Whence Uroplatus and... there are how many leaf-tailed gecko species now?? (gekkotans part VII)

Time to press on once more with gekkotan lizards, and again with yet more on the remarkable leaf-tailed geckos (Uroplatus) of Madagascar. So far, we've been introduced to these lizards and have also looked at their anatomical pecularities and on a little bit of their history within the herpetological literature [image below shows U. phantasticus - I think - photographed at Mandatia; courtesy of Mary Blanchard].

But there's lots more to look at: at the recently named and soon-to-be-named species, at their phylogenetic position within Gekkota and, sadly, at their inevitable plight at human hands...

We'll begin with the affinities of these lizards. As mentioned in the previous gekkotan article, Garth Underwood* showed that Uroplatus should be included among the gekkonines. Specifically, Underwood (1954) favoured an affinity with the fan-fingered geckos (Ptyodactylus) of Africa and the Middle East. More recently, Kluge & Nussbaum (1995) found Uroplatus to be the sister-taxon of the African Urocotyledon species. An affinity with Ptyodactylus looks unlikely given that this taxon has been identified as part of a trans-Atlantic gekkotan clade (the recently named Phyllodactylidae) that almost certainly does not include Uroplatus (Gamble et al. 2008). Matoatoa from Madagascar and Afrogecko from, err, Africa have more recently been suggested to be the closest relatives of Uroplatus (Greenbaum et al. 2007) [adjacent image: how good is camouflage in Uroplatus? Here's an animal in the wild, photo by Mary Blanchard].

* I'm still gutted that I missed the ZSL's Underwood-themed meeting.

Raxworthy et al. (2008) found Paroedura to be the sister-taxon to Uroplatus, with Ebenavia and a Matoatoa + Blaesodactylus clade being successively more distant. These geckos are all animals of the western Indian Ocean and it seems that they represent a regional radiation; however, other Madagascan geckos (like the Phelsuma day geckos) don't seem to be part of this clade, so it still seems that the island's several gecko lineages colonised the region independently. Estimated divergence dates suggest the origin of Uroplatus in the Early Oligocene (Raxworthy et al. 2008), long after Madagascar had become isolated during the Cretaceous.

The discovery of U. giganteus and other new species

While most leaf-tailed geckos are somewhere round about 10-15 cm in total length, the group also includes some giants. The recently described U. giganteus can apparently reach 34.5 cm in total length (SVL: 20 cm at least), making it the third second largest gecko after the recently extinct Hoplodactylus delcourti of New Zealand (probably. I will discuss this species at length some time. SVL: 37 cm) and the surviving but endangered Rhacodactylus leachianus of New Caledonia (SVL: 24 cm). It's not a coincidence that the largest geckos are island endemics (Russell & Bauer 1991). Big geckos are also either rare or recently extinct, and are clearly highly vulnerable to habitat destruction and introduced predators.

U. giganteus [shown above; from Glaw et al. (2006)] was named in 2006, but had appeared in the pet trade prior to its official recognition: it even appeared on the cover of Reptiles magazine in 2001. By 2002 it had been determined that the new species originated from the Montagne d'Ambre region of northern Madagascar, and in 2004 Frank Glaw and colleagues were able to collect several specimens there (Glaw et al. 2006) [U. fimbriatus shown below; by Tim Vickers, from wikipedia].

A few other Uroplatus species have only been described quite recently: witness U. henkeli Böhme & Ibisch, 1990, U. malahelo Nussbaum & Raxworthy, 1994, U. malama Nussbaum & Raxworthy, 1994 and U. pietschmanni Böhle & Schönecker, 2003. U. guentheri Mcquard, 1908 has been said to be the rarest of leaf-tailed geckos and was known from just a single specimen (of unknown provenance) until a second one - collected in 1970 - was described in 1987 (Russell & Bauer 1987).

Many additional species are definitely waiting in the wings: Raxworthy et al. (2008) said that 20 species could be identified based on the samples they collected, and they referred to an 'in prep.' paper (by C. J. Raxworthy et al.) in which eight new species would be named and described. So far as I can tell, this work hasn't been published yet, but please announce it here if you know otherwise! One taxon long regarded as a subspecies of U. sikorae - U. s. sameiti - has already been argued to be worthy of recognition as a good species, U. sameiti (Pearson et al. 2007). U. sikorae itself was treated, erroneously, as a subspecies of U. fimbriatus for much of the 20th century [Greenbaum et al.'s (2007) Uroplatus phylogeny is shown below. A clade of small, short-tailed species - it includes U. ebenaui and U. phantasticus - includes several new taxa. Note that the large species (U. fimbriatus, U. giganteus, U. sikorae and U. henkeli) form a clade].

Glaw & Vences (2007) - in their wonderful, wonderful book (BUY IT like what I did) - also referred to certain of these new forms. They noted the presence of a small, U. henkeli-like form at Montagne de Français and Ankarana that awaits evaluation, and said that both U. sikorae and U. henkeli are "in need of taxonomic revision and probably [contain] numerous new, undescribed species" (Glaw & Vences 2007, p. 374). U. ebenaui is definitely a complex of several species and still needs sorting out (Glaw & Vences 2007, p. 378) and its different populations did not group together in Greenbaum et al.'s (2007) cladistic analysis: most were closer to U. phantasticus than to 'true' U. ebenaui. U. phantasticus itself might be "a composite of several species" (Glaw & Vences 2007, p. 378) and definitely occurs in distinct small and large forms. A population of U. giganteus-like animals from Marojejy might represent a distinct taxon: they formed the sister-group to U. giganteus proper in one study and were identified therein as U. cf. giganteus (Greenbaum et al. 2007) [image below shows the same U. phantasticus specimen from Mandatia featured at the very top (photo by Mary Blanchard, used with permission). It looks like U. phantasticus, but I didn't know they came in this purplish colour. Is it something new?].

Clearly, there is still much to learn about these remarkable, attractive lizards. As expected for species that are endemic to restricted, forested regions of Madagascar, leaf-tailed geckos are seriously threatened by the extensive deforestation that is occurring across the island (some of it for the purpose of coffee growing). U. malahelo - discovered in 1992 in the Malahelo Forest, Ambatorongorongo - is only known from an isolated patch of rainforest that was being burned and cut down when the species was discovered (Nussbaum & Raxworthy 1994), and its describers estimated that its habitat was unlikely to survive intact for more than another three years*. The species may now be extinct, but might occur at other locations and await discovery there. While leaf-tailed geckos are CITES-listed (since 2004, all species have been on appendix 2), they've been - and continue to be - extensively collected for the pet trade, and there are good reasons for thinking that this is putting severe pressure on their populations. Please read this article on Global Geckos for more.

* Ramanamanjato et al. (2002) brought attention to the rich fauna and high conservation priority of the region.

UPDATE: for more on new/yet-to-be-named Uroplatus species, check out the discussion thread here at Geckos Unlimited. The photo below was shared there: the animal resembles U. sikorae somewhat but differs in some respects (it doesn't seem to have fringes on its limbs, for example) and might be new.

Next: flying geckos!

For previous Tet Zoo articles on gekkotans see...

• The Tet Zoo guide to Gekkota, part I
• Gekkota part II: loud voices, hard eggshells and giant calcium-filled neck pouches
• Squirting sticky fluid, having a sensitive knob, etc. (gekkotans part III)
• Lamellae, scansor pads, setae and adhesion... and the secondary loss of all of these things (gekkotans part IV)
• The incredible leaf-tailed geckos (gekkotans part V)
• 300 years of gecko literature, and the 'Salamandre aquatique' (gekkotans part VI)

For previous Tet Zoo articles on neat squamates see...

• Mosasaurs might have used the same microscopic streamlining tricks as sharks and dolphins
• Tongues, venom glands, and the changing face of Goronyosaurus
• Dinosaurs come out to play (so do turtles, and crocodilians, and Komodo dragons)
• Tell me something new about basilisks, puh-lease
• 'Cryptic intermediates' and the evolution of chameleons
• The Great Goswell Copse Zootoca
• Of giant plated lizards and rough-necked monitors
• Ermentrude the liolaemine
• Evolutionary intermediates among the girdled lizards
• Hell yes: Komodo dragons!!!
• Amazing social life of the Green iguana
• Arboreal alligator lizards - yes, really
• Pompey and Steepo, the world-record-holding champion slow-worms

Refs - -

Gamble, T., Bauer, A. M., Greenbaum, E. & Jackman, T. R. 2008. Out of the blue: a novel, trans-Atlantic clade of geckos (Gekkota, Squamata). Zoologica Scripta 37, 355-366.

Glaw, F., Kosuch, J., Henkel, F.-W., Sound, P., & Böhme, W. (2006). Genetic and morphological variation of the leaf-tailed gecko Uroplatus fimbriatus from Madagascar, with description of a new giant species. Salamandra, 42 (2/3), 129-144

- . & Vences, M. 2007. A Field Guide to the Amphibians and Reptiles of Madagascar. Vences & Glaw Verlags (Cologne).

Greenbaum, E., Bauer, A. M., Jackman, T. R., Vences, M. & Glaw, F. 2007. A phylogeny of the enigmatic Madagascan geckos of the genus Uroplatus (Squamata: Gekkonidae). Zootaxa 1493, 41-51.

Kluge, A. G. & Nussbaum, R. A. 1995. A review of African-Madagascan gekkonid lizard phylogeny and biogeography (Squamata). Miscellaneous Publications, Museum of Zoology, University of Michigan 183, 1-20.

Nussbaum, R. A. & Raxworthy, C. J. 1994. A new species of Uroplatus Duméril (Reptilia: Squamata: Gekkonidae) from southern Madagascar. Herpetologica 50, 319-325.

Pearson, R. G., Raxworthy, C. J., Nakamura, M. & Peterson, A. T. 2007. Predicting species distribution from small numbers of occurrence records: a test case using cryptic geckos in Madagascar. Journal of Biogeography 34, 102-117.

Ramanamanjato, J.-B., Mcintyre, P.B. & Nussbaum R. A. 2002. Reptile, amphibian, and lemur diversity of the Malahelo Forest, a biogeographical transition zone in southeastern Madagascar. Biodiversity and Conservation 11, 1791-1807.

Raxworthy, C. J., Pearson, R. G., Zimkus, B. M., Reddy, S., Deo, A. J., Nussbaum, R. A. & Ingram, C. M. 2008. Continental speciation in the tropics: contrasting biogeographic patterns of divergence in the Uroplatus leaf-tailed gecko radiation of Madagascar. Journal of Zoology 275, 423-440.

Russell, A. P. & Bauer, A. M. 1987. Rediscovery of Uroplatus guentheri (Reptilia: Gekkonidae). Bulletin du Muséum National d'Histoire Naturelle 4C Serie 9 Sect. A. No 4, 961-966.

- . & Bauer, A. M. 1991. The giant gecko Hoplodactylus delcourti and its relations to gigantism and insular endemism in the Gekkonidae. Bulletin of the Chicago Herpetological Society 26, 26-30.

Underwood, G. 1954. On the classification and evolution of geckos. Proceedings of the Zoological Society of London 124, 469-492.