Pseudoholostrophus (Pseudoholostrophus) impressicollis ( LeConte, 1874 )

Pollock, Darren, 2008, Review of the Canadian Eustrophinae (Coleoptera, Tetratomidae), ZooKeys 2 (2), pp. 261-290 : 268-269

Pseudoholostrophus (Pseudoholostrophus) impressicollis ( LeConte, 1874)

( Figs 1 , 8 , 17 , 26 )

Eustrophus impressicollis LeConte, 1874: 69 ; Horn, 1888: 36; Leng, 1920: 238; Csiki, 1924: 10; Poole and Gentili, 1996: 299; LeSage, 1991: 246; Hatch, 1965: 67, Plate IX, fig. 1; Nikitsky, 1998: 47, Plate 7 figs 9-11; Young and Pollock, 2002: 416. Lectotype, sex unknown, labelled “Vanc. / Type 4781 / Eu. impressicollis Lec. ”, in MCZ.

Diagnosis This distinctive species can be separated from all Nearctic species of Eustrophinae by the combination of the following characteristics: uniform red-brown color, short, inconspicuous dorsal pubescence, widely separated eyes, and smooth meso- and metatibiae.

Description TL 6.0- 6.2 mm; GEW 2.1-2.7 mm. Body ( Fig. 1 ) elongate oval, moderately parallel sided. Dorsal and ventral color uniformly dark rufous, including antennae and legs; dorsal pubescence very short, inconspicuous ( Fig. 1 ); eyes ( Fig. 8 ) widely separated (> 3 x length of first antennomere), inner margin of eye slightly emarginate; antennae ( Fig. 17 ) relatively short, antennomeres 7-10 distinctly widened; antennomere 7 triangular, 8-10 wider than long; antennal sensilla completely annular (as in Fig. 25 ); last maxillary palpomere distinctly widened, securiform; prosternal process elongate, spatulate distally extended past posterior margin of procoxae, bent dorsally at distal end; prothoracic episternal suture absent; elytral punctation fine, punctures not arranged in longitudinal striae; meso- and metatibiae with scattered short spines, without oblique ridges (as in Fig. 15 ).

Distribution ( Fig. 26 ) Th is species is restricted to extreme western North America. In Canada, all known records are from Vancouver Island and the adjacent mainland of British Columbia, north to the Queen Charlotte Islands. Th is is seemingly one of the rarest, or most infrequently collected, species of Nearctic Eustrophinae ; most localities are represented by a single specimen. US distribution: WA ( Hatch 1965), OR, CA.

Natural history Little is known regarding the habits of P. impressicollis . Label data indicate the following: under bark of pine; in rotten log; fungus.

Material examined Specimens were examined from the following Canadian localities: BRITISH COLUMBIA: Gabriola , 2.VI.1994, BF & JL Carr, lot 7, ( CARR, 1) ; Qualicum , 16.IX.1962, BF & JL Carr, lot 1, ( CARR, 1) ; Vancouver Island, Kye Bay, nr. Comox , 5 m, 2.VII.1980, H. & A. Howden, ( CMNC, 1) ; Queen Charlotte Islands, Laskeek Bay, Haswell Island , 2-22.VI.2000, 52°51’42”N, 131°41’06”W, Allombert, Sylvain, ( RBCM, 1) .

Figures

Figs 1-7. Dorsal habitus of Canadian eustrophines. Fig. 1. Pseudoholostrophus impressicollis, TL = 4.3 mm; Fig. 2. Pseudoholostrophus discolor, TL = 4.8 mm; Fig. 3. Holostrophus bifasciatus, TL = 5.8 mm; Fig. 4. Eustrophus tomentosus, TL = 4.8 mm; Fig. 5. Eustrophopsis bicolor, TL = 5.6 mm; Fig. 6. Eustrophopsis confinis, TL = 5.4 mm; Fig. 7. Synstrophus repandus, TL = 6.8 mm.

Figs 8-16. Features of Canadian eustrophines. Figs. 8-14. Frontal view of head (same specimens as in Figs. 1-7). Fig. 8. Pseudoholostrophus impressicollis; Fig. 9. Pseudoholostrophus discolor; Fig. 10. Holostrophus bifasciatus; Fig. 11. Eustrophus tomentosus; Fig. 12. Eustrophopsis bicolor; Fig. 13. Eustrophopsis confinis; Fig. 14. Synstrophus repandus. Figs. 15-16. Hind tibia. Fig. 15. H. bifasciatus; Fig. 16. E. tomentosus.

Figs 17-25. Antennae of Canadian eustrophines. Fig. 17. Pseudoholostrophus impressicollis; Fig. 18. Pseudoholostrophus discolor; Fig. 19. Holostrophus bifasciatus; Fig. 20. Eustrophus tomentosus; Fig. 21. Eustrophopsis bicolor; Fig. 22. Eustrophopsis confinis; Fig. 23. Synstrophus repandus; Fig. 24. E. tomentosus, antennomeres 9-11 (sensillar field indicated by stippling); Fig. 25. S. repandus, antennomeres 9-11 (sensillar field indicated by stippling). Scale bar = 0.25 mm (Figs. 17-23); 0.1 mm (Figs. 24-25).

Fig. 26. Canadian distribution of Pseudoholostrophus impressicollis (squares) and P. discolor (circles). Inset shows US distribution, by state. Open square indicates state record from Hatch (1965)