Herpetology Notes, volume 7: 797-805 (2014) (published online on 31 December 2014) Morphological variation in a population of Tantilla calamarina Cope, 1866 (Squamata: Colubridae) from Guerrero, Mexico, and comments on fossoriality in the calamarina group and Geagras redimitus Aurelio Ramírez-Bautista 1, *, Larry David Wilson 2 and Christian Berriozabal-Islas 1 Abstract. We studied the variation in morphological features seen in a large sample of the colubrid snake Tantilla calamarina from a single locality in Guerrero, Mexico. We confirm the status of Tantilla martindelcampoi as a synonym of T. calamarina. We also discuss the fossorial adaptations of the seven members of the T. calamarina group and the monotypic genus Geagras. Keywords. morphology, natural history, Tantilla calamarina, Guerrero, Mexico Resumen. Estudiamos la variación de las características morfológicas en una muestra grande de la culebra Tantilla calamarina de una sola localidad de Guerrero, México. En este trabajo confirmamos el estatus de Tantilla martindelcampoi como una sinonimia de Tantilla calamarina. También discutimos la adaptación fosorial de siete miembros del grupo T. calamarina y el género monotípico Geagras. Palabras claves. Morfología, historia natural, Tantilla calamarina, Guerrero, Mexico. Introduction Tantilla calamarina is one of 30 species of the genus Tantilla occurring in Mexico (Wilson and Mata-Silva, in press). This species has been placed in the pheneticallyestablished calamarina group (Wilson and Meyer, 1981; Wilson, 1999). This group presently contains seven species, of which six are endemic to Mexico (Townsend et al., 2013). 1 Centro de Investigaciones Biológicas, Universidad Autónoma del Estado de Hidalgo, A. P. 1-69 Plaza Juárez, B. P. 42001, Pachuca, Hidalgo, México; e-mail: aurelior@uaeh.edu.mx; CBI e-mail: christianberriozabal@gmail.com 2 Centro Zamorano de Biodiversidad, Escuela Agrícola Panamericana Zamorano, Departamento de Francisco Morazán, Honduras; e-mail: bufodoc@aol.com * Corresponding author Most of the Mexican members of the calamarina group are known from only two or three specimens (Wilson and Mata-Silva, in press), except for T. calamarina and T. deppei. Of the Mexican members, T. calamarina is the most widespread and the best represented in collections (Wilson and Meyer, 1981; Wilson and Mata-Silva, in press; this paper). Tantilla calamarina is distributed at low, moderate, and intermediate elevations (near sea level to about 1,700 m) of the Pacific versant from northern Sinaloa to south-central Guerrero, thence northward to the state of México and the Distrito Federal, including the Islas Marías (Wilson and Meyer, 1981). The remaining Mexican members of the calamarina group are distributed in restricted regions in the states of Guerrero (T. coronadoi, T. sertula), Michoacán and Jalisco (T. cascadae), Morelos and Oaxaca (T. deppei), and Jalisco and Nayarit (T. ceboruca). Two of these species recently have been reported from Jalisco (T. cascadae and T. ceboruca; Cruz-Sáenz et al., submitted).
798 Aurelio Ramírez-Bautista et al. Figure 1. Distribution of Tantilla calamarina in western Mexico, with inset showing locality for the specimens discussed in this paper. Wilson and Meyer (1981) studied variation in a number of scutellational and color pattern features in material they examined from throughout the extent of the range, especially in determining the status of the names Tantilla martindelcampoi Taylor, 1937, and Geophis gertschi Boger and Porter, 1966; both of these names were relegated by Wilson and Meyer (1981) to the synonymy of T. calamarina. To arrive at these taxonomic conclusions, these authors noted geographic variation in some features of head and body scutellation, as well as in dorsal color pattern. Unlike the situation with most species of Tantilla, the taxonomic work of Wilson and Meyer (1981) was possible because they had a large enough sample to support the synonimizations. The members of their sample, however, were unevenly distributed along the lengthy range of T. calamarina. For example, their sample E consisted of only four individuals from southcentral and central Guerrero. Conversely, we were fortunate to access a large sample of specimens of T. calamarina from the vicinity of Acapulco, Guerrero, which we allocated to Wilson and Meyer s sample E. Materials and Methods This study is based on a collection of 135 specimens of the colubrid snake Tantilla calamarina Cope, 1866. Of these, 94 (CIB 4301 4394) are deposited in the herpetological collection of the Centro de Investigaciones Biológicas of the Universidad Autónoma del Estado de Hidalgo and 41 (IBH-1177, 1622, 1637, 1647 1648, 2227 2228, 2309, 2380, 2982, 3022, 3635, 01648, 02227-2, 02227-3, 02227 4, 03635-1 25) in the Instituto de Biología, Universidad Nacional Autónoma de México (UNAM). We made scale counts using the standard techniques, including the Dowling (1951) method for counting ventral scales. Results Collection site The collections were assembled on 29 April 1978 by Zeferino Uribe Peña, Oscar Sánchez-Herrero, William López-Foment, and Edmundo Pérez-Ramos at El
Morphological variation in a population of Tantilla calamarina from Mexico 799 Huayacán (17 23 15.3 N, 101 16 51.63 W), Guerrero, Mexico, which is located 6 km SE Puerto Marquéz in the Municipalidad de José Azueta. At the time of collection, the site was an orchard of coconut palms, lemon trees, and mango trees located about 500 m from the beach, at an elevation from 50 to 100 m. The site today is a sports field (Figure 1). Microhabitat preferences The snakes were found under rocks and logs in an area with abundant leaf litter, and all of the microhabitats contained moist leaf litter. Invariable scutellational characteristics Based on the data provided by Wilson and Meyer (1981) and our own data, Tantilla calamarina is characterized by the following scutellational features: dorsal scales smooth, in 15 rows throughout; cloacal scute divided; nasal scale divided below naris; postocular single; temporals 1+1; and first pair of infralabials separated by contact of mental and anterior chinshields. Sex The sample of 135 specimens is composed of 60 males (44.4%) and 75 females (55.6%). Measurements In the material Wilson and Meyer (1981) studied, the total-length ranged from 72 to 91 mm (the latter value probably is a lapsus for 191) in 16 males and 104 202 mm in 22 females. The total length of the 60 males in our sample ranges from 78 to 251 mm, and that of the 75 females from 80 to 182 mm. Wilson and Meyer (1981) indicated the range in tail length as 13 36 mm in males and 13 29 mm in females. The tail lengths in our sample range, respectively, from 14 to 31 mm and 11 to 27 mm. Wilson and Meyer (1981) demonstrated that the ranges for relative tail lengths (tail length/total length) in males and females are non-overlapping; the range for males as 0.158 0.211, and that for females as 0.110 0.155 (converted from percentages to decimals). The comparable values for our sample are as follows: males 0.149 0.232; and females 0.123 0.171. A considerable degree of overlap is evident in our larger sample. Supralabials Wilson and Meyer (1981) noted that six s are present on both sides of most of the specimens they examined from throughout the range of the species, but that 6-5 and 5-5 are present on two specimens from Guerrero. In our sample, counts other than 6-6 are present in only four individuals (3.0%); we recorded individual counts of 4-5, 5-5, 6-5, and 6-7. These respective counts result from fusion of s 4, 5, and 6 on the left and 5 and 6 on the right, fusion of s 5 and 6 on both sides, fusion of the first and second scales of the right side, and division of the first scale of the right side. Supralabials entering the orbit As typical for the entire genus, the third and fourth s enter the orbit. We found this condition in all the specimens except two. In one, the second, third, and fourth s enter the orbit on both sides of the head, and in the other the fourth and fifth s enter the orbit on the right side of the head (seven s are present on that side). Infralabials Infralabials in this species range from 5 to 6. In most specimens, however, six infralabials are present on both sides of the head (111, 82.2%). The number and frequency of occurrence of the other states are as follows: 5-6 (8, 5.9%); 6-5 (9, 6.7%); and 5-5 (7, 5.2%). infralabials in contact with the anterior chin shields Either three or four infralabials are in contact with the anterior chin shields, in the following four combinations (with absolute and percentage values indicated parenthetically): 4+4 (112, 83.0%); 3+3 (9, 6.7%); 4+3 (8, 5.9%); and 3+4 (6, 4.4%). Largest infralabial The largest infralabial also is the last infralabial in contact with the anterior chin shields, so the combinations, absolute values, and percentage values are the same as indicated in the section above. s Wilson and Meyer (1981) relegated Tantilla martindelcampoi Taylor, 1937 to the synonymy of T. calamarina (see Introduction), and noted (p. 5), Taylor (1937) implied that a given specimen either has (calamarina) or lacks a preocular scale (martindelcampoi). Wilson and Meyer (1981: 5),
800 however, indicated that a preocular was present on both sides of the head of all specimens from their populations A-C (Sinaloa and Nayarit, including the Islas Marías), whereas 25.9% of those from popultions D-F [Colima, Michoacán, Guerrero, Morelos, México, and Distrito Federal] lack a preocular on one or both sides. A preocular scale is absent on either side of the head of most of the specimens we studied (128, 94.8%). We found counts of 1-0 (3.0%) in only four specimens, and three with counts of 1+1 (2.2%). Wilson and Meyer (1981) only examined four specimens from population E (to which our sample belongs), of which three (75.0%) lack a preocular on either side and one (25.0%) in which a preocular is present on both sides. Our data confirm and extend the pattern discerned by Wilson and Meyer (1981), indicating that most of the specimens from the southernmost portion of the range in coastal Guerrero lack the preocular scale. The preocular does not contact the postnasal in any of the specimens in our sample. Temporals A single elongate anterior temporal is present in T. calamarina. The identity of the two scales following the anterior temporal is not immediately apparent, as one is positioned behind the anterior temporal and follows the margin of the parietal scale; Wilson and Meyer (1981) considered this scale a posterior temporal. The other scale is located below and situated essentially posterior to the posterior tip of the anterior temporal, and could be considered a lower posterior temporal or as a first dorsal body scale. These designations are debatable, but single anterior and posterior temporals are present in most species of Tantilla, and seven s also are present in most species (Wilson, 1982). The head of T. calamarina also appears foreshortened, in concert with the reduction of certain head scales compared to the condition in most species of the genus, which could explain the appearance of the scales immediately posterior to the anterior temporal. Another feature of the temporal scales is that the anterior one is in contact with the postocular, i.e., the fifth might or might not contact the parietal scale. Wilson and Meyer (1981) demonstrated that all conditions between a broad contact and a broad separation of the and parietal exist without a discernible geographic pattern in this species, and that the implication of Taylor (1937) that the fifth either is in contact with the parietal (calamarina) or is not (martindelcampoi) is incorrect. Wilson and Meyer (1981, Table 2) presented data on the condition on both sides of the head of 38 specimens (except on one side of one specimen) from all portions of the range, illustrating the following four conditions (with absolute and percentage values indicated parenthetically): fifth and parietal separated (36 sides, 48.0%); barely separated (16, 21.3%); barely in contact (6, 8.0%); and in contact (17; 22.7%). In population E, however, the two scales are separated on eight sides. In our sample, however, considerable variation is present in the fifth parietal contact. We recorded the data to illustrate the following three conditions (with absolute and percentage values indicated parenthetically): fifth and parietal separated on both sides (81 individuals, 60.0%), separated on one side only (left or right) and in contact on the other (four individuals, 3.0%), or in contact on both sides (50 individuals, 37.0%). These data support the conclusions of Wilson and Meyer (1981) concerning variation in this feature. Ventrals Aurelio Ramírez-Bautista et al. Wilson and Meyer (1981) provided range-wide ventral counts for 16 male and 22 female specimens, with the respective ranges and means: 113 133 (120.3) and 123 140 (129.4). The counts noted for three males and one female from population E are, respectively, 113 122 (116.3) and 123. Our respective data for 60 males and 75 females are 113 126 (116.8) and 110 128 (121.8). These data support the conclusions reached by Wilson and Meyer (1981: 5), indicating a clinal decrease in ventral number proceeding southward In addition, a surprising congruence exists in the ranges and means for the three male population E specimens reported by Wilson and Meyer (1981, Table 3) and those reported herein. These values are, respectively, 113 122 (116.3) and 113 126 (116.3). Although the lowest ventral counts for the species were made in material from population E, the nature of the apparent southward clinal decrease in ventral numbers in this taxon remains unclear. Subcaudals Wilson and Meyer (1981) reported range-wide subcaudal counts for 16 males and 21 females, and provided the following respective counts: 30 42 (36.6) and 25 33 (28.6). The counts for three males and one female from population E were, respectively, 37 39 (37.6) and 29. We collected data for 62 males and 73 females (no specimens with incomplete tails), and their respective ranges and means are: 30 39 (36.1) and 25 37 (28.2). These data support several conclusions. First, we show the subcaudal count of 39 for the holotype of
Morphological variation in a population of Tantilla calamarina from Mexico 801 Tantilla martindelcampoi that Taylor (1937) considered to be significantly higher than counts for calamarina (Wilson and Meyer, 1981: 6) to be at the upper end of the range for the 60 males in the sample. The upper limit for these males is only 3 scales below the one reported by Wilson and Meyer (1981) from throughout the species range. The range for the 75 females expands the known range by four scales, at the upper end. The mean value for males and females in the El Huayacán sample is only 0.5 and 0.6 scales below the rangewide mean, respectively (Wilson and Meyer, 1981). Finally, as typical for members of the genus Tantilla, males average more subcaudals than females; in T. calamarina, the mean number for males is 8.1 higher than for females. Ventrals plus subcaudals Wilson and Meyer (1981) provided no data for ventrals plus subcaudals. The separate data discussed above for these scales, however, indicate that, as typical for species of Tantilla, more subcaudals are present in male T. calamarina than in females. Thus, when we summed the values for these scales, we expected the mean numbers between the sexes to diminish. Our data demonstrates this to be the case. In males, the range of ventrals + subcaudals is 147 162, and the mean is 152.8, whereas in females the range of ventrals + subcaudals is 143 156, and the mean 150.0. These mean values are separated by only 2.8 scales, as compared to 5.1 scales for the ventrals and 8.1 scales for the subcaudals (see above). Color pattern variation We noted color pattern distinctions between Tantilla martindelcampoi and T. calamarina. Wilson and Meyer (1981: 6) noted that, Smith (1942) mentioned that Tantilla martindelcampoi can be distinguished from T. calamarina by the presence of the lateral stripe on the adjacent halves of rows 4 and 5, instead of rows 3 and 4 [in the latter]. This distinction was echoed by Hartweg (1944) and Smith and Taylor (1945). Peters (1954) pointed out that the specimen of T. calamarina from Queseria, Colima was stated by Taylor (1937) to have the lateral dark stripe on rows 4 and 5, as also was stated to be the case in the holotype of T. martindelcampoi, described in the same paper. We suspect that Taylor (1937) did not make the distinction between the two species in lateral stripe placement, because none existed. The distinction was made subsequently (Smith, 1942). We have seen no specimens assigned to either calamarina or martindelcampoi with a lateral dark stripe placed elsewhere than on rows 3 and 4, including the holotype of martindelcampoi and the Colima calamarina discussed in Taylor s 1937 paper. Wilson and Meyer (1981: 6), however, indicated that, there are geographic differences in pattern, some of which were alluded to by Zweifel (1960) and McDiarmid et al. (1976). These differences involve the width and definition of the middorsal dark stripe and, to a lesser extent, the definition of the lateral stripe. In all but one specimen (AMNH 19750) from populations A, B, and C, the middorsal stripe is confined to the middle of the middorsal rows In all members of populations D, E, and F, the middorsal dark stripe covers all of row 8 and in all but one specimen, the adjacent portions of rows 7 and 9 Wilson and Meyer (1981: 6) additionally noted that in all specimens in populations A, B, and C the lateral stripe is found on the upper edge of row 3 and lower edge of row 4 or one the middle of row 3 and the middle of row 4 In at least 20 of 30 specimens from populations D, E, and F the lateral stripe is broader and better-defined, being present on the upper half of row 3 and the lower half of row 4 In the remainder of the specimens the stripe is either too faded to determine its precise nature or is as narrow as it is in some of the more northern specimens. With respect to head coloration, Wilson and Meyer (1981: 6) pointed out that there is some variation in the head pattern but it does not appear to be geographic. In some specimens the postparietal pale spots are relatively large and prominent and in others they are smaller. The anterior extensions of the pale nape markings are welldefined and complete (at least to behind the eye) or they are broken and poorly-defined. In some specimens this anterior extension is absent. We describe the color pattern of the material we studied from Guerrero as follows: in preservative, the dorsal ground color is pale cream, with each dorsal scale exhibiting a faint dark line on its median portion; three dorsal dark stripes are present in all specimens; the lateral lines lie on the third and fourth scale rows, and the vertebral stripe covers the middorsal scale and the adjacent halves of the paravertebral rows; all ventrals scales are immaculate pale cream; in males, small faint pale brown spots are present on the lateral portions of the subcaudals, whereas in females these dark spots are more conspicuous. The head pattern of males and females consists of a dark marking (paler medially, darker peripherally) along most of the parietals, all of the frontal, the medial edge of the supraoculars, and the
802 posteromedial portion of the prefrontals. This marking is confluent with the dark middorsal stripe, and thus looks like a spatula, as described by Wilson and Meyer (1981). This dark central pattern is bounded laterally on the parietals by a pale extension of the postparietal pale markings; these, in turn, are confluent with the dorsolateral pale fields bounding the middorsal dark stripe that occupies the middorsal scale row and the adjacent portions of the paravertebral scale rows. This description, therefore, is consistent with the one provided by Wilson and Meyer (1981) for most specimens from their populations D, E, and F. Discussion and Conclusions Variation in the Guerrero sample of T. calamarina and confirmation of the status of T. martindelcampoi A sample of a Mesoamerican species of Tantilla as large as the one we have studied from Guerrero is extremely unusual. The data we amassed from these 135 individuals provided a much greater understanding of the range of variation in scutellation and coloration; in addition, our analysis confirms the conspecificity of T. calamarina and T. martindelcampoi, initially established by Wilson and Meyer (1981). Tantilla martindelcampoi was described from a single specimen allocated to Wilson and Meyer s (1981) population E, the same population of our large sample. Fossorial adaptations among members of the T. calamarina group and Geagras redimitus Tantilla calamarina has been assigned to a phenetic group of seven species distributed at low, moderate, and intermediate elevations (near sea level 2,438 m) of the Pacific versant of Mesoamerica from northern Sinaloa to northwestern Costa Rica, including Morelos, the Distrito Federal, the state of México, Puebla, and the Islas Marías in Mexico (Wilson and Meyer, 1981; Canseco- Márquez et al., 2007; Wilson and Johnson, 2010; Wilson and Mata-Silva, in press). A sizable distribution gap between members of the group endemic to Mexico exists (six of the seven species) and the southernmost group member (T. vermiformis); this gap extends from central Guerrero (the southernmost point of the range of T. calamarina) to central El Salvador (the northernmost point of the range of T. vermiformis). Prior to the work of Holm (2008), aside from analyses of scutellation and color pattern, little other information was available on the phylogenetic relationships among members of the Tantilla calamarina group, as well as Aurelio Ramírez-Bautista et al. for Geagras redimitus. Wilson and Meyer (1981: 22) opined that, T. calamarina appears to be the species of Tantilla most highly specialized for a fossorial existence and Geagras redimitus appears to be another step in a morphocline of increased fossorial adaptation. In addition to the departures made by T. calamarina, Geagras has a more attenuate head [with an acute and produced rostral scale], smaller eye and lower number of s. Since the review of the calamarina group by Wilson and Meyer (1981), the species T. vermiformis was added to this group by Wilson (1999), Wilson and Campbell (2000) described a sixth species in the group, T. sertula, and Canseco-Márquez et al. (2007) added a seventh, T. ceboruca. Holm (2008) undertook a phylogenetic study of the Sonorini, a tribe of burrowing snakes allocated to the family Colubridae. A number of important conclusions were reached in this study; however, this work is a doctoral dissertation that remains unpublished. Nonetheless, the conclusions Holm reached concerning the Tantilla calamarina group and the monotypic genus Geagras are worth discussing. On page 97 Holm stated that Wilson and Meyer (1981) defined the T. calamarina group by the presence of dark lines and a spatulate extension of the vertebral dark line onto the top of the head. They also noted the similarity and probable relationship to the highly fossorial species Geagras redimitus. Wilson and Meyer (1981) also noted that the degree of fossoriality increased from T. deppei to T. calamarina, culminating with Geagras. Holm (2008: 98) concluded that the phylogenetic hypothesis [in his dissertation] confirms the inclusion of Geagras within the T. calamarina group. Characters uniting Geagras with T. calamarina include absence of contact between the prefrontal and nasal bones, a single postocular, and traits associated with small size and fossoriality. Geagras deviates from the group by its complete absence of scale row reductions [immediately behind the head] and absence of the left oviduct. Geagras redimitus also resembles T. calamarina and other members of the calamarina group in having a head pattern consisting of a spatulate anterior extension of the middorsal dark stripe that is outlined on either side by a distinct pale border. Holm (2008: 98) also concluded that his results do not include T. vermiformis in the T. calamarina group as suggested by Wilson (1999) and Wilson and Campbell (2000). Similarities between these taxa may be due to convergent adaptations for fossoriality and the dark vertebral line is a shared primitive trait. Tantilla vermiformis has a temporal scale configuration resembling other higher Tantilla.
Morphological variation in a population of Tantilla calamarina from Mexico 803 Holm (2008: 123) constructed a phylogenetic tree based on morphological data using maximum parsimony, and included three major clades, i.e., the Tantilla, Ficimia, and Sonora clades. Within the Tantilla clade, the members of the calamarina group (T. calamarina, T. cascadae, T. coronadoi, and T. deppei) cluster with Geagras redimitus, and G. redimitus is the sister species to T. calamarina. These two taxa are sister to T. cascadae and the three to T. coronadoi. Finally, these four taxa are sister to T. deppei. These relationships are consistent with a hypothesis of increasing fossoriality in the direction from T. deppei to G. redimitus. Holm (2008), however, did not include Tantilla ceboruca and T. sertula in his analysis, even though the former was described in 2000 and the latter in 2007. Inclusion of these two species in an analysis of fossorial adaptation in this group of Tantilla reinforces the hypothesis of evolution in this group toward increasing fossoriality. Testing this hypothesis will be possible when sufficient material becomes available to allow for a molecular systematic analysis. Our hypothesis is constructed using solely data on scutellation, with the understanding that only T. calamarina and T. deppei are known from more than two or three specimens. In erecting this hypothesis, we are assuming that adaptations toward increasing fossoriality involve the reduction in number of and/or fusion between elements of the head scutellation, as well as the reduction in the numbers of ventral and subcaudal scales, as demonstrated in other studies of semi-fossorial and fossorial snakes (Downs, 1967; Wilson and Meyer, 1981; Holm, 2008). We placed these data in Table 1. We defined the character states for these scutellational features and their direction of change as follows: present to absent 1 Yes in contact with postnasal Yes to No 1 Yes 3 No fused with prefrontal and supraocular No to Yes 1 No postoculars 2 to 1 1 2 2 2 or 1 3 1 Fifth separated from parietal Yes to No 1 Yes 3 No Sixth fused with anterior temporal No to Yes 1 No Seventh and parietal in contact No to Yes 1 No 2 Yes s 7 to 6 to 5 1 7 2 6 or 7 3 6 4 Usually 6 5 5 Supralabials entering orbit 3+4 to 3 1 3+4 2 3 ventrals more to fewer 1 153 or more 2 152 or fewer subcaudals more to fewer 1 54 or more 2 53 or fewer For each character, we then determined the character states for each species, then summed them, and placed these values for an index of fossoriality in Table 2. In this table, progressively higher total values signify a greater degree of fossorial adaptation. The total values range from a low of 12 in T. sertula to a high of 24 in G. redimitus. When placed in numerical sequence according to the total index value, the arrangement of species, from least to more adapted to fossoriality, is as follows: T. sertula (index of fossoriality = 12); T. deppei (13); T. ceboruca (14); T. coronadoi (14); T. cascadae (15); T. vermiformis (16); T. calamarina (21); and G. redimitus (24). The species in the calamarina group included in the Holm (2008), i.e., T. deppei, T. coronadoi, T. cascadae, T. calamarina, and G. redimitus, are arranged in the same order in our analysis. Obviously, this index of fossoriality is not to be confused with a phylogeny, but once a molecular phylogeny can be built, it will be interesting, and perhaps informative, to compare that phylogeny with our index. Obviously, however, low indices are found in the more generalized calamarina group species, such as T. sertula and T. deppei (12 and 13, respectively), intermediate values are found in the
804 Aurelio Ramírez-Bautista et al. Table 1. Characteristics of Tantilla calamarina group species (including Geagras redimitus) relating to degree of fossoriality. Species name present in contact with postnasal fused with prefrontal and supraocular postoculars Fifth separated from parietal Sixth fused with anterior temporal Seventh and parietal in contact s Supralabials entering orbit ventrals (males/females) subcaudals (males/females) T. calamarina Yes or no Yes or no No 1 Yes or no No No Usually 6, but infrequently 4, 5, or 7 3+4 113 133 (117.5)/110 140 (123.5) 30 42 (36.2)/25 37 (28.3) T. cascadae Yes Yes No 2 Yes No No 6 3+4 139 146/144 30 37/48 T. coronadoi Yes Yes No 1 or 2 Yes No Yes 7 3+4 158/165 35+/40 T. ceboruca Yes Yes or no No 2 Yes No No 7 3+4 138 146 (142.0)/153 42 47 (44.5)/36 T. deppei Yes Yes No 2 Yes No No Usually 7, but sometimes 6 3+4 142 150 (145.7)/153 168 (159.9) 54 60 (56.9)/43 48 (45.8) T. sertula Yes Yes No 2 Yes No No 7 3+4 153 161 30 37 T. vermiformis Yes Yes or no Yes or no 2 Yes Yes or no No 7 3+4 115 123 (119.6)/120 129 (124.2) 23 28 (25.3)/19 24 (21.0) G. redimitus Yes No No 1 No No No 5 3 113 124 26 33 more adapted species, such as T. ceboruca, T. coronadoi, T. cascadae, and T. vermiformis (14 to 16), and high indices in the most adapted species, i.e., T. calamarina and G. redimitus (21 and 24, respectively). We understand that this is a rough analysis based solely on scutellational features and therefore cannot be construed to support either of Holm s (2008) contentions, i.e., that T. vermiformis is not a member of the calamarina group or that Geagras redimitus should be allocated to the genus Tantilla. Answering these two questions, as well as those relating to the phylogenetic relationships of the remainder of the species included in this discussion, will have to await the assembly and evaluation of sufficient molecular material to allow for a robust analysis. Acknowledgments. We are grateful to Vicente Mata-Silva and Louis W. Porras for reviewing this manuscript prior to its submission for publication. We also are thankful to Zeferino Uribe Peña, Edmundo Pérez Ramos, William López-Forment, and Oscar Sánchez Herrera for their help in the field, and to Victor Hugo Reynoso at the Colección Nacional de Anfibios y Reptiles (CNAR) del Instituto de Biología, Universidad National Autónoma de México for allowing us to examine specimens in this collection. References Bogert, C.M., Porter, A.P. 1966. A new species of Geophis (Serpentes: Colubridae) from the state of Colima, Mexico. American Museum Novitates 2260: 1 10. Canseco-Márquez L., Smith, E.N., Ponce-Campos, P., Flores- Villela, O., Campbell, J.A. 2007. A new species of Tantilla Table 2. Calculation of index of fossoriality in T. calamarina group and G. redimitus. Species name present in contact with postnasal fused with prefrontal and supraocular postoculars Fifth separated from parietal Sixth fused with anterior temporal Seventh and parietal in contact s Supralabials entering orbit ventrals (males/females) subcaudals (males/females) Totals T. calamarina 2 2 1 3 2 1 1 4 1 2 2 21 T. cascadae 1 1 1 1 1 1 1 3 1 2 2 15 T. ceboruca 1 2 1 1 1 1 1 1 1 2 2 14 T. coronadoi 1 1 1 2 1 1 2 1 1 1 2 14 T. deppei 1 1 1 1 1 1 1 2 1 2 1 13 T. sertula 1 1 1 1 1 1 1 1 1 1 2 12 T. vermiformis 1 2 2 1 1 2 1 1 1 2 2 16 G. redimitus 1 3 1 3 3 1 1 5 2 2 2 24
Morphological variation in a population of Tantilla calamarina from Mexico 805 (Squamata: Colubridae) of the calamarina group from Volcán Ceboruco, Nayarit, Mexico. Journal of Herpetology 41: 220 224. Cruz-Sáenz, D., Muñoz-Nulasco, F.J., Lazcano, D., Flores- Covarrubias, E. Submitted. Noteworthy records for Tantilla cascadae and T. ceboruca (Squamata: Colubridae) from Jalisco, Mexico. Check List Dowling, H.G. 1951. A proposed standard system of counting ventrals in snakes. British Journal of Herpetology 1: 97 99. Downs, F. L. 1967. Intrageneric relationships among colubrid snakes of the genus Geophis Wagler. Miscellaneous Publications, Museum of Zoology, University of Michigan 131: 1 193. Hartweg, N. 1944. Remarks on some Mexican snakes of the genus Tantilla. Occasional Papers of the Museum of Zoology, University of Michigan 486: 1 9. Holm, P.A. 2008. Phylogenetic biology of the burrowing snake tribe Sonorini (Colubridae). Ph.D. dissertation, University of Arizona, Tucson, Arizona, USA. 242 pp. McDiarmid, R.W., Copp, J.F., Breedlove, D.E.1976. Notes on the herpetofauna of western México: New records from Sinaloa and the Tres Marías Islands. Natural History Museum of Los Angeles County Contributions to Science 275: 1 17. Peters, J.A. 1954. The amphibians and reptiles of the coast and coastal sierra of Michoacán, Mexico. Occasional Papers of the Museum of Zoology, University of Michigan 554: 1 37. Smith, H.M. 1942. A résumé of Mexican snakes of the genus Tantilla. Zoologica 27: 33 42. Smith, H.M., Taylor, E.H. 1945. An annotated checklist and key to the snakes of Mexico. United States National Museum Bulletin 187: 1 239. Taylor, E.H. 1937. Notes and comments on certain American and Mexican snakes of the genus Tantilla, with descriptions of new species. Transactions of the Kansas Academy of Science 39: 335 348. Townsend, J.H., Wilson, L.D., Medina-Flores, M., Herrera-B, L.A. 2013. A new species of centipede snake in the Tantilla taeniata group (Squamata: Colubridae) from premontane rainforest in Refugio de Vida Silvestre Texíguat, Honduras. Journal of Herpetology 47: 191 200. Wilson, L.D. 1982. Tantilla. Catalogue of American Amphibians and Reptiles. 307.1 307.4. Wilson, L.D. 1999. Checklist and key to the species of the genus Tantilla (Serpentes: Colubridae), with some distributional commentary. Smithsonian Herpetological Information Services 122: 1 34. Wilson, L.D., Campbell, J.A.. 2000. A new species of the calamarina group of the colubrid snake genus Tantilla (Reptilia: Squamata) from Guerrero, Mexico, with a review of and key to members of the group. Proceedings of the Biological Society of Washington 113: 820 827. Wilson, L.D., Johnson, J.D. 2010. Distributional patterns of the herpetofauna of Mesoamerica, a biodiversity hotspot. In: Conservation of Mesoamerican Amphibians and Reptiles, p. 30 235. Wilson, L.D., J.H. Townsend., J.D. Johnson. Eagle Mountain Publishing, LC, Eagle Mountain, Utah, USA. Wilson, L.D., Mata-Silva, V. In press. Snakes of the genus Tantilla (Squamata: Colubridae) of Mexico: Taxonomy, distribution, and conservation. Mesoamerican Herpetology. Wilson, L.D., Meyer, J.R. 1981. Systematics of the calamarina group of the colubrid snake genus Tantilla. Milwaukee Public Museum Contributions in Biology and Geology 42: 1 25. Zweifel, R.G. 1960. Results of the Puritan-American Museum of Natural History Expedition to western Mexico. 9. Herpetology of the Tres Marías Islands. Bulletin of the American Museum of Natural History 119: 77 128. Accepted by Miguel Vences