Short Communication
Print
Short Communication
A partial molecular phylogeny of Rhadinaea and related genera (Squamata, Dipsadidae) with comments on the generic assignment of Rhadinaea eduardoi
expand article infoRicardo Palacios-Aguilar, Uri Omar García-Vázquez
‡ Universidad Nacional Autónoma de México (UNAM), Mexico, Mexico
Open Access

Abstract

The genus Rhadinaea is a diverse clade of New World dipsadid snakes, with 22 species arranged in six recognized species groups. The most recently described species, Rhadinaea eduardoi, was described based on a unique specimen collected in the Santa Catarina Juquila municipality in the Sierra Madre del Sur of southern Oaxaca, Mexico. Here, based on a reexamination of the holotype and the results of a phylogenetic analysis of the holotype of Rhadinaea eduardoi and representatives of several genera closely related to Rhadinaea, we reassessed the generic assignment of Rhadinaea eduardoi. In our phylogenetic hypothesis, R. eduardoi was nested within a strongly supported clade of Coniophanes fissidens samples, thus making Rhadinaea paraphyletic with respect to Coniophanes. Additionally, our reexamination of the holotype of Rhadinaea eduardoi revealed that the alleged presence of a subpreocular scale is only true on the right side of the head, and that this scale appears to be a malformed preocular scale; also, a reduction in dorsal scale rows is present; and posterior enlarged maxillary teeth are grooved. Herein we consider that Rhadinaea eduardoi should be placed in the synonymy of Coniophanes fissidens. Consequently, we recognized only five species groups within the genus Rhadinaea.

Keywords

Coniophanes, generic assignment, synonymization, taxonomy

Introduction

Dipsadid snakes are the most speciose family of snakes in the Western Hemisphere, with new species descriptions and taxonomic changes frequently modifying the current composition (García-Vázquez et al. 2018; Mata-Silva et al. 2019). Snakes of the genus Rhadinaea Cope, 1863 (Squamata: Dipsadidae) are distributed throughout Mesoamerica, ranging from the Sierra Madre Occidental of southern Sinaloa and Sierra Madre Oriental of northern Nuevo León in Mexico to northwestern Ecuador in South America, with an isolated species, R. flavilata (Cope, 1871), in the southeastern USA (García-Vázquez et al. 2018). Rhadinaea was formerly considered one of the most diverse New World snake genera, but after several taxonomic changes (see Myers 2011), only 22 species arranged in six species groups are currently recognized. These groups are (number of species in each group in parentheses) the Rhadinaea calligaster (1), R. decorata (12), R. eduardoi (1), R. flavilata (2), R. taeniata (3) and R. vermiculaticeps (3) groups (Myers 1974; García-Vázquez et al. 2018; Mata-Silva et al. 2019). The most recently described species, Rhadinaea eduardoi Mata-Silva, Rocha, Ramírez-Bautista, Berriozabal-Islas and Wilson, 2019 is known only from one specimen collected in the municipality of Santa Catarina Juquila in the Sierra Madre del Sur of southern Oaxaca, Mexico. According to the authors, R. eduardoi is most closely related to R. laureata (Günther, 1868), and is the only representative of its own species group (Mata-Silva et al. 2019). Herein, we present a phylogenetic analysis of Rhadinaea and related genera involving species (such as R. eduardoi) that were not previously included in the snake phylogeny. Together with a morphological analysis, we use this phylogeny to reassess the taxonomic status of the newly described R. eduardoi.

Materials and methods

Molecular procedures

To investigate the phylogenetic position of Rhadinaea eduardoi, we sequenced a fragment of the mitochondrial gene coding for Cytochrome b (cyt b) from 13 individuals including the holotype of R. eduardoi (Centro de Investigaciones Biológicas, Universidad Autónoma del Estado de Hidalgo, CIB5457); six samples of the remaining three Mexican species groups of Rhadinaea, including Rhadinaea decorata (Günther, 1858) (3), R. taeniata (Peters, 1863) (2) and R. laureata (Günther, 1868) (1); three samples of Rhadinella Smith 1941, including one sample each of R. hempsteadae (Stuart & Bailey, 1941), R. lachrymans (Cope, 1870) and R. stadelmani Stuart & Bailey, 1941, previously Rhadinaea godmani group; and four samples of Coniophanes Hallowell, 1860 (Table 1). Additionally, we obtained sequences from GenBank of an additional sample of Coniophanes fissidens (Günther, 1858) and single samples of Amastridium Cope, 1860; Pliocercus Cope, 1860; Synophis Peracca, 1896; and Tantalophis Duellman, 1958. All of these genera are considered closely related to Rhadinaea by previous authors (Myers 1974, 2011; Pyron et al. 2013). Finally, we used Hypsiglena jani Dugès, 1865 to root the tree (Table 1). This region of cyt b has been successfully employed to elucidate phylogenetic relationships within Dipsadidae (Lawson et al. 2005; Daza et al. 2009; Pyron et al. 2013). We extracted genomic DNA from muscle or liver tissue using the standard phenol-chloroform method (Hillis et al. 1996), and utilized polymerase chain reaction (PCR) to amplify the aforementioned fragment with the primers L14919, H16064 (Burbrink et al. 2000), L15584 (de Queiroz et al. 2002), and H15716 (Slowinski and Lawson 2002). We sequenced DNA templates with an ABI 3730xl DNA analyzer (Applied Biosystems, Inc.), using primers L14919 and H16064 (Burbrink et al. 2000).

Table 1.

Collection and voucher data for colubrid genetic samples used in this study. Acronyms for herpetological collections follow Sabaj (2019). RICB, JCSG, OFV, and UOGV are field identifiers for uncatalogued specimens being deposited in the MZFC-HE and UTA.

No. Voucher number Taxa Locality GenBank accession number
1 CAS228960 Hypsiglena torquata USA: Texas: Culberson Co. EU728592
2 KU289798 Coniophanes fissidens (1) El Salvador: San Salvador EF078538
3 RICB521 Coniophanes fissidens (2) Mexico: Chiapas: Road to La Encrucijada MT308775
4 MZFC-HE34715 Coniophanes fissidens (3) Mexico: Guerrero: Arenal de Gómez MT308776
5 RICB260 Coniophanes fissidens (4) Mexico: Veracruz: Ocotepec, Los Reyes MT308777
6 MZFC-HE15533 Coniophanes imperialis Mexico: Oaxaca: Santa Maria Chimalapa, Cofradia MT308778
7 CIB5457 Rhadinaea eduardoi Mexico: Oaxaca: El Obispo, Santa Catarina Juquila MT308779
8 UTAR44718 Rhadinaea decorata (1) Guatemala: Huehuetenango: Barillas, Finca Chiblac Buena Vista MT308780
9 JCSG58 Rhadinaea decorata (2) México: Veracruz: Sierra de Otontepec MT308781
10 OFV1109 Rhadinaea decorata (3) Mexico: Oaxaca: San Felipe Jalapa de Díaz MT308782
11 UOGV2181 Rhadinaea taeniata (1) México: Estado de México: Valle de Bravo MT308787
12 MZFC-HE23859 Rhadinaea taeniata (2) Mexico: Oaxaca Santa Maria Yavesia MT308788
13 MZFC-HE21661 Rhadinaea laureata México: Morelos: Huitzilac MT308785
14 UTAR42473 Rhadinella stadelmani Guatemala: Huehuetenango: 3.2 km WSW Patacal MT308786
15 UTAR42470 Rhadinella hemsteadae Guatemala: Quiche: Uspantán, road El Chimel-San Pablo MT308783
16 UTAR42335 Rhadinella lachrymans Guatemala: San Marcos: San Rafael Pie de La Cuesta, Finca America El Vergel MT308784
17 EBUAP1853 Tantalophis discolor México: Oaxaca: Sierra de Monte Flor EF078589
18 UTAR46905 Amastridium sapperi Guatemala: Izabal GQ334479
19 QCAZ9175 Synophis zamora Ecuador: Zamora Chinchipe: Las Orquídeas KT345376

Phylogenetic relationships

We aligned the obtained sequences using the Muscle algorithm (Edgar 2004) included in the software MEGA 7 (Kumar et al. 2016). The best-fitting substitution models and partitioning schemes were selected jointly using the Bayesian Information Criterion in the software PARTITIONFINDER 1.1.1 (Lanfear et al. 2012). We performed a Bayesian phylogenetic analysis with the software MRBAYES 3.2 (Ronquist et al. 2012). We ran the analysis for 50,000,000 generations with the default settings and tree sampling every 1000 generations. Output parameters were visualized using TRACER 1.4 (Rambaut and Drummond 2007) to verify stationarity and convergence. After discarding the first 25% as burn-in, we summarized parameter values of the samples from the posterior distribution on the maximum clade credibility tree using TREEANNOTATOR 1.4.8 (Drummond and Rambaut 2007) with the posterior probability limit set to 0.1 and mean node heights summarized. We considered clades with posterior probabilities (Pp) ≥ 0.95 as significantly supported (Huelsenbeck and Rannala 2004).

Genetic distances

To obtain an estimate of genetic distances, we computed pairwise genetic mean distances between Coniophanes, Rhadinaea, and R. eduardoi. We calculated the corrected pairwise genetic distances using the K2P model with MEGA 7 (Kimura 1980; Kumar et al. 2016).

Morphological comparisons

We compared the holotype of Rhadinaea eduardoi (CIB5457) with a series of Coniophanes specimens deposited at the Museo de Zoología “Alfonso L. Herrera”, Facultad de Ciencias, Universidad Nacional Autónoma de México (MZFC-HE). Scale nomenclature and ventral scale counts follow Myers (1974). To score the dorsal scale rows, we made three separate counts: the first located one head-length posterior to the head, the second located at midbody, and the third located four ventral scales anterior to the anal plate. We counted ventral scales as suggested by Dowling (1951a). Dorsal scale reduction formula is based on Dowling (1951b). Other scutellation characters that we scored were the number of preoculars, postoculars, supralabials, infralabials and subcaudals. We examined the maxillary dentition of the holotype in situ.

Results

Phylogenetic relationships

The final alignment consisted of 1055 bp. The partitions and models that best fit the data were GTR+G for the first and second codon positions, and GTR+G+I for the third codon position. In the Maximum Credibility Tree (Fig. 1), the haplotypes of Rhadinella (R. hempsteadae, R. stadelmani, and R. lacrymans) formed the sister taxon to all the remaining haplotypes. Except for the haplotype of R. eduardoi, the haplotypes of Rhadinaea comprised a clade where R. decorata was strongly supported as sister taxon to R. taeniata and these two taxa formed the sister taxon to R. laureata, the supposedly closest relative of R. eduardoi (Mata-Silva et al. 2019), although this relationship was not significantly supported. The Rhadinaea clade was the sister taxon to a significantly supported clade comprised of all the haplotypes of Coniophanes. The haplotype of R. eduardoi was nested within a significantly supported clade composed of all the haplotypes of C. fissidens, with C. imperialis (Baird & Girard, 1859) as the sister taxon to this clade.

Figure 1. 

Phylogenetic relationships and phylogenetic position of holotype of Rhadinaea eduardoi based on partial sequences of the mitochondrial gene Cytochrome b (cyt b). Numbers indicate the Bayesian posterior probabilities for each node.

Genetic distances

Genetic distances between species of Rhadinaea and R. eduardoi ranged from 18.9–22.4%, whereas distances between species of Coniophanes and R. eduardoi were much smaller (10.1–11.7%).

Morphology

Rhadinaea eduardoi was originally assigned to Rhadinaea due to the presence of a small subpreocular scale, the absence of dorsal scale row reduction, supralabial counts, and dorsal color pattern (Mata-Silva et al. 2019). Our reexamination of the holotype (CIB 5457) verified most of the meristic data presented by Mata-Silva et al. (2019), such as ventral and subcaudal counts. However, two characters differed notably compared to our reexamination: 1) the subpreocular is actually present only on the right side of the head and, furthermore, it appears to be a malformed preocular scale, and 2) dorsal scale row reduction is present, the arrangement being 17-17-15 with counts reduced by fusion of dorsal scale rows 8 + 9, according to the formula:

178+9(75)8+9(75)15(120)

Of additional diagnostic importance, the maxillary teeth posterior to the diastema are enlarged and grooved. Among other features, the genus Rhadinaea is characterized by having a small subpreocular inserted between the corners of two supralabials at the antero-ventral edge of the orbit; the same number of dorsal scale rows throughout the body; and not grooved maxillary teeth posterior to the diastema (Myers 1974, 2011). The characters present in the holotype of R. eduardoi are thus inconsistent with the current diagnosis of the genus Rhadinaea. Together with the molecular results presented above, this leads us to conclude that the generic allocation of R. eduardoi was erroneous.

Discussion

The phylogenetic relationships obtained in this study are generally consistent with previous phylogenies that suggested a close relationship between Amastridium, Coniophanes, Rhadinaea, and Tantalophis (Daza et al. 2009; Pyron et al. 2013), and that supported the separation of Rhadinella from Rhadinaea (Myers 2011). Pyron et al. (2013) found a strong relationship between Rhadinaea and Coniophanes, and both with Tantalophis discolor (Günther, 1860) and Amastridium veliferum Cope, 1860. These relationships are similar to our result, but with the inclusion of Synophis zamora Torres-Carvajal, Echevarría, Venegas, Chávez & Camper, 2015 and Pliocercus elapoides Cope, 1860 in the same clade of Amastridium and Tantalophis. Furthermore, we resolved Rhadinella as the sister clade of Rhadinaea + Coniophanes. Synophis, Pliocercus and Rhadinella were not included in the phylogeny of Pyron et al. (2013). Additionally, Daza et al. (2009) found a supported clade formed by Amastridium sapperi (Werner, 1903), Rhadinaea fulvivitis and Coniophanes fissidens, however, Tantalophis discolor appear basal to these taxa, plus another dipsadids in an unsupported clade. None of the other genera considered in our study were included by Daza et al. (2009). Although the phylogenetic relationships of Rhadinaea with the remaining genera included here were recovered with low support (< 0.95), it is evident that the clade containing C. fissidens and R. eduardoi is not closely related to the genus (Fig. 1). This result, in addition to the genetic distinctiveness, leads us to consider that the generic allocation of R. eduardoi was erroneous. Our revision of morphological characters agrees with this assessment. Hence, we also propose the recognition of only five species groups within Rhadinaea.

Bailey (1939) defined the genus Coniophanes as consisting of medium sized snakes with enlarged, grooved posterior teeth; posterior dorsal scale reduction through fusion of paravertebral rows; and one or two preocular scales – all characters present on the holotype of Rhadinaea eduardoi. The color pattern (diffuse and poorly defined lateral and middorsal stripes on body) and key characters (i.e., posterior dorsal scale reduction by fusion of paravertebral rows; and enlarged, grooved teeth posterior to the diastema) of the holotype clearly allocate it as a representative of Coniophanes fissidens (Fig. 2). However, some scutellation characters of the holotype merit discussion. The holotype shows a dorsal scale arrangement in 17-17-15 longitudinal rows, which is very rare in C. fissidens (see Smith 1941; and Campbell 1989 for a discussion on the variation exhibited by this species). Of over 100 specimens of C. fissidens (Palacios-Aguilar et al. in prep) examined from throughout its range in Mexico, only one specimen (MZFC-HE17791) from Santa María Huatulco, Cuenca del Río Magdalena, Oaxaca exhibited a similar arrangement. The presence of 17 scale rows at midbody is rarely seen in Coniophanes, but common in most Rhadinaea (Bailey 1939; Myers 1974), likely being one of the factors that led Mata-Silva et al. (2019) to a wrong generic allocation of R. eduardoi. The presence of a subpreocular scale is also rare in the genus Coniophanes, being consistently present only in the Coniophanes piceivittis species group (Bailey 1939; Flores-Villela and Smith 2009). Coniophanes fissidens is the most broadly distributed species within the genus, with many subspecies having been described (Smith 1941), and some authors considering it as a species complex (e.g. McCranie 2011).

Figure 2. 

Adult male Coniophanes fissidens (MZFC-HE34194) from East of Río Santiago, Guerrero, Mexico. This specimen was obtained approximately 60 kilometers WNW of the type locality of C. f. dispersus. Compare this specimen with images 2, 3, and 4 from Mata-Silva et al. (2019).

Based on morphology and geographic distribution, Rhadinaea eduardoi is perhaps best considered a junior synonym of C. f. dispersus, a subspecies distributed on the Pacific versant of Mexico west of the Isthmus of Tehuantepec from Jalisco to Oaxaca (sensu Smith, 1941). However, our phylogenetic tree shows a close relationship between the holotype of R. eduardoi and a sample from Veracruz, Mexico (C. f. fissidens) which together are the sister clade of a nearly topotypic sample of C. f. dispersus (Fig. 1, Table 1). The inclusion of additional samples would help to elucidate this interesting issue. For now, we refrain from recognizing subspecies within C. fissidens, pending the acquisition of more samples spanning the species’ wide distribution and the inclusion of additional molecular markers in a more comprehensive study. Hence, we simply suggest the synonymization of R. eduardoi with Coniophanes fissidens Günther, 1858.

Following the monographic treatment of the genus Rhadinaea by Myers (1974), scientific understanding of the composition of the genus has been further modified. The former brevirostris and lateristriga groups were accommodated in the resurrected genera Taeniophallus Cope, 1895 and Urotheca Bibron, 1840, respectively (Myers and Cadle 1994). Subsequently, Savage and Crother (1989), and Myers (2011) resurrected Rhadinella to include the former Rhadinaea godmani group. To date, no large-scale molecular phylogeny has included more than two taxa of Rhadinaea, nor any representatives of the genera mentioned above (e.g., Figueroa et al. 2016; Zaher et al. 2019), so the validity of this taxonomy (based only on morphological evidence) remains to be tested in a more comprehensive way. Also, while many authors have agreed that a close relationship between Rhadinaea and Coniophanes is likely, only a study by Cadle (1984) based on immunological data presented rigorous evidence to support this hypothesis. The present work thus provides the first insights into the phylogenetic relationships of these Neotropical snake genera, supporting the reciprocal monophyly of Rhadinaea and Rhadinella, and a close relationship between the former genus and Coniophanes as sister groups. Only a few morphological characters (dorsal scale reductions, number of preoculars, and teeth grooving) have been considered useful for differentiating Rhadinaea and Coniophanes (Bailey 1939; Cadle 1989; Myers 1974). As such, additional work including more comprehensive sampling of groups, the use of more molecular markers, and detailed revision of morphology is needed to explore their monophyly and evolutionary history.

Acknowledgements

Support for laboratory work was provided by grants from Dirección General de Apoyo al Personal Académico, Universidad Nacional Autónoma de México (PAPIIT grant number IN-216619) and Consejo Nacional de Ciencia y Tecnología (CONACyT A1-S-37838), to UOGV, and PAPIIT IN-216218 to O. Flores Villela. We thank A. Ramírez Bautista, V. Mata-Silva and C. Berriozabal-Islas for allowing us to study the R. eduardoi holotype. To Eric N. Smith (UTA), and Adrian Nieto Montes de Oca and O Flores Villela (MZFC) for the donation of several tissue samples. Our gratitude to U. A. García-Sotelo, J. C. Sanchez-García and R. G. Martinez-Fuentes for their help with laboratory work, Adam Clause for reviewing our manuscript for proper use of English. Adrian Nieto, Brett Butler, Robert C. Jadin and an anonymous reviewer for commenting on preliminary versions of this manuscript. RPA thanks CONACyT for a scholarship facilitated by the Posgrado en Ciencias Biológicas, UNAM (CVU 857990).

References

  • Bailey JR (1939) A systematic revision of the snakes of the genus Coniophanes. Papers of the Michigan Academy of Sciences, Arts and Letters 24: 1–48.
  • Cadle JE (1984) Molecular systematics of Neotropical xenodontine snakes: II. Central American xenodontines. Herpetologica 40: 21–30. https://doi.org/10.2307/1445144
  • Cadle JE (1989) A new species of Coniophanes (Serpentes: Colubridae) from Northwestern Peru. Herpetologica 45: 441–424.
  • Campbell JA (1989) A new species of colubrid snake of the genus Coniophanes from the highlands of Chiapas, Mexico. Proceedings of the Biological Society of Washington 102: 1036–1044.
  • Daza JM, Smith EN, Páez VP, Parkinson CL (2009) Complex evolution in the Neotropics: the origin and diversification of the widespread genus Leptodeira (Serpentes: Colubridae). Molecular Phylogenetics and Evolution 53: 653–667. https://doi.org/10.1016/j.ympev.2009.07.022
  • de Queiroz A, Lawson R, Lemos-Espinal JA (2002) Phylogenetic relationships of North American garter snakes (Thamnophis) based on four mitochondrial genes: How much DNA is enough? Molecular Phylogenetics and Evolution 22: 315–329. https://doi.org/10.1006/mpev.2001.1074
  • Dowling HG (1951a) A proposed standard system of counting ventrals in snakes. British Journal of Herpetology 1: 97–99.
  • Figueroa A, McKelvy AD, Grismer LL, Bell CD, Lailvaux SP (2016) A species-level phylogeny of extant snakes with description of a new colubrid subfamily and genus. PLoS ONE 11(9): e0161070. https://doi.org/10.1371/journal.pone.0161070
  • Flores-Villela O, Smith EN (2009) A new species of Coniophanes (Squamata: Colubridae), from the coast of Michoacán, Mexico. Herpetologica 65: 404–412. https://doi.org/10.1655/07-079.1
  • García-Vázquez UO, Pavón-Vázquez CJ, Blancas-Hernández JC, Blancas-Calva E, Centenero-Alcalá E (2018) A new rare species of the Rhadinaea decorata group from the Sierra Madre del Sur of Guerrero, Mexico (Squamata, Colubridae). ZooKeys 780: 137–154. https://doi.org/10.3897/zookeys.780.25593
  • Hillis DM, Mable BK, Larson A, Davis SK, Zimmer EA (1996) Nucleic acids IV: Sequencing and cloning. In Hillis DM, Moritz C, Mable BK (Eds) Molecular Systematics. Sinauer Associates, USA, 321–381. https://doi.org/10.2307/1447682
  • Huelsenbeck JP, Rannala B (2004) Frequentist properties of Bayesian posterior probabilities of phylogenetic trees under simple and complex substitution models. Systematic Biology 53: 904–913. https://doi.org/10.1080/10635150490522629
  • Kimura M (1980) A simple method for estimating evolutionary rate of base substitutions through comparative studies of nucleotide sequences. Journal of Molecular Evolution 16: 111–120 https://doi.org/10.1007/BF01731581
  • Kumar S, Stecher G, Tamura K (2016) MEGA7: Molecular Evolutionary Genetics Analysis version 7.0 for bigger datasets. Molecular Biology and Evolution 33: 1870–1874. https://doi.org/10.1093/molbev/msw054
  • Lanfear R, Calcott B, Ho SYW, Guindon S (2012) PartitionFinder: combined selection of partitioning schemes and substitution models for phylogenetic analyses. Molecular Biology and Evolution 29: 1695–1701. https://doi.org/10.1093/molbev/mss020
  • Lawson R, Slowinski JB, Crother BI, Burbrink FT (2005) Phylogeny of the Colubroidea (Serpentes): new evidence from mitochondrial and nuclear genes. Molecular Phylogenetics and Evolution 37: 581–601. https://doi.org/10.1016/j.ympev.2005.07.016
  • Mata-Silva V, Rocha A, Ramírez-Bautista A, Berriozabal-Islas C, Wilson LD (2019) A new species of forest snake of the genus Rhadinaea from tropical montane rainforest in the Sierra Madre del Sur of Oaxaca, Mexico (Squamata, Dipsadidae). ZooKeys 813: 55–65. https://doi.org/10.3897/zookeys.813.29617
  • McCranie JR (2011) The snakes of Honduras: systematics, distribution, and conservation. Society for the Study of Amphibians and Reptiles, Ithaca, New York, 714 pp.
  • Myers CW (1974) The systematics of Rhadinaea (Colubridae), a genus of New World snakes. Bulletin of the American Museum of Natural History 153: 1–262.
  • Myers CW (2011) A new genus and new tribe for Enicognathus melanauchen Jan, 1863, a neglected South American snake (Colubridae: Xenodontinae), with taxonomic notes on some Dipsadinae. American Museum Novitates 3715: 1–33. https://doi.org/10.1206/3715.2
  • Myers CW, Cadle JE (1994) A new genus for South American snakes related to Rhadinaea obtusa Cope (Colubridae) and resurrection of Taeniophallus Cope for the "Rhadinaea" brevirostris group. American Museum Novitates 3102: 1–33.
  • Pyron RA, Burbrink FT, Wiens JJ (2013) A phylogeny and revised classification of Squamata, including 4161 species of lizards and snakes. BMC evolutionary biology 13: 1–93. https://doi.org/10.1186/1471-2148-13-93
  • Ronquist F, Teslenko M, van der Mark P, Ayres DL, Darling A, Heohna S, Larget B, Liu L, Huelsenbeck JP (2012) MrBayes 3.2: efficient Bayesian phylogenetic inference and model choice across a large model space. Systematic Biology 61: 539–542. https://doi.org/10.1093/sysbio/sys029
  • Sabaj MH (2019) Standard symbolic codes for institutional resource collections in herpetology and ichthyology: an online reference. Version 7.1 (21 March 2019). American Society of Ichthyologists and Herpetologists, Washington, DC. http://www.asih.org/ [accessed 8 September 2019]
  • Savage JM, Crother BI (1989) The status of Pliocercus and Urotheca (Serpentes: Colubridae), with a review of included species of coral snake mimics. Zoological Journal of the Linnean Society 95: 335–362. https://doi.org/10.1111/j.1096-3642.1989.tb02315.x
  • Zaher H, Murphy RW, Arredondo JC, Graboski R, Machado-Filo PR, Mahlow K, Montingelli GG, Quadros AB, Orlov NL, Wilkinson M, Zhang YP, Grazziotin FG (2019) Large-scale molecular phylogeny, morphology, divergence-time estimation, and the fossil record of advanced caenophidian snakes (Squamata: Serpentes). PLoS ONE 14(5): e0216148. https://doi.org/10.1371/journal.pone.0216148

Supplementary material

Supplementary material 1 

Table S1. Specimens examined

Ricardo Palacios-Aguilar, Uri Omar García-Vázquez

Data type: Specimens examined

Explanation note: All of the specimens are Coniophanes fissidens from Mexico. Acronyms for herpetological collections follow Sabaj (2016).

This dataset is made available under the Open Database License (http://opendatacommons.org/licenses/odbl/1.0/). The Open Database License (ODbL) is a license agreement intended to allow users to freely share, modify, and use this Dataset while maintaining this same freedom for others, provided that the original source and author(s) are credited.
Download file (23.44 kb)