Crotalus tlaloci, Bryson, Robert W., Linkem, Charles W., Dorcas, Michael E., Lathrop, Amy, Jones, Jason M., Alvarado-Díaz, Javier, Grünwald, Christoph I. & Murphy, Robert W., 2014

Bryson, Robert W., Linkem, Charles W., Dorcas, Michael E., Lathrop, Amy, Jones, Jason M., Alvarado-Díaz, Javier, Grünwald, Christoph I. & Murphy, Robert W., 2014, Multilocus species delimitation in the Crotalus triseriatus species group (Serpentes: Viperidae: Crotalinae), with the description of two new species, Zootaxa 3826 (3), pp. 475-496 : 483-486

Crotalus tlaloci sp. nov.

Figs. 4–5 , Table 3

Crotalus triseriatus triseriatus — Campbell & Lamar (2004): 527 (Map 90), 593 (in part). Crotalus triseriatus triseriatus — Flores-Villela & Hernández-García (1989): 16. Crotalus triseriatus triseriatus — Pérez-Ramos et al. (2000): 34.

Crotalus triseriatus triseriatus — Flores-Villela & Hernández-García (2006): 270.

Holotype. Adult female ( MZFC 3666) collected 20 June 1986 by Efrain Hernández-García in “Los Llanos” (18°36’N, 99°37’W; 2200–2300 m above sea level; asl hereafter), 10 km by road from Taxco to Tetipac, Sierra de Taxco, municipality of Tetipac, state of Guerrero, Mexico.

Paratypes. 11 specimens. MEXICO: GUERRERO: Cerro del Huizteco, Sierra de Taxco, municipality of Taxco (18°36'N, 99°36'W; 2300–2520 m asl); collected 22–23 August 1986 by E. Hernández-García ( MZFC 3664–3665). “Arroyo las Damas”, Sierra de Taxco, municipality of Tetipac (18°38'N, 99°37'W; 1600–1850 m asl); collected by E. Hernández-García ( MZFC 3666). ESTADO DE MÉXICO: Acatitlán, municipality of Valle de Bravo; collected 7 September 1988 by T. Hentschel-Maida ( MZFC 4324). Los Álamos, municipality of Valle de Bravo (19°11'20.2"N, 100°03'57.2"; 2201 m asl; NAD27 Mexico); collected 23 May 2008 by J. Jones, C. I. Grünwald, and R. W. Bryson Jr. (HINIRENA 725–726). Los Álamos, municipality of Valle de Bravo (19°11'20.2"N, 100°03'57.2"; 2201 m asl; NAD27 Mexico); collected 22 July 2009 by R. W. Bryson Jr. and M. Torocco ( MZFC 25114–25115). MORELOS: Km 12, Carr. Cuernavaca-Ocuilán, municipality of Cuernavaca; collected 17 March 1990 by M. Torres Chávez ( MZFC 4657). Carr. Cuernavaca-Ocuilán, near state border, municipality of Cuernavaca (18°58'54.43"N, 99°18'20.43"W; 2268 m asl; WGS84); collected 13 June 2009 by J. Jones, C. I. Grünwald, and R. W. Bryson Jr. ( MZFC 25111). MICHOACÁN: N Arroyo Seco, municipality of Aporo (19°40'28.3"N, 100°22'35.8"W; 2463 m asl; NAD27 Mexico); collected 24 May 2008 by J. Jones, C. I. Grünwald, and R. W. Bryson Jr. (HINIRENA 724).

Diagnosis. Crotalus tlaloci can be distinguished from all members of the C. triseriatus species group by the combination of the following characters: (1) presence of intercanthals, (2) undivided upper preocular, (3) 152–164 ventrals in males, 156–165 in females, (4) 27–33 subcaudals in males, 22–32 in females, (5) small rattle (proximal rattle width 11.1–14.5% of head length), (6) long tail (8.9–11.3% of total body length in males, 8.0–10.7% in females), (7) usually two pairs of symmetrical, similarly sized intercanthals, and (8) dark postocular stripe that noticeably narrows before reaching the posterior of the eye.

Crotalus tlaloci is most similar to species of the C. triseriatus group distributed along the Trans-Mexican Volcanic Belt. Crotalus tlaloci is distinguished from these species by the presence of intercanthals (lacking in C. pusillus ), undivided upper preocular (divided 14.3% of the time in C. armstrongi and 9.4% of the time in C. triseriatus ), high number of ventrals (overlapping with C. pusillus , but mean number in C. tlaloci higher than C. pusillus : 156 vs. 154, respectively), high number of subcaudals (mean number in females higher than in C. pusillus , C. armstrongi , and C. triseriatus : 28 vs. 26, 24, and 24; in males, higher than in C. armstrongi and C. triseriatus : 30 vs. 28 in both), proportionately small proximal rattle (mean width smaller than in C. armstrongi and C. triseriatus : 12.8% of head length vs. 14.0% and 15.8%), and proportionately longer tail (mean length in females higher than in C. pusillus , C. armstrongi , and C. triseriatus : 9.2% of total length vs. 8.6%, 8.3%, and 8.3%). Most specimens (10/12) possess two pairs of symmetrical, similarly sized intercanthals, creating the appearance of butterfly wings. Of the 100 specimens in the C. triseriatus group that we examined, this symmetrical paired arrangement of intercanthal scales in the prefrontal region (“butterfly wings”) was observed in only one other specimen ( C. armstrongi , CNAR 4498). Crotalus tlaloci also possess a dark postocular stripe that noticeably narrows before reaching the posterior of the eye. In C. pusillus , C. armstrongi , and C. triseriatus , the postocular stripe is generally of uniform width, although on rare occasions in C. pusillus and C. armstrongi it tapers slightly before reaching the eye.

Description of the holotype. Rostral broader than high (4.0 x 2.8 mm); two internasals, in medial contact, wider than long, rectangular, convex through center of scale; two canthals, large, convex, separated by two pairs of square intercanthals; four large intersupraoculars posterior to intercanthals, followed by multiple rows of small intersupraoculars. Naris centered between prenasal and postnasal scales, prenasal larger than postnasal and wrapping around anterior aspect of rostrum; two loreals, lower larger; small upper loreal between canthal, internasal, postnasal, and lower loreal. Loreal pit midway between eye and naris, below line from middle of eye to naris, bordered by single prelacunal, postlacunal, lower preocular, and lower loreal; prelacunal contacting second and third supralabials and a single prefovial (two prefovials on left); two prefovials on right, three on left; single postfovial contacting postlacunal, lower preocular, first subocular, and fourth supralabial. Two preoculars, upper large and convex, contacting supraocular and canthal, lower preocular thin and long; three suboculars, anterior largest and in contact with fourth supralabial; three interoculabials posterior to anterior subocular; two postoculars, dorsal twice as large as ventral. Supralabials 12/12; infralabials 13/13; first infralabials in medial contact posterior to triangular mental; genials together resemble a heart shape. Midbody dorsal scale rows 22–23; preventral single; ventrals 162; subcaudals 27, last subcaudal row divided into three scales; nine rattle fringe scales; tail bearing four rattle segments.

Coloration significantly faded in preservative with body blotches and bands difficult to discern from ground color. Ground color gray; occasional black speckling along body. Blotches faded to ground coloration in many places, approximately 38 blotches visible. Blotches bordered by lighter coloration than ground color, also heavily faded. Ground color of head gray, heavily stippled with dark brown throughout dorsal and anterior lateral regions of the head; rostral and supralabials 1–4 heavily stippled, supralabials 5–7 with lighter stippling in the scale center; infralabials with brown stippling on scale margins with white scale centers, extending to mouth; gular scales lightly stippled, decreasing in frequency towards the midline of the head. Ventral scutes evenly stippled, increasing in intensity posterior to mid-body with scutes becoming almost completely brown by the tail. Six dark tail bands, the first two bordered by white bands; caudal scales dark brown. Proximal rattle black, distal sections brownish.

Color in life. Color in life varies ( Fig. 5 ), with most specimens vibrantly colored, although one is darkly pigmented (MZFC 25111; Fig. 5 ). The holotype is known only from the preserved specimen.

Variation. Two specimens lack symmetrical paired intercanthals. The first, HINIRENA 725, has one pair of anterior intercanthals but only a single large posterior intercanthal. The second, HINIRENA 724, has one pair of anterior intercanthals, one of which is subdivided, followed by a single large posterior intercanthal. Supralabials in five specimens (MZFC 3664, 3665, 4657, 25111, 25114) are horizontally divided. This split was in the 7th, 8th, or 9th supralabial and when present, occurred in supralabials on both sides of the head. Juveniles (MZFC 3664, 3665, 3667, HINIRENA 726) have cream-colored proximal rattles and pale-colored tails ventrally, typical of juveniles in other species in the C. triseriatus group. Variation in meristic, morphometric, and color pattern characters within the type series is listed in Table 3 .

Etymology. This species is named for Tláloc, the Aztec god of rain.

Habitat and distribution. Crotalus tlaloci inhabits open areas in cloud forest and humid oak-pine forest along the lower slopes of the Trans-Mexican Volcanic Belt. Although one record in the Sierra de Taxco (“Arroyo las Damas”) is at 1850 m ( Flores-Villela & Sánchez-H 2003), most records are at around 2000–2400 m asl. This species is known from the states of Guerrero, Estado de México, Michoacán, and Morelos, and may range into western Puebla. The vegetation where C. tlaloci is found is characterized by broad-leaf oaks, such as Quercus candicans and Q. laurina , and dense undergrowth ( Fig. 6 ), and is distinctly different than the drier pine-oak forest inhabited by C. triseriatus . The distribution of C. tlaloci overlaps the ranges of two alligator lizards, Barisia herrerae Zaldívar-Riverón & Nieto-Montes de Oca 2002 and B. rudicollis (Wiegmann 1828) (Zaldívar-Riverón & Nieto-Montes de Oca 2002). Interestingly, both of these alligator lizards occur in similar humid forest habitat at elevations of 2000–2500 m asl, and appear ecologically isolated from B. imbricata (Wiegmann 1828) , which inhabits the surrounding drier pine-oak forest (Zaldívar-Riverón & Nieto-Montes de Oca 2001, 2002). Specimens of C. tlaloci are generally found in rocky open forest breaks and edges of cloud or humid oak-pine forest. However, we found an adult gravid female and juvenile (HINIRENA 725, 726) under logs in a clearing relatively devoid of rocky habitat.

Figures

FIGURE 4. Lateral and dorsal view of the holotype of Crotalus tlaloci sp. nov. (MZFC 3666). The symmetrical paired arrangement of intercanthal scales, shown here in gray, create the appearance of butterfly wings in the prefrontal region.

FIGURE 5. Crotalus tlaloci sp. nov. in life, (a) MZFC 25114, paratype from Valle de Bravo, Estado de México; (b) HINIRENA 725, paratype from Valle de Bravo, Estado de México; (c) MZFC 25111, paratype from Cuernavaca-Ocuilán highway, Morelos; and (d) HINIRENA 724, paratype from Arroyo Seco, Michoacán.

FIGURE 6. Humid oak-pine forest habitat of Crotalus tlaloci sp. nov. at the paratype localities of (a) Los Álamos, near Valle de Bravo, Estado de México; and (b) Arroyo Seco, Michoacán.