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CHAPTER 1

Species Accounts

The remainder of this book describes squamates as a major radiation of amniotes (terrestrial, egg-laying or live-bearing vertebrates), each family found in Alabama, and each of the state's species within each family. Presentation of each family, subfamily (for colubrid snakes), genus, species, and subspecies is in the order of appearance within the keys provided rather than listed alphabetically. Important genetic variation supported by published analyses is discussed within each species account. Each species or subspecies account has distinct sections that we describe below.

KEYS

Keys are tools designed to aid in identification of organisms. These tools present paired descriptions, one of which will conform to an individual organism of interest and the other description will not. At the end of each consistent description is a number indicating the next couplet to be considered. This process of making dichotomous choices is followed until a final description identifying the organism of interest is reached. We include taxonomic keys for the squamates of Alabama and take the unusual step of dispersing these keys throughout the accounts rather than including a single key. We do this to place information close to sections of text for which the keys are most useful. Keys to the major lineages of squamates appear at the end of the description of the group Squamata, and keys to the families of squamates appear at the end of the description of each major squamate lineage. When necessary, keys to genera are placed at the end of the description of each family, keys to species appear at the end of descriptions of each genus, and keys to subspecies are placed at the end of the taxonomy section of the appropriate species account.

NAMES

The generic, specific, subspecific, and common names applied are, in most cases, those listed in Crother (2017). However, a few designations, such as our treatment of Lampropeltis getula, represent personal choices that are our recommendations for taxonomic allocations given uncertainty in phylogenetic estimations.

PHOTOGRAPHS

We have benefitted from the talents of a large number of photographers. Where possible, we have selected images that show key features rather than those that have the best background or artistic composition. When the location of the specimen photographed is known, we identify it.

DESCRIPTIONS

Our descriptions are intended to provide sufficient information to enable the reader to distinguish a particular taxon from all others occurring within the state. Each description is based on a composite of specimens representing variation within Alabama and surrounding states. Because nature is variable, it should be kept in mind that occasional individuals belonging to the described taxon will not conform to the descriptions presented here.

ALABAMA DISTRIBUTION

In addition to a general statement describing the distribution of each species or subspecies occurring within Alabama, a map is included depicting its range in the state. Solid dots on the maps indicate localities of a) specimens the authors have examined, b) photo-vouchered specimens submitted to the Alabama Herp Atlas Project, c) occurrences documented in the databases of the Alabama Natural Heritage Program and/or ADCNR State Lands Division, Natural Heritage Section, and d) literature records believed valid. Each record has been georeferenced and plotted to the greatest possible precision. For taxa that are not found throughout the state, we include a shaded region indicating the likely limit to its distribution within Alabama. The state distribution maps also include black and white insets (lower right corner) showing the approximate distribution of each taxon within North America. These are derived from public data developed through two sources: the International Union for the Conservation of Nature (IUCN 2014) and the USGS Gap Analysis Program (GAP). In some cases, these maps were further modified to better reflect current information.

HABITS

Here, we provide description of habitat specialization, seasonal patterns of activity and reproduction, mating strategies of males and females, and major diet items. In general, this section is designed to summarize where and when each species is likely to be active and what activities make the species detectable by humans. Additionally, we describe the timing and duration of each major growth stage in the life cycle of the species.

CONSERVATION AND MANAGEMENT

In this section, we describe the current conservation status of each species or subspecies in Alabama. Alabama's squamates are generally threatened by habitat loss and fragmentation, loss of natural community integrity, and, in the case of large snakes, direct persecution. Because conservation issues are likely to increase in the future, we summarize human activities that might imperil each species or subspecies as well as those activities that are likely to enhance populations. Similar data are provided for taxa that have conservation status within the state, and for these, we provide information on key public properties that will play crucial roles in long-term maintenance of Alabama's imperiled herpetofauna. In developing the State Wildlife Action Plan (Division of Wildlife and Freshwater Fisheries, Alabama Department of Conservation and Natural Resources 2005), the state of Alabama used the findings from its 2002 Nongame Symposium, which assembled scientific experts to compile the best data on Alabama's wildlife and used those data to identify those species most in need of conservation action. The Nongame Symposium's Amphibian and Reptile Subcommittee reconvened in 2012, identifying five lizards and ten snakes as being of immediate conservation need (Priority 1 or 2, on a scale of 1 to 5; Mirarchi, Bailey, Haggerty, Best 2004), and we summarize the subcommittee's recommendation in each species account.

TAXONOMY

We accept the concept that species are lineages that are discovered through careful analysis of variation in the characteristics of organisms. These discoveries arise from creation of phylogenetic trees built from character data. Under this species concept, any diagnosable terminal branch is sufficient to discover a new species. Additionally, we accept the concept that taxonomic groups at any level of classification should be monophyletic so that such groups will carry the additional evolutionary information that members of the group are more closely related to other group members than they are to any organism that does not belong to the group. In practice, ancestral species might survive through the branching process, generating some lineages that are not monophyletic (de Queiroz 1998). Such species present challenges for determining species boundaries, and the decisions that we make for the boundaries of Alabama's species undoubtedly will suffer from this challenge.

For squamates, color patterns, conformation of scales, counts of scales, and shapes of appendages are external features that traditionally have been used to diagnose species. To a lesser extent, features of the skeleton and muscles are used as well. However, use of these morphological characteristics requires collection of large series of specimens because differences between some forms are based on differences in modes of scale counts. Such counts have been provided by Mount (1975), and we do not repeat them here. Instead, we focus on diagnostic characteristics that allow identification of animals in the field. A knowledge of these characteristics and of general anatomical directions will be needed to use the keys that we provide.

To these traditional characters, we have added information from publications describing the mitochondrial and nuclear genomes. These sequence data have the advantage of allowing rapid development of data sets that are much larger than those based on morphology. Offspring inherit the mitochondrial genome entirely from the female side of the family tree, while the nuclear genome captures information about gene flow associated with both parents. For this reason, phylogenetic trees based on the mitochondrial genome are not guaranteed to be concordant with those based on the nuclear genome. Data on the mitochondrial genome are particularly voluminous because they are cheap and easy to procure. These data are particularly important in phylogeographic studies, a field of biogeography that uses patterns of evolution within species that are discernible by analysis of molecular data. Now, such studies are common for Alabama's squamates, and the intraspecific lineages generated by such studies likely will allow us to discover new taxa that were not evident from analysis of traditional morphological data. This creates an exciting environment for taxonomists because so many new lineages may be available for discovery, and such discoveries tell important stories about how Alabama's rich biodiversity was generated (e.g., Soltis et al. 2006). It also creates a scary environment for authors of field guides, such as this one, because of the likelihood that the guide will be obsolete before it is published. Because of this, we attempt to describe all lineages supported by character data, including the mitochondrial genome, and, therefore, that might indicate speciation events awaiting taxonomic recognition.

Mount (1975) was exemplary in recognizing important subspecific variation within Alabama. That these taxonomic distinctions are important is supported by the elevation of a large number of subspecies to species status, largely based on accumulating molecular data but clearly supported by traditional characters. Because of this, we retain subspecies that are based on characters that show apparently significant geographic discontinuities. Phylogeographic studies frequently find imperfect concordances between subspecies boundaries based on morphology and boundaries of mitochondrial lineages; this discordance frequently is used to argue against traditional subspecific boundaries (e.g., Burbrink et al. 2000). In fact, this trend is so strong that large numbers of lineages have emerged that represent numbered or lettered clades on phylogenetic trees (e.g., Jackson and Austin 2010). Where possible, we attempt to align subspecific names with numbered or lettered clades and use such alignment to retain most subspecific categories. In some cases, molecular data, in association with subspecific designations that appear to be based on clinal variation, are used to reject previously recognized subspecies. If no taxonomic names are available for clades discovered within phylogenetic studies, then we retain named, numbered, or lettered clades described in such studies.

Lizards and Snakes — Squamata

Squamates, the living lizards and snakes, comprise 70 families containing about 9,900 species, making this the second-most species-rich radiation of land vertebrates. Only birds, with about 10,000 species, exceed the squamate radiation in species richness. As might be expected of such a diverse lineage, squamates exploit an amazing variety of habitats and display divergent foraging and reproductive modes. Many squamates are essentially ground-surface dwellers (e.g., Horned Lizards of the genus Phrynosoma), but some spend virtually their entire lives underground (e.g., Wide-snouted Wormlizards of the genus Rhineura), while others are almost completely arboreal (e.g., anoles of the genus Dactyloa), and a few are strongly aquatic with no need to return to land (e.g., Yellowbellied Seasnakes of the genus Pelamis).

Organizing the taxonomy for such a large group has been a challenge in herpetology. Fortunately, some clarity is beginning to emerge in that all squamates, with the exception of the enigmatic family Dibamidae, consistently cluster into one of four major monophyletic clades. Here, we follow the parsimonious analysis of morphological data summarized by Gautier et al. (2012) in classifying squamates. We prefer this treatment because of its extensive coverage of both taxa and characters and because it provides essential data from fossils. However, this treatment is challenged by extensive molecular data that recover different numbers of major monophyletic groups and find different phylogenetic histories among these groups (e.g., Wiens et al. 2010; Vidal and Hedges 2009; Pyron et al. 2013). However, because morphological data, coupled with fossil information, overturned similar previous challenges from molecular data (e.g., Gautier et al. 1988), we place our support on the morphological data by recognizing four major squamate groups: Iguania (iguanians), Gekkota (gekkotans), Scincomorpha, and Anguimorpha with snakes (Serpentes) evolving as the sister group to Anguimorpha.

A basal divergence separates the group Iguania — a lineage of squamates with relatively short bodies, relatively long legs, and tongues used in prey capture — from all others, which have tongues that are used to locate prey. The next divergence separates the group Gekkota, a lineage with specialized eyes for night vision, from all other squamates, which are characterized by relatively long bodies, relatively short limbs, and a forked tongue designed for detecting chemicals via a well-developed vomeronasal (Jacobsen's) organ. Among derived squamates, a divergence event occurs between those forms that have tongues covered with large plate-like structures (Scincomorpha) and those forms that retain a deeply forked projectile tongue (all others). Finally, a split occurs separating Serpentes, a species-rich group of squamates with highly modified vision and hearing, developed because the ancestral form was a burrower (Conrad 2008) or was aquatic (Lee 2005b), from Anguimorpha, a group of terrestrial predators retaining typical reptile eyes and ears but with lower jaws modified for prey capture. These major taxa will guide our presentation of Alabama's squamate fauna.

Limbs of many squamates are well developed, especially within iguanians. However, each of the other major lineages has representatives that have lost limbs in association with burrowing into loose soil, swimming, or crawling through grasslands. In forms that burrow, modifications of the eyes and ears occur because vision becomes practically useless within burrows and high-frequency sounds are not transmitted easily through soil. So, these radiations all contain lineages that look and act like snakes, including the lineage that eventually becomes true snakes (Gautier et al. 2012).

Food habits of lizards and snakes are equally diverse. Although rare, some forms, such as Green Iguanas (Iguana), are herbivorous and have specialized structures, such as slicing teeth, a muscular proventriculus (gizzard), elongate small intestine, and enlarged caecum, designed to digest foliage. Others are frugivorous, such as Chuckwallas (Sauromalus), which are famous for consuming the fruits of cacti. However, most squamates are predators, consuming animals as small as collembolans (Vitt et al. 2005) to as large as sun bears (Fredriksson 2005). Additionally, squamates may specialize on an extremely reduced array of prey. For example, some consume centipedes almost exclusively (e.g., Black-headed Snakes of the genus Tantilla) or consume any item small enough to fit in the mouth (e.g., Cottonmouths of the genus Agkistrodon), including road-killed animals (DeVault and Krochmal 2002).

Finally, reproductive modes of lizards and snakes are diverse. All forms have internal fertilization that is effected by insertion of an everted hemipenis, a unique copulatory structure of male squamates, into the cloacal opening of a female. This process frequently involves elaborate visual and olfactory cues that allow males to find females and females to select from available mates. Many forms, such as anoles (Dactyloidae), lay eggs without modifying the environment when creating a nest and provide no further parental care. In other forms, such as Glass Lizards (Ophisaurus), the female constructs a nest and then attends the eggs, likely driving away predators. Still other forms retain fertilized eggs in the uterine tract and develop a placenta, an anatomical feature that allows the female parent to provide protection and nutrients for the developing offspring. Such viviparous forms have developed independently at least 108 times within squamates (Blackburn 2006), suggesting strong selective pressure to protect the offspring during their early development.

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Excerpted from "Lizards and Snakes of Alabama"
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