Insights on the biology and ecology of the deep-water shrimp Parapontophilus occidentalis (Faxon, 1893) (Crustacea: Caridea: Crangonidae) in the eastern Pacific with notes on its morphology.

The deep-water crangonid Parapontophilus occidentalis (Faxon, 1893) is endemic to the eastern Pacific and has been reported from Mexico to Chile, in depths of 837-4082 m. Material collected off the west coast of the Baja California Peninsula (BCP) during the TALUD XV, XVI and XVI-B cruises consists of a series of 136 specimens (M:F = 1:3.6) with 30 % of ovigerous females. The material examined was captured in depths of 1296-2093 m. Size ranged from 8.4 to 16.1 mm CL, with females being significantly larger than males. Number of eggs carried by ovigerous females ranged from 7 to 998, without a significant relationship between female size and number of eggs. Using only data of females carrying at least 100 eggs, egg mass weight varied from 0.036 to 0.181 g. Size of oval-shaped eggs also varied considerably (0.515 to 0.922 mm). Larger densities of P. occidentalis were observed between 1700 and 2100 m, where larger individuals were collected, and sex proportions differed across all depth strata. At the northern BCP, P. occidentalis was collected at dissolved oxygen concentrations from 0.76 to 1.83 ml l(-1), at temperature from 2.1 to 3.4°C, and salinity from 34.54 to 34.63 kg g(-1). Density of P. occidentalis was positively correlated with dissolved oxygen, salinity, and silt contribution to sediments, and negatively correlated with temperature and primary productivity five months before sampling.

Systematic position of Neocrangon communis (Decapoda, Crangonidae) based on the features of larval morphology.

The present article deals with morphological comparison of four species of shrimp larvae, such as Neocrangon communis and Mesocrangon intermedia, Crangon dalli and C. septemspinosa, inhabiting the Okhotsk Sea and north-western part of the Pacific Ocean. Morphological comparison of I-V zoeal stages is discussed. The main morphological differences of the appropriate larval stages are detected. Most features of C. dalli and C. septemspinosa are similar and differ from M. intermedia and N. communis. It is shown that M. intermedia and N. communis more similar species by their origin than it is accepted to think. It is assumed that these two species should be included into one genus-Mesocrangon. The figures of I, III-V zoeal stages are presented.

Two new species and two new records of deep-water caridean shrimps from Brazil (Decapoda: Pandalidae, Palaemonidae, Crangonidae).

The present study deals with four species of benthic deep-water caridean shrimps collected on the continental slope off southeastern Brazil, between 360 m and 900 m. The deepwater pandalid Bitias stocki Fransen, 1990, previously known only from a few localities in the eastern Atlantic, is reported for the first time from the western Atlantic (Brazil). The Brazilian material of B. stocki also represents the first record of the genus Bitias Fransen, 1990 in the western Atlantic. The palaemonid Periclimenes tenellus (Smith, 1882), previously known only from South Carolina and New Jersey, USA, is reported for the first time from Brazil, representing a considerable range extension of this uncommon species into the southwestern Atlantic. Another deepwater palaemonid shrimp is described as new: Periclimenes bathyalis sp. nov. The new species is morphologically closest to the echinoid associates Periclimenes milleri Bruce, 1986 and Periclimenes ingressicolumbi Berggren & Svane, 1989. Finally, the bizarre deepwater crangonid genus Prionocrangon Wood-Mason in Wood-Mason & Alcock, 1891 is reported for the first time from Brazil and the southwestern Atlantic, where it is represented by a new species, Prionocrangon brasiliensis sp. nov.

Invasion success of Fibrillanosema crangonycis, n.sp., n.g.: a novel vertically transmitted microsporidian parasite from the invasive amphipod host Crangonyx pseudogracilis.

Parasitism is known to be an important factor in determining the success of biological invasions. Here we examine Crangonyx pseudogracilis, a North American amphipod invasive in the United Kingdom and describe a novel microsporidium, Fibrillanosema crangonycis n.sp., n.g. The primary site of infection is the female gonad and the parasite is transovarially transmitted to the eggs. PCR screening reveals a female bias in the distribution of parasites (96.6% of females, N=29; 22.2% of males, N=27), which is indicative of host sex ratio distortion. The morphological and molecular characterisations of this new microsporidium place it outside all currently established genera. On the basis of these differences, we erect the new genus Fibrillanosema n.g. While F. crangonycis is morphologically identical to uncharacterised microsporidia from populations of North American amphipods, it is distinct from microsporidia found in European populations of amphipods. These data support the hypothesis that vertically transmitted parasites may be selectively retained during invasion events. Furthermore where vertical transmission is combined with host sex ratio distortion these parasites may directly enhance host invasion success through increased rates of population growth.

Syncrangon, a new crangonid genus, with redescriptions of S. angusticauda (De Haan) and S. dentata (Balss) (Crustacea, Decapoda, Caridea) from East Asian waters.

A new genus of the crangonid shrimps, Syncrangon, is proposed for Crangon angusticauda De Haan, 1849 and C. (Sclerocrangon) angusticauda var. dentata Balss, 1914, both from East Asian waters. The new genus is readily distinguished from all known genera of the Crangonidae by the flattened middorsal carina and the deep groove on each lateral side of the middorsal carina on the third to sixth abdominal somites. Syncrangon angusticauda new combination has previously been assigned to the genus Metacrangon, while S. dentata new combination has not been reported since the original description. These two species are easily distinguished from each other by many characters, especially the rostral and abdominal features. They are redescribed and illustrated in detail.