Hydraena atlantica Perkins

Although Hydraena atlantica Perkins is known from New Brunswick and Nova Scotia within Atlantic Canada, it is not frequently seen or collected. The specimen illustrated in the photographs below was collected by Joyce and Francis Cook in a mixed forest along the Parry Road near Carleton, Yarmouth County, Nova Scotia, Canada on August 22, 1992. Using a car net in the evenings the Cooks have collected a considerable number of individuals at the above locale, along the Medway River and at Caledonia in Queens County, and on the Oak Park Rd. between East Pubnico and Barrington Passage. D.H. Webster has also found them near the Cornwallis River, Kentville, Kings County, NS.

Adults of this species are found along the margins of streams and ponds. Perkins (2001) points that they have a specialized "exocrene secretion delivery system" which increases the effectiveness of the respiratory bubble that they carry with them while under water. Their legs have specialized setae which spread these secretions along the margins of the body where the bubble is held. Thbeetles tip themselves from side to side while performing this "secretion grooming" while out of the water.

Adults and larvae are generalist feeders that graze on wet surfaces of stones, sand grains, and plant matter feeding on algae, bacteria, protozoans, decomposing particles, etc. (Perkins, 2001). Note the very elongate mandibular palps of this genus which project forward in an antenna-like fashion. The antennae themselves are rather small and the 5-segmented antennal club can be see in the ventral habitus photograph curled beneath the ventral margin of the eye.

Hydraena is a cosmopolitan genus with approximately 500 species described worldwide of which 29 species are found in North America. In New Brunswick and Newfoundland Hydraena angulicollis Notman has additionally been recorded while in NB Octhebius kaszabi Janssens, another member of the family Hydraenidae (the so-called "minute moss beetles"), has also been found. Perkins (1980) is the definitive treatment of this family.

dorsal habitus

ventral habitus

lateral habitus

References

Perkins, P.D. 1980. Aquatic beetles of the family Hydraenidae in the Western Hemisphere: classification, biogeography and inferred phylogeny (Insecta: Coleoptera). Quaestiones Entomologicae, 16: 3-554.

Perkins, P.D. 2001. Hydraenidae Mulsant, 1844. In Arnett, R. H. Jr. & Thomas, M. C. [ed.] American Beetles, Volume 1: Archostemata, Myxophaga, Adephaga, Polyphaga: Staphyliniformia. CRC Press, Boca Raton, USA. pp. 228-232.