Dear Rodrigues, Those are probably Caligus and  structures photos do not look full.(Some appendages of Caligus  Female: a) Antenna; b) Furca; c) Second endopod; d) Second exopod; e)Fourth leg; f) Male: genital complex, abdomen and caudal rami.

Materials and methods

Parasitic copepods were immediately

preserved in 70% ethanol. Subsequently, specimens

were cleared in lactic acid for 2 h prior to examination

using an Olympus SZX16 dissecting microscope and

Olympus BX51 compound microscope. Specimens

were dissected on glass-slides and mounted as temporary

preparations in lactophenol.

Hola Alfredo, te sugiero que observes la parte del cefalon, (parte anterior del cefalotorax), dos estructuras circulares denominadas lunulas, que es caracteristica distintiva del genero Caligus. Si no las presenta es probable que se trate de alguna especie del genero Lepeophtherius.

Saludos!

start with: it is not Caligus, looks like Lepeophtheirus, possibly pravipes but would need to have a look at some leg structures and sternal furca to confirm. Caligus have cuticular suction cups called lunules. go on line and get Kabata and Margolis 1988: Guide to the Parasites of Fishes of Canada. I realize that this is not your area of the world but it gets you started with some good keys explaining (and showing) what are the defining characteristics of each suborder and genera; plus all the references. If you cannot get it, send me your email and i can send you a copy. 

Yes Moira is correct, its not Caligus, most likely Lepeophtheirus. Taxonomy is complicated by the huge number of synonyms.  There are two people who can probably help you: Geoff Boxshall at the British Museum of Natural History, or Danny Tang (Orange County sanitation district) (see researchgate entry). Danny was a student of mine, and is a very good Copepod taxonomist.

Dear Alferido,

My ph.D and most of my research papers is on Crustacean parasites of fish particularly marine species .I Identified more than 11 Caligiid species in Egypt. So you can send me the data about the host by mail and also I can help in identification by many ways.

my mail: [email protected]

I agree, it is not Caligus but Lepeophtheirus. You will have to do dissections in order to try and identify it to species level. I will suggest that you first check which Lepeophtheirus species has been reported from Epinephelus hosts and start by comparing your specimens to those.

 Yes, I can help you identify this is Lepeophtheirus. it is not Caligus  I will suggest that you first check which Lepeophtheirus species (for examples:Lepeophtheirus plectropomi, Lepeophtheirus epinepheli, Ldissımulatus ...)  has been reported from Epinephelus hosts and start by comparing your specimens to those.Taxonomy is complicated by the huge number of synonyms.  There are three people who can probably help you, or Geoff Boxshal,dany , argun   : Geoff Boxshall at the British Museum of Natural History, Argun özak was a student of mine, and is a very good Copepod taxonomist.  Geoff Boxshal  too busy writing books these days. but I can talk to his students Argun .Now working withBoxshal in England. This call will come to in Turkey.So you can send me the data about the host by mail and also I can help in identification by many ways

Dr Erkin Koyuncu

Mersin University 

[email protected]

.  

Thanks everyone for the replies! 

I will take a look on the Lepeophtheirus species, and search a little more for previous copepods isolated from Dusky groupers. In some weeks I expect to dissect some of those for a clearer identification. I might aswell send you an email with details, from the parasite and the host.

Best regards,

Alfredo

Dear Alfredo,

This is the photo of caligus species I recorded from groupers in Egypt and you can notice the difference between the anterior part of Caligus and  of your Lepeophtheirus spp.