Hylastes undetermined

Mandelshtam, M. Yu. & Petrov, A. V., 2019, A key to species of the tribe Hylastini LeConte, 1876 (Coleoptera: Curculionidae: Scolytinae) from Russia and adjacent countries, Russian Entomological Journal 28 (4), pp. 389-399 : 390-391

KEY TO THE HYLASTES SPECIES OF RUSSIA AND NEIGHBORING COUNTRIES.

1. Pronotum subrectangular, anterior half wider or of equal width to the posterior half, 1.2–1.35 x as long as wide, pronotal disc with strong elongated punctures, longitudinal median area impunctate, slightly elevated, elytra 1.85– 2.00 x as long as wide, with strongly developed striae, interstriae with fine recumbent setae, replaced on declivity by minute scales and single rows of semi-erect bristles. Rostrum with a very fine, sometimes inconspicuous longitudinal keel. Apex of male ventrite 5 with faint median impression, covered by minute erect setae, pubescent area forms small triangle; male genitalia as in Fig. 23 ; 3.0– 4.5 mm ................................................................ H. linearis

— Pronotum widest on posterior half, 0.9–1.2 x as long as wide, pronotal disc with more or less round punctures, median impunctate area variable, short or long .......... 2

2. Rostrum without extensive transverse impression, either with weak impression just above mandibles or without impression and without an elevated longitudinal median keel ( Fig. 16 ) ................................................................ 6

— Rostrum with transverse impression occupying at least 1/3 of rostrum length, with longitudinal median keel, sometimes feebly developed or interrupted above upper border of transverse impression ( Fig. 15 )............................... 3

3. Elytral interstriae both on disk and on declivity covered by recumbent golden hair-like setae arranged in 3 unregular rows ( Figs 2, 5 ), these rows continue on declivity; declivital scales are microscopic and barely noticeable only on elytral declivity apex; male ventrite 5 with weakly developed median impression visible only at apex of ventrite, central part covered with pale setae forming a triangular brush ( Fig. 28 ); male genitalia with apophyses separated at base, without apical plates at penis apex ( Figs 21–22 ); 3.6–4.1 mm ............................................. H. substriatus

— Elytral interstriae on disk with recumbent pale hair-like setae, in some species setae very small, barely noticeable ( Figs 1, 3–4 ); on apical declivity clearly visible minute recumbent scales substitute for these setae and, besides, declivital interstriae with single rows of erect pale bristles ( Fig. 6 ); in males median impression of ventrite 5 conspicuous and clearly visible from apex of ventrite up to its center, lateral portions of ventrite 5 weakly elevated ( Figs 27, 29–30 ); male genitalia with apophyses fused at base, penis apex with large apical plates ( Figs 24–25 ) ........ 4

4. Pronotum wide, 0.94–1.15 x as long as wide, slightly constricted on anterior third or sides in anterior third rectilinearly narrowing towards the rounded apex ( Figs 1 , 18 ). Elytra short and broad, 1.46–1.76 x as long as wide, equal in width or wider than pronotum, elytral interstriae on disc with short recumbent pale hair-like setae arranged in two or three rows ( Fig. 1 ). Pronotal punctures large, deep, densely located, space between punctures with fine reticulation ( Fig. 11 ). In males ventrite 5 with subapical median impression and broad trapezoid tuft of light yellow setae ( Fig. 30 ); often longitudinal carina in frons short, developed usually in epistomal area only and is interrupted when continues to front; 3.5–4.6 mm ......... .............................................................. H. cunicularius

— Pronotum distinctly longer than wide, oval, without constriction in the anterior third, sides of pronotum in basal half almost parallel, straight; body more slender, elytra 1.6–2.0 x as long as wide, distinctly wider than pronotum; space between punctures on pronotal disc without reticulation ( Figs 9–10 ); in males ventrite 5 with triangular tuft of setae ......................................................................... 5

5. Surface of pronotum and elytra shining ( Fig. 10 ); lateral sides of pronotum rounded on apical third; in males triangular hair tuft on ventrite 5 with glabrous longitudinal median area dividing tuft into two parts ( Fig. 29 ); 3.4– 4.8 mm ...................................................... H. brunneus

— Surface of pronotum and elytra dull ( Fig. 9 ); lateral sides of pronotum subparallel; in males triangular tuft of setae on ventrite 5 entire without glabrous median area ( Fig. 27 ); 3.4–4.8 mm ........................................................ H. ater

6. Pronotum short, only slightly elongated, 1.05–1.09 x as long as wide. Rostrum flat, with short longitudinal median pit above transverse depression on epistoma. Elytra either black or brown. Body length not exceeding 3.0 mm .... 8

— Pronotum very short and oval, 1.01–1.04 x as long as wide, with weak constriction in anterior third. Rostrum weakly convex with only weakly marked transverse impression above epistoma, without pit. Elytral interstriae with two rows of hair-like setae on disk and one row of setae on declivity. Body color black. 2.5–3.5 mm ..... 7

7. Elytral striae strongly punctured; interstriae slightly wid- er than striae. Pronotum 1.01–1.03 x as long as wide, densely punctured and with median keel-like longitudinal impunctate area. 2.9–3.5 mm ....................... H. opacus

— Elytral striae more coarsely punctured; interstriae as wide as striae. Pronotum slightly longer, 1.04 x as long as wide. 2.6–3.5 mm ............................................... H. plumbeus

8. Pronotum with weak constriction in anterior third. Elytral striae deeply and coarsely punctured; interstriae narrower than striae, each with a single row of hair-like setae from base to declivital apex; these setae are recumbent on disc and semi-erect and bristle-like on declivity. Body blackish-brown or elytra may be reddish-brown. 2.0– 2.6 mm. .................................................................. H.attenuatus

— Pronotum oval, without signs of constriction in anterior third. Elytral interstriae as wide as striae, with two rows of recumbent hair-like setae in the basal half and one row of semi-recumbent hair-like setae on declivity. Body black. 2.5–3.0 mm ............................................. H. angustatus

Figures

Figs 21–26. Male genitalia of bark beetles from genera Hylastes and Hylurgops: 21–22 — Hylastes substriatus; 23 — Hylastes linearis; 24 — Hylastes ater; 25 — Hylastes brunneus; 26 — Hylurgops palliatus; 21, 23–26 — dorsal view; 22 — lateral view. Рис. 21–26. Гениталии самцов короедов родов Hylastes и Hylurgops: 21–22 — Hylastes substriatus; 23 — Hylastes linearis; 24 — Hylastes ater; 25 — Hylastes brunneus; 26 — Hylurgops palliatus; 21, 23–26 — сверху; 22 — сбоку.

Figs 12–20. Habitus and details of bark beetles of the genus Hylastes and Hylurgops:12, 15, 17 — Hylastes substriatus; 13 — Hylastes ater; 14 — Hylurgops palliatus; 16 — Hylastes attenuatus; 18 — Hylastes cunucularius;19–20 — Hylurgops glabratus; 12 — protibia and tarsus; 13–14 — tarsi; 15–16 — head; 17–19 — pronotum; 20 — habitus, dorsal view. Рис. 12–20. Габитус и детали строениЯ короедов родов Hylastes и Hylurgops: 12, 15, 17 — Hylastes substriatus; 13 — Hylastes ater; 14 — Hylurgops palliatus; 16 — Hylastes attenuatus; 18 — Hylastes cunucularius; 19–20 — Hylurgops glabratus; 12 — переднЯЯ голень и лапка; 13–14 — лапки; 15–16 — голова; 17–19 — переднеспинка; 20 — габитус, сверху.

Figs 1–6. Bark beetles of the genus Hylastes: 1 — Hylastes cunicularius; 2, 5 — H. substriatus; 3 — H. brunneus; 4, 6 — H. ater; 1–4 — habitus, dorsal view; 5–6 — elytral declivity; 1–4 — males; 1, 3 — Photographs from www.zin.ru\Animalia\Coleoptera. Author Kirill V. Makarov. Used with permission as indicated on website. Рис. 1–6. Короеды рода Hylastes: 1 — Hylastes cunicularius; 2, 5 — H. substriatus; 3 — H. brunneus; 4, 6 — H. ater; 1–4 — габитус, вид сверху; 5–6 — скат надкрылий; 1–4 — самцы; 1, 3 — фотографии с www.zin.ru\Animalia\Coleoptera. Автор К.В. Макаров. ИспольЗуютсЯ с раЗрешениЯ автора.

Figs 27–30. Male ventrites 5 of bark beetles of the genus Hylastes: 27 — H. ater; 28 — H. substriatus; 29 — H. brunneus; 30 — H. cunicularius. Рис. 27–30. ПЯтые членики брюшка самцов короедов рода Hylastes: 27 — H. ater; 28 — H. substriatus; 29 — H. brunneus; 30 — H. cunicularius.

Figs 7–11. Details of bark beetles from genera Hylastes and Hylurgops: 7, 9 — Hylastes ater; 8 — Hylurgops palliatus;10 — Hylastes brunneus; 11 — Hylastes cunicularius; 7–8 — proventriculus; 9–11 — punctures of pronotal disc; 7–8 — photographs by Kirill V. Makarov. Рис. 7–11. Детали строениЯ короедов родов Hylastes и Hylurgops: 7, 9 — Hylastes ater; 8 — Hylurgops palliatus; 10 — Hylastes brunneus; 11 — Hylastes cunicularius; 7–8 — провентрикулюс; 9–11 — пунктировка переднеспинки; 7–8 — фотографии К.В. Макарова.