A new redescription of Daphnia pusilla (Serventy, 1929) (Cladocera: Daphniidae) with emphasis on the thoracic limbs of Daphnia (Ctenodaphnia) Dybowski amp; Grochowski, 1895.

The genus Daphnia O.F. Mller, 1776 (Crustacea: Cladocera) still has a confused taxonomy for several objective and subjective reasons. Still there are many taxa with inadequately described morphology, primarily among the subgenus Daphnia (Ctenodaphnia) Dybowski Grochowski, 1895. We provide a redescription of an Australian endemic taxon Daphnia (Ctenodaphnia) pusilla (Serventy, 1929) according to recent standards of morphological study with special attention to the thoracic limbs. We conclude that main differences between thoracic limbs of the subgenera D. (Ctenodaphnia) and Daphnia s. str. concern the limb I only as it is well-known among the cladocerans of other families. But still only a few species of D. (Ctenodaphnia) have been studied adequately, and efforts to redescribe their morphology need to be continued.

Complete mitochondrial genomes of two marine monogonont rotifer Brachionus manjavacas strains.

The complete mitochondrial genomes of Brachionus manjavacas German strain were 10,721 bp (mitochondrial DNA I) and 12,274 bp (mitochondrial DNA II) in size, while the complete mitochondrial genomes of B. manjavacas Australian strain were 10,889 bp (mitochondrial DNA I) and 12,443 bp (mitochondrial DNA II) in size. Of 12 protein-coding genes (PCGs), 99.6% of amino acid sequences were identical between the two strains. Of 12 PCGs of both B. manjavacas strains, three genes (ND1, ATP6, and ND5) had incomplete stop codon T. Furthermore, ATA was the start codon for ND4, ND5, and CO3 genes, whereas that for other PCGs was ATG in both strains. The base compositions of 12 PCGs in the B. manjavacas strains were similar, indicating that the mitochondrial genome of the two strains was structurally conserved over evolution. The gene structure and its orientation of 12 PGCs of B. manjavacas strains were identical, as shown in other marine Brachionus rotifers and the freshwater Brachionus rotifers, while the freshwater rotifer B. calyciflorus had an additional cytochrome b gene in the mitochondrial DNA I.

Invasion of a Holarctic planktonic cladoceran Daphnia galeata Sars (Crustacea: Cladocera) in the Lower Lakes of South Australia.

We found a Holarctic microcrustacean Daphnia galeata Sars, 1863 (Cladocera: Daphniidae) in the Lower Lakes of South Australia. This taxon was never detected in continental Australia before. Its identity was confirmed by the sequences of mitochondrial COI, 12S and 16S and nuclear 18S and 28S genes. A maximum likelihood tree from a dataset from combining 12S + 16S mitochondrial sequence and a split network of the COI haplotypes are provided, but resolution of both genes is not sufficient to reveal the exact region of the Holarctic from where D. galeata was introduced to Australia; the vector of its invasion also is unknown. We hypothesize that appearance of D. galeata in the Lower Lakes of the Murray River is related to a recent anthropogenic eutrophication of water bodies in this region, keeping in mind that examples of successful invasion of some European lakes by D. galeata after their eutrophication are well-known. We also hypothesize that establishment of this non-indigenous taxon populations in Australia might have a strong negative impact on native lake biota.