Hylurgops LeConte, 1876

Mercado-Vélez, Javier E. & Negrón, José F., 2014, Revision of the new world species of Hylurgops LeConte, 1876 with the description of a new genus in the Hylastini (Coleoptera: Scolytinae) and comments on some Palearctic species, Zootaxa 3785 (3), pp. 301-342 : 314

Genus Hylurgops LeConte, 1876

Type species: Hylurgops pinifex ( Fitch, 1858)

Diagnosis. It is distinguished from the similar genus Hylastes in the Hylastini by the broader third tarsal segment, by the apically broadening fifth tarsal segment, by the pronotal interspaces with abundant punctures half the size as the larger punctures, by the pronotum being as long as its width, and by the distinct middle impression of the frons without an inflated region immediately below.

Description. By those characters of the Hylastini ( Wood 1982) and the following: Size. (N=200). Length 2.2– 5.9 (avg. 4.3 ± 0.6) mm long, 2.4–2.8× longer than wide. Color. Mature adult from dark brown to black, some bicolored with pronota darker than elytra. Frons. Middle transverse impression arching down. Eyes. Elongateoval, 2.2–2.5× longer than wide. Pronotum. Broad, length/width ratio 0.9–1.1 (avg. 1.0 ± 0.1), apically constricted or smoothly tapering; surface smooth to reticulate, spaces between large punctures with medium-sized punctures ( Fig. 3 c); interspaces narrower than diameter of larger punctures ( Fig. 3 c); impunctate midline usually present, sometimes raised from base to anterior impression, sometimes reaching apex; vestiture hair-like, whitish to reddish, indistinct to distinctly long. Elytra. Length/width ratio 1.6–2.0 (avg. 1.7 ± 0.2); bases procurved to nearly straight ( Figs. 11 a–b), margin not strongly elevated, asperities indistinct to small, rounded ( Fig. 12 a) or keyholeshaped ( Figs. 12 b–c), 9th striae indistinctly separated from 10th posterior to metacoxae; interstriae nearly as wide as striae, with three to five rows of short, recumbent, whitish to reddish-yellow, hair-like setae usually extending from middle of disc to its end, emerging from minute punctures or rugosities and a single line of long, semi-erect to erect, whitish to reddish hair-like setae, becoming longer after middle of disc, emerging behind a granule or rugosity. Declivity. Convex; striae narrower than interstriae, punctures as in elytra; 1st, 9th and 10th striae reaching apex ( Fig. 13 ), 3rd and 8th meeting above interstriae 9 and 3 junction, 6th and 7th meeting anterior and between previous, and 4th and 5th meeting or ending singly over previous, further away from apex; interstriae convex, 2nd variably impressed, 3rd widest, intersecting 4th or not, with uniseriate row of granules followed by long, hair-like setae, ground vestiture of three to five rows of short, recumbent, whitish to reddish, scale-like or hair-like setae, emerging from a minute puncture. Ventral sclerites. Procoxae subcontiguous; precoxal region acutely raised, not blunt; anterior margin of mesoventrite slightly rounded to straight ( Figs. 2 b–c); abdominal sclerites one and five longer than others, fifth more elongate in females than males; third tarsal segment distinctly (1.3–1.7×) broader than second ( Fig. 1 a), fifth near 2× broader at apex than at base. Aedeagus. Aedeagus cylindrical, proportionally shorter than in Pachysquamus . Ventrally straight with or without step-like lobe ( Fig. 6 d), dorsally arcuate. Necklike extension ( Fig. 6 c) between aedeagus and aedeagal apodemes present in some Hylastes ( Grocholski et al. 1976) is absent in New World Hylurgops ( Figs. 6 b, 7b–i). Spiculum gastrale slightly longer than aedeagus ( Figs. 7 b–i), rounded at tip, extending slightly arcuate posterior to aedeagus, and ending caudally in a fork. Tegmen with a short or completely absent manubrium ( Fig. 6 b).

Figures

FIGURE 1. Tarsal characters distinguishing Hylurgops from Hylastes: a) third tarsal segment broader than the second, the fifth tarsal segment broadening apically (Hylurgops longipennis), b) second and third tarsal segments equally broad, fifth not broadening apically (Hylastes mexicanus).

FIGURE 2. Anterior margin of mesoventrite in the Hylastini: a) distinctly pointed (Pachysquamus subcostulatus), b) slightly rounded and sub-inflated (Hylurgops planirostris), c) truncate, margin straight (Hylastes salebrosus).

FIGURE 3. Detail of Hylastini galleries: a) Pachysquamus subcostulatus, maternal (red) and larval gallery (adapted from Cibrián-Tovar et al. 1995), b) Hylurgops pinifex (eastern form), maternal (red) and larval gallery (adapted from Blackman 1919).

FIGURE 6. Aedeagus and spiculum gastrale: a) Pachysquamus subcostulatus, b) Hylurgops reticulatus, c) Hylastes ater (modified from Grocholski et al. 1976), d) Hylurgops rugipennis.

FIGURE 7. Aedeagus of the New World Hylurgops and Pachysquamus: a) Pachysquamus subcostulatus, b) Hylurgops planirostris, c) H. rugipennis, d) H. pinifex, e) H. incomptus, f) H. longipennis, g) H. knausi, h) H. reticulatus, and i) H. porosus.

FIGURE 11. The anterior margin of elytra in the Hylastini. a) anteriorly procurved as in Scierus and some Hylurgops (H. pinifex), b) nearly straight as in most Hylastes (H. mexicanus).

FIGURE 12. Shape of elytral disc strial punctures in Hylurgops: a) round (H. longipennis), b) keyhole-shaped (H. pinifex), and c) keyhole-shape variation (H. planirostris).

FIGURE 13. Declivity strial pattern of Hylurgops: a) third striae not touching the sixth (H. pinifex eastern form), b) third striae sometimes touching the sixth (H. rugipennis).