Stable phylogenetic patterns in scutigeromorph centipedes (Myriapoda : Chilopoda : Scutigeromorpha): dating the diversification of an ancient lineage of terrestrial arthropods

Abstract

Although stable and well-supported relationships are in place for the three main clades (families) of Scutigeromorpha, the interrelationships of particular taxa within the most diverse family, Scutigeridae, are less clearly resolved. Novel molecular data for taxa from Mesoamerica, the Caribbean, southern Africa, New Guinea and previously unsampled parts of the Pacific are incorporated into phylogenetic analyses. Relationships across the tree are stable under variable analytical conditions, whether these are homology-based (multiple sequence alignment versus implied alignment; untrimmed versus trimmed datasets) or method-based (parsimony versus maximum likelihood). Hypervariable regions, contrary to common belief, add phylogenetic structure to the data, as measured by the increased support for many nodes when compared with the same alignments trimmed with Gblocks. Our analyses show that a Yule-3-rate model best explained the diversification of Scutigeromorpha during their 400 million years of history. More complete molecular data for the New Guinea genus Ballonema stabilise its position as sister group to Thereuoneminae. To reconcile scutigeromorph systematics with the phylogeny, the monotypic genus Madagassophora Verhoeff, 1936, is placed in synonymy with Scutigerina Silvestri, 1901 (n. syn.), its type species M. hova becoming Scutigerina hova (de Saussure & Zehntner, 1902) new comb. (from Scutigera), and Lassophora Verhoeff, 1905, is re-established for an Afro-Malagasy clade containing Lassophora nossibei (de Saussure & Zehntner, 1902) new comb. (from Scutigera) and a newly sequenced species from Mozambique that diverged at the base of the lineage to Thereuoneminae. The dated phylogeny of Scutigeromorpha is more consistent with ancient vicariant splits between Madagascar–southern Africa and Australia–New Caledonia than with younger dispersal scenarios, though some geologically young Pacific islands that harbour lineages dating to the Cretaceous demonstrate the potential for trans-oceanic dispersal.