An addition to the herpetofauna of Tobago, Anolis tigrinus

Anolis cf tigrinus from Tobago. JCM

Since the 17th century the island of Tobago has been explored by a variety of naturalists including many people who examined the herpetofauna by actually doing field work , others who examined museum specimens, and some that did both. The island is relatively small (~ 300 sq km) but has the oldest protected mature forest in the western hemisphere.

One of the biogeographic puzzles surrounding Tobago is that it has no native members of the genus Anolis. It does have the Giant Crown Anole (Anolis richardii) which is thought to have been introduced from Grenada and it does have Anolis aeneus which appears to be a very recent introduction (probably in the last 20 years). Both of these species are associated with disturbed habitats. We should add that Little Tobago Island (97 ha) is also missing a native anole.

Trinidad, while it is a larger island (~4780 sq km), has only a single known species of native anole, Anolis planiceps (formerly known as Anolis chrysolepis planiceps). However it too has introduced anoles, (A. aeneus, A. trinitatis, A. wattsi, A. extremus, and probably at least another two or three species which we will discuss in a future post).

During the 2015 Tobago Bioblitz (October 24-25) we discovered a small anole, with a body length of about 34 mm, and a mossy green-grey, lichen-like dorsal pattern. Our preliminary results suggest this is Anolis tigrinus Peters. The coloration, body form (slender with short arms and legs) and the scale counts we did all suggest that this is A. tigrinus or something closely related to it.

Anoles come in ecomorphs depending on what microhabitats they exploit, there are trunk-crown ecomorphs (largest body size), trunk-ground ecomorphs (slightly smaller than the previous morph), twig morphs (smaller yet), and the grass-bush morph which is the smallest known morph.

The habitat and distribution of Anolis tigrinus given by Ugetto et al. (2009) was  premontane and montane forest from central Falcón and Yaracuy through Aragua, Distrito Federal, Vargas and Miranda to northern Anzoátegui and southwestern Sucre. Our Tobago record expands the range about 280 km to the northeast.

Anolis tigrinus is a small anole and usually consider a twig morph with males reaching a maximum body length of about 55 mm and females being slightly larger at about 58 mm. Twig anoles use the tips of branches in the crowns of trees, the smallest of perches. This allows them to feed where other, heavier bodied anoles cannot go and gives them a better chance at avoiding their vine snake predators (Oxybelis aeneus and Imantodes cenchoa).

The head is elongate and has relatively large, smooth scales. The supraocular area has a few enlarged scales surround by many smaller, more granular scales. The supraorbital semicircle scales on both sides usually make contact, but may occasionally be separated by one scale; interparietal and supraorbital semicircle scales usually make contact. Dorsal scales small and smooth and from two rows of slightly enlarged scales along the middorsal line.

The most recent review of Anolis tigrinus was done by Ugetto et al. (2009) and they describe its habitat as humid and very humid premontane forests between 980 and 2087 m in Venezuela. It occurs along forest edges and invades the forest for short distances and they are often about three meters off the ground. The individual we found was on the ground in an edge situation and was likely blown off the tree by the wind or fell when it was being chased by a predator. The highest point on Tobago is about 550 m and this specimen was taken at about 400 m ASL. Thus, the Tobago population differs in inhabiting a lower elevation than other clade members.

Ugetto et al. (2009) also reported that male tigrinus have an unspotted dewlap, which is decidedly larger than that of females, and that males are easily recognized by the presence of large, postanal scales and the base of the tail is distinctly wider. While the Tobago specimen has a spotted dewlap, it also displays a hemipenal bulge suggesting it is an adult male. Its stomach contained small wasps.

Del Rosario Castañeda and De Queiroz (2013) found Anolis tigrinus in a clade of nine species (A. lamari, A. menta, A. nasofrontalis, A. paravertebralis, A. pseudotigrinus, A. ruizii, A. solitarius, A. tigrinus, and A. umbrivagus). They share a small body size (40-60 mm adult male body size) large smooth head scales, a large interparietal scale bordered by large scales and usually in contact with the supraorbital semicircle scales, and smooth ventral scales that are larger than dorsal scales. Species in the tigrinus series are distributed at high elevations of the Sierra Nevada de Santa Marta (Colombia), the Andes of Colombia (Eastern Cordillera) and Venezuela, and the Atlantic forest of southeastern Brazil. They considered that the tigrinus series may be nested within the punctatus series representing a twig ecomorph subgroup of the punctatus series which also contains trunk-crown anoles. Del Rosario Castañeda and De Queiroz consider A. tigrinus and its relatives part of the punctatus series rather than a separate tigrinus series, but note that a clade containing A. tigrinus and all species closer to it than to A. punctatus could be recognized as a sub-series or a species group within the punctatus series.

The presence of Anolis tigrinus on Tobago supports the faunistic relationship between the Caribbean Plate island and the Coastal Ranges of Venezuela.

We collected tissue for molecular work and will soon know if it is identical to A. tigrinus or if it is a  relative. We also have evidence that Anolis tigrinus or something similar to it is present on Trinidad.

Literature cited

Del Rosario Castañeda, M., & De Queiroz, K. (2013). Phylogeny of the Dactyloa clade of Anolis lizards: new insights from combining morphological and molecular data. Bulletin of the Museum of Comparative Zoology, 160: 345-398.

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

Authors: Tom Anton, Renoir Auguste, Alvin Braswell, John C. Murphy, Mike G. Rutherford

Reasons to further explore the Trinidad & Tobago Herpetofauna

A satellite map of Venezuela and the surround area. The location

 of the Peninsula de Paria is indicated by the rectangle in the 

upper right hand corner. The insert shows a closeup of the 

peninsula and adjacent Trinidad (T). Three centers of endemism 

are labeled Cerro Humo (H), Cerro Patao (P) and Cerro Azul 

(A). The scale bar is 50-0 m. A Google Earth map. From 

Kaiser et al. 2015. 

The Peninsula de Paria in extreme northeastern Venezuela is an extension of a chain of high coastal mountains (elevations ~2800m) that span much of northern Venezuela and extends into the adjacent islands of Trinidad. The fauna of Tobago is also related to the Peninsula de Paria but from a different history. This region has been variously called the Cordillera de la Costa or the Coastal Range and the eastern continental extension has received minimal attention from herpetologists. Donoso-Barros (1965) reported survey results from Cerro Azul and described Mannophryne riveroi (Donoso-Barros, 1965a), the first endemic frog from the area, followed by Gonatodes ceciliae in 1966, the first endemic lizard - which is now also recognized from Trinidad. Stephen Edwards explored Cerro Azul and recognized a distinctive frog described many years later as Mannophryne venezuelensis by Manzanilla et al. (2007). Two centrolenid frogs, Celsiella vozmedianoi (Ayarzagüena & Señaris, 1997) and Vitreorana castroviejoi (Ayarzagüena & Señaris, 1997), were discovered on Cerro Humo. Rivas et al. (1999) described the microteiid Anadia pariaensis, Mijares-Urrutia et al. (2000) described the gymnophthalmid lizard Euspondylus monsfumus, and Barrio-Amorós et al. (2006) named Allobates caribe, all from the same area. Other herpetologists visited the Península de Paria and made important collections (e.g., Stefan Gorzula in 1978, Jose Ayarzagüena in 1996) but no additional species have been described from their material. With the completion of more extensive collections by several Venezuelan and international research teams, additional species and observations on poorly known species were recently published (e.g., Anadia pariaensis—Rivas et al. 2012; Strabomantis biporcatus—Barrio-Amorós & Kaiser 2008; Mannophryne riveroi—Barrio-Amorós et al. 2010a; Riama rhodogaster—Rivas et al. 2005; Taeniophallus nebularis Schargel et al. 2005).

In a recent paper Kaiser et al, (2015) reported on fieldwork in the cloud forest of Venezuela’s remote Península de Paria in 2001 resulted in the collection of several specimens that could unquestionably be classified as members of the genus Pristimantis. Subsequent analysis of comparative material in museum collections brought the total number of specimens to 44, and these collectively represent five new species. Two of these species, P. geminus and P. nubisilva have phenotypes remarkably similar to the Trinidadian P. urichi, supporting a prediction that Pristimantis from easternmost Venezuela may have given rise to Trinidadian forms. Pristimantis hoogmoedi is easily identified by its large size and red eyes. Two of the species, P. longicorpus and P. pariagnomus, are very distinct morphologically but are known only from the holotypes. The former is characterized by an elongate body form supported by relatively short limbs, whereas the latter has very distinctive hand morphology and is likely the smallest Venezuelan frog. All five species can be readily distinguished by their osteology, such as by the extent of the sphenethmoid and features on the roof of the mouth, as well as by the shape and rearrangement of mesopodial elements. The unexpectedly high diversity of Pristimantis in this region, along with high endemism of amphibians and reptiles in general, underscores the position of the Península de Paria as a center for frog biodiversity in Venezuela. The authors conclude that the similarity of these Paria species to Pristimantis from Trinidad, Tobago and the central Cordillera de la Costa represents a tangible piece of evidence for the close biogeographic link of the anuran fauna of these landmasses.

The Trinidad and Tobago herpetofauna is more diverse than previously thought. By previously I mean post-Kenny (1969-1979), post-Murphy (1997), post-Boos (2001). Each of those works were a snapshot of what we knew at the time but knowledge changes.

Species recently described or ones that have been resurrected from obscurity on Trinidad and Tobago are numerous, and include the following. Frogs: The Orinoco Basin Dendropsophus goughi (Boulenger) was formerly the widespread D. minuta. Scarthyla vigilans was recently reported from Trinidad by Smith et al. (2011). While it may have been a recent colonization, it is also possible it was simply over looked because it so closely resembles the widespread Scinax ruber.  Leptodactylus insularis was formerly L. bolivianus (Heyer and Heyer, 2013). Changes in lizards. The skink Mabuya falconensis is now Marisora aurulae Hedges & Conn, 2012, a species with a very small distribution on several islands and known from few specimens. And the skink, once thought to be the widespread Mabuya bistriata is now Copeoglossum aurae Hedges & Conn, 2012, with a very restricted distribution. The Trinidad zandolie which was once thought to be the widespread Ameiva ameiva is now the Caribbean Costal Range endemic Ameiva atrigularis (Ugueto et al. 2011). The once widespread Plica plica is now the Caribbean Costal Range endemic Plica caribeana (Murphy and Jowers, 2013). As for snakes the endemic Leptophis haileyi was added to the fauna of Tobago by Murphy et al. Dipsas variegata was added to the Trinidad fauna by Murphy and Rutherford (2014). Teddy Angarita-Sierra (2014) added the snake Ninia franciscoi, which has only been collected at Simla, in the Arima Valley, but may also be present in the Caribbean Coastal Range.

So if I made a list of the number of species that need name changes or descriptions (because they are undescribed) I am confident the list would contain twelve species. If I estimate the number of actual changes that are probably needed the number goes to at least twenty, about a quarter of the herpetofauna.

With these changes widespread species become less widespread, there are more endemic and near endemic species and the fauna becomes more specialized and more diverse. In short it becomes a more valuable resource in terms of culture, conservation, aesthetics, and science.

These changes don’t happen for free. They are funded by private and public money. If you are interested in supporting this research contact me at serpentresearch@gmail.com. We need funding for several projects.

References

Ayarzagüena, J. & C. Señaris (1996). Dos nuevas especies de Cochranella (Anura; Centrolenidae) para Venezuela. Publicaciones de la Asociación de Amigos de Doñana 8: 1–16.

Barrio-Amorós, C.L., G. Rivas & H. Kaiser (2006). New species of Colostethus (Anura, Dendrobatidae) from the Península de Paria, Venezuela. Journal of Herpetology 40: 371–377; http://dx.doi.org/10.1670/0022-1511(2006)40[371:NSOCAD]2.0.CO;2.

Barrio-Amorós, C.L. & H. Kaiser (2008). Distribution of Strabomantis biporcatus (Terrarana: Strabomantidae) in northern Venezuela, with comments on its phenotypic variation. Salamandra 44: 248–254.

Boos HEA. 2001. The Snakes of Trinidad and Tobago. College Station: Texas A&M University Press. 270 pp.

Donoso-Barros, R. (1965a). Nuevos reptiles y anfibios de Venezuela. Noticiario Mensual, Museo Nacional de Historia Natural, Santiago, Chile 102: 2–3.

Donoso-Barros, R. (1965b). A new dendrobatidae [sic] frog, Prostherapis riveroi from Venezuela. Caribbean Journal of Science 4: 485–489.

Donoso-Barros, R. (1966). Dos nuevos Gonatodes de Venezuela. Publicación Ocasional del Museo Nacional de Historia Natural, Santiago de Chile 11: 1–32.

Edwards, S.R. (1974). Taxonomic notes on South American dendrobatid frogs of the genus Colostethus. Occasional Papers of the Museum of Natural History, University of Kansas 30: 1–14.

Heyer, W. R., & Heyer, M. M. (2013). Systematics, distribution, and bibliography of the frog Leptodactylus insularum Barbour, 1906 (Amphibia: Leptodactylidae). Proceedings of the Biological Society of Washington, 126(3), 204-233.

Kaiser, H., C.L. Barrio-Amorós, G.A. Rivas, C. Steinlein & M. Schmid (2015). Five new species of Pristimantis (Anura: Strabomantidae) from the coastal cloud forest of the Península de Paria, Venezuela. Journal of Threatened Taxa 7(4): 7047–7088; http://dx.doi.org/10.11609/JoTT.o4197.7047-88.

Kenny JS.  1969. Amphibia of Trinidad. Studies on the Fauna of Curacao and Other Caribbean Islands 29(54):1–78.

Kenny JS.  1971. A further contribution on the Amphibia of Trinidad. Journal of the Trinidad Field Naturalist’s Club 1971:24–25.

Kenny JS. 1977. The Amphibia of Trinidad–an addendum. Studies on the Fauna of Curacao and Other Caribbean Islands 51:91–95.

Kenny JS. 1979b. Some recent colonizations. Journal of the Trinidad and Tobago Field Naturalist’s Club 1978–79:27.

Manzanilla, J., M.J. Jowers, E. La Marca & M. García-París (2007). Taxonomic reassessment of Mannophryne trinitatis (Anura: Dendrobatidae) with a description of a new species from Venezuela. Herpetological Journal 17(1): 13–42.

Mijares-Urrutia, A., J.C. Señaris & A. Arends (2000). Taxonomía de algunos microtéidos (Squamata) de Venezuela, I: Variación y distribución geográfica de Euspondylus del nordeste de Venezuela. Revista de Biología Tropical 48: 671–680.

Murphy, JC. 1997. The Amphibians and Reptiles of Trinidad & Tobago. Krieger Publishing Co. Malabar. 245 pp.

Murphy, J. C., & Jowers, M. J. 2013. Treerunners, cryptic lizards of the Plica plica group (Squamata, Sauria, Tropiduridae) of northern South America. ZooKeys, (355), 49.

Murphy, J. C., Charles, S. P., Lehtinen, R. M., & Koeller, K. L. (2013). A molecular and morphological characterization of Oliver’s parrot snake, Leptophis coeruleodorsus (Squamata: Serpentes: Colubridae) with the description of a new species from Tobago. Zootaxa, 3718(6), 561-574.

Murphy, J. C. and M Rutherford. 2014. The first report of the snail-eating snake Dipsas variegata (Duméril, Bibron and Duméril) on Trinidad, its relationship to Dipsas trinitatis Parker (Squamata, Dipsadidae), and a discussion of microcephalic and macrocephalic ecomorphs in Dipsas. Herpetology Notes, 7, 757-760.

Rivas F.G., E. La Marca & O. Oliveros (1999). Una nueva especie de Anadia (Reptilia: Sauria: Gymnophthalmidae) del noreste de Venezuela. Acta Biologica Venezuelica 19(4): 27–32.

Rivas, G.A., P.M. Sales Nunes, J.R. Dixon, W.E. Schargel, J.R. Caicedo, T.R. Barros, E.G. Camargo & C.L. Barrio-Amorós (2012). Taxonomy, hemipenial morphology, and natural history of two poorly known species of Anadia (Gymnophthalmidae) from northern South America. Journal of Herpetology 46(1): 33–40; http://dx.doi.org/10.1670/10-139.

Schargel, W.E., G. Rivas Fuenmayor & C.W. Myers (2005). An enigmatic new snake from cloud forest of the Península de Paria, Venezuela (Colubridae: Genus Taeniophallus ?). American Museum Novitates 3484: 1–24; http://dx.doi.org/10.1206/0003-0082(2005)484[0001:AENSFC]2.0.CO;2.

Smith, Joanna, J. Roger Downie, Rebecca F. Dye, Victoria Ogilvy, Daniel Thornham, Michael G. Rutherford, Stevland P. Charles, and John C. Murphy. "Amphibia: Anura: Hylidae Scarthyla vigilans (Solano 1971): Range Extension and New Country Record for Trinidad, WI With Notes on Tadpoles, Habitat, Behaviour and Biogeographical Significance." Check List 7, no. 5 (2011): 574-577.

Ugueto, G. N., & Harvey, M. B. (2011). Revision of Ameiva ameiva Linnaeus (Squamata: Teiidae) in Venezuela: recognition of four species and status of introduced populations in southern Florida, USA. Herpetological Monographs, 25(1), 113-170.

The Golden Treefrog: no longer an endemic to Trinidad

Phytotriades auratus. John C. Murphy

The critically endangered Phytotriades auratus (Boulenger, 1917) commonly known as the golden treefrog was thought to be an endemic species to Trinidad. This hylid grows to about 3.5 cm snout-vent length. In Trinidad, its distribution is restricted to the two highest peaks: El Tucuche (936 m) and El Cerro del Aripo (940 m). At these peaks, P. auratus is closely associated with the bromeliad Glomeropitcairnia erectiflora where it spends the majority of its known life cycle. However, a recent visit to Cerro Humo’s summit in eastern Venezuela brought about the discovery and first documentation of the species outside of Trinidad.

Rivas and de Freitas visited Cerro Humo, Venezuela in August 2014. While at the summit of Cerro Humo, they came across G. erectiflora on a fallen tree trunk along their path. Within the bromeliad, two P. auratus specimens were observed and photographed while a third was spotted on another bromeliad nearby (Rivas and de Freitas 2015). The significance of this find resulted in the range expansion and new country record for this critically endangered species. Given the geological history of Northern Trinidad and Venezuela, this find may not be considered surprising.

Perhaps the most significant aspect with the discovery of a population of P. auratus in Venezuela is that an additional population outside of Trinidad is potentially beneficial towards the conservation of the species. An estimation of the populations in Trinidad was first undertaken in 1995. Currently, an assessment of the Trinidad population is being updated using the eDNA (environmental DNA) method. This method involves collecting water samples from within the bromeliad and testing it for golden treefrog DNA. Based on the results, the number of golden treefrogs can be acquired and an estimate of population size can be deduced. An evaluation of the Venezuelan population is required and perhaps a similar approach can be used for the population in Cerro Humo. With potential threats to P. auratus’s conservation including climate change, habitat alteration, lack of legislative enforcement and the chytrid fungus, scientific research on the populations in both Trinidad and Venezuela is the first step towards reducing the threat status of the species.

Citation

Rivas, G. A. & de Freitas, M.  (2015)  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:  46;  153-157.

The disappearing Pauraque eggs

Martyn, Nigel, Sataish and I took on the task of searching for the proverbial needle in a haystack this morning.

That is, hoping that the ovenbird, after being caught in a net and having his feathers plucked would still be around.

Needless to say we did not see him – he wasn’t as dotish as we thought he was.

But something else had us baffled though. On the trek in, we saw a Pauraque (Nyctidromus albicollis) fly off leaving eggs on the forest floor. Martyn marked the spot with a stick so on our return trek we would be alerted before we approached the Pauraque.

However, on the return we saw the stick but not the eggs – they had mysteriously disappeared! Someone suggested the rastaman, and then the scrawny dog who was on the track. But there were no signs of either. There were no other suspects until Sataish jumped like a madman – nearly stepping on a Pseustes poecilonotus polylepis Dos Cocorite Snake (which was id’d by Carl Fitzjames later).

Ah well, Birding took a different turn this morning..! B R. Kamal