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J. Entomol. Soc. Brit.Columbia 101,December2004 147 SCIENTIFIC NOTE New waterboatmen records for Western Canada (Hemiptera: Corixidae) R.D. KENNER^ and K.M. NEEDHAM^ — ABSTRACT Trichocorixa verticalis (Fieber) is reported for the first time from the mainland of British Columbia and the subspecific assignment is discussed. Based on specimens in the Spencer Entomological Museum, oneprovincial recordand one territo- rial recordare addedto the recent checklist ofCanadianHemiptera. During recent collecting trips in the coastal end to a second ditch that runs par- Lower Mainland of British Columbia allel to andjust inland ofthe coastal dike. (BC), Canada, we found a population (both In the October survey, semi-quantitative immatures and adults) of Trichocorixa data were collected between 1.3 km and verticalis (Fieber). Previously, T. verticalis 3.7 km inland from the dike. The density was known in BC only from three island of T. verticalis was found to drop sharply localities: two on Vancouver Island and beyond 1.8 km and no specimens were one on Thetis Island (Scudder 1977). A collected more than 2.2 km from the dike. fourth island record can be added to these: In May, we extended the surveyed area to Prevost Island, salt marsh pond, the coastal dike; T. verticalis was found at 10.vii.l986, J.D. Reynolds, 1 male, 2 fe- all sites between 0 and 1.3 km inland. males. SpencerEntomological Museum. While the assignment of the Delta Outside of BC, Trichocorixa verticalis specimens to T. verticalis was straightfor- has a widespread distribution. Two subspe- ward, the subspecific assignment was not. cies occur on each of the east and west In his key to subspecies of T. verticalis. coasts of North America with a fifth sub- Sailer (1976) deals separately with female species broadly distributed through the and male specimens. Based on those keys, central plains (Sailer 1976). The subspe- our female specimens are T. v. californica cies T. V. californica Sailer was described but our male specimens are T. v. verticalis based on specimens from central Califor- (Fieber). The range for T. v. verticalis ex- nia (Sailer 1976) and its known distribu- tends along the coast from Maine to Mex- tion was subsequently extended north ico and includes the West Indies (Sailer through Oregon and Washington 1976). In Sailer's key, a critical character & (Stonedahl Lattin 1986). All previous for males is the ratio of the length of the BC records have been attributed to this closest separation of the eyes (10) to the subspecies (Scudder 1977). Trichocorixa length of the hind margin of the eye (Lg). verticalis californica is listed as potentially In T. V. californica the ratio is greater than rare or endangered in British Columbia or equal to one; the ratio is less than one in (Scudder 1994) and is considered a species T. V. verticalis. In our specimens, IO:Le is of special concern in the Georgia Depres- less than one. In order to check Sailer's sionRegion (Scudder 1996). key, this ratio was measured for two male The mainland Trichocorixa specimens paratypes of T. v. californica (CA, San were collected in Delta, south of Vancou- Mateo Co., Moss Beach, 4.vii.l929, R.L. ver, from a ditch on the north side ofDel- Usinger) and for two male specimens ofT. taport Way in early October 2003 and V. verticalis (Bermuda Island, Spittal Pond, again in late May 2004. The ditch runs 10.viii.l940, G. Kelly); all four specimens inland from the coast and connects at its are in the Essig Museum at the University 'Spencer Entomological Museum, Department ofZoology, University ofBritish Columbia, Vancouver, BC V6T 1Z4 148 J.Entomol. Soc.Brit.Columbia 101,December2004 of California Berkeley. These four speci- needed. In view of the uncertainty in as- mens fulfill Sailer's criteria. signing subspecies to the BC specimens, In a further effort to identify our speci- we prefer to leave the determination as mens, we examined the left and right simply T. verticalis. claspers from one of the male specimens. In addition to T. verticalis, we collected Comparison of these claspers with the four other species of corixids from the drawings for the various species ofTricho- ditch in Delta: Cenocorixa blaisdelli corixa in Sailer (1976) showed the best (Hungerford), Corisella inscripta (Uhler), agreement between our specimen and T. Hesperocorixa atopodonta (Hungerford) verticalis. However, within the subspecies and Sigara omani (Hungerford). Ceno- of T. verticalis, the claspers of our speci- corixa blaisdelli is listed as potentially rare men are in poorest agreement with those or endangered in British Columbia shown for T. v. californica; they are in (Scudder 1994) and Corisella inscripta is much better agreement with those of the listed as rare or very local in occurrence in three more easterly subspecies. Canada (Maw et al. 2000). These records We rechecked the identification of all highlight the importance of surveying of the BC Trichocorixa specimens in the these often overlooked habitats. Voucher Spencer Entomological Museum (three specimens forall ofthese records are in the localities with a total of two males, five SpencerEntomological Museum. females and one immature). The five fe- Examination ofthe corixids in the col- male specimens key out to T. v. califor- lection at UBC showed that two entries nica. One of the males is teneral and is were omitted from the recent Checklist of partially collapsed; it cannot be run Hemiptera ofCanada and Alaska (Maw et through the key. The second male is dam- al. 2000), one each for BC and NT, based aged but the ratio of 10: Lg can be meas- on the following records: ured and is less than one, in agreement Hesperocorixa minorella (Hungerford): with the Delta specimens. Thus at least one BC, Banks Is., Kooryet Bay, sphagnum ofthe male Trichocorixa specimens previ- bog, ll.viii.l986, G.G.E. Scudder, 1 male, ously collected in BC also does not fit 4 females; BC, Diana L., sphagnum bog, Sailer's description of T. v. californica. It 14.viii.l986, G.G.E. Scudder, 2 males. is unclear whether the definition of T. v. Sigara lineata (Forster): NT, Hay R., californica needs to be broadened to ac- Mackenzie Hwy., 20.vii.l961, T.G. North- count for the geographical variation repre- cote, 1 male, 2 females. sented by the BC specimens or if the BC We thank G.G.E. Scudder for useful RDK specimens belong to a different subspecies. discussions. thanks Cheryl Barr for A re-examination ofthe whole question of her hospitality and access to the specimens subspecific designations for T. verticalis is inthe Essig Museum. REFERENCES Maw, H.E.L., R.G. Foottit, K.G.A. Hamilton and G.G.E. Scudder. 2000. Checklist ofthe Hemiptera of CanadaandAlaska.NRGResearchPress,Ottawa,Ontario,Canada. Sailer, R.I. 1976. The Genus Trichocorixa (Corixidae, Hemiptera). pp. 289-407 in: H.B. Hungerford. The CorixidaeoftheWesternHemisphere.TheUniversityofKansasScienceBulletin32. Scudder, G.G.E. 1977. Anannotatedchecklistofthe aquatic andsemiaquatic Hemiptera(Insecta)ofBrit- ishColumbia. Syesis 10: 31-38. Scudder, G.G.E. 1994. An annotated systematic listofthe potentiallyrare andendangered freshwaterand terrestrial invertebrates in British Columbia. Entomological Society ofBritish Columbia, Occasional Paper2,April 1994. Scudder, G.G.E. 1996. Terrestrial and freshwater invertebrates ofBritish Columbia: priorities for inven- tory and descriptive research. Research Branch, BC Ministry of Forests, and Wildlife Branch, BC MinistryofEnvironment,LandsandParks, Victoria,BC, WorkingPaper09/1996. Stonedahl, G.M. and J.D. Lattin. 1986. The Corixidae ofOregon and Washington (Hemiptera: Heterop- tera). Agricultural Experimental Station, Technical Bulletin 150, Oregon State University Press, Cor- vallis,Oregon.