Pseudoeurycea ruficauda, Parra-Olea & García-París & Hanken & Wake, 2004

Parra-Olea, G., García-París, M., Hanken, J. & Wake, D. B., 2004, A new species of arboreal salamander (Caudata: Plethodontidae: Pseudoeurycea) from the mountains of Oaxaca, Mexico, Journal of Natural History 38 (16), pp. 2119-2131 : 2122-2126

Pseudoeurycea ruficauda sp. nov.

(Orange-tailed agile salamander; Salamandra colirroja) ( figures 1 , 2 )

HOLOTYPE: IBH 13806, a subadult male from ca 1 km NW of Puerto Soledad, Sierra Mazateca , Oaxaca, Mexico, elevation 2290 m, 18‡10.450’N, 97‡00.197’W, collected 14 January 2002 by M. García-París, J. Hanken, G. Parra-Olea and D. Wake.

PARATYPES: IBH 13802–13805 (four specimens) , MVZ 236762 , MCZ A-135811 and MNCN 41042 , same data as the holotype ; IBH 13801, 7 km (rd) W of Plan de Guadalupe, Sierra Mazateca, Oaxaca, Mexico, elevation 2235–2240 m, 18‡09.164’N, 96‡58.509’W .

Referred specimens. MZFC 13316–17 (two specimens), vicinity of the type locality .

Diagnosis. This is a medium-sized arboreal species of Pseudoeurycea ( SL to about 45 mm) with long legs and broadly spread hands and feet having long, separated digits. It is distinguished from other members of the genus by its long legs, broad hands and vivid coloration, which includes a red-orange tail and mottled black and orange head and body. In addition to coloration, it differs from other long-legged, arboreal Pseudoeurycea , including its closest relative P. unguidentis (Taylor, 1941) , and the other arboreal member of the P. juarezi Regal, 1966 group, P. saltator Lynch and Wake, 1989 , in having a less robust appearance, with slender legs and tail, and a prominent head that is well differentiated from the trunk. Live specimens are readily characterized by their alert attitude and rapid movements, including jumps, in which they resemble P. saltator . The other members of the P. juarezi species group, P. juarezi and P. aurantia Canseco-Márquez and Parra-Olea, 2003 , two species with terrestrial habits that inhabit the Sierra de Juárez, differ from P. ruficauda in having stouter bodies, shorter legs, broader heads, shorter tails and smaller digits. The coloration of P. aurantia resembles that of P. ruficauda except that P. aurantia possesses a dull orange coloration, uniformly extended, without defined limits over the dorsal areas, less bright and sharp than the yellow-orange dorsal stripe of P. ruficauda . The species also is distinct in biochemical characters.

Description. Subadult specimens in the type series range from 23.7 to 30.2 mm SL, mean 25.6 mm, but adults reach at least 45 mm. The head is relatively large and prominent with large, frontally directed eyes that protrude on each side: head width 4.2–5.0, mean 4.6 mm; head depth 2.3–2.8, mean 2.5 mm; head length 6.2–7.4, mean 6.8 mm. SL is from 5.4 to 6 times head width. Nostrils are small (mean diameter 0.3 mm) and widely separated (1.2–1.6, mean 1.4 mm). Parotoid glands are not evident. The body is slender; shoulder width across the anterior limb insertions is from 3 to 3.6, mean 3.2 mm. Costal grooves are 13, counting one each in axilla and groin. Tails are slender and taper to a narrow tip. They are slightly shorter than SL (mean tail length 22.9 mm), except in the largest paratype, a 30.2 mm SL female. Legs are long (6.2–8.6, mean 7.5 mm) and usually touch or overlap by 1.0–1.5 costal folds when appressed to the side of the body; the legs fail to overlap by about one costal fold in the largest paratype. Hands and feet are broadly spread (foot width 2.4–3.4, mean 2.9 mm) and the digits are long and slender with distinct subterminal pads. The fifth digit is well developed but noticeably shorter than the fourth. Teeth are relatively numerous: premaxillary 5–8, mean 7; maxillary 27–49, mean 41.1; and vomerine 11–16, mean 14.3. Mental gland is not evident.

This is a colourful species with a generally two-tone pattern. Dorsal coloration is orange-tan with coppery-gold highlights that are mixed with black. An irregular and sometimes discontinuous dorsal stripe that varies from tan-yellow, to orange, to reddish brown extends from the nape to the tip of the tail. The stripe is often interrupted by small black spots; these are denser laterally, where they form a more or less continuous black stripe. Flanking black bands run from the scapular region to the base of the tail, where they often are broken into isolated spots dispersed over the tail. The tail is basically orange with black spots and has a vivid, redorange to yellow-orange tip. The head is generally dark brown with dense black mottling, yet is overlain by bright iridophores. In several specimens, a black V-shaped mark begins on the upper eyelids and extends posteriorly. Flanks are black but also heavily spotted with gold, yellow, copper, cream and white, giving them a marbled appearance. A distinctive thin black stripe runs from the nostril through the eye, then curves to reach the anterior limb insertion. Upper forelimbs are rusty orange; hind limbs are somewhat duller. Digit tips are reddish. The iris is coppery or rusty gold reticulated with black. The belly is greyish and largely unmarked, but it is darker in some specimens and there are occasional light spots. The throat and lower jaw are heavily pigmented and the colour is a complex mixture of dark brown, yellow and rusty orange, all overlain by scattered small white spots.

Measurements of the holotype (in millimetres). Head width 4.6; snout to gular fold (head length) 6.7; head depth at posterior angle of jaw 2.5; eyelid width 1.4; eyelid length 2.1; anterior rim of orbit to snout 1.7; horizontal orbital diameter 1.5; interorbital distance 3.0; eye to nostril distance 1.1; distance separating external nares 1.6; nostril diameter 0.3; snout projection beyond mandible 0.6; snout to posterior angle of vent (standard length) 25.3; snout to anterior angle of vent 24.0; snout to forelimb 8.8; axilla to groin 13.3; limb interval 21; shoulder width 3.6; tail length 22.5; tail width at base 1.8; tail depth at base 2.0; forelimb length (to tip of longest toe) 7.3; hind limb length 7.9; hand width 2.0; foot width 3.0; length of longest toe (3) 1.2; length of shortest toe (5) 0.6; numbers of teeth: premaxillary 7, maxillary 45, vomerine 14.

Coloration of the holotype (in life). This is a brightly coloured animal with a complex mosaic of orange-tan and black. A dorsal orange stripe is mottled with black spots, bordered with black stripes, and overlain with metallictan iridophores. A distinctive, thin black stripe runs from the nostril through the eye, then curves to reach the anterior limb insertion. The tail is orange with black spots. Flanks are black. The belly is dark and largely unmarked, but there is metallic-orange and copper speckling in the throat region and near the jaw.

Coloration of the holotype (in preservative). Lively coloration. There are tan-orange markings on the head, limbs and body. The tail is bright red to redorange (some black spots) with a bright orange tip. The head is strongly mottled with black and yellow to tan-orange. A highlighted metallic stripe extends from the eye to the forelimb insertion, immediately above a prominent black stripe. A black V-shaped mark is evident on the back of the head. A broad dorsal stripe starts in the nuchal region and becomes progressively brighter posteriorly. It is irregularly bordered. Lateral surfaces are black with bright cream-yellow patches. Sides of the tail are black with orange spots. Limbs are mainly mottled orange and dull rusty black. Hands and feet are irregularly mottled. The venter is grey (punctate melanophores) with some light yellow speckles anteriorly. The gular area is strongly mottled with black and orange. The face region is orange with black infusions. Eyelids are black. The iris is dark metallic brown-gold.

Variation. The single specimen from west of Plan de Guadalupe ( IBH 13801) ( figure 2 ) differs somewhat from the rest of the type series in being generally rusty to bright red-orange over the entire dorsum, becoming progressively brighter posteriorly. The belly is blackish with scattered rusty spots along the ventral midline; the same rusty spots densely cover the throat region. This is the smallest specimen (23.7 mm SL), and it has the largest nostrils (0.4 mm) and the fewest teeth .

Habitat and range. The species is known from two general localities in the western portion of the Sierra Mazateca, Oaxaca. This mountain range lies within the Sierra Madre Oriental, north of the Río Grande. Both localities, which are only a few kilometres apart, lie within high elevation, moist, pine–oak forest, with oaks dominating at present. Arbutus is also common, as is Baccharis . There is abundant surface litter and many downed, rotting logs and tree branches. Epiphytes, including bromeliads and ferns, are relatively common. One small log with somewhat loose bark yielded six specimens; most were found under the bark but two specimens were exposed deep inside the log. Two specimens were taken from bromeliads of intermediate to small size located about 2 m above ground. One specimen was taken from a road bank, about 15 cm deep in a tight stone crevice in loose, reddish rock.

Three species of salamanders have been found in sympatry with Pseudoeurycea ruficauda : Cryptotriton adelos (Papenfuss and Wake, 1987) (Luis Canseco-Márquez, personal communication), Thorius schmidti Gehlbach, 1959 ( García-París and Parra-Olea, 1999) and a second, undescribed species of Thorius , which appears to be endemic to the Sierra Mazateca. One more undescribed species of Pseudoeurycea related to P. mystax Bogert, 1967 and another undescribed species of Thorius occur in the Sierra Mazateca (Parra-Olea et al., in preparation), but neither has been found in strict sympatry with P. ruficauda .

Etymology. The epithet ruficauda is derived from the Latin words rufous (reddish) and cauda (tail). It refers to the brightly coloured, reddish orange tail of this species.

Remarks. Two specimens deposited in MZFC ( UNAM, Mexico) are referred to the above species. Both were collected under logs near the type locality (Luis Canseco-Márquez, personal communication), but each has been dissected and the coloration has already faded. The larger of the two specimens is about 45 mm SL (the other one is about 36 mm SL), indicating that Pseudoeurycea ruficauda attains a much larger adult size than would be suggested by the type series alone. The larger specimen is uniformly dark, but it has a mottled throat and the extreme tip of the tail is light, suggesting a bright colour in life. The second specimen has a bright dorsal stripe bordered by dark coloration; the tail is mottled with light and dark pigment and is light at the tip. Limbs of both specimens are long and touch or overlap when appressed to the body. Digits are long and slender.

Molecular characters. We sequenced a total of 1833 base pairs of the mitochondrial genome of three specimens of P. ruficauda , two from west of Puerto Soledad, the third from 7 km west of Plan de Guadalupe. These sequences were compared to previously published sequences of all species groups of Pseudoeurycea (Parra-Olea, 2002) . Sequences are identical (0% divergence) in the two specimens from Puerto Soledad. Divergence (uncorrected p) between these specimens and the one from 7 km west of Plan de Guadalupe is relatively high (1.1% 16S, 2.8% Cyt b, 4.0% ND 4) despite their geographic proximity. However, these sequences are more similar to each other than to any other known mtDNA sequence of Pseudoeurycea .

The smallest sequence divergence from P. ruficauda to any other species is to populations from the Sierra de Juárez that are tentatively assigned to P. unguidentis (2.8% 16S, 6.1–6.7% Cyt b, 9.5–9.7% ND4; Parra-Olea, 2002; see below). The level of divergence between P. ruficauda and each previously defined species group is large, including the P. juarezi group (3.8–4.0% 16S, 7.6–7.9% Cyt b, 11.0–12.0% ND 4); the P. leprosa (Cope, 1869) group (4.6–6.7% 16S, 8.2–11.0% Cyt b, 11.4–16.5% ND 4); the P. gadovii (Dunn, 1926) group (4.6–7.4% 16S, 8.5–9.8% Cyt b, 12.7–15.1% ND 4); and the P. bellii (Gray, 1850) group (7.9–8.5% 16S, 11.1–12.5% Cyt b, 17.3–19.4% ND 4).

Phylogenetic relationships

The topology obtained in the ML (2ln L ~15369.15) and Bayesian analyses ( figure 3) is very similar to that obtained in the MP analysis (a single most parsimonious tree, L~2647 steps, consistency index ( CI)~0.408, retention index ( RI)~0.563, 587 characters were parsimony informative; figure 4). The only difference involves the position of P. galeanae (Taylor, 1941) and P. bellii with respect to P. cephalica (Cope, 1869) . In the ML and Bayesian topologies P. galeanae is sister to the P. cephalica clade, with P. bellii basal to both of them ( figure 3). The single MP tree instead shows P. bellii as sister to the P. cephalica clade, with P. galeanae basal (d2; figure 4).

The ML topology resembles the one published earlier for the genus Pseudoeurycea (Parra-Olea, 2002) , except that P. unguidentis now forms a monophyletic group with P. ruficauda . This sister taxon relationship is also present in Bayesian (pp 100) and MP analyses (bs 98). The clade formed by P. unguidentis and P. ruficauda is included in the P. juarezi species group, although MP support values and decay for the group are low (bs 41, d3). Analyses of phylogenetic relationships within this clade are further complicated by uncertainty regarding the specific identity of the population assigned to P. unguidentis ( Parra-Olea, 1999, 2002). These specimens, from the Sierra de Juárez, Oaxaca, appear to be smaller and longer-legged than those from the type locality, on Cerro San Felipe in the Sierra Aloapaneca, Oaxaca; they may represent a distinct, undescribed taxon. Topotypic samples of P. unguidentis for genetic analysis are unavailable. All analyses provide support for previously defined species groups: P. gadovii (pp 99, bs 99, d15), P. leprosa (pp 100, bs 75, d8), P. juarezi (pp 100, bs 41, d3) and P. bellii (pp 100, bs 96, d10).

Relationships among main clades are fully resolved by MP analysis, although support for these relationships is weak. The P. leprosa group, which includes Lineatriton , forms a clade with the P. juarezi group (pp support 100, bs 30, d3). This clade, in turn, is sister to the P. gadovii group (pp 93, bs 44, d3). The P. bellii clade is basal to all other Pseudoeurycea .

Figures

FIG. 1. Pseudoeurycea ruficauda. Subadult from the type locality (IBH 13806), with typical coloration.

FIG. 2. Pseudoeurycea ruficauda. Subadult from 7 km (rd) W of Plan de Guadalupe, Sierra Mazateca, Oaxaca (IBH 13801). Colour variant.