A new species of Acartia (Copepoda, Calanoida) from the Philippines, based on morphological and molecular analyses.

A new species of Acartia (Odontacartia), A. (O.) edentatasp. n., was collected from Leyte Island in the Philippines. Morphologically, the new species resembles A. (O.) pacifica Steuer, 1915. The female of the new species differs from other species of the A. (O.) erythraea Giesbrecht, 1889 species group in the absence of a pair of sharp spines on the posterior border of the genital double-somite and absence of setules on the lateral margins of urosomites 1-3. Unlike other congeners of the species group, males of the new species lack fine setules along the posterior margin of the prosome. Comparison of the new species with A. (O.) pacifica by pairwise distance data for the 16S (282 bp) gene indicates that these species differ by 20-21%, while the COI gene (636 bp) indicates a difference of 16-17%. The new species seems to be a coastal, occurring in warm waters having a salinity of 33.5.

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 of association of copepods with highly venomous box jellyfish Chironex, with description of new species of Paramacrochiron (Cyclopoida: Macrochironidae).

Paramacrochiron chironecicola n. sp. (Copepoda: Cyclopoida: Macrochironidae) is described from the highly venomous box jellyfish Chironex sp. collected from Malampaya Sound, Palawan Island, The Philippines. This is the first record of copepods associated with cubozoan medusae, although other cnidarian groups such scyphozoans, hydrozoans, and anthozoans are common hosts for symbiotic copepods. The infection sites were on the subumbrella, pedalium, and rhopalium, but also rarely on the adradial furrow. The new species is distinguished from other congeners by a combination of the following features: (1) the fifth pedigerous somite dorsally covering the anterior part of the female genital double-somite; (2) the fine structures of the antenna (relative lengths of segments) and maxilliped (positions of terminal elements) of the female; (3) the relatively long outer spines on the exopodal segments of legs 1-4; (4) the relatively long and thick female leg 5 bearing a long protopodal seta which reaches to the distal margin of the exopod; (5) the relatively short caudal ramus in the female; and (6) the plump prosome and short urosome in the male. Since members of the genus typically parasitize scyphozoans, especially rhizostomes, the association of this parasitic copepod on cubozoans may reflect the relatively close phylogenetic relationship between cubozoans and scyphozoans.

Fatty acids in six small pelagic fish species and their crustacean prey from the mindanao sea, southern Philippines.

Fatty acids are important in human health and useful in the analysis of the marine food web, however information on tropical pelagic organisms is scarce. Six zooplanktivorous small pelagic fish species (Decapterus kurroides, Decapterus macarellus, Selar crumenophthalmus, Sardinella lemuru, Spratilloides gracilis and Stolephorus insularis) and four of their zooplanktonic crustacean prey [three sergestoid species (Acetes erythraeus, Acetes intermedius and Lucifer penicillifer) and one calanoid copepod (Acartia erythraea)] were collected from the Mindanao Sea, and their fatty acids were profiled. The resulting profiles revealed 17 fatty acids that were specific to certain species and 9 {myristic acid [C14:0], palmitic acid [C16:0], stearic acid [C18:0]; palmitoleic acid [C16:1], oleic acid [C18:1n9c], linoleic acid [C18:2n6c], linolenic acid [C18:3n3], eicosapentaenoic acid (EPA) [C20:5n3] and docosahexaenoic acid (DHA) [C22:6n3]} that were common to all species. Cluster analysis and non-metric multidimensional scaling (NMDS) of fatty acids indicate a high similarity in profiles in all species, but separate fish and zooplankton clusters were obtained. Mackerel species (D. macarellus, D. kurroides and S. crumenophthalmus) had concentrations of total n-3 fatty acids that match those of their Acetes prey. The copepod A. erythraea and the sergestoid L. penicillifer exhibited the lowest values of the EPA:DHA ratio, which was most likely due to their phytoplanktivorous feeding habits, but the occurrence of the highest values of the ratio in Acetes suggests the inclusion of plant detritus in their diet. DHA values appear to affirm the trophic link among copepod, Lucifer, Acetes and mackerel species.

Differential chemosensory feeding behaviour by three co-occurring mysids (Crustacea, Mysidacea) from southeastern Tasmania.

Three mysid species showed differences in chemosensory feeding as judged from stereotyped food capturing responses to dissolved mixtures of feeding stimulant (either betaine-HCl or glycine) and suppressant (ammonium). The strongest responses were to 50:50 mixtures of both betaine-ammonium and glycine-ammonium solutions. In general, the response curve to the different mixtures tested was bell-shaped. Anisomysis mixta australis only showed the normal curve in response to the glycine-ammonium mixture. The platykurtic curve for Tenagomysis tasmaniae suggests a less optimal response to the betaine-HCl-ammonium solution. Paramesopodopsis rufa reacted more strongly to the betaine-ammonium than to the glycine-ammonium solutions, and more individuals of this species responded to both solutions than the other two species. It is suggested that these contrasting chemosensitivities of the three coexisting mysid species serve as a means of partitioning the feeding niche.