New Echinoderes (Kinorhyncha: Cyclorhagida) from Mexico: Molecular barcoding demonstrate species delimitation between highly similar morphospecies

Abstract

Two new species of Echinoderes are described from Mexico. Echinoderes abeli sp. nov. is described from the archipelago Islas Marias in the Mexican Pacific Ocean west coast. The species is characterized by very short and stout lateral terminal spines, middorsal spines on segments 4 to 8 and lateroventral spines on segments 6 to 9, lateroventral tubes on segment 2 and 5, midlateral tubes on segment 4, and sublateral ones on segment 8, and in laterodorsal positions on segment 10, as well as glandular cell outlets type 2 in subdorsal positions segment 2. The second new species, Echinoderes wilberti sp. nov. is described from the Caribbean coast in Yucatan. The new species show great resemblance with another species, Echinoderes horni, that occurred at the same locality. The only notable difference is a pair of subdorsal tubes on segment 2, present in E. wilberti sp. nov. only. However, barcoding of COI demonstrated the two morphospecies differed genetically more than 8%. This result shows that small morphological differences might be supported by much more conspicuous molecular differences. Based on the high level of morphological similarity between E. wilberti sp. nov. and E. horni, as well as a third Caribbean species, Echinoderes parahorni, a species group, the E. horni group, is proposed to accommodate this potentially monophyletic group of species.This article is registered at www.zoobank.org under urn: lsid: zoobank.org:pub: 5AE5C820-C922-492B-83F3-66C957E53453.