A new species of the dentipes-subgroup of Triconia and a redescription of T-giesbrechti and T-elongata (Copepoda: Cyclopoida: Oncaeidae) from the tropical Pacific and the Korea Strait

Abstract

A new species of Triconia in the family Oncaeidae, Triconia pacifica sp. nov., and a new form variant each of Triconia giesbrechti Bottger-Schnack and Triconia elongata Bottger-Schnack are described from two sites in the Pacific. Triconia pacifica can be distinguished from its sibling Triconia dentipes (Giesbrecht) by (1) morphometric characters, including the proportional lengths of distal endopod spines of swimming leg 4, and the relative length of the outer basal seta on P5, and by (2) a number of micro-structures on the appendages. The Pacific specimens of T.elongata and T.giesbrechti resemble the typical forms in morphometric characters, with some minor differences in proportional spine lengths on the swimming legs, and differ in a few micro-structures. The hitherto unknown male of T.giesbrechti is newly described. For all species/forms described, the intraspecific variability of proportional spine lengths on the endopods of P2-P4 is examined and discussed.