Molecules vs. morphology ‒ is Eratigena atrica (Araneae: Agelenidae) one species or three?. Molecules vs. morphology ‒ is Eratigena atrica (Araneae: Agelenidae) one species or three?

DNA analyses may reveal grouping of species that are discordant with phylogenies constructed using morphological characters. Here we examine the taxonomic status of what, historically, was called the Tegenaria atrica group of large house spiders: T. atrica, T. saeva and T. gigantea. A recent phylogenetic analysis, based largely on European material, proposed that this group should be transferred to a new genus, Eratigena, and that a lack of morphology and mtDNA distinctiveness between constituent members indicated a single species, Eratigena atrica. The new genus is well-supported but the concatenation of the three species into one is inconsistent with information from Britain. Here we sequence new specimens from Britain, and examine morphologically both this and additional material from Britain, continental Europe and North America. We test the hypothesis that although the three species are distinct in Britain, in continental Europe hybridisation may have led to their fusion into a single entity. Our mtDNA sequence data confirm the previously demonstrated small genetic distances and complex phylogenetic relationships between taxa. However, we show that three distinct morphological groupings exist across the range of the species and that as a result the specific names atrica sensu stricto, saeva and gigantea should be resurrected.