Pristimantis dendrobatoides, Means, Bruce & Savage, Jay M., 2007

Means, Bruce & Savage, Jay M., 2007, Three New Malodorous Rainfrogs of the Genus Pristimantis (Anura: Brachycephalidae) from the Wokomung Massif in west-central Guyana, South America, Zootaxa 1658, pp. 39-55 : 40-45

Pristimantis dendrobatoides new species.

( Figs. 1 , 2 , 3 .)

Mimic Rainfrog

Holotype. USNM 563662, an adult male from the Wokomung Massif, near Falls Camp, Potaro-Siparuni District, west-central Guyana; 05° 05’ 25” N, 59° 50’ 18” W, 1385 m; collected 2 hours after dark at 8: 30 p. m. on 28 July 2003 by D. B. Means (field collection DBM-3152; CPI 10181).

Paratopotype. USNM 563661, a juvenile female collected 3 hours after dark at 9: 30 p. m. on 22 July 2003 by D. B. Means (field collection DBM-3152; CPI 10180).

Other paratypes. ROM 43317, a female from N slope of Mt. Wokomung, Potaro-Siparuni District, westcentral Guyana; 05° 05’ 33” N, 59° 50’ 35” W, 1411 m; collected 3–5 November 2004 by R. MacCulloch, A. Lathrop, and S. Khan. USNM 564161-564162, two adults from the Potaro-Siparuni District, west-central Guyana; 05° 00’ 08” N, 59° 52’ 47” W, ca. 1540 m; collected 7 December 2006 by D. B. Means (field collection DBM-3372; CPI 10353 & 10354). USNM 564163, an adult from cloud forest near the top of Mt. Kopinang, SE part of the Wokomung Massif, ca. 500 m W of Kamana Falls, Potaro-Siparuni District, west-central Guyana; ca. 05° 00’ 08” N, 59° 52’ 47” W, ca. 1570 m; collected 10 December 2006 by D. B. Means & M. Kalamandeen (field collection DBM-3376, CPI 10355). USNM 564164, an adult from Guyana, Potaro- Siparuni District, cloud forest at top of Kamana Falls on Mt. Kopinang, SE part of the Wokomung Massif; 05° 00’ 08” N, 59° 52’ 47” W, ca. 1570 m; collected 10 December 2006 by D. B. Means and M. Kalamandeen (field collection DBM-3377, CPI 10356).

Diagnosis. A small species (SL 28.5–31.0 mm), unassignable to any of the species groups of Pristimantis recognized by Lynch and Duellman (1997) or Savage (2002). It resembles members of the Pristimantis unistrigatus group (about 250 recognized species) in having Finger I shorter than Finger II, a coarsely areolate venter and narrow head (37–42% of SL). However, unlike members of that group, the tip of Toe V reaches 1/ 3 the distance between the penultimate and distal subarticular tubercles when adpressed to IV and that of Toe III when adpressed to Toe IV reaches to the distal margin of the penultimate subarticular tubercle on Toe IV. In the unistrigatus group Toe V is relatively much longer and reaches to the distal subarticular tubercle on Toe IV and Toe III reaches to the midpoint of the penultimate subarticular tubercle on Toe IV when adpressed to that toe. The new form is further distinctive in the combination of the following features: dorsum verrucose, tympanum distinct, toes without webs, dorsum purplish black with several large red spots, and venter and undersurfaces of limbs bright red in life ( Fig. 1 ).

Myers and Donnelly (1996, 1997) described two species from highlands in Venezuela, Pristimantis pruinatus of Cerro Yavi (a tepui) at 2150 m and P. cavernibardus of Pico Tamacuari at 1160–1200 m, that also have a relatively short Toe V that is longer than Toe III. Pristimantis dendrobatoides most obviously differs from P. pruinatus in having truncate finger and toe discs with those on the outer fingers much larger than those on the toes versus round finger discs that are smaller than the round toe discs in the latter. Pristimantis cavernibardus has deeply emarginate finger discs while those of the new form are even or at the most retuse. Neither of the Myers and Donnelly species have red dorsal spotting or the ventral surfaces red in life.

Etymology. The name dendrobatoides refers to the general resemblance of these frogs to toxic members of the genus Dendrobates (Greek dendron = tree + bates = one who walks) and Greek oides = resembling. That the new species is malodorous and likely has noxious or toxic skin secretions (see Discussion) adds weight to the selection of this name.

General characteristics. Head relatively narrow; HW/HL = 87–97%; snout subovoid in dorsal outline, snout profile round. Canthus rostralis slightly concave. Loreal region concave, upper lip not flared in crosssection; postrictal area with a glandular swelling. Choanae elliptical, not concealed by maxillary arch, larger than oblique and widely separated vomerine tooth patches, lying posterior but internal to choanae; ostia pharyngea present. No vocal slits or sac. Surface of head, upper eyelid, dorsum, and flanks covered with large smooth, glandular tubercles. EW/IOD = 88–110%. Tympanum distinct, annulus tympanicus prominent, slightly obscured by skin dorsally, width slightly less than horizontal diameter of eye; TY/E = 57% in male, 53% in female; no definite supra- or post-tympanic fold. Upper surfaces of arm and thigh smooth; upper surfaces of crus granular, those of lower limb and foot smooth. Finger II much longer than Finger I when adpressed together; relative finger lengths III>IV>II>I. No nuptial pads. Disc cover on Finger I small, slightly wider than finger. Disc covers on Fingers II to IV truncate, at least one slightly retuse. Discs on Fingers III–IV about equal in size, larger than disc on Toe II; width of disc on Finger III equal to horizontal width of tympanum; disc pads broadened on all fingers. No fringes, ridges, or webbings on fingers. Subarticular tubercles under fingers and toes round, even to globular in profile; no supernumerary tubercles; thenar tubercle low and elongate; palmar tubercle cordate; five or six accessory palmar tubercles. Ulnar margin smooth, no tubercles or fold. Heel tubercular like upper thigh surface. Toe discs much smaller than finger discs; disc on Toe IV largest, smaller than disc on Finger II; disc covers truncate, even; disc pads broadened. Relative toe lengths IV>V>III>II>I; Toe V longer than Toe III when adpressed against Toe IV, reaching 1/3 the distance between penultimate and distal subarticular tubercles; Toe III reaching to midpoint of penultimate subarticular tubercle when adpressed to Toe IV. No fringes, ridges or webbings on toes. No supernumerary tubercles under toes; plantar surface smooth; inner metatarsal tubercle large, elongate; outer metatarsal tubercle tiny, round; no tarsal fold or tubercle ( Fig. 2 ). No inguinal gland; venter coarsely areolate; throat and under surfaces of limbs smooth. Legs relatively short, heels slightly overlapping when legs folded at right angles to sagittal plane. C/ SL 57–67%. See Table 1 for summary statistics.

Coloration in life. Upper surfaces of head and body dark purple; head uniformly dark purple except for one or two small interorbital bright red spots and three or four bright red lip spots present in USNM 563661 but absent in the holotype (USNM 563662); one distinct, bright red, round middorsal, suprascapular spot on all seven specimens with 0–4 smaller, round, middorsal, suprasacral spots; upper arm bright red or dark purple with several bright red spots; posterior of thigh bright red; lower arm and dorsal surface of hands, feet, and toes dark purple with bright red spots, more prominent distally; hand red, finger discs purple; upper leg surface purple with small red spots; three obscure reddish cross bands on crus; toe discs outlined by purple. Undersurface of the skin over each dentary dark purple with four discrete, red spots; throat dark purple to black, extending onto the anterior pectoral area as a small bib. Venter below the bib uniformly bright red or, in some individuals, marked with a faint, irregular, mid-ventral suffusion of black pigment from bib to hind limb insertions; in some of these, a faint black wash over red is present lateral to the mid-ventral darker pigment (the mid-ventral and lateral dark wash becoming much more pronounced in preservative); underside of legs sprinkled with tiny dark punctations, most heavily on crus; palmar and plantar surfaces dark purple. Iris black with faint reddish punctations, but thin and continuously outlining the edge of the pupil. No color changes were noted between day and night. Specimens found with dry skin ( Fig. 1 a) had a blue-gray cast to their dorsal skin as opposed to wet frogs ( Fig 1 .b).

Coloration in preservative. Depending on the type of preservative and length of time in it, the dark purple changes to brown and the bright red color becomes dull white. Upper surfaces of head and body dark brown; head uniform brown laterally except for three or four light lip spots; large, light, round, middorsal suprascapular spots; upper arm lighter brown with light spots; hand light, finger discs brown; upper leg surface brown with small light spots; two or three light cross bands on top of crus; toe discs outlined by dark. Lower lip dark brown with four large light spots; throat/anterior pectoral area black; venter cream with sprinkling of tiny dark punctations or marked with irregular black midventral stripe and in some individuals black lateral marbling present lateral to stripe; underside of legs suffused with dark punctations, most heavily on crus; palmar and plantar surfaces dark brown.

Measurements of holotype (in mm). SL 29.6; HL 12.2; HW 10.9; EW 2.9; IOD 3.0; E 5.5; TY 2.4; C 17.5; FL 14.5.

Habitat and habits. USNM 563661 and 563662 were each found sitting on leaves of shrubs ( Melastomataceae ) about two meters off the ground in cloud forest understory vegetation in the gully created by a small, cascading mountain stream. Both were taken two to three hours after dark in heavy rains. USNM 564161-564164 (CPI 10353 to 10356) were also collected sitting on small leaves from 0.5–1.5 m off the ground in cloud forest densely draped with moss and other epiphytes; these frogs were up to 40 m from any stream. All specimens were collected as lone individuals 2–4 hours after full dark. This species did not become active until later in the night. Some were caught during a hard rain, others during lulls in rainfall. In every case, the frogs were sitting on small leaves, often not much wider than their bodies. When grasped, a pungent odor was detected from the collector’s hand and frog’s skin. The dorsal skin was gingerly tasted and found to be bitter. The front of the researcher’s tongue lost the bad taste shortly following expectoration, but the back of the tongue became slightly numb for about five minutes.

Distribution. Known only from the Wokomung Massif in west-central Guyana ( Fig. 3 ) in cloud forest habitat (1385–1570 m).

Figures

FIGURE 1. Pristimantis dendrobatoides new species; a = USNM 563662, holotype, at moment of discovery on the leaf of a melastome; b = USNM 563661, paratopotype, side view; c = USNM 563661, dorsal view; d = USNM 563661, ventral view.

FIGURE 2. Hand (left) and foot (right) of Pristimantis dendrobatoides new species, USNM 533652 holotype. Black bars = 5.0 mm.

FIGURE 3. Map of Guyana with the location of the Wokomung Massif in the Pakaraima Mountains (gray shading) and in relation to some other teuis in Guyana. Map modified from one supplied by Philippe J. R. Kok.

Tables

TABLE 1. Measurements (in mm) and proportions of adult Pristimantis dendrobatoides, P. j e s t e r, and P. saltissimus; ranges followed by means and one standard deviation in parentheses. For abbreviations, see Methods.

Species: dendrobatoides (n=7)	jester (n=5)	saltissimus (n=15)
SL 28.1–32.2	19.4–22.8	16–27.1
(29.5 ± 1.33)	(21.2 ± 1.29)	(22.5 ± 3.63)
HL 11.1–12.9	9.0–9.7	7.5–11.8
(11.9 ± 0.61)	(9.4 ± 0.26)	(9.7 ± 1.51)
HW 10.2–11.5	8.0–8.7	6.2–10.8
(10.8 ± 0.49)	(8.4 ± 0.26)	(8.6 ± 1.23)
EW 2.9–3.3	2.2–3.1	1.6–3.3
(3.03 ± 0.15)	(2.8 ± 0.35)	(2.5 ± 0.52)
IOD 2.8–3.3	1.8–2.3	2.1–3.2
(3.0 ± 0.19)	(2.3 ± 0.32)	(2.5 ± 0.32)
E 4.8–5.5	4.2–4.7	3.2–5.1
(5.2 ± 0.28)	(4.5 ± 0.23)	(4.2 ± 0.60)
TY 2.2–2.6	0–0	0.7–1.6
(2.4 ± 0.15)	0	(1.1 ± 0.29)
C 16.7–18.7	11.4–12.6	10.2–15.9
(17.6 ± 0.79)	(11.9 ± 0.43)	(12.9 ± 2.01)
FL 13.4–15.0	9.7–10.9	6.4–12.8
(14.3 ± 0.61)	(10.2 ± 0.50)	(10.2 ± 1.77)
HL/SL 0.37–0.42	0.42–0.48	0.40–0.47
HW/SL 0.36–0.37	0.37–0.40	0.35–0.44
HW/HL 0.87–0.97	0.86–0.92	0.83–1.06
C/SL 0.57–0.67	0.52–0.61	0.53–0.64
EW/IOD 0.88–1.10	1.08–1.30	0.73–1.50
TY/E 0.40–0.54	0	0.21–0.37