Abstract
Species delimitation and species concepts have been a matter of debate among biodiversity researchers in the last decades, resulting in integrative taxonomy approaches and the use of modern species concepts, such as the phylogenetic, evolutionary or general lineage species concepts. The discussion of subspecies status and concepts has been addressed much less extensively, with some researchers completely refraining from recognizing subspecies. However, allopatric insular populations that are particularly differentiated have traditionally been assigned subspecies status. We studied the molecular phylogeny and morphology of endemic Comoran tree snakes of the genus Lycodryas. Taking an integrative taxonomic approach, we used the concept of independent lines of evidence to discriminate between evidence for specific and subspecific status. Molecular (mtDNA) and morphological data provided sufficient evidence to support four different taxa within Comoran Lycodryas. In a revision of this group, we propose two species, each with two subspecies. We present a discussion of the strong sexual dichromatism unique to Comoran Lycodryas within the genus and related genera that may be explained by sexual selection in combination with the absence of major predators. Then, we discuss the effects of insular evolution and the “island rule” on morphological traits in Comoran Lycodryas and in Liophidium mayottensis, another snake endemic to the Comoros. The absence of larger-bodied snakes may have promoted an increase in body size and the number of dorsal scale rows in these species. Finally, we discuss the subspecies concept, its applications and its significance for integrative taxonomy and for limiting taxonomic inflation. We emphasize that taxon descriptions should be based on an integrative approach using several lines of evidence, preferably in combination with statements on the underlying species concepts or operational criteria, to increase the objectivity and comparability of descriptions.
Highlights
Islands have been regarded as model systems for speciation even by the earliest evolutionary biologists [1,2]
Preliminary analyses with a smaller set of molecular markers presented the taxon Lycodryas gaimardii, which had not been included in previous studies, nested within Comoran Lycodryas
The multi-gene phylogeny presented in Fig. 1 shows L. gaimardii as a sister taxon to all Comoran Lycodryas
Summary
Islands have been regarded as model systems for speciation even by the earliest evolutionary biologists [1,2]. Comorensis’’ from Mayotte based on a juvenile specimen that is distinguished from Lycodryas gaimardii by a black line over its supralabials, below the eye to the corner of the mouth (often found in L. sanctijohannis), and dark crossbands that are narrower than in the typical form. It is possible that hatchlings (and juveniles) of L. sanctijohannis have distinct dark crossbands that become less distinct in adult specimens, similar to other Lycodryas species.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
