Distribution of Crotalus Scutulatus (Kennicott, 1861) in Tamaulipas, Mexico and Notes on Earliest Seasonal Parturition

Herpetology Notes, volume 13: 1087-1093 (2020) (published online on 28 December 2020)

Distribution of Crotalus scutulatus (Kennicott, 1861) in Tamaulipas, Mexico and notes on earliest seasonal parturition

William L. Farr1 and Sergio A. Terán-Juárez2,*

Abstract. In Tamaulipas, Mexico, Crotalus scutulatus is known from only two specimens collected from the same locality almost a century ago. Both were catalogued as Crotalus atrox at that time and one of the two remained so as recently as 2003, while the other has been transferred between three collections and re-identified in the intervening years. Our aim was to locate additional records (museum, literature, and field) and establish the distributional limits of C. scutulatus in Tamaulipas. Fieldwork yielded additional records, which are mapped, and the habitat is described. Among the field records are neonates that indicate the earliest reported parturition dates for the species. To the best of our knowledge this is the first review that specifically addresses the occurrence of C. scutulatus in Tamaulipas.

Keywords. distribution, habitat, vegetation zones, parturition

Introduction the Northern Mohave Rattlesnake, C. s. scutulatus (Kennicott, 1861) and the Huamantla Rattlesnake, The Mohave Rattlesnake, Crotalus scutulatus C. s. salvini Günther, 1895. Crotalus s. scutulatus (Kennicott, 1861), inhabits the deserts of the south- is distributed from the Mojave Desert in southern western United States and the interior central plateau of California, the southern tip of Nevada, extreme south- Mexico. Recent studies have examined cryptic genetic western Utah, south-eastward through much of Arizona, diversity and geographic variation in morphology, northern Sonora, extreme southern New Mexico, the providing evidence that various populations of the Big Bend region of Texas, and southward across the species have undergone several episodes of isolation and Mexican Plateau, including southwest Tamaulipas, secondary contact that produced four genetic lineages: into Guanajuato. Crotalus s. salvini has been reported Mohave-Sonoran Desert, Chihuahuan Desert, Central from the south-central Mexican states of Hidalgo, Mexican Plateau, and southern Mexican matorral (C. Querétaro, Estado de México, Puebla, Tlaxcala, and s. salvini lineage), with the Tamaulipas population extreme central-west Veracruz (Klauber 1972; Price, included in the Central Mexican Plateau lineage 1982; Campbell and Lamar, 2004; Dominguez-Laso (Schield et al., 2018; Strickland et al., 2018; Watson et et al., 2007; Valencia-Hernández et al., 2007; Canseco- al., 2019). Watson et al. (2019) concluded that although Márquez and Gutiérrez-Mayen, 2010; Fernández- past isolation had produced clinal variations across Badillo et al., 2016); however, recent studies indicate its distribution, with renewed gene flow C. scutulatus a distribution restricted to only the latter four states was a cohesive species without discrete subgroups. (Schield et al., 2018; Strickland et al., 2018; Watson et Historically, two subspecies, referred to as “poorly al., 2019). The species has also been of interest in venom defined” by Watson et al. (2019), are recognised, research, with studies showing that the venom varies significantly among populations that are not correlated to the four major genetic lineages (Borja et al., 2018; Strickland et al., 2018; Zancolli et al., 2019). Although the occurrence of C. scutulatus in the state of Tamaulipas, Mexico, has been reflected in 1 1019 Wainfleet Lane, Houston, Texas, 77096, USA. 2 Tecnológico Nacional de México, Instituto Tecnológico de the literature for over 80 years, literature identifying Ciudad Victoria, Blvd. Emilio Portes Gil 1301, 87010, specific localities or museum specimens has been Ciudad Victoria, Tamaulipas, Mexico. lacking. We located only two prior museum vouchers * Corresponding author. E-mail: [email protected] MCZ R-19554 and SDNHM 6573. Both were collected 1088 William L. Farr & Sergio A. Terán-Juárez in June of 1924 from “Miquihuana, 80 mi SW Victoria” UANL, UCM, UF, UMMZ, USNM, UTA, and UTEP by professional collector Wilmot W. Brown, Jr., and (examined); FWM, JFBM, MCZ, MSUM, NMSU, deposited at the Museum of Comparative Zoology SMBU, UAZ (not examined). Standard symbolic codes (MCZ), where they were catalogued as Crotalus follow Sabaj (2019) with the exceptions of University atrox Baird and Girard 1853 (MCZ R-19554-19555). of Arlington Digital Collection (UTADC) and William Klauber (1930: 46) noted that the MCZ had C. atrox L. Farr personal field numbers (WLF). Additionally, we specimens from Miquihuana, Tamaulipas but explicitly searched the online database VertNet.org for additional stated that he had not examined them at that time and records from Tamaulipas and adjacent areas of the did not include them in his review due to the possibility neighbouring states of Nuevo León and San Luis Potosí. of confusion with C. scutulatus or C. basiliscus (Cope, Literature was reviewed for previous distributional 1864). One of the specimens (MCZ R-19555) was records and dates of birth. A total of 86 field days of transferred and catalogued in the private collection of herpetological surveys were conducted by the authors Laurence M. Klauber as C. scutulatus (LMK 6573) and in the municipalities of Bustamante, Miquihuana, later transferred again, and is now in the collection of the and Tula, where C. scutulatus might be anticipated to San Diego Natural History Museum (SDNHM 6573) occur; WLF conducted 71 field days of visual search (Bradford Hollingsworth, pers. comm.). However, as surveys and night driving performed in the months of recently as 2003, a request for data on MCZ Tamaulipas July-October, between 2003-2009; SATJ conducted herpetofauna included both MCZ R-19554 and 19555 15 field days of visual search surveys performed in the catalogued as Crotalus atrox. Klauber (1936) was the months of January, February, April, June-August and first to include Tamaulipas in the range of C. scutulatus, October, between 2014-2019. Locality coordinates and in his text and map, presumably based on one or both elevations of original field data were determined using of these specimens, however he did not identify any a GPS device using map datum WGS84. Distances museum specimens or specific localities. Over 80 years are expressed in straight air kilometres from the town of subsequent literature follow this pattern of noting square of municipality capitals. For the older museum and or mapping southwest Tamaulipas in the range and literature locality records that do not include of C. scutulatus, without identifying sources, data, coordinates and elevations, we have approximated voucher specimens, or localities (Gloyd, 1940; Smith these data using Google Earth (datum WGS84) and and Taylor, 1945; Wright and Wright, 1962; Klauber, these data are expressed in brackets [ ]. A model of 1972; Morafka, 1977; Price, 1982; Conant and Collins, the potential distribution of C. scutulatus available in 1991; Campbell and Lamar, 2004; Fernández-Badillo et a recent program for the conservation of the Mexican al., 2016; Heimes, 2016). Recently, Watson et al. (2019) rattlesnakes (SEMARNAT, 2018) was included in our mapped the distribution of C. scutulatus and included map and the records reported here are superimposed SDNHM 6573 as their only specimen from Tamaulipas. on the predicted optimal area for comparison. We It appears that the distribution of C. scutulatus in describe the habitat and vegetation in Tamaulipas where Tamaulipas is based solely on these two specimens C. scutulatus is known to occur and briefly discuss (MCZ R-19554 and SDNHM 6573 [formerly MCZ R- observations on natural history made during fieldwork. 19555 and LMK 6573]), both collected from the same locality over 95 years ago. Herein, we report on eight Results additional records produced in fieldwork conducted in Museum records yielded only the two previously Tamaulipas. known records MCZ R-19554 and SDNHM 6573 [both of which we estimated as having been collected at ca. Materials and Methods 23.5803°N, 99.7502°W, 1,895 m elev.]. Queries of The following institutions were queried for amphibian the online database VertNet.org yielded no additional and reptile voucher specimens from Tamaulipas which records from Tamaulipas, but 12 records for adjacent provided a total of over 16,100 records: AMNH, ANSP, areas of Nuevo León and one from San Luis Potosí (not BYU, CAS, CM, FMNH, INHS[UIMNH], KU, LACM, examined) were found (Nuevo Leon: CM 59879, CM LSUM, LSUS, MPM, MVZ, OMNH, OSUS, ROM, 59883, CM 59885, CM 59886, CM 59887, CM 59888, SDNHM, SRSU, TCWC, TNHC, TU [transferred in CM 59889, 59890, CM 59891, KU 187318, SDNHM 2011 to LSUM in Baton Rouge, Louisiana, USA (ca. 60478, TCWC 57191; San Luis Potosi: KU 67743). 80%) and SLU in Hammond, Louisiana, USA (ca. 20%)], Fieldwork in Tamaulipas produced eight records, one of Distribution of Crotalus scutulatus in Tamaulipas, Mexico 1089 which was deposited in the UANL collection, five were record is known from as close as 14 km. from UANL- deposited as photographic vouchers with UTADC, and 6633 and WLF-1704 in the neighboring municipality of two additional observations recorded in field notes with Jaumave [UANL 4842: 23.4415°N, 99.5290°W, 1,358 dates, localities, coordinates, temperatures, and other m.] however this record is separated by the Sierra Los data but not photographed. All available records, dates, Quemados and Sierra La Peña/Sierra El Pino ranges and localities from Tamaulipas are included in Table 1. and from an eastern basin oriented to the Jaumave Four records are from the municipality of Bustamante valley and eastern gulf drainage. Based on available and six from Miquihuana (Table 1). All available records records, C. atrox and C. scutulatus are not sympatric in from Tamaulipas and adjacent areas of the neighbouring Tamaulipas; however, it is possible that future fieldwork states are mapped (Fig. 1). and/or misidentified museum vouchers from collections we did not examine herein could reveal some overlap. Discussion Further fieldwork to sample for new records is needed in All records of C. scutulatus in Tamaulipas to date these areas in order to improve our knowledge about the are from arid, interior intermountain basins, valleys, geographical range and natural history of C. scutulatus and canyons of the municipalities of Miquihuana and in Tamaulipas (Fig. 1). Bustamante (Fig. 1). Farr (2015) included this area in the Among the C. scutulatus we found, seven were on Chihuahuan Desert, describing it under the “Chihuahuan roads at night, and one on a road near sunset. We never Desert foothills, canyons, and valleys assemblage” and encountered C. scutulatus in the field on foot, day or Terán-Juárez et al. (2016) described this area in “Gran night. Elevations in Tamaulipas range from 1,468 to Sierra Plegada” in reviews of physiographic regions 1,895 m in areas with predominantly late Cretaceous of Tamaulipas. The potential distributional model of limestone, where the canyon floors, valleys, and the lower C. scutulatus predicts their occurrence to the central- slopes are covered with recent alluvial deposits (Gómez- west of Miquihuana, Bustamante (except the mountains Hinostrosa and Hernández, 2000). Vegetation in these of the east edge) and in some areas of the northwest intermountain areas is an ecotone between Chihuahuan of Tula. We anticipated finding C. scutulatus in the Desert scrub flats dominated by microphyllous scrubs Chihuahuan desert scrub flats in the municipality of such as ocotillo (Fouquieria splendens), mesquite Tula to the south, however we only encountered C. atrox (Prosopis juliflora), creosote (Larrea tridentata), there. Conversely, C. atrox was not encountered, nor tasajillo (Cylindropuntia leptocaulis), lechuguilla (Agave do we have museum records, from the municipalities lechuguilla), huisache (Vachellia [Acacia] farnesiana), of Bustamante or Miquihuana. Eastward, a C. atrox acacia (Vachellia [Acacia] rigidula), and yucca (Yucca

Table 1. Localities, dates, coordinates (latitude and longitude), elevation (elev. m) and specimens of C. scutulatus from Tamaulipas, Mexico.Table 1. Localities, dates, coordinates (latitude and longitude), elevation (Elev. m) and specimens of C. scutulatus from Tamaulipas, Mexico.

Locality Date Latitude Longitude Elev. (m) Specimen Municipality of Miquihuana Miquihuana, 80 mi SW Victoria 18 June 1924 [23.5803 99.7502] [1895] MCZ R-19554 Miquihuana 27 June 1924 [23.5803 99.7502] [1895] SDNHM 6573 13.3 km SE of Miquihuana 27 Sept 2006 23.5069 99.6447 1726 UANL-6622 6.4 km SE of Miquihuana 3 July 2004 23.5558 99.6941 1781 UTADC 9534 13.5 km SE of Miquihuana 15 Aug 2004 23.5050 99.6436 1704 WLF-477 4.7 km E of Miquihuana 18 Sept 2007 23.5569 99.7116 1713 UTADC 9536 Municipality of Bustamante 10.3 km NE of Bustamante 8 Aug 2003 23.5000 99.6833 1663 UTADC 9533 6 km SSE of Bustamante 8 July 2004 23.3816 99.7524 1528 UTADC 9535 3.7 km SE of Bustamante 12 July 2004 23.4038 99.7463 1522 WLF-364 7.4 km S of Bustamante 10 Oct 2007 23.3716 99.7344 1468 UTADC 9537

Table 2. Births and field observations of neonates of C. scutulatus.

Observation Day and Month State Reference Neonate in field 8 July Tamaulipas This report Neonate in field 12 July Tamaulipas This report Birth * 18 July Chihuahua Van Devender and Lowe, 1977 Birth * 18 July Chihuahua Goldberg and Rosen, 2000 Neonates in field 11 August Arizona McCoy, 1961 Young of the year 14 August Arizona Gloyd, 1937 Young of the year 15 August Tamaulipas This report Birth 22 August N/A Klauber, 1972 Birth in field 24 August (before) California Greene et al., 2002 Birth * 26 August Arizona Goldberg and Rosen, 2000 Birth * 31 August San Luis Potosí Mellink, 1990 Newborn in field August-September Arizona Gates, 1957 Neonates in field August-October California Cardwell, 2008 Birth in field ca. 1-5 September California Greene et al., 2002 Birth 18 September N/A Klauber, 1972 Birth 20 September N/A Klauber, 1972 Birth * 24 September Chihuahua Goldberg and Rosen, 2000 Young of the year 10 October Tamaulipas This report * = Captive births by recently wild caught females; N/A = data not available.

1090 William L. Farr & Sergio A. Terán-Juárez

Figure 1. Geographic location of the study area (grey frame) in north-eastern Mexico, with a detailed map indicating the records of Crotalus scutulatus in south-western Tamaulipas and adjacent areas in Nuevo León and San Luis Potosí.

filifera); and higher altitude slopes with saxicolous of neonates date from shortly before 24 August and vegetation including Miquihuana sotol (Dasylirion ca.1-5 September (Greene et al., 2002), and August miquihuanense), narrow-leaf agave (Agave striata), to October (Cardwell, 2008). Klauber (1972) reported candelilla (Euphorbia antisyphilitica), Leatherstem C. s. scutulatus births “from various sources” on (Jatropha dioica), Barrel Cactus (Ferocactus pilosus), 22 August, 18 September, and 20 September. The and carneros yucca (Yucca carnerosana) (Gómez- majority of reports with specific dates of parturition Hinostrosa and Hernández, 2000; Treviño and Valiente, involve recently wild caught individuals from northern 2005). Elevations of this habitat range from ca. 1,500- locations in Arizona and Chihuahua that gave birth in 2,000 m (Treviño and Valiente, 2005). captivity (Van Devender and Lowe, 1977; Mellink, Klauber (1972) reviewed the months of birth from a 1990; Goldberg and Rosen, 2000) including the earliest total of 119 broods among all species of Crotalus: 41 dates of parturition known to us on 18 July (Table 2). (34.5%) in August; 41 (34.5%) September; 12 (10%) Among the snakes we observed in Tamaulipas were October; 9 (7.5%) July; 6 (5%) June; and 10 (8.5%) that two neonates found on 8 (UTADC 9535; Fig. 2) and were “clearly off-season”. Lowe et al. (1986) reported 12 July 2004 (WLF-364). Two larger juveniles, but that parturition by C. scutulatus occurred July to August undoubtedly identified as young of the year, were found and Ernst and Ernst (2012) reported July to September on 15 August 2004 (WLF-477) and 10 October 2007 with a peak in mid to late August. In Arizona, newborn (UTADC 9537). The two records from July predate have been reported in August (Gloyd, 1937; McCoy, previous reports of birth by a minimum of ten and six 1961) and late August and September (Gates, 1957). days, respectively. All four of these individuals had a In San Bernardino County, California, USA reports button with no additional rattle segments. “One of the

Table 1. Localities, dates, coordinates (latitude and longitude), elevation (Elev. m) and specimens of C. scutulatus from Tamaulipas, Mexico.

Locality Date Latitude Longitude Elev. (m) Specimen Municipality of Miquihuana Miquihuana, 80 mi SW Victoria 18 June 1924 [23.5803 99.7502] [1895] MCZ R-19554 Miquihuana 27 June 1924 [23.5803 99.7502] [1895] SDNHM 6573 13.3 km SE of Miquihuana 27 Sept 2006 23.5069 99.6447 1726 UANL-6622 6.4 km SE of Miquihuana 3 July 2004 23.5558 99.6941 1781 UTADC 9534 13.5 km SE of Miquihuana 15 Aug 2004 23.5050 99.6436 1704 WLF-477 4.7 km E of Miquihuana 18 Sept 2007 23.5569 99.7116 1713 UTADC 9536 Municipality of Bustamante 10.3 km NE of Bustamante 8 Aug 2003 23.5000 99.6833 1663 UTADC 9533 6 km SSE of Bustamante 8 July 2004 23.3816 99.7524 1528 UTADC 9535 3.7 km SE of Bustamante 12 July 2004 23.4038 99.7463 1522 WLF-364 Distribution of7.4 Crotalus km S of Bustamante scutulatus in Tamaulipas,10 Oct 2007Mexico 23.3716 99.7344 1468 UTADC 95371091

Table 2. Births and field observations of neonates of C. scutulatus. Table 2. Births and field observations of neonates of C. scutulatus.

best tests for the age of young rattlers is the presence the two neonates we observed in July were born ca. or absences of the pre-button“: rattlesnakes shed July 2 and 6 or earlier. Although data are limited, these their skins about 7-10 days after birth, if a pre-button observations suggest populations at southern latitudes is evident, it is likely less than 10 days old (Klauber, may give birth earlier than those further north, which 1972). Conversely, we infer if a pre-button is absent the is consistent with Klauber’s (1972) statement on USA snake is ca. one week old or older, which would indicate populations, that rattlesnakes from the warmest areas of the desert are born earlier than those from coastal areas and higher elevations.

Acknowledgements. We thank Bradford Hollingsworth and Laura Williams SDNHM: San Diego Natural History Museum; David Lazcano, UANL Universidad Autónoma de Nuevo León; Jose Rosado, MCZ Museum of Comparative Zoology, Harvard University for providing data and the opportunity to examine and report on material from their collections. Jonathan A. Campbell and Gregory G. Pandelis UTA for verifying and cataloguing our photographic vouchers. Fieldwork was conducted under SEMARNAT permits 7150/97 and FAUT-0045 issued to Pablo Antonio Lavin Murcio; and 1624/05, 0800/06, 1085/07, 1255/08, 2263/09 issued to David Lazcano Villarreal in collaboration with Pablo Antonio Lavin Murcio and William Lavelle Farr.

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Figure 2. A neonate C. scutulatus photographed on 8 July 2004 Borja, M., Neri-Castro, E., Castañeda-Gaytán, G., Strickland, J.L., at 6 km SSE of Bustamante, Tamaulipas, Mexico (UTADC Parkinson, C.L., Castañeda-Gaytán, J., et al. (2018): Biological 9535). Photo by William W. Farr. and proteolytic variation in the venom of Crotalus scutulatus 1092 William L. Farr & Sergio A. Terán-Juárez

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Accepted by Andrew Durso