Crotalus campbelli, 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 : 486-489

Crotalus campbelli sp. nov.

Figs. 7–8 , Table 3

Crotalus triseriatus — Boulenger (1896): 581 (in part).

Crotalus triseriatus armstrongi — Dorcas (1992): 87 (in part).

Crotalus triseriatus armstrongi — Bryson et al. (2011): 699 (in part). Crotalus triseriatus armstrongi — Reyes-Velasco et al. (2009): 118.

Crotalus armstrongi — Reyes-Velasco et al. (2013): 528 (in part).

Holotype. Adult female (KU 73649) collected 25 October 1962 by Percy L. Clifton (field number PLC 3216) in the Sierra de Cuale, 9 km N El Teosinte, municipality of Talpa de Allende, state of Jalisco, Mexico.

Paratypes. 5 specimens. Mexico: JALISCO: same collection data as holotype (KU 73650). Las Playitas, Las Joyas, Sierra de Manantlán, municipality of Autlán de Navarro; collected September 1985 by E. Fanti-Echegoyen ( UTA R- 16352). Las Joyas, Sierra de Manantlán, municipality of Autlán de Navarro; collected September 1985 by E. Fanti-Echegoyen ( UTA R- 16353). ca. 25 km SE Autlán, ca. 2.1 km (by dirt road) SE Manantlán; collected 27 July 1975 by G. M. Tilger and R. G. Arndt ( AMNH R- 113191). Lago de Juanacatlán, Sierra de Mascota, municipality of Mascota (20°37'30.94"N, 104°43'36.30"W; 2009 m asl; WGS84); collected 10 April 2011 by R. W. Bryson Jr. and M. Torocco ( MZFC 28669).

Diagnosis. Crotalus campbelli can be distinguished from all members of the C. triseriatus species group except C. armstrongi by the combination of the following characters: (1) presence of intercanthals, (2) infrequently divided upper preocular (9.1% of the time), (3) 150–154 ventrals in males, 147–152 in females, (4) 31–32 subcaudals in males, 22–26 in females, (5) small rattle (proximal rattle width 11.0–14.6% of head length), (6) long tail (9.1–11.0% of total body length in males, 7.5–8.9% in females), (7) pale interspaces between dorsal and lateral blotches, (8) heavy venter mottling, (9) dark proximal rattle and underside of tail, and (10) usually a single large anterior intercanthal. Crotalus campbelli can be distinguished from C. armstrongi based on higher mean number of ventrals (152 in males and 149 in females vs. 141 and 144), higher mean number of subcaudals in males (31 vs. 28), less frequently divided upper preocular (9.1% vs. 14.3%), proportionately longer tail in males (10.3% of total body length vs. 9.7%), smaller mean proximal rattle width (13.0% of head length vs. 14.0%), higher mean number of dorsal blotches (48 vs. 42), and higher number of tail bands (mode of 9 vs. 6).

Crotalus campbelli is most similar to members of the C. triseriatus group distributed along the Trans-Mexican Volcanic Belt, including C. pusillus , C. armstrongi , C. triseriatus , and C. tlaloci . Crotalus campbelli is distinguished from C. pusillus by possessing intercanthals and an infrequently divided upper preocular, from C. tlaloci by having an infrequently divided upper preocular, variable number of intercanthals, fewer ventrals (in females, 147–152 vs. 156–165; in males, mean number 152 vs. 156), lower mean number of subcaudals in females (24 vs. 28), proportionately shorter tail in females (8.2% of total length vs. 9.2%), and higher mean number of dorsal blotches (48 vs. 43), and from C. triseriatus by a higher number of ventrals (in males, 150–154 vs. 134–146; in females, mean number higher: 149 vs. 142), higher mean number of subcaudals in males (31 vs. 28), proportionately smaller proximal rattle (13.0% of head length vs. 15.8%), and by having pale interspaces between dorsal and lateral blotches. Crotalus campbelli is most similar in general appearance to C. armstrongi , but can be distinguished from this species by characters mentioned above. Half of the specimens of C. campbelli also possess a single, large anterior intercanthal. This scale arrangement is rarely seen in C. armstrongi and C. triseriatus . Crotalus campbelli is easily distinguished from C. ravus by the lack of large head plates in the parietal region.

Description of the holotype. Rostral broader than high (3.7 x 2.6 mm); two internasals, in medial contact, slightly wider than long, convex through center of scale; two canthals, large, convex, circular, separated by a single, large, convex intercanthal bordered anteriorly by three small scales; four large intersupraoculars posterior to intercanthals, followed by multiple rows of small intersupraoculars. Nostril centered between prenasal and postnasal scales, prenasal larger than postnasal and wrapping around anterior aspect of rostrum; single loreal. Loreal pit midway between eye and naris, below line from middle of eye to naris, bordered by single prelacunal, postlacunal, lower preocular; prelacunal contacting second and third supralabials and two prefovials; three prefovials; 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, upper twice as large as lower. Supralabials 13/13; infralabials 11/12; first infralabials in medial contact posterior to triangular mental; genials together resemble wings. Midbody dorsal scale rows 23–25; preventral single; ventrals 152; subcaudals 22, nondivided; eight rattle fringe scales; tail bearing three rattle segments.

Ground color, in preservative, light brown with 54 dark dorsal body blotches, irregularly edged in black with a very thin light outer edge on most blotches, blotches wider than long, interspaces between blotches 1–2 scales long; smaller, vertically elongated auxiliary blotches evident laterally below the dorsal blotches, often separated from the dorsal blotches by white scales. Head marked with parallel rows of small irregular blotches across prefrontals, supraoculars, and much of the occipital area, terminated by paired occipital blotches; supralabials and infralabials ground color white, stippled with dark brown spots; distinct dark postocular stripe, uniform in width, extending from posterior of eye to above the angle of the mouth and then downwards to jawline; postocular stripe bordered by a darker band on both dorsal and ventral margins, dorsally a narrow region of light brown extends from the posterior axis of the eye along the dorsal margin of the postocular band, ventral to the postocular band is a region of white with brown stippling, supralabial 8 is nearly completely white, with moderate stippling but no postocular band, supralabials 8–13 are divided by the postocular band; two large dark brown blotches are on the borders of supralabials 5–7; scale margins of infralabials with dark brown regions making for a series of dark bands, bands do not extend beyond infralabials; gular scales stippled with no pattern; ventral scutes stippled, more heavily on posterior half of scales, with total stippling intensifying past midbody; distal 1/3 ventral scutes become dark brown with a lighter band along the midline, continuing to the vent. Subcaudal scales dark brown to black; eight dark brown tail bands; proximal rattle black, distal sections brown.

Color in life. Color in life within the type series is only known for one paratype (MZFC 28669), shown in Fig. 8 .

Variation. Three of the six specimens lack a single, large anterior intercanthal. The holotype, KU 73649, has a single large intercanthal bordered anteriorly by three small, seemingly anomalous scales ( Fig. 7 ). Similarly, UTA R-16353 has paired anterior intercanthals separated by a small but elongated scale. The third specimen, AMNH R- 113191, has paired anterior intercanthals. The single juvenile (AMNH R- 113191) has a cream-colored proximal rattle and pale-colored tail ventrally. Variation in meristic, morphometric, and color pattern characters within the type series is listed in Table 3 .

Etymology. The specific epithet is a patronym honoring Jonathan A. Campbell for his many years of field research on Mexican rattlesnakes and for his decades of unwavering support to students of Mexican herpetology.

Habitat and distribution. Crotalus campbelli is found in rocky open breaks within montane forest ( Fig. 9 ) along the far western regions of the Trans-Mexican Volcanic Belt. Much of this forest is covered with remnant patches of cloud forest ( Ponce-Reyes et al. 2012). This species is known from western Jalisco and the Sierra de Manantlán in southern Jalisco/northwestern Colima. A narrow low-elevation valley appears to separate the range of C. campbelli from C. armstrongi to the east ( Fig. 3 ).

Figures

FIGURE 3. Geographic distribution of species in the Crotalus triseriatus species group distributed across the Trans-Volcanic Belt. Circled dots indicate type localities. Arrows point to low-elevation depressions that are probable barriers to gene flow. Names of species reflect our proposed taxonomy.

FIGURE 7. Lateral and dorsal view of the holotype of Crotalus campbelli sp. nov. (KU 73649).

FIGURE 8. Crotalus campbelli sp. nov. in life, (a) MZFC 28669, paratype from the Sierra de Mascota, Jalisco; and (b) specimen in the wild, Sierra de Manantlán, Colima.

FIGURE 9. Humid montane forest habitat of Crotalus campbelli sp. nov. at the paratype localities of (a) Sierra de Mascota, Jalisco; and (b) Sierra de Manantlán, Colima.