Pristimantis orcus, Lehr, Edgar, Catenazzi, Alessandro & Rodríguez, Daniel, 2009

Lehr, Edgar, Catenazzi, Alessandro & Rodríguez, Daniel, 2009, A new species of Pristimantis (Anura: Strabomantidae) from the Amazonian lowlands of northern Peru (Region Loreto and San Martín), Zootaxa 1990, pp. 30-40 : 31-39

Pristimantis orcus new species

Eleutherodactylus sp. 5, Fig. 7A - Catenazzi and Bustamante (2007) Amphibians and reptiles; Appendix 4. pp. 130–134, 206–211. In: Vriesendorp, C., J. A. Álvarez, N. Barbagelata, W. S. Anderson & D. K. Moskovits (Eds.). Nanay-Mazán-Arabela. Rapid Biological Inventories 18. The Field Museum, Chicago.

Holotype: MUSM 27435 ( Figs. 1 A–C; 2–3), an adult female collected at Comunidad de Nueva Vida (3º 37' 57.2'' S, 75º 20' 48.9'' W) at 158 m elevation, Distrito de Trompeteros, Provincia de Loreto, Región Loreto, Peru, on 18 June 2008 by D. Rodríguez.

Paratypes: Six: four males ( MUSM 22437, 25938, 27436, 27392), and two females ( MUSM 22444, 27456). One male ( MUSM 27436) collected in axillar amplexus with the holotype; one male ( MUSM 27392) collected at 3º 40' 48.3'' S, 75º 34' 58.6'' W at 163 m elevation, Distrito de Trompeteros, Provincia de Loreto, on 0 3 April 2008 by D. Rodríguez; one female ( MUSM 27456) collected at Comunidad de Santa Rosa de Siamba (4º 06' 17.3'' S, 75º 32' 00.4'' W) at 133 m elevation, Distrito de Urarinas, Provincia de Loreto, on 20 March 2008 by J. Ramírez; one male ( MUSM 25938) collected at the upper Panguana watershed (an affluent of the Río Napo; 2º 08' 11'' S, 75º 08' 57'' W) at 160 m elevation, Distrito de Napo, Provincia de Maynas, on 29 August 2006 by A. Catenazzi and M. Bustamante. All from Región Loreto, Peru. One male ( MUSM 22437) and one female ( MUSM 22444) collected at km 34 on road from Tarapoto to Yurimaguas (6º 25' 38.6'' S, 76º 18' 00.7'' W), Valle de Cainarachi, Distrito de La Banda de Shilcayo, Provincia de San Martín, Región de San Martín, Peru, on February 2005 by C. Torres.

Diagnosis. A member of Pristimantis based on the diagnostic set of characters as defined by Hedges et al. (2008) assigned to the Pristimantis (Pristimantis) unistrigatus species Group having the following combination of characters: (1) Skin on dorsum finely shagreen with low scattered tubercles, skin on venter weakly areolate; discoidal fold present; dorsolateral fold absent; (2) tympanic membrane and tympanic annulus present; (3) snout acutely rounded in dorsal view, rounded in lateral view; (4) upper eyelid with minute tubercles; width of upper eyelid narrower than IOD; cranial crests absent; (5) dentigerous processes of vomers prominent, oblique; (6) males without vocal slits, nuptial pads present on dorsal and medial surfaces of thumb; (7) Finger I shorter than Finger II; discs of digits broadly expanded, truncate; (8) fingers with broad lateral fringes; (9) ulnar and tarsal tubercles present; (10) heel with small tubercles; inner tarsal fold present; (11) inner metatarsal tubercle ovoid, about three times as large as outer; outer metatarsal tubercle rounded; supernumerary plantar tubercles present; (12) toes with broad lateral fringes; webbing between Toes II–V; Toe V much longer than Toe III; discs of digits broadly expanded, truncate, about as large as those on fingers; (13) in ethanol, dorsum grayish brown with tan blotches, venter grayish brown and tan mottled; (14) SVL in adult females 32.6–36.5 mm (n = 3), in adult males 20.0– 25.1 mm (n = 4).

Pristimantis orcus is most similar to following five medium-sized species of Pristimantis from the Amazonian lowlands and lower eastern Andes ( altamazonicus , diadematus , eurydactylus , ventrimarmoratus , and Pristimantis sp.) in having Finger I <II, discs on fingers and toes broadly extended, dorsolateral folds absent, dentigerous processes of vomers, males without vocal slits, a pale venter with darker blotches, and the groin with a contrasting pattern consisting of white, blueish white, red or yellow with dark brown or black ( Table 1 ). Pristimantis orcus differs from all by its unique coloration pattern consisting of black with white or whitish blue blotches in axilla, groin, anterior and posterior surfaces of the thighs and concealed surfaces of the tibia and by its broad lateral fringes on fingers and toes. Furthermore, the new species differs from P. altamazonicus and P. ventrimarmoratus by having a distinct tympanic annulus and membrane, which are absent in the latter two species. Pristimantis orcus differs from Pristimantis sp. (currently being described by Lehr & von May, in press) in having a tympanic membrane and males with nuptial pads, both characters are absent in Pristimantis sp. Pristimantis orcus differs from P. diadematus in having the venter weakly areolate (smooth in P. diadematus ) and by being smaller. Pristimantis orcus differs from P. eurydactylus in having a shagreen dorsum with minute scattered tubercles (tuberculate in P. eurydactylus ) and by being smaller. Table 1 presents a detailed comparison between Pristimantis orcus and the above-mentioned species.

Four other species of Pristimantis ( carvalhoi , croceoinguinis , imitatrix , and martiae ) are widely distributed in the Amazonian lowlands, but can be easily distinguished from P. o rc u s in lacking a tympanic annulus and tympanic membrane (present in P. o rc u s) and males lacking nuptial pads (present). Furthermore Pristimantis carvalhoi has the dorsum with conical tubercles (absent), fingers and toes without lateral fringes (present), and in life the groin yellow (black with white blueish blotches), and the venter creamy tan (dark brown and tan mottled). Pristimantis croceoinguinis lacks lateral fringes on fingers and toes (present in P. orcus ), and has in life a yellow to orange spot in the groin (black with white blueish blotches), and the venter gray with white flecks (dark brown and tan mottled). Pristimantis imitatrix lacks dentigerous processes of vomers (present), has in life the groin mottled black and white (black with white blueish blotches), and the venter pale blueish gray with dark brown or black flecks or reticulations (dark brown and tan mottled), and is much smaller (SVL to 20.2 mm in P. imitatrix [ Duellman 1978b] vs. SVL to 36.5 mm in P. o rc u s). Pristimantis martiae has fingers and toes with narrow lateral fringes (broad), and in life the venter grayish brown with small white to pale orange flecks (black with white blueish blotches). Three other species of Pristimantis ( ockendeni , toftae , and variabilis ) from the Amazonian lowlands share with P. o rc u s a tympanic annulus and tympanic membrane, but males of these species lack nuptial pads (present). Furthermore Pristimantis ockendeni usually has dorsolateral folds (absent), fingers and toes with narrow lateral fringes (broad), and the scapular with a H- or W-shaped fold (absent). Pristimantis toftae has the upper lip with a white margin (absent), in life the groin bears a yellow to orange spot (black with white blueish blotches), and the venter is pale cream (dark brown and tan mottled). Pristimantis variabilis lacks lateral fringes on fingers and toes (present), has in life the groin with a yellow fleck bordered with black (black with white blueish blotches), and the venter cream with brown or gray flecks (dark brown and tan mottled).

Pristimantis from the Amazonian Lowlands.

Description of the holotype. Head narrower than body, slightly longer than wide; head width 37.0% of SVL; head length 38.6% of SVL; snout moderate, acutely rounded in dorsal view, rounded in lateral view, ( Figs. 3 A, B), eye–nostril distance larger than eye diameter; nostrils protuberant, directed dorsolaterally; canthus rostralis slightly concave in dorsal view, rounded in profile; loreal region slightly concave; lips flared; upper eyelid with minute tubercles; width of upper eyelid narrower than IOD (upper eyelid width 86.8% of IOD); supratympanic fold short, broad, concealing posterior margin of tympanum; tympanic membrane and tympanic annulus present, prominent, about half the size of ED (54.3%), separated from eye by half its diameter; postrictal tubercles absent. Choanae large, ovoid, not concealed by palatal shelf of maxilla; dentigerous processes of vomers prominent, oblique; tongue two times as long as wide, posteriorly notched, posterior one half free.

Skin on dorsum shagreen with scattered tubercles more dense on head, dorsolateral folds absent; skin on flanks areolate; skin on throat, chest, and belly weakly areolate; weak discoidal fold present, more prominent posteriorly; cloacal sheath short; large tubercles absent in cloacal region. Outer surface of ulnar with minute tubercles; palmar tubercles low, outer palmar tubercle bifid, ovoid, approximately three times the size of elongate, inner palmar tubercle; one low supernumerary tubercle at base of each finger, about half the size of subarticular tubercles; subarticular tubercles well defined, ovoid in dorsal view, conical in lateral view; fingers with lateral fringes broadest on base of fingers; Finger I shorter than Finger II; discs on digits of outer fingers broadly expanded, about twice the size of digit proximal to it on Fingers III and IV, truncate ( Fig. 3 C).

Hind limbs relatively short, tibia length 44.1% of SVL; foot length 41.4% of SVL; upper surface of hind limbs shagreen with small, scattered tubercles; posterior and ventral surfaces of thighs weakly areolate; heel with minute tubercles and one slightly larger conical tubercle in its middle; outer surface of tarsus with minute tubercles; tarsal fold long, distinct, not contacting inner metatarsal tubercle, metatarsal tubercles low, inner metatarsal tubercle ovoid, about four times as large as elongate outer metatarsal tubercle; one plantar supernumerary tubercle on basis of each toe, about one third the size of subarticular tubercles; subarticular tubercles well defined, less prominent than those on fingers, ovoid in dorsal view, slightly conical in profile; toes with broad and thin lateral fringes, concealing sides of toes, basal webbing present between Toes II–V; discs on digits of toes broadly expanded, about twice the size of digit proximal to it on Toes IV and V, about as large as those on fingers, truncate; relative lengths of toes: 1 <2 <3 <5 <4; Toe V much longer than Toe III ( Fig. 3 D).

Measurements (in mm) of holotype: SVL 36.5; tibia length 16.1; foot length 15.1; head length 14.1; head width 13.5; eye diameter 3.5; tympanum diameter 1.9; interorbital distance 3.8; upper eyelid width 3.3; internarial distance 3.0; eye–nostril distance 4.7.

Coloration of holotype in preservative ( Fig. 2 ): Dorsum grayish brown with irregularly shaped tan blotches on region between interorbital area to cloaca; each lower arm with one dark brown blotch; hind limbs grayish brown without bars, heels tan; Fingers I and II gray, Fingers III and IV grayish brown, toes grayish brown; head laterally grayish brown without canthal and sypratympanic stripes and without blotches on upper lip; upper half of tympanum grayish brown, lower half tan; flanks paler than dorsum, tan and brown mottled; axilla, groin, and anterior and posterior surfaces of thighs and concealed surfaces of tibia black with white blotches; throat, chest, and belly dark brown and tan mottled; thighs grayish brown with few tan flecks; hands and feet gray; iris dark gray.

Coloration of holotype in life ( Figs. 1 A–C): As described above except for white being whitish blue and for iris gold with cupper tint and fine black reticulations.

Variation. In respect to morphology and coloration the paratypes are similar to the holotype. Male specimens are smaller than females, lack vocal slits, and have tan nuptial pads on dorsal and medial surfaces of thumb. The ventral coloration tends to be paler in males than in females. In life one male (MUSM 25938, Figs. 1 D–F) is dorsally brown with tan and olive green blotches, axilla, groin, anterior surface of thighs, concealed surfaces of tibia and tarsus are black with whitish blue blotches, the iris is pale brown with dark brown reticulations and a dark brown vertical streak from pupil to lower half of iris. In life, the iris of one male (MUSM 27436) is pale brown with fine black reticulations with a black vertical streak through the pupil giving a cross-like appearance. See Tables 2 and 3 for measurements and proportions of the type series.

Distribution and ecology. Pristimantis orcus is known from three localities in Región Loreto and from one locality in San Martín ( Fig. 4 ). All specimens were found at night on the ground in primary (MUSM 27456) and secondary forests (MUSM 27435–36, 27392). For description of the collecting site of one specimen (MUSM 25938) from near the Panguana stream in northern Loreto see Vriesdendorp et al. (2007).

Etymology. The specific name orcus is the Latin noun for underworld. The specific name is a noun in apposition and refers to the contrasting pattern of black and white in axilla, groin, anterior and posterior surfaces of thighs and concealed surfaces of tibia of preserved specimens, which remind us of the pattern in Orcas ( Delphinidae ).

Pristimantis orcus

Remarks. Because of its distribution in northern Peru relatively close to the borders of Ecuador and Colombia, Pristimantis orcus is very likely distributed in these countries as well.

Several species of Pristimantis from the Amazonian lowlands have the belly, groin, anterior surface of thighs, and concealed surfaces of tibia with a contrasting coloration pattern of black and white ( Table 1 ).

Currently all these species are assigned to the unistrigatus Group which is the largest species group ( Lynch & Duellman 1997) and known to be paraphyletic ( Hedges et al. 2008). Most members of the unistrigatus Group were assigned to it because their morphological character set did not seem to fit into one of the other species groups of Pristimantis . Because of the morphological similarities among Pristimantis altamazonicus , P. diadematus , P. eurydactylus , P. orcus , P. ventrimarmoratus , and Pristimantis sp., we assume that they share a close phylogenetic history and might be part of a distinct clade. Before assigning them to a new species group, the results of phylogenetic analyses currently being undertaken by different research groups should be awaited.

Figures

FIGURE 1. Left column: Female Pristimantis orcus (MUSM 27435, holotype, SVL 36.5 mm) in dorsolateral (A), lateral (B), and ventral (C) views; right column: male Pristimantis orcus (MUSM 25938, paratype, SVL 22.4 mm) in dorsolateral (D), lateral (E), and ventral (F) views. Photos A – C by D. Rodríguez, photos D – F by A. Catenazzi.

FIGURE 2. Preserved Pristimantis orcus (holotype) in dorsal (A), and ventral (B) views. Photos by E. Lehr.

FIGURE 3. Dorsal (A) and lateral (B) views of head and ventral views of hand (C) and foot (D) of Pristimantis orcus (MUSM 27435). Scale bar = 5 mm. Drawings by E. Lehr.

FIGURE 4. Map illustrating collecting sites (indicated by circles) and type locality (indicated by a star) of the type series of Pristimantis orcus in northern Peru.

Tables

TABLE 1. Selected characters (+ = character present; — = character absent) and character conditions among selected

Characters and source	orcus This paper	altamazonicus (Lynch 1980)	diadematus (Lynch 1980)	eurydactylus (Hedges & Schlüter 1992; Lehr and von May, in press)	ventrimarmoratus (Lynch & Duellman 1980)	species (Lehr & von May, in press)
SVL (mm)	20.0–25.1	14.4–23.1	20.0–27.4	18.2–31.8	17.8–25.5	22.8–24.4
Dorsal skin	finely shagreen with scattered minute tubercles	shagreen	shagreen	tuberculate	shagreen	shagreen with scattered minute tubercles
Ventral skin	weakly areolate	coarsely areolate	smooth	weakly areolate	coarsely areolate	areolate
Tympanic annulus	+, prominent	—	+, prominent	+, prominent	—	+
Tympanic membrane	+, prominent	—	+, prominent	+, prominent	—	—
Nuptial pads	+	+	+	+	+	—
Lateral fringes on toes and fingers	+, broad	—	+, narrow	+, narrow	+, narrow	+, narrow
Toe webbing	+	—	—	—	+	+
Life coloration on chest and belly	dark brown and tan mottled	gray or grayish brown, with or without small white flecks	creamy white with a greenish tint posteriorly	in ethanol: venter is white with or without brown flecks or small spots	white with bold black mottling	dark gray with white mottling
Groin coloration	white or whitish blue and black	red or salmon and black	bluish white, yellowish tan, pink, or pale green with diagonal dark brown bars	in ethanol: tan and brown	creamy white with brown marks	yellow and black