Pseudoholostrophus (Holostrophinus) discolor ( Horn, 1888 )

Pollock, Darren, 2008, Review of the Canadian Eustrophinae (Coleoptera, Tetratomidae), ZooKeys 2 (2), pp. 261-290 : 269-270

Pseudoholostrophus (Holostrophinus) discolor ( Horn, 1888)

( Figs 2 , 9 , 18 , 26 )

Holostrophus discolor Horn, 1888: 36 .— Leng, 1920: 238; Csiki, 1924: 10; Poole and Gentili, 1996: 299; LeSage, 1991: 246; Nikitsky, 1998: 43, Plate 7 figs 12-15; Young and Pollock, 2002: 416. Lectotype (here designated), sex unknown, labelled “Va. / Henry Ulke Beetle Coll. CMNH Acc. No. 1645 / Holostrophus discolor Horn / LECTOTYPE Eustrophus discolor Horn design. DA Pollock 2008”, in CMNH. Paralectotype in MCZ.

Diagnosis The smooth meso- and metatibiae, widely separated eyes, conspicuous dorsal pubescence, shelf-like anterior pronotal margin, and eastern distribution serve to separate this species from all other Nearctic eustrophines.

Description TL 3.6-5.7 mm; GEW 1.6-2.4 mm; body ( Fig. 1 ) elongate oval, rather parallel-sided; dorsal color rufous, pronotum in most specimens slightly darker than elytra; some specimens with lighter humeral area on elytra; antennomeres 1-5 rufous, 6-10 rufopiceous, 11 light rufous; venter uniformly red-brown; dorsal pubescence relatively long, conspicuous, with some erect hairs; eyes ( Fig. 9 ) widely separated (space> 3x length of antennomere 1), inner eye margin slightly emarginate; antennae ( Fig. 18 ) relatively short, antennomere 7-11 distinctly widened; antennomere 7 triangular, 8-10 distinctly wider than long; antennal sensilla completely annular (as in Fig. 25 ); last maxillary palpomere slightly widened, subsecuriform; prosternal process elongate, spatulate distally, extended to past posterior margin of procoxae, bent dorsally at distal end; prothoracic episternal suture absent; elytral punctation relatively coarse, punctures not arranged in longitudinal striae; meso- and metatibiae with scattered short spines, oblique ridges absent (as in Fig. 15 ).

Distribution ( Fig. 26 ) Th is species is known from the fewest Canadian localities of any Nearctic eustrophine, i.e. only one locality in southern Quebec and one in New Brunswick. Th e species has a broader eastern distribution in the United States. US distribution: IN, MA, MD, NH, PA, RI, TN, VA.

Natural history Given that specimens of P. discolor are rarely collected, there are very few data available on its habits or biology. Label data include the following: in polypore fungus; malaise trap (NH); intercept trap (PA). According to Chantal (1985) specimens are known from small polypores on trees, notably cherry ( Prunus ) and maple ( Acer ). A single specimen from New Brunswick (CNC) bears a label stating “on or near fleshy polypore fungi on beech log”.

Material examined Specimens were examined from the following Canadian localities: QUEBEC: [or Quebec City], 7.VIII.1962, J.-C. Aubé, ( DAPC, 1) ; same locality, 7.VIII.1962, ( FMNH, 2) ; Ste-Foy Quebec, Co., 31.VII.1962, J.-C. Aube, ( AMNH, 2). NEW BRUNSWICK: Carelton Co., Wakefield, “Bell Forest Preserve”, 46.2200°N 67.7231° W, 16.IX.2006, R.P. Webster, hardwood forest, on or near fleshy polypore fungi on beech log, ( CNC, 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)