Integrative revision of the giant pill-millipede genus Sphaeromimus from Madagascar, with the description of seven new species (Diplopoda, Sphaerotheriida, Arthrosphaeridae)

Abstract

The Malagasy giant pill-millipede genus Sphaeromimus de Saussure & Zehntner, 1902 is revised. Seven new species, S. titanus sp. n., S. vatovavy sp. n., S. lavasoa sp. n., S. andohahela sp. n., S. ivohibe sp. n., S. saintelucei sp. n., and S. andrahomana sp. n. were discovered, in one case with the help of sequence data, in the rainforests of southeastern Madagascar. The species are described using light- and scanning electron microscopy. A key to all 10 species of the genus is presented. All but one (S. andohahela) of the newly discovered species are microendemics each occurring in isolated forest fragments. The mitochondrial COI barcoding gene was amplified and sequenced for 18 Sphaeromimus specimens, and a dataset containing COI sequences of 28 specimens representing all Sphaeromimus species (except S. vatovavy) was analyzed. All species are genetically monophyletic. Interspecific uncorrected genetic distances were moderate (4–10%) to high (18–25%), whereas intraspecific variation is low (0–3.5%). Sequence data allowed the correct identification of three colour morphs of S. musicus, as well as the identity of a cave specimen, which although aberrant in its morphology and colouration, was genetically identical to the holotype of S. andrahoma.

Integrative description of two new species of Malagasy chirping giant pill-millipedes, genus Sphaeromimus (Diplopoda: Sphaerotheriida: Arthrosphaeridae)

“…nov. and the specimen from Vevembe, they cannot be assigned to the same species based on COI data alone until morphological characters of the male of the Vevembe population become available. Thus, S. inexpectatus and S. saintelucei show a genetic distance of only 4.1% in our analysis and 4.0% in the study conducted by Wesener et al (2014), and are regarded as separate species based on morphological characters. Nevertheless, the genetic distance of the COI sequence fragment in Sphaeromimus is usually 8-20% between two species .…”

“…The high genetic distances between the species of Sphaeromimus suggest an early speciation event, as previously suggested by Wesener et al (2010Wesener et al ( , 2014. The COI gene probably lost its resolution due to the accumulation of reverse substitutions over time.…”

“…Order Sphaerotheriida Brandt, 1833 Family Arthrosphaeridae Jeekel, 1974 Genus Sphaeromimus de Saussure & Zehntner, 1902 For a recent revision, see Wesener et al (2014).…”

“…11). In previous studies, the specimen from Vevembe was separated from S. ivohibe + S. musicus by a long branch and with weak support (see Wesener et al 2014). With a genetic distance of 6.3% between S. midongy sp.…”

“…It makes it possible to assign specimens of different stages, gender or with high morphological intraspecific variation to a species. Otherwise, it is not necessarily possible to assign such specimens to a species based solely on morphological evidence (see Wesener et al 2014). The COI barcode shows a close and well-supported relationship between S. midongy sp.…”