DNA barcodes combined with geometric morphometry challenge species hypothesis in palaemonid shrimp

Although the Mediterranean Region is known as a hotspot for biodiversity and endemism its freshwater fauna is still greatly unexplored, and even the emblematic taxa such as decapods require in-depth integrative investigation. In our research we used integrative approach composed of various geometric morphometric and molecular methods to challenge the taxonomic status of two freshwater shrimps representing Palaemonidae: Palaemon antennarius and Palaemon minos. Basing on 352 COI sequences, three Molecular Operational Taxonomic Units (MOTUs) were defined. Two of them belonged to P. antennarius: first inhabiting Apennine Peninsula and Sicily, the second one from the Balkan Peninsula. The third MOTU corresponded to Palaemon minos from Crete. The Balkan MOTU of P. antennarius was closer to P. minos in terms of genetics, than to the other conspecific MOTU. The carapace shape variation, studied on 180 individuals, was mainly explained by the geographic distribution. Balkan and Cretan groups were clearly distinguished, while other samples were distributed along the shape gradient from Sicily and southern Apennine Peninsula to the Balkans. The results of our study showed that, either the MOTU assigned to the Apennine Peninsula and Sicily constitutes a separate species or, alternatively, P. minos should be synonymised with P. antennarius.

Deep into darkness: the first stygobitic species of freshwater shrimp of the genus Caridina (Crustacea: Decapoda: Atyidae) from Northern Vietnam

The first stygobitic species of atyid freshwater shrimps from Vietnam is described from Cuc Phuong National Park, Northern Vietnam. Caridina thachlam sp. nov. can be distinguished from its congeners by a suite of morphological characters such as strongly reduced eyes without eyestalk, short and almost unarmed rostrum and slender pereiopods. Molecular phylogenetic data from the mitochondrial cytochrome oxidase subunit I (COI) and 16S ribosomal RNA genes also support the distinctiveness of the new species from all other species that we have examined.

Solomon’s Gold Mine: Description or redescription of 24 species of Caridina (Crustacea: Decapoda: Atyidae) freshwater shrimps from the Solomon Islands, including 11 new species.

Following recent (2014–2017) collections made in the Solomon Islands by the MNHN and the NGO ESSI, we provide a checklist of the species of amphidromous freshwater shrimps of the genus Caridina H. Milne Edwards, 1837 from this region. Using morphological as well as molecular data in an integrative taxonomic perspective, we found a total of 24 species, including 11 new for science, that are described or re-described, illustrated and discussed in relation to their habitat and distribution. Newly described species are Caridina barakoma sp. nov., C. choiseul sp. nov., C. intermedia sp. nov., C. maeana sp. nov., C. nana sp. nov., C. piokerai sp. nov., C. pisuku sp. nov., C. paratypus sp. nov., C. poarae sp. nov., C. sikipozo sp. nov. and C. turipi sp. nov. Caridina gueryi Marquet, Keith & Kalfatak, 2009 is re-validated as a species distinct from C. buehleri Roux, 1934. Lectotypes are designated for C. mertoni Roux, 1911 and C. papuana Nobili, 1905. Diagnoses for 6 informative species groups are provided: C. brevicarpalis group, C. gracilirostris group, C. nilotica group, C. typus group, C. serratirostris group and C. weberi group. A map of the species distribution in the Solomon Islands, as well as the phylogenetic relationships between the species and their relatives, are provided.

Do hydroelectric dams affect the abundance and population structure of freshwater shrimps?

Freshwater shrimps play an important role in many ecological processes since they are epibenthic detritivores but also prey on other invertebrates and are predated by fishes. The knowledge about their biology allow the development of management strategies to improve the use of natural resources by avoiding overfishing and enhancing productivity. Here we evaluated the population structure of the shrimp Macrobrachium amazonicum in the river Rio Grande, upstream of the Água Vermelha hydroelectric dam. They were captured monthly from October 2017 until March 2018, in six sites along the river. The first site was ∿1000 m distant from the dam and the sixth was ∿4000 m distant. A sac-like sieve and traps were used to capture the shrimps. The sieve was dragged three times for 180o. The traps were left by the river margins for six hours. In the laboratory, the shrimps were sexed and measured (carapace length; CL). In total, 6455 individuals were captured: 4499 females (294 breeding), 1445 males, and 217 juveniles. Female mean size was 7.50 ± 3.47 mm, male mean size was 7.44 ± 2.40 mm, and juvenile mean size was 3.24 ± 1.10 mm. The smallest individual was found in site III and it was a juvenile of 1.08 mm. The largest had 20 mm and was found in site II. The smallest breeding female had 3.8 mm CL. The largest individuals were more abundant in the sites near the dam, whereas the smallest were more abundant in the farthest sites. The highest abundance was seen in sites III and IV, and the lowest, in site VI. Unlike males and juveniles, females (both breeding and non-breeding) were more abundant (Anova, p < 0.01) near the dam. By knowing the population structure of M. amazonicum it is possible to understand how they are being affected by the environmental changes caused by the hydroelectric dam

Taxonomic study of the freshwater shrimps genus Atyoida Randall, 1840 (Crustacea: Decapoda: Atyidae) in Polynesia with a revalidation of A. tahitensis Stimpson, 1860

Numerous specimens of Atyoida were collected in Polynesia during specific samplings led by the Muséum national d’Histoire naturelle (MNHN, Paris) from 1983 to 2017. In the context of an integrative taxonomy, all the Polynesian specimens were morphologically and genetically studied. The molecular study proved that the specimens were split in two different clades separated by 7% genetic distance (16S) and geographically structured that can be considered as two distinct species. In this article, A. tahitensis Stimpson, 1860 from Eastern Polynesia is re-validated as a distinct species from A. pilipes (Newport 1847) from Vanuatu to Marquesas archipelago. The morphological study, besides coloration patterns (Body blackish on its back, ornamented on its flanks with numerous bluish dots and longitudinal stripes for A. tahitensis; orange-yellow back as well as the antennular peduncle, telson and uropods with the flanks whitish ornamented with numerous blue-black patterns of various shapes for A. pilipes), did not allow us to find characters to distinguish easily the two species. Detailed re-descriptions and the geographical distribution of these two species are given and a neotype deposited in the MNHN (Paris) is designated for A. tahitensis.

Bioproductivity of ponds of VI fish breeding zone

The paper highlights the prospects of cultivating heat-loving species, such as Australian crayfish and freshwater shrimps in the VI fish breeding zone. Australian crayfish and freshwater shrimps breeding is considered economically attractive for entrepreneurs, having a limited area for farming facilities. At the same time, pond ecosystems require the individual approach and close study in terms of the environmental conditions for the cultivated species upkeeping and the natural forage base that determine the pond biological productivity. Today, there are no clear recommendations on the summer keeping warmwater aquaculture species, in particular, Australian crayfish and freshwater shrimp in the Astrakhan region. To cultivate the new objects of warmwater aquaculture in 2017-2019 the small innovative enterprise Modern Sharapovskiy Fish Breeding Complex researched the production potential of ponds of various categories for receiving marketable products; there was studied the forage base, biomass of zooplankton and zoobenthos satisfying the nutritional needs of farmed objects. As a result of experimental work, it was found that in pond No.2, where freshwater shrimps were grown, there were registered 5 species of Cladocera and 1species of Rotifera, while in pond No.1 used for breeding Australian crayfish there were registered 4 species of Rotifera and only 1 species of Cladocera. Presumably, the observed species composition of the studied ponds is specified by the selectivity of the cultivated objects in zooplankton consumption. The possibility of increasing the bio-productivity of ponds by alternate growing aquaculture and agricultural products has been considered.