Integrative Taxonomy Reveals New Insights into the Species Validity of the Neocaridina davidi-N. denticulata-N. heteropoda Complex and Mitogenomic Phylogeny of Caridean Shrimps

Abstract

The genus Neocaridina, originating from East Asia and representing a small-size landlocked shrimp group of the family Atyidae, is an important group of ornamental shrimps and plays significant ecological roles in their natural habitats. Owing to the considerable variability of the taxonomic characters it employed, Neocaridina is constantly under revision, and the validation of several species is currently questionable. In the present study, several Neocaridina shrimps were collected from the Baiyangdian drainage area. Through morphological examination, they exhibited delicately diagnostical differences in the dactyli of the third pereiopod and the endopod of the first and second pleopod and were classified into morph A, morph B and morph C. According to the literature description, morph A and morph C were identified as N. denticulata denticulata and N. denticulata sinensis, respectively. Among them, morph B presents an intermediate state between morph A and morph C. Subsequently, we determined the mitogenomes of morph A, morph B and morph C. Based on the morphological characteristics, genetic variation and phylogenetic tree, we contend that N. davidi, N. d. denticulata, N. d. sinensis and N. heteropoda should belong to the same species, and we propose retaining the name N. denticulata. The reconstructed mitogenomic phylogeny indicated that the monophyly of several genera within Atyidae has been challenged, suggesting that the established classification of Atyidae requires substantial taxonomic revision at all taxonomic levels. Furthermore, the tree’s topologies supported Atyidae at a deeper base within Caridea. More comprehensive taxon sampling is still needed to resolve the explicit internal relationships among Caridea.