Adlardia novaecaledoniae n. g., n. sp. (Digenea: Cryptogonimidae) from the fork-tailed threadfin bream Nemipterus furcosus (Val.) (Perciformes: Nemipteridae) off New Caledonia.

Adlardia novaecaledoniae n. g., n. sp. (Digenea: Cryptogonimidae) is described from the fish Nemipterus furcosus (Val.) (Perciformes: Nemipteridae) from off New Caledonia (South Pacific). Adlardia n. g. is distinguished from all other cryptogonimid genera by the combination of an elongate body, the presence of oral spines, intestinal caeca that open via ani at the posterior end of the body, a highly lobed ovary, oblique testes that are located in the mid-hindbody, vitelline follicles that extend from midway between the testes and ovary to midway between the ovary and ventral sucker, and an excretory vesicle that bifurcates dorsal to the ovary and reunites immediately anterior to the pharynx. A. novaecaledoniae n. sp. is the only cryptogonimid that has been reported with an excretory vesicle that reunites anterior to the pharynx. Siphoderina elongata (Gu & Shen, 1979) Miller & Cribb, 2008 is transferred to Adlardia as A. elongata (Gu & Shen, 1979) n. comb. based on morphological and ecological (host group) agreement with A. novaecaledoniae. Bayesian inference analysis of LSU rDNA revealed that A. novaecaledoniae nested well within a clade containing cryptogonimid taxa known almost exclusively from haemulid and lutjanid fishes, suggesting that host-switching between teleosts of the Haemuloidea, Lutjanoidea and Sparoidea may have been common in the evolutionary history of this system.