Craugastor portilloensis, Jameson & Streicher & Manuelli & Head & Smith, 2022

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 : 33-34

Craugastor portilloensis sp. nov.

Holotype. — UTA A-62393 (field ID: JAC 21431; Fig. 32 ), subadult female collected by E.N. Smith and colleagues in Portillo del Rayo , Distrito San Pedro Pochutla, Sierra Madre del Sur , Oaxaca, Mexico, 15.9794448N, 96.5166678W, 1550 m, 1 October 2001 .

Paratypes (4). —MZFC-HE-35580 and UTA A- 66095, juvenile males. MZFC-HE- 35581 subadult female, and UTA A- 66096 subadult male. All collected at the type locality between 1550 and 1585 mon 24 September 2001 by E.N. Smith and colleagues .

Diagnosis. —A species of Craugastor distinguished by the following combination of characters: (1) small adult size (maximum SVL ¼ 11.4 mm); (2) reduced ossification of skeleton in adults relative to other members of the series, lacking ossification of any skeletal elements beyond Stage 2 ( Table 3 ); (3) presence of posterolateral projection of frontoparietal; (4) absence of vomerine odontophores; (5) presence or absence of raised tubercles on eyelids; (6) supratympanic fold absent or poorly developed; (7) face flank darker than dorsum, faintly barred lips, snout–nostril– canthal–supratympanic stripe; (8) one or two postrictal tubercles; (9) gular region with pale spotting; (10) dorsal surface unicolored pale, diffuse interorbital bar, sometimes with two dark rump spots; (11) with or without a middorsal ridge; (12) dorsum smooth or with scattered fine tubercles; (13) body flank has dark supratympanic stripe extending toward lower mid-flank, smooth, very few small tubercles; (14) inguinal glands present and axillary glands absent in adults; (15) when leg adpressed to body, heel reaches between eye and slightly past snout; (16) outer tarsal ridge smooth or with 1–3 extremely small, flat, and round tubercles, no raised fringe; (17) finger and toe pads round, finger tips not expanded, toe tips slightly expanded; (18) similar sizes of inner and outer metatarsal tubercles.

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Comparisons. — Craugastor portilloensis can be differentiated from C. candelariensis , C. mexicanus , C. montanus , C. omiltemanus , and C. saltator by the presence of vomerine odontophores (absent in C. portilloensis ). It can be differentiated from C. bitonium , C. hobartsmithi , and C. pygameus by the absence of a posterolateral projection of the frontoparietal (present in C. portilloensis ). It can be further differentiated from C. pygmaeus by the absence of a canthal mask (present in C. portilloensis ). It can be differentiated from C. cueyatl and C. polaclavus by metatarsal tubercles of unequal size (equal in C. portilloensis ). It can be differentiated from C. rubinus by relative finger lengths of IV ¼ II (IV> II in C. portilloensis ).

Description of holotype. — Holotype small female (SVL ¼ 11.4 mm); snout rounded and short (0.8 mm naris–snout; 6% SVL); short eye–nostril distance (1.1 mm; 9.8% SVL); tympanum 0.8 mm (6.8% SVL); no supratympanic fold; small shoulder tubercle; finger length formula III <IV <II <I; single flat palmar tubercle; single flat prepollical tubercle; subarticular tubercles present on all fingers; supernumerary tubercles not present on hand; toe length formula IV <III <V <II <I; inner metatarsaltubercle and outer metatarsaltubercle equal size; subarticular tubercles present on all toes; supernumerary tubercles present on plantar surface; right leg removed for genetic analysis; small supracloacal fold; dark mask extending from snout through eye and past tympanum onto flanks ( Fig. 32 ; coloration also in paratypes). Some bands present on arms and legs.

Variations in paratypes. —Body sizes in SVL 8.7 mm (MZFC-HE-35580), 8.4 mm (UTA A-66095), 12.1 mm (MZFC-HE-35581), 12.6 mm (UTA A-66096); eye–nostril distance 10–11% SVL; tympanic ratios 7%.

Etymology. —The name is an abbreviated allusion to the type locality near the town of Portillo del Rayo and the Latin suffix - ensis meaning place.

Distribution. —Intermediate elevations in the foothills of the Sierra Madre del Sur in Oaxaca 1550–1585 m ( Fig. 8 ). These habitats consist of mixed tropical dry and temperate sierra forests.

Phylogenetics. —In the concatenated analysis, Craugastor portilloensis is the sister taxon to a clade of small-bodied species ( C. bitonium , C. candelariensis , C. cueyatl , C. hobartsmithi , C. polaclavus , C. pygmaeus , and C. rubinus ), but with low branch support (ML ¼ 53, BAYES ¼ 66; Fig. 3 ). It occupies the same phylogenetic placement in the mtDNA-only data set ( Fig. 4 ), but in the nDNA-only data set is the sister taxon of a clade including ( C. bitonium , C. cueyatl , C. hobartsmithi , C. pygmaeus , and C. rubinus ) with moderate support in the Bayesian analysis (ML ¼ 43, BAYES ¼ 0.78; Fig. 5 ). In terms of genetic distances ( Table 4 ), C. portilloensis was most similar to C. montanus (5.7%), followed by similarity to C. polaclavus (5.8%).

Remarks. —The skull of C. portilloensis is similar to C. mexicanus , C. omiltemanus , and C. saltator , with a more anteriorly placed anterior suture of frontoparietal and prootic than in other species. We dissected all specimens of C. portilloensis ; males possess pigmented testes and females unpigmented ovaries. This species likely co-occurs with C. candelariensis , C. polaclavus , and C. pygmaeus in southcentral Oaxaca ( Figs. 6 and 8 ). It was collected in sympatry with C. polaclavus at the type locality of Portillo del Rayo, Oaxaca, Mexico ( Fig. 8 ).

Figures

FIG. 32.—Female holotype of Craugastor portilloensis (UTA A-62393, SVL ¼ 11.4 mm) from Portillo del Rayo, Oaxaca, Mexico, 1550 m. The specimen’s leg was removed for genetic analysis. A color version of this figure is available online.

FIG. 8.—Distribution of Craugastor hobartsmithi, C. cf. hobartsmithi, C. omiltemanus and six new species from Mexico. Dots inside symbols indicate individuals used in the molecular analyses in this study. Inset depicts region of Oaxaca where three of the new species exist in near sympatry. A question mark indicates uncertain georeferencing. 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. 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.