The widespread European centipede species Lithobius (Monotarsobius) crassipes L. Koch, 1862 was revised using an integrative approach incorporating sequence data and morphology. The partial mitochondrial cytochrome c oxidase subunit I (COI) barcoding gene was amplified and sequenced for 21 individuals from northern Spain, France and Germany as well as for individuals of three other species of the subgenus Monotarsobius Verhoeff, 1905. The dataset was used for molecular phylogenetic analysis and genetic distance determination. In addition, Monotarsobius specimens from more than 100 localities in northern Spain, France, and Germany were morphologically investigated. Both morphological and molecular data indicate that specimens from the Navarre and Gipuzkoa provinces, northern Spain, represent a distinct pseudo-cryptic species, only differing in some minor characters from L. crassipes. The new species L. (Monotarsobius) crassipesoides sp. n. is described and compared to L. crassipes in detail using morphology and morphometric statistics for body, head, and antennae length, number of ocelli and coxal pores, as well as the starting leg for legpair spines Vmt and DaP. The Iberian and European records of L. crassipes are discussed. The subspecies L. crassipes morenoi Garcia Ruiz, 2014 from Southern Spain is elevated to species as L. morenoistat. n. A checklist, distribution map and key to all five species of Monotarsobius of the Iberian Peninsula are presented.
Keywords: COI; checklist; key; new species; pseudo-cryptic diversity; taxonomy.