Sea lice Lepeophtheirus spinifer, Tuxophorus sp. and Caligus sp. infections on wild-caught queenfish Scomberoides commersonnianus from northern Australia

Caligid sea lice (Copepoda: Caligidae) from golden snapper Lutjanus johnii (Bloch) in Australian waters, with the recognition of Sinocaligus Shen, 1957 as a junior synonym of Caligus Müller, 1785

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.

Seasonal population dynamics of Lepeophtheirus spinifer and Neobenedenia sp. coinfecting snubnose pompano (Trachinotus blochii) breeders in marine cages in the Philippines

Studies on the biology and ecology of sea lice are lacking in tropical regions such as in Southeast Asia where finfish cage farming has grown dramatically in the past decades. This study investigated the seasonal population dynamics of ectoparasites infecting captive snubnose pompano (Trachinotus blochii) breeders in marine cages in the Philippines. The pompano breeders were found to be naturally coinfected with caligid copepod Lepeophtheirus spinifer and capsalid monogenean Neobenedenia sp. These breeders were monitored and examined bimonthly (n = 10 per sampling) from September 2017 to May 2018, covering the warm season and cold season in the Philippines. Our results clearly show that L. spinifer population maintain a 100 % prevalence throughout warm and cold seasons however, mean abundance and intensity increased only during the cold months (early November to early March) and displayed an oscillating trend during this period. Highest mean intensity was recorded in early January (221.4 ± 24.6; temperature = 27.5 ± 0.3 °C; salinity = 34.8 ± 0.3 ppt) while the lowest mean intensity was recorded during the warm months dipping to 12.5 ± 1.9 in early May (temperature = 30.5 ± 0.3 °C; salinity = 30.3 ± 0.3 ppt). The prevalence of adult and pre-adult was high throughout the monitoring period at 70-100 % except at the start of summer (late March to early May) for pre-adult (30-90 %). In comparison, the chalimus stages were only observed during the cold months specifically from early November to late January with prevalence of 40-80 %. The highest mean abundance (3.4 ± 0.7) and mean intensity (4.3 ± 0.6) was in early November which coincided with the first peak of the total L. spinifer population. Neobenedenia sp. occurred year-round with no significant changes in the population mean abundance and mean intensity between warm and cold seasons. This study presents comprehensive information on the seasonal population dynamics of L. spinifer and Neobenedenia sp. in the Philippines, providing valuable insights on the ecology of caligid sea louse which is fundamental in the formulation of control and management strategies of these economically significant ectoparasites.