Thursday, November 15, 2018

Trinidad and Tobago's 7th annual Bioblitz goes to Toco in 2018


Bioblitz is a 24 hour event where scientists, naturalists and members of the public all come together to collect, identify and record as many species of fungi, plant and animal in a certain area. It is an opportunity for the public to see scientists at work and allows scientists to share their knowledge with others. It can also promote an area and showcase the biodiversity to be found there. 

This year will be the seventh edition and the chosen location is Toco to take place on 17-18 November. Toco is located in north east Trinidad and represents a portion of the island that has not been covered yet for the 24 hour event. It represents an area that covers a portion of the Northern Range forest as well as coastal ecosystems. The base camp will be the Toco Regional Complex. The main organizers for the Bioblitz are once again the Trinidad and Tobago Field Naturalists' Club in collaboration with The University of the West Indies Zoology Museum (UWIZM). This year as in past editions, it is sponsored by First Citizens. 

Given that there are proposed works to build a port in the area, these surveys offer a baseline of the biodiversity that are likely to be impacted by the work. What species of reptiles and amphibians are likely to be found in the area and how many? Perhaps something rare or new? Stay tuned to find out next week!

Sunday, November 11, 2018

Simla's Reptiles and Amphibians

Photo by Renoir Auguste

The William Beebe Research Station, also known as Simla is known by many scientists that have visited Trinidad. It is located in the Arima Valley and surrounded by tropical forests: ideal for researchers wanting to get a feel of the environment. However, over recent years the nearby quarry has altered the habitat. One wonders what kind of effect this may have on the wildlife, including the local herpetofauna?

Tantilla melanocephala. Photo by Rainer Deo


In October 2018 the Trinidad and Tobago Field Naturalists' Club's Herpetology Group, lead by current president undertook a trip to see what amphibian and reptile species they can find. Searches took place in the afternoon from 2:30 pm to 3:30 pm and then again at night from 6 pm to 9 pm. Within those 4 hours, the group collectively observed 17 herpetofauna species, including 3 snake species (Bothrops sp, Tantilla melanocephala, and Corallus ruschenbergerii), 6 lizard species (Hemidactylus mabouiaThecadactylus rapicauda, Gonatodes vittatus, G. ceciliae, Anolis planiceps, and Plica caribeana), and 8 amphibian species (Mannophryne trinitatis, Rhinella marina, Pristimantis urichi, Flectonotus fitzgeraldi, Boana xerophylla, Leptodactylus validus, Engystomops pustulosus, Phyllomedusa trinitatis).

Thecadactylus rapicauda. Photo by Rainer Deo


It was a bit surprising given the warm afternoon and relatively dry conditions at night to see that many species. Although most of these may be considered generalist type species, the habitat specialists (Pristimantis urichi and Flectonotus fitzgeraldi) were visually and audibly observed. This may suggest that the forest at and around Simla does offer suitable habitat for these species, for now. It would be interesting to regularly keep track of the diversity of herpetofauna at Simla.

Rhinella marina (background) and Pristimantis urichi (foreground) at Simla. Photo by Rainer Deo

Sunday, November 4, 2018

Lack of chytrid in Tobago's frogs

Chytridiomycosis has caused declines in multiple amphibian species across the world. The fungal infection has been detected in frogs in Tobago, specifically the endemic Aromobatidae stream frog Mannophryne olmonae (Alemu et al. 2008). However, there were no signs of clinical mortality.

A follow up study was conducted on six species of frogs (Leptodactylus validus, Engystomops pustulosus, Boana xerophylla, Pristimantis charlottevillensis, Hyalinobatrachium orientale tobagoense, and Mannophryne olmonae) from northeast Tobago in 2016 by Thomson et al. 2018 to assess the presence of the chytrid fungus. Based on their data of 176 samples, no chytrid was detected. According to the authors, their findings appear to indicate that the infection may have died out or is at very low levels. At least, for the species sampled and those in the northeast of the island.
Boana xerophylla from Tobago (Photo by: Renoir Auguste)

Alemu,J.B., Cazabon, M.N.E, Dempewolf, L., Hailey, A., Lehtinen, R.M., Mannette, R.P., Naranjit, K.T. and Roach, A.C.J. 2008. Presence of the chytrid fungus Batrachochytrium dendrobatidis in populations of the Critically Endangered frog Mannophryne olmonae in Tobago, West Indies. Ecohealth, 5:34-39.

Thomson, R., Hoskisson, P.A., Brozio, S., Downie, J.R. 2018. Apparent lack of chytrid infection in northeast Tobago's frogs. Living World, Journal of the Trinidad and Tobago Field Naturalists' Club, 2018: 82-86.

A new Anolis lizard discovered on Trinidad

There have been eight species of Anolis lizards reported for Trinidad and Tobago. Most of these have been introduced from elsewhere and it is uncertain as to exactly how these non-native Anoles came into the country. A recent report by Auguste et al. 2018 now adds a ninth: Anolis cristatellus (Dumeril and Bibron), the Puerto Rican Crested Anole. Given the recent spread of other introduced Anolis lizards to Trinidad, it will be important to keep track of the distribution of Anolis cristatellus as it has the potential to compete with and displace native Anolis species.


Anolis cristatellus (Photo by Kester Dass)
Auguste, RJ, Dass K, Baldeo, D. 2018. Discovery of the Puerto Rican Crested Anole, Anolis cristatellus Dumeril and Bibron, on Trinidad. Caribbean Herpetology 63: 1-2. DOI: 10.311611/ch63



Wednesday, October 3, 2018

Additional evidence for Phyllomedusa trinitatus being distinct from P. tarsius

Phyllomedusa trinitatis. JCM
The Tarsier Leaf Frog (family Phyllomedusidae), was described as Pithecopus tarsius by Cope in 1868. It is found in Brazil, Colombia, Ecuador, Peru, and Venezuela, and possibly Bolivia and Guyana. Its natural habitats are subtropical or tropical moist lowland forests, subtropical or tropical swamps, intermittent freshwater marshes, and heavily degraded former forest.

Mertens (1926) described Phyllomedusa trinitatis from Port of Spain, Trinidad and Phyllomedusa venusta was described by Duellman and Trueb (1967) from Darién Province, Panamá.

Barrio-Amorós (2009) doubted the distinctiveness of Phyllomedusa venusta from P. trinitatis, and also reidentified specimens identified as Phyllomedusa tarsius from along the Guyana border as P. trinitatis. This suggests  Phyllomedusa trinitatis likely extends into Guyana, and the records of Phyllomedusa tarsius from Guyana need re-examination.

A forthcoming paper by Mechkarska et al. (2018) examined peptidomic analysis of norepinephrine-stimulated skin secretions from the Trinidadian Leaf Frog and found 26 host-defense peptides. The primary structures of the peptides support the claim that P. trinitatis and P. tarsius are very closely related phylogenetically but are probably not conspecific as suggested by Duellman (1974).
Left: Phyllomedusa tarsius by Jean-Marc Hero. Right Phyllomeusa venusta
by Mauricio Rivera Correa



References

Barrio-Amorós CL. 2009. Distribución y aspectos de la historia natural de las ranas lémur (Hylidae: Phyllomedusinae) en Venezuela. Memoria de la Fundación La Salle de Ciencias Naturales. Caracas 171: 19–46.

Cope ED. 1868. An examination of the Reptilia and Batrachia obtained by the Orton Expedition to Equador and the Upper Amazon, with notes on other species. Proceedings of the Academy of Natural Sciences of Philadelphia 20:96–140.

Duellman WE. 1974. Taxonomic notes on Phyllomedusa (Anura: Hylidae) from the upper Amazon basin. Herpetologica  1:105-12.

Duellman WE, Trueb L. 1967. Two new species of tree frogs (genus Phyllomedusa) from Panamá. Copeia 1967:125–131.

Mechkarska M, Coquet L, Leprince J, Auguste RJ, Jouenne T, Mangoni ML, Conlon JM. 2018. Peptidomic analysis of the host-defense peptides in skin secretions of the Trinidadian leaf frog Phyllomedusa trinitatis (Phyllomedusidae). Comparative Biochemistry and Physiology Part D: Genomics and Proteomics. 2018 Dec 1;28:72-9.

Mertens R. 1926. Herpetologischen Mitteilungen VIII–XV. Senckenbergiana Biologica 8: 137–155.

Tadpoles of the Tobago Glass Frog

A metamorph of the Tobago Glass Frog.
The Tobago glass frog, Hyalinobatrachium orientale tobagoense is endemic to the island of Tobago. They reproduce by laying a clutch of gelatinous eggs on the underside of broad leaves overhanging streams, a mode of reproduction which is characteristic of all Hyalinobatrachium. The embryos develop on the leaf until hatching when they drop into the stream below where they develop further, eventually emerging as metamorphs.

Previous authors have reported on embryonic development, hatching, and tadpole growth and morphology in this frog. The tads initially lacking pigmentation, but with age develop pigment over much of the body, darker on the dorsal side, but lacking on the tail fins and ventral body. The tadpoles’ eyes are small and dorsally oriented.  They have very long tails, 64% of total length. In the lab, growth, is very slow. After six weeks, tadpoles had tripled in mass, increased in length by a little under 40%, but were still at Gosner stage 25, with no sign of limb buds. Previous authors have reported very slow growth and development in two glass frog species which took more than  200 days to reach metamorphosis.

Tadpoles hide in sediment and among rocks, gravel, and fallen leaves, and escape with bursts of fast swimming when disturbed. Given their secretive nature, it is not surprising that the behavior of these tadpoles is poorly known.

In a recent paper, Byrne et al. (2018) collected egg clutches of the Tobago Glass Frog and allowed them to hatch into tanks of native stream water.  Observations were made through a series of tests for substrate preference (gravel, rocks or leaves), shelter or open water preference, and surfacing behavior under different depths and turbulence levels. Tests found that tadpoles showed a preference for stream substrates over plastic tank floor, with the highest percentage of tadpoles found in gravel. Tadpoles preferred sheltered areas of the tank and surfaced significantly less when water was turbulent, with depth having no significant effect on surfacing behavior.

Byrne I, Judge C, Downie JR. 2018. The behaviour of recently hatched Tobago glass frog tadpoles. Herpetological Bulletin. 2018 Jun 1(144).

Tuesday, October 2, 2018

Brazilian Bent-toed Gecko, Gymnodactylus geckoides Spix


Bent-toed Gecko, Gymnodactylus geckoides is listed here on the basis of a single museum specimen. It is not likely part of the current fauna. If this genus is present on Trinidad, it can be identified by the presence of free fingers that are not expanded; the fingers have wide, undivided sub-digital lamellae; the distal phalanges are elevated above the basal ones; the nail or claw is placed between two scales with the ventral scale indented; straight, vertical pupils and dorsal scales are a mixture of granules and tubercles. This lizard is otherwise known from Brazil; its presence on Trinidad is problematic.
The only known specimen (FMNH 177679) of Gymnodactylus gekkoides supposedly collected in Trinidad's Arima Valley in 1962 by Edward Taylor. 

Anolis sagrei (Duméril and Bibron, 1837) Introduced

Anolis sagrei has apparently been introduced into Port-of-Spain, Trinidad
A Brown Anole, Anolis sagrei, photographed in southern Florida. JCM
Size. Males to 70 mm, females 48 mm; hatchlings 16 mm SVL. Smallest sexually mature male 35 mm, female 34 mm.

Identification. Brown to gray, with white or yellow patterning on the back. Dewlap orange or red with a white or yellow edge. Scales between the supraorbitals are variable ranging from none to several; scales separate the interparietal and supraorbital from the semicircles scales. Head scales keeled; five postrostrals; two postmentals. Mid dorsum has six rows of slightly enlarged scales; tail laterally compressed and may have a slight crest; keeled ventral scales that are pointed posteriorly.
Similar species. All Trinidad and Tobago anoles have cycloid (rounded) ventral scales with the exception of Anolis planiceps. Anolis sagrei has the subocular scales in contact with the upper labials. Anolis planiceps has the subocular scales and the upper labials separated by a row of scales. Anolis tigrinus has no enlarged mid-dorsal scales. Polychrus has femoral pores but all anoles lack them.

Distribution. This species has five currently recognized subspecies. Which one was introduced on Trinidad is unknown. The species is widespread in the Lesser Antilles and has been introduced into the USA (California, Florida, Texas, and Hawaii), Mexico, Belize, Aruba, and Taiwan. In Trinidad it is known only from the heart of Port of Spain, suggesting it may have arrived with ornamental plants.

Habitat. A ground dweller but will climb into low vegetation; this species thrives in almost all man-made habitats and they are abundant in suburban and urban environments.


Biology. Diurnal. Basks and forages on the ground and in vegetation. The diet includes insects, spiders, and other invertebrates (mites, isopods, gastropods). Females lay a single egg in moist soil or rotten wood at about 14-day intervals.

Guyana Dawn Blind Snake, Typhlophis squamosus Schlegel 1839


Typhlophis squamosus Schlegel 1839 in Error


Guyana Dawn Blind Snake, Typhlophis squamosus, has been reported in the literature as present in Trinidad. We have not been able to document its presence with a specimen. However, this has not stopped some authors from applying the common name “Trinidad Blind Snake” and even Wikipedia claims it is on Trinidad. We would like to see the evidence. Dorsal scales in 24 rows around mid-body, counted longitudinally the dorsals number 340−377; upper labials 4, lower labials 3; nostrils separated from the rostral by a single scale; tail ends in a sharply pointed scale. The dorsum and venter are dark brown, the head is pinkish cream, and the tail tip is brown. The known distribution is in Guyana and Brazil.

Red Whipsnake, Chironous scurrulus In Error

Red Whipsnake, Chironous scurrulus (Wagler). We have previously discussed this species and the evidence that suggests it is not part of the Trinidad fauna. Go to this post

Klauber's Threadsnake, Epictia tenella (Klauber, 1939)

Klauber's Threadsnake, Epictia tenella (Klauber, 1939)

Previously known as Leptotyphlops albifrons.

Size. 275 mm TL, tail very short about 6–7% of total length.

Identification. A small, silvery, striped snake with a yellow face and yellow tail; each scale row has a dark stripe. Head no wider than neck; rostral visible from above; nasals extend to border of mouth and separate two labials; no loreal; ocular scale contains a relatively large eye that nearly touches the anterior edge of the scale; two upper labials, the first upper labial contacts the supraocular; four lower labials; 219–229 ventrals; 15–20 subcaudals; 14 rows of smooth dorsal scales; tail ends in sharp spine; ventrals about as wide as dorsals.



Similar species. The supraocular and first labial in contact, and a pentagonal-shaped ocular scale separates it from all other Trinidad snakes.

Distribution. Epictia tenella occurs on Trinidad, Venezuela, and northern Brazil. Habitat. A fossorial snake found in urban gardens, savanna, and forest. It climbs on rock walls and tree trunks to reach food sources but is most often found under rocks, logs, and in leaf litter near ant and termite nests.
Biology. Active any time of day. This is an ant and termite specialists which locates colonies by following the chemical trails laid down by the social insects. This is the most frequently encountered species of Trinidad scolecophidian snakes.

Chacachacare Thread Snake, Epictia cf. fallax

Chacachacare Thread Snake
Epictia cf. fallax

Previously known as Leptotyphlops goudotii

Size. 160 mm in total length.

Identification. An Epictia that is extremely gracile, body shape (total length/diameter at mid-body) is 72.7 mm. The tail is 4.3% of the total length. The rostral scale extends between the eyes.

Similar Species.  Most easily confused with Klauber’s Threadsnake which has a body shape that is 51–62. and has a supraocular longer than frontal. The interoccipital scale s distinct from dorsals (it is not in E. tenella).  The body shape, combined with a tail that is 4.3% of the total length, and a rostral scale that extends between the eyes separate this snake from all other Epictia found in northern South America.

Distribution. Known only from Chacachacare Island.