On three new species of Mesochra Boeck, 1865 (Harpacticoida: Canthocamptidae) from Iceland

Three new species of Mesochra Boeck, 1865, were found during two surveys in south‐western Iceland of the feeding ecology of juvenile lumpsucker Cyclopterus lumpus Linnaeus, 1758, in floating seaweed and the seasonality of harpacticoids in a low intertidal pool. Only two species of the genus, M. lilljeborgi Boeck, 1864 and M. rapiens (Schmeil, 1894), have been found in previous studies in Iceland. The three new species, Mesochra ingolfssoni sp. nov., Mesochra snoppa sp. nov., and Mesochra freyri sp. nov. resemble M. stellfeldi Jakobi, 1954 in the normal (not dwarfed) outer seta of both male and female P5 EXP, but differ in that M. stellfeldi possesses unequal inner baseoendopodal setae on the female P5. The three new species resemble M. pygmaea (Claus, 1863) in the equal inner baseoendopodal setae of the female P5, but differ in the dwarfed outer seta of the male and female P5 EXP present in M. pygmaea, and can be easily separated by shape of the rostrum, female P6, number of pinnate elements on the second antennular segment, general shape of the antenna and shape of the lateral and distal inner spines, among other character states.     

Social behaviour in a thrips from Panama

Summary

Anactinothrips gustaviae is an advanced parasocial thrips (Thysanoptera: Phlaeothripidae: Idolothripinae) from Panama which lives in colonies on smooth-barked trees, reproduces communally, cooperatively broods young, and forages in a highly coordinated fashion (with young, if present). Although this species is presumably haplodiploid, we argue that the patchy, but intergenerationally stable, food supply is the primary factor which has promoted the evolution of advanced social behaviours in this species as opposed to most other thrips.     

Copepodid stages of laboratory-reared Astericola asterinae (Bocquet, 1952) (Copepoda,Poecilostomatoida, Lichomolgidae), a copepod associated with Asterina gibbosa (Pennant, 1777) of Lake Faro (Messina)

We describe the five copepodids of Astericola asterinae (Bocquet, 1952) a poecilostomatoid copepod (family Lichomolgidae), reared in the laboratory. It shows only very slight sexual dimorphism in the third segment of C5 maxilliped. Our study of the copepodid development, together with the observations of Carton (1964), Bocquet et al. (1970) and Conradi et al. (1993), support the separation of A. asterinae from its sister species A. clausi (Rosoll, 1889).     

Paranannopidae (Copepoda: Harpacticoida) from sublittoral soft sediments in Spitsbergen

Based on specimens of Paranannopidae collected from 30 to 123 m depth in Sassenfjord, Spitsbergen, two species of Paradanielssenia Soyer, 1970 (P. christineae sp. nov. and P. kathleenae sp. nov.) are described. These can be distinguished from known species by differences in the number of claviform aesthetascs on the mouthparts and in the arrangement or form of setae on the legs. A key to species of Paradanielssenia is provided. Mucrosenia gen. nov. (type species M. kendalli sp. nov.) is established on the basis of a single female and can be distinguished from all known paranannopid genera by the structure of the caudal ramus and the P2 endopod-2 which has no inner seta and a large mucroniform process at the outer distal corner. Psammis kliei Smirnov, 1946 is assigned to this genus as species incertae sedis. Danielssenia quadriseta Gee, 1988 is recorded for the first time outside its type locality in Oslofjord. Danielssenia spitsbergensis sp. nov. is described from a single male specimen and can easily be distinguished from other known species by the presence of only two outer spines on exopod-3 of P3-4. However, because of differences in the structure of the P2 endopod and P5, the species is placed incertae sedis within Danielssenia pending the discovery of the female.     

Poecilostomatoid Copepods from an Intertidal Mud Flat in the Yellow Sea

Thirteen new species and one new genus of poecilostomatoid copepods are described from intertidal mud flats in the central west coast of the Korean Peninsula facing the Yellow Sea. Nine species are found in association with invertebrates: Hemicyclops ventriplanus n. sp. from the decapod crustacean Upogebia major (De Haan); Clausia lobata n. sp. from the polychaete Marphysa sanguinea (Montagu); Presynaptiphilus minutus n. sp. from the ophiuroid Amphiura sinicola (Matsumoto); Synaptiphilus longicaudus n. sp. and Enterophilus cercomegalus n. gen. et n. sp. from the holothurian Protankyra bidentata (Woodward and Barrett); Goidelia pelliviva n. sp. from an echiuroid Thalassema sp.; Lichomolgus bullatus n. sp. from the bivalve Striarca (Didimacar) tenebrica (Reeve); Critomolgus nudus n. sp. from the pennatulacean Virgularia gustaviana (Herklots); and Notoxynus tertius n. sp. from the sea anemone Cerianthus filiformis Carlgren. The other four species are found in stagnant water on the mud flat: Kelleria vaga n. sp., Macrochiron anormalum n. sp., Pseudomacrochiron urostenum n. sp. and Pseudanthessius dentatus n. sp.     

Copepods of the genus Colobomatus (Poecilostomatoida: Philichthyidae) from fishes of the family Sillaginidae (Teleostei: Perciformes)

Six species of Colobomatus, five of which are new to science, were found in a survey of 26 species of sillaginid fishes in the Indo-west Pacific. Three of the species are closely related and occur in the head cavities of various species of their hosts. Colobomatus sillaginis West, 1983 is recorded in Sillaginodes punctata and 12 species of Sillago, from around the coast of Australia and in the Gulf of Thailand, representing many new host and locality records. Female C. asiaticus sp. nov. are described from southeast Asia and the Persian Gulf, in three species of Sillago. Female C. arabicus sp. nov. are described from two species of Sillago occurring only in the Persian Gulf. A second intrageneric grouping of three species of Colobomatus inhabits a different microhabitat: tubes of the lateral line scales. Each of these species infects several sillaginid fishes, and in contrast to members of the first species-group they are entirely allopatric with each other. In Australia, female C. fulloonae sp. nov. are described from three species of Sillago in northern waters, and female C. charleah sp. nov. are described from two species of Sillago and Sillaginodes punctata in southern waters. Female C. westi sp. nov. are described from three species of Sillago in the waters of eastern Asia (Japan, Korea and China). Only one male specimen of each of C. arabicus sp. nov., C. charleah sp. nov. and C. westi sp. nov. was found.     

Three new species of the genus Normanella Brady (Copepoda: Harpacticoida) from the Gulf of Mexico

Three new species of Normanellidae are described from the Texas coast, Gulf of Mexico. Normanella texana sp. nov. has limited areolated patterns on the cephalothorax, short P5 exopod and endopod, short caudal ramus and short caudal seta VI-V. Normanella brevispina sp. nov. is characterized by its relatively long caudal rami, and areolated rostrum. Normanella chanhoi sp. nov. has well-developed areolated patterns on the cephalothorax, six-segmented antennule and a smooth apical margin of the rostrum. N. texana belongs to the bolini -lineage, and N. brevispina to the minuta -lineage. Normanella chanhoi establishes a new lineage of its own.     

Survival and reproduction of the mussel Xenostrobus securis (Lamarck) (Mollusca; Bivalvia; Mytilidae) in a Western Australian estuary. Pt. II: Reproduction,growth and longevity

Summary

Growth, longevity and breeding characteristics of populations of the mussel Xenostrobus securis in the Swan Estuary are remarkably variable, both between one year and another and between upstream and downstream localities. These characteristics and their variability may be accounted for by the species' physiological responses and limitations to variable salinity conditions. The Swan Estuary is subject to extreme temporal and spatial variations in salinity. Temperature has only a secondary significance on the biology of the mussel in this estuary.

Activity including growth is inhibited at chlorinities below 2‰. This occurs each winter during the discharge period. At Crawley (downstream) the discharge period rarely lasts more than a few weeks in mid winter, but at upstream limits of the estuary (e.g. Barker Bridge) it is highly variable and may last as long as seven months. Consequently the period of no-growth which corresponds to the discharge period varies between downstream and upstream populations and the total annual growth increment varies accordingly. Similarly the duration of the no-growth period and the total annual growth increment varies from year to year at upstream localities.

At Crawley mussels live only one year. At that locality there is almost total mortality of adults soon after spawning. The relationship of the post-reproductive mortality to intensity of reproductive effort is discussed. At Barker Bridge heavy post-reproductive mortality was not observed and animals may live two years or more. This greater longevity at Barker Bridge is considered to have survival advantage for the population which is living in an unstable and inconsistent environment. Downstream conditions are more seasonally regular and the populations there can rely on having optimal conditions each year.

Spawning begins at the downstream end of the estuary in November or December when the chlorinity rises to the critical lower limit for larval development (8 to 9‰. Cl). A wave of spawning moves up the estuary as the summer progresses, following the zone of optimal salinity conditions. It does not reach Barker Bridge until February or March. In 1964 the chlorinity did not reach the lower limit for larval development at Barker Bridge and no spawning or spatfall occurred there.

It is considered that X. securis is physiologically well adapted for persistence in an estuarine environment characterized by variable and unstable salinity conditions.     

Composition,characteristics and long-term variability of the freshwater microcrustacean fauna of the Faroe Islands

ABSTRACT

Despite the accessibility of the Faroe Islands, faunistic research on their numerous lakes and ponds is quite rare. The biota of Faroese freshwaters is still underexplored, and its specific traits raise many questions. In the present survey, 32 microcrustacean species were observed, 8 of which were new to the Faroese fauna. The obtained species list shows that Cladocera species prevail over Copepoda here, which is not typical of northern territories. This fact is due to (1) the extraordinarily warm climate of the Faroe Islands compared to other areas at similar latitudes because of the heating effect of the surrounding North Atlantic Current and (2) the lack of calanoid species, which have never been found in the freshwaters of the Faroe Islands. The diachronic analysis of the species diversity and composition over the centuries of research on the archipelago showed no evidence of the impact of global climate change on the fauna.