Friday, January 6, 2017

Environmental DNA Detection of the Golden Tree Frog

The Bromeliad-dwelling Treefrog or the Golden Tree Frog, Phytotriades auratus was long thought to be restricted to two of Trinidad's sky islands. However, in 2015 Rivas and Freitas found it in Eastern Venezuela's Paria Peninsula. Now, an investigation has located another sky island locality in Trinidad - Chaguaramal. Torresdal et al. (2016) used environmental DNA (eDNA) to detect the presence of the frog in its bromeliad microhabitat. Phytotriades are known to use the water tanks of the bromeliad Glomeropitcairnia erectiflora. This is a huge strap-shaped leaf plant that is epiphytic and often three meters or more above the ground. Previous studies of the frog required ripping the plants apart to find the frog; now a water sample can be take from the plant and tested for the frog's DNA. The researchers tested 29 bromeliads, 23 of these tested positive for the presence of P. auratus. Additionally, two P. auratus were observed and in two of the plants tested, the Dwarf Marsupial Frog, Flectonotus fitzgeraldi, was also observed. The test distinguishes between species of frogs. The eDNA test will provide used data without destroying the microhabitat of this species, and allow conservation efforts to monitor the species distribution.


Citations

Rivas GA, De Freitas M. Discovery of the critically endangered golden tree frog, Phytotriades auratus (Boulenger, 1917), in Eastern Venezuela, with comments on its distribution, conservation, and biogeography. Herpetological Review. 2015; 46:153–157.

Torresdal JD, Farrell AD, Goldberg CS (2017) Environmental DNA Detection of the Golden Tree Frog (Phytotriades auratus) in Bromeliads. PLoS ONE 12(1): e0168787. doi:10.1371/journal.pone.0168787

Tuesday, January 3, 2017

Turnip-tailed Gecko, Thecadactylus rapicauda


Size. To 220 mm in body length. In mainland South America this gecko is primarily a tree-trunk dweller, but it will colonize buildings. The exception appears to be building that have already been colonized by the invasive African House Gecko, Hemidactylus mabouia. Thecadactylus has an average body temperature of 26.9 C and were similar to air and substrate temperatures, suggesting the species is a thermal conformer. Thecadactylus, like many other geckos has a clutch size of one egg, and the female lays multiple clutches in a short period of time.

Twig Anole, Anolis tigrinus

A Tobago Anolis tigrinus
Tobago Anolis tigrinus Peters, 1863 is a small anole that belongs to the ecomorph group referred to as twig anoles.  The following description is based on Ugueto et al. (2009) On mainland Venezuela females may reach 58 mm and males 55 mm in body length. Head elongate with large, tuberculate scales;  the supraoculars are also large and the supraorbital semicircles are usually in contact, but may be separated by 1 scale; interparietal and supraorbital semicircles are usually in contact, rarely separated by 1 scale; a  distinct occipital knob is present. Dorsal scales are small and smooth; 63–97 scales along the middorsal line from axilla to groin; 94–114 scales around midbody; ventrals slightly larger than dorsals, roundish and completely smooth; 57–84 scales along the midventral line between axilla and groin. Dorsal coloration has a lichen-like appearance, changing from brown to mossy green during metachrosis; dark vertebral, rectangular spots, lateral light round, large spots and/or oblique lateral blackish lines are usually present. Dewlap in males large extending close to mid venter with more or less horizontal rows of single scales; pale whitish anteriorly, pale yellow medially and orange postero-inferiorly with pale scales; females with a smaller dewlap, just reaching between the insertion of arms and  lightly beyond the axilla; with moderately separated, horizontal rows of single scales; pale orangish or grayish with conspicuous (usually horizontally elongated) black spots and pale scales.

Anolis tigrinus appears to be a central Venezuelan Coastal Range-Tobago endemic. However, we also have photographic evidence that A. tigrinus is present on Trinidad. Also see this blog post for more on its discovery on Tobago.

Ugueto GN, Rivas G, Barros T, Smith EN. A revision of the Venezuelan anoles II: redescription of Anolis squamulatus Peters 1863 and Anolis tigrinus Peters 1863 (Reptilia: Polychrotidae). 2009. Caribbean Journal of Science. 45(1):30-51.

Tegu or Matte, Tupinambis cryptus (Family Teiidae)


Our observations of this lizard suggest they use secondary forest, savannas, and human modified habitats. We have not observed them in primary forests proper, but at the forest edge. It may avoid dense forest because of the low number of basking sites. Like other species of Tupinambis, it is a dietary generalist. We have observed this lizard investigating caiman nests, forging along streams, on the floor of secondary forests, and in mangroves; usually while tongue flicking and probing the leaf litter with their head. This lizard is most readily observed foraging under the bird feeders at the Asa Wright Nature Center where they scavenge pieces of fruit.

Everard and Boos (1975) report it feeding on leatherback turtle eggs, ground nesting birds (including nestlings and eggs). They trapped itat Waller Field in Trinidad as well as Chaguaramas, Aripo-Cumuto, the Turure Forest, and Bush Bush Forest while studying the mongoose over a six year period. Traps were baited with chicken remains. At the Waller Field study site 56 specimens were trapped during a 23 week period. In a mark and release study involving 40 animals they had ten recaptures; time between capture and recapture ranging from 1–86 days. The animals moved between 0.0–1.2 km (X=404 m) and they estimated 79.9 (r=116.3–43.5) lizards inhabited the 104 ha study site. Trinidadian folklore (Everard and Boos, 1975) states that the young hatch during thunder storms, this suggests Beebe (1945) observed females depositing eggs in termite nests. Females excavate a chamber in a termite nest (often in arboreal situations), deposit their eggs, and the termites re-seal the nest chamber. The eggs hatch and the hatchlings escape when the termite nest softens during heavy rains. When disturbed their first defense response is to escape into vegetation or a burrow, but if cornered they raise their body and posture with stiffened legs while hissing and threatening with an open mouth. They will drop their tails and we have found shed tails in the field.

Barbados Anole, Anolis extremus (Family Dactyloidae)

Anolis roquet var. extremus Garman 1887: 35
Anolis extremus — Schwartz & Henderson 1991: 262

Distribution. The Barbados anole (Anolis extremus) is native to Barbados, but introduced to Saint Lucia and Bermuda, Trinidad and Huevos I. It does not appear to have survived the introductions on Trinidad or Huevos.

Diagnosis. Males have pale lavender to blue-gray heads, with blue eyelids. Their body is a deep green with dark markings and occasionally white spots, and ventral surfaces are yellow. Females are smaller and duller in color and may have a mid-dorsal stripe. Photo by Postdif.


Creer, D. A., Queiroz K., Jackman TR, Losos JB, Larson A. 2001. Systematics of the Anolis roquet series of the southern Lesser Antilles. Journal of Herpetology 35 (3): 428-441

Garman, S. 1887. On West Indian reptiles. Iguanidae. Bull. Essex Inst. 19: 25-50.

Lazell, J.D. 1972. The anoles (Sauria: Iguanidae) of the Lesser Antilles. Bull. Mus. comp. Zool. Harvard 143 (1): 1-115.

Schwartz, A. & Henderson, R.W. 1991. Amphibians and Reptiles of the West Indies. University of Florida Press, Gainesville, 720 pp.

Speckled Anole, Anolis aeneus (Gray)

Distribution. Anolis aeneus is endemic to Grenada and the Grenadines, its populations in Trinidad and Tobago (as well as Guyana) are introduced.

Males reach a body length of 77 mm, females are smaller reaching about 55 mm. Coloration is usually gray, olive, or chocolate-brown, mottling or speckles. Note that it has a bluish eye which will distinguish it from most other Anolis on Trinidad and Tobago.

Natural History. Anolis aeneus uses a wide range of habitats including open areas (Hailey et al., 2009), with substrates of mainly bushes and walls (White & Hailey, 2006) and it is usually seen in urban areas in Trinidad and Tobago. However we have found it in disturbed secondary forests on Tobago.

Gray, J. E. 1840. Catalogue of the species of reptiles collected in Cuba by W. S. MacLeay, esq.; with some notes on their habits extracted from his MS. Ann. Mag. Nat. Hist. (1) 5: 108-115.

John, RR., Hedman HD, Powell R. 2012. Anolis aeneus. Catalogue of American Amphibians and Reptiles (892): 1-11.

Lazell,J.D. 1972. The anoles (Sauria: Iguanidae) of the lesser Antilles. Bull. Mus. comp. Zool. Harvard 143 (1): 1-115

Malhotra, A. & Thorpe, R.S. 1999. Reptiles & Amphibians of the Eastern Caribbean. MacMillan, London & Oxford

Schwartz, A. & Henderson, R.W. 1991. Amphibians and Reptiles of the West Indies. University of Florida Press, Gainesville, 720 pp.

Simmons, P. M., B. T. Greene, K. E. Williamson, R. Powell and J. S. J. Parmerlee 2005. Ecological interactions within a lizard community on Grenada. Herpetologica 61 (2): 124-134.

Williams, E.E. Quesnel, VC. Kenny, J S.; Underwood, G. 1959. The anoles of the Eastern Caribbean (Sauria, Iguanidae) Part. I. Preface; Part II. Two sibling species of anoles in Trinidad; Part. III. Revisionary notes. Bull. Mus. Comp. Zool. Harvard 121 (5): 185-226.

Streak Lizard, Gonatodes vittatus (Family Sphaerodactylidae)

Male (top), female (bottom).


Size: 33−34 mm SVL, both sexes about the same size; tail about 50% of SVL. Identification. A small lizard with a cylindrical body and tail; smooth, small, uniform scales on dorsum; digits slender and end in a claw. Males with bright white vertebral stripe bordered in black, extends to tail tip; body otherwise red-brown to blue gray; females heavily spotted, vertebral stripe indistinct; but colors are variable and may change with social situations. Lamellae on fourth toe 19−23. Like other Trinidad and Tobago Gonatodes dorsum with tiny granular scales, belly with larger overlapping scales. Perhaps, the most commonly seen lizard in Trinidad and Tobago. Similar species are mostly other Gonatodes that can be distinguished on the basis of coloration, hatchlings are minute, but tend to have numerous small orange spots distinguishing them from the tiny, usually striped Mole’s Gecko. Distribution: northern Colombia, Venezuela (including the Isla de Margarita and other coastal islands) and Trinidad and Tobago. Habitat: Forest-edge, savanna, and edificarian habitats; abundant in coconut trash; open shaded surfaces, on tree trunks and garden walls; does not hesitate to enter occupied houses. Biology: Diurnal but may be active at night, ambush predator and active forager. Unlike some of its relatives this species often basks in direct sunlight. Diet small arthropods including ants, beetles, spiders, dipterous larvae, isopods. Reproduction: Gonatodes frequently curl their tails over back in a scorpion-like posture, a female displaying the tail-raised posture toward a male may then be displaced by the male, the function of the display is poorly understood. Fertile eggs produced for 5-6 months after the last mating; eggs laid on palm trunks covered with fallen fronds, under rocks, and in crevices or buildings; like anoles and many other geckos, probably lays clutch of a single egg in rapid succession. Males engage in tumbling fights over territories or display locations.

Black &White Worm Lizard, Amphisbaena fuliginosa Linnaeus

Amphisbaena fuliginosa Linnaeus

Distribution. Colombia, Venezuela, Guyana, Suriname, French Guiana, Trinidad, Brazil, Peru.

Natural History. May be active any time of the day in leaf litter or loose soil. Uses savanna and forest habitats. Feeds on arthropods, and may be associated with leaf cutter ant nests.

Double-headed Worm Lizard, Amphisbaena alba Linnaeus 1758

Amphisbaena alba Linnaeus 1758: 229.

Distribution. Panama, Guyana, Surinam, French Guiana, Venezuela, Colombia, Ecuador, Brazil, Peru, Bolivia, N Paraguay, Trinidad. Probably island wide on Trinidad.

Size. Adults reach 609 mm in total length. The tail is 10% or less than the body length.

Natural History. On Trinidad it has been associated with leaf cutter ant nests (Riley et al (1985). A Brazilian study (Colli and Zamboni, 1999) reports on this species natural history. Diet includes plant material as well as small vertebrates. Reproduction occurs in the dry season in Brazil, smallest reproductive males are 422 mm, smallest reproductive females 457 mm. Clutch size 8-16.

Andrade, Denis V.; Nascimento, Luciana B.; Abe, Augusto S. 2006. Habits hidden underground: a review on the reproduction of the Amphisbaenia with notes on four neotropical species. Amphibia-Reptilia 27 (2): 207-217

Colli, G.R. & Zamboni, D.S. 1999. Ecology of the Worm-Lizard Amphisbaena alba in the Cerrado of Central Brazil. Copeia 1999: 733-742

Gans, C. 1962. Notes on amphisbaenids (Amphisbaenia, Reptilia). 5. A redefinition and bibliography of Amphisbaena alba Linné. American Museum Novitates (2105): 1- 31

Gans, C. 2005. Checklist and bibliography of the Amphisbaenia of the world. Bull. Am. Mus. Nat. Hist. 289: 1-130

Gans, Carl 1967. A check list of recent amphisbaenians (Amphisbaenia, Reptilia). Bull. Amer. Mus. Nat. Hist. 135:61-106.

Linnaeus, C. 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata. Laurentii Salvii, Holmiæ. 10th Edition: 824 pp.

Rivas, Gilson A.; César R. Molina, Gabriel N. Ugueto, Tito R. Barros, César L. Barrio-Amorós 2012. Reptiles of Venezuela: an updated and commented checklist. Zootaxa 3211: 1–64

Starace, Fausto 1998. Guide des Serpents et Amphisbènes de Guyane. IBIS Rouge Editions, Guadeloupe, Guyane, 450 pp.

Vanzolini, P. E. 1955. Contribucoes ao conhecimento dos lagartos Brasileiros da familia Amphisbaenidae Gray, 1825 5. Distribuicao geographica e biometria de Amphisbaena alba L. Arquivos do Museu Nacional 42: 683-706

Vanzolini, P.E. 1974. Ecological and geographical distribution of lizards in Pernambuco, northeastern Brasil (Sauria). Papeis Avulsos de Zool. 28(4): 61-90.

Monday, January 2, 2017

Garman's Thin-toed Frog, Leptodactylus validus (Family Leptodactylidae)

This species occurs on the Lesser Antillean islands of St. Vincent and Bequia, Grenada, and is widespread on the continental islands of Trinidad and Tobago. It has been recorded from sea level up to near 730m asl. This is a terrestrial and nocturnal forest and forest edge species found in road side ditches, flooded grassy habitats, and secondary forests near streams. It is one of the most commonly heard, but less often seen frogs on the islands. Parent Leptodactylus validus stand watch over their offspring.

Charlotteville Litter Frog, Pristimantis charlottevillensis (Family Craugastoridae)

Charlotteville Litter Frog, Pristimantis charlottevillensis is a Tobago endemic restricted to the forested habitats on Tobago's Main Ridge. Adult males may reach 31 mm, female 47 mm. Males call from the leaf litter or from the vegetation. This terrestrial frog is nocturnal.

Trinidad Thin-toed Frog, Leptodactylus nesiotus (Family Leptodactylidae)

Trinidad Thin-toed Frog, Leptodactylus nesiotis (Family Leptodactylidae)

This frog is known from Trinidad from a few specimens collected in the southwest peninsula and Nariva Swamp. It is endemic to Trinidad.