Is Millipede Taxonomy Based on Gonopod Morphology Too Inclusive? Observations on Genetic Variation and Cryptic Speciation inBicoxidens flavicollis(Diplopoda: Spirostreptida: Spirostreptidae)

Abstract

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Sechelleptus arborivagus sp. nov., a new arboreal spirostreptid millipede (Diplopoda, Spirostreptidae) endemic to Mayotte Island (Comoros Archipelago), Indian Ocean

“…Although our relatively small taxon sampling, the phylogenetic analysis strongly recovers Sechelleptus as monophyletic and discriminates at least two or three different groups. Furthermore, the mean inter-specific distance values (14.9% for COI and 5.1% for 16S) were remarkably similar to previous studies that reported the presence of high genetic divergence among population of different spirostreptid species (Mwabvu et al 2013(Mwabvu et al , 2015, suggesting the existence of more than one species in those taxa. It is argued that high level of divergence between identified spirostreptid species may indicate that changes in genital morphology occur rather slowly relative to the high rate of substitution in mitochondrial sequences (especially for COI), and may underestimate species diversity.…”

“…The relationships among the outgroups were not the primary focus of the present study, but are consistent with previous studies (Mwabvu et al 2013(Mwabvu et al , 2015Tinago et al 2017) that showed paraphyletic groups suggesting the presence of cryptic species (i.e., Bicoxidens spp.) and possible identification errors in the GenBank database.…”

“…Millipede systematics is mainly based on male gonopods because they use to be species-specific (Bond et al 2003). However, studies based on DNA have demonstrated that molecular divergence in different millipede groups may not reflect divergence in morphology-based identifications and may hide considerable variation (Bond & Sierwald 2002;Bond et al 2003;Adams et al 2009;Mwabvu et al 2013Mwabvu et al , 2015Tinago et al 2017). Although our relatively small taxon sampling, the phylogenetic analysis strongly recovers Sechelleptus as monophyletic and discriminates at least two or three different groups.…”

Deciphering phylogenetic relationships and delimiting species boundaries using a Bayesian coalescent approach in protists: A case study of the ciliate genus Spirostomum (Ciliophora, Heterotrichea)

“…The intra-specific genetic divergences in S. teres reach up to 20.81%, a value above that of Carchesium but distinctly below the 26% threshold in some arthropods 59 . Interestingly, about 19% sequence divergences were observed between two morphologically indistinguishable populations of the millipede Bicoxidens flavicollis 60 . Nonetheless, the present statistical tree topology tests (Supplementary Table S21) and delimitation analyses (Table 1) suggest that at least the population Mdg3 of the S. teres morphospecies might represent a distinct taxon.…”

Análise cladística e revisão taxonômica de Pseudonannolene Silvestri, 1895 (Spirostreptida, Cambalidea, Pseudonannolenidae)

“…Machos possuem o primeiro par de pernas modificado, pênis na coxa do segundo par de pernas e gonópodos (oitavo ou nono par de pernas modificados) para função sexual (Silvestri 1903;Blower 1985;Koch 2015). A identificação de espécies é feita através da morfologia do gonópodo (Hoffman 1980;Jeekel 1985;Mwabvu et al 2013;Enghoff et al 2015). A partir de diferenças relacionadas ao gnatoquilário (originado a partir da primeira maxila) e do gonópodo a ordem é dividida entre as subordens Spirostreptidea e Cambalidea.…”