Aquarius najas explained

Aquarius najas, also known as the river skater,^[1] is a European species of water strider.^[2] It was formerly known as Gerris najas, but the subgenus Aquarius was elevated to generic rank in 1990 on the basis of phylogenetic analysis.^{[3] [4]}

Habitat

This species generally require moving waters, living in places like the stony margins of rivers.^[5]

Appearance

Aquarius najas is among the largest species of water striders, as typical of members of the genus Aquarius (including another European species, the on average marginally smaller A. paludum). Adult females of A. najas average 16.5mm long and males about 30% smaller.^[6] In northern Europe it is wingless, but in central and southern Europe it often has wings.^[2]

Behaviour

Aquarius najas spend the winter as adults. In the spring, they form pairs, and before mating, row about together on the surface during the daytime. At night, they separate, and the females lay their eggs beneath the water in closely packed patches. Normally the eggs are laid on the surface of flat stones. Males may guard females after copulation to prevent other males from competing. It has been claimed that males may remain paired with females for several weeks.^[7]

External links

• Image
• Female territoriality in the waterstriders Gerris najas and G. cinereus

Notes and References

1. Web site: Aquarius najas (River skater) (Gerris najas) . Pir.uniprot.org . 2011-08-29.
2. Ahlroth . Alatalo . Hyvärinen . Suhonen . 1999 . Geographical variation in wing polymorphism of the waterstrider Aquarius najas (Heteroptera, Gerridae) . Journal of Evolutionary Biology . 12 . 1 . 156–160 . 10.1046/j.1420-9101.1999.00022.x . 83872458 .
3. Andersen, Nils Møller. 1990. Phylogeny and taxonomy of water striders, genus Aquarius Schellenberg (Insecta, Hemiptera, Gerridae), with a new species from Australia. Steenstrupia. 16. 4. 37 - 81. Abstract
4. Gallant, Sharon L. . Fairbairn, Daphne J.. 1996. A New Species of Aquarius from the Southeastern United States, with Electrophoretic Analysis of the Clade Containing Gerris, Limnoporus, and Aquarius (Hemiptera: Gerridae). Annals of the Entomological Society of America. 89. 5. 637 - 644. 10.1093/aesa/89.5.637. Abstract
5. Brinkhurst, R. O. (1966) "Population dynamics of the large pond-skater Gerris najas Degeer (Hemiptera-Heteroptera)." The Journal of Animal Ecology Vol. 35, No. 1 : 13-25. Abstract
6. Andersen, N.M. . 1997 . A phylogenetic analysis of the evolution of sexual dimorphism and mating systems in water striders (Hemiptera: Gerridae) . Biological Journal of the Linnean Society . 61 . 3 . 345–368 . 10.1006/bijl.1996.0130 . free .
7. Campbell. Veronique. Fairbairn. Daphne J.. 2001. Prolonged copulation and the internal dynamics of sperm transfer in the water strider Aquarius remigis. Canadian Journal of Zoology. 79. 10. 1801–1812. 10.1139/cjz-79-10-1801. 1480-3283.