Five new Rhampholeon species

Five new Rhampholeon species

by Alex Laube Neubeschreibungen Science

There is still a lot to discover about the small, brown pygmy chameleons on the African mainland. After new species were discovered in the Rhampholeon uluguruensis/moyeri complex in Tanzania two years ago, international scientists have now taken a closer look at the Rhampholeon boulengeri complex. And as expected, new species have been discovered!

The pygmy chameleons from this complex inhabit various habitats along the Albertine Rif). This 6000 km long chain of mountains and rifts stretches from Lake Albert in Uganda to Lake Tanganyika. It crosses the Democratic Republic of Congo, Rwanda, Burundi and Tanzania. In the genus Rhampholeon, the species hardly differ externally, but often live in very different habitats or can be easily distinguished from each other genetically. The authors analysed over 130 pygmy chameleons from more than 20 different locations as well as the lectotypes (the holotype no longer exists) of the species Rhampholeon boulengeri. Using genetic analyses, they were able to identify five new Rhampholeon species.

The already known species Rhampholeon boulengeri, described by Grauer in 1908, occurs exclusively in its type locality according to the current data. This is the Itombwe Plateau in the Democratic Republic of Congo, at altitudes between 2100 and 2470 metres.

Rhampholeon plumptrei was named in honour of the English zoologist Andrew Plumptre. As chairman of the Wildlife Conservation Society, he has been campaigning for species conservation along the African Rift Valley for almost 20 years. The species lives in montane and submontane rainforest at altitudes of 1203-2269 metres, although they are most commonly found at 1200 to 1700 metres. The distribution ranges from the east of the Democratic Republic of Congo with the Kahuzi-Biega National Park to the west of Kenya to the Kakamega Forest National Reserve. In between, Rhampoleon plumptrei can be found in Bwindi Impenetrable National Park, in Mabira and in Kalinzu Central Forest Reserve in western Uganda. It has a clearly visible nasal appendage and a slightly shorter tail than Rhampholeon boulengeri. Rhampholeon plumptrei grows up to 60 mm in size. The males have a white colouration on the throat and belly and one or two diagonal dark stripes on the body. Most chameleons of this species have a dark-coloured tubercle on the back of the neck.

Rhampholeon nalubaale was named after the Luganda word for ‘goddess’, which is also the native name of Lake Victoria, the largest lake in Africa. So far, only the females of this species are known, males have not yet been found. Rhampholeon nalubaale occurs in submontane rainforest at altitudes of 513 to 1506 metres. It is most common in the Kibale National Park in Uganda, but can also be found in the Budungo Central Forest Reserve in the same country and in the Kahuzi-Biega National Park and the Itombwe Natural Reserve in the Democratic Republic of Congo. Rhampholeon nalubaale grows up to 56 mm long. One of the animals found was illuminated with UV light and some of the tubercles in the face fluoresced blue, as is already known from other chameleons – but this is new for the genus Rhampholeon. The species occurs together with Trioceros johnstoni and Kinyongia tolleyae.

Rhampholeon bombayi was named after the waYao explorer Sidi Mubarak Bombay. He was born in 1820 on the border between Tanzania and Mozambique and was sold to India as a slave at an early age. He later returned to Africa and made a name for himself on expeditions by British explorers in East Africa. Rhampholeon bombayi grows up to 55 mm long. It lives in montane forests at altitudes of 1450 to 2330 metres in Rwanda and the Democratic Republic of Congo. It has so far been recorded in Kahuzi-Biega National Park, Kabobo Natural Reserve, Itombwe Natural Reserve and Nyungwe Forest National Park. Trioceros johnstoni and Trioceros schoutedeni also live in the same forest. The animals have two or three dark lines diagonally on the body, the tail and extremities are often darker brown than the trunk.

Rhampholeon msitugrabensis was named after the Albertine Rift. The Swahili word for forest, msitu, and the German word for rift, Graben, were combined. This ground chameleon grows up to 49 mm in size. It inhabits forest edges near Mpishi close to Kibira National Park in Burundi. Rhampholeon msitugrabensis is also described from Mount Bigugu in Nyungwe Forest National Park in Rwanda, so that its occurrence extends from 1986 to 2699 metres. In the Nyungwe Forest, Rhampholeon msitugrabensis occurs allopatrically with Rhampholeon bombayi, more precisely in the Kamiranzovu swamp area at 2000 to 2330 m altitude. Other chameleons that share a habitat with Rhampholeon msitugrabensis are Trioceros ellioti, Chamaeleo dilepis and Kinyongia rugegensis.

Rhampholeon monteslunae was named after its habitat, the Rwenzori Mountains on the border of the Democratic Republic of the Congo and Uganda. This mountain range, where the Nile rises, was described by Ptolemy as ‘Lunae Montes’ as early as 150 AD. Rhampholeon monteslunae occurs at altitudes of 1655 to 2360 metres and is most common in the Rwenzori Mountains National Park near the entrance to Nyakalengija. Another population can be found in the Bururi Forest Nature Reserve in Burundi. This ground chameleon grows up to 47 mm long. Kinyongia carpenteri, Kinyongia xenorhina, Kinyongia tolleyae, Trioceros ellioti, Trioceros johnstoni and Trioceros rudis are also found in the same forests.

Taxonomy of the Rhampholeon boulengeri Complex (Sauria: Chamaeleonidae): Five new species from central Africa’s Albertine Rift
Daniel F. Hughes, Mathias Behangana, Wilber Lukwago, Michele Menegon, J. Maximilian Dehling, Philipp Wagner, Colin R. Tilbury, Trisan South, Chifundera Kusamba, Eli Greenbaum
Zootaxa Vol. 5458 4, 2024, pp. 451-494
DOI: 10.11646/zootaxa.5458.4.1

Photo: From top left to bottom right Rhampholeon boulengeri, Rhampholeon plumptrei, Rhampholeon nalubaale, Rhampholeon bombayi, Rhampholeon msitugrabensis und Rhampholeon monteslunae from the mentioned publication

What influences colour patterns in chameleons

What influences colour patterns in chameleons

by Alex Laube Science

Chameleons are known for their ability to change colour. International scientists have now investigated what exactly influences different colour patterns in different populations. They want to know to what extent the habitat itself, the distance to other populations or social interactions influence the colour change.

The test subjects were European chameleons (Chamaeleo chamaeleon) caught in La Herradura and Sanlúcar in Spain. The two regions are around 230 kilometres apart. Other Chamaeleo chameleon were collected in the north-western Negev and on the Carmel coast in Israel (around 180 km apart). On the other hand, flap-necked chameleons (Chamaeleo dilepis) were captured in Simbithi, Zulu Falls and Maduma Boma in South Africa. The three locations are between 100 and 550 kilometres apart.

Each chameleon was subjected to two experiments. In the first, the scientists let the chameleon walk two metres on a horizontal stick, which was placed in the sun about one metre above the ground. In the second experiment, a second chameleon of the same species was placed on the same stick 50 cm away from the first. The colour patterns shown by the animal during the experiments and its behaviour were recorded for 20 minutes. The data was then analysed using computer programs. Blood was taken from a cut claw of all chameleons and genetically analysed. The habitats and soil conditions were also analysed in various ways and statistically evaluated. The captured animals were kept in ventilated plastic cages for a maximum of 12 hours and released after the analyses. Unfortunately, the study does not mention how many chameleons were caught and released in total.

As expected, it turned out that the individual populations of both the European and the flap-necked chameleon differed genetically from each other. The populations of Chamaeleo dilepis had significantly different haplotypes.

In the flap-necked chameleon, the females were significantly larger than the males in two locations, but not in Simbithi. The scientists also found that the colour patterns of the three populations studied could be clearly distinguished from each other. They concluded from the results that the colour patterns in Chamaeleo dilepis are primarily dependent on genetic isolation. The habitat itself and the size of the chameleons did not influence the colour patterns.

In the European chameleon, however, the situation was different: Body size and genetic distance to other populations predicted colour patterns in males very well. However, the colour patterns were independent of the location where the animals were found. Soil or vegetation colours only had a minor influence on the colour of females.

Genetic and behavioural factors affecting interpopulation colour pattern variation in two congeneric chameleon species
Tammy Keren-Rotem, Devon C. Main, Adi Barocas, David Donaire-Barroso, Michal Haddas-Sasson, Carles Vila, Tal Shaharabany, Lior Wolf, Krystal A. Tolley, Eli Geffen
Royal Society Open Science 11: 231554
DOI:  0.1098/rsos.231554

Genome of the panther chameleon decoded

Genome of the panther chameleon decoded

by Alex Laube Science

In recent decades, genetic research has developed rapidly. Since 2009, the so-called high fidelity (HiFi) Pacbio sequencing method has been available for sequencing genomes. Nevertheless, relatively little is being done in the reptile field. There are only about a hundred so-called reference genomes for reptiles, and none at all for chameleons. Scientists from China have now published a reference genome for the panther chameleon (Furcifer pardalis).

For the analysis, a 5-year-old male captive panther chameleon was killed using isoflurane and then dissected. Different tissues were frozen in liquid nitrogen. Skeletal muscle was used for short genome DNA sequencing and HI-C sequencing. Liver was used for HiFi sequencing. RNA from heart, liver, spleen, testis, lung, kidney, and skin were used for transcriptome sequencing.

The genome size of the panther chameleon from the K-mer analysis is 1.61 gigabase pairs (Gbp), containing only 22 so-called contigs, sets of overlapping DNA. The karyotype contains 11 chromosomes, each consisting of one to four contigs. Ten out of eleven chromosomes have repeat sequences (TAACCC). BUSCO analysis demonstrated a high completeness of the genome. The genome can be viewed in the NCBI BioProject under the number PRJNA974816 and in ScienceDataBank.

Efficient and highly continuous chromosome-level genome assembly of the first chameleon genome
Hongxin Xie, Zixuan Chen, Shuai Pang, Weiguo Du
Genome Biology and Evolution 131, 2023
DOI: 10.1093/gbe/evad131

 

Picture: Alex Laube

Karyotypes in chameleons

Karyotypes in chameleons

by Alex Laube Science

Scientists from Great Britain and Italy have now studied the chromosomes of different chameleon species. They examined the karyotype of a total of 83 different chameleon species. Among them were 57 Madagascan chameleon species, of which 32 karyotypes were described for the first time ever. For Calumma brevicorne, Calumma fallax, Calumma parsonii and Furcifer verrucosus, there were even several animals each available for examination. The scientists found out that presumably the fusion of chromosomes has reduced the total number of chromosomes in the course of evolution in chameleons. Presumably, it was mainly microchromosomes (particularly small chromosomes) that fused.

Microchromosome fusions underpin convergent evolution of chameleon karyotypes
Marcello Mezzasalma, Jeffrey W Streicher, Fabio M Guarino, Marc E H Jones, Simon P Loader, Gaetano Odierna, Natalie Cooper
Evolution, Juni 2023
DOI: 10.1093/evolut/qpad097

 

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

Genetics: Karyotype in the Veiled Chameleon

Genetics: Karyotype in the Veiled Chameleon

by Alex Laube Science

It has been known for some time that the sex of the Veiled chameleon (Chamaeleo calyptratus) is genetically determined. The species has an XX/XY system. Scientists from Russia, Great Britain, Italy, and Thailand have now studied the karyotype of the species, i.e. the characteristics of the chromosomes.

The probably most original karyotype of all chameleons is 2n= 36. This “primal chameleon” had six pairs of metacentric macrochromosomes and twelve pairs of microchromosomes, particularly small chromosomes. The Veiled chameleon, on the other hand, has a smaller number of chromosomes, namely only 2n=24. Using various genetic investigation methods, the researchers in the present study found that this karyotype probably arose through fusions. Microchromosomes apparently fused with each other twice, and micro- and macrochromosomes fused no less than four times. The latter, the so-called heterogeneous fusion between chromosomes of different sizes, is unusual for vertebrates. Normally, macro- and microchromosomes are located at different locations in the cell nucleus and are transcribed and replicated at different rates. However, this phenomenon is already known from alligators and turtles – for chameleons it is new.

Until now, it was also unclear which pair of chromosomes in the Veiled chameleon is actually responsible for the sex. In Chamaeleo chamaeleon, the second largest chromosome pair codes for sex. However, initial speculation suggests that in the Veiled chameleon the fifth chromosome pair (CCA5) may instead be the sex chromosome pair. The conjecture still needs to be validated by further research. It is also still up for discussion which gene is actually predominantly responsible for the development of the sex organs in the embryo – the researchers identified at least three possible genes on CCA5.

Identification of Iguania ancestral syntenic blocks and putative sex chromosomes in the Veiled Chameleon (Chamaeleo calyptratus, Chamaeleonidae, Iguania)
Katerina V. Tishakova, Dmitry Yu. Prokopov, Guzel I. Davletshina, Alexander V. Rumyantsev, Patricia C. M. O’Brien, Malcolm A. Ferguson-Smith, Massimo Giovannotti, Artem P. Lisachov, Vladimir A. Trifonov
International Journal of Molecular Sciences 23, December 2022
DOI: 10.3390/ijms232415838

Rhampholeon spectrum – not just one species?

Rhampholeon spectrum – not just one species?

by Alex Laube Science

The pygmy chameleon genus Rhampholeon is mainly found in East Africa. Rhampholeon viridis, Rhampholeon spinosus, and Rhampholeon temporalis each live in clearly defined and isolated areas of Tanzania. Rhampholeon spectrum, however, seems to be the complete opposite so far: The species has an enormous range in western Africa. It extends from Côte d’Ivoire through Ghana, Togo, and Benin to Nigeria and the outskirts of Niger and Chad, then on through Cameroon, Equatorial Guinea, and Gabon into the Central African Republic as well as the Democratic Republic of Congo and the Republic of Congo. Researchers from the USA and Cameroon have now investigated genetically what is behind the wide distribution.

Samples from an island at the northernmost tip of Equatorial Guinea, several mountains in Cameroon, and samples from two areas in Gabon were examined. To the researchers’ astonishment, it turned out that Rhampoleon spectrum is by no means genetically identical everywhere. Two clades could be identified from the samples: One in the lowlands and one in the montane forest, where the chameleons are found exclusively above 700 m a.s.l. A total of five genetically distinct populations were identified, several of which may represent new, as yet undescribed chameleon species.

The lowland clade includes the population in Gabon, where chameleons were sampled from Ivindo National Park and animals in an area near the town of Mekambo. The second population of the lowland clade occurs at low altitudes on Mount Korup, a mountain of volcanic origin. Mount Korup is located in the protected national park of the same name in Cameroon on the border with Nigeria.

The montane clade of the Rhampholeon spectrum includes three populations. One population occurs on Mount Biao on the island of Bioko, which belongs to Equatorial Guinea. A second population is found on Mount Cameroon, an active volcano in western Cameroon not far from the Gulf of Guinea. The type specimen of Rhampholeon spectrum comes from Mount Cameroon. The locality mentioned in the first description, Mapanja, is only a few kilometres away from one of the places where individuals were collected in the present study. This population is therefore probably the “true” Rhampholeon spectrum, the so-called topotypic group. The third population of the montane clade is found on three neighbouring mountains in Cameroon: Mount Kupe, Mount Mangengouba, and Mount Nlonako. Together with Mount Cameroon and Mount Biao, all three belong to the so-called Cameroon Line, a mountain range of volcanic origin that stretches along the border between Cameroon and Nigeria from the sea to Lake Chad.

The researchers are also looking into the question of how the different populations might have evolved. The separation between Rhampoleon spectrum and the pygmy chameleons in Tanzania can be dated to the late Eocene around 40 million years ago. During this time, the previously continuous rainforests in West, Central, and East Africa broke up into smaller, sometimes isolated fragments. The Rhampoleon spectrum clade then split into lowland and montane populations in the Miocene around 11.1 million years ago. In the Miocene, tectonic movements led to the uplift of a low mountain range that extended from southern Cameroon to the south of the Republic of Congo. Rivers, deserts, and other geographical barriers changed. Somewhat later, about 9.3 million years ago, the population on Bioko Island split off. The island’s pygmy chameleons are thus older than the island itself – the researchers explain this phenomenon by the fact that the island must have been connected to mainland Africa via a land bridge in the past. The chameleons would therefore have colonised the island, found a home on the mountain, and only then became isolated from the mainland. However, the genetically identical population on the mainland could not be found – researchers consider it extinct. In the late Miocene, around 6.9 million years ago, the populations on Mount Korup and in Gabon emerged. Only at the transition from the Miocene to the Pleistocene, 5.2 million years ago, did the populations on Mount Cameroon and Mount Kupe emerge.

Further research on this topic will show whether new species are actually hiding under the name Rhampholeon spectrum – chances are good. It would also be interesting to investigate populations of the species that are not mentioned in this study. Because, of course, the Rhampholeon spectrum from southern and eastern Cameroon, continental Equatorial Guinea, southern Gabon, and the Congo could also be further, independent populations. Science remains exciting!

Diversification and historical demography of Rhampholeon spectrum in West-Central Africa
Walter Paulin, Tapondjou Nkonmeneck, Kaitlin E. Allen, Paul M. Hime, Kristen N. Knipp, Marina M. Kameni, Arnaud M. Tchassem, LeGrand N. Gonwouo, Rafe M. Brown
PLOS One, December 2022
DOI: 10.1371/journal.pone.0277107

Hidden species within the genus Chamaeleo

Hidden species within the genus Chamaeleo

by Alex Laube Science

Thanks to genetic studies, the identification of species is much more precise today than it was a few decades ago. However, genetics always raises new questions. The genus Chamaeleo currently has 14 species. Scientists from South Africa have now investigated whether there might be other ‘hidden’ species of the genus Chamaeleo. At the same time, they investigated where the origin of the genus Chamaeleo might lie. For this purpose, the genetic material of all 14 species recognised so far was examined. Exciting results came to light: of the fourteen Chamaeleo species, thirteen were confirmed, but one was questioned. In addition, several new candidate species were identified.

The two different populations of Chamaeleo anchietae in western Angola and in south-eastern Congo and Tanzania probably represent two different species. If the animals from the Democratic Republic of Congo and Tanzania were true to be elevated to species status in the future, they would have to be named Chamaeleo vinckei according to taxonomy and a species description from 1950.

Chamaeleo gracilis seems to hide – which would not be surprising due to its wide distribution – at least three independent species. The “real” Chamaeleo gracilis would be found in Liberia, Sierra Leone and Guinea. The other two groups originate from the triangle of countries between Chad, Cameroon and the Central African Republic and from the border between Kenya and Tanzania. Unfortunately, only single specimens of Chamaeleo gracilis have been sampled, so no more far-reaching recommendation on the splitting of species can be made at this point.

The flap-necked chameleon (Chamaeleo dilepis), currently described as a single species, could contain a total of three species. One of the genetically distinct populations occurs in eastern Africa in Tanzania and Rwanda, while a second species is found in southern and eastern Africa, from South Africa through Botswana, Zambia, Namibia, Mozambique and Malawi to southern Tanzania. The third species would be distributed in west central Africa between Angola and the Congo. None of the candidate species matches the eight subspecies described so far purely on the basis of appearance. Therefore, a complete review of the previous subspecies, their status and the species status of the three newly emerged clades is necessary.

The results of the study on Chamaeleo necasi from Benin are also interesting. It turned out that the genetics identified the sampled animal as Chamaeleo gracilis. However, the specimen itself was not examined by the researchers. It could be a Chamaeleo gracilis misclassified by its appearance. In this case, the specimens used for the species description in 2007 would have to be viewed and sampled again in order to obtain more information about the actual species’ status.

In the course of the genetic investigations, the researchers found out that the origin of the genus Chamaeleo probably lies in South Africa. Chamaeleo namaquensis, the only terrestrial chameleon of the genus Chamaeleo, split off from the other Chamaeleo species as early as 40 million years ago in the Eocene. This makes the Namaqua chameleon from the Namib Desert and Damaraland the “oldest” chameleon of the genus Chamaeleo. Chamaeleo anchietae followed about 29 million years ago.

Out of southern Africa: origins and cryptic speciation in Chamaeleo, the most widespread chameleon genus
Devon C. Main, Bettine Jansen van Vuuren, Colin R. Tilbury & Krystal A. Tolley Conceptualisation
Molecular Phylogenetics and Evolution, Volume 175
DOI: 10.1016/j.ympev.2022.107578