Hydrochus brevitarsis Knish

The specimen of Hydrochus brevitarsis Knish pictured below was collected in a vernal pool near the Cornwallis River, Kentville, Kings County, Nova Scotia, Canada on April 21, 2004 by D. H. Webster. It is the first record of this very rare species in Atlantic Canada. H. brevitarsis closely resembles the recently described and even more rare H. spangleri Hellman (Steiner et al. 2003). H. spangleri appears to be found solely in such vernal pools and is known from only five of them in Talbot County, Maryland, USA.

Smetana (1988) gives only two locations for H. brevitarsis in Canada (near Montreal, QC and near Trenton, ON) and mentions that in the USA it is found further west to Michigan and Minnesota. Thus the discovery of this species in Nova Scotia is a significant range extension for this very seldom seen species.

In Atlantic Canada Hydrochus squamifer LeConte has also been found in both New Brunswick and Nova Scotia while Hydrochus pseudosquamifer Miller has been recorded in Nova Scotia. Both of these latter two species are more frequently encountered than H. brevitarsis.

In Maryland Steiner et al. (2003) note that H. spangleri is restricted to forest vernal pools where flooding occurs primarily through water-table mounding and groundwater inflow. The forest canopy in these areas consists of trees such as red maple, beech, white oak, sweetgum, and willows. Most specimens have been collected in the spring between March 1 and June 8. Although the beetles have functional wings they have not been observed to fly and have not been collected in light traps. Smetana (1988) notes that in Canada H. brevitarsis has previously been found in leaf litter and moss in a calcareous bog.

dorsal habitus

ventral habitus

lateral habitus

References

Smetana, A. 1988. Review of the family Hydrophilidae of Canada and Alaska (Coleoptera). Memoirs of the Entomological Society of Canada, 142. 316 pp.

Steiner, W.E., Staines, C.L., McCann, J.M., and Hellman, J.L. 2003. The Seth Forest Water Scavenger Beetle, a new species of Hydrochus (Coleoptera: Hydrophiloidea: Hydrochidae) from the Chesapeake-Delmarva Region. Coleopterists Bulletin, 57(4): 433-443.