Hylurgops incomptus ( Blandford, 1897 )

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 : 326-328

Hylurgops incomptus ( Blandford, 1897)

( Figures 7 e, 15e, 17e, 20, 21)

Hylastes incomptus Blandford, 1897:145 (Syntypes: Andres Chalchicomula, now Ciudad Serdan in Puebla, Mexico (1), Salazar (1), Chilpancingo in Guerrero (1))

H. (Hylurgops) incomptus, Hagedorn, 1910:45

Hylurgops incomptus, Kleine, 1912:166

H. grandicollis Swaine, 1917:17 (Cloudcroft and Santa Fe, New Mexico, USA)

Synonymy: Wood, 1957:397

Diagnosis. Hylurgops incomptus is distinguished from all other Hylurgops by the nearly complete acute margin of the sides of its pronotum ( Fig. 20 a). Is distinguished from the sympatric H. longipennis by its larger size, by having a pronotal base almost as broad as the elytral base, by the smaller and more abundant pronotal punctures, and by the long and yellowish hair-like vestiture.

Description. Size. Length 4.3–5.5 (avg. 4.9 ± 0.4) mm long, 2.7× longer than wide. Color. Mature adult black. Frons. Transverse impression moderately strong; lower carina distinct, elevated from epistomal margin to convexity below frontal impression, where it bifurcates until reaching it; vestiture hair-like, longer below middle impression, 4–7× the length of a puncture’s width. Pronotum. Slightly longer than wide 1.0–1.1 (1.0 ± 0), widest at base smoothly tapering to basal ⅔ ( Fig. 20 b), anterior ⅓ strongly, roundly narrowing anteriorly; basal ¾ of lateral margin sharply elevated, anterior ¼ less sharply elevated, broadly rounded; middle line indistinct, not raised, indicated by lack of punctures from base to anterior edge, interpuncture surfaces smooth; discal punctures small, deeply impressed, abundant, of two different sizes, large 2–2.5× size of small; vestiture distinct, length of erect discal setae 3–6× the width of a large discal puncture, 5–9× around margins. Elytra. Anterior margin almost straight, with scattered medium-sized crenulations; strial punctures, small, round; interstriae 2–3× wider than striae, surface usually glossy but reticulate in some specimens; interstriae with two rows of punctate granules, each with a long, semi erect, hair-like setae from elytral disc to declivity, flanking an erect, thicker and longer (4–6× length discal puncture diameter) hair-like setae arising from uniseriate granules. Declivital vestiture more abundant than on disc, scale-like setae usually absent, in their place hair-like setae present. Declivity. 2nd interstriae impressed, 3rd not distinctly wider than 2nd and not widened apically, all with pointed granules medially, height up to ½ width of declivital puncture, separated by 1.5× size of discal puncture; surface with four to five rows of minute oval punctures with acuminate serrations on their blunt apices; vestiture consisting of uniseriate row of long, erect, hair-like setae intercalated in two lateral rows of slightly shorter hair-like setae. Ventral sclerites. Finely reticulate. Legs. Protibiae with 1–2 large socketed teeth before the angle, meso- and metatibiae with two large socketed teeth each, before the angle; third tarsal segments slightly broader than others. Variation. Specimens from southern Arizona and New Mexico. Pronotum smoothly broadening on basal ⅔ ( Fig. 20 c), interpuncture surfaces reticulate. Elytral disc always reticulate, the long hair-like setae bearing granulate lateral rows on interstriae and declivity absent, bearing scale-like setae on declivity. Specimens from Durango, Mexico are intermediate (see discussion). Aedeagus. Lacking a ventral lobe ( Fig. 7 e).

Gallery: The maternal gallery is constructed near or below the root collar, upward from the entrance hole, longitudinal and slightly sinuate from 60–120 mm long ( Schwerdtfeger 1957). The larval tunnels extend from both sides of the maternal gallery ( Wood 1982).

Material examined. 108 specimens. MEXICO. Chiapas: 5 mi. E San Cristobal ( CNCI), 6 mi. NE San Cristobal ( CNCI), 7 mi. E San Cristobal ( CNCI), 8 mi. E San Cristobal ( CNCI), 8 mi. SE San Cristobal ( CNCI), 25 mi. SE Teopisca ( CNCI), San Cristobal ( CNCI). Chihuahua: Mesa del Huracan ( CNCI). Durango: 9 mi. E El Palmito ( CNCI), 10 mi. SW El Salto ( CNCI), 10 mi. SW El Salto ( CNCI). Mexico DF: 15 mi. S El Guarda ( CNCI). Mexico State: 40 mi. W ( DEBC); Vivero San Cayetano ( DEBC). Nuevo Leon: Cerro Potosi ( CNCI). Oaxaca: 17.9 km E Teotitlan ( DEBC), Hwy. 175, 3.5 mi. S Suchixtepec ( CNCI). Puebla: 6 mi. W Teziutlan ( CNCI). Vera c ruz: 3.6 mi. W Las Vigas ( CNCI). USA. Arizona: Cochise Co.: Rustler Pk., Chiricagua Mountains ( CNCI); Pima Co.: Sta. Catalina Mountains ( CNCI); Sedona Co.: Oak Creek Canyon ( CNCI). New Mexico: Otero Co.: Cloudcroft ( RMRS), Cloudcroft Paratype 9241 ( CNCI); Santa Fe Co.: Santa Fe Canyon Paratype 9241 ( CNCI).

Hosts: Pinus arizonica , P. duranguensis , P. engelmannii , P. hartwegii , P. leiophylla , P. montezumae , P. tecunumanii , P. patula , P. ponderosae (included without revised information due to beetle records north of Mogollon Rim (the northern limit of P. arizonica ), P. pseudostrobus .

Distribution ( Fig. 21 ). CENTRAL AMERICA: Honduras, Guatemala and El Salvador; NORTH AMERICA: Arizona and New Mexico to southern Mexico.

Discussion. Blandford (1897) described this species as Hylastes incomptus under Erichson’s second division, and Hagedorn (1910) included H. incomptus under the subgenus Hylurgops . Kleine (1912) considered Hagedorn’s species concept of Hylastes to be too broad and did not follow his subgeneric concept, placing H. incomptus as a member of Hylurgops .

When Swaine (1917) described H. grandicollis from three specimens collected in New Mexico, he did not make any reference to Blandford’s (1897) species. Swaine (1917) mentioned having examined specimens from California but gave no specific locality. No specimens from California were examined during this study, and Bright & Stark (1973) did not include H. grandicollis from that state. In 1955, Schedl reported H. incomptus from Guatemala, its southernmost distribution. Wood (1957) synonymized H. grandicollis Swaine with H. incomptus Blandford after comparing Swaine’s grandicollis type with several of his and Eggers’ specimens from unspecified locations. Wood (1982) based his description on a homotype from Cerro Calel, Guatemala and examined the types of H. incomptus and H. grandicollis among 151 others.

Specimens from Arizona and New Mexico, including the Swaine H. grandicollis types, have a pronotum that gradually broadens from the base to the middle or to slightly anterior of the middle ( Fig. 20 b). These specimens also have a reticulate surface of the elytra. On the declivity, the hair-like setae are shorter, reddish-yellow, and less abundant due to the presence of a single row of medially arranged granules on the interstriae and the scale-like setae are more abundant. The pronotum of Mexican specimens from Chiapas gradually narrow from the base toward the apex ( Fig. 20 c). The elytral surface varies from reticulate to smooth and glossy, and the declivital vestiture is light-yellowish with abundant, medium length, hair-like setae due to the presence of a pair of lateral granules in addition to the central interstrial row and less abundant scale-like setae.

The occurrence of the species between the populations of southern Arizona and New Mexico is fragmented possibly due to the host patchiness in the few mountains across the Sonoran and Chihuahuan deserts. The northernmost Mexican record reported by Wood (1982) is from Mesa del Huracan in Chihuahua, about 300 km southeast of the southernmost record in Arizona in the isolated Huachuca Mountains. Specimens from these two disjunct regions are indistinguishable. Specimens from the Sierra Madre del Sur in the Mexican state of Oaxaca also closely resemble the northern specimens, except that some are smaller. The greatest differences are found between specimens occurring north of Durango, Mexico and specimens from Chiapas in southern Mexico. However, individuals from extremes of the range share some characters, suggesting that the species probably exhibit clinal variation. Collecting other material for additional morphometric and molecular analysis would help determine if specimens from these populations represent different species.

Figures

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 20. Hylurgops incomptus pronotum: a) prothoracic lateral margin, b) pronotum broadening from base (typical form), c) pronotum narrowing from base (Arizona and New Mexico variant).

FIGURE 21. Hylurgops incomptus distribution (circles) with main hosts: Pinus arizonica, P. duranguensis, and P. ponderosae (central, AZ and NM). H. longipennis distribution (triangles) with main hosts: P. hartwegii and P. patula. Insert shows sympatric zone near Mexico City.