Rhampholeon mboyae, sp.n. (Reptilia: Chamaeleonidae), a New Leaf Chameleon from Nguru Mts., Tanzania

Petr Nečas

Corresponding author: petr.necas@me.com 

Abstract

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Key words: Chameleons, Rhampholeon mboyae sp.n., taxonomy, life history, zoogeography, endemism, Nguru Mountains, Tanzania

Introduction

Development of Taxonomy of the African Leaf Chameleons of the Genus Rhampholeon

The taxonomy of African leaf chameleons, genus Rhampholeon, has undergone significant development over the years, driven by advances in morphological and molecular studies. This genus, which comprises small, cryptic chameleons primarily found in East Africa, has been the subject of extensive research due to its unique evolutionary history and ecological significance.

Rhampholeon spectrum was the first species described, recognized for its distinctive leaf-like appearance and small size (Buchholz, 1874). The initial classification of Rhampholeon species was based primarily on external morphological characteristics. Throughout the 20th century, the numberv of known species increased to 10. These studies laid the groundwork for recognizing the genus's complexity and the need for more refined taxonomic methods (Necas & Schmidt 2004); Tilbury 2018). The advent of molecular phylogenetics in the late 20th and early 21st centuries revolutionized the taxonomy of Rhampholeon. Matthee & al. (2004) conducted a comprehensive phylogenetic review of the genus, Mariaux & al. (2006): described 3 species from the Eastern Arc Range, Fisseha & al. (2013) reviewed the ''Rhampholeon uluguruensis complex, Branch& al.  (2014) described 4 new species from cloud forests of Mozambique, Hughes,& al. (2018) deciphered the cryptic diversity in Rhampholeon boulengeri and described 5 new cryptic species from central and west equatorial Africa and finally Menegon& al. (2022) unleashed the cryptic diversity in pygmy chameleons of the Eastern Arc Mountains of Tanzania and described 6 more species. The genus Rhampholeon has a scattered distribution over all equatorial Africa, with most species inhabiting small, isolated montane refugia. Despite some species developed very bizarre appearance with various spikes and cranial and nasal protrusions, most species are morphologically rather primitive. Many species can not be recognized unequivocally based on morphological features and only location and molecular analysis can confirm their belonging to a certain species. The Explosion of descriptions of new species and splitting of previously widespread species resulted into tripling the number of known species in the first quarter of 21th century to today's 30 known species.

Research has shown that vicariance and climate change played crucial roles in the speciation of Rhampholeon species. The fragmentation of forests due to climatic shifts and geological events, such as the rifting in East Africa, led to the isolation of populations and subsequent speciation. This process is evident in the distinct geographic distributions of Rhampholeon species, with many being confined to isolated montane forests (Menegon & al. 2022). The refined taxonomy of Rhampholeon has significant implications for conservation. Accurate species identification is essential for assessing the conservation status of these chameleons and implementing effective protection measures. Many Rhampholeon species are threatened by habitat loss and fragmentation, making it crucial to prioritise their conservation based on robust taxonomic knowledge (Hughes & al. 2018).

Fig 3,4: Dorsal and lateral view of the head of Chamaeleo ruspolii, BMNH London, Photo T. Mazuch

Discussion

Acknowledgements

Gratitude belongs to Joseph Mboya (Morogoro, Tanzania), a naturalist and nature conservationist, who discovered the population of Rhampholeon mboyae in the wild and documented it with photographs and field data. According to law, he did not disturb the wild animals in their biotope and did not kill and collect any voucher specimens.

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Nečas, P. (2025): Rhampholeon mboyae, sp.n. (Reptilia: Chamaeleonidae), a New Leaf Chameleon from Nguru Mts., Tanzania. Archaius 2(2): 1

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Killing Animals for the Purpose of Science

Peterson (2014) argues that type specimens are crucial for scientific documentation and taxonomy in ornithology, providing definitive references for species identification and allow for accurate comparisons with both known and new taxa. Peterson emphasizes that without type specimens, the integrity and precision of scientific classification and biodiversity studies would be compromised. There is hardly anything to object except for the fact that it is compromised anyway, ase some taxa have been described without type specimens, some types have been lost or preserved in a way that anyway does not enable their full usability for any methodologies, such as e.g. DNA analysis. 

Benefits and Limitations of Molecular Phylogeny 

Molecular phylogeny is nowadays heavily accentuated and considered almost a panacea. Indeed, it is extremely valuable and useful for analyzing evolutionary relationships, constructing phylogenetic trees, tracing lineage divergence, studying genetic variation, and identifying taxa. (Caetano-Anollés & Nasir 2012; Wang, 2022) However, it has also significant limitations, such as horizontal gene transfer, which blurs evolutionary relationships by introducing genes between unrelated species. Incomplete lineage sorting leads to mixed genetic signals from ancestral variations. Convergent evolution causes similar traits to evolve independently in different lineages, confusing phylogenetic analysis. Rapidly evolving lineages and hybridization events complicate accurate tree construction. Ancient divergences may weaken genetic signals, making it challenging to trace evolutionary history. Taxonomic misidentification and incongruence among different methods can lead to conflicting and erroneous conclusions. Overall, these constraints underscore the need for careful interpretation and multiple data sources in molecular phylogeny. (Sebiru, 2025; Steel & Penny, 2000)

The destructive influence of wrong conclusions based on molecular phylogeny are well known in herpetology: 

• The Case of the Green Iguana (Iguana iguana): Molecular phylogenetic studies initially suggested that the green iguana was closely related to the Lesser Antillean iguana (Iguana delicatissima). However, further morphological and ecological studies revealed significant differences, indicating that they are distinct species with different evolutionary histories (Wiens, 2008).

• The Confusion in the Genus Anolis: Molecular phylogenetic studies of the Anolis lizards initially grouped species based on genetic similarities. However, these groupings often conflicted with morphological and ecological data, leading to debates and revisions in the classification of Anolis species (Wiens, 2008).

Ich chameleonology, we have also examples where molecular phylogeny has led to incorrect conclusions about chameleons:

• The Case of the Panther Chameleon (Furcifer pardalis): Early molecular phylogenetic studies suggested that different color morphs of the panther chameleon represented distinct species. However, further research incorporating morphological and ecological data revealed that these color morphs are actually variations within a single species (Glaw et al., 2012).
• The Misclassification of the Leaf Chameleons (Rhampholeon): Molecular phylogenetic analyses initially grouped several species of leaf chameleons into a single genus, Rhampholeon. Subsequent studies using more comprehensive genetic data and morphological characteristics demonstrated that these species belong to multiple distinct genera, leading to a reclassification (Tilbury et al., 2004).
• The Confusion in the Genus Chamaeleo: Molecular phylogenetic studies of the genus Chamaeleo initially grouped species based on genetic similarities. However, these groupings often conflicted with morphological and ecological data, leading to debates and revisions in the classification of species within the genus Chamaeleo (Main et al., 2019).

The Constraints of Species Definition

From Linnaeus' morphological definitions to modern integrative approaches, the concept of species has evolved significantly, reflecting the complexity and diversity of life on Earth.

• Linnaean Species Concept: Carl Linnaeus (1707-1778): Proposed the biological classification system and the binomial nomenclature. Linnaeus defined species based on morphological characteristics and believed species were immutable and created by God (Stafleu, 1971).

• Biological Species Concept: Ernst Mayr (1942): Introduced the biological species concept, defining species as groups of interbreeding natural populations that are reproductively isolated from other such groups. This concept focuses on the ability to reproduce and produce fertile offspring (Mayr, 1942).

• Evolutionary Species Concept: George Gaylord Simpson (1951): Defined species based on their evolutionary lineage. An evolutionary species is a lineage evolving separately from others and having its own evolutionary role and tendencies (Simpson, 1951).

• Phylogenetic Species Concept: Willi Hennig (1966): Introduced the phylogenetic species concept, defining species as the smallest group of individuals that share a common ancestor and can be distinguished from other such groups by unique characteristics (Hennig, 1966).

• Ecological Species Concept: Leigh Van Valen (1976): Proposed the ecological species concept, defining species based on their ecological niche. Species are groups of organisms that occupy a distinct ecological zone (Van Valen, 1976).

• Genetic Species Concept: Alan R. Templeton (1989): Focuses on genetic distinctiveness, defining species as groups of populations that share a common gene pool and have significant genetic differences from other groups (Templeton, 1989).

• Integrative Species Concept: Current Approach combines multiple lines of evidence, including morphological, genetic, ecological, and behavioral data, to define species. This integrative approach acknowledges the complexity of species boundaries and the need for a holistic view (de Queiroz, 2007). 

This is an overview and the Integrative Species Concept in practice is a wish but not always the practice. There are the following constraints and tendencies, commented as ironical or paradoxical:

• The Paradox of Advancing Knowledge: The more we understand about evolution mechanisms, processes, and lineages, the less we can exactly define what a species is, leaving this question to the discretion of the author. As there is no common exact definition, it leads to controversial publications or discussions of subjective opinions (de Queiroz, 2007).

• The Paradox of Phylogeny Frenzy: Often, molecular phylogeny is preferred, accentuated, and considered dominant in interpreting evolutionary relationships. While this approach has benefits and limitations, the field of phylogeny has become a distinct scientific-philosophical stream. Consequently, many phylogenetic studies consider taxonomic implications "out of scope," ignoring the transfer of their results into taxonomy or avoiding it due to inadequate results or unfamiliarity with the ICZN (Almeida et al., 2023).

• Paradox of Failure of Efficient Regulation by ICZN: ICZN, as the organizational follower of Linnaeus, takes the liberty to modify approaches and define new rules, sometimes contradicting the founder's intentions. This paradox arises when new rules aim to make definitions and practices more precise but also allow regressions, such as permitting barbarisms in naming species, which are linguistically incorrect in Latin. Moreover, ICZN's rules are treated as ultimate, forcing scientists to comply, often reacting reluctantly to criticism and proposed changes (International Commission on Zoological Nomenclature, 1999).

• Paradox of Validation Role of Organizations: Organizations like IUCN and CITES, which have different scopes than science, play paradoxical roles in validating taxonomical acts. They rely on specialist groups and advisory organs to determine species validity for conservation and trade regulation purposes, effectively acting as arbiters in the global community and deciding the legitimacy of taxonomical acts (IUCN, 2025).

• Paradox of Regulation by Publishers and Periodicals. Scientific periodicals with high impact factors regulate publication acceptance based on subjective opinions of their advisory boards and referees. This can lead to the rejection of manuscripts for subjective reasons, obstructing and prolonging the publication process. It is possible for papers to be rejected simply because referees did not favor them, or to favor their publications on similar topics (Elsevier, 2025).

• Paradox of Impracticality and Disintegration of Science and Reality. Taxonomy and phylogeny may lose touch with the real world, ignoring the necessity of clarity and names for legislation, conservation, trade regulation, medicinal treatments, and practical field herpetology. While colorful and complex phylogenetic trees are valuable, they do not support practical applications, such as declaring a biospherical reserve or treating envenomation cases if species identification is unclear (Wiens, 2008).

Methodological and Terminological Inconsistencies

The comparison of morphological data with Menegon & al. (2022) is partly a bit problematic and can lead to inconsistencies. It is because their definition of morphological terms is confusing:   

• Original citation: "...species were measured using digital callipers to the nearest mm". They state they measured in mm but they give the dimensions in hundredths of millimetres, a precision, which is impossible in measuring the chameleon morphological features, especially soft tissues in fact.

• Original citation: "Snout-Vent Length (SVL) – tip of the snout to the anterior edge of the cloaca; Tail Length (TL) – tip of tail to posterior edge of the cloaca." The problem is, there is no "anterior and posterior edge of the cloaca". This definition is used in Batrachology, where the cloacal fissure e.g. in the genus Salamandra is longitudinal and has an anterior and posterior edge; not so in chameleons, where the cloacal fissure is situated transversally and defined as the meeting of the anterior and posterior cloacal lips. From the external morphological view, the only visible cloacal structure usable for measurement is the cloacal fissure, therefore, I assume, that they meant this structure and that actually, the measurements were done using this logic. If not, the sum of SVL and TL would not equal total length and relative tail lengths would be calculated wrongly, which seem not to be the case. 

• Original citation: "Head Length (HL) - from just behind the top of the casque to the tip of the snout" - as almost all Rhampholeon specimens possess a rostral protuberance, it is not clear, whether they measured it with it or without. Let us assume they meant actually "without rostral flap".

• Original citation: "Head Width (HW) – maximum width of head" - as the point, where the head might be the widest can lay before, between or behind the orbits, this parameter is very unpractical if not determined where it should be measured.

• Original citation: "Inter-orbital Distance (ID) – minimum width between orbits across crown" - as there is no common use of the term "crown" in chameleons and it has previously been used only by Branch & al. (2014) without any explanation, let us assume, an area demarcated rostrally by inter-orbital crest, dorsally by the top of the casque and laterally res. postero-laterally by the cranial lateral crests is meant. 

• Original citation: "Parietal Crest to Snout (PCS) – distance from the middle of parietal crest to the tip of the snout from a sagittal view." This is absolutely confusing term, as it is unclear how to define "the middle of parietal crest" and therefore, this measurement is of questionable value, even if the point of bifurcation of the parietal crest is meant in fact.

Adults of R. moyeri, R. uluguruensis and each of the new species were measured using digital callipers to the nearest mm: Snout-Vent Length (SVL) – tip of the snout to the anterior edge of the cloaca; Tail Length (TL) – tip of tail to posterior edge of the cloaca; Head Length (HL) - from just behind the tip of the casque to the tip of the snout; Head Width (HW) – maximum width of head; Orbit Diameter (OD) – maximum horizontal width of orbit; Inter-orbital Distance (ID) – minimum width between orbits across crown (Branch et al., 2014); Parietal Crest to Snout (PCS) – distance from the middle of parietal crest to the tip of the snout from a sagittal view. All measurements were taken on the right side of the specimen.

Morphological variation between the species was examined using a multivariate approach in SPSS v.21. Given the small number of individuals per species in the dataset (eight species, total n = 56), the analysis was not partitioned by sex. Using log transformed original vari- ables, a linear regression was run for each morphometric trait using a covariate (SVL) to remove the effect of body size. The resulting residuals were saved and input into a principal component analysis (PCA), to generate linear combinations of variables that explain overall morpho- logical variation. Sampling adequacy for the PCA was assessed using a Kaiser-Mayer-Olkin test, while commu- nalities were assessed to evaluate the contribution of each trait to the analysis (Tabachnick and Fidell, 1996). The varimax rotation of the component matrix was applied to maximize variation across multidimensional space. The first two principal components were extracted, and scores saved for each individual. Only the first PC had an eigen- value greater than 1 (see Results), so an analysis of vari- ance (ANOVA) was run for only PC1 with species as the fixed factor. Pairwise ad hoc Bonferroni tests were run for PC1 to examine pairs of species that differ for this PC.