Two new species of parasitic copepods from the genera Nothobomolochus and Unicolax (Cyclopoida: Bomolochidae) from Australian waters

Abstract

A 2016 collaborative survey of commercial fish parasites in Moreton Bay, Queensland, Australia led to the discovery of two new species of parasitic copepods belonging to the family Bomolochidae. Females of Nothobomolochus johndaveorum n. sp. were found attached to the gill filaments of Gerres subfasciatus and Gerres oyena. The new species most closely resembles N. leiognathicola and N. quadriceros. All 3 species possess 3 modified setae on the first antennulary segment that are approximately the same length and have a robust seta on the second antennulary segment adjacent to the 3 modified setae giving a superficial appearance of 4 modified setae on the antennule. The new species can be distinguished from these two species in its possession of longer inner setae on the first two endopodal segments of leg 4: the seta on endopodal segment 1 extends past the midline of the distal segment in the new species vs to the proximal margin of the distal segment in the other two species, and the seta on segment 2 extends well beyond the distal margin of the endopod in the new species vs just to the margin in the other two species. Females and males of Unicolax longicrus n. sp. were found in the nasal sinuses of Sillago maculata and Sillago ciliata. The new species differs from 6 of its 7 congeners in having a leg 4 exopod formula of II, I, 4 rather than II, I, 3 or II, I, 5. The new species resembles U. anonymous in this feature, but differs in its possession of a leg 5 that is relatively longer and less wide, and, whereas U. anonymous possesses inner and outer distal spines on leg 5 that are approximately the same length, those of the new species are relatively longer and asymmetrical. Unicolax longicrus n. sp. is unique among its congeners in its possession of a leg 4 with highly elongated endopodal segments 2 and 3, from which its name is derived. In addition to describing the two new species, host and locality reports for all species of Nothobomolochus and Unicolax are reviewed.