Cooper's Black Caecilian
Praslinia cooperi is a rare caecilian found on two Seychelles islands. Based on two individuals, P. cooperi has a total length of 166 mm (Exbrayat and Estabel 2006). Praslinia cooperi’s skull is flatter and contains more teeth than other known caecilians. The snout is rounded, faintly projects beyond the mouth, and is a length that is equivalent to the distance between the eye (Boulenger 1909). The ratio of the length to head-width, measured at the center of the eyes, is 33 mm in a juvenile specimen and approximately 34 mm in an adult specimen (Parker 1941). The rounded tentacle has a complete ring-like groove (Boulenger 1909) and is very close to the eye, sitting in the groove of the maxilla. The ratio of the distance from the tentacle to the eye and the distance of the tentacle to the nostril is 0.07 - 0.08 mm (Parker 1941). Praslinia cooperi has premaxillary teeth that are 1.6 - 1.8 mm in length. In adults, the maxillaries are 2.9 - 3.0 mm and in juveniles the maxillaries are 2.5 mm. The ectopterygoid is well developed. There are approximately 50 teeth per row expect for the inner mandibularis (Exbrayat and Estabel 2006). The body of P. cooperi is far longer than it is wide, a length of 20x the width, and has about 140 - 160 folds. The primary folds are 83 - 85 mm in length. The secondary folds are 69% - 85% of the length of the primary fold lengths. The cycloid scales are embedded in the skin of P. cooperi. The species does not have a rudimentary tail (Boulenger 1909).
Juveniles lack vernal teeth (San Mauro 2014).
Praslinia cooperi is the only member of the genus Praslinia (Werner 2000) and is distinguishable by tentacular apertures that are next to the eyes (Wilkinson et al. 2011). Praslinia cooperi differs from other caecilians in the following ways; it has is no temporal fossae in the dorsal view, the mesethmoid is not exposed, the teeth are uniform in size, there are secondary grooves and scales are present, there is no unsegmented terminal shield or terminal keel, there is no narial plugs, and there is no diastema between vomerine and palatine teeth (Exbrayat and Estabel 2006).
Praslinia cooperi’s body is a uniform blackish brown color. It is unclear if this description is from the species in life or preservative (Boulenger 1909).
Due to the rarity of this species, little is known about its individual variation.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Seychelles
Praslinia cooperi is found on Mahé and Silhouette Islands in the Seychelles. Praslinia cooperi is a specialist of the high forest and damper rainforests of the Seychelles archipelago. Praslinia cooperi has been found at an elevation of 280 m above the Indian Ocean (Stuart et al. 2008).
Life History, Abundance, Activity, and Special Behaviors
Praslinia cooperi is not common and is rarely found. It was last collected in 1991 and has neither been seen nor searched for since then (IUCN 2013).
Currently, very little is known about the morphology of P. cooperi larvae (San Mauro 2014), but they are assumed to have their ancestral reproductive mode of oviparity with free-living larvae (Nussbaum 1984, Nussbaum and Gerlach 2004, Parker 1941, Parker 1958). In the family Indotyphlidae, of which P. cooperi is a member, there is a significantly positive correlation between direct development and vernal teeth, with the loss of vernal teeth being a secondary trait. This correlation supports the hypothesis of a direct developing ancestor of Indian caecilians with vernal teeth and parental care with skin feeding. The lack of vernal teeth in juvenile P. cooperi indicates the species has free living larvae that do not feed on parental skin though further investigation is necessary (San Mauro 2014).
Trends and Threats
Praslinia cooperi is listed as “Endangered” because its estimated area of occurrence is only 44 km2. As of 2019, this species is considered rare and has not been seen since 1991. It is known to occur in two threat-defined locations in the Morne Seychellois National Park on Mahé Island and in the Silhouette National Park on Silhouette Island. Both of these national parks are not currently being managed and further habitat degradation threatens the populations. This lack of management is a justification for an "Endangered" status of P. cooperi (IUCN 2013).
Additionally, invasive species are also thought to affect population size. An invasive plant, Cinnamomum verum, that was originally introduced for commercial use, has become widespread and poses a sizable threat to P. cooperi by changing soil and leaf litter chemistry. Since most of the life of P. cooperi is spent underground this greatly affects its way of life. Further research is needed to quantify the tolerance of P. cooperi to C. verum specifically and other invasive plants (IUCN 2013).
Possible reasons for amphibian decline
General habitat alteration and loss
The species authority is: Boulenger, G. A. (1909). “A list of the freshwater fishes, batrachians and reptiles obtained by Mr. J. Stanley Gardiner’s expedition to the Indian Ocean.” Transactions of the Linnean Society of London. 2nd series, Zoology 12: 291–300.
Praslinia cooperi was found to be a member of the family Indotyphlidae based on a 400-bp region of the 12S rRNA and 900 bp of the 16S rRNA gene, making it the sister taxon to all other species within the Seychellean group of Caecilians, Grandisonia brevis, G. larvata, G. alternans, G. sechellensis, and members of the genus Hypogeophis (Hedges et al. 1993). San Mauro et al. (2014) rejected contradicting findings that there was a lack of divergences within the clade that Pyron and Wiens (2011) argued by implementing an approximately unbiased test.
The fossil record for most Seychellean Caecilians is limited and due to these gaps, the divergence within this group is determined from DNA sequence data of mitochondrial 12S and 16S rRNA because of the relatively high frequency of transitions relative to transversions. With that calibration, the divergence of Praslinia from the other Seychellean species is estimated to have occurred 25 mya, and the radiation of Hypogeophis and the species of Grandisonia began at 15 mya (Hedges et al. 1993).
Praslinia cooperi has a diploid number of 26 and one pair of microchromosomes. It is understood that among caecilians, species with a higher percentage of ancestral morphological character states tend to have more chromosomes and numerous microchromosomes compared to species that have a relatively derived morphology. Since P. cooperi has more microchromosomes it is assumed to have more derived morphology relative to other caecilians (Nussbaum and Ducey 1988).
Praslinia cooperi was named and first described by Boulenger in 1909. Praslinia cooperi was changed to Hypogeophis cooperi by Parker in 1942, but it was changed back to its original name based on previous phylogenetic analyses and inferences based on taxonomy (Exbrayat and Estabel 2006).
Seychelles caecilians, have probably been present at least since Seychellea (the Seychelles microcontinent) was last part of Gondwana (Maddock 2014).
Exbrayat, J.-M., Estabel, J. (2006). ''Anatomy with particular reference to the reproductive system.'' Reproductive Biology and Phylogeny of Gymnophiona (Caecilians), Vol 5. Exbrayat, J.-M., eds., Science Publishers, Enfield, NH, USA.
Gower, D. J., San Mauro, D., Giri, V., Bhatta, G., Govindappa, V., Kotharambath, R., Oommen, O. V., Fatih, F. A., Mackenzie-Dodds, J. A., Nussbaum, R. A., Biju, S. D., Shouche, Y. S., and Wilkinson, M. (2011). ''Molecular systematics of caeciliid caecilians (Amphibia: Gymnophiona) of the Western Ghats, India.'' Molecular Phylogenetics and Evolution, 59, 698-707.
Hedges, S. B., Nussbaum, R. A. and Maxson, L. R. (1993). ''Caecilian phylogeny and biogeography from mitochondrial DNA sequences of the 12S rRNA and 16S rRNA genes (Amphibia: Gymnophiona) .'' Herpetological Monographs, 7, 64-76.
Himstedt, Werner, 2000 ''Caecilian Ecology''. In Hofrichter, Robert. Amphibians: The World of Frogs, Toads, Salamanders and Newts. New York: Firefly. pp. 186–190
IUCN (2013). ''Praslinia cooperi''. The IUCN Red List of Threatened Species 2013. www.iucnredlist.org. Downloaded on 13 November 2018.
Nussbaum, R. A. (1984). ''Amphibians of the Seychelles.'' Biogeography and Ecology of the Seychelles Islands. D.R. Stoddart , eds., Dr. W. Junk Publishers, Boston, 379-415.
Parker, H.W. (1941). ''The caecilians of the Seychelles.'' Annals and Magazine of Natural History, Series II, 7, 1-17.
San Mauro, D., Gower, D.J. Müller, H., Loader, S.P., Zardoya, R., Nussbaum, R.A., Wilkinson, M. (2014). ''In Molecular Phylogenetics and Evolution.'' , 73, 177-189.
Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P., Young, B. (eds) (2008). Threatened Amphibians of the World. Lynx Edicions, IUCN, and Conservation International, Barcelona, Spain; Gland, Switzerland; and Arlington, Virginia, USA.
Taylor, E.H. (1968). The Caecilians of the World. A Taxonomic Review. University of Kansas Press, Lawrence, Kansas.
Written by Aileen Lavelle (AileenLavelle AT berkeley.edu), UC Berkeley
First submitted 2019-03-12
Edited by Ann T. Chang (2019-03-18)
Species Account Citation: AmphibiaWeb 2019 Praslinia cooperi: Cooper's Black Caecilian <http://amphibiaweb.org/species/1931> University of California, Berkeley, CA, USA. Accessed Mar 21, 2019.
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Citation: AmphibiaWeb. 2019. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 21 Mar 2019.
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