Sunday, July 9, 2017

Small headed Treefrog, Dendropsophus microcephalus

A small yellow frog: 12-17 mm SVL; with the canthus forming a distinct ridge, and a light line from the anterior of eye to nostril. Dorsal skin smooth, ventral skin and skin under are thighs granular. Fingers with some webbing mostly reduced to bases of digits and lateral fringe; toes moderately webbed. H.goughi has a rounded canthus and lacks a lateral cream or enamel stripe. To distinguish it from H. m. misera: both species have a canthal ridge, but H. minuscula is much smaller, calling males tan and red, with side stripe that makes this species unique, and readily identified in the field.

Size. A small tree frog: males are typically 18-25 mm SVL (mean: 22 mm) and females 21-28 mm SVL (mean: 25 mm).

Identification. Dorsal skin smooth and variable in color, ranging from pale yellow and orange-brown. Venter is white, with distinct tubercular skin on the belly and thighs, which are used as complementary adhesive surfaces. Tubercles on the ventral thigh are yellow.  Reproductively active males have a yellow throat pouch and, when calling, are solid yellow in color. Dorsal markings are variable, often consisting of a network of darker brown speckled lines giving a ‘marbled’ appearance or creating an H-shaped marking between the shoulders. A dark interorbital line or blotch is common. A narrow brown line extends laterally from the nostrils, along with the canthal ridge, over the eye to midway down the body. This gives the frog’s head a distinctive triangular appearance. Dark brown flecks are scattered across the dorsum, the forelimbs and the lower hind limbs, with these forming two to three indistinct transverse bars on the shin in many individuals. Thighs are translucent and yellow with no pigmentation. Eyes are prominent, with a bronze iris and horizontally elliptical pupils. Eye diameter is generally greater than or equal to the eye-nostril distance. The tympanum is distinct and speckled with gold flecks. Webbing on the fingers is reduced, toes have moderate webbing. Fingers and toe tips are yellow, with expanded discs to aid with climbing at the ends of the digits. The feet have prominent subarticular tubercles, which are yellowish in color. 

Vocalization. Males call from marginal vegetation, emergent grasses and shrubs, usually at heights of 20-50 cm above the water. Dendropsophus microcephalus call in large assemblages, often with multiple species present (including D. goughi, D. minusculus, L. validus, S. ruber, H. punctatus, P. trinitatis and S. lacteus).  The call is a high-pitched “skrreeet, riti-titi-titi-titi” with the last phase of the call having an almost sawing rhythm.

Similar species. Small-headed Treefrog is one of three closely related frogs found in Trinidad (see also D. goughi and D. minusculus) all of which are small and yellowish in color. Dendropsophus microcephalus has a distinct pale line that runs from the back of each eye to just over the nostril, which makes the head appear almost pointed in shape. Dendropsophus minusculus is smaller as an adult, and has an enamel colored lateral stripe. The belly of Dendropsophus goughi is yellow rather than white, it has white markings on the rump and heels, and a rounded canthus all are absent in the other two dendropsophids. See the other species descriptions for comparison. 

Biology. Diet includes ants, spiders, ticks and mites. Arachnids are a particularly important element of their diet and can comprise over 80% of prey. Soil organisms, such as collembolans are a significant prey item for the wet season. Adults and tadpoles are vulnerable to predation by a wide range of both vertebrate and invertebrate predators, including snakes, (Leptophis), large spiders, and water bugs. Crabs are thought to be significant predators of both the adult frogs and their eggs in Trinidad. Dendropsophus microcephala is an opportunist breeder, with reproductive activity triggered by significantly increased rainfall. In Trinidad, males have been recorded calling throughout the rainy season with peaks in activity in June-July. Frogs can be found calling in mixed-species choruses, in the north of Trinidad, particularly alongside D. microcephalus which often outnumbers them significantly. In Trinidad, calling males are often attended by silent satellite males which attempt to intercept females attracted to the breeding ponds. 
Distribution. Widely distributed in Middle and South America and has been recorded from Mexico, Guatemala, Honduras, Nicaragua, Costa Rica, Panama, Colombia and Venezuela as well as from Trinidad and Tobago. The island subspecies is D. microcephalus misera, and is also known from the llanos of Colombia and Venezuela. In Trinidad, D. microcephalus is found island wide, at low elevation sites ranging from the southwestern peninsula to Chaguaramas. On Tobago, it occurs at scattered localities but widespread.

Habitat. The Small-headed Treefrog is highly adaptable and is often found in disturbed habitats, forest edges, and savanna habitats. Breeding sites include temporary ponds, shallow roadside ditches, and flooded pasture land as well as swamps and marshes. They are rarely recorded from more enclosed, forest habitat.    

Biology.  Nocturnal, but can be found during the day close to their calling sites, concealed in vegetation. Diet consists of small flies, spiders, and cockroaches. Dendropsophids fall prey to a wide range of predators including bats, snakes, other frogs and large invertebrates such as water bugs, fishing spiders, and centipedes. 

Calling can be heard throughout the year as long as water is available. Studies in Colombia and Venezuela suggest that D. microcephalus is an opportunistic breeder, with activity increasing during and after rainfall. Eggs are laid on or near the surface of the water, usually attached to emergent vegetation. Spawn is present as a small cohesive mass, with each dark-colored egg within its own jelly capsule. Reported clutch sizes range from 150-400 eggs, though clutches of around 200 eggs are more typical for Trinidad. 

Tadpoles are tiny and black-brown when they first hatch. Later stage tadpoles are distinctive, and colorful in appearance with a silver-white belly flecked with black, a yellow-brown dorsum and tail, which are mottled and marbled with black. The tail is deep and leaf-shaped and tapers off to a distinct filament, which is barred with black bands. A dark-brown stripe runs from the nose through the eye and along the side of the tadpole’s body. Tadpoles are filter-feeders and are often observed in open water, hanging vertically and maintaining their position by rotational movements of the filamentous tail tip. Development is rapid, with metamorphosis occurring at about six weeks. Maximum lengths are around 35 mm. Newly metamorphosed froglets are about 10 mm SVL.

Conservation status. Least Concern. Data suggests it is both abundant and increasing in numbers. Taxonomic status of subspecies needs clarification. It is less susceptible to chytridiomycosis than many other species. There is some suggestion, therefore, that it might act as a ‘reservoir taxa’ and it may be important to consider the nature of interactions that might occur in mixed species assemblages at breeding sites.

The Paradox Frog, Pseudis paradoxa (Family Hylidae)

Adults are 45-75mm in total length. Body is short and stout; eyes dorsolateral; dorsal and ventral skin; fingers free of webbing, toes heavily webbed. Dorsum green anteriorly, brown to green posteriorly; flash marks on the posterior surface of the femur. Ventral immaculate white. Pseudis paradoxa has the largest, or near largest tadpoles known when compared to adult size. Tadpoles are 220 mm (3 to 4 times longer than adult frogs). As currently defined it is known from the following countries: Argentina, Bolivia, Brazil, Colombia, French Guiana, Guyana, Paraguay, Peru, Suriname, Trinidad (unknown from Tobago), and Venezuela. Usually found in open marshy areas with floating vegetation, in permanent and temporary ponds. Calls can be heard day and night and consist of a sequence of 8-11 pulses, but frogs are very wary during the day. At night they can be seen floating on the surface and grasping vegetation with their hands. Mating may be stimulated by rainfall. Eggs are green and laid along the shore among aquatic plants.

Tungara Frog, Engystomops pustulosus (Family Leiuperidae)

Previously known as Eupemphix pustulosus trinitatis and Physalaemus pustulosus.

Size: small terrestrial frogs, males 28 mm, females 32 mm SVL.

Identification: Dorsal skin highly tubercular, arranged more or less in longitudinal rows; lateral skin also tubercular. Dorsum brown-grey with darker spots along tubercle rows. Ventral skin granular, tan to yellow. Dorsal surface of hind limbs cross-barred. Snout pointed in dorsal view, rounded in profile. Tympanum indistinct. Small triangular parotoid gland present. All digits lack webbing and adhesive discs. Toes have a slight lateral fringe.

Similar species: The size, shape, wariness, and vocalizations of tungara frogs make them readily distinguishable.

Distribution and habitat: The genus Engystomops contains nine species, distributed from southern Mexico to northern South America and on to Bolivia.

Vocalization: There are two components to the call, a resonant ‘poong’ followed by a series of short ‘chucks’- ch,ch,ch. Complexity added by the chucks helps to attract females, but it also attracts predatory bats, so in the presence of bats, the male frogs simplify their calls.

Research indicates that the E. pustulosus is a very widespread species, from Mexico, south through Central America and Amazonia. 

Although there is considerable variation there is no firm basis to subdivide the population into different species. E. pustulosus is very common in both Trinidad and Tobago, mainly in lowland grasslands, forest fringes and in towns as a human commensal (often co-occurring with Leptodactylus fuscus).

Biology: Diet not reported. Mating pairs generate white floating foam nests, about 6-8 cm, in the open at the edges of ponds, choked ditches, even water-filled tire ruts. Each nest contains 300-500 creamy white eggs which hatch into the water below after about 2 days. 

Tadpoles are capable of metamorphosis after about three weeks, at which time they reach a maximum length of about 22 mm. Body rounded, tail tapered. Overall coloring pale gray/brown. These tadpoles are cryptically colored and tend to be found in the sediment at the bottom of temporary pools. Newly metamorphosed individuals are about 9 mm SVL and look like miniature adults.

Conservation status: Least Concern on account of its wide distribution, tolerance of a wide range of habitats, and presumed large population.

Knudsen’s Thin-toed Frog, Leptodactylus knudseni (Leptodactylidae)

Leptodactylus knudseni is widely distributed in the greater Amazon basin from Bolivia and Brazil north to Colombia, Venezuela, and the Guianas. Its presence on Trinidad is based upon a single specimenMCZ 8663. R. R. Mole collected or presented, the specimen to the MCZ, in May 1915. This species is in the pentadactylus Group and early references to Leptodactylus pentadactylus on Trinidad probably refer to this species. Barbour (1914) suggested that L. pentadactylus may have been exterminated on Trinidad because of its culinary value. The species presence on Trinidad has been reported only once in the early literature from the Island (Mole and Urich, 1894a) and they suggested it may have been exterminated by the introduction of the mongoose. Hardy (1982) suggested a member of the pentadactylus Group may also occur on Tobago, recounting Ober’s (1898) description of a gourmet frog dinner on Tobago and a subfossil frog femur from a cave. The presence of an extant population of this frog on either island is not substantiated in this work.

Suriname Toad, Pipa pipa (Family Pipidae)

Size: Large aquatic frogs, up to 200 mm SVL; sexual dimorphism not reported.

Identification: Dorsal skin dark brown/gray with many small dark brown tubercles which end in small sharp points; ventral skin paler. Head and body flattened and wide. Head almost triangular in shape with a short straight-ending snout; eyes very small; tympanum is hidden; mouth as wide as the head, no tongue. Forelimbs are long and slender, with long unwebbed fingers terminating in four small projections, each sub-divided. Hind limbs powerful, with wide feet, toes fully webbed. 

Vocalization: The call is said to be a subtle ‘click’ made underwater.

Similar species: Pipa pipa cannot be confused with any other species.

Distribution and habitat: The genus Pipa contains seven species inhabiting wetlands through much of South America. P. pipa is often known as the Suriname Toad, but outside the Guianas, the Pipa Toad is a more appropriate common name. P. pipa is found from Peru and Bolivia north to the Guianas and Trinidad, but not Tobago. Widely distributed in Trinidad at lower elevations in swamps and slow-moving turbid streams.

Biology: The habits of Pipa Toads have not been studied in the wild. In aquaria, adults sit motionless on the bottom, with their arms held forwards and wide apart; they capture fish very rapidly by opening the mouth wide and apparently shoveling the fish in using the arms. During mating, the fertilized eggs become individually embedded in the hormonally softened skin of the female’s back; each egg is covered by a thin capsule and develops there until around the stage of metamorphosis; the young emerge as fully metamorphosed miniature adults, or they may retain a short tail for a few days.
Tadpoles: If a free-swimming tadpole stage occurs, it is at Gosner stage 42 or later, with the tail regressing over a few days.

Conservation status: Least Concern on account of its abundance and wide distribution. Note that recent efforts to find this frog on Trinidad have not been successful.

Orinoco Crocodile, Crocodylus intermedius (Family Crocodylidae)

This species is listed here because it is a potential waif from the nearby Orinoco River. It is unlikely to be found in Trinidad or Tobago. Size. 6.8 m. Diagnosis. Snout elongated and pointed, adult individuals lack a pre-orbital hump present in C. acutus; the symphysis of the lower jaw extends to the sixth tooth in this species, but to the fourth or fifth tooth in C. acutus. It can be separated from the common caiman, Caiman crocodilus by having the fourth tooth in the lower jaw visible (it is not visible in the caiman) and it lacks the interorbital ridge present in caimans. Distribution is restricted to the Orinoco drainage of Colombia and Venezuela. It may occasionally show up as a waif on the shores of Trinidad and nearby islands, including Chacachacare Island and Grenada. Thus, there is no evidence that this species occurs on Trinidad or Tobago, but because the Orinoco species may occasionally wander down river to these islands, there is a possibility of its occurrence. Life History. During the wet season individuals may move great distances, but during the dry season, they restrict their activity to deep pools that remain in rivers. Juveniles use still water with dense vegetation. Females mature at 250 cm; nesting occurs early in the dry season and eggs hatch during the initial rise in water level at the start of the wet season; eggs are laid in a hole excavated in either an eroded river bank or a beach. Individual females are known to reuse nesting sites. Photo by Greg Hume.

The Neotropical Pipe Snake, Anilius scytale (Linnaeus 1758)

The Neotropical Pipe Snake, Anilius scytale, is discussed here because it was been reported from Trinidad as early as 1858. This species is in its own family, the Aniliidae and is generally considered to represent an ancient lineage of snakes, and it is one of only a few clades of snakes to retain teeth on the premaxillary bone, a trait considered to be primitive. It is ovoviviparous. The diet consists of elongated amphibians and other reptiles. The pipe snakes' body is cylindrical and uniform in diameter, the tail is exceptionally short, all characteristics of a specialized burrowing snake; the color pattern is red and black bands (no yellow or white bands); eyes are degenerate and embedded in large ocular scales. This species is found in Amazonian South America, Guyana and probably Trinidad. Total length is about 70 cm. The photograph is a museum specimen from Guyana. This species is probably not part of the Trinidad fauna.

Three-lined Snake, Atractus trilineatus (Family Dipsadidae)

Atractus trilineatus Wagler 1828
Rhabdosoma lineatum — Duméril & Bibron 1854: 105.
Rabdosoma trivirgatum Jan 1862.
Rabdosoma punctatovittatum Jan 1862.
Rabdosoma trivirgatum — Jan 1865.
Rabdosoma punctatovittatum — Jan 1865.
Rhabdosoma lineatum — Garman 1887: 280.

Syntypes: MNHN, now lost [Rabdosoma punctatovittatum]. Lectotype: RMNH 48, a 205 mm female, designated by Hoogmoed, 1982: 135. Type locality: Caracas, Distrito Federal, Venezuela.

Distribution. This is a lowland Guiana endemic known from northern Venezuela and the Guianas, and is present on both Trinidad and Tobago, and is known from the Bocas as well as Little Tobago.
Males are gray-brown, females are red.

Size. 350 mm SV L, 285 mm TL. Diagnosis. Snout and tail sharply pointed, dorsum brown-gray with three or four light lines; scales smooth in 15 rows at mid-body. Perhaps most easily confused with Atractus univittatus (only known from Tobago and main land Venezuela) which has 17 scale rows at midbody or Epictia tenella which has cycloid scales in 14 rows at mid-body.

Life history. A fossorial snake of forests and savannas as well as urban environments. Diet includes worms and insects. Reproduction. Females are known to lay 3–5 eggs, in March, May, and August suggesting it may reproduce year round. Defense behavior. The sharply pointed tail is used as a probe and can startle a potential predator. This snake is eaten by Erythrolamprus aesculapii and coral snakes.

Anonymous 2008. OPINION 2210 (Case 3365): Atractus Wagler, 1828 and Atractus trilineatus Wagler, 1828 (Reptilia, Serpentes): conserved. Bull. Zool. Nomencl. 65 (23):

Beebe, William 1946. Field notes on the snakes of Kartabo, British Guiana, and Caripito, Venezuela. Zoologica 31: 11-52

Boos, H.E.A. 2001. The snakes of Trinidad and Tobago. Texas A&M University Press, 270 pp.

Claessen, H. 2003. De slangen can de Guyana’s. Deel iv. Lacerta 61 (1): 19-27

Duméril, A.M.C., G. BIBRON & A.H.A. DUMÉRIL 1854. Erpétologie générale ou Histoire Naturelle complète des Reptiles. Vol. 7 (partie 1). Paris, xvi + 780 S.

Garman, S. 1887. On West Indian reptiles in the Museum of Comparative Zoology at Cambridge, Mass. Proc. Amer. Philos. Soc. 24: 278-286.

Gorzula, Stefan & Senaris, J. Celsa 1999. In: Contribution to the herpetofauna of the Venezuelan Guayana. I: a data base. Scientia Guaianae, Caracas, No. 8 [1998], 269+ pp.; ISBN 980-6020-48-0

Hoogmoed, M. S. 1982. Nomenclatural problems relating to Atractus trilineatus Wagler, 1828. Zoologische Mededelingen Leiden 56 (10): 131-138

Hoogmoed, M.S. & J.M. Savage 2006. CASE 3365: Atractus Wagler, 1828 and Atractus trilineatus Wagler, 1828 (Reptilia, Serpentes): proposed precedence over Brachyura Kuhl, 1820 and Brachyorrhos kuhli Boie in Schlegel, 1826. Bull. Zool. Nomencl. 63 (1)

Hoogmoed, M.S.; Savage, J.M. 2007. Case 3365. Atractus Wagler, 1828 and Atractus trilineatus Wagler, 1828 (Reptilia, Serpentes): proposed conservation. Bulletin of Zoological Nomenclature 64 (1): 60-63

Jan, G. 1865. Iconographie générale des ophidiens. 11. Livraison. J.B. Bailière et Fils, Paris

Johnson, M.L. 1946. Herpetological Notes from Trinidad. Copeia 1946 (2): 108

Lancini AR. & Kornacker PM. 1989. Die Schlangen von Venezuela. Armitano Editores C.A., Caracas, 1-381

Lynn, W.G. 1959. Some Reptiles and Amphibians From Trinidad. Herpetologica 15 (3): 113-117

Martins M. Oliveira M E. 1993. The snakes of the genus Atractus Wagler (Reptilia: Squamata: Colubridae) from the Manaus region, central Amazonia, Brazil. Zool. Meded. 67 (1-26): 21-40.

Mertens, R. 1972. Herpetofauna tobagana. Stuttgarter Beitr. zur Naturkunde nr. 252 22 pp.

Passos, P. & Fernandes, R. 2008. A new species of the colubrid snake genus Atractus (Reptilia: Serpentes) from the central Amazon of Brazil. Zootaxa 1849: 59–66

Passos, P., R. Fernandes and Borges-Nojosa, D.M. 2007. A New Species of Atractus (Serpentes: Dipsadinae) from a Relictual Forest in Northeastern Brazil. Copeia 2007 (4): 788–797

Passos P. Ramos LO, Pinna PH, Prudente ALC 2013. Morphological variation and affinities of the poorly known snake Atractus caxiuana (Serpentes: Dipsadidae). Zootaxa 3745 (1): 035–048

Passos, Paulo; Philippe J. R. Kok, Nelson R. de Albuquerque, and Gilson A. Rivas 2013. Groundsnakes of the Lost World: A Review of Atractus (Serpentes: Dipsadidae) from the Pantepui Region, Northern South America. Herpetological Monographs 27 (1): 52-86

Rivas, GA, Molina CR, Ugueto GN, Barros TR, Barrios- Amorós CL 2012. Reptiles of Venezuela: an updated and commented checklist. Zootaxa 3211: 1–64

Roze JA 1961. El genero Atractus (Serpentes: Colubridae) en Venezuela. Acta Biologica Venezuelica 3 (7): 103-119

Wagler,J. 1828. Auszüge aus seinem Systema Amphibiorum. Isis von Oken 21: 740-744

Atractus fuliginosa (Family Dipsadidae)

Size. 291 mm SVL, 334 mm TL, tail 14.7% SVL.
Identification. A small, gray snake with a single stripe dorsally, a uniform cream venter, and 17 rows of smooth scales on the body. Rostral pentagonal and visible from above; loreal and preocular fused; two postoculars; seven upper labials; six lower labials; ventrals 163; cloacal plate single; 32 paired subcaudals.
Similar species.  Perhaps most easily confused with Atractus trilineatus which has three well-defined longitudinal stripes and 15 scale rows.
Distribution. A Caribbean Coastal Range species found in northern Venezuela and known from three specimens collected on Tobago’s Main Ridge (unknown from Trinidad).
Habitat. A poorly known forest dwelling snake that uses the leaf litter.
Biology. Unknown. Diet is unknown. This snake is known from three specimens from Tobago, but on the mainland, Venezuela is well represented.

Mapapie Balsain, Bothrops atrox (Family Viperidae)

The Trinidad population of Bothrops cf. atrox is in need of systematic reassessment. It is a member of a widespread and trans-Andean species complex. It ranges from Yucatan southward through Middle America to the Pacific versant of Colombia and Ecuador and across northern Venezuela to the Orinoco River and occurs on Trinidad. This snake is a serious threat to human health should they be bitten.

Machete Savane, Chironius carinatus (Family Colubridae)

Size. 1.5 m SVL, tail 58-79% SVL. Diagnosis. An olive green snake with a yellow ventral surface. Eyes exceptionally large. Dorsal scales in 12 rows at mid body, reduced posteriorly to 10; scales smooth except those on either side of vertebral row which are strongly keeled in males and weakly keeled in females. Each dorsal scale tipped with black. Dorsum olive green, venter yellow, blue or both; chin and labials yellow. The 12 dorsal scale row count distinguishes this snake from all other T&T snakes, except the long-tailed machete, which has more ventral scales (161–174) than this species (146–167) and a relatively longer tail. 

Distribution. C. carinatus is probably widespread in northern South America and in Trinidad. 

Life History. A forest and forest-edge snake, which descends to the ground to forage during the day and sleeps in bushes and trees; uses primary and secondary forests. Diet. Hylid frogs are frequently taken as prey. Defense. Kinking its body so that it mimics twigs or leaf petioles is common; it does not hesitate to compress the anterior portion of its body and strike; compression of the body exposes pink skin that contrasts to dark scales. Other common names. Machete savanne, yellow machete, golden tree snake.

Macajuel, Boa constrictor (Family Boidae)

Boa constrictor Linnaeus 1758:215

Distribution. Widespread, ranging from Colombia to northern Argentina, the Lesser Antilles, and Trinidad and Tobago. It is present in the Bocas on Monos Island, Gasparee Grande.

Size. 4 m TL, females larger than males, hatchlings about 0.6 m. Description. Nasals separated by at least four or five tiny internasals, a character that will readily distinguish it from all other snakes in the area. Upper labials number 16–25, lower labials number 20–28; these lack heat sensing pits found in Epicrates and Corallus. Smooth dorsal scales are in 76–95 rows; ventrals number 214–248; anal plate single; single subcaudals number 49–60. Dorsum tan or gray with dark red-brown transverse marking. Colors change posteriorly, tan areas become cream, or almost white, and brown transverse blotches become red. Brown stripe from snout passes through the eye and extends to first transverse band. Males have larger preanal spurs than females. 

Life History. A habitat generalist: rainforest, secondary growth, savannas, and cultivated areas; often in close proximity to human habitations. Diet. A variety of vertebrates are eaten, including: rodents (squirrels, mice, rats, agouti), dogs, cats, marsupials, mongoose; birds; and reptiles (Ameiva, iguanas, tegu lizards). Reproduction. Courtship occurs in October-March; litters of 21–64 are born May-September.

Tuesday, May 16, 2017

The phylogeny of the luminous lizard of Trinidad - a new genus for the luminous lizard

The systematics and ecology of most microteiid lizards of the subfamily Cercosaurinae are poorly known. The subfamily is primarily associated with the Andean highlands where they inhabit humid forest leaf litter.  The genus Riama is the most speciose genus of the Neotropical lizard family Gymnophthalmidae. It contains more than 30 montane species that range throughout the northern Andes, the Cordillera de la Costa in Venezuela, and Trinidad. In a recent paper Sanchez-Pacheco et al. (2017) present a phylogenetic analysis of Riama based on a total evidence approach and direct optimization of molecular and morphological evidence. Analyses use DNA sequences from four loci and 35 phenotypic characters. The dataset consists of 55 in-group terminals representing 25 of the 30 currently recognized species of Riama plus five undescribed taxa, including an endemic species from the Sierra Nevada de Santa Marta in Colombia, and 66 outgroup terminals of 47 species. Their analysis results in a well-supported hypothesis in which Riama is polyphyletic, with its species falling into three clades. The Tepuian Anadia mcdiarmidi nests within one clade of Riama, and the recently resurrected Pantodactylus nests within Cercosaura. Accordingly, the authors propose a monophyletic taxonomy that reflects historical relationships. Analysis of character evolution indicates that the presence or absence of prefrontals—a cornerstone of the early genus-level taxonomy of cercosaurines—is optimally explained as having been plesiomorphically present in the most recent common ancestor of Cercosaurinae and lost in that of the immediately less inclusive clade. Multiple independent reversals to present and subsequent returns to absent occur within this clade.
Gray (1858) described the genus Riama, and placed it in its own family (Riamidae) based on the new species Riama unicolor. Peters (1862) described Ecpleopus (Oreosaurus) striatus and Ecpleopus (Oreosaurus) luctuosus and assigned these species to Oreosaurus characterized as having striated dorsal scales while those in the closely related subgenus Proctoporus (P. pachyurus and P. unicolor), had smooth or keeled scales. Boulenger (1885) synonymized Gray’s Riama with Proctoporus and elevated both subgenera to genera. He defined Oreosaurus has having a wide band of small scales separating the ventral and dorsal scales, and Proctoporus as having the dorsal and ventral scales separated by a fold with granular scales. The diagnoses of the two genera are virtually identical, except for the lateral fold. Boulenger (1885, 1902, 1908) allocated six species to Oreosaurus (O. laevis Boulenger, O. luctuosus, O. ocellifer Boulenger, O. oculatus O’Shaughnessy, O. petersii Boettger, and O. striatus). And, Boettger (1891) described the Bolivian species O. guentheri. Andersson (1914) was unable to separate the two genera. Apparently, the fold Gray and Boulenger reported was an artifact of preservation (see Doan and Castoe, 2005). Thus, Andersson (1914) placed Oreosaurus in the synonymy of Proctoporus, an arrangement used into the early 21st century. Subsequently, Parker (1935) described Proctoporus shrevei from Trinidad. A species that would later gain the attention of science and the public for reportedly being luminescent (Roth and Gans, 1960; Knight et al. 2004).
Most species of Proctoporus were known from relatively few specimens. Uzzell (1958) noted more than half of the species were known from less than five specimens. Yet, after examining only 11 of the 16 recognized species, he attempted to define species groups within the genus. Uzzell (1958, 1970) placed P. luctuosus, P. laevis, P. oculatus, P. shrevei, and P. achlyens, a new taxon from Venezuela, in the luctuosus group. Uzzell defined the luctosus group as having: lateral scales smaller than dorsals and forming a wide band between dorsals and ventrals; males have ocelli in their pattern; four supraoculars; a divided palpebral; no median occipital; pregulars arranged in chevrons with the apices forward, not in transverse rows; limbs overlapping when adpressed; the absence of a continuous narrow granular band along the sides of the body. Uzzell argued that the characters occur in other species outside the group, but the combination is distinctive. He recognized two other species groups that are not directly related to the discussion here.
The three taxonomic groups (Uzzell, 1958, 1970) are allopatric with the Proctoporus luctuosus group occurring mostly in Venezuela and Trinidad, with one species, P. laevis, in Colombia, and another, P. oculatus from Ecuador. The P. pachyurus group occurs in central and southern Peru and Bolivia, and the P. ventrimaculatus group in northern Peru. Kizirian (1996) studied the Ecuadorian Proctoporus, and added nine new species to the previously described 16 species. Doan and Schargel (2003) described Proctoporus inanis from the Merida Andes of Venezuela.
Kizirian (1996) summarized the nomenclatural history of Proctoporus, but remarked that while the monophyly of the genus had been suggested it was not confirmed. Additionally, he recognized three available generic names (Emphrassotis O'Shaughnessy, Oreosaurus Peters, and Riama Gray) are in the synonymy of Proctoporus. Kizirian (1996) also points out that Burt and Burt (1931) designated the type species of Oreosaurus as Oreosaurus (Ecpleopus) luctuosus Peters. Later, Peters and Donoso-Barros (1970) designated the type species as Oreosaurus (Ecpleopus) striatus Peters. Presumably, this was because the striatus description precedes that of the luctuosus description in Peters (1862). Kizirian also commented that Peters and Donoso-Barros may be correct.  Too be clear, these two species were described in the same paper (Peters 1862) and the ICZN Code does not recognize page priority, but it does recognize the principal of the first reviewer, Article 24.22.2 (Ride, 1999). Given this rule, we consider Burt and Burt (1931) to be the first reviewer and Oreosaurus would have priority in the event luctuosus should require a new genus. 
The first attempt to establish a phylogenetic classification of the Cercosaurini tribe of gymnophthalmids recognized two clades. Doan and Castoe (2005) resurrected the genus Riama to accommodate one of the clades of the polyphyletic genus Proctoporus. Using their classification Proctoporus contains five species from the central Andes of Peru and Bolivia. The remaining 24 species formerly belonging to Proctoporus were placed in Riama. Following this arrangement Gray’s genus Riama occurs throughout the Andes of central Peru, Ecuador, Colombia, and Venezuela, the Cordillera de la Costa of Venezuela, and Trinidad’s Northern Range. Rivas et al. (2005) described Riama rhodogaster from Venezuela’s Peninsula de Paria, and considered it the sister to Trinidad’s P. shrevei.
Sanchez-Pacheco et al. (2017) results have implications for patterns of distribution among major biogeographical units, and especially the connection between the Sierra Nevada de Santa Marta in Colombia, the Cordillera de la Costa in Venezuela, the island of Trinidad, and the tepuis (Venezuelan Guyana and Guyana Shield). Their inclusion of the undescribed Sierra Nevada de Santa Marta endemic Oreosaurus “Sierra Nevada”, two endemic species from the Cordillera de la Costa (O. achlyens and O. “Venezuela”), the Trinidadian endemic O. shrevei (Aripo Northern Range), and the tepui endemic O. mcdiarmidi allows a test of previous biogeographical hypotheses. Although each of these highland complexes has a unique geological history, cumulative phylogenetic evidence suggests an ancient connection between them. Species form monophyletic groups despite the considerable geographical distances that separate them. For example, our analysis recovers O. “Sierra Nevada” as the sister of the remaining species of Oreosaurus, followed by O. mcdiarmidi. Oreosaurus achlyens is the sister of O. shrevei + O. “Venezuela”. The distribution of Oreosaurus (Sierra Nevada de Santa Marta, CC, Trinidadian high-lands and tepuis) constitutes a biogeographical pattern (as a whole) not repeated in other vertebrates. This distribution strongly implies an ancient biogeographical connection between the Sierra Nevada de Santa Marta and the Cordillera de la Costa as part of the explanation for the origin of the montane Sierra Nevada de Santa Marta endemic vertebrate fauna.
Cordillera de la Costa which includes the island of Trinidad extends eastwards along the Caribbean coast from the Andean Cordillera de Merida and it has two main sections. First, the Barquisimeto Depression separates the Central (locality of Oreosaurus achlyens and O. luctuosus) from the Cordillera de Merida. Second, the Cordillera de la Costa Oriental extends farther east along the coast toward the island of Trinidad, which lies 12 km off the northeastern coast of Venezuela. In turn, the Cordillera de la Costa Oriental consists of two separate mountain chains situated in extreme northeastern Venezuela: the Pen􀀁ınsula de Paria, the type locality of O. rhodogaster, and the massif of Turimiquire, locality of O. “Venezuela” (Rivas et al., 2005). The Cordillera de la Costa originally extended from the Merida Andes onto the island of Trinidad. Thus, the northern range of Trinidad, the type locality of O. shrevei, was stratigraphically contiguous with the coastal range of Venezuela during the Pliocene and Pleistocene. This connection facilitated the exchange of species through land connections. A Miocene downwarping event severed the land connection. Accordingly, the Cordillera de la Costa Oriental shares many species with Trinidad. 

Below is figure 3 from Sanchez-Pacheco et al. (2017) showing the distribution of the members of the genus Oreosaurus.

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Monday, January 23, 2017

Cuiver’s Dwarf Caiman, Paleosuchus palpebrosus

The Dwarf Caiman has males that are slightly larger than females (1.3-1.5 m); females reach about 1.2 m. They are distributed in northern and central South America from Trinidad southward to Paraguay. The Dwarf Caiman tends to use fast-moving streams in forested habitats that are cooler than stream in more open habitat,. The streams may be shared with the Spectacled Caiman. The Dwarf caiman is more terrestrial than the Spectacled Caiman, and can be observed sitting on the shoreline and using burrows. Dwarf Caimans are nocturnal hunters. Juveniles feed on insects, mollusks, crustaceans, fish frogs and their tadpoles. Adults have a similar diet but include small mammals. Their gizzard contains gastroliths (small stones) which mechanically break down the food into smaller pieces. On the mainland nesting occurs at the end of the dry season and the beginning of the rainy season in areas with warm climates. Clutches of 10-25 eggs are deposited in a nest made of soil, leaves, small branches, and other vegetation; and  constructed by both parents. The nest is usually small in diameter and height. Incubation is about 90 days. Parental care is minimal or absent until the nest is opened by the female when the young start to vocalize. After hatching the young stay under the nesting material for several days. Sexual maturity is reached at 1.1 meters in males and about one meter in females. These sizes are reached at about 10 years of age. Dwarf Caimans are social, and while they are sometimes solitary they may be found in pairs or small groups. Like other crocodilians, they communicate with sound, posture, movement, chemicals, and contact. Dominance hierarchies form within groups. Dominant individuals have access to mates, nest sites, food, and living space. Dominance is maintained by social signals and displays. Predators of these small crocodilians include cats, raptors, wading birds, snakes, and large fish. Conservation Status. The IUCN considers it a species of Least Concern, while CITES has listed it on Appendix II. This species was only recently discovered in south-central Trinidad.

Ali SH, Rampersad-Ali N, Murphy JC. 2016. The discovery of Cuvier’s Dwarf Caiman, Paleosuchus palpebrosus (Reptilia: Alligatoridae) in Trinidad. Living World, Journal of the Trinidad and Tobago Field Naturalists' Club. 2016 Nov 30.

Johnstone's Rain Frog, Eleutherodactylus johnstonei

Johnstone's Rain Frog, Eleutherodactylus johnstonei (Family Craugastoridae)

Males 17-25 mm, females, 17-35 mm. Dorsum brown or gray brown with one or two darker chevrons; a narrow middorsal stripe or a pair of broad dorsal stripes may be present;skin smooth to slightly tuberculate; distinct tympanum; small, rounded finger and toe disks; digits lack webbing. Native to Anguilla, Antigua and Barbuda, Barbados, Dominica, Grenada, Guadeloupe, Martinique, Montserrat, Netherlands Antilles, Saint Kitts and Nevis, Saint Lucia, Saint Vincent and the Grenadines; introduced into Aruba, Bermuda, Colombia, Costa Rica, French Guiana, Guyana, Jamaica, Panama, Trinidad, Venezuela. Males usually call from low vegetation in disturbed habitat, it seems to avoid forests and undisturbed environments. Reproduces throughout the year with most activity during the wet season. Clutches 10-30 unpigmented eggs covered in a thin layer of viscous mucus which undergo direct development; froglets have body lengths of about 4 mm. It takes about a year for the frog to reach sexual maturity. In the 1980's this frog was restricted to Port of Spain, it has now spread east along the Eastern Main Road to St. Augustine, and can be heard at Piarco Airport. It has now reached Tobago.