Pristimantis bambu Arteaga-Navarro & Guayasamin

Arteaga-Navarro, Alejandro F. & Guayasamin, Juan M., 2011, A new frog of the genus Pristimantis (Amphibia: Strabomantidae) from the high Andes of Southeastern Ecuador, discovered using morphological and molecular data, Zootaxa 2876, pp. 17-29 : 19-27

publication ID	https://doi.org/ 10.5281/zenodo.205032
DOI	https://doi.org/10.5281/zenodo.5624768
persistent identifier	https://treatment.plazi.org/id/03B28796-FFCD-FFE7-19B2-3D1CFBBC4817
treatment provided by	Plazi
scientific name	Pristimantis bambu Arteaga-Navarro & Guayasamin
status	sp. nov.

Treatment

Pristimantis bambu Arteaga-Navarro & Guayasamin , new species

Holotype. QCAZ 46740, an adult male ( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ) obtained by Alejandro F. Arteaga-Navarro on January 0 7, 2010, at La Libertad, Reserva Mazar (02.54804 S, 78.69741 W; 2976 m.a.s.l.), Cantón Azogues, Provincia Cañar, Ecuador; airline distance from Rivera is 6.6 km.

Paratypes. All 24 paratypes ( Figs. 4 View FIGURE 4 A, B) were collected by Alejandro F. Arteaga-Navarro on January and March 2010 at the Reserva Mazar, southern Sangay National Park, east of Pallcayacu river, within the Cantón Azogues, Provincia Cañar, Ecuador. From these, 16 are adult males ( QCAZ 46704, 46706–7, 46710–12, 46724– 27, 46741–42, 47555, 47558, 47556–57); 6 are adult females ( QCAZ 46705, 46708, 46739, 46743–44, 7559); and 2 are juvenile females ( QCAZ 46713–14).

Diagnosis. The new species is placed in the genus Pristimatis, as diagnosed by Hedges et al. (2008), because of the presence of the following traits: cranial crests absent, dentigerous process of the vomers present, and Tshaped terminal phalanges. Pristimantis bambu is diagnosed by having: (1) skin texture of dorsum shagreen with few widely interspersed low tubercles; middorsal fold barely noticeable and fragmented when present ( Fig. 1 View FIGURE 1 A); dorsolateral folds ill-defined and incomplete, sometimes absent; venter areolate, lacking discoidal or thoracic folds ( Fig. 1 View FIGURE 1 B); (2) tympanic membrane absent; tympanic annulus present, 40–71% of eye length in females and 42– 65% in males, with upper rim obscured by supratympanic fold; (3) snout short, acuminate in dorsal view and rounded in profile; (4) upper eyelid lacking enlarged tubercles; when present, tubercles are low and almost undistinguishable from surrounding skin texture; upper eyelid width 49–83% of interorbital distance; cranial crests absent; (5) dentigerous process of vomers well developed, oblique in outline, positioned posterior to level of choanae and separated medially by distance less than width of odontophore, each process bearing 4–10 teeth; (6) males with a small subgular vocal sac; vocal slits present; nuptial pads absent; (7) first finger shorter than the second; discs on fingers expanded and rounded to slightly truncated ( Fig. 2 View FIGURE 2 A), except for Finger I that is only barely expanded; (8) fingers bearing narrow lateral fringes; outer palmar tubercle divided at least distally, inner portion larger and elliptical and outer portion smaller and round; supernumerary tubercles round ( Fig. 2 View FIGURE 2 A); (9) ulnar tubercles coalesced into fold; (10) no heel or tarsal tubercles; (11) toes bearing narrow fringes; webbing absent; Toe V slightly longer than Toe III; toe discs expanded, rounded to slightly truncated ( Fig. 2 View FIGURE 2 B); (12) inner metatarsal tubercle elliptical, about 1.2–2 times the size of outer, rounded and enlarged metatarsal tubercle; supernumerary plantar tubercles round and weakly developed ( Fig. 2 View FIGURE 2 B); (13) in ethanol, dorsum pale brownish gray in males (blackish or slate gray in females), with minute dark spots on the scapular and sacral region ( Fig. 3 View FIGURE 3 ), and faint barring on the dorsal surfaces of limbs (absent in females); dark postocular stripe and faint supralabial bars present; flanks with some localized rusty tinge on the axilla, groin and hidden surfaces of hind limbs; pale cream spots enclosed by blackish pigment may be present on the groin and posterior surfaces of the thigh (bolder and invariably present in females); ventral surfaces uniformly grayish tan with very fine, dark, localized mottling on throat. In life ( Fig. 3 View FIGURE 3 ), dorsal surfaces of males tan, with or without dark symmetrical markings overall (uniformly blackish olive drab in females); dark transverse bars on the hind limbs poorly marked if present (absent in females); black postocular blotch present; in males, background color of throat, belly and ventrolateral surfaces khaki, with or without a yellowish tint on the throat that may shift to orange-red on the belly; rest of underparts, grayish brown to rosy brown; in females, all ventral surfaces uniform gray or deep purplish brown; a rusty tinge on the hidden surfaces of hind limbs is present in both males and females, almost always surrounding one or several amber to orange blotches in the axilla, groin and posterior surfaces of the thigh; these marks may be enclosed by black pigment; upper half of the iris pale goldenrod yellow; lower half, deep coppery brown; (14) SVL in females 24.6–26.4 (mean = 25.3 ± 0.6, n = 5), in males 17.4–20.1 (mean = 19.2 ± 0.7, n = 13); (15) body mass in living females 0.9–1.6 g, in males 0.5– 0.8 g.

Similar species. Pristimantis bambu differs from all other members of the P. o re s t e s group (i.e., P. a t r a b r a - chus, P. chimu , P. cordovae , P. corrugatus , P. melanogaster , P. orestes , P. pataikos , P. pinguis , P. seorsus , P. simonbolivari , P. simonsii , P. stictoboubonus , P. vetriguttatus , P. vidua ; sensu Hedges et al. 2008) by having slightly expanded, rounded to slightly truncate finger pads. Pristimantis corrugatus ( Duellman & Lehr 2009) may as well have expanded discs, but these are elliptical and wider than those of P. bambu . The new species may be further distinguished from all other species in the group ( Table 1 View TABLE 1 ), except from P. c h i m u, P. pinguis , P. seorsus and P. s i m o n s i i ( Duellman & Lehr 2009), by having ulnar tubercles coalesced into a low fold. Pristimantis chimu , P. seorsus and P. simonsii differ from P. b a m b u by lacking vocal slits; P. pinguis differs by having a differentiated tympanic membrane. From those species in the group bearing small eyelid tubercles (P. c h i m u, P. cordovae , P. o re s t e s, and P. v e n - triguttatus: Duellman & Lehr 2009; Lynch 1979), it differs by lacking a distinct discoidal fold. Finally, in life, P.

bambu is unique among the species assigned to the P. ore s te s group on the basis of the rusty pigment of the hidden surfaces of the hind limbs and the bold, black-bordered amber blotches on the groin and posterior surface of the thighs.

Description of the holotype. Adult male (QCAZ 46740; Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 ). Head slightly narrower than body, slightly longer than wide; upper eyelid bearing several, feebly visible tubercles; head width 35% of SVL; head length 36% of SVL; snout relatively short (snout to eye distance 17% of SVL), acuminate in dorsal view ( Fig. 1 View FIGURE 1 A) and rounded in profile; tongue longer than wide, posterior half notched and not adherent to floor of mouth; eye diameter slightly larger than eye–nostril distance; nostrils not protuberant, directed anterolaterally; canthus rostralis weakly concave in profile; loreal region slightly concave; upper eyelid width 58% of interorbital distance; cranial crests absent; tympanic annulus distinct, round; tympanic membrane absent; two enlarged postrictal tubercles, situated posteroventrally to tympanic annulus; choanae round, not concealed by palatal shelf of maxillary; vomerine odontophores posteromedial to choanae, oblique in outline, about the same size of choana, separated medially by distance less than width of odontophore, each bearing 5 teeth; vocal slits and median, subgular vocal sac present; skin on dorsum shagreen with widely interspersed low tubercles; dorsolateral fold visible on either side but only on anterior half of the body; middorsal fold fragmented, barely noticeable ( Fig. 1 View FIGURE 1 A); skin on venter areolate with no discoidal or thoracic folds ( Fig. 1 View FIGURE 1 B); cloacal sheath absent; cloacal region bordered ventrally by small, closely packed warts; ulnar tubercles coalesced into fold, continuous throughout forearm; outer palmar tubercle divided, inner portion larger and elliptical, outer portion smaller and round ( Fig. 2 View FIGURE 2 A); subarticular tubercles round in section; supernumerary palmar tubercles low and rounded, much lower than subarticular tubercles; fingers bearing narrow lateral fringes; Finger I shorter than Finger II; disc of Finger I barely expanded; all other discs expanded, rounded to slightly truncate ( Fig. 2 View FIGURE 2 A); ventral pads well defined by circumferential grooves; nuptial pads absent.

Tibia length 47% of SVL; foot length 45% of SVL; inner metatarsal tubercle present, about the same size of the outer, rounded and enlarged tubercle; subarticular tubercles round in section; plantar supernumerary tubercles indistinct; toes bearing narrow lateral fringes; webbing absent; discs of Toe I barely expanded; all other toe discs expanded, rounded to slightly truncated; toes with ventral pads well defined by circumferential grooves; relative length of toes: I <II <III <V <IV; Toe V slightly longer than Toe III ( Fig. 2 View FIGURE 2 B).

Measurements of holotype (in mm). SVL 20.04; tibia length 9.4; foot length 9.0; head length 4.5; head width 7.2; eye diameter 2.3; interorbital distance 2.6; upper eyelid width 1.5; internarial distance 2.0; eye-nostril distance 1.8.

Coloration of holotype in preservative. Dorsal surfaces pale brownish gray, with minute dark dots on the scapular and sacral region, distributed symmetrically on each half of the body, and with faint, dark transverse bars on the hind limbs ( Fig. 1 View FIGURE 1 A); upper lip with dark brown bars below eyes; dark brown supratympanic stripe present; background color of ventral surfaces khaki with a localized rusty tinge on the hidden surfaces of the hind limbs, which is also present but much fainter on the lower belly, palms and axillary region ( Fig. 1 View FIGURE 1 B).

Coloration of holotype in life (based on observations in the field and photographs; Figs. 3 View FIGURE 3 A, B). Dorsal surfaces light orangish brown, with faint, dark transverse bars on the hind limbs; flanks with same coloration as dorsum, with a dark brown postocular stripe accompanied by faint vertical supralabial stripes; background color of ventral surfaces khaki, finely mottled with dark pigment on the throat and strongly tinged with yellow on the throat and upper chest; palms, soles, ventral surfaces of hind limbs and groin intensely tinged with rusty to yellow, which becomes deep saffron on the belly as it fuses with the yellowish pigment of the throat; upper half of iris light goldenrod, lower half coppery brown.

Variation. Meristic variation is presented in Tables 2 and 3 View TABLE 3 . Some paratypes have two eyelid tubercles (QCAZ 46705, 46714, 46712, 46739, 46711, 26724), and others have only one (QCAZ 46725, 46704, 41444, 41606, 41616, 41620, 41672, 41694, 41738; Figs. 4 View FIGURE 4 , 5 View FIGURE 5 B); several paratypes have no visible dorsolateral fold (QCAZ 46706, 46714, 46725, 46711, 46742, 46724) nor middorsal fold (QCAZ 46725, 46711, 46742, 46724). In ethanol, the dorsum of one paratype is densely covered throughout with symmetrically distributed dark marks (QCAZ 46742; Fig. 6 View FIGURE 6 A), another one has a pale gray middorsal spot (QCAZ 46714), and yet another one (QCAZ 46710) has a light drab frontal patch. The dorsal background color of three paratypes is darker than the holotype (QCAZ 47555, 47556, 47557; Fig. 6 View FIGURE 6 D) or completely dark grayish brown altogether (QCAZ 46707); three male paratypes (QCAZ 46712,47555, 47557) have no localized rusty to light reddish brown pigment on the groin, axilla and hidden surfaces of the hind limbs. Most male paratypes (QCAZ 47555, 46726, 47556, 47558, 47557, 46711, 46712, 46714 46725, 46713, 46724, 46727, 46706, 46742) have pale cream spots on the groin and posterior surface of the thighs. Throat mottling is much more extensive in two male paratypes (QCAZ 46706, 46707). In preservative, the dorsal color becomes grayer and the rusty and yellowish tinge of the ventral surfaces is extensively lost. Specimens in life have well-defined tubercles and folds on the dorsum and legs, but those skin marks are much fainter in preservative.

Vocalization. The advertisement call of QCAZ 47558 (an adult male recorded on Reserva Mazar on 11 March 2010 at 22:08 h, temperature not recorded) can be characterized as a series of short, indistinctly pulsed, non-modulated notes in amplitud. The dominant frequency ranges between 2.50 and 2.56 kHz (maximum energy is 122.54 ± 1.74 dB; n = 20). The note repetition rate is 54.42 notes per minute, and the note length ranges between 0.005 and 0.006 s ( Fig. 5 View FIGURE 5 ). Internote intervals range between 0.816 and 1.782 s (mean = 1.195 ± 0.310 s; n= 20). Out of six recordings, call duration ranged between 12 and 103 s, with significant variation among note repetition rate. Vocalizing males decreased note intensity when approached by an observer. This is the first call described for a species in the P. o re s t e s group.

Etymology. This specific epithet bambu refers to the habitat preference of the new species, which is found in bamboo-dominated montane forests ( Chusquea sp). The epithet is a noun in apposition.

Distribution and natural history. Pristimantis bambu is known only from La Libertad, Reserva Mazar, (S2.54804, W78.69741), at elevations between 2876 and 2989 m.a.s.l ( Fig. 6 View FIGURE 6 ). This site, a family-owed alpaca ranch, is located in the eastern mountain range of Ecuador, on the southern edge of Sangay National Park, Cañar province. The area is a patchwork of native evergreen montane forest ( Valencia et al. 1999), shrub, secondary forest and pastures ( FCT 2008). Average temperatures at La Libertad are 18ºC and precipitation is 1200 mm per year. There are two distinct seasons: the dry season (Oct/Nov – Jan/Feb) and the wet season ( FCT 2008). Individuals of P. bambu were active during night on leaf litter and vegetation (20–155 cm above ground) within regrowth montane forest where bamboo ( Chusquea sp) is dominant. Individuals were seen active under overcast and cloudy nights, even under light drizzle, but not under heavy showers. During early morning, P. bambu was found active on the leaf litter, later during the day, individuals were found hidden in the leaf litter. Two individuals were hidden under piled up eucalyptus lumber and dead leaves far from the forest border, in pastures. Pristimantis bambu was found both near rivers and far from significant watercourses; but it was never found within primary forest. The species appears to be closely associated with secondary forests where the canopy cover is not complete, a habitat composed mainly of small trees, shrubs and bamboo. The species was also found on the forest border.

Females Males

(n = 5) (n = 13)

SVL 24.6–26.4 (25.3 ± 0.6) 17.4–20.1 (19.2 ± 0.7) Tibia length 11.9–12.4 (12.1 ± 0.2) 8.7–9.8 (9.3 ± 0.3) Foot length 11.3–11.7 (11.5 ± 0.2) 7.5–9.1 (8.4 ± 0.4) Head length 8.3–9.0 (8.6 ± 0.3) 6.1–7.2 (6.7 ± 0.3) Head width 8.4–9.3 (8.7 ± 0.3) 6.2–7.1 (6.6 ± 0.3) Interorbital distance 3.0–3.3 (3.1 ± 0.1) 2.2–2.6 (2.4 ± 0.1) Upper eyelid width 1.6–2.1 (1.9 ± 0.2) 1.5–2.0 (1.7 ± 0.1) Radioulna lenght 5.4–6.3 (5.8 ± 0.3) 4.2–4.7 (4.5 ± 0.1) Eye to nostril distance 2.2–2.4 (2.3 ± 0.1) 1.5–1.9 (1.7 ± 0.1) Snout to eye distance 4.0–4.3 (4.1 ± 0.1) 3.0–3.6 (3.3 ± 0.2) Eye diameter 2.5–2.7 (2.6 ± 0.1) 2.1–2.4 (2.2 ± 0.1) Tympanum diameter 1.0–1.5 (1.3 ± 0.2) 0.7–1.3 (1.1 ± 0.2) Hand lenght 6.1–6.4 (6.2 ± 0.1) 4.3–5.2 (4.9 ± 0.2) Finger I lenght 3.6–4.0 (3.7 ± 0.2) 2.6–3.1 (2.9 ± 0.2)

Females Males

During March 2010, a vocalizing male was heard. When searching it, a female Pristimantis bambu was found, presumably attracted by the male's vocalization. They were both bagged together and began amplexus 72 min afterwards. During the wet season, five males were heard vocalizing simultaneously along with another species ( Pristimantis pycnodermis ). A gravid female released 30 unfertilized eggs inside a plastic collecting bag. Sympatric species of P. b a m b u include, P. pycnodermis , P. gagliardoi , P. riveti , and two undescribed Pristimantis species.

During night, P. bambu remains still when approached by an observer; calling males may continue to vocalize even when approached, though some individuals may stop calling or foraging, even jumping away at times. At night, most individuals were found by standing 0.4–1.8 m from the vegetation and carefully scanning thin (2–10 mm in diameter) twigs, ferns, and leafs.

Discussion. The most recent comprehensive phylogeny of strabomantids includes four species assigned to the Pristimantis orestes group; two of them, P. o re s t e s and P. simonbolivari , cluster together, but the other species ( P. simonsii and P. melanogaster ) do not ( Hedges et al. 2008). Two scenarios explain the observed pattern: (i) the molecular phylogeny is accurate and the shared morphologies of the species included in the Pristimantis orestes group represent convergent evolution to cope with similar habitats ( Hedges et al. 2008), or (ii) the molecular phylogeny is not congruent with the evolutionary history of the these amphibians, and the Pristimantis orestes group is monophyletic. Since only a molecular phylogeny is at hand at the moment, we favor the first scenario. Both morphology and molecules support the lineage distinctiveness of P. b a m b u. Given our taxon sampling, P. bambu is most closely related to Pristimantis sp. ( Fig. 7 View FIGURE 7 ; corrected genetic distance = 5.9–6.8%), P. simonbolivari (corrected genetic distance = 7.7–7.8%), and P. o re s t e s (corrected genetic distance = 8.9%; Fig. 7 View FIGURE 7 ).

Species	Eyelid tubercles	Discs on outer fingers	Ulnar tubercles	Heel and tarsal tuber- cles	Vocal slits
P. atrabrachus	Absent	Barely wider than digit proximal to disc	Absent	Absent	Present
P. b a m b u	Several, barely visi- ble; or 1-2 small	Slightly expanded, rounded to slightly truncate	Coalesced into fold	Absent	Present
P. c h i m u	Several, small	Narrow, rounded	Coalesced into short fold	Absent	Absent
P. cordovae	Several, small	Barely expanded, emargin- ate	Present	Small tubercle on heel; absent on tarsus	Present
P. corrugatus	One prominent, conical tubercle	Expanded, elliptical, half the width of digit proximal to disc	Small, elongate	Conical tubercle on heel; one low, diffuse tubercle on tarsus	Present
P. melanogaster	Absent	Rounded, barely wider than digit proximal to disc	Absent	Absent	Absent
P. o re s t e s	Several, small, non- conical	Moderately dilated	Present, obscure	Small, non-conical	Present
P. pataikos	Absent	Rounded, barely wider than digit proximal to disc	Absent	Absent	Absent
P. pinguis	Absent	Rounded, barely wider than digit proximal to disc	Coalesced into short fold	Absent	Present
P. seorsus	Absent	Narrow, truncate	Present as tuber- cles or as a fold	Conical tubercle on the heel; those of tarsus forming ridges	Absent
P. simonbolivari	Absent	Barely expanded	Absent	Present only on heel	Present
P. s i m o n s i i	Absent	Rounded, barely wider than digit proximal to disc	Coalesced into low ridge	Absent	Absent
P. stictoboubonus	Absent	Narrow	Absent	Absent	Absent
P. ventriguttatus	Several, small	Broadly expanded, truncate	Present	Small, present on heel and tarsus	Present
P. v i d u a	Indistinct	Narrow	Absent	Present only on tarsus	Present

TABLE 3. Ranges of morphological proportions (in percentages) of adults of Pristimantis bambu. SVL = snout – vent – length.

	(n = 5)	(n = 13)
Tibia length/SVL	46.9–48.8	45.3–56.4
Foot length/SVL	43.7–46.7	40.9–45.9
Foot length/tibia length	93.2–95.8	77.0–96.1
Head width/SVL	32.9–37.0	23.8–36.2
Head length/SVL	33.0–35.9	32.1–37.4
Head length/head width	96.0–102.5	94.3–108.1
Eye-to-nostril distance/eye diameter	86.1–91.0	66.5–87.8
Upper eyelid width/IOD	49.3–69.8	59.2–82.8
Radioulna length/SVL	20.6–24.4	22.8–24.8
Hand length/radioulna length	98.9–118.4	101.5–115.0
Finger I length/hand length	55.2–66.0	52.9–65.7