Calumma roaloko: A new species of Chameleon from Madagascar.

The island of Madagascar has long been seen as a biodiversity hotspot, with a high number of endemic species (species found nowhere else). However, studies over the past two decades have shown that this biodiversity has been considerably underestimated for many groups, as better biological surveying has revealed both a large number of cryptic species (species which resemble other species so closely that they cannot be told apart by simple physical examination) and species with limited ranges or secretive habits that had been overlooked by earlier surveys. Among Vertebrates this newly discovered biodiversity has been particularly notable in three groups, the Primates (Lemurs), Anurans (Frogs), and Squamates (Snakes and Lizards).

In a paper published in the journal Zoosystematics and Evolution on 19 October 2018, David Prötzel of the Zoologische Staatssammlung München, Shea Lambert of the Department of Ecology and Evolutionary Biology at the University of Arizona, Tucson, Ginah Tsiorisoa Andrianasolo of the Mention Zoologie et Biodiversité Animale at the Université d’Antananarivo, Carl Hutter of the Biodiversity Institute and Department of Ecology and Evolutionary Biology at the University of Kansas, Kerry Cobb of the Department of Biological Sciences at Auburn University, Mark Scherz, also of the Zoologische Staatssammlung München, and of the Zoologisches Institut at the Technische Universität Braunschweig, and Frank Glaw, again of the Zoologische Staatssammlung München, describe a new species of Chameleon from Madagascar.

Chameleons are an exclusively Old World group of Iguanid Lizards closely related to the Agamids (or Dragon Lizards) which are also found only in the Old World, the two groups together being referred to as the Acrodonta. They are noted for their ability to change colour, though this ability is not found in all species. Chameleons also have highly specialised feet, with five toes arranged into two opposing groups, to aid movement in trees (where most species are found), highly modified eyes, which can be pivoted seperately, and a sticky tongue that can be launched as a projectile at prey items (usually Insects), which are then drawn back into the mouth.

The new species is placed in the endemic Malagasy genus Calumma, and given the specific name roaloko, which means 'two colours' in Malagasy, in reference to the patterning of the males of the species, which have a bright green upper side and a white underside (females are a drab brown all over). The species is described from five specimens, an adult male and an adult female, plus two subadult males and a subadult female. The adult male is 93.7 mm in length, the female 85.5 mm. Both sexes have a soft appendage on their snout, with the males having an indigo stripe that runs from this through the eye to the back of the head.

In-life photos of four specimens of Calumma roaloko; (a) subadult male; (b) adult male; (c) subadult male; (d) adult female. Prötzel et al. (2018).

All of the specimens were collected at an altitude of 1100 m above sea level in a fragment of rainforest close to the Analamazaotra Special Reserve and Andasibe-Mantadia National Park, and within an area called the Réserve de Ressources Naturelles du Corridor Ankeniheny-Zahamena, one of a series of newly protected area of rainforest fragments, currently administered by several local councils, but which it is planned to add to the country's national parks system. The fragment of rainforest in which the Chameleons was found currently measures less than 300 km³ and is considered to be shrinking. Calumma roaloko could potentially be found in neighbouring forest fragments, including those within the longer standing Analamazaotra and Andasibe-Mantadia national parks, or the privately run  Réserve de Vohimana, all of which contain larger areas of forest. However, since the species has not yet been located outside its original forest fragment, Prötzel et al. suggest that it should be classified as Endangered under the terms of the International Union for the Conservation of Nature’s Red List of Threatened Species.

 Posed photos of a subadult male specimen of Calumma roaloko; (a) Indigo coloration on the rostral appendage and head scalation is apparent; (b) portrait of the same specimen.

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New Miniature Chameleons from Madagascar.

The Miniature Chameleons form a subgroup within the genus Brookesia (Leaf Chameleons), known as the Brokesia minima subgroup, after the first species discovered. These Chameleons tend to have extremely limited ranges, but are genetically quite distinct, implying the species diverged millions of years ago; this is quite surprising as the Malagasy climate has changed quite a lot during this time, which is not generally good news for species with limited ecological niches.

In a paper published in the journal PLoS One on 14 February 2012, a team led by Frank Glaw, of the Zoologische Staatssammlung München, carry out a review of the evolution and ecology of the Miniature Chameleons, and describe four new species within the group.

The first of these new species is Brookesia tristis, which reaches 24 mm in length and has lateral spines on the tail, a supranasal cone (horn above the nose), and a pelvic spine. B. tristis was found living in branches close to the ground (5-50 cm high) in a deciduous dry forest on a limestone mountain, the Montagne des Français. During the study a female was observed to lay two eggs, slightly under 6 mm in length, which hatched after 64 & 68 days, producing offspring 14 mm in length (more than half the adult length). The name tristris means doleful, or sorrowful, in reference to the threat of deforestation on Montagne des Français, despite its having recently been declared a nature reserve.

Male (A) and female (B) Brookesia tristis. From Glaw et al. (2012).

The second new species is Brookesia confidens, which reaches 23 mm, and lacks a supranasal cone, pelvic spines or lateral tail-spines. Found living on low branches (5-20 cm above the ground) in a deciduous dry forest in an area with numerous limestone outcrops, in the Ankarana National Park. The name confidens means confident, a reference to the good habitat protection in place in the Ankarana National Park. When alarmed B. confidens turns a dark colour, with a white stripe along its spine.

Male (A) and female (B) Brookesia confidens. From Glaw et al. (2012).

Brookesia micra measures under 20 mm in length, making it the smallest member of the group, and potentially (depending on how the measurements are taken) the smallest reptile and amniote (amniotes are tetrapod vertebrates that do not need to lay their eggs in water; reptiles birds and mammals, of which group the smallest members are small lizards). It has a short tail compared to other members of the group, which is an orange colour in adults. B. micra has a supranasal cone and a pelvic spine, but lacks lateral tail-spines. B. micra lives on the island of Nosy Hara off the north coast of Madagascar. The name micra means small.

Brookesia micra. (A) Adult male against a black ground in order to show the orange tail. (B) Juvenile on a finger tip. (C) Juvenile on a match-head. (E) Male in the wild. (F) Female in the wild. From Glaw et al. (2012).

Brookesia desperata is between 25 and 30 mm in length. It has three large tubercles on the side of the head, a supranasal cone, pelvic spines and well developed lateral tail spines. They were found living in the southern fringes of the Forêt d’Ambre Special Reserve, in branches 5-100 cm above the ground, and also living in banana plants where the forest had been cleared. A female was observed to lat two eggs. When alarmed the animals turn dark with a light line along the spine. The name desperata means desperate, a reference to the poor habitat protection in the Forêt d’Ambre Special Reserve.

Brookesia desperans. (A) Female with recently laid eggs; adult is showing stress colouration. (B) Close up showing (1) the pelvic spine and (2) the lateral tail spines. (G) Male. (H) Female. From Glaw et al. (2012).

The Miniature Chameleons are a curious group of animals. None of the known species are closely genetically related, suggesting the diverged millions of years ago. All species live in highly restricted habitats on an island we know to have undergone considerable climatic change in the last few million years. This would suggest that either the species are capable of surviving in a wider choice of habitats than they currently do, or that they have evolved to live in their current environments fairly recently. If the former is the case then an explanation as to why they currently inhabit such restricted ranges is needed. If the latter then it needs to be explained why none of the current species are closely related. We do not expect to see in nature a number of related species evolving to inhabit successive environments in parallel; rather some species should die out and others give rise to more than one daughter species - which would be closely related to one another.

Northern Madagascar, showing the distribution of six of the fifteen known species of Miniature Chameleons. From Glaw et al. (2012).

The Miniature Chameleons are also remarkable in their size; they are among the smallest amniotes, though some frogs and fish are smaller. The females lay very few, comparatively large eggs, no more than two in the smallest species. This suggests that it is the size of the egg, rather than the adult which is the limiting factor in amniote size; the eggs cannot get any smaller and remain viable, creating a restriction on how small the adults, who must lay the eggs, can get.

See also A living fossil eel discovered in Palau, New Mouse Lemur discovered in Madagascar and Reptiles on Sciency Thoughts YouTube.