Agarna malayi Tiwari 1952 (Crustacea: Isopoda: Cymothoidae) Parasitising the Marine Fish, Tenualosa toli (Clupeidae) from India: Re-description/description of Parasite Life Cycle and Patterns of Occurrence.

Panakkool Thamban Aneesh, Kappalli Sudha, Ameri Kottarathil Helna, and Gopinathan Anilkumar (2018) This paper re-describes the female stage of Agarna malayi Tiwari 1952, a protandrically hermaphroditic parasitic cymothoid, and describes the remaining life cycle stages for the first time. The re-description (female phase) of A. malayi was made based on the type specimens deposited by Tiwari (1952) in the National Zoological Collections of the Zoological Survey of India (NZC-ZSI) and data obtained from several live specimens collected from Ayyikkara Fish Landing Centre (11°51'N, 75°22'E, of Malabar Coast, India) and Marina Beach (13.0500°N, 80.2824°E, Bay of Bengal, India). General morphology, mouthparts and appendages of the species' life cycle stages such as larvae, juveniles, male and transitional stages are also reported for the first time. We closely observed 80 marine fish species belonging to 35 different families to identify the potential host of A. malayi, and only recovered the parasite from one fish, Tenualosa toli, signifying A. malayi's oligoxenous host specificity; the prevalence and intensity of parasitisation is 17.3 and 1.86%, respectively. The present paper also discusses sequential life cycle stages of the species.

A case of persisting massive infection of Scomberomorus commerson, a commercially exploited scombrid fish, with Cybicola armatus (Copepoda: Siphonostomatoida: Pseudocycnidae).

During an extensive survey of fish parasites along the Malabar coast of India we observed exceptionally high or even massive infection of the narrow-barred Spanish mackerel, Scomberomorus commerson (Scombridae), with parasitic copepods Cybicola armatus. Such infection has not hitherto been reported. The copepods occurred on the gills of its host and the infection persisted for many years (the survey lasted from January 2010 to July 2014). The overall prevalence was very high (95%); out of a total of 981 fish studied, 933 were infected, and the maximum intensity reached 42. The highest rate of infection (prevalence 99.2%) was observed in medium sized fish (36.0-79.9 cm). We found this parasite only on S. commerson even though we examined 81 fish species, including five of the family Scombridae. Interestingly, the parasite exhibits strict site specificity and microhabitat preference. A significant proportion of them was seen attached to pseudobranchs rather than to main gill arches. Significantly, the body size of the parasite was positively correlated with that of the host fish. Our SEM micrographs contributed new facts to this copepod's morphology by illustrating for the first time the ventral part of its cephalothorax, illustrating the nature of attachment, and by finding a new structure - a premaxillary pad. We demonstrated the haematophagous nature of C. armatus by finding and documenting the host's blood cells in the parasite's intestine.

Multiple parasitic crustacean infestation on belonid fish Strongylurastrongylura.

Simultaneous multiple infestation of parasitic crustacean species involving a cymothoid isopod, Cymothoafrontalis Milne Edward, 1840 and four species of copepods such as Lernanthropustylosuri Richiardi, 1880, Caligodeslacinatus Kroyer, 1863, Bomolochusbellones Burmeister, 1833 and Dermoergasiluscoleus Cressey & Collette, 1970 was frequently noticed on spot-tail needlefish, Strongylurastrongylura (Belonidae) captured from the Malabar coast (Kerala, India) during the period from April 2011 to March 2012. All the 43 fishes (Strongylurastrongylura) collected, were under the hyper-infection with parasitic crustaceans; a total of 388 parasitic crustaceans including 57 Cymothoafrontalis, 252 Lernanthropustylosuri, 31 Caligodeslacinatus, 24 Bomolochusbellones and 32 Dermoergasiluscoleus were recovered from the host fish. 4 members (9.30%) of host fish were under quadruple parasitism, in two different combinations. Seventeen (39.53%) host fishes showed triple parasitism and 20 (46.51%) members exhibited double parasitism, with four and five parasitic combinations respectively. Remaining two (4.65%) fishes were parasitized only by the copepod, Lernanthropustylosuri. The infestations by all recovered parasitic crustaceans were highly site specific. The damage caused by the parasitic crustaceans was also discussed.

Seasonal fluctuation of the prevalence of cymothoids representing the genus Nerocila (Crustacea, Isopoda), parasitizing commercially exploited marine fishes from the Malabar Coast, India.

The presently reported study investigated seasonal fluctuations in the prevalence in four species of Nerocila infesting commercially exploited marine fishes representing the families Engraulidae, Clupeidae and Ambassidae, from the Malabar coast (Kerala, India). Seven of 56 fish species belonging to 23 families were infested by either one or two species of Nerocila. All the collected Nerocila species showed significant seasonal fluctuations in the prevalence of infestation, reaching maximum from October through April and minimum (or total absence of the parasites) from May through September. Such fluctuations were analyzed based on environmental parameters. Body surface, postero-ventral side of the head and the lateral line of the host fish form the major infestation site for the recovered Nerocila species. Skin lesion and hemorrhages were observed on the fish parasitized with these cymothoids.