Two new species of diplectanid monogeneans infecting Malabar grouper Epinephelus malabaricus and orange-spotted grouper E. coioides cultured on Ishigaki Island, Okinawa, Japan.

Abstract

Descriptions are given for two new diplectanid monogeneans, Cryptoplectanum ishigakiense n. g., n. sp. collected from Malabar grouper Epinephelus malabaricus (Bloch & Schneider) and orange-spotted grouper Epinephelus coioides (Hamilton), and Pseudorhabdosynochus yaito n. sp. from E. malabaricus, both cultured on Ishigaki Island, Okinawa, Japan. Cryptoplectanum n. g. differs from its most similar genus Pseudorhabdosynochus Yamaguti, 1958 by having an unsclerotized vagina and lacking a quadriloculate organ. Cryptoplectanum ishigakiense n. sp. differs from its most similar species Diplectanum maa Justine & Sigura, 2007 by possessing a small, funnel-shaped penis and tegumental scales in posterior body, whereas D. maa has a larger, spoon-shaped penis and lacks tegumental scales. Pseudorhabdosynochus yaito n. sp. is most similar to P. manifestus Justine & Sigura, 2007, but can be differentiated by the shape of the quadriloculate organ; in the new species, all chambers are of equal width and equally sclerotized, while in P. manifestus the chambers became gradually narrower toward the cone and the fourth chamber is more heavily sclerotized than the anterior three. Molecularly, C. ishigakiense n. sp. forms a clade with Diplectanum grouperi Bu, Leong, Wong, Woo & Foo, 1999, both constituting a lineage closely related to the main Pseudorhabdosynochus clades. Both D. maa and D. grouperi possess the penis and vagina characteristic of the newly proposed genus Cryptoplectanum, and thus are assigned to Cryptoplectanum maa n. comb. and C. grouperi n. comb., respectively.