Hylurgops planirostris ( Chapuis, 1869 )

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 : 319-321

Hylurgops planirostris ( Chapuis, 1869)

( Figures 2 b, 7b, 12c, 14a, 15b, 17b, 18)

Hylastes planirostris Chapuis, 1869:21 (Rachos de Suapam, near Cordoba, Veracruz, Mexico) Hylurgops planirostris, Hopkins, 1905:81

Diagnosis. Hylurgops planirostris is distinguished from the sympatric H. incomptus by the wider than long pronotum which is distinctly constricted anteriorly ( Fig. 14 a), by the larger and coarser pronotal punctures, and by the procurved anterior margin of each elytron. It can be distinguished from H. knausi occurring north of the Trans- Mexican Volcanic Belt, by the distinct constriction of the anterior margin of the pronotum and. It differs from the Nearctic H. rugipennis and H. pinifex by the brown coloration and by the coarse and dull interpuncture surface of the pronotum.

Description. Size Length 3.8–5.2 (avg. 4.6 ± 0.4) mm long, 2.6× longer than wide. Color. Mature adult black to brown, dark reddish-brown to black. Frons. Vertex convex or with shallow, short, vertical impression, if present with raised central rounded area below; shallow to moderately deep and slight procurved transverse mid-frontal impression, vestiture hair-like setae, longer below mid-impression 2–7× length diameter of average frontal puncture; epistomal brush with reddish-brown setae. Pronotum. Broad 0.9–1.0 (0.93 ± 0.03), distinctly constricted anteriorly, widest anterior to middle; lateral margin rounded especially anterior to middle, constricting near apical edge; dorsal middle line distinctly elevated, extending from base up to anterior impression, surface granulate to reticulate, dull to semi glossy; small discal punctures abundant, large slightly less than twice diameter of small; inter-puncture area granulate or with minute reticulation; vestiture distinct, consisting of short, recumbent, reddishbrown hair-like setae, 2× the diameter of a large puncture. Elytra. Anterior margin procurved; striae slightly concave, punctures keyhole-shaped ( Fig. 12 c), half their diameter apart; interstriae 1.5× wider than striae, surface minutely punctured (visible at> 100×), each with a short, recumbent hair-like setae and an uniseriate row of erect bristles rising from a central puncture, separated by 1.5 the width of a strial puncture, slightly longer than a discal strial puncture. Declivity. Second interstriae slightly impressed with conical granules, 3rd interstriae widest not intersecting 4th; vestiture of dense reddish-brown scale like setae and longer that declivital puncture, thick, erect reddish-brown hair-like setae rising from each granule. Ventral sclerites. Surfaces granulate to reticulate; mesoventrite anterior margin straight; tarsi dark reddish-brown, tibiae with 3 short socketed teeth before apical angle. Aedeagus. Lacking a ventral lobe ( Fig. 7 b).

Gallery: Longitudinal, biramous with irregular branches, extending downward from the entrance hole ( Schwerdtfeger 1957).

Material examined. 124 specimens. GUATEMALA. Baja Verapaz: 39 mi. SE Coban ( DEBC). Totonicapan: 7 mi. SE Totonicapan ( DEBC), 8 mi. SE Totonicapan ( DEBC). HONDURAS: El Paraiso: Cerro Montserrat, 7 km Yuscaran ( USNM); Francisco Morazan: Cerro Uyuca Morazan 30 km E Tegucigalpa ( DEBC). MEXICO. Chiapas: 5 mi. S San Carlos ( DEBC), 5 mi. E San Cristobal ( CNCI), 5 mi. NE San Cristobal ( CNCI), 5 mi. SW San Cristobal ( CNCI), 5 mi. SW El Bosque ( CNCI), 8 mi. NE San Cristobal ( CNCI), San Cristobal ( CNCI). Hidalgo: km 181 Rd Mexico-Tuxpan ( CNCI). Mexico State: Mexico City ( CNCI), Izta-Popo ( CNCI). Michoacan: 33 mi. E Morelia ( DEBC). Oaxaca: 32 mi. S Valle Nacional ( CNCI), 37 mi. S Valle Nacional ( CNCI), 40 mi. S Valle Nacional ( CNCI), 52 mi. N Valle Nacional ( CNCI), 53 mi. S Valle Nacional ( CNCI), Hwy 175, 3 mi. N Suchixtepec ( CNCI), Juquila Mixes, Yautepec ( DEBC). Puebla: 6 mi. W Teziutlan ( CNCI), Iztaccihuatl ( CNCI). Veracruz: 7 mi. SE Las Vigas ( DEBC).

Hosts: Abies religiosa , Pinus ayacahuite , P. hartwegii , P. caribaea var. hondurensis , P. leiophylla , P. montezumae , P. tecunumanii , Pinus pseudostrobus var. apulcensis , P. chiapensis .

Distribution ( Fig. 18 ). NORTH AMERICA-CENTRAL AMERICA: From the Trans-Mexican Volcanic Belt in Mexico in the north to the Sierra Madre de Chiapas in southern Honduras.

Discussion. Chapuis (1869) described Hylastes planirostris as being from Mexico without specifying a locality. The determination of the type locality has remained unclear and has been suggested to be Choapan in Oaxaca, Mexico, by Dampf after the label “Suapam” ( Schedl 1940) and later by Wood (1971c) as “Suapan” (State undetermined) Mexico. The collector of the type specimen was Auguste Sallé, who collected in Ranchos de Suapam, near Cordoba in Veracruz, Mexico; therefore, this is the most likely type locality for this species.

Both Chapuis (1873) and Blandford (1896) placed H. planirostris under Erichson’s (1836) second division for having the third tarsal segments bilobed. Blandford (1896) examined specimens from Alta Vera Paz in Guatemala that he thought were different from H. planirostris ( knausi , present designation) specimens of Mexico. He considered the Guatemalan specimens to resemble H. rugipennis , differing from it by the closer and more rugose pronotal punctures. However, he could not define characters to separate the Guatemalan specimens from the Mexican. Hopkins (1905) agreed with Blandford’s (1896) observations and found similarities between a specimen of H. planirostris from Mexico City and H. rugipennis . Hopkins (1905) mentioned the specimen could be separated from the Nearctic H. rugipennis by the “obscure punctures” and “fine rugosities” of the pronotum, and placed H. planirostris under Hylurgops based on the characters of the bilobed third tarsal segments.

Wood (1971c) studied all Chapuis’ syntypes and his homotypes of H. knausi Swaine and considered it identical to H. planirostris , placing them in his key ( Wood 1982) under the species with longer than wide pronota and obscure anterior pronotal constrictions. The possibility that Wood did not study the forms with wider pronotum occurring from the Trans-Mexican Volcanic Belt to the south should be considered. Unlike specimens previously placed under H. knausi ( Swaine 1917) occurring north of the Trans-Mexican Volcanic Belt, specimens of H. planirostris have a wider than long pronotum that is distinctly constricted on the anterior third, with deeper and closer punctures, and dull interpuncture spaces, in addition to a reddish-yellow vestiture.

Figures

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 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 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 14. Hylurgops, prothorax proportion and shape: a) wider than long and constricted anteriorly (H. planirostris), b) longer than wide and smoothly tapering anteriorly (H. knausi).

FIGURE 18. Species distribution of Hylurgops knausi (squares), including the main hosts: Pinus ponderosae, P. arizonica, and P. durangeuensis (dark grey); and the distribution of H. planirostris (circles), with its main hosts: P. hartwegii and P. montezumae (light gray). Insert shows detail of H. planirostris ’ distribution. Host polygons adapted from Little (1991).