Abstract
Two species of sea lice are reported from the golden snapper Lutjanus johnii (Bloch) in Australian waters. One was represented by chalimus larvae, adult males and extremely slender females in which the genital complex is scarcely wider than the fourth pedigerous somite. These females are adult as they carry paired spermatophores and are identified as Caligus dussumieri Rangnekar, 1957 on the details of their appendages. Caligus dussumieri was formerly placed in the genus Sinocaligus Shen, 1957 but the characters supporting the validity of this genus are not robust, so it is here proposed to treat it as a junior subjective synonym of Caligus and transfer its species as: Caligus formicoides Redkar, Rangnekar & Murti, 1949, Caligus dussumieri Shen, 1957, Caligus caudatus (Gnanamuthu, 1950) new combination and Caligus timorensis (Izawa, 1995) new combination . All these species can be placed in the C. bonito -species group within Caligus . Caligus rivulatus Pilla, Vankara & Chikkam, 2012 is recognized as a junior subjective synonym of C. dussumieri . A new species, C. auriolus n. sp. is also described and this is placed in the C. diaphanus species-group. A key to species of this species-group is provided which indicates that C. auriolus n. sp. is most closely related to C. stromatei Krøyer, 1863 but the latter can be distinguished by the slender abdomen of the female and by the more complex myxal process on the maxilliped in the male.