New species of Treesnakes from the Comoras.

The Tree Snakes of the Comoros Islands have traditionally been clasified as being members of a single species, Lycodryas sanctijohannis, or the Saint John's Treesnake, despite considerable differences between the Snakes on different Islands.

In a paper published in the journal PLoS One on 24 August 2012, Oliver Hawlitschek of the Zoologische Staatssammlung Munchen, Zoltan Nagy of the Joint Experimental Molecular Unit at the Royal Belgian Institute of Natural Sciences, and Frank Glaw, also of the Zoologische Staatssammlung Munchen, redescribe the Treesnakes of the Comoros, coming to the conclusion that there are in fact two species of snakes in the islands, each of which should be subdivided into two subspecies, and none of which should be described as Lycodryas sanctijohannis.

The generic name Lycodryas is used for Treesnakes from the islands of the southwest Indian Ocean. The species sanctijohannis was descibed in 1879, based upon a specimen from Mayote Island, however Hawlitschek et al. discovered that a specimen in the British Museum of Natural History described in 1858 as Dipsadoboa maculata, and misidentified as coming from Central America, was in fact a Treesnake from Anjouan, and belonged to the same species as the specimen described as Lycodryas sanctijohannis. Under the complex and somewhat legalistic rules of Taxonomy, the earliest name given to a species is presumed to have precedence, even if the description is very poor. The Mayote Treesnake clearly does not belong in the genus Disadoboa, a group of New World Treesnakes only distantly related to the Snakes of the Comoros, but the specific name maculata is still the earliest name given to a Mayote Treesnake, so the correct name from these snakes should be Lycodryus maculata.

Hawlitschek et al. concluded that the Treesnakes of Mayote and Anjouan belonged to the same species, but were sufficiently different both genetically and morphologically to justify their placement in different subspecies. The Snakes of Anjouan are therefore described as Lycodryas maculata maculata, and the Snakes of Mayote as Lycodryas maculata comorensis. The Snakes of Grand Comoro and Moheli were judged to be sufficiently diffrent to be placed in a different species, named Lycodryus cococola, from Cocos (Coconut) and Cola (Inhabiting), making this the Coconut Treesnake (although the pun probably was intended). Snakes from Grand Comoro are described as Lycodryus cococola cococola and those from Moheli as Lycodrus cococola innocens, meaning inocent; the inhabitants of Moheli being particularly affraid of the snake, and prones to persecuting it, despite the snake being harmless and inoffensive.

Map showing this distribution of Treesnakes in the Comoros. Hawlitschek et al. (2012).

Treesnakes of the Comoros. (A) Male Lycodrus maculata maculata from Anjouan. (B) Female Lycodrus maculata maculata from Anjouan. (C) Male Lycodryus maculata comorens from Mayote. (D) Female Lycodryus maculata comorens from Mayote. (E) Male Lycodrus cococola innocens from Mohile. (F) Female Lycodrus cococola innocens from Mohile. (G) Male Lycodrus cococola cococola from Grand Comoro. (H) Female Lycodrus cococola cococola from Grand Comoro. Hawlitschek et al. (2012).

See also New species of Asian Coral Snake from western India, Velvet Geckos and Broad-headed Snakes; understanding the population structure of a favored prey item in order to help protect an endangered predator, Eruption on Mount Karthala and Reptiles on Sciency Thoughts YouTube.

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The Dwarf Pachyderms of Crete, Mammoths or Straight-Tusked Elephants?

Fossil Dwarf Elephants are known from a number of small islands around the world; this is not altogether surprising, dwarfism is common in populations of animals cut of on small islands (as is giantism). Animals in such environments often need to adapt to different niches to those they inhabit on larger land-masses, but are able to do so due to lack of competition, since there are few other animals present (conversely in environments with high biodiversity animals tend to be held in their own ecological niche by competition from other species, there is little possibility of switching to other niches, since these are already occupied).

In 1902 adventurer and fossil-hunter Dorothea Bates discovered a number of Elephant Teeth at Cape Malekas on Crete. At the time she assigned these to the genus Palaeoloxodon, Straight-Tusked Elephants, as P. creticus, the Cretan Dwarf Elephant, probably because Dwarf Straight-Tusked Elephants were already known from Sicily and Malta.

The location of Cape Malekas.

Recently this diagnosis has been challenged, and it has been suggested that the Cretan Dwarf Elephant is in fact a Mammoth. Two lines of evidence have been put forward to support this.

Firstly it was suggested that Crete became an island before the arrival of the genus Palaeoloxodon in Europe. However since this wad suggested earlier European members of the genus have been found and the precise date of the deposits in which the Cretan Elephant teeth were found has been questioned, suggesting that they could indeed have reached Crete while it was still attached to the mainland.

Then a genetic study was carried out by a team of scientists led by Nikos Poulakakis of the Natural History Museum of Crete and the Department of Biology at the University of Crete, which suggested that the Cretan teeth had in fact come from Mammoth. However the methodology used in this study was widely questioned, as was the possibility of recovering DNA from remains of this antiquity (about 800 000 years old).

In a paper published in the Proceedings of the Royal Society Series B, Biological Sciences on 9 May 2012, Victoria Herridge and Adrian Lister of the Palaeontology Department at the Natural History Museum in London, carry out a new study of the teeth originally collected by Bates, combined with new material from the same site, based strictly on the morphology of the teeth.

By carefully comparing the Cretan teeth to Palaeoloxodon and Mammoth teeth from the Pliocene and Pleistocene of Europe, as well as Dwarf Palaeoloxodon from Sicily and Malta, and Dwarf Mammoths from Sardinia. This suggested that the Cretan Elephants are in fact a form of Dwarf Mammoth, and should be referred to as Mammuthus creticus.

A pair of molars originally recovered from Cape Malekas by Dorothea Bates in the early twentieth century. Scale bar is 10 cm. Herridge & Lister (2012).

Herridge & Lister the compared the Cretan teeth with those of other known Dwarf Mammoths from around the world; M. lamarmorai from Sardinia, M. exilis from the Californian Channel Islands, and Dwarf forms of M. primigenius from Wrangel Island in Siberia and St Paul Island in Alaska. From this study they concluded that M. creticus was in fact the smallest of all known Mammoths, weighing about 31o kg on average, and standing 1.13 m at the shoulder. This makes it the second smallest Elephant of any sort, with only the Sicilian Dwarf Elephant, P. falconeri, being smaller, with an average weight of 240 kg and a height of 1 m at the shoulder.

See also What Nitrogen tells us about the diet of Mammoths, Did Spotted Hyenas colonize Britain once or twice? Elephant trackways from the United Arab Emirates, A new study of the Santorini eruption that destroyed ancient Minoa and Mammals on Sciency Thoughts YouTube.

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