Scolytus reflexus Blackman, 1934

Smith, Sarah M. & Cognato, Anthony I., 2014, A taxonomic monograph of Nearctic Scolytus Geoffroy (Coleoptera, Curculionidae, Scolytinae), ZooKeys 450, pp. 1-182 : 45-46

Taxon classification Animalia Coleoptera Curculionidae

Scolytus reflexus Blackman, 1934 Figs 45, 49-50

Scolytus reflexus Blackman, 1934: 13.

Scolytus virgatus Bright, 1972: 1490. syn. n.

Scolytus wickhami Blackman, 1934: 13. syn. n.

Diagnosis.

Males exhibiting the reflexus phenotype are readily distinguished by the presence of a strong recurved subapical carinate ridge on ventrite 5 that is medially produced to form a slightly recurved and subrostriform ridge that appears “reflexed”. Males of this species exhibiting the wickhami phenotype are easily confused with males of Scolytus monticolae . They are easily distinguished by the size of male ventrite 5. In Scolytus reflexus , ventrite 5 is equal in length to ventrite 4. In Scolytus monticolae , ventrite 5 is equal in length to ventrites 3 and 4 combined. Scolytus monticolae lacks an epistomal process while Scolytus reflexus typically has a strongly developed epistomal process. Females are distinguished from those of Scolytus monticolae by having the apical margin of ventrite 1 rounded and by the ventrite 2 surface rugose, shining, coarsely punctate and convex.

Description (male).

2.4-3.8 mm long (mean = 3.2 mm; n = 20); 1.8-2.5 times as long as wide. Color dark red-brown to black, antenna brown. Pronotum typically darker than elytra.

Head. Epistoma weakly to acutely, deeply emarginate; epistomal process weakly to strongly developed and elevated; median area above mandibles bearing dense patch of long, yellow, hair-like setae. Frons appearing flattened when viewed laterally, slightly transversely impressed just above epistoma; moderately, longitudinally aciculate, deeply, coarsely punctate; aciculations converging at epistoma; punctures small, coarse; moderately, uniformly covered by long, fine, yellow, erect, hair-like setae, these longer than width of midpoint of eye. Antennal scape short, elongate; club flattened, irregularly ovoid, setose with partial septum, three sharply arcuate sutures visible.

Pronotum wider than long; apical margin broadly rounded, median area between eyes lined with scales; sides distinctly arcuate, strongly constricted near apex, forming a weak transverse impression near apical margin; surface smooth, shining, punctures on disc fine, shallow, moderately abundant, larger and more abundant laterally and on apical constriction; apical, anterolateral and lateral margins bearing sparse, erect, yellow, hair-like setae; base weakly bisinuate.

Elytra with sides sub-parallel on apical half, narrowing to subquadrate, smooth apex; apex moderately emarginated at suture. Margin of apical edge bearing small, fine punctures. Disc smooth, shining; interstriae weakly impressed, more than twice width of striae, punctures uniseriate, smaller than those of striae, bearing minute, recumbent setae less than length of a puncture; striae weakly impressed. Declivity bearing sparse, short, erect yellow setae. Metepimeron half-length of metanepisternum.

Venter. Apical margin of ventrite 1 rounded, marked by weak carina on vertical surface of segment. Ventrite 2 nearly perpendicular to ventrite 1; surface rugose, shagreened, finely punctate; punctures small, coarse, shallow; surface convex; setae moderately abundant, long, erect and longer than length of ventrite 3; lateral margins of ventrites 2-3 and ventrite 4 unarmed. Ventrite 5 typically armed with strong, recurved, subapical, carinate ridge, occasionally modified and medially produced to form a slightly recurved and subrostriform ridge appearing “reflexed” (Chiricahua Mountains, Arizona and Chihuahua, Mexico populations). Ventrite 5 carinate ridge closer to apical margin of segment; length of ventrite 5 less than combined lengths of ventrites 3 and 4; setal patch and median depression absent.

Female.

2.5-4.0 mm long (mean = 3.2 mm; n = 20); 1.87-2.5 times as long as wide. Similar to male except epistoma entire, epistomal process absent, frons convex when viewed laterally, weakly longitudinally aciculate, setae sparser, shorter, less than width of eye; weakly transversely impressed just above epistoma and between inner apices of eyes. Second ventrite unarmed, setae sparse, erect, measuring length of three diameters of a puncture. Length of ventrite 5 greater than combined lengths of ventrites 3 and 4, armed with apical strongly recurved subapical carinate ridge.

Specimens examined.

358.

Type material.

Holotype Scolytus reflexus Blackman: male, labeled "Sta Catalina Mts, Ariz., Chrisman, M. Coll, Pseudotsuga taxifolia , Hopk. U.S. 12210, Reared June 1-14 H.B. Kirk, Type No. 43831 USNM" (USNM). Holotype Scolytus virgatus Bright: male, labeled "MEX., N.L., Cerro Potosi, V.2.71, 8500', D.E. Bright, Pseudotsuga menziesii , CNC No. 12604" (CNCI). Holotype Scolytus wickhami Blackman: male, labeled "Buena Vista, Col. H.F. Wickham July 1-6 '96, 7,900-8,000 ft, Type No. 43832 USNM" (USNM). Paratypes Scolytus reflexus UNITED STATES:ARIZONA: [Cochise Co.]: Chiricahua Mountains, 18.VI.[?], Hubbard, Schwarz (EMEC-1). Pima/ Pinal Co.: Santa Catalina Mountains, M. Chrisman, reared 25.VI.[19]14, H.B. Kirk, ex. Pseudotsuga taxifolia [= Pseudotsuga menziesii ] (EMEC-1). Paratypes Scolytus wickhami UNITED STATES:ARIZONA: [Cochise Co.]: Chiricahua Mountains, Hopk. U.S. 5558-A, 5.VIII.[19]07, J.L. Webb, ex. Pseudotsuga taxifolia [= Pseudotsuga menziesii ] (CNCI-1). NEW MEXICO: [Lincoln Co.]: Capitan Mountains, Hopk. U.S. 5674, J.L. Webb, ex. Pseudotsuga taxifolia [= Pseudotsuga menziesii ] (CNCI-1). Paratypes Scolytus virgatus MEXICO:Nuevo León: Cerro Potosi, 8500 ft, 2.V.[19]71, D.E. Bright, ex. Pseudotsuga menziesii (CNCI-4).

Non-type material.

MEXICO: CHIHUAHUA: San Juanito, 16 km N.E., 50 m, 19.VII.1960, S.L. Wood, ex. Pseudotsuga menziesii (MSUC-3, USNM-7). San Juanito, Hopk. U.S. 58592, 16.III.1974, M.M. Furniss, ex. Pinus sp. (USNM-1, WFBM-5). DURANGO: Durango, Hopk. U.S. 58685, 24.III.1974, M.M. Furniss, ex. Pseudotsuga menziesii (USNM-14). UNITED STATES:ARIZONA:Cochise Co.: Chiricahua Mountains, 21.VII.1916, C.R. Bruck, (DEBC-2), 29.IX.[19]47, D.J. & J.N. Knull (DEBC-4). Coronado National Forest, Chiricahua Mountains, N31°54.915', W109°16.040', 8196 ft, 20.V.2010, S.M. Smith, ex. Pseudotsuga menziesii (MSUC-7). Huachuca Mountains, Upper Carr Canyon, 7500 ft, 6-10.VIII.[19]52, H.B. Leech, J.W. Green (CASC-1). [Coconino Co.]: Jacob Lake, Kaibab National Forest, 19.VI.[19]66, [L. Edson], ex. Pseudotsuga menziesii (EMEC-3). Greenlee Co.: Hannagan [Meadows] campground, 12.VII.1968, D.E. Bright, ex. Pseudotsuga menziesii (CNCI-5). Pima Co.: Tucson, Mount Lemmon, 11.VI.1969, S.L. Wood, ex. Pseudotsuga menziesii (MSUC-1). Pima/Pinal Co.: Santa Catalina Mountains, 9000 ft, 6.VI.1926, R.B. Streets (CASC-1); 5.VIII.1968, D.E. Bright, ex. Pseudotsuga menziesii (CNCI-1); Bear Wallow, 7800 ft, 11.VI.1969, S.L. Wood (USNM-5). Santa Cruz Co.: Carr Canyon, 8.VIII.1962, S.L. Wood, ex. Pseudotsuga taxifolia [= Pseudotsuga menziesii ] (USNM-12). Yavapai Co.: Prescott National Forest, Mount Union, Lake. Pseudotsuga menziesii (EMEC-1). COLORADO: [Boulder Co.]: Boulder, Hopk. U.S. 17700-Y, 21.IV.[19]37, J.A. Beal, ex. Pseudotsuga taxifolia [= Pseudotsuga menziesii ] (CSUC-3, USNM-5). Chaffee Co.: N. of Poncha Pass, 25.VII.1997, D. Leatherman, ex. ponderosa pine [= Pinus ponderosa ] (CSUC-1). Clear Creek Co.: Idaho Springs, 7.5 mi S., 12.VII.2007, D. Bright, B.A. Barr, ex. bole Pseudotsuga menziesii (DEBC-3). Lawson, 26.VII.1994, D. Leatherman, ex. Douglas fir [= Pseudotsuga menziesii ] (CSUC-4). Near Lawson, 26.VII.1994, S. Kelley, ex. Pseudotsuga menziesii (CNCI-2). [Garfield Co.]: Glenwood Springs, VII.[?] (CASC-1). Jefferson Co.: 1-15.VII.2010, Colorado Dept of Agriculture, ex. Lindgren funnel UHR EtOH & Ω-pinene conifer (CSUC-3). Buffalo Creek, 6.VIII.2004, D. Leatherman, ex. Douglas fir [= Pseudotsuga menziesii ] (CSUC-1). Larimer Co.: Estes Park, 19.VI.[19]35, ex. Pseudotsuga taxifolia [= Pseudotsuga menziesii ] (USNM-3); 28-VI-13.VII.2010, Colorado Dept of Agriculture, ex. Lindgren funnel UHR EtOH & Ω-pinene conifer (CSUC-3). Fort Collins, 29.VI.[19]35 (USNM-2). Mount Margaret trailhead, 4.VIII.1994, D. Leatherman, ex. Douglas fir [= Pseudotsuga menziesii ] (CSUC-1). Pingree Park, 30.VIII.1995, D. Leatherman (CSUC-1). Poudre Canyon, 27.V.1975, D. Leatherman, ex. Douglas fir [= Pseudotsuga menziesii ] (CSUC-1). Rist Canyon, 28.X.[19]56, D.E. Bright, ex. Pseudotsuga taxifolia [= Pseudotsuga menziesii ] (DEBC-1); S28 T8 NR70W, 3.III.1957, T.O. Thatcher, ex. Pseudotsuga taxifolia [= Pseudotsuga menziesii ] (DEBC-7). Rist Canyon Picnic Area, 26.VI.2008, D. Leatherman, ex. fallen Douglas fir [= Pseudotsuga menziesii ] (CSUC-3). Roosevelt National Forest, Big Thompson Canyon, N40°24.456', W105°24.565', 7080 ft, 5.V.2010, S.M. Smith, D.E. Bright, B.A Barr, ex. Pseudotsuga menziesii (MSUC-2). Red Feather Lakes, 12.III.2003, D. Leatherman, ex. Douglas fir [= Pseudotsuga menziesii ] (CSUC-1), VI.2000 (CSUC-5). CR 63E, 2 mi S. off Hwy 14, 4.VII.2007, D. Leatherman, ex. Douglas fir [= Pseudotsuga menziesii ] (CSUC-11). Mineral Co.: Wolf Creek Pass off US 160, Sheep Mountain, 25.VII.2005, D. Leatherman, ex. Douglas fir [= Pseudotsuga menziesii ] (CSUC-1). Pueblo Co.: SR 165, 5 mi S.E. San Isabel Millset trailhead, 23.VI.2000, D. Leatherman, ex. Douglas fir [= Pseudotsuga menziesii ] (CSUC-3). Teller Co.: Ridgewood Subdivision, 5.VIII.2004, D. Leatherman, ex. Douglas fir [= Pseudotsuga menziesii ] (CSUC-1). NEVADA: [Lander Co.]: Austin, 12.VIII.[19]40, D.E. Hardy (USNM-1). NEW MEXICO:Otero Co.: Cloudcroft, 4.VI.1969, tree 53, S.L. Wood, ex. Pseudotsuga menziesii (MSUC-14); 11-13.VII.[19]74, D.E. Bright, ex. Pseudotsuga menziesii (CNCI-4). Lincoln National Forest, Apache Point Observatory, N32°47.046', W105°48.841', 9116 ft, 15.V.2010, S.M. Smith, ex. Pseudotsuga menziesii (MSUC-145). [Sandoval Co.]: Jemez Springs, Hopk. U.S. 37218-F, ex. Pseudotsuga menziesii (USNM-4); Hopk. U.S. 37214-D, 1.IX.[19]57, F.M. Yasinski, ex. Pseudotsuga taxifolia [= Pseudotsuga menziesii ] (USNM-15). TEXAS:Culberson Co.: Guadalupe Mountains National Park, The Bowl, 17.VII.1974, Bright, ex. Pseudotsuga menziesii (CNCI-6). UTAH: [Utah Co.]: Wasatch National Forest, Mount Timpanogos, 13.VII.1957, D.E. Bright, ex. Abies concolor (DEBC-1). [Unspecified County]: Logan Canyon, 5000 ft, 31.XII.1945, S.L. Wood, ex. Douglas fir [= Pseudotsuga menziesii ] (USNM-3), 28.IV.1946 (USNM-2), 16.VI.1946 (USNM-4), 3.VII.1946 (USNM-4).

Distribution.

MEXICO: Chihuahua, Durango, Nuevo León. UNITED STATES: Arizona, Colorado, Nevada, New Mexico, Texas, Utah (Fig. 51).

Hosts.

Pseudotsuga menziesii (Mirb.) Franco (= Pseudotsuga taxifolia Britton) (Douglas fir).

Biology.

Scolytus reflexus is relatively common throughout its range and is found in fresh slash and branches of Douglas fir ( Edson 1967).

The adult gallery consists of two egg galleries and a central nuptial chamber. The adult gallery is parallel to the grain of the wood and bayonet shaped (Fig. 24). From the central nuptial chamber, one egg gallery extends parallel to the grain of the wood and the other egg gallery is slightly transversely extended and then extends parallel to the grain. The nuptial chamber is oblique to the egg galleries. The adult gallery equally scores the sapwood and cambium and averages 3.9-7.6 cm in length. Egg niches are closely spaced and score the sapwood. Larvae extend their mines perpendicular to the egg gallery before diverging in a fan shaped pattern. Pupation may occur under the bark or in the sapwood ( Edson 1967).

Collection notes.

The senior author has collected Scolytus reflexus in the Chiricahua Mountains, Arizona and Apache Point Observatory, New Mexico killing small (less than 10.0 cm DBH) Douglas fir trees. This species was also reported killing Douglas fir in the Sacramento Mountains and Santa Fe National Forest of New Mexico, and was tentatively and incorrectly identified as Scolytus monticolae ( USFS 2004). Scolytus monticolae strongly resembles Scolytus reflexus (see diagnosis) but does not occur in New Mexico.

Remarks.

Wood (1977: 388) placed Scolytus reflexus and Scolytus wickhami in synonymy with Scolytus tsugae . Wood (1982) removed Scolytus reflexus from synonymy with Scolytus tsugae . In this publication he also listed Scolytus wickhami as a synonym of Scolytus reflexus and cited Wood (1977) for the synonymy. Wood and Bright (1992: 364) also cite Wood (1977) for the synonymy. However, Scolytus wickhami was never removed from synonymy with Scolytus tsugae and designated as a synonym of Scolytus reflexus .

In his description of Scolytus virgatus , Bright (1972) posited that the species was closely related to Scolytus wickhami or either a subspecies or variety. Wood (1982) considered Scolytus wickhami a synonym of Scolytus reflexus , but as discussed above, never formally placed it in synonymy. All three species are here treated as one slightly morphologically variable species. We assessed intraspecific variation within these three species for four genes (Table 6). It was small for each gene with the average divergence of 1.3% for COI and less than 0.12%, 0.03% and 0.29% for 28S, CAD and ArgK respectively among sampled populations (Table 6). These ranges are consistent with variation observed within other species. There are two main characteristics found that vary among the populations: the male fifth ventrite carina and the male epistomal process. There are two main phenotypes observed in populations: reflexus and wickhami. The reflexus phenotype includes individuals that were previously considered to be Scolytus reflexus with the male ventrite 5 armed with a strong recurved subapical carinate ridge that at its crest is closer to the basal than the apical margin of the segment. The length and height of the subapical carinate ridge is also variable within populations. This character is only found in the Chiricahua Mountains, Arizona and in Mexico. The wickhami phenotype includes individuals that were formerly considered Scolytus wickhami and Scolytus virgatus . In the wickhami phenotype the process on the male fifth ventrite is reduced in the wickhami phenotype and but still forms strong recurved subapical carinate ridge. However it is important to note that both the reflexus and wickhami phenotypes are sympatric in the Chiricahua Mountains. The male epistomal process also varies from a strongly developed and elevated ridge above the epistoma to weakly developed and elevated ridge. In general, the ridge is more strongly developed in the reflexus phenotype but considerable variation is observed especially in the wickhami phenotype. Additional variation is observed in the density of punctures on the male second ventrite and the coarseness of the male frons aciculations. In addition, the gallery structure of Scolytus reflexus and Scolytus wickhami are identical; the gallery of Scolytus virgatus is has not been noted. Scolytus wickhami and Scolytus virgatus are here designated as synonyms of Scolytus reflexus .