• Genes and Genomics
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• v.40 no.11
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• pp.1169-1180
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• 2018

Cave shrimps from the genera Typhlatya, Stygiocaris and Typhlopatsa (TST complex) comprises twenty cave-adapted taxa, which mainly occur in the anchialine environment. Anchialine habitats may undergo drastic environmental fluctuations, including spatial and temporal changes in salinity, temperature, and dissolved oxygen content. Previous studies of crustaceans from anchialine caves suggest that they have possessed morphological, behavioral, and physiological adaptations to cope with the extreme conditions, similar to other cave-dwelling crustaceans. However, the genetic basis has not been thoroughly explored in crustaceans from anchialine habitats, which can experience hypoxic regimes. To test whether the TST shrimp-complex hypoxia adaptations matched adaptive evolution of mitochondrial OXPHOS genes. The 13 OXPHOS genes from mitochondrial genomes of 98 shrimps and 1 outgroup were examined. For each of these genes was investigated and compared to orthologous sequences using both gene (i.e. branch-site and Datamonkey) and protein (i.e. TreeSAAP) level approaches. Positive selection was detected in 11 of the 13 candidate genes, and the radical amino acid changes sites scattered throughout the entire TST complex phylogeny. Additionally, a series of parallel/convergent amino acid substitutions were identified in mitochondrial OXPHOS genes of TST complex shrimps, which reflect functional convergence or similar genetic mechanisms of cave adaptation. The extensive occurrence of positive selection is suggestive of their essential role in adaptation to hypoxic anchialine environment, and further implying that TST complex shrimps might have acquired a finely capacity for energy metabolism. These results provided some new insights into the genetic basis of anchialine hypoxia adaptation.

• Animal cells and systems
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• v.16 no.1
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• pp.57-68
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• 2012

Two new harpacticoid species belonging to the genera $Microarthridion$ Lang, 1944 (Tachidiidae) and $Nitocra$ Boeck, 1864 (Ameiridae) are recorded from underground caves in the karst area of Ninh Binh Province, North Vietnam. $Microarthridion$ $thanhi$ n. sp. is distinguished from congeneric species by the number of setae on the antennary exopod, the structure of leg 5 in both sexes, and the finger-like process modified from an outer distal pinnate seta of the third endopodal segment of leg 2 in the male. $Nitocra$ $vietnamensis$ n. sp. has the character combination of six setae on the ellipsoidal exopod of leg 5 in both sexes, the first endopodal segment of leg 1 shorter than the whole exopod, the seta/spine armature of an inner seta of P2-P4 enp-1 and four elements on P2 enp-3, and the reduction of the proximal endite to a seta on the maxillary syncoxa.