New records of two parasitic cymothoids from Indian fishes

Phylogeny and ultrastructure of Elthusa raynaudii (Isopoda, Cymothoidae) firstly recorded from the invasive silver cheeked toadfish (Lagocephalus sceleratus) (Gmelin 1789) in eastern Mediterranean Sea coast

With the opening of the Suez Canal in 1869, many changes have occurred in the Mediterranean Sea ecosystem so became a home to many invasive Lessepsian marine species that have migrated from the Red Sea. About 500 marine species including pufferfish have immigrated and rapidly established a population in the Mediterranean Sea causing significant impact on its ecosystem and fisheries sector. The parasitic fauna of these pufferfish has scarcely been studied in the Mediterranean Sea and also in their native habitat. During this surveillance study on the invasive pufferfish species from the Egyptian Mediterranean coast, the female cymothoid isopod Elthusa raynaudii was detected from the branchial cavity and also in the buccal cavity of 23.9% of the examined Lagocephalus sceleratus. The isolated isopod species was firstly identified and described through electron microscopy and molecular phylogeny based on the sequences of mitochondrial 16S rRNA gene. Additionally, the description of eggs, embryonic stage, and manca of E. raynaudii was firstly provided. The pathological impact on the infested fish tissues was investigated and revealed curling and loss of secondary gill lamellae in addition to mucous exudates in between the gill filaments and granuloma formation in the gill arch. The study provided the first report of L. sceleratus as a new host for the isopod E. raynaudii collected from the Egyptian Mediterranean coast as a new locality record. The role of the Lessepsian invasive pufferfish in transmitting parasites to the native fish species was discussed.

New Records of Fish Parasitic Isopods (Crustacea: Isopoda) from the Gulf of Thailand

From a total of 4140 marine fishes examined, eight species of parasitic isopods were reported from marine fishes in the Gulf of Thailand. These isopods were identified in two families, Corallanidae (Argathona macronema and Argathona rhinoceros) and Cymothoidae (Cymothoa eremita, Cymothoa elegans, Smenispa irregularis, Nerocila sundaica, Norileca indica and Norileca triangulata). Most of these parasitic isopods were found in the buccal cavity of their fish hosts with one host recorded as follows: C. eremita was found from Nemipterus hexodon, C. elegans was found from Scatophagus argus, N. sundaica was found from Saurida tumbil. The majority of the isopod specimens recorded in this study was S. irregularis, which was found in the buccal cavities of five host fish, Pampus argentius, Alepes melanoptera, Caranx hippos, Parastromateus niger and Terapon jarbua, with a prevalence of 11.67%, 10.43%, 9.78%, 6.10% and 4.21%, respectively. Argathona rhinoceros was found in the nasal cavity and branchial cavity of Epinephelus coioides, whereas A. macronema and N. triangulata were found on the skin of Epinephelus coioides and Seriolina nigrofasciata, respectively. The highest species diversity was found in E. coioides, which harbored two species of parasitic isopods, A. macronema and A. rhinoceros. Cymothoa eremita, C. elegans, S. irregularis and N. triangulata were recorded for the first time in the Gulf of Thailand. The reported discovery of C. eremita, S. irregularis, N. sundaica and N. triangulata in their fish hosts were new recorded hosts. Moreover, A. macronema and N. triangulata were found for the first time in the central Indo-Pacific region.

Prevalence of cymothoid isopods (Crustacea, Isopoda) and proximate analysis of parasites and their host fishes, Southeastern India

Cymothoid isopods (Crustacea, Isopoda) are considered as potential threat to the health of different fish species. In order to evaluate the prevalence and proximate analysis of Cymothoid isopods and its host, an investigation was carried out fish species belonging to families Hemiramphidae and Belonidae in the Palk Bay region, Southeastern India. A total of 1265 individuals of teleost fish belonging to family Hemiramphidae species, Hemiramphus far (462), H. archipelagicus (78), and H. lutkie (277) and another family Belonidae species, Tylosurus crocodilus (448), were examined for cymothoid ectoparasitic infestation. Prevalence in H. far was the highest (39%) for the cymothoid Mothocys plagulophora, while T. crocodilus was most infested (13%) with Mothocys renardi, H. far and H. lutkie were not infested by M. renardi while T. crocodilus was not infested by M. plagulophora. Proximate analysis showed reduced level of protein in parasite infested fish compared with non-infested individuals. However, carbohydrate and lipid concentrations were lower in infested fish than non-infested individuals. Proximate analysis values in the two parasites of Mothocys species were similar, and these values were comparable to those unaffected fish species indicating that parasites were well nourished. The proximate analysis of isopod parasite M. plagulophora showed 21.6 ± 7.7, 1.26 ± 0.05, 5.49 ± 1.06% of protein, carbohydrate and lipid respectively, and in M. renardi, 21.09 ± 6.6, 1.32 ± 0.12, 5.83 ± 0.72% of protein, carbohydrate and lipid respectively. Cadmium levels were similar between affected and non-affected fish individuals and among species. The Pb levels were comparable among all T. crocodilus individuals, but the levels of Cd not showed much variation between affected and unaffected individuals in all four fish species.

First record on the occurrence of Ryukyua circularis (Pillai, 1954), a parasitic cymothoid (Crustacean: Isopoda) infesting the clupeid fish Amblygaster sirm (Walbaum) from Andaman Islands, India

In the present study, occurrence of branchial parasitic cymothoid, Ryukyua circularis from the marine finfish, Amblygaster sirm is reported for the first time from Andaman Islands. Morphological characterization was carried out which confirmed the parasite as R. circularis. Molecular characterization using 28S rDNA revealed 443 bp sequence which has been submitted to NCBI GenBank under the accession no. KX090447. Ten female and one male parasite (R. circularis) were collected from the branchial cavity of the individual host fishes (A. sirm). The displacement of gill filament and cavity formation in the gill chamber of the host fish was observed. The report of this species from Andaman Islands gives further information on its geographic range extension, since they are currently known from West coast of India and Thailand.

High prevalence and infestation of Mothocya renardi (Isopoda, Cymothoidae) in marine fish Strongylura leiura (Bleeker 1850)

Cymothoid isopods are parasites that cause severe damage to the fish species. The present study was focused to carry out the parasitic infestation on the one of the important marine fish Strongylura leiura during the 2 years period between June 2009 and May 2011. 272 fish specimens collected and about 157 (57.72 %) fishes were infested by the cymothoid which were concealed under the gill arches of the host. Infested parasite was identified as Mothocya renardi. The prevalence rate of parasites during different seasons of the range of host specificity of isopods was studied. Variation of infestation rate also depends on the size, length and weight of the host. The sites of infestation by the parasitic crustaceans are highly specific. The infestation had affected the normal growth of the host fish and also probably leads the high levels of secondary infections.

Redescription of poorly known species of Ceratothoa Dana, 1852 (Crustacea, Isopoda, Cymothoidae), based on original type material

Due to the difficulty in accurately identifying cymothoids, these parasitic isopods are often incorrectly named or confused with other species. Within the genus Ceratothoa, a number of recent studies have aimed at clarifying some of the problematic species; however, several of the less studied species still require revision. This paper redescribes, from type material, several poorly known Ceratothoa species including Ceratothoaangulata, Ceratothoacapri, Ceratothoacarinata, Ceratothoacollaris, Ceratothoagilberti, Ceratothoagobii, Ceratothoaguttata, Ceratothoaitalica, Ceratothoaoestroides, and Ceratothoaverrucosa, further resolving taxonomic uncertainties within the genus.

Host-parasite relationships: Mothocya plagulophora parasitizing Hemiramphus far in the Southeast coast of India

Totally 384 Mothocya plagulophora were collected in the branchial cavities of Hemiramphus far from the Southeast coast of India during the study period (from July to September 2013). 204 parasites were found in the left branchial cavity and 180 in the right one. The maximum prevalence was observed in July 2013 and the minimum in September 2013. The intensity ranged from a minimum value (1.3) in July and August to a maximum (1.4) in September 2013. In most cases, the parasite was located between the second and the third branchial arch, attached either to the vomerine arch or to the internal wall of the branchial operculum.

Effect of the parasitic isopod, Catoessa boscii (Isopoda, Cymothoidae), a buccal cavity parasite of the marine fish, Carangoides malabaricus

OBJECTIVE

To examine the effect of isopod parasite Catoessa boscii (C. boscii) on Carangoides malabaricus (C. malabaricus).

METHODS

The host fish C. malabaricus infested by C. boscii were collected directly from the trawlers landed at Parangipettai coast during December 2008 to November 2009. Data regarding the total length, width, weight and sex of the host fish were recorded. Effect of infestation on C. malabaricus, the length and weight data were analysed and host specificity of isopods was also examined.

RESULTS

During the sampling period, 585 C. malabaricus were examined. Among them, 218 specimens were found to carry 243 parasites. Three pairs of isopods (one male with one female) were recorded from the host fish and each pair was attached to the tongue in the buccal cavity of the host. Another pair was also found where the male and male, female and female isopod had settled on the tongue in the buccal cavity. Gross lesions observed in the buccal cavity of infested fish showed small pin-holes in the tongue region, through which dactyls of pereopod's penetrating claws dig into the host tissues. The maximum weight loss was reported in females (5.43%) than in males (3.75%) of C. malabaricus. Due to infestation of different isopod parasites in both male and female fish, the effects on the length-weight relationship of C. malabaricus were compared. The rate of increased growth in weight in uninfested female fish was found to be higher than that of the infested. The weight gain is faster in uninfested fish than in the infested fish.

CONCLUSIONS

From the above mentioned observations, it is clear that the worst of fish on account of the infestation of isopods are the C. malabaricus succumbed to the attack of isopod parasites. Although, the infestation did not cause immediate death, it had affected the normal growth of the host fish.

A new record of parasitic isopod for the Indian fauna (Mothocya karobran Bruce, 1986) from Strongylura strongylura in the Pazhayar region, Southeast coast of India

Cymothoid isopods are permanent ectoparasites of fish. In the present study Strongylura strongylura captured in gillnets from the inshore waters of Pazhayar from January to March-12. Among the 122 Belonidae fishes examined, 16 specimens were parasitized by isopods belonging to the species Mothocya karobran, a new record of this cymothoid isopod for the first time from India. Lowest prevalence occurred in January (10.5 %) and the highest in February (15.9 %). The infected fishes usually carried one cymothoid per branchial cavity. 12 parasites were found in the left branchial cavity and 4 parasites in the right. The non ovigerous female (18.5-24.7 mm) and female ovigerous (20.8-27.4 mm) in total length.