Unknown chameleon discovered in Ivohiboro forest (Madagascar)

Unknown chameleon discovered in Ivohiboro forest (Madagascar)

by Alex Laube Verbreitung Science

There are still almost unexplored areas on Madagascar today. The Ivohiboro rainforest is located in the southeast of the island in the protected area of the same name, southwest of the southernmost foothills of the Andringitra Mountains. The forest itself is about 8.58 km² in size and thus only occupies a small part of the protected area. It is surrounded by savannahs and spans altitudes from 650 to 1460 m above sea level. The protected area is currently managed by local organisations and Madagascar’s Ministry of Environment. The last expedition to explore the Ivohiboro forest took place in 1924. Since 2016, researchers from the USA and Great Britain have now undertaken six expeditions to the small forest to study the biodiversity of plants, birds, mammals, reptiles, and amphibians there in more detail.

To detect reptiles and amphibians, the forest was divided into nine transects of about 200 x 20 m, each more than 200 m apart. The transects were searched for several days and nights. All animals found were documented and, if possible, identified down to genus or species level.

As a result, the scientists were able to identify 107 species of vertebrates and 219 plants. This enormous diversity of species underlines the importance of preserving the forest in terms of species conservation and indicates a well-functioning ecosystem. Among the species found were two chameleons: a Palleon species and a small Calumma. Unfortunately, the publication does not provide any further information on the former. The small Calumma had a conspicuous blue coloured rostral appendage, as it is found in Calumma linotum or Calumma boettgeri in the far north of Madagascar. As genetic studies are still lacking, it is unclear whether these chameleons are an extremely wide range extension – Ivohiboro lies about 1000 km south of the ranges of Calumma boettgeri and Calumma linotum – or whether it is perhaps even a new, as yet undescribed species.

A surprising haven: The biodiversity of an old-growth forest amidst a scorched landscape in Madagascar
Beatriz Otero Jimenez, Ren Montaño, Ryan S. Rothman, Rachel C. Williams, Patricia C. Wright
Conservation Science and Practice, 2023
DOI: 10.1111/csp2.12993

Chameleons at different altitudes of the Amber Mountain (Madagascar)

Chameleons at different altitudes of the Amber Mountain (Madagascar)

by Alex Laube Science

International scientists have intensively studied the different altitudes of the Amber Mountain and the amphibians and reptiles found there. The Amber Mountain (French Montagne d’Ambre) is a former volcanic massif in northern Madagascar. The mountain, which is up to 1475 m high, is mainly covered by rainforest, which belongs to the national park of the same name. To the north of the mountain is a dry forest that belongs to the Forêt d’Ambre Special Reserve. The north-western flank of the mountain has not yet been protected.

In the present work, amphibians and reptiles were observed and sampled over 12 km between 700 and 1470 metres altitude. The western slope of the Montagne d’Ambre at altitudes between 770 and 1290 m was also included in the study for the first time. In addition, animals were sampled in the Forêt d’Ambre from 470 m altitude. All animals found were measured. Cheek swabs, scales as well as live animals that had been euthanised were collected and genetically analysed. A total of 2631 observations of 34 species of amphibians and 48 species of reptiles were made. As expected, different animals occurred at different altitudes. The species richness of the Montagne d’Ambre was greatest at around 1000 m a.s.l. with 41 different species. Above 1100 m, about one third of the species found were locally endemic.

Two genetic clusters of the earth chameleon Brookesia tuberculata have been identified. Group 1 lives on the eastern flank of the Montagne d’Ambre at altitudes of 887 to 1170 m, group 2 at 1260 to 1455 m on the eastern flank and at 956 to 1150 m on the western slope of the Montagne d’Ambre. Group 1 showed a particularly high number of mitochondrial haplotypes, while group 2 had only one haplotype. The scientists assume that due to their small body size and high site fidelity, the species tends to form isolated groups rather than tree-inhabiting chameleons, which can overcome natural barriers more easily and thus move within a much larger environmental radius.

In Calumma linotum, the genetic differences between three groups at different altitudes were rather small. The measurement data of various body dimensions also showed no clear trend for this species at the different altitudes. Although Calumma linotum appeared to be slightly smaller at lower altitudes, this could have been due to subadult individuals misidentified as females. For Calumma amber and Calumma ambreense, body size decreased the higher the chameleons were found in the Montagne d’Ambre. This may be related to the cooler temperatures at higher altitudes, which contribute to slower growth. But it could also be that more younger animals were simply measured.

The study reveals interesting adaptations of different chameleon species to the altitudinal differences of the Montagne d’Ambre. It is possible that these are already the first indications of an early stage of speciation. The work also illustrates how important the different altitudinal levels are for species diversity.

Repeated divergence of amphibians and reptiles across an elevational gradient in northern Madagascar
Mark D. Scherz, Robin Schmidt, Jason L. Brown, Julian Glos, Ella Z. Lattenkamp, Zafimahery Rakotomalala, Andolalao Rakotoarison, Ricky T. Rakotonindrina, Onja Randriamalala, Achille P. Raselimanana, Safidy M. Rasolonjatovo, Fanomezana M. Ratsoavina, Jary H. Razafindraibe, Frank Glaw, Miguel Vences
Ecology and Evolution 13 (3)
DOI: 10.1002/ece3.9914

Keeping and breeding Calumma linotum

Keeping and breeding Calumma linotum

by Alex Laube Haltungsberichte

The keeping and breeding of small chameleons of the genus Calumma has so far, apparently, only found enthusiasts on a rather small scale. So it is all the nicer that a new report on the keeping and especially the successful breeding of Calumma linotum has just been published. Michael Nash from the USA has been keeping the species for over three years and gives a detailed account of his experiences.

He keeps his animals in the terrariums commonly used over here with a completely ventilated lid and either vents in the front bottom or the entire front as ventilation, living plants, and living substrate. T5 tubes with and without UV-B are used for lighting. For food he uses fruit flies (Drosophila spp.) to a good 50%, and otherwise among other things small crickets, house crickets, blowflies, and mantid nymphs.

The best breeding successes are achieved by keeping them individually and putting them together for a few days to mate during the imitation rainy season. To induce mating behaviour, dry and rainy seasons are imitated. The dry season is mainly characterised by a massive night-time drop in temperature to 10°C and less irrigation. During the imitated rainy season, temperatures rise to around 26°C during the day and 18-21°C at night, and there is also increased irrigation during the day.

The females lay 2-3 eggs after an average of 22 to 40 days of gestation. So far, it has been noticed that mated females of the species are capable of fertilisation for an unusually long time, namely up to five clutches. The eggs are first incubated at 16 to 21°C for two to four weeks. This is followed by a diapause of 30 to 45 days at 10 to 15°C. The eggs then lie in daytime conditions. Afterwards, the eggs lie at 22°C during the day and between 16.7 and 19.5°C at night. If the eggs do not show any embryonic and vascular development during shearing after the diapause, it is possible to imitate a second diapause – at the latest, after this, the first egg development should be visible. After 5 to 7 months, active young hatched under these incubation conditions. The author has successfully hatched eleven clutches so far.

All in all, a very readable husbandry report, which hopefully supports other keepers in breeding and long-term conservation of this interesting, small species in the terrarium.

Keeping and breeding Calumma linotum
Michael Nash
Responsible Herpetoculture Journal 7, 2023
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