New records on the rich loriciferan fauna of Trezen ar Skoden (Roscoff, France): Description of two new species of Nanaloricus and the new genus Scutiloricus

Loricifera is a phylum of microscopic animals that inhabit marine environments worldwide. Named after their conspicuous and protective lorica, the phylum was first described from Roscoff (France) in 1983 and, hitherto, it contains only 40 species. Based on data collected from Roscoff during the past four decades, we here describe two new species of Nanaloricus, namely Nanaloricus valdemari sp. nov. and Nanaloricus mathildeae sp. nov., as well as a new genus and species, Scutiloricus hugoi gen. et sp. nov. Adults of N. valdemari sp. nov. are distinguished by a pair of unique cuticular ridges, here referred to as longitudinal stripes, spanning laterally along the anterior two thirds of the dorsal lorical plate. N. mathildeae sp. nov. is characterized by strong sexual dimorphism. Specifically, the branches composing the multiform male clavoscalids are much broader as compared to other Nanaloricus species. The two new Nanaloricus species are both characterized by unique sensory organs associated with the double trichoscalids. The size and exact position of these organs differ between the two species. Adults of Scutiloricus hugoi gen. et sp. nov. are characterized by, among other features, a square lorica composed of six cuticular plates with a total of 14 anterior spikes, of which 12 have transverse cuticular ridges and thus appear fenestrated; laterodorsal flosculi arranged linearly; a posterior lorical region characterized by an anal field with a small anal cone flanked by a pair of spurs. Notably, mature females are characterized by a pair of seminal receptacles, a character not previously reported in Loricifera. We discuss the new findings and compare N. valdemari sp. nov. and N. mathildeae sp.nov. with other species assigned to genus Nanaloricus. The distinguishing features of Scutiloricus hugoi gen. et sp. nov. are discussed from a comparative perspective with the other genera of family Nanaloricidae.