New morphological and molecular data on the little-known pontellid Calanopia media Gurney, 1927 (Crustacea, Copepoda, Calanoida) from the Red Sea, with notes on its diel vertical distribution.

ABSTRACT

As a part of the routine neritic zooplankton collection program in Obhur Creek (central Red Sea, Saudi Arabia), specimens of a pontellid calanoid copepod, Calanopia media Gurney, 1927, were observed and studied. Since the original description was rather brief and drawings limited, especially of mouthparts and legs, which were not illustrated and described, the species is here fully redescribed. Red Sea specimens showed considerable variation in the female genital compound somite, the right caudal ramus and leg 5, as well as in the presence of a medial knob ventrally on the male right prosomal corner. DNA sequences of mtCOI of different specimens did not show any significant differences and supported their identity as one species. Calanopia media exhibited clear diel vertical migration, with high densities of 106 and 150 ind. m-3 during sunset (600 pm; UTC+3) and midnight (1200 am; UTC+3) collections, respectively. However, this species was not observed in other zooplankton collections from the surface to 20 m depth, at 600 am and 1200 pm (UTC+3).