasta 27,3 mm de longitud corporal, hembras hasta 28.8 mm) que carece de un tímpano, es verde brillante cuando está activa, y tiene una raya lateral blanca desde el hocico hasta la ingle. Los machos de esta especie son también espinosos y tienen espinas humerales. El comportamiento reproductivo, las vocalizaciones, y la morfología larval de C. hesperia son similares a aquellas conocidas de otras especies de Centrolenella, menos que las hembras muestran un comportamiento extraña a la nidada, y que las masas de huevos contienen cápsulas vacias. Los elementos intercalares de estas especies están mineralizados; se discute la forma de este elemento en las Centrolenidae y otras ranas. VOLUME 103, NUMBER 3 747 Fig. 1. Map of the central Andes of southern Ecuador and northern Peru showing the Monte Seco area (star), the type locahty for Cenirolenella euhystrix and C. hesperia, and all other localities (dots) at which species of Cenirolenella are known to occur. The Hght hatching indicates areas between 1000 m and 3000 m; darker areas indicate those regions above 3000 m. The Huancabamba Depression of northern Peru and southem Ecuador has only a few, disjunct areas above 3000 m. Many frogs of the genus Cenirolenella (Centrolenidae) are known from the eastern Andean slopes of Colombia, Ecuador, and Peru (Frost 1985), and new species are being discovered at an astonishing rate (Duellman &Burrowes 1989;nores 1985,1987;nores & McDiarmid 1989). Cannatella & Duellman (1982) noted 10 species in Peru (nine discovered since the mid-1970s), and indicated five undescribed species from the Amazonian slopes. Although Cenirolenella is known from the western foothills and slopes of the Andes in Colombia and Ecuador, none has been reported from Peru's western slopes. Herein we describe two species from the Pacific versant of northern Peru about 350 km south of the nearest reported localities on the Pacific versant in Ecuador, and about 175 km southwest of the nearest reported locaUty (Cannatella & Duellman 1982) on the Amazonian versant of Peru (Fig. 1). Cadle collected during the periods 1 May to 25 June, 1987 and 13 to 31 January, 1989, near Monte Seco, a coiTee cooperative at 1200 m in the valley of the Rio Zana, Department of Cajamarca, Peru (Fig. 2). Although the coast and western slopes of the Peruvian Andes are generally arid and support primarily desert or dry scrub forest, local conditions sometimes permit more mesic environments, particularly in northem Peru (Koepcke 1961). The slopes north and east of Monte Seco above about 1500 m support a wet forest that receives heavy rains from January to April, and that is enveloped by dense clouds for at least the early part of the dry season (May to December). Frogs were collected near streams and waterfalls whose headwaters originate on a ridge north and east of Monte Seco. Locally, the highest mountains extend to about 3000 m elevation. Methods and Materials Using dial calipers, we measured to the nearest 0.1 mm as follows: snout-vent length (SVL), straight line from tip of head to vent; head length (HL), angle of the jaw to tip of the head; head width (HW), width of the head at the angle of the jaw; snout length (SL), anterior border of eye to tip of head; eye diameter (ED), measured in the horizontal plane; eye to nostril (EN), anterior border of eye to middle of the nostril; tympanum width (TW), measured in horizontal plane; tibia length (TL), measured with the limb ñexed; hand length (HnL), from the proximal border of the outer palmar tubercle to tip of digit III. Webbing formula notations follow Savage & Heyer (1967), as modified by Myers & Duellman (1982). In determining webbing formulae, we used the point of intersection of the web base with a 748 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON T7°0S' 77007' 7700s' '~"--:/"~'~~"" N / • Road River or stream ,,,.»''•'1 />-, \B Udima