Eastern Indigo Snake

description

Our sample of OCIC specimens recovered four categories of temporal scales from both Atlantic and Gulf Coast lineages (Table 1). In 24 % of specimens, temporals conformed to the 2 + 2 formula that Krysko et al. (2016 b) described as being invariant (Fig. 1 A), with 38 % of specimens exhibiting an extra ventral temporal (Fig. 1 B), 23 % of specimens having extra dorsal and ventral temporals (Fig. 1 C), and 15 % of specimens exhibiting an extra dorsal temporal (Fig. 1 D). The frequency with which these four categories occurred differed between Atlantic and Gulf Coast lineage specimens (Table 1; χ 2 = 12.11.; df = 3; p <0.01), with Atlantic lineage snakes tending to have conditions with two dorsal temporals and Gulf Coast lineage snakes tending to have conditions with three dorsal temporals. Head shape, based on ANCOVA of head height on head length, did not differ between Atlantic and Gulf Coast lineages in either slope (Fig. 2; F = 0.07; df = 1; p = 0.79) or elevation (F = 0.48; df = 1; p = 0.49). Length of the dorsal posterior-most temporal, expressed as a proportion of head length, differed significantly among temporal categories (F = 18.34; df = 3; p <0.0001), with the dorsal poste

Patterns of head shape and scutellation in Drymarchon couperi (Squamata: Colubridae) reveal a single species

discussion

Our results reject the hypothesis that the Atlantic and Gulf Coast lineages of D. couperi (Krysko et al. 2016 a) are identifiable on the basis of aforementioned phenotypic characters. We reach this conclusion after examining the variables used by Krysko et al. (2016 b) to diagnose each lineage. Of the disparities that emerge between our analyses and theirs, the conformation of the infralabials is the most problematic. The figures presented by Krysko et al. (2016 b) and Enge and Krysko (2019) for the 6 th infralabial show great promise for diagnosing lineages. However, we were struck by how dissimilar the 6 th infralabial of Atlantic specimens appeared to be from the long and thin scale shape ascribed to them by Krysko et al. (2016 b, fig. 5 A). Our analyses demonstrate that the 6 th and 7 th infralabials differ in shape, that the shape of the 7 th infralabial conforms to the shape ascribed to the Atlantic lineage, and that the shape of the 6 th infralabial conforms to that ascribed to the Gulf Coast lineage. Given that it is unclear which of these scales was measured by Krysko et al. (2016 b) and that the range of variation of each scale within a sample of Atlantic lineage snakes e

Patterns of head shape and scutellation in Drymarchon couperi (Squamata: Colubridae) reveal a single species

materials_examined

examined snakes housed at the Orianne Center for Indigo Conservation (OCIC) that were raised as stock for repatriation efforts. Our sample included 58 individuals likely representing all three genetic populations associated with the Atlantic lineage (Atkinson, Bryan, Evans, Long, Telfair, Wayne, and Wheeler counties, Georgia, USA) and 16 individuals likely representing two of three genetic populations of the Gulf Coast lineage (Citrus, Highlands, and Marion counties, Florida, USA; lineages from Krysko et al. 2016 a; genetic populations from Folt et al. 2019 b). We photographed lateral or dorsolateral aspects of the head of each specimen including a millimeter ruler for scale. From the images, we categorized the condition of the temporal scales for each specimen based on four character states created by the number and position of the scales (Fig. 1). We generated a contingency table providing counts of specimens in each of the four categories for each lineage. We used Chi-square analysis to determine whether the relative proportions of temporal scale categories differed between the Atlantic and Gulf Coast lineages. Additionally, we measured total head length (posterior-most point of

Patterns of head shape and scutellation in Drymarchon couperi (Squamata: Colubridae) reveal a single species

description

Description of holotype. Adult male; Total Length 163.1 cm; Snout-vent Length 133.1 cm; Tail Length 30.0 cm; Head Length 51.3 mm; Head Width 25.2 mm. The relative head length (geometric shape variable; see Tables 2 and 3) is short (3.80) and relative head height is narrow (1.98). Supralabials 8 / 8 (left / right); Infralabials 9 / 9; Oculars 1 + 2 / 1 + 2; Temporals 2 + 2 / 2 + 2 (divided). The 7 th infralabial is relatively long (0.65) and narrow (0.26) (geometric shape variable; see Tables 2 and 3) and the temporal scale is relatively short (0.78). The 5 th and 7 th supralabials are in contact with each other. Two pairs of chin shields, both of which are in contact with each other; posterior pair slightly narrower than anterior pair. The rostral visible from above, broader than high. Dorsal scales smooth and in rows at Mid-Body 17, Anterior 17 and Posterior 15; Ventral Scales 184; cloaca undivided; Subcaudal Scale Total 59 (all divided). The specimen has faded from its likely original solid black dorsum. There is light pigment (likely reddish in real life) on the rostral, loreals, labials and chin shields that extend posteriorly onto the first three to four ventrals. The first 40

A cryptic new species of Indigo Snake (genus Drymarchon) from the Florida Platform of the United States