The cradle of giants: insights into the origin of Scherotheca Bouché, 1972 (Lumbricidae, Crassiclitellata) with the descriptions of eight new species from Corsica, France

Scherotheca Bouché, 1972 is a highly diverse genus of Lumbricidae Rafinesque-Schmaltz, 1815, broadly distributed from Northern Italy and Corsica Island to the Pyrenees and Northeastern Iberian Peninsula. A recent survey of earthworm species diversity in Corsica resulted in the identification of 12 operational taxonomic units (OTU) within Scherotheca and the closely related genus Eumenescolex Qiu & Bouché, 1998, based on both morphological characters and COI barcodes. In this work, we complete molecular analyses to provide a dataset including four DNA markers (COI, 16S, 28S and ND1) and analyze it through Bayesian phylogeny reconstruction and barcode gap analysis. Our results highlight the existence of eight phylogenetically and morphologically distinct species, new for science, which we described herein as Scherotheca altarocca Marchán, Decäens & Domínguez, n. sp., Scherotheca marceli Marchán, Decäens & Domínguez, n. sp., Scherotheca darioi Marchán, Decäens & Domínguez, n. sp., Scherotheca boccaverghju Marchán, Decäens & Domínguez, n. sp., Scherotheca qiui Marchán, Decäens & Domínguez, n. sp., Scherotheca litoralis Marchán, Decäens & Domínguez, n. sp., Scherotheca capcorsana Marchán, Decäens & Domínguez, n. sp. and Scherotheca mausoleana Marchán, Decäens & Domínguez, n. sp. The diversity of the genus in Corsica has thus increased from four to 12 species. In addition, Eumenescolex emiliae Qiu & Bouché, 1998 appears phylogenetically nested within the Corsican Scherotheca, justifying amendment of the name to Scherotheca emiliae (Qiu & Bouché, 1998) n. comb. leading to 13 Corsican species in the genus. We further discuss diversity patterns, phylogenetic relationships and biogeographical history of the genus in the Corsica Island.