An integrative approach to the delimitation of pseudocryptic species in the Eucyclops speratus complex (Copepoda, Cyclopoida) with a description of a new species

By

Novikov, Aleksandr
Sharafutdinova, Dayana
Abramova, Ekaterina
Mayor, Tatyana
Chertoprud, Elena

Type

Article

Date of Publication

2025

Original Publication

ZooKeys

Volume

1226

Pages

217--260

Subjects

Biodiversity , cryptic species , cuticular pores , Cyclopidae , Eucyclops sibiricus , geometric morphometrics , integrative description , linear morphometrics

Contributed by

Pensoft Publishers

Language

English

Published by

Sofia, Bulgaria Pensoft Publishers

Identifiers

DOI: https://doi.org/10.3897/zookeys.1226.138389

 

Abstract

Eucyclops speratus (Lilljeborg, 1901) (Copepoda, Cyclopoida, Cyclopidae) was studied using various methods. Molecular genetic methods (comparison of COI and ITSn molecular markers) have shown that this species represents a species complex, and the following methods were used to search for differences between the species: analysis of qualitative and quantitative characters, linear morphometrics, landmark-based geometric morphometrics, and integumental pore pattern of the cephalothorax. Eucyclops sibiricussp. nov. from Middle Siberia is described. The two studied species can be considered pseudocryptic; the main morphological difference between the species is the number of setules on the inner side of the first and second exopod segments of the fourth pair of swimming legs: E. sibiricussp. nov. has 6–10 and 7–17 setules, respectively; E. speratus has 0–3 and 0–6 setules, respectively. The morphometry and integumental pore pattern of the cephalothorax were ineffective for identification and separation of species. The existing previous records of E. speratus were also analyzed, and the records of this species in the Irkutsk region (Russia), as well as in Japan and Korea, are attributed to E. sibiricussp. nov.