Pristimantis bicantus Guayasamin & Funk, 2009, new species
Creators: name: Guayasamin, Juan M.
name: Funk, Chris
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Chordata
Amphibia
Anura
Strabomantidae
Pristimantis
Pristimantis bicantus

description: Pristimantis bicantus, new species
Holotype. Adult female QCAZ 19024, collected at Yanayacu Biological Station, trail to San Isidro Lakes (0°36' S, 77°53'W; 2150 m), Provincia Napo, Ecuador, on 10 January 2001 by Fernando Nogales and Diego Almeida-Reinoso.
Paratopotypes. All specimens were collected along different trails within Yanayacu Biological Station, Provincia Napo, Ecuador, or nearby the scientific station, at elevations between 2100 and 2300 m: High trail, QCAZ 19003–08, collected by Martín R. Bustamante on 2 January 2001; QCAZ 19021–23, collected by Claudia Arcanjo on 2 January 2001; QCAZ 19025–28, collected by WCF on 2 January 2001; QCAZ 39813, 39818–19, collected by Martín R. Bustamante on 3 January 2005. Macuca loma, QCAZ 18996, 18999, collected by Martín R. Bustamante and WCF on 29 December 2000; QCAZ 19044–45, 19056–57, collected by Martín R. Bustamante on 14 January 2002; QCAZ 18979, 18985–89, 18997, collected by WCF on 11 January 2001; QCAZ 18990–91, 18998, collected by WCF on 0 1 January 2001; QCAZ 18983–84, collected by WCF on 11 January 2001; QCAZ 18997–98, 19000–002, collected by Martín R. Bustamante and WCF on 0 1 January 2001. Macuca loma creek number 4, QCAZ 22379, collected by Martín R. Bustamante and Galo Diaz on 25 October 2002. San Isidro lakes, QCAZ 19017–18, collected by Fernando Nogales and Diego Almeida-Reinoso on 10 January 2001; QCAZ 39820, collected by Fernando Nogales and Diego Almeida- Reinoso on 11 January 2005. Small San Isidro lake, QCAZ 18980, 18981, collected by WCF on 10 January 2001. Trail to San Isidro lakes, QCAZ 18982, 18993, 19019–20, collected by WCF on 10 January 2001. Upper old station creek, QCAZ 19039–43, 19046–55, collected by Martín R. Bustamante on 17–18 January 2002. Upper trail, QCAZ 19030–38, collected by Martín R. Bustamante on 15 January 2002; QCAZ 22378, 22380–81, collected by Martín R. Bustamante and Galo Diaz on 15 August 2002. Waterfall trail, QCAZ 19029, collected by WCF on 5 January 2002; QCAZ 39814–17, collected by Martín R. Bustamante, Diego Almeida-Reinoso, and Fernando Nogales on 0 6 January 2005. Nearby scientific station, QCAZ 18978, collected by Diego Almeida-Reinoso and Fernando Nogales on 16 January 2001.
Generic placement. As defined by Lynch and Duellman (1997) and Hedges et al. (2008), the Pristimantis (Pristimantis) myersi group contains small frogs (adult females <28 mm), with robust bodies, short snouts, and relatively narrow heads; limbs are short to moderately long; Finger I is shorter than Finger II, and Toe V is only slightly longer than Toe III and does not extend to the proximal edge of the distal subarticular tubercle of Toe IV; the digital discs are narrow and rounded; the tympanic membrane is differentiated (except in P. leoni and P. ocreatus); cranial crests are absent; vocal slits are present (except in P. floridus); and vomerine teeth are present. The morphology of Pristimantis bicantus agrees with all the diagnostic traits of the P. myersi species group (Lynch & Duellman 1997; Hedges et al. 2008), except that the tympanic annulus is relatively larger in males than in females, and tarsal tubercles are absent.
Diagnosis. (1) Skin on dorsum shagreen with small scattered, rounded warts; upper flanks with numerous low warts; occipital and dorsolateral folds usually absent (but see variation; Figs. 1, 2); (2) tympanic membrane and tympanic annulus well differentiated (Fig. 1); tympanic annulus sexually dimorphic; tympanum in males 6.87–10.22% (x = 7.99, n = 32) SVL, tympanum in females 4.28–6.15% (x = 5.23, n = 33) SVL; (3) snout rounded in dorsal and lateral views (Figs. 1, 2); (4) upper eyelid bearing many low tubercles; upper eyelid about 43.5–85.7% (x = 70.2) IOD; cranial crests absent; (5) dentigerous processes of the vomer evident, each processes bearing 2–8 teeth; (6) males with vocal slits, nuptial pads absent; (7) Finger I shorter than Finger II; discs on Finger I and II not expanded, discs on Finger III and IV slightly expanded (Fig. 1); (8) fingers lack lateral fringes; (9) ulnar tubercles absent; (10) heel and inner and outer edges of tarsus lacking tubercles; (11) inner metatarsal tubercle oval, about 1.5–2.5 × the length of round outer metatarsal tubercle; (12) toes lack lateral fringes; webbing absent; Toe V slightly longer than Toe III; discs slightly expanded, disc on Toe IV slightly larger than those on outer fingers (Fig. 1); (13) in preservative, dorsum brown with darker markings, throat whitish cream to pale brown with two dark brown marks on center, venter whitish cream to pale brown, groin cream, posterior surfaces of thighs cream to pale brown (Fig. 2); (14) SVL in males 12.0– 15.8 mm (x = 14.2 ± 1.013, n = 32), in females 17.0– 21.7 mm (x = 19.0 ± 1.117, n = 33).
Pristimantis bicantus is distinguished from most species in the genus Pristimantis by having a Toe V slightly longer than Toe III, a Toe V that reaches about to the level of the penultimate subarticular tubercle on Toe IV, and discs on fingers and toes not expanded or slightly expanded. Pristimantis bicantus is most likely to be confused with species of the myersi group (Lynch & Duellman 1997; Hedges et al. 2008), which contains the following species: Pristimantis festae (Peracca, 1904), P. floridus (Lynch & Duellman, 1997), P. gladiator (Lynch, 1976b), P. hectus (Lynch & Burrowes, 1990), P. leoni (Lynch, 1976b), P. myersi (Goin & Cochran, 1963), P. ocreatus (Lynch, 1981), P. pyrrhomerus (Lynch, 1976b), P. repens (Lynch, 1984), P. scopaeus (Lynch, Ruiz-Carranza & Ardila-Robayo, 1996), and P. xeniolum (Lynch, 2001). The main characters distinguishing Pristimantis bicantus from P. f l o r i d u s, P. m y e r s i, and P. pyrrhomerus are the absence of tarsal tubercles (present in P. floridus, P. myersi, and P. pyrrhomerus); these species also occur in different biogreographic areas (Table 2). Additionally, Pristimantis bicantus differs from P. hectus and P. m y e r s i by lacking ulnar tubercles (present in P. hectus and P. myersi). Pristimantis bicantus is distinguished from P. leoni by lacking ulnar and tarsal tubercles (present in P. leoni), and bearing low tubercles on upper eyelid (subconical tubercles in P. leoni). Pristimantis bicantus differs from P. f e s t a e by having slightly expanded discs on outer fingers (fingers not expanded in P. f e s t a e), lacking lateral fringes on toes (present in P. f e s t a e), and having a pale cream venter in preservative (black venter usually with cream spots in P. f e s t a e). Pristimantis bicantus can be distinguished from P. ocreatus by possessing pads on fingers (pads absent on inner fingers in P. ocreatus), and having slightly expanded discs on toes and outer fingers (fingers and toes not expanded in P. ocreatus). Pristimantis bicantus differs from P. repens by lacking a single subconical tubercle on the upper eyelid (present in P. re p e n s; Lynch 1984), having, in life, a translucent venter with a gray-orange hue (olive-brown venter in P. repens; Lynch 1984); additionally, P. re p e n s is found in páramo and subpáramo habitats (Lynch 1984), whereas P. bicantus inhabits cloud forests. Pristimantis bicantus is distinguished from P. scopaeus by having an evident tympanic membrane and tympanic annulus (not visible in P. scopaeus; Lynch et al. 1996). Pristimantis bicantus is distinguished from P. xeniolum by having dentigerous process of the vomer with teeth (teeth absent in P. xeniolum; Lynch 2001), lacking ulnar and tarsal tubercles (present in P. xeniolum; Lynch 2001), and, in males, having vocal slits (absent in P. xeniolum; Lynch 2001). Finally, P. bicantus is most likely to be confused with P. g l a d i a t o r. Differences between these two species are subtle, but not overlapping. Pristimantis bicantus has teeth on the vomers (teeth absent in P. gladiator), lacks ulnar and tarsal tubercles (low tubercles present in P. g l a d i a t o r), and, in life has a gray groin with or without reddish or salmon hue (groin black with red-orange spots in P. gladiator). Additionally, P. gladiator is found at elevations between 2270 and 2910 m (Lynch 1976b; personal observation), whereas P. bicantus seems to be restricted to elevations between 2100–2300 m. Given the importance of the Andean mountains in promoting allopatric speciation (Lynch & Duellman 1997; Guayasamin et al. 2008; Bonaccorso 2009), it is relevant to note that only three species of the Pristimantis myersi group (i.e., P. bicantus, P. festae, P. gladiator) inhabit the same biogeographical region (Amazonian slope of the Andes; Table 2); therefore, comparisons between the new species and P. f e s t a e and P. g l a d i a t o r are, likely, more important when testing the validity of the new species.
Description of holotype. Adult female (QCAZ 19024, SC 408) with head narrower than widest part of body; head longer than wide (head width 91.1% head length); snout rounded in dorsal and lateral views, relatively short (snout-to-eye distance 18.6% SVL), without papilla at tip (Fig. 1); in lateral view, canthus rostralis distinct; loreal region slightly concave; nostrils slightly protuberant, directed laterally; interorbital area flat, broader than upper eyelid (upper eyelid width 69.6% interorbital distance); cranial crests absent; upper eyelid bearing several nonconical tubercles; tympanic membrane well-defined, with dark brown pigmentation on upper third; tympanic annulus distinct, round; supratympanic fold obscuring anterodorsal and posterodorsal edges of annulus (Fig. 1); tympanum diameter 47.6% eye length; two nonconical postrictal tubercles. Choanae small, nearly elliptical, not concealed by palatal shelf of maxillary; dentigerous process of the vomer oblique, widely separated, posteromedial to choanae, each bearing 3–5 small teeth; tongue slightly longer than wide, granular, without notch in posterior border.
Skin of head shagreen; dorsum shagreen, with scattered small tubercles, some of which are aligned over a W-shaped occipital mark, but not forming folds; upper flanks with numerous low warts; venter slightly areolate; discoidal fold absent; anal sheath absent. Forearm slender; radio-ulna length 24.5% SVL; ulnar tubercles absent; ulnar fold absent; hand length longer than radio-ulna length (hand length 26.1% SVL); fingers without lateral fringes; finger lengths I <II <IV <III; palmar tubercle bifid, thenar tubercle oval (Fig. 1); subarticular tubercles round, not prominent; supernumerary palmar tubercles not evident; disc cover of Finger I not expanded; those of Fingers II–IV slightly expanded; outer discs of fingers slightly narrower than Toe IV; all disc covers with nearly elliptical ventral pads defined by grooves (Fig. 1).
Hind limbs relatively robust; tibia length 54.3% SVL; foot length slightly smaller than tibia length (foot length 47.9% SVL); tarsal tubercles absent; no tubercle on heel; toes without lateral fringes (Fig. 1); subarticular tubercles round, not prominent; inner metatarsal tubercle oval, two times size of outer tubercle; supernumerary plantar tubercles not evident (Fig. 1); disc cover of Toe V not expanded, disc covers of Toes I– IV slightly expanded; toes with defined pads; disc pads nearly elliptical; toe lengths I <II <III <V <IV (Fig. 1); tip of Toe V almost reaches distal border of penultimate subarticular tubercle of Toe IV; tip of Toe III reaches proximal border of penultimate subarticular tubercle of Toe IV.
In ethanol, dorsum brown with darker interorbital bar, occipital W-shaped mark, and weakly defined chevron at the level of sacrum. Upper and lower lips with dark brown bars, supratympanic stripe dark brown. Flanks pale brown with small darker marks. Dorsum of limbs pale brown with dark brown bars. Cloacal region dark brown. Groin cream brown, anterior and posterior surfaces of thighs pale brown. Throat cream brown with darker marks on center (Fig. 2 E). Venter pale brown. Most of ventral surfaces of arms and feet dark gray. Palms and soles dark grayish brown, tubercles on palms and soles unpigmented (Fig. 2 A, E).
Measurements of holotype (mm).— Adult female (QCAZ 19024); SVL = 18.8; tibia length = 10.2; foot length = 9.0; head length = 7.9; head width = 7.2; interorbital distance = 2.3; upper eyelid width = 1.6; internarial distance = 2.4; eye-to-nostril distance = 1.8; snout-to-eye distance = 3.5; eye diameter = 2.1; tympanum diameter = 1.0; eye-to-tympanum distance = 0.9; radio-ulna length = 4.6; hand length = 4.9; and Finger-I length = 2.9.
Variation in external morphology. Meristic variation of the type series is presented in Table 4. There is conspicuous variation in the number of teeth on the dentigerous process of the vomer (2–8 teeth), usually larger individuals have more teeth. Tympanum in males larger than in females (tympanum in males 6.9– 10.2% SVL, tympanum in females 4.3–6.2% SVL). Snout with small papilla at tip (females, QCAZ 10103, 16209, 19029). Some individuals (QCAZ 16203, 16209, 19031, 19040–2, 19045, 19048, 19051, 19053, 19057) present a series of low tubercles that form low occipital and dorsolateral folds (Fig. 2).
Color in life. The following description includes the color variation found in Pristimantis bicantus. Dorsum light to dark brown usually with an indistinct dark interorbital bar and with or without dark chevron markings; some individuals with light dorsolateral line and some with pale snout; dorsal surfaces of legs with contrasting dark and light bars; distinct dark line extending from posterior edge of eye, through top half of tympanum, to above insertion of arm; flanks light brown or gray with or without diagonal dark bars extending towards groin; uniform dark brown patch with lighter colored border on posterior surface of thighs below cloacal opening; groin and hidden surfaces of thighs gray with or without a reddish or salmon hue; venter translucent with a light gray-orange hue and small white and black speckles, especially laterally and anteriorly; iris pale yellow with dark red medial horizontal bar and orange ring around pupil (Plate 3).
Color variation (in ethanol).— Dorsally, anterior half of head cream (females, QCAZ 19042, 19051; males, QCAZ 19026). Dorsum grayish cream (females, QCAZ 16201, 19039; males, QCAZ 18981, 18983– 84, 19019, 19027, 19035, 19038, 19044), pale brown (female QCAZ 19005), or uniform pale brown (female, QCAZ 19056; males, QCAZ 18994, 18997). Interorbital bar, W-shaped mark, and chevron absent (females, QCAZ 16186, 19056; males, QCAZ 18994, 18997). Dorsolateral stripes, external border of upper eyelid, and canthal stripe cream (female, QCAZ 10102, 19029, 19049, 19051; males, QCAZ 18980, 18982, 18996, 19004, 19031, 19036, 19052). Dorsolateral stripes dark gray (males, QCAZ 18994, 18997). Flanks whitish cream (females, QCAZ 16209, 19049; males, QCAZ 18981, 19030, 19032, 19035, 19038, 19044), grayish cream (female, QCAZ 19039; males, QCAZ 18980, 18983, 19052, 18984), or brown (female, QCAZ 19001). Groin and flanks brown with cream flecks (female, QCAZ 19001). Posterior surfaces of thighs creamy gray (female, QCAZ 16201; males, QCAZ 19019, 19030–02, 19035, PUCE 330, 334), or brown with cream flecks (females, PUCE 335, QCAZ 19001). Throat, venter, and groin whitish cream (females, PUCE 329, 344, QCAZ 16186, 16209, 19003, 19005–06, 19029, 19033, 19046, 19048–49; males, QCAZ 18981, 18984, 18986, 19004, 19019, 19026, 19030–02, 19038, 19044), creamy gray (females, QCAZ 16201, 19039, 19042; males, QCAZ 18980, 19052), whitish gray (females, QCAZ 19050–51), pale brown (female, QCAZ 18978), or brown (female, QCAZ 10102). Throat with no dark brown marks (females, QCAZ 10102, 19003, 19048, 19029, 19050; males, QCAZ 18992–94, 19004, 19019, 19025–26, 19030, 19036, 19038), brown with darker marks and cream flecks (males, QCAZ 18982, 18996–97, 19034), or whitish cream (male, QCAZ 18983). Venter gray (male, QCAZ 18983). Palms and soles gray (females, QCAZ 19001, 19029, 19051; male, QCAZ 19001).
Etymology. The specific name bicantus is derived from the Latin bi-, meaning “two” and cantus, meaning “song” in reference to the species’ call, which has two distinct call types.
Distribution. Pristimantis bicantus is known only from the cloud forests surrounding Yanayacu Biological Station (0°36΄S, 77°53΄W) at elevations between 2100 and 2300 m (Fig. 3).
Ecology. Pristimantis bicantus is one of the two most abundant frog species at Yanayacu (Pristimantis cf. petersi is the other most abundant frog; Table 1). Ninety-four individuals were found at night during approximately two years of inventory work (2000–2002), of which 65 were adults, 23 were juveniles, one was a subadult, and stage was not determined for the remaining five. Most were found in primary forest, although 31% were found in secondary forest, suggesting this species is more tolerant of disturbance than most other Pristimantis at Yanayacu. Pristimantis bicantus used low leaves 0–80 cm (x = 32 cm) above the ground as substrate at night (Fig. 4). Of the eight P. bicantus females dissected to count and measure ovarian ova, the number of large ova was 13–20 (x = 16.3), each with a diameter of 1.1–2.6 mm (x = 2.1 mm). Some females also had a few to several very small ova.
Museum number
mean, standard deviation, and sampling size (n).
Females Males
SVL 17.0–21.7 11.8–15.8 18.9 ± 1.1 14.2 ± 1.0 n = 36 n = 32
Foot 8.0–9.5 5.5–6.8 8.7 ± 0.3 6.4 ± 0.4 n = 26 n = 12
Head length 7.2–8.6 5.1–6.5 8 ± 0.3 6.0 ± 0.4 n = 26 n = 12
Head width 6.2–7.8 5.0–6.2 7.2 ± 0.3 5.3 ± 0.3 n = 26 n = 12
Interorbital distance 2.0–2.6 1.7–2.2 2.3 ± 0.1 1.9 ± 0.1 n = 36 n = 32
Upper eyelid width 1.0–1.9 1.0–1.7 1.6 ± 0.2 1.3 ± 0.2 n = 36 n = 32
Eye-to-nostril distance 1.5–2.2 1.3–1.7 1.9 ± 0.1 1.4 ± 0.1 n = 26 n = 12
Snout-to-eye distance 3.0–3.9 2.2–2.9 3.3 ± 0.2 2.5 ± 0.2 n = 26 n = 12
Eye diameter 2.1–2.8 1.7–2.5 2.4 ± 0.2 2.0 ± 0.3 n = 26 n = 12
Tympanum 0.8–1.4 0.9–1.5 1 ± 0.2 1.2 ± 0.2 n = 36 n = 32
Radioulna length 4.4–5.3 2.9–3.9 4.8 ± 0.2 3.6 ± 0.3 n = 26 n = 12
Hand length 4.3–5.1 3.0–3.9 4.8 ± 0.2 3.5 ± 0.3 n = 26 n = 12
Finger I length 2.4–3.0 1.6–2.0 2.7 ± 0.1 1.9 ± 0.1 n = 26 n = 12
Finger II length 2.7–3.6 1.9–2.5 3.2 ± 0.2 2.3 ± 0.2 n = 26 n = 12
Vo c al iz a ti on. We recorded the calls of two Pristimantis bicantus males at Yanayacu Biological Station on 11 January 2001 (see Table 3 for details). Two call types were recorded, short calls and long calls (Fig. 5). Males often produced call series consisting of a few to several short calls followed by many long calls. Short calls were also heard without long calls, but long calls were always preceded by short calls as part of a call series. Short calls consisted of 1–3 pulses with a mean fundamental frequency of 3134–3186 Hz. Long calls consisted of a mean of 15.5–18.9 more rapid pulses and a slightly lower mean fundamental frequency of 2831–2973 Hz. The fundamental frequency was equivalent to the dominant frequency for both short and long calls. The long calls sound like a fingernail being dragged across the teeth of a comb. Some call series were exceptionally long, lasting up to 43.1 s. Theses calls are likely advertisement calls since the males recorded were part of a large breeding chorus of P. bicantus.
Remarks. In Funk et al. (2003), Pristimantis bicantus was referred to as Eleutherodactylus sp. 3.
description: Published as part of Guayasamin, Juan M. & Funk, Chris, 2009, The amphibian community at Yanayacu Biological Station, Ecuador, with a comparison of vertical microhabitat use among Pristimantis species and the description of a new species of the Pristimantis myersi group, pp. 41-66 in Zootaxa 2220 on pages 49-56, DOI: 10.5281/zenodo.190060