Craugastor saltator ( Taylor 1941 )

Jameson, Tom J. M., Streicher, Jeffrey W., Manuelli, Luigi, Head, Jason J. & Smith, Eric N., 2022, Miniaturization in Direct-Developing Frogs from Mexico with the Description of Six New Species, Herpetological Monographs 36 (1), pp. 1-48 : 37-38

Craugastor saltator ( Taylor 1941)

Eleutherodactylus saltator Taylor 1941:89 . Holotype female ( FMNH 100116 ) from ‘‘Omilteme, Guerrero, Mexico.’’ [Examined] .

Eleutherodactylus mexicanus: Lynch 2000:134 . [Misidentification].

Craugastor saltator (Taylor) : Crawford and Smith 2005:536.

Diagnosis. —Based on holotype and three additional specimens. Aspecies of Craugastor distinguished by the following combination of characters: (1) large adult size (maximum SVL ¼ 44 mm); (2) full ossification of skeleton in adults but under a different ontogenetic sequence than other members of the series ( Table 3 ), where the sphenethmoid, humeral interior epiphyses, and tibiofibular epiphyses do not ossify during stage 3, the fontopareital-prootic suture does not offset posteriorly during stage 4, and the epicorocoids do not ossify during stage 6; (3) presence of posterolateral projection of the frontoparietal; (4) presence of vomerine odontophores; (5) presence or absence of raised tubercles on eyelids; (6) supratympanic fold developed; (7) face flank, labium barred or dark with a cream stripe above; canthal stripe complete or broken; (8) one or two postrictal tubercles; (9) gular region with trace of mid-pale stripe; (10) dorsal surface unicolored, blotched, or with wide middorsal stripe bordered by cream-colored stripes, dark interorbital bar, sometimes with small suprascapular and/or rump spots; (11) middorsal ridge present; (12) dorsum smooth or slightly tuberculate; (13) body flank unicolored, rarely supratympanic stripe extending to area behind insertion of arm, making anterior area darker; finely shagreened; (14) inguinal gland present and axillary gland present in adults; (15) when leg adpressed to body, heel reaches beyond snout; (16) outer tarsal ridge with 0–5 extremely small, flat, and round tubercles, no raised fringe or ridge; (17) finger and toe pads round and expanded; (18) inner metatarsal tubercle larger than outer metatarsal tubercle.

Comparisons. — Craugastor saltator can be differentiated from C. bitonium , C. cueyatl , C. hobartsmithi , C. pygmaeus , and C. rubinus by the absence of vomerine odontophores (present in C. saltator ). It can be differentiated from C. candelariensis and C. portilloensis by equal sizes of the inner and outer metatarsal tubercles (unequal sizes in C. saltator ). It can be differentiated from C. omiltemanus by ventral skin texture in life; smooth to granular in C. saltator versus areolate in C. omiltemanus . It can be differentiated from C. montanus and C. polaclavus by shorter relative leg sizes with a crus ratio of 50–58% SVL (long relative leg sizes of 62–73% SVL in C. saltator ). Craugastor saltator is most similar to C. mexicanus ; however, they do not overlap in geographic range (see C. mexicanus account for additional information).

Description. —Detailed description in Taylor (1942). Described as large-bodied, long-legged, with pigmented testes, unequal inner and outer metatarsal tubercle sizes, large vomerine odontophores, and generally smooth dorsal skin ( Taylor 1941); with less population-level chromatic variation than its relative C. mexicanus ( Lynch 2000) .

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Holotype ( FMNH 100166) large female ( SVL ¼ 44 mm; Fig. 36 ) with relative finger lengths III> IV> II> Iand relative toe lengths IV> III> V > II> I. Asubadult individual used in the molecular analysis, UTA A- 66120 ( Fig. 36 ) had the following characteristics: SVL ¼ 14.5 mm; tympanum width ¼ 1.2 mm; naris–snout length ¼ 0.7 mm (4.7% SVL); eye–nostril distance ¼ 1.5 mm (10.3% SVL); relative finger lengths III> IV> II> I; relative toe lengths IV> III> V > II> I; unlike adult specimens, inner metatarsal tubercle and outer metatarsal tubercle near equal in length.

Distribution. —Known only from the high-elevation pine–oak forests of Guerrero in the Sierra Madre del Sur ( Fig. 6 ).

Phylogenetics. —We were only able to sequence mtDNA data for C. saltator , so only it was included in the concatenated and mtDNA analyses. In the concatenated analysis, it was recovered as the sister taxon of C. omiltemanus with limited support (ML ¼ 44; BAYES ¼ 0.74; Fig. 3 ). In the mtDNA-only analysis, support for this relationship was lower in the ML analysis but higher in the BAYES analysis (ML ¼ 33, BAYES ¼ 0.82; Fig. 4 ). In terms of genetic distances ( Table 4 ), C. saltator was most similar to C. mexicanus (5.1%), followed by similarity to C. omiltemanus (5.6%).

Remarks. —The skull of C. saltator is similar to that of C. mexicanus and C. omiltemanus , with more anteriorly placed anterior suture of the frontoparietal and prootic than in other species. Taylor (1941:91) makes multiple references to C. saltator and C. omiltemanus (as Eleutherodactylus calcitrans ) being similar and states that these two species can be differentiated by the ‘‘very long limb, and the reduced inner metatarsaltubercle [of C. saltator ].’’ Lynch (2000) noted that C. saltator is actually far more similar to C. mexicanus from adjacent Oaxaca and subsequently synonymized C. saltator with C. mexicanus (see Methods, Taxonomic History). Despite the finding of Crawford and Smith (2005), which were used to revalidate C. saltator , at one point in our study one of us (JWS) was convinced by Lynch’s (2000) argument that C. saltator should be a junior synonym of C. mexicanus . The basis for this suspicion was (1) a specimen collected by J.D. Godman from Omilteme, Guerrero (the type locality) identified by J.D. Lynch as C. saltator on 13 January 1972 (BMNH 1901.12.19.24) is similar in morphology to C. mexicanus ; (2) the nDNA analysis of Crawford and Smith (2005) found C. mexicanus þ C. saltator to be monophyletic; and, (3) we did not observe range overlap between C. mexicanus and C. saltator ( Fig. 6 ), which may be consistent with a single large-bodied, long-legged species inhabiting the Sierra Madre del Sur. However, as in Crawford and Smith (2005), our mtDNA phylogenetic results did not recover C. mexicanus þ C. saltator as monophyletic ( Fig. 3 ) and the specimens of C. saltator we examined had on average larger body sizes and differing toe length formulae than did C. mexicanus ( Figs. 10 and 11 ; Table 6 ). As such, we continue to recognize C. saltator as a distinct species pending further taxonomic investigation. Craugastor saltator likely co-occurs with C. bitonium , C. pygmaeus , and C. omiltemanus in the Sierra Madre del Sur of Guerrero. It may overlap with C. mexicanus in eastern Guerrero and western Oaxaca ( Fig. 6 ).

Figures

FIG. 36.—Subadult Craugastor saltator (left, UTA A-66120, SVL ¼ 14.5 mm) from area above Corral de Bravo, Guerrero, Mexico, 2560–2590 m; female holotype (right, FMNH 100166, SVL ¼ 44.0 mm) from Omiltemi, Guerrero, Mexico. A color version of this figure is available online.

FIG. 6.—Distribution of Craugastor mexicanus, C. montanus, C. pygmaeus, and C. saltator in Mexico and Guatemala. Dots inside symbols indicate individuals used in the molecular analyses in this study. Relevant type localities are indicated by text and arrows.

FIG. 3.—Concatenated Maximum Likelihood analyses of two mitochondrial (12S and 16S) and two nuclear (RAG1 and TYR) gene fragments sequenced from the Craugastor mexicanus series (total of 2230 base pairs). Node values correspond to bootstrap support from Maximum Likelihood analysis and posterior probabilities from a Bayesian analysis of the same data set, respectively. Support values are not reported for nodes that had,50/0.50. NS indicates no support in the Bayesian analysis for a depicted relationship. Locality abbreviations are as follows: COL ¼ Colima, HID ¼ Hidalgo, GRO ¼ Guerrero, JAL ¼ Jalisco, MEX ¼ Estado de México, OAX ¼ Oaxaca, PUE ¼ Puebla, and VER ¼ Veracruz.

FIG. 4.—Maximum Likelihood analyses of mitochondrial DNA (mtDNA) markers sequenced from the Craugastor mexicanus series (total of 1047 base pairs). Black circles indicate nodes receiving bootstrap support values.90 from the Maximum Likelihood analysis and 0.90 posterior probabilities in corresponding Bayesian analyses. Where posterior probabilities were.0.90 but Maximum Likelihood bootstrap support was,90, a number indicates the bootstrap support. NS indicates no support in the Bayesian analysis for a depicted relationship. Locality abbreviations are as follows: COL ¼ Colima, HID ¼ Hidalgo, GRO ¼ Guerrero, JAL ¼ Jalisco, MEX ¼ Estado de México, OAX ¼ Oaxaca, PUE ¼ Puebla, and VER ¼ Veracruz.

FIG. 10.—Difference in ontogenetic trajectories between select largebodied (Craugastor mexicanus, C. omiltemanus, C. saltator) and smallbodied species (C. hobartsmithi, C. pygmaeus) of the C. mexicanus series as evidenced by reduced-major axis regression of size-correlated shape axes with log-centroid size following Sidlauskas et al. (2011).

FIG. 11.—Ossification levels within the Craugastor mexicanus series compared with body size (estimated as log centroid size). Ossification scores are based on the six-stage ontogenetic sequence described in Table 3.