Pristimantis minimus Terán-Valdez & Guayasamin, 2010

Terán-Valdez, Andrea & Guayasamin, Juan M., 2010, The smallest terrestrial vertebrate of Ecuador: A new frog of the genus Pristimantis (Amphibia: Strabomantidae) from the Cordillera del Cóndor, Zootaxa 2447, pp. 53-68 : 54-57

publication ID	https://doi.org/ 10.5281/zenodo.195104
DOI	https://doi.org/10.5281/zenodo.5671113
persistent identifier	https://treatment.plazi.org/id/4C7F8792-FFC0-FFA9-A08A-0873DCC6378A
treatment provided by	Plazi
scientific name	Pristimantis minimus Terán-Valdez & Guayasamin
status	sp. nov.

Treatment

Pristimantis minimus Terán-Valdez & Guayasamin , new species

Holotype. QCAZ 41612, an adult male ( Fig. 1 View FIGURE 1 , 2 View FIGURE 2 B) from the Cordillera del Cóndor, Miazi Alto (04.25656 S, 78.622456 W; 1300–1315 m.a.s.l.), Cantón El Pangui, Provincia Zamora Chinchipe, Ecuador ( Fig. 3 View FIGURE 3 ), collected by Juan M. Guayasamin, Elicio E. Tapia, and Holger Braun on 10 April 2009.

Paratypes. All paratypes (45 males, 25 females) were collected in two areas of the Cordillera del Cóndor, east and west of Río Nangaritza, within the Cantón Nangaritza, Provincia Zamora Chinchipe, Ecuador ( Fig. 3 View FIGURE 3 ); airline distance between the two localities is 6 km. Specimens collected east of Río Nangaritza are: 48 adult males ( QCAZ 40744–45, 41033, 41380, 41422, 41429, 41444, 41496, 41498, 41500, 41511, 41537, 41549, 41551, 41553, 41606, 41614, 41616–17, 41619–20, 41623, 41630–31, 41633, 41635, 41643, 41650, 41660–61, 41664–66, 41668, 41672, 41690–91, 41693–95, 41701, 41711, 41713, 41716, 41721–22, 41738), and 25 adult females ( QCAZ 41378, 41426, 41430–33, 41443, 41497, 41499, 41548, 41600, 41602, 41607, 41613, 41621, 41634, 41651, 41667, 41670–71, 41673, 41689, 41714, 41718, 41723) from the type locality, Miazi Alto (04.25656 S, 78.622456 W; 1300–1315 m.a.s.l.), collected by Juan M. Guayasamin, Holger Braun, Elicio E. Tapia on 06–12 April 2009; QCAZ 41495, cleared-and-stained (04.24584° S, 78.61497° W; 1415 m.a.s.l.); QCAZ 41537, 41548–49, 41551, 41553 (04.24663° S, 78.62119° W; 1432 m.a.s.l.); QCAZ 41643, 41650–51 (04.25026° S, 78.61746° W; 1256 m.a.s.l.); QCAZ 41511, 41600, 41602, 41606–07, 41660–61, 41664–68, 41670–73 (04.25628° S, 78.62225° W; 1260–1300 m.a.s.l.); QCAZ 41613, 41614, 41616–21, 41623, 41630–31, 41633–35 (04.25656° S, 78.62246° W; 1314 m.a.s.l.). The following specimens were collected on mountains west of Río Nangaritza by Elicio E. Tapia, Jessica L. Deichmann, Sylvia Aldás on 17– 18 April 2009: QCAZ 41378, 41380, 41426, 41430–31, 41443 (04.25523º S, 78.67314º W; 1300 m.a.s.l.); QCAZ 40744–45, 41433, 41689–91, 41693–95, 41721–23, 41738 (04.25789º S, 78.68166º W; 1554 m.a.s.l.); QCAZ 41701 (04.25669º S, 78.67798º W; 1418 m.a.s.l.); QCAZ 41711, 41713–14, 41716, 41718 (04.25971º S, 78.68630º W; 1685 m.a.s.l.).

Generic placement. Some of the main traits shared by all Pristimantis include: (1) head as wide as body; (2) cranial crests absent; (3) dentigerous process of vomers present; (4) terminal discs on digits expanded, with circumferential grooves and terminal phalanges T-shaped; (5) Toe V larger than Toe III ( Hedges et al. 2008). All traits observed in the new species agree with the diagnosis of Pristimantis . However, no synapomorphy has been yet identified for the genus Pristimantis and, indeed, three other genera ( Eleutherodactylus , Ischnocnema , Craugastor ) share the same diagnostic characters. In the genus Craugastor (family Craugastoridae ), species have a sexually dimorphic tympanum (larger in males), although sexual dimorphism for the tympanum has not been determined in the subgenus Hylactophryne ( Hedges et al. 2008) ; most species in Pristimantis do not present a sexually dimorphic tympanum ( Hedges et al. 2008). Given that many clades have restricted geographic ranges, distribution provides an indirect clue to determine the generic placement of newly discovered taxa (see Guayasamin et al. 2009). For example, Craugastor is distributed mostly in Central America, marginally reaching northwestern South America (northeastern Honduras southeastward through Nicaragua, Costa Rica, and Panama to northwestern Ecuador; modified from Hedges et al. 2008); Eleutherodactylus (family Eleutherodactylidae ) is distributed throughout the West Indies, peninsular Florida, southern Texas, northern Central America ( Frost 2009); Ischnocnema (family Brachycephalidae ) is restricted to the Atlantic Coastal Forest in eastern Brazil and in extreme southeastern Brazil and northern Argentina ( Hedges et al. 2008); whereas, Pristimantis is found in southern Central America, most of South America, and on islands in the Lesser Antilles closest to the mainland of South America ( Trinidad and Tobago, Grenada, St. Vincent; Hedges et al. 2008). Therefore, the newly discovered Pristimantis , based on geography, is likely to be part of Pristimantis , an hypothesis that should be tested with molecular data.

Diagnosis. A species of Pristimantis having the following characters: (1) skin on dorsum smooth to slightly shagreen, lacking tubercles or folds; venter shagreen, lacking discoidal or thoracic folds ( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 ); (2) tympanic membrane absent, tympanic annulus present but not visible externally; (3) snout short, rounded in dorsal and lateral views; (4) upper eyelid lacking enlarged tubercles, when present tubercles are low and almost undistinguishable from surrounding skin texture; upper eyelid slightly smaller or as wide as interorbital distance; cranial crests absent; (5) dentigerous process of vomers well developed, the number of teeth in each process varies from 1 to 4; (6) males with a small subgular vocal sac, vocal slits present, nuptial pads absent; (7) Finger I shorter than Finger II; discs on fingers expanded and rounded, except for Finger I that is only slightly expanded, disc on Finger III acute ( Fig. 4 View FIGURE 4 A, C, Fig 5 View FIGURE 5 A, B); (8) fingers lacking lateral fringes; outer palmar tubercle bifid; distinct supernumerary tubercles ( Fig. 4 View FIGURE 4 C), (9) ulnar and tarsal tubercles absent; (10) heel lacking tubercles; (11) toes lacking lateral fringes; webbing absent; Toe V slightly longer than Toe III; toe discs expanded, rounded ( Figs. 4 View FIGURE 4 B, D); (12) inner metatarsal tubercle oval, about twice the size of outer metatarsal tubercle; supernumerary plantar tubercles present ( Fig. 4 View FIGURE 4 D); (13) in ethanol, dorsal coloration variable ( Figs. 1 View FIGURE 1 , 6 View FIGURE 6 ): brown, pale brown-cream, brown-reddish, brown-grayish or gray, with dark brown scapular and sacral marks; white mid-stripe can be present or absent; brilliant silver and/or bronze chromatophores distributed on dorsum; venter cream to brown; throat pale brown to brown; minute white and brown dots on venter and throat seen under magnification. In life ( Fig. 2 View FIGURE 2 ), dorsum brown-orange to yellowish brown with darker marks, flanks as dorsum but with small white dots; venter grayish brown with minute white dots; belly partially translucent; red iris with thin black reticulation; (14) SVL in females 15.3–18.9 mm (mean = 16.9 ± 1.0, n = 25), in males 9.5–13.7 mm (mean = 12.2 ± 0.8, n = 46).

Similar species. Pristimantis minimus is easily distinguished from most species in Pristimantis by its minute body size. Other small South American Pristimantis , although larger than P. minimus , include P. coronatus (SVL = 15.3 mm in the only known specimen, a female; Lehr & Duellman 2007), P. andinognomus (SVL = 10.0–14.5 mm in adult males; 12.6–17.9 mm in adult females; Lehr & Coloma 2008), and P. trachyblepharis (SVL = 12.1–15.8 mm in adult males; 15.8–19.2 mm in adult females; Lynch & Duellman 1980). Pristimantis coronatus has an occipital fold, ulnar tubercles, conical tubercles on the upper eyelid, and a red-orange coloration on flanks and groin (absent in P. minimus ). Pristimantis andinognomus presents dorsolateral and postocular folds, conical tubercles on the upper eyelid and heel, tarsal tubercles, and a distinctive tympanic membrane (absent in P. minimus ). Finally, P. trachyblepharis is distinguished by lacking vocal slits (present in P. m i n i m u s) and having an externally evident tympanum (concealed in P. m i n i m u s). Other small species of Pristimantis from Ecuador are notably different from P. m i n i m u s. Males of P. caeruleonotus are slightly larger (11.6–14.6 mm in males; 20.5–22.6 mm in females; Lehr et al. 2007) than P. minimus . Additionally, P. caeruleonotus presents a visible tympanum and lateral fringes in fingers, characteristics that are absent in P. minimus . From other relatively small species, P. minimus is differentiated mainly by the smaller size, but also the absence of conical upper eyelid tubercles, which are present in P. colodactylus ( Lynch, 1979) , P. hectus ( Lynch & Burrowes, 1990) , P. leoni ( Lynch, 1976) and P. pyrrhomerus ( Lynch, 1976) . Additionally, P. l e o n i and P. pyrrhomerus bear ridges on the dorsum and inner and outer tarsal tubercles (absent in P. minimus ). Pristimantis species that were found in sympatry with P. minimus include P. diadematus , P. trachyblepharis , and P. katoptroides ; at Cordillera del Cóndor, these three species have a larger body size that does not overlap with P. minimus [in P. trachyblepharis , SVL (males) = 13.7–16.2 mm, n = 15, SVL (females) = 18.9–22.2 mm, n = 6; in P. diadematus , SVL (males) = 17.9–26.9 mm, n = 8, SVL (females) = 26.7–32.2 mm, n = 6; P. katoptroides , SVL in one adult female = 32.3 mm]. Moreover, P. katoptroides is easily distinguished from all other Pristimantis by having a green venter with white reticulation and a blue groin.

Description of the holotype. Adult male (QCAZ 41612; Figs. 1 View FIGURE 1 , 2 View FIGURE 2 B). Head as wide as body, slightly longer than wide, lacking tubercles; head width 35% of SVL; head length 38% of SVL; snout short, rounded in dorsal and lateral views ( Fig. 2 View FIGURE 2 ); tongue oval, with a small notch on its posterior border; eye diameter slightly larger than eye-nostril distance; nostrils slightly protuberant, directed anterolaterally; canthus rostralis straight in dorsal view and in profile; loreal region weakly concave; upper eyelid width 74% of interorbital distance, lacking tubercles; tympanic membrane absent; tympanic annulus present, but not visible externally. Vocal slits straight, located at the level of the junction of the upper and lower lips, between tongue and margin of jaw; vocal sac small, restricted to throat. Skin on dorsum shagreen without tubercles or folds ( Fig. 1 View FIGURE 1 ); skin on venter shagreen, discoidal or thoracic folds absent ( Fig. 2 View FIGURE 2 B); cloacal sheath absent; cloacal region without tubercles. Ulnar tubercles absent; outer palmar tubercle bifid, about the same length as oval inner palmar tubercle; subarticular tubercles rounded; distinct, non-conical supernumerary palmar tubercles, lower than subarticular tubercles; fingers lacking lateral fringes; Finger I shorter than Finger II; disc of Finger I slightly expanded, all other discs expanded ( Fig. 4 View FIGURE 4 A); ventral pads well defined by circumferential grooves; nuptial pads absent.

Tibia length 54% of SVL; foot length 46% of SVL; surfaces of legs smooth, lacking tubercles; inner metatarsal tubercle ovoid, about twice the size of outer metatarsal tubercle; subarticular tubercles rounded, well defined; plantar supernumerary tubercles present, smaller than subarticular tubercles; toes lacking lateral fringes; webbing absent; discs expanded, round to acute, similar to those on fingers; toes with ventral pads well defined by circumferencial grooves; relative length of toes: I <II <III <V <IV; Toe V slightly longer than Toe III ( Fig. 3 View FIGURE 3 B).

Measurements of holotype (in mm). SVL 11.9; tibia length 5.6; foot length 5.5; head length 4.5; head width 4.2; eye diameter 1.8; interorbital distance 1.4; upper eyelid width 1.0; internarial distance 1.5; eyenostril distance 1.2.

Coloration of holotype in preservative. Background color of dorsum light brown-cream with a continuous large dark brown mark from snout to sacral region, only divided by a white, thin middorsal stripe and a white interorbital band ( Fig. 1 View FIGURE 1 ); upper lip with dark brown bars below eyes; dark brown supratympanic fold; silver and bronze brilliant sparkling distributed on dorsum; dark brown mark surrounding the cloaca; minute white dots on the flanks; dorsally, arms and legs with pink hue, barred thighs, forearm with one brown stripe; ventral coloration (including arms and legs) cream with numerous minute brown dots and scarce white dots seen under magnification ( Fig. 1 View FIGURE 1 ).

Coloration of holotype in life (based on observations in the field and on photographs; Fig. 2 View FIGURE 2 B). Brownorange dorsum, with a thin middorsal line and a large brown mark; flanks with same coloration as dorsum, but with small white dots; venter grayish brown with minute white dots; belly translucent, therefore the heart, liver, and viscera are partially visible through the skin; red iris with thin black reticulation.

Variation. Meristic variation is presented in Table 1 View TABLE 1 . Some paratypes have the discs of the fingers more expanded than the holotype (QCAZ 41422, 41432, 41511, 41691, 41711, 41716; Fig. 5 View FIGURE 5 A), and others have the tip of the discs slightly acuminate (QCAZ 40744, 40745, 41444, 41606, 41616, 41620, 41672, 41694, 41738; Fig. 5 View FIGURE 5 B). In ethanol, two paratypes have two white dorsolateral stripes starting at the nostrils and ending just anterior to the cloaca (QCAZ 41430, 41537; Fig. 6 View FIGURE 6 A). Most paratypes do not have the white, thin middorsal stripe (QCAZ 40744, 40745, 41378, 41380, 41422, 41426, 41429, 41431, 41432, 41433, 41443, 41444, 41497, 41511, 41548, 41551, 41553, 41602, 41620, 41631, 41635, 41650, 41660, 41661, 41666, 41689, 41690, 41691, 41693, 41694, 41695, 41701, 41711, 41713, 41714, 41716, 41718, 41721, 41722, 41723, 41738; Fig. 6 View FIGURE 6 D). The background coloration of the dorsum varies from gray (QCAZ 41422, 41429, 41433, 41444, 41498, 41499, 41500, 41548, 41613, 41650, 41661, 41664, 41667, 41671, 41672, 41673, 41691; Fig. 6 View FIGURE 6 B) to brown-grayish (QCAZ 40744, 41380, 41443, 41549, 41600, 41602, 41607, 41631, 41643, 41665, 41666, 41668, 41670, 41690, 41695, 41713, 41714; Fig. 6 View FIGURE 6 C), brown (QCAZ 40745, 41378, 41431, 41432, 41511, 41614, 41616, 41617, 41620, 41621, 41623, 41426, 41630, 41633, 41634, 41651, 41660, 41689, 41693, 41694, 41701, 41711, 41716, 41718, 41721, 41722, 41723; Fig. 6 View FIGURE 6 D) and brown-reddish (QCAZ 41619, 41496, Fig. 6 View FIGURE 6 E). Some paratypes have a scapular mark W-shaped and a sacral V-shaped mark (QCAZ 41378, 41422, 41429, 41433, 41444, 41497, 41548, 41551, 41553, 41602, 41660, 41661, 41667, 41671, 41672, 41691, 41738; Fig. 6 View FIGURE 6 B). The venter of most paratypes (specially those with brown, brown-grayish or brown-reddish dorsum) is cream brown, being the throat darker than the belly ( Figs. 6 View FIGURE 6 F, 6G); in preservative, the belly is not as translucent as in life. Specimens in life show low and scarce tubercles on the upper eyelid, dorsum and legs, but those tubercles are not visible in preservative.