Integrative taxonomy of the new millipede genus Coxobolellus, gen. nov. (Diplopoda : Spirobolida : Pseudospirobolellidae), with descriptions of ten new species

Abstract

Pseudospirobolellidae is a poorly known family of spirobolidan millipedes with only two genera and five described species. Yet, the descriptive taxonomy and molecular systematics of this group have been largely neglected. Therefore, the present work presents an integrative taxonomic study of new pseudospirobolellid taxa in Thailand. To this end, two mitochondrial gene fragments (COI and 16S rRNA) combined with morphological characters were used to define the genus Coxobolellus, gen. nov. with 10 new species, viz. C. albiceps, sp. nov., C. compactogonus, sp. nov., C. fuscus, sp. nov., C. nodosus, sp. nov., C. serratus, sp. nov., C. simplex, sp. nov., C. tenebris, sp. nov., C. tigris, sp. nov., C. transversalis, sp. nov. and C. valvatus, sp. nov. The interspecific COI sequence divergences among the new species ranged from 6 to 15%. The intergeneric COI sequence divergence between species of Coxobolellus, gen. nov., Benoitolus birgitae and Pseudospirobolellus sp. ranged from 20 to 23%. Three major morphological differences separate Coxobolellus, gen. nov. from Benoitolus and Pseudospirobolellus, namely (1) the protruding process on the 3rd (and 4th) coxae on male legs, (2) the posterior gonopod telopodite divided into two parts, and (3) a conspicuous opening pore at the mesal margin at the end of the coxal part of the posterior gonopod. Thus, the new genus is well supported by both mtDNA and morphological evidence, while the delimitation of the 10 new species is supported by the congruence between mtDNA and morphological data. Yet, with respect to the relationships of Benoitolus birgitae, morphological data suggest a similarity with Coxobolellus, gen. nov. and Pseudospirobolellus, whereas mtDNA data place this species in the Pachybolidae. Further phylogenetic analyses are needed to explore this apparent incongruence and test the monophyly of Pseudospirobolellidae.

Combining mitochondrial DNA and morphological data to delineate four new millipede species and provisional assignment to the genus

“…Next to the morphological heterogeneity in Apeuthes, there is also a substantial amount of COI sequence variation and differentiation, with intraspecific COI divergences of 3-7% (mean: 5%), and interspecific COI divergences of 11-16% (mean: 13.7%). These figures are in line with those for the genus Coxobolellus (Pimvichai, Enghoff, Panha & Backeljau, 2020) of the related family Pseudospirobolellidae, which has intraspecific COI divergences of 0-5% (mean: 2%) and interspecific COI divergences of 6-15% (mean: 11%) (Pimvichai et al 2020). The corresponding values for the genera Atopochetus Attems, 1953 andLitostrophus Chamberlin, 1921 (family Pachybolidae) are also comparable, with intraspecific COI divergences of 0-8 and 0-1% (mean: 3 and 0%) respectively, and interspecific COI divergences of 9-17 and 9-11% (mean: 14 and 11%) respectively.…”

“…Total genomic DNA was extracted from dissected legs using the NucleoSpin Tissue kit (Macherey-Nagel, Düren, Germany) following the manufacturer's instructions. PCR amplifications and sequencing were done as described by Pimvichai et al (2020). Seven specimens were sequenced: Apeuthes maculatus (Attems, 1938) 1).…”

Figure 10 from: Srisonchai R, Sutcharit C, Likhitrakarn N (2021) The giant pill-millipede genus Zephronia Gray, 1832 from Thailand, with a redescription of Z. siamensis Hirst, 1907 and descriptions of three new species (Diplopoda, Sphaerotheriida, Zephroniidae). ZooKeys 1067: 19-56. https://doi.org/10.3897/zookeys.1067.72369

“…Recent intense collecting efforts made by Thai specialists in collaboration with the Department of National Parks, Wildlife and Plant Conservation across the country have revealed numerous interesting millipedes, especially in limestone areas. From these efforts, several new genera and numerous new species have been recorded and described (Pimvichai et al 2018(Pimvichai et al , 2020Srisonchai et al 2018a, b, c, d;Likhitrakarn et al 2020Likhitrakarn et al , 2021. The present contribution provides descriptions of three new species of the genus Zephronia, as well as a redescription of Z. siamensis Hirst, 1907 as based both on topotypes and near-topotypes.…”

Redescription of the giant Southeast Asian millipede Spirobolus macrurus Pocock, 1893 and its assignment to the new genus Macrurobolus gen. nov. (Diplopoda, Spirobolida, Pachybolidae)

“…Additional funding came from the Roy-Table 3. Estimates of COI mean sequence divergences within (on diagonal) and among (below diagonal) pachybolid and pseudospirobolellid genera (range in parentheses) (data based on Pimvichai et al 2018Pimvichai et al , 2020Pimvichai et al , 2022.…”