Scincella gemmingeri

Barragán-Vázquez, Rosario, Ríos-Rodas, Liliana, Fucsko, Lydia Allison, Porras, Louis W., Mata-Silva, Vicente, Rocha, Arturo, DeSantis, Dominic L., García-Padilla, Elí, Johnson, Jerry D. & Wilson, Larry David, 2022, The herpetofauna of Tabasco, Mexico: composition, distribution, and conservation status, Amphibian & Reptile Conservation (e 315) 16 (2), pp. 1-61 : 18-20

Scincella gemmingeri *

Coniophanes schmidti 4

Leptodeira frenata 4

Agkistrodon russeolus 4

Crotalus tzabcan 4

Two of these eight species (25.0%) are country endemics and the remaining six are non-endemics. Of the six non-endemic species, one is an MXSA species and the other five are MXCA species.

In summary, of the 69 single-region species distributed in Tabasco, 51 (73.9%) are non-endemics, 16 (23.2%) are country endemics, and two (2.9%) are non-natives. Of the three physiographic regions in Tabasco, the SNC is of greatest conservation importance, given that it supports the largest overall number of species (145), as well as the largest numbers of single-region species (50) and country-endemics (13).

We constructed a Coefficient of Biogeographic Resemblance (CBR) matrix for establishing the herpetofaunal similarity relationships among the three physiographic regions in Tabasco ( Table 6). The SNC supports the highest level of species richness at 145 species, followed by 93 in the SBP, and 88 in the GCP. The mean species richness for the three regions is 108.7. The numbers of shared species among all regional pairs range from 61 between the GCP and the SBP to 79 between the SNC and the SBP. The average value of shared species among all three regions is 70.3.

The CBR data in Table 6 demonstrate values ranging from 0.61 to 0.67 (see below), with a mean value of 0.65. This range of CBR values is limited and the values are relatively high, indicating that many of these species are widespread.

We determined the numbers of species inhabiting one, two, and three of the recognized physiographic regions ( Table 7). In each of the two smaller herpetofaunas for the Gulf Coastal Plain and the Sierras Bajas del Petén subregion the numbers of species found in one, two, and three regions increase from the lowest to the highest value. However, in the area with the largest herpetofauna (145 species), the Sierra de Norte de Chiapas , the number of single-region species (50) is higher than the number of the double-region species (40), and is closer to the number of species occupying all three regions (55). Of the 170 total herpetofaunal species in Tabasco, 101 (59.4%) are found in two or three physiographic regions, leaving 69 (40.6%) with a distribution in only a single region (see above). Thus, 50 of these 69 single-region species are restricted to the Sierra Norte de Chiapas.

The highest CBR value (0.67) is that between the GCP and the SBP, and the lowest value (0.61) is between the GCP and the SNC. We expected a relatively high level of resemblance among these three areas, since the two higher-elevation regions are adjacent to the lowerelevation region, and all three regions contain relatively low elevations (see above).

The overall CBR values among the three physiographic regions are as follows, arranged from the highest to lowest value (species numbers in parentheses):

GCP (88) – 0.61 – SNC (145)

SBP (93) – 0.66 – SNC (145)

GCP (88) – 0.67 – SBP (93)

No. 13. Bolitoglossa veracrucis Taylor, 1951 . The Veracruz Salamander previously was known only from the type locality (Veracruz, Mexico), at 100 to 1,000 m elevation (https://amphibiansoftheworld.amnh.org/). In 2008, however, a population of this species was recorded for the first time in the state of Tabasco, from Cuevas de Muku Chem, in the municipality of Tacotalpa ( Gerónimo-Torres et al. 2022). Wilson et al. (2013b) calculated its EVS as 17, placing it in the middle portion of the high vulnerability category. Its conservation status has been considered as Endangered (EN) by IUCN, and as a species of Special Protection (Pr) by SEMARNAT. Photo by Marco Antonio Torrez-Pérez.

No. 15. Corytophanes hernandesii (Wiegmann, 1831) . Hernandez’s Helmeted Basilisk occurs at low and moderate elevations on the Atlantic versant from southeastern San Luis Potosí, Mexico, to northwestern Honduras ( McCranie et al. 2004). This individual was encountered in the Ejido Villa Guadalupe of Huimanguillo, Tabasco. Wilson et al. (2013a) determined its EVS as 13, placing it at the upper limit of the medium vulnerability category. Its conservation status has not been determined by the IUCN, but this species was provided Special Protection (Pr) status by SEMARNAT. Photo by José del Carmen Gerónimo-Torres.

No. 14. Corytophanes cristatus (Merrem, 1820) . The Smooth Helmeted Iguana is found at low and intermediate elevations on the Gulf and Caribbean slopes from central Veracruz to Colombia ( Lee 1996). This lizard ranges from central Veracruz and the southern part of the Yucatan Peninsula in Mexico, southward on the Atlantic versant and lowlands of Central America through northern Guatemala and Belize to Costa Rica, where it occurs on both the Atlantic and Pacific slopes into northwestern Colombia ( Campbell 1998). This individual was found in the municipality of Tacotalpa, Tabasco, in secondary vegetation. Its EVS has been determined as 11, placing it in the middle portion of the medium vulnerability category, and its IUCN status has been assessed as Least Concern (LC). This species was allocated to the Special Protection (Pr) category by SEMARNAT. Photo by Marco Antonio Torrez-Pérez.

No. 16. Norops barkeri Schmidt, 1939 . Barker’s Anole is a semiaquatic anole endemic to southern Mexico. This species is known from states of Veracruz, Chiapas, Oaxaca, and Tabasco (Powell and Birt 2001). This individual was found in the Ejido Villa Guadalupe of Huimanguillo , Tabasco. This lizard’s EVS has been assessed as 15, placing it in the lower portion of the high vulnerability category ( Wilson et al. 2013a). Its IUCN status has been determined as Vulnerable (VU), and it is considered a species of Special Protection (Pr) by SEMARNAT. Photo by Jenny del C.-Estrada-Montiel.

Based on the data in Table 6, we created a UPGMA dendrogram ( Fig. 5 ) to demonstrate the herpetofaunal resemblance patterns among the three physiographic regions in Tabasco (see map, Fig. 1 ). The dendrogram indicates that the CBP and GCP cluster at the 0.67 level and the SNC clusters to the previous pair at the 0.64 level. This overall pattern indicates that all three regions are closely aligned together at an intermediate level of resemblance.

Distribution Status Categorizations

We utilized the same system as Alvarado-Díaz et al. (2013) to examine the distribution status of members of the Tabasco herpetofauna, and this system has been used in all the subsequent entries in the MCS (see above). The categories in this system are non-endemic, country endemic, state endemic (of which none occur in Tabasco), and non-native. These categorizations are listed in Table 8 and summarized in Table 9.

The numbers of species in each of the three applicable categories, in decreasing order of size, are as follows: non-endemics, 145 (85.3% of total of 170 species); country endemics, 20 (11.8%); and non-natives, five (2.9%). As with the states of Oaxaca ( Mata-Silva et al. 2015), Chiapas ( Johnson et al. 2015a), Tamaulipas ( Terán-Juárez et al. 2016), Nuevo León (Nevárez-de los Reyes et al. 2016), Coahuila ( Lazcano et al. 2019), and Veracruz ( Torres-Hernández et al. 2021), as well as the tri-state Yucatan Peninsula ( González-Sánchez et al. 2017), most of the herpetofaunal taxa in Tabasco fall within the non-endemic category. In the other six states evaluated in the Mexican Conservation Series, the largest number falls within the country endemic category: Michoacán ( Alvarado-Díaz et al. 2013); Nayarit ( Woolrich-Piña et al. 2016); Jalisco ( Cruz-Sáenz et al. 2017); Puebla ( Woolrich-Piña et al. 2017); Hidalgo (Ramírez-Bautista et al. 2020); and Querétaro ( Cruz-Elizalde et al. 2022).

Twenty country endemic species are present in Tabasco, and perhaps this relatively low number was expected because the state lies largely on the Gulf Coastal Plain and adjacent to relatively low-elevation areas, which generally are not known for significant herpetofaunal endemism. No state endemic species occur in Tabasco. In the 13 previous entries in the MCS (including the Oaxaca update; Mata-Silva et al. 2021), the number of state endemic species ranges from one in Nayarit and Nuevo León ( Woolrich-Piña et al. 2016; Nevárez-de los Reyes 2016) to 105 in Oaxaca ( Mata-Silva et al. 2021).

Five non-native species have been recorded from Tabasco, including Eleutherodactylus planirostris , Norops sagrei , Hemidactylus frenatus , H. turcicus , and Virgotyphlops braminus . Two of these five species ( H. frenatus and V. braminus ) are the most widespread of the non-native species recorded in the 13 entries in the MCS ( Cruz-Elizalde et al. 2022), and to date they have been reported in 13 states or tri-state regions.

Wilson et al. (2017) introduced a system for the distributional categorization of the Mesoamerican herpetofauna. The data for the categories applicable to this work are summarized in Table 10. Previously, we noted that 145 species are non-endemic to Tabasco, and we allocated them to six of the nine categories developed by Wilson et al. (2017), including MXUS, MXCA, MXSA, USCA, USSA, and OCEA. As expected, the greatest number and proportion of species fall into the MXCA category (95, or 65.5%), given the proximity of Tabasco to Central America and since a significant portion of its eastern border is shared with Guatemala. Interestingly, the next largest number and proportion of species are allocated to the MXSA category (34, or 23.4%). Oddly, only a single species (0.7%) is assigned to the MXUS category. By way of comparison, this category contains 29 species, or 17.2%, in the herpetofauna of the adjacent state to the west (i.e., Veracruz; Torres-Hernández et al. 2021). The remaining 15 species are in the USCA (eight, or 5.5%), USSA (four, or 2.7%), and OCEA (three, or 2.1%) categories.

Figures

Fig. 5. UPGMA-generated dendrogram illustrating the similarity relationships of species richness among the herpetofaunal components in the three physiographic regions of Tabasco (based on the data in Table 6; Sokal and Michener 1958). Similarity values were calculated using Duellman’s (1990) Coefficient of Biogeographic Resemblance (CBR).

Fig. 1. Physiographic regions in the state of Tabasco, Mexico, and location of the state in Mexico.