Crotalus mictlantecuhtli, Carbajal-Márquez & Cedeño-Vázquez & Martínez-Arce & Neri-Castro & Machkour- M’Rabet, 2020

Carbajal-Márquez, Rubén Alonso, Cedeño-Vázquez, José Rogelio, Martínez-Arce, Arely, Neri-Castro, Edgar & Machkour- M’Rabet, Salima C., 2020, Accessing cryptic diversity in Neotropical rattlesnakes (Serpentes: Viperidae: Crotalus) with the description of two new species, Zootaxa 4729 (4), pp. 451-481 : 462-465

Crotalus mictlantecuhtli sp. nov.

Figs. 5–6 , Table 3

Crotalus simus — Savage et al. (2005): 370; Wüster et al. (2005): 1097 ( Fig.1 ), 1103; Heimes (2016): 470, 518 (Map 186).

Crotalus simus simus— Campbell & Lamar (2004): 584 (Map 109), 586.

Crotalus durissus durissus — Klauber (1941): 64, 65; Smith & Taylor (1950): 348; Armstrong & Murphy (1979): 10; McCranie (1993): 577.2 (Map 1), 577.5.

Holotype. Adult male ( SDNHM-22416 ) collected on 27 May of 1934 by W. A. King in Veracruz city (19.18833 °, -96.14000°; 13 m above sea level; asl hereafter), state of Veracruz, Mexico.

Paratype. Adult male ( SDNHM-24026 ) collected 14 July of 1935 by W. A. King in Tierra Blanca (18.44981°, -96.35995°; 68 m asl), municipality of Tierra Blanca, state of Veracruz, Mexico.

Diagnosis. A rattlesnake belonging to the Crotalus durissus species complex, characterized as other species by a prominent vertebral process and conspicuous scale tuberculations. Crotalus mictlantecuhtli is not sympatric with any congeners, but its range closely approaches those of C. simus -Isthmus-Chiapas and C. tzabcan . Crotalus mictlantecuhtli can be distinguished from all members of the Crotalus durissus species complex by exclusive combination of the following characters: paravertebral stripes with three scale rows, commonly paravertebral stripes with light center, presupraloreal scale absent, postloreal scale absent, usually postsupraloreal scale absent, contact between lacunal and supralabial scales in 68% (n =34) of specimens, postocular stripes of 3.0–3.5 scales width, with light center, contact between paravertebral stripes and supraocular scales in 97% (n =34) of specimens, and dark prefrontal bar interrupted.

Comparisons. Crotalus mictlantecuhtli is closely related to species of the northern clade ( C. culminatus ) of the Crotalus durissus species complex, and differ from them by having 168–176 (mode=170) ventral scales in males, 169–178 (mode=174) females (vs. 170–182 [175] males, 178–185 [178] females in C. culminatus ); mid-dorsal scale rows 27–29 (mode=27) (vs. 27–33 [29] in C. culminatus ); width of paravertebral stripe of three scales, commonly with light center (vs. usually one in C. culminatus ); intercanthal scales absent (vs. 60% present in C. culminatus ); first infralabial scales not divided (vs. 56% divided in C. culminatus ); postrostral scale absent (vs. 44% present in C. culminatus ); prenasal-supralabial scales contact in 100% (vs. 80% present in C. culminatus ); interpreocular scale absent (vs. 20% present in C. culminatus ); usually two anterior intersupraocular scales (vs. usually three in C. culminatus ); presupraloreal absent (vs. often absent in C. culminatus ); postloreal absent (vs. often absent in C. culminatus ); postsupraloreal scale usually absent (vs. usually two in C. culminatus ); superciliar scale absent (vs. 20.8% present in C. culminatus ); lacunal-supralabial scales contact in 68% (vs. 16.6% in C. culminatus ); postocular stripe 3.0 – 3.5 scales width and light center (vs. three scales and faded coloration in C. culminatus ); dorsal body blotches in males usually 24 (23–27) (vs. usually 26 [22–30] in C. culminatus ); 23 (22–26) in females (vs. usually 27 [26–31] in C. culminatus ); contact between paravertebral stripes and supraoculars in 97% (vs. 24% in C. culminatus ); prefrontal bar interrupted in 100% (vs. 96% in C. culminatus ). Crotalus mictlantecuhtli is distinguished from C. simus by the absence of intercanthal scales (vs. presence of 10%), absence of presupraloreal scale (vs. rarely present), absence of postloreal scale (vs. rarely present), postsupraloreal scale rarely present (vs. usally present), superciliar scale absent (vs. rarely present), contac between lacunal and supralabial scales of 68% (vs. not contact), postocular stripe of 3.0–3.5 scales with light center (vs. three scales and faded), tertiary blotches not conspicuous (vs. conspicuous), paravertebral stripes often with light center (vs. usually without light center), contact of paravertebral stripes with supraoculars of 97% (vs. contact of 80%), prefrontal bar interrupted in 100% (vs. interrupted in 90%).

Description of the holotype. SVL 1283 mm, TL 132 mm, head length 59 mm, head width 43 mm; middorsal scale rows 29; midtail scale rows 11; rattle fringe scales 10; ventrals 170; subcaudals 28; supralabials 15; infralabials 16; rostral slightly higher than wide; internasals two, equally wider than long; canthal one on either side; intercanthals absent, with four scales in the internasal-prefrontal area; anterior intersupraoculars two; posterior intersupraoculars three; suture between intersupraoculars and canthals not evident; supraoculars the largest scales of the head scales; pre- and postnasals approximaltely equal in size; nostril mostly contained in postnasal; prenasals contact first supralabials; prefoveals five; lacunals contact the third supralabials; infraloreal and supraloreal present on both sides; postsupraloreal only on left side; upper preocular larger; lower preocular contacts loreal; interpreocular absent; five scales below center of the eye, between orbit and edge of the lip; mental triangular; first infralabials undivided; genials long, intergenials and submentals absent.

Crotalus mictlantecuhtli is not brightly patterned, usually having less contrast between the dark brown blotches and brown interspaces. Because is a preserved specimen, the coloration may have been faded. Head yellow cream above, dark brown prefrontal bar interrupted encompassing the canthals and anterior edges of intersupraoculars and supraoculars; dark brown paravertebral stripes reach the posterior edge of supraoculars with three to five scales width in the nape and light center; diagonal dark brown postocular bars 3.0–3.5 scales wide, not conspicuous as the paravertebrals, with light center; sides of head cream, with a brown spot beneath and posterior of loreal pit; underside of the head immaculate cream. Pattern of body consists of a pair dark brown paravertebral stripes 22 scales length, three scales wide, with light central scale, separated by light stripe three scales wide; first row of scales below each paravertebral buff, somewhat lighter than the lateral scales; 25 dark brown dorsal diamonds, sharper posteriorly, somewhat truncated anteriorly, each one bordered by a white scale, with light brown center, a secondary blotch associated in each side, below the lateral angle of the primary, of four to five scales and same color, tertiary blotches between secondary blotches not conspicuous; lateral areas between diamonds punctuated with light brown; toward the tail, the pattern becomes undifferentiated from ground color; tail brown above, buff below, without crossbands evident.

Color in life. Color in life varies with adult specimens presenting low contrast between blotches and interspaces, although some are more contrasting ( Fig. 6 ).

Variation. Largest male 1283 mm SVL, 132 mm TL (SDNHM 22416), and female 1360 mm SVL, 140 mm TL (UMA Palancoatl 50); ventrals 168–176 (mode=170; n= 17) in males, 169–178 (mode=174; n= 18) in females; subcaudals 27–32 (mode=28; n= 17) in males, 20–26 (mode=23; n= 18) in females; midbody scale rows 27 (n =27) or 29 (n =8); width of paravertebral stripe two (n= 1) or three (n =33) scales; length of the paravertebral stripe 18–35 (mode=26; n = 34); supraloreal scales 0 (n =8) or 1 (n =26); infraloreal scales 0 (n =2) or 1 (n =32); postsupraloreal scales 0 (n =20) or 1 (n =14); contact between lacunal and supralabial scales (n =23) or no contact (n =11); dorsal body blotches 23–27 (mode=24; n =17) in males, 22–26 (mode=23; n =18) in females; contact between paravertebral stripes and posterior edge of supraoculars (n =34) or no contact (n =1). We refer to Table 3 for variation in additional quantitative and qualitative features.

Etymology. The specific epithet “ mictlantecuhtli ”, derives from the Nahuatl word “ Mictlantecuhtli ” and means “Lord of Mictlán” or “Lord of the place of the dead”. In Mexican mythology (Aztec), Zapotec and Mixtec, Mictlantecuhtli is the god of the underworld and the dead. The species name is used as an invariable noun in apposition to the generic name. We suggested the vernacular name: Veracruz Neotropical rattlesnake.

Habitat and distribution. Crotalus mictlantecuhtli inhabits mostly open dry areas with rocky outcrops in tropical deciduous forest and seasonal rain forest along the Atlantic versant of Mexico from central-south Veracruz, from 0–1200 m asl. This species is known from the state of Veracruz, and may range to western Tabasco, and northeastern Oaxaca in the Atlantic slope on the border with Veracruz ( Fig. 4 ).

Figures

FIGURE 1. (A) Maximum-likelihood phylogram of the four genes (cyt b, ND4, ND2, c-mos, 2596 bp) analysis (-ln L=- 17,270.83). Tip labels are as follows: 3-letter subspecies code for the Crotalus durissus species complex, following Campbell & Lamar (2004), locality and haplotypes in parentheses, see Appendix 1. Numbers along branches indicate bootstrap support-ML and Bayesian posterior probability. For clarity, support is only shown for important nodes. (B) Maximum-likelihood phylogram of the four genes (cyt b, ND4, ND2, c-mos, 2596 bp) analysis (-ln L=-17,270.83). Tip labels are as follows: 3-letter subspecies code for the Crotalus molossus species complex and outgroups, following Campbell & Lamar (2004) and Anderson & Greenbaum (2012), locality and haplotypes in parentheses, see Appendix 1. Numbers along branches indicate bootstrap support-ML and Bayesian posterior probability. For clarity, support is only shown for important nodes.

FIGURE 4. Geographic distribution of species in the Crotalus durissus species complex distributed across Mexico and Central America. Circled dots indicate type localities. The circles indicate specimens where sequence and morphology were obtained; squares only morphology; triangles only sequences. Names of species reflect our proposed taxonomy.

FIGURE 5. Dorsal and lateral view of the head of the holotype of Crotalus mictlantecuhtli (SDNHM 22416).

FIGURE 6. Crotalus mictlantecuhtli in life, (A) juvenile specimen from El Zapote, Alvarado, Veracruz; (B) neonate specimen from Puerto de Veracruz, Veracruz; (C) adult specimen from Rinconada, Emiliano Zapata, Veracruz; (D) adult specimen from La Tinaja, Cotaxtla, Veracruz; (E) adult specimen from El Colibrí, La Antigua, Veracruz; (F) adult specimen from Rinconada, Emiliano Zapata, Veracruz. Photos by M.A. de la Torre Loranca (A), E. Centenero Alcalá (B, C, F), J.M. González Villa (D), and I. Ajactle Tequiliquihua (E).