The lizard Anolis longitibialis is a species of anole found on Hispaniola, a Caribbean island comprised of the countries of Haiti and the Dominican Republic. Anoles are a diverse group of small, primarily arboreal, insectivorous lizard species found in the New World from North Carolina all the way to central South America and on the Caribbean islands. This species is a member of a Hispaniolan clade of anoles that are all considered members of the “trunk-ground” ecomorph class. Trunk-ground anoles are so named because they use low perches, such as tree trunks and large rocks, and will actively forage on the ground. Members of this ecomorph, which are similar in ecology and morphology, have evolved independently on several Caribbean islands, including Hispaniola. Anolis longtibialis belongs to the cybotoid radiation of anoles, which is a monophyletic group containing A. cybotes and roughly half a dozen other trunk-ground species. This species is primarily a rock dweller; it is at home on large boulders or perched along limestone cliff walls. Its distribution is relatively restricted in comparison with the other species in this clade. Anolis longitibialis was first identified on Isla Beata, a small satellite island off the southern coast of the Dominican Republic, where it is quite abundant. On Isla Beata it perches on broad cliff walls, and will use the crevices to hide. Schwartz (1979) reported a distinct subspecies discovered in the Jaragua National Park, in the southwestern Dominican Republic. Jaragua is composed mainly of dry forest, and there are patches of limestone rocks scattered throughout. This species perches on those rocks, as well as the surrounding vegetation.
Distribution: Hispaniola (SE Haiti, SW Dominican Republic), Isla Beata Anolis longitibialis longitibialis: Isla Beata.
Type locality: Isla Beata, República Dominicana. Anolis longitibialis specuum (HOLOTYPE MCZ 132370): Peninsula de Barahona.
Compared to other species in the cybotoid radiation, the rock and cliff-dwelling A. longitibialis is relatively restricted in its distribution. It can only be found in the southwestern Dominican Republic, in the southern lowland areas of Barahona and Pedernales provinces, and on the satellite island of Isla Beata.
Anolis longitibialis is a medium-sized anole, as males can reach 72 mm snout-vent length (SVL) and females 59 mm. This species is larger than most other cybotoids, although A. strahmi, from the Sierra de Baoruco, and A. haetianus, from the western Tiburon Peninsula in Haiti, can achieve larger body sizes. This species has a distinctive dirty yellow or mustard colored dewlap, which gets lighter, reaching a light orange or pale yellow, heading from the edge to the base. Typical patterning includes a brown dorsum with 4 transverse dumbbell-shaped blotches along the body, and usually a pair of sacral blotches. The throat is usually striped in females, but is not commonly streaked in males. Its large head has a sharp canthus and a low nuchal crest. For a more detailed description, see Schwartz (1979) or Schwartz and Henderson (1991).
For many years Anolis longitibialis was thought to occur only on Isla Beata, where it was first described. In 1969, however, Richard Thomas noticed that one putative female A. cybotes from the Barahona region of mainland Hispaniola was significantly larger than all of the others he had collected. An analysis of the lizard's morphological traits (body size and scale patterns) identified the female as A. longitibialis. This was the first confirmed observation of A. longitibialis on the main island, and it was subsequently followed by additional observations by Albert Schwartz, who found A. cybotes and A. longitibialis occurring sympatrically near Pedernales. Schwartz (1979) conducted a detailed analysis of the mainland populations, which he named A. l. specuum, a separate subspecies from the Isla Beata population.
Anolis longitibialis longitibialis Noble, 1923
Holotype: AMNH 24329 (American Museum of Natural History, New York City)
Type Locality: Isla Beata, Dominican Republic
Anolis longitibialis longitibialis males usually reach about 72 mm snout-vent length (SVL), while females reach 59 mm. The median dorsal scales are generally small, and the supraorbital semicircles do not touch, although the supralabial scales typically contact the subocular scales. There are 4-5 postrostral scales. The fourth toe (longest toe) has few expanded lamellae (15-21), and the dewlap ranges in color from light yellow to orange. Males rarely have streaked throats.
Anolis longitibialis specuum Schwartz, 1979
Holotype: MCZ 132370 (Museum of Comparative Zoology, Harvard University)
Type Locality: 17km NW of Oviedo Nuevo, Pedernales Province, Dominican Republic
As in A. l. longitibialis, males of this subspecies reach 72 mm in snout-vent length, while females reach 59 mm. This subspecies also has 4-5 postrostral scales. In contrast, however, A. l. specuum has larger dorsal and ventral scales. Its back is brown with 4 transverse dumbells, with sacral blotches not uncommon. While males don’t usually have streaked throats, females typically do. The dewlap ranges from a light orange to a dusky or mustard yellow.
The only sympatric species that is somewhat similar to Anolis longitibialis is A. cybotes, but these two species differ in many respects. Anolis cybotes is a stout and thickly built anole, while A. longitibialis is a much leaner animal. As its name suggests, it has a relatively long tibia, and its dewlap has a deep mustard color, unlike the pale yellow or cream dewlap of A. cybotes. Furthermore, A. cybotes is not found on Isla Beata, and so it is only sympatric with A. longitibialis in the Barahona region and, although they bear a general resemblance to each other, they can usually be differentiated even at a distance.
Anolis longitibialis prefers rocks and cliff crevices, though there have been some sightings of the species perching on other substrates, such as trees and fence posts. They usually perch within a meter and a half of the ground, often utilizing rocks, cliff walls, or other broad surfaces such as tree trunks. This species is xerophilic, and inhabits the dry forest of Jaragua National Park in the southwestern Dominican Republic. On Isla Beata, these anoles will be found on cliff walls and associated vegetation along the beach. They will also perch on sea grape trees within only a few meters of the surf. There is a dry scrub forest on Isla Beata, and they can be found there, as well.
Like most anoles, this species' diet consists primarily of insects. It will also eat arachnids along with millipedes and isopods. In addition, a broad taxonomic variety of insects have been found in their stomachs, including coleopterans (beetles), cockroaches, dipteran larvae, hemipterans, hymenopterans, lepidopterans, neuropterans (lacewings), orthopterans, and snails. Also ingested is shed skin, which anoles often eat, and plants, probably consumed unintentionally.
A study by Gifford et al. (2003) found that during the summer the diets of male and female A. longitibialis are predominated by lepidopteran larvae, which the authors hypothesized was an opportunistic exploitation of a seasonally abundant resource, as these larvae are common in the summer months. Further work by Fontenot et al. (2003) found that the diets of male and female A. longitibialis were more varied in January. Specifically, spiders and flies were the most important prey items for males, while ants and crickets were most important for females. No lepidopteran larvae were found in the guts of any animals in winter, suggesting that this species capitalizes on a seasonally abundant resource.
Anolis longitibialis shares its habitat with the Common Ameiva, Ameiva chrysolaema. While the anole perches within a meter and a half of the ground, A. chrysolaema is primarily a ground-dwelling lizard. Anolis longitibialis is also found with the Barahona Curlytail Lizard, Leiocephalus barahonensis, on piles of limestone rocks in Jaragua National Park, in the Barahona region of the southwestern Dominican Republic. In Jaragua, but not on IslA. longitibialis occurs sympatrically, though rarely syntopically, with A. cybotes, a closely related trunk-ground anole. In appearance these species are relatively easy to distinguish. However, they share some similarities in perching habits, despite early accounts reporting strong microhabitat differences between the two species. Anolis cybotes, which is more characteristically found on tree trunks, may sometimes be observed perching on rocks, and A. longitibialis may sometimes be observed on tree trunks and other vegetation. On Isla Beata the only other anole species that A. longitibialis occurs with is A. brevirostris, a small anole that is a member of the “trunk” ecomorph, but the latter is primarily restricted to tree trunks and branches and is not commonly found on the rocks that A. longitibialis tends to prefer. These species occur syntopically, especially on the sea grape (Coccoloba) trees lining the beach and in the dry forest.
Beuttell and Losos (1999) formally classified this species as a member of the trunk-ground ecomorph class. Trunk-ground anoles are medium-sized lizards that are usually found within a meter of the ground. They perch on broad surfaces, such as tree trunks and rocks. They have long hindlimbs and tails and are swift runners. Anolis longitibialis is a saxicolous, xerophilic species found most commonly perching on rocks or cliffs in hot and dry lowlands. Although this species is most commonly seen perching on rocks, it can also be seen perching on fence posts, tree trunks, fallen trees, branches, and vines. Like most anoles, this species is insectivorous, and it is not an uncommon species in places within its habitat where insects are presumably abundant, such as trash and waste piles, despite the proximity to humans. Vine snakes, among others, prey on A. longitibialis.
Life History and Behavior
Anolis longitibialis inhabits relatively hot and dry areas. It is restricted to the Barahona region of the southwestern Dominican Republic, and to the nearby offshore island of Isla Beata. On the Hispaniolan mainland A. longitibialis typically perches on piles of limestone rocks. When escaping a threat, it will run between these rocks and has also been observed running into the hollowed stumps of dead trees.
An analysis of testis size and juvenile abundance indicates that the reproductive season begin in June. Fontenot et al. (2003) found females still had shelled eggs and yolking follicles in January, suggesting that the reproductive period extends beyond the rainy season. Egg size is not correlated with female body size, and females can retain eggs.
Evolution and Systematics
Anolis longitibialis belongs to the cybotoid lineage of trunk-ground anoles from Hispaniola. Poe (2004) found fifty-eight morphological synapomorphies supporting the monophyly of the cybotoid group of trunk-ground anoles, including features like their broad heads and relatively long thighs.
A molecular study of the cybotoid anoles by Glor et al. (2003) found that the saxicolous species A. longitibialis and A. strahmi are sister taxa and that, along with A. marcanoi, they diverged early within the cybotoid radiation. Because of their shared ecology and sister relationship Glor et al. (2003) inferred that the common ancestor of A. longitibialis and A. strahmi evolved a rock-dwelling ecology. These authors hypothesized that this ecology evolved convergently in A. cybotes ravifaux, which may also use rocky outcrops on the small island of Isla Catalina, off the southeastern coast of the Dominican Republic. In particular, A. longitibialis, A. strahmi, and A. c. ravifaux have long hindlimbs, a trait often associated with a predominantly saxicolous lifestyle.
Physiology and Cell Biology
Anolis longitibialis lives in a hot and dry climate. As such, it encounters consistently high air temperatures, which it buffers by dwelling primarily in the shade, especially on large trees or in cave or crevice openings. It is active on partly cloudy or overcast days, but is fairly inactive on sunny days. Nonetheless, its body temperatures often exceed air temperatures. On both the Hispaniolan mainland and on Isla Beata, body temperatures of greater than 36 degrees Celsius have been recorded for this species.
Molecular Biology and Genetics
GenBank nucleotide sequences: AY263010; AY263009
GenBank protein sequences: AAP94310; AAP94311; AAP94312; AAP94313; AAP94314; AAP94315
As of February 2011 this species has not yet been assessed by the IUCN.