Further steps of Cryptorchestia garbinii invasion in Polish inland waters with insights into its molecular diversity in Central and Western Europe

Cryptorchestia garbinii Ruffo, Tarocco and Latella, 2014 (Amphipoda: Talitridae), a semiterrestrial amphipod, reported (as Orchestia cavimana Heller, 1865) from the Polish inland waters, e.g., the lowermost Vistula River, for the first time in 2009. Now, we have reported this species from the upper Oder River, which is c.a. 350 km SE from the closest known localities near Berlin, Germany. We confirmed its identity by the DNA barcodes and showed that all individuals found so far in other countries in Central and Western Europe represent the same haplotype, excluding a singleton from the locus typicus of this species in Lake Garda, Italy.

Temporal variation in the shore amphipod community in the supralittoral zone of Bizerte Lagoon (northern Tunisia)

Seasonal variation in the structure of the amphipod community on the banks of Bizerte Lagoon was studied at Menzel Jmil (37°13′8″N 09°55′1″E) from July 2006 to June 2007. The distance between the actual sites of collection (sampling points) and the shoreline varied from 70 cm in September to 6.8 m in December. Specimens were mainly collected from under roots of Cymodocea nodosa and Suaeda maritima. In the laboratory, the specimens of Amphipoda (N = 10 645) were preserved in ethanol 70%, identified, sexed, and counted under a binocular microscope. Monthly counts varied between 553 (November) and 1240 individuals (April). Eight species of talitrids were identified, based on the specific characters of their gnathopods and pereiopods. Furthermore, the results show that the amphipod community of Bizerte Lagoon is primarily composed of 3 species, Orchestia mediterranea, Orchestia gammarellus and Orchestia montagui. The species last-mentioned represented the most frequent form in summer, whereas the other two, Orchestia mediterranea and Orchestia gammarellus, dominated in autumn. Orchestia stephenseni, Platorchestia platensis, Talorchestia deshayesii, Talitrus saltator, and Orchestia cavimana, were also found. A subsequent analysis of various diversity parameters of the amphipod community indicated a seasonal variation in abundance, species richness, and diversity.

Distribution of the Ponto-Caspian Amphipods in Turkish Fresh Waters: An Overview

To date, 13 amphipod species [Dikerogammarus haemobaphes(Eichwald, 1841); D. istanbulensis Özbek & Özkan, 2011; D. gruberi Mateus & Mateus, 1990; Echinogammarus ischnusStebbing, 1899; Pontogammarus robustoides (Sars, 1894); P. maeoticus(Sowinsky, 1894); P. aestuarius(Derzhavin, 1924); Obesogammarus turcarum Stock, 1974; Amathillina cristata Sars, 1894; Chelicorophium curvispinum Sars, 1895; C. maeoticum(Sowinsky, 1898); C. robustum Sars, 1895 and Orchestia cavimana Heller, 1865] were reported from Turkey as the representatives of Ponto-Caspian amphipod fauna. Previous records and current distributional patterns of Ponto-Caspian amphipod crustaceans in Turkish inland waters were investigated. Three new localities were revealed as one of the southernmost points in distributional area of Pontogammarus robustoides (Sars, 1894).

The clonal composition of biramous and uniramous arthropod limbs

We present the first comparative cell lineage analysis of uniramous and biramous limbs of an arthropod, the crustacean Orchestia cavimana . Via single cell labelling of the cells that are involved in limb development, we are able to present the first complete clonal composition of an arthropod limb. We show that the two main branches of crustacean limbs, exopod and endopod, are formed by a secondary subdivision of the growth zone of the main limb axis. Additional limb outgrowths such as exites result from the establishment of new axes. In contrast to general belief, uniramous limbs in Orchestia are not formed by the loss of the exopod but by suppression of the split into exopod and endopod. Our results offer a developmental approach to discriminate between the different kinds of branches of arthropod appendages. This leads to the conclusion that a ‘true’ biramous limb comprising an endopod and an exopod might have occurred much later in euarthropod evolution than has previously been thought, probably either in the lineage of the Mandibulata or that of the Tetraconata.