Stygoporus oregonensis Larson and Labonte, 1994

Miller, Kelly B., Gibson, James R. & Alarie, Yves, 2009, North American Stygobiontic Diving Beetles (Coleoptera: Dytiscidae: Hydroporinae) with Description of Ereboporus naturaconservatus Miller, Gibson and Alarie, New Genus and Species, from Texas, U. S. A, The Coleopterists Bulletin 63 (2), pp. 191-202 : 198-199

Stygoporus oregonensis Larson and Labonte, 1994

( Figs. 9–12 )

Stygoporus oregonensis Larson and Labonte 1994: 371 ; Nilsson 2001: 189; Larson et al. 2000: 138.

Type Species. Stygoporus oregonenesis Larson and Labonte, 1994 by original designation.

Type Locality. U.S.A., Oregon, Polk County, 7 km NNE Dallas, Smithfield Road , 44.973 ° N, 123.275 ° W, 90 m, well .

Diagnosis. This species is unique within Hydroporini in having the following combination of characters: 1) compound eyes absent; 2) prosternal process inserted dorsad of the anterior margin of the metasternum; 3) with longitudinal impressions laterally on the pronotum ( Fig. 9 ); 4) metacoxal processes together truncate posteriorly; 5) with natatory setae on the metatarsus and metatibia.

Discussion. This species was described from nine specimens collected from a shallow well. The owners of the well, thinking the beetle may be a pest, chlorinated the well and the species has not been seen since (Larson and Labonte 1994). Larson and Labonte (1994) suggested that the presence of specimens in this particular well (an old well with no previous indication of a diving beetle fauna) may have been the result of an unusually large amount of precipitation that year in the region, possibly resulting in a change in the nature of the aquifer and temporarily allowing beetles into the well.

Relationships. Larson and Labonte (1994) speculated that Stygoporus is the sister group to Sanfilippodytes Franciscolo based on the enlarged metatrochanters and produced posterior margin of the medial portions of the metacoxa. Sanfilippodytes occur in seeps and springs, and seem to be a likely candidate for occurrence in underground waters. One species, S. sbordonii Franciscolo , was described from a cave in Mexico ( Franciscolo 1979). Although not anophthalmic like Stygoporus , S. sbordonii does have smaller eyes than typical Sanfilippodytes (Larson and Labonte 1994) .

Figures

Figs. 6–16. Subterranean Dytiscidae. 6–8) Comaldessus stygius, 6) dorsal habitus, 7) male genitalia, ventral aspect, 8) male genitalia, right lateral aspect. 9–12) Stygoporus oregonensis, 9) dorsal habitus, 10) male median lobe, right lateral aspect, 11) male median lobe, ventral aspect, 12) male right lateral lobe, right lateral aspect. 13–16) Haideoporus texanus, 13) dorsal habitus, 14) male median lobe, right lateral aspect, 15) male median lobe, ventral aspect, 16) male right lateral lobe, right lateral aspect. Scale bar 5 0.5 mm.