Brychius, Thomson, 1859

Barman, E. H., Michat, M. C., Alarie, Y. & Wolfe, G. W., 2007, Figs. 16 – 17. 16 in A Description of the First Instar of Hoperius planatus Fall, 1927 (Coleoptera: Dytiscidae: Colymbetinae: Colymbetini), with Phylogenetic Implications, The Coleopterists Bulletin 61 (3), pp. 351-397 : 351-397

Key to the adults of Nearctic species of Brychius

1. Prosternal process constricted at the level of procoxae, gradually widening posteriorly to apex making the anterior lobe distinctly wedge-shaped ( Fig. 6c ); last abdominal segment with blunt point; hood lobe of aedeagus truncated, a deep distinct channel separating it from the median lobe ( Fig. 11c )................................................ Brychius pacificus Carr

– Prosternal process constricted at the level of procoxae, nearly parallel to apex ( Figs. 6a, b ); last abdominal segment with long sharp point; hood lobe of aedeagus rounded, not distinctly separated from the median lobe.......... 2

2. Humeral margin of elytron with serrations; large specimens, total length 3.7– 4.4 mm; aedeagus with apex of median lobe long and slender, narrowing at the tip; hood lobe pointed ( Fig. 11b ).......... Brychius hungerfordi Spangler

– Humeral margin of elytron without serrations; total length 3.0– 3.8 mm; aedeagus with curvature of the median lobe not pronounced, apex rounded and the hood lobe small, laying almost against the median lobe ( Fig. 11a )................................................. Brychius hornii Crotch

Figures

Fig. 6. Prosternal and metasternal processes of adult Nearctic Brychius spp. (Coleoptera: Haliplidae): a) B. hornii Crotch; b) B. hungerfordi Spangler; c) B. pacificus Carr.

Fig. 11. Aedeagus of Nearctic Brychius spp. (Coleoptera: Haliplidae): a) B. hornii Crotch; b) B. hungerfordi Spangler; c) B. pacificus Carr.