Craugastor montanus ( Taylor 1942 )

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 : 29

Craugastor montanus ( Taylor 1942)

Microbatrachylus montanus Taylor 1942:67 . Holotype female ( USNM 115507 ) from ‘‘Mount Ovando, Chiapas, Mexico.’’ [Examined] .

Eleutherodactylus sartori Lynch 1965:10 . [Replacement name].

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

Diagnosis. —Based on holotype ( Fig. 1E ). Aspecies of Craugastor distinguished by the following combination of characters: (1) moderate adult size (holotype, SVL ¼ 24.5 mm); (2) ossification of most of skeleton in adults; (3) presence of posterolateral projection of frontoparietal; (4) presence of vomerine odontophores; (5) presence or absence of raised tubercles on eyelids; (6) supratympanic fold moderate to poorly developed; (7) face flank barred with or without canthal stripe, 1–2 particularly dark bars below eye; (8) one (or two fused) postrictal tubercles; (9) gular region with pale spotting; (10) dorsal surface blotched or unicolored pale; diffuse interorbital bar, small suprascapular spots; sometimes with two dark rump spots (11) middorsal ridge present; (12) dorsum smooth with only few fine tubercles; (13) body flank darker anteriorly (post axillary), slightly shagreened to smooth; (14) inguinal gland present and axillary gland present in adults; (15) when leg adpressed to body, heel reaches snout tip or beyond; (16) outer tarsal ridge with 0–2 small and round tubercles close to heel, no raised fringe; (17) finger and toe tips round, finger tips slightly or not expanded, toe tips expanded; (18) inner metatarsal tubercle larger than outer metatarsal tubercle.

Comparisons. — Craugastor montanus can be differentiated from C. candelariensis , C. cueyatl , C. hobartsmithi , and C. portilloensis by equal sizes of the inner and outer metatarsal tubercles (unequal sizes in C. montanus ). It can be differentiated from C. bitonium and C. pygmaeus by the absence of a posterolateral projection of the frontoparietal (present in C. montanus ). It can be differentiated from C. polaclavus and C. rubinus by the absence of vomerine odontophores (present in C. montanus ). It can be differentiated from C. mexicanus , C. omiltemanus , and C. saltator by the general shape of its skull ( Fig. 12 ). It can be differentiated from C. mexicanus by the condition of supratympanic folds in adults; moderate to poorly developed in C. montanus versus developed in C. mexicanus . It can be differentiated from C. omiltemanus by ventral skin texture in life; smooth to granular in C. montanus versus areolate in C. omiltemanus . It can be differentiated from C. saltator by relative leg length; crus 53–59% SVL in C. montanus versus 62–73% SVL in C. saltator .

Description. —In previous literature, described as moderately sized (males average 16.2 mm SVL, females average 24.0 mm SVL); Finger Ishorter than Finger II; three palmar tubercles; testes black; inner metatarsal tubercle larger than outer metatarsaltubercle ( Lynch 2000). Lynch (2000:133) redescribed C. montanus (as E. sartori ) owing to ‘‘errors in Taylor’s (1942) original description that were repeated by Lynch (1965, 1970)’’.

Distribution. —This species is known from intermediate to high elevations (~ 2000 m) of the Sierra Madre de Chiapas in the state of Chiapas, Mexico ( Lynch 2000), and adjacent regions of the Department of San Marcos, Guatemala ( Crawford and Smith 2005). This region contains a complex mixture of dry forests, mixed forests, cloud forests, and pine– oak forests.

Phylogenetics. —In the concatenated analysis, C. montanus was recovered as the sister taxon of all other members of the C. mexicanus series (ML ¼ 66, BAYES ¼ 0.99; Fig. 3 ). It also had this placement in the mtDNA-only analysis ( Fig. 4 ), but not in the nDNA analysis where it was found with weak support to be the sister taxon of a clade containing all taxa except C. mexicanus and C. omiltemanus (ML ¼ 33, BAYES ¼ 0.73; Fig. 5 ). This differs from the phylogenetic placement of C. montanus (as E. sartori ) in the nDNA-only analysis of Crawford and Smith (2005). In terms of genetic distances ( Table 4 ), C. montanus was most similar to C. polaclavus (5.7%) followed by similarity with C. mexicanus (6.1%).

Remarks. —The skull of C. montanus is similar to C. hobartsmithi and C. pygmaeus , with more posteriorly placed anterior suture of the frontoparietal and prootic than in other species. The skull of C. montanus was also described by Lynch (2000) as E. sartori . Lynch (1965) created the neonym, Eleutherodactylus sartori , because Eleutherodactylus montanus was preoccupied by a West Indian species. This is the most southernly distributed species in the C. mexicanus series. Craugastor montanus likely co-occurs with C. pygmaeus .

The type locality of C. greggi ( Bumzahem 1955) is Volcan Tajumulco in San Marcos, Guatemala near where we sampled C. montanus for our molecular analysis ( Fig. 6 ). Although C. greggi was placed in the C. laticeps series of Hedges et al. (2008), it is allied to the C. mexicanus series by having Finger Ishorter than Finger II. This affinity was noted in the original description: ‘‘ Eleutherodactylus greggi seems to agree most closely with the member of the Eleutherodactylus mexicanus group...’’ ( Bumzahem 1955:119). However, C. greggi was differentiated from C. montanus (¼ E. sartori ) by Lynch (2000) on the basis of fusion between the last presacral vertebrae and sacrum (not fused in C montanus ). Nonetheless, our preliminary examinations of the holotype of C. greggi ( Fig. 28 ) and collections from the Sierra de Chiapas suggest that future research is needed to confirm C. greggi can be differentiated from C. montanus because the taxa are united by multiple characters including (but not limited to) adult body size, presence of vomerine odonotophores, presence of posterolateral projection of frontoparietal, gular region with pale spotting, finger lengths, toe lengths, unequal sizes of the inner and outer metatarsal tubercles, and geographic distribution.

Figures

FIG. 1.—Male holotype of Eleutherodactylus hobartsmithi Taylor (A, FMNH 100114, SVL ¼ 14.4 mm); female holotype of Leiuperus mexicanus Brocchi (B, MNHNP 6318, SVL ~ 40 mm); male holotype of Microbatrachylus oaxacae Taylor (C, FMNH 100001, SVL ¼ 18.1 mm); male holotype of Microbatrachylus lineatissimus Taylor (D, FMNH 100036, SVL ¼ 20.0 mm); female holotype of Microbatrachylus montanus Taylor (E, USNM 115507, SVL ¼ 27.0 mm); female holotype of Eleutherodactylus pygmaeus Taylor (F, UIMNH 16125, SVL ¼ 17.0 mm); female holotype of Microbatrachylus albolabris Taylor (G, FMNH 100071, SVL ¼ 16.5 mm); male holotype of Microbatrachylus minimus Taylor (H, FMNH 100323, SVL ¼ 15.0 mm); female holotype of Microbatrachylus imitator Taylor (I, USNM 115508, SVL ¼ 14.2 mm); male lectotype of Syrrhaphus omiltemanus Günther (J, BMNH 1947.2.16.62, SVL ¼ 19.8 mm); female lectotype of Hylodes calcitrans Günther (K, BMNH 1947.2.16.47, SVL ¼ 34.9 mm); female holotype of Eleutherodactylus saltator Taylor (L, FMNH 100166, SVL ¼ 44.0 mm). Symbols correspond to current taxonomic assignments (square ¼ C. hobartsmithi, triangle ¼ C. mexicanus, crossedsquare ¼ C. montanus, pentagon ¼ C. omiltemanus, circle ¼ C. pygmaeus, rotated-triangle ¼ C. saltator). A color version of this figure is available online.

FIG. 12.—Skull shape variation within the Craugastor mexicanus series as depicted by principal components analysis of 14 geometric morphometric landmarks (Fig. 10). The first 7 principal components explained ~75% of the variance. The second and third principal components are depicted because they maximized differences between large-bodied and small bodied species.

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. 5.—Maximum Likelihood analysis of nuclear DNA (nDNA) markers sequenced from the Craugastor mexicanus series (total of 1183 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, GRO ¼ Guerrero, JAL ¼ Jalisco, MEX ¼ Estado de México, OAX ¼ Oaxaca, PUE ¼ Puebla, and VER ¼ Veracruz.

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. 28.—Female holotype of Craugastor greggi (FMNH 20876, SVL ¼ 36.0 mm) of the C. laticeps series (sensu Hedges et al. 2008) from Volcan Tajumulco, near San Marcos, Guatemala, in dorsal (left) and ventral (right) views. Images courtesy of the Field Museum of Natural History. A color version of this figure is available online.