Integrative systematic revision of a Mediterranean earthworm family: Hormogastridae (Annelida, Oligochaeta)

Abstract

The problem of reconciling earthworm taxonomy and phylogeny has shown advances with the application of molecular techniques, yet they have proven insufficient. Integrative systematics could solve this by combining multiple sources of evolutionary information. Relatively low diversity, restricted range and low nomenclatural conflict make Hormogastridae Michaelsen, 1900 a desirable target for an integrative systematics approach. The main systematic conflicts within this family are the polyphyly of the species Hormogaster pretiosa Michaelsen, 1899, the widespread presence of cryptic lineages, the lack of resolution of supraspecific relationships and the paraphyly of the genus Hormogaster Rosa, 1877 (found to be composed of four well-supported genus-level clades by molecular phylogenetic inference). This work integrates all the existing information by performing phylogenetic inference based on morphological, molecular and total evidence datasets, comparing their performance with the topology obtained by phylogenomic analyses. It also includes a comparative study of representatives of the main clades based on microcomputed tomography (µCT) reconstructions. The addition of morphological characters improved the resolution of the Hormogastridae tree; ancestral state reconstruction displayed the evolution of character states and provided morphological diagnoses for the genera within a new system, which incorporates information about ecological niches and biogeography.

French Mediterranean islands as a refuge of relic earthworm species: Cataladrilus porquerollensis sp. nov. and Scherotheca portcrosana sp. nov. (Crassiclitellata, Lumbricidae)

“…Whatever explicative hypothesis is retained, these disjunct distributions, as previously observed in other earthworm genera (pérez Losada et al 2011;Domínguez et al 2018;Marchán et al 2018), highlight the strong connection between paleogeographic events and earthworm evolution and divergence. A more robust approach to time-calibrated phylogenies in earthworms (hindered by the lack of body fossils) and the integration of different paleogeographic reconstructions could illuminate both the origin of palearctic earthworms (hormogastridae, Lumbricidae) and the geological history of the Western Mediterranean terranes from the Late Cretaceous to the Neogene.…”

“…The remaining trees were combined and summarized on a 50% majority-rule consensus tree. Clade support (Bootstrap and Posterior probability) values over 70% and 90% respectively were considered as high (see Marchán et al 2018;De Sosa et al 2019).…”

Distribution and genetic diversity of two earthworms, Helodrilus oculatus and Satchellius mammalis (Clitellata: Lumbricidae) in Scandinavia

“…The trees were drawn in FigTree 1.4.2 (Rambaut 2014) and further edited in Adobe Illustrator and Inkscape. Taxon names are updated in accordance with Szederjesi and Csuzdi (2016), Csuzdi et al (2017), and Marchán et al (2018). The alignments and output files from the analysis are available at https://github.com/Svante-Martinsson/Helodrilus_Satchellius.…”

Local adaptation fuels cryptic speciation in terrestrial annelids

“…Cryptic diversity is widespread in annelids (e.g., Struck et al, 2017), particularly amongst earthworms (King et al, 2008;Novo et al, 2010;Shekhovtsov et al, 2013;Taheri et al, 2018). One of the most studied cryptic species groups among these animals is the former Hormogaster elisae Álvarez, 1977 (Annelida, Oligochaeta, Hormogastridae), recognized as the genus Carpetania after Marchán et al (2018b). Six highly divergent cryptic lineages were identified using a set of mitochondrial and nuclear markers (Marchán et al, 2017), but their validation as species and consequent description has been hindered by the absence of clear-cut limits between the putative species.…”

“…Those lineages display strong spatial isolation with non-overlapping ranges separated by narrow borders and clear hints of reproductive isolation shown by cross-breeding experiments (Marchán et al 2017). In addition, slight variation in some cryptic morphological characters (genital chaetae, relative position of septa and spermathecae) was found promising but was not fully tested in a comparative framework (Marchán et al, 2017(Marchán et al, , 2018b. These characteristics make the Carpetania complex a promising model to further explore the underlying evolutionary phenomena shaping cryptic speciation in soil-dwelling lineages.…”