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Mimic Glass Lizard Research Paper

Systematics: Described originally as Anguis ventralis by Carolus Linnaeus in 1766 from a specimen sent to him by Alexander Garden from "Carolina." Neill (1949) restricted the type locality to the vicinity of Charleston, South Carolina. The genus Ophisaurus was first used for this species by Daudin (1803). No subspecies are recognized. See the Ophisaurus attenuatus account for additional remarks on the use of the name in the Virginia literature.

Description: A slender, snakelike, legless lizard reaching a maximum snout-vent length (SVL) of 306 mm (12.0 inches) and a maximum total length of 1,083 mm (42.6 inches) (Conant and Collins, 1991). In Virginia, maximum known SVL is 290 mm (11.4 inches) and maximum total length is 604 mm (23.8 inches, specimen with incomplete tail). Tail length/total length of lizards with complete tails was 65.2-69.6% (ave. = 67.4, n = 2) in the Virginia sample. Tail length was 1.9-2.3 x body length. A deep, lateral groove is present on each side of the body.

Scutellation: Scales smooth, squarish to rhomboidal in shape, overlapping, and glossy; scale rows around midbody between lateral grooves 15 (40.0%, n = 5) or 16 (60.0%); ventral rows 10; ven- trals 105-107 (ave. = 105.8 ± 0.8, n = 5); scales along lateral groove 106-109 (ave. = 107.0 ± 1.4, n = 5); infralabials 10/10 (60.0%, n = 5) or 11/11 (40.0%); supralabials 10/10 (60.0%, n = 5) or 11/11 (40.0%); supranasals present; frontonasal separated from rostral; preanal scales 7; mental single; postmentals 2.

Coloration and Pattern: Dorsum often with a broad tan stripe (6 scales wide) that may extend to tip of tail; no dark, narrow middorsal stripe; brown dorsal scales in large adults may be edged in black and have numerous small white dots; 1-2 dark black or greenish stripes occur on each side above lateral groove; a white area lies between them and lateral groove; dark stripes broaden with age and old individuals nearly uniformly peppered green (or black) and white above lateral groove; black and greenish scales tipped in white on lower posterior corners only; no stripes below lateral grooves; venter of body and tail white; 3-7 vertical white bars bordered by black on neck and head between eye and lateral groove. The green color changes to black in preservative, but otherwise museum specimens are patterned as described. The fragile tail is easily broken and the regenerated portions are brown.

Sexual Dimorphism: The single adult male from Virginia (290 mm SVL) was larger but had a similar number of scales along the lateral groove (108) compared with the three adult females (230-277 mm SVL, ave. = 253.3 ± 23.5; scales 106-109, ave. = 106.8 ± 1.5). Sexual dimorphism index was -0.14. There are no apparent sexual differences in color and pattern.

Juvenile: Juveniles have little black, greenish, or white pigment on the dorsum except for 1 dark, narrow lateral line. The tan dorsum lacks a middorsal stripe, and the black lateral stripes extend to the tip of the tail. The vertical white bars on the side of the head and neck are pronounced. Immature individuals at least as large as 120 mm SVL retained juvenile coloration. Size at hatching was 123-139 mm total length (ave. = 128.7 ± 9.0, n = 3) (Schwab, 1992).

Confusing Species: This species may be confused only with Ophisaurus attenuatus, which has dark stripes below the lateral groove and lacks the vertical white bars on the side of the neck and head.

Geographic Variation: McConkey (1954) listed an average of 103.7 ± 2.7 (98-109, n = 50) scales along the lateral groove for the species rangewide. The count for the small Virginia sample averaged slightly higher.

Biology: Eastern Glass Lizards are found in pine flatwoods, mesic hammocks, wet meadows, maritime forests, and damp grassy areas in sandy environments, as well as near marshes (McConkey, 1954; Martof et al., 1980). The few lizards found in Virginia have been either in maritime forests or in grassy areas near marshes. Hamilton and Pollack (1961) noted numerous individuals being plowed out of loamy soil in Alabama. Palmer and Braswell (in press) reported this species to be active in early morning and at dusk in North Carolina. McConkey (1954) noted that O. ventralis is probably crepuscular. The seasonal activity period is unknown. Virginia specimens were collected March through August.

Ophisaurus ventralis forages underground and in grass cover. A single, large grasshopper (Orthoptera) was found in an immature female from Virginia. Hamilton and Pollack (1961) reported the following prey types from Alabama and Georgia: caterpillars, bush katydids, grasshoppers, mole crickets, cockroaches, ground beetles, scarab beetles, darkling beetles, click beetles, termites, common lacewing, isopods (pillbugs), crayfish, spiders, millipedes, centipedes, earthworms, mollusks, Little Brown Skinks (Scincella lateralis), an unidentified skink (Plestiodon), Southeastern Crowned Snakes (Tantilla coronata), Northern Brownsnakes (Storeria dekayi), and mammal hair, possibly the white-footed mouse (Peromyscus). They also found that five individuals had remains of other O. ventralis in their stomachs (cannibalism) and that one had eaten eggs of a conspecific. Predators of this species are unknown, but probably include feral pigs (Sus scrofa) in the Virginia portion of its range.

Females of this species are oviparous and lay 5-15 eggs in June and July (Noble and Mason, 1933; McConkey, 1954; Mount, 1975; Gibbons and Sem- litsch, 1991). Nests are depressions in loamy and sandy soil, and females coil about the eggs during nesting (Mount, 1975; Gibbons and Semlitsch, 1991). Glass lizard females will not defend their eggs as will female skinks (Plestiodon), but will gather the eggs back into the nest if they are scattered (Noble and Mason, 1933). A female with eggs was found in Virginia on 10 August (Schwab, 1992) and a captive female laid eggs on 23 June (Schwab, 1988b). Clutch sizes were six and seven. Eggs measured 20.0-22.0 x 12.9-14.1 mm (ave. = 21.3 ± 0.6 x 13.3 ± 0.3, n = 13) (Schwab, 1988b, 1992). Three of the eggs found under natural conditions hatched on 19 August (Schwab, 1992).

The population biology of this species has not been studied. These lizards are very active. Basking occurs in open sun on the ground with only part of their body exposed. They will thrash about when caught, bite if they can, and autotomize the tail if it is held.

Remarks: The "joint snake" myth described in the Ophisaurus attenuatus account equally applies to this species.

Prior to 1954, all glass lizards were called Ophisaurus ventralis. McConkey published his monograph that year demonstrating that there were three species, not one (Palmer [1987] recently described a fourth species). His information led him to conclude that only O. attenuatus longicaudus occurred in Virginia. Ophisaurus ventralis was not known from Virginia until 16 May 1981 when C. A. Pague, D. A. Merkle, and I collected the first (DOR) specimen in False Cape State Park (Pague et al., 1983).

A juvenile specimen of O. ventralis, found on a road near Aspen, Charlotte County, in March 1983 by the late R. N. Bader (pers. comm.), is considered an unintentional release. Bader reported that bales of hay had recently been brought in from South Carolina and the lizard may have rafted to Virginia in one of them.

Conservation and Management:Ophisaurus ventralis is listed as threatened under Virginia law (Mitchell and Pague, 1991b). Both federal and state authorities on whose land this species occupies should have active management plans to protect this element of our natural heritage. This management should include protection and maintenance of all grassy habitats near marshes. All plans for development of waterfowl impoundments and alteration of any grassland habitat should be critically reviewed for impacts on populations of this lizard. An inventory of southeastern Virginia should be conducted with appropriate capture techniques to determine whether this species occurs in other locations. All aspects of its population biology should be studied for information useful to the development of realistic management plans.

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Photo Credit: John Jensen

SCIENTIFIC NAME: Ophisaurus mimicus (Palmer)

OTHER NAMES: Legless Lizard, Glass Snake.

STATUS: Uncommon to rare, secretive, and possibly threatened throughout. Three documented occurences from southern portion of Alabama's Dougherty Plain and Southern Pine Plains and Hills. HIGHEST CONSERVATION CONCERN.

DESCRIPTION: A long, slender, limbless lizard superficially resembling a snake, relatively recently described (Palmer 1987). Glass lizards distinguished from snakes by presence of a lateral fold along each side of body, moveable eyelids, a pair of ear openings, and scales reinforced with bony plates (osteoderms), making their bodies feel relatively rigid. Mimic glass lizards are easily the smallest of three native Alabama species of Ophisaurus,with a maximum snout-vent length (SVL) of 181 millimeters (7.1 inches) (Palmer 1987). The slender glass lizard and eastern glass lizard may exceed 300 millimeters (11.7 inches) SVL. Tails are extremely long, typically about two-thirds of full length unless shortened by injury; quite fragile and readily break owing to fracture planes in tail vertebrae (Palmer 1987). Only counting scale rows along the lateral fold can positively identify mimic glass lizards (<96 vs. >98 in other two) (Palmer 1987, Moler 1992b). Dorsal color tan to brown and may or may not have light and dark speckling. Usually a mid-dorsal dark stripe on body and most of tail, but may be faint. Narrow, lateral stripes present on most of tail and above fold on posterior portion of body. Lateral stripes below fold faint. Vertical bars may be present on side of neck. Belly is pale (Palmer 1987).

DISTRIBUTION: Lower Coastal Plain from southeastern North Carolina to the Pearl River in Mississippi; apparently not in peninsular Florida (Palmer 1987, Moler 1992). Alabama specimens exist from Baldwin, Covington, and Mobile Counties (Palmer 1987).

HABITAT: Apparently strongly associated with endangered longleaf pine-wiregrass ecosystem. Includes pine flatwoods, savannas, and hillside seepage bogs (Palmer 1987, Moler 1992, Palmer and Braswell 1995). A grassy groundcover is characteristic of most of the habitats harboring all glass lizard species, presumably giving them lateral surfaces important in locomotion, as well as providing cover for them and their prey.

LIFE HISTORY AND ECOLOGY: Very little known throughout distribution. Even more true in Alabama, since all known records are from preserved museum specimens collected prior to recognition of species. A female collected from Mississippi contained 11 enlarged ova (Palmer 1987). Nothing else known about their reproductive biology. Based on one observation from Florida, the black racer is the only known predator (Moler 1992), although others certainly exist. Prey likely consists of a variety of invertebrates, as has been documented for other Ophisaurus spp. Limited information suggests species is primarily diurnal and crepuscular, although a few individuals were collected at night (Palmer 1987, Moler 1992). Slightly more than 60 percent of distribution-wide collections to date were made April to June, although specimens have been collected in every month but January and February.

BASIS FOR STATUS CLASSIFICATION: Inability to secure specimens from appropriate habitats since the species was taxonomically recognized is a legitimate cause for concern. However, their similarity in appearance to other, more common glass lizards could have reasonably led less observant biologists or naturalists to misidentify observed or captured specimens. This would not be surprising since many preserved museum specimens required relabeling following original discovery and description. The most recent specimen from Alabama was collected in 1976. The drastic loss and alteration of the longleaf pine-wiregrass ecosystem in Alabama and elsewhere has significantly reduced the available habitat seemingly needed by this poorly known animal. Public lands offer the best opportunity for rediscovering mimic glass lizards in the state, since most private lands within their presumed distribution have been converted to tree farms, agricultural fields, pastures, or residential and urban establishments. Fire suppression has further limited favorable habitat by promoting dense forest canopies incapable of supporting sufficient grass groundcover.

Author: John B. Jensen

http://www.conservationsoutheast.com/mimicus.htm