Scolytus fiskei Blackman, 1934

Smith, Sarah M. & Cognato, Anthony I., 2014, A taxonomic monograph of Nearctic Scolytus Geoffroy (Coleoptera, Curculionidae, Scolytinae), ZooKeys 450, pp. 1-182 : 32-33

Taxon classification Animalia Coleoptera Curculionidae

Scolytus fiskei Blackman, 1934 valid sp. Figs 29, 31

Scolytus fiskei Blackman, 1934: 25.

Diagnosis.

Scolytus fiskei is very morphologically similar to Scolytus laricis and Scolytus unispinosus . Males of are distinguished from those of Scolytus laricis by the frons flattened when viewed laterally, never deeply impressed, by the moderately abundant frontal setae (compared to dense) and by the host genus, Pseudotsuga . Males are distinguished from those of Scolytus unispinosus by the following combination of characters: abdominal venter shiny in luster, the base of the ventrite 2 spine extends from the apical margin to three-quarters the length of the segment and geographical distribution east of the Rocky Mountains. The female is distinguished from that of both species by the shining luster of ventrite 2.

Description (male).

2.2-2.8 mm long (mean = 2.4 mm; n = 15); 2.1-2.8 times as long as wide. Head, antennae, pronotum, and abdominal venter dark red-brown, elytra and legs yellow-brown to light brown. Pronotum typically darker than elytra.

Head. Epistoma weakly emarginated; epistomal process present, moderately developed, low; median area above mandibles bearing dense patch of long, yellow, hair-like setae. Frons appearing flattened when viewed laterally from epistoma to vertex, slightly transversely impressed just above epistoma to inner apices of eyes; moderately, coarsely, longitudinally aciculate-punctate; aciculations converging at epistoma; punctures large, sparse and 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, two broadly 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 and anterolateral 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 not impressed, twice width of striae, punctures uniseriate, smaller than those of striae; punctures bearing short, sparse, recumbent, yellow setae slightly longer than size of a puncture (may be abraded); striae weakly impressed. Declivity bearing sparse, short, erect yellow setae. Metepimeron less than half-length of metanepisternum.

Venter. Apical margin of ventrite 1 rounded, 2 marked by weak carina. Ventrite 2 nearly perpendicular to ventrite 1; surface smooth, shining, finely punctate; punctures small, fine, shallow; covered with sparse setae less than length of segment 3; surface convex; apical margin armed with laterally compressed, median spine with base extending from apical margin to ¾ length of segment, apex rounded; lateral margins of ventrites 2-3 and ventrite 4 unarmed. Ventrite 5 carinate ridge equidistant between basal and apical margins of segment; length of ventrite 5 less than combined lengths of ventrites 3 and 4; setal patch and median depression absent.

Female.

2.2-3.5 mm long (mean = 4.65 mm; n = 15); 2.1-2.5 times as long as wide. Similar to male except epistoma feebly emarginated, epistomal process weakly developed, frons convex when viewed laterally, weakly longitudinally aciculate, setae sparser, shorter, less than width of eye; weakly transversely impressed between epistoma and inner apices of eyes. Second ventrite apical margin armed with acute median denticle, with base extending from apical margin to half-length of segment.

Specimens examined.

297.

Type specimens.

Holotype Scolytus fiskei Blackman: male, labeled "[Capitan Mountains, N. Mex. 25 April, 1907], Hopk. US 3959, W.F. Fiske Collector, Type No. 43840 USNM" (USNM).

Non-type specimens.

CANADA: BRITISH COLUMBIA: Aspen Grove, 12.VII.1931, H. Richmond (CNCI-11, FMNH-2). Clinton, 6 mi N., 7.VII.1972, D.E. Bright, ex. Pseudotsuga menziesii (CNCI-7). Creston, 8.VI.1958, H. & A. Howden (EMEC-1). Fort Steele, 14.VI.[19]26, R. Hopping (CASC-1). Indian Meadows, Midday Creek, 13.VII.1920, R. Hopping, ex. Pseudotsuga taxifolia [= Pseudotsuga menziesii ] (CASC-2, CNCI-2). Lumby, Creighton Valley, 3.VI.[19]22, R. Hopping (CASC-1). Merritt, Midday Valley, 27.VI.1926, W. Mathers (CASC-2). Trinity Valley, 24.VI.1928, J.R. Howell, ex. Pinus monticola (CASC-1), 10.VII.1928 (CASC-1). UNITED STATES:ARIZONA:Pima Co.: Tucson, Mount Lemmon, 11.VI.1969, S.L. Wood, ex. Pseudotsuga menziesii (MSUC-2). COLORADO:Boulder Co.: Nederland, 5-7 km N., 5.VIII.2009, D.E. Bright, B.A. Barr, ex. branches of Pseudotsuga menziesii (CNCI-4). [La Plata Co.]: Durango, Junction Creek Rd, 10000 ft, 12-17.VII.1968, E.C. Becker (CNCI-1). Larimer Co.: 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-36). IDAHO: [Adams Co.]: Tamarack, 10 mi S., 3.VII.1967 (WFBM-1). Boise Co.: Idaho City, 2.VI.1970 (WFBM-9), 1.I.1971 (WFBM-4). Lowman, Edna Creek, 6.VII.[19]72, A. Vaccares, G. Starr, ex. Douglas fir stump [= Pseudotsuga menziesii ] (WFBM-1). Bonner Co.: 6.VI.1986, M.M. Furniss, J.B. Johnson, ex. Pseudotsuga menziesii (WFBM-7). Priest Lake, Indian Creek, 6.VI.1986, M.M. Furniss, J.B. Johnson, ex. Pseudotsuga menziesii (WFBM-25). Priest Lake, 6.VI.1986, M.M. Furniss, J.B. Johnson, ex. Pseudotsuga menziesii (WFBM-1). Boundary Co.: Parker Creek, 8.VI.1986, M.M. Furniss, J.B. Johnson, ex. Pseudotsuga menziesii (WFBM-5). Clearwater Co.: Elk River, 12 mi S.E., Hopk. U.S. 58536, 9. VII– 16.VII.1973, R.D. Oakes (WFBM-1), 30.VII-6.VIII.1973 (WFBM-1); Hopk. U.S. 58771, 25.VI-1.VII.1974, J.M. Wells, ex. in flight (WFBM-1). Custer Co.: Herd Lake, Hopk. U.S. 60796-A, 3.IX.1978, M.M. Furniss, ex. Pseudotsuga menziesii (WFBM-9). MacKay, 9 mi N.E., 19.VII.1985, M.M. Furniss, J.B. Johnson, ex. Pseudotsuga menziesii (WFBM-3). Summit, W. of Pass Creek, 19.VII.1985, M.M. Furniss, J.B. Johnson, ex. Pseudotsuga menziesii (WFBM-12). Latah Co.: Big Sand Creek, Hopk. U.S. 53545, 11.VI.1969, M.M. Furniss (WFBM-1), 20.VI.1969 (WFBM-1). Moscow, 20.XI.1961, R.E. Stecker, ex. reared from Doug fir [= Pseudotsuga menziesii ] (WFBM-33). Moscow Mountain, Hopk. U.S. 48869, 18.VII.1967, ex. Pseudotsuga menziesii (WFBM-3). Viola, 21.VI.1985, S.J. Gast, M.M. Furniss, ex. Pseudotsuga menziesii (WFBM-2). Nez Perce Co.: Forest, III.1985, M.M. Furniss, ex. Pseudotsuga menziesii (WFBM-6). Shoshone Co.: Red Ives Ranger Station, V.1983, M.M. Furniss, ex. Pseudotsuga menziesii (WFBM-1). Valley Co.: Cascade, 7 mi E., 14.VI.1966, R.L. Furniss (WFBM-1). MONTANA:Lake Co.: Swan Lake, 28.VI.1963, M.M. Furniss, ex. Pseudotsuga menziesii (WFBM-1). Madison Co.: Alder, 18 km S.W., 8.IX.1978, M.M. Furniss, ex. Pseudotsuga menziesii (WFBM-6), Alder, 12 mi S.W. (WFBM-16). Park Co.: Livingston, 10 mi S.E., 23.VII.1988, M.M. Furniss, J.B. Johnson, ex. Pseudotsuga menziesii (WFBM-2). NEW MEXICO:Otero Co.: Cloudcroft, 4.VI.1969, tree 53, S.L. Wood, ex. Pseudotsuga menziesii (MSUC-2). Sierra Co.: Emory Pass, 24.VII.1974, D.E. Bright, ex. Pseudotsuga menziesii (CNCI-1). WASHINGTON: [Whitman Co.]: Pullman, 23.VI.1951, N.M. Downie (FMNH-1). WYOMING: [Teton Co.]: Jackson, A.D. Hopkins, ex. Pseudotsuga menziesii (USNM-1).

Distribution.

CANADA: British Columbia. UNITED STATES: Arizona, Colorado, Idaho, Montana, New Mexico, Washington, Wyoming (Fig. 32).

Hosts.

Pseudotsuga menziesii (Mirb.) Franco (Douglas fir).

Biology.

Scolytus fiskei colonizes suppressed limbs and branches of Pseudotsuga menziesii as well as fresh slash ( Edson 1967; Smith, pers. obs.). The adult gallery is bayonet shaped, parallel to the grain of wood and consists of two egg galleries, one below and one above the nuptial chamber and a turning niche. The female constructs the adult gallery mostly in the cambium and lightly scores the sapwood. Larval mines are perpendicular to the egg gallery and turn to form a fan shaped pattern ( Edson 1967; Furniss and Johnson 2002; Smith, pers. obs.) (Fig. 24). The adult gallery measures 3.8-9.0 cm in length ( Edson 1967). The following year adults emerge and excavate tunnels within twigs of Douglas fir for maturation feeding causing twig flagging (reported as Scolytus unispinosus McMullen and Atkins 1962).

Like most Scolytus species, there is a very limited amount of information regarding Scolytus fiskei . For many years it was considered a synonym of Scolytus unispinosus and was thus referred to as Scolytus unispinosus in publications. Very little was written about this species in the US (see Wood and Bright 1992) other than host preference and gallery descriptions ( Keen 1938; Edson 1967; Bright 1976). McMullen and Atkins (1962) reported some notes on the biology of Scolytus unispinosus in British Columbia and appear to have reported a combined account of Scolytus unispinosus and Scolytus fiskei . The authors noted the gallery of the Scolytus unispinosus studied in their investigations as "in about 15 per cent of the galleries over 20 days of age were the type described by Chamberlin and Keen [ Scolytus unispinosus , which has only a single egg gallery]; the majority were of the forked type and were similar to those of Scolytus tsugae [referencing a forked or bayonet shaped gallery that is made by Scolytus fiskei ]". Their description matches the gallery description of Scolytus fiskei , which like has two egg galleries as part of a bayonet shaped adult gallery. Because most of the specimens are of Scolytus fiskei , this article does offer some information regarding the biology of the species be used with caution because not all of the findings may apply to Scolytus fiskei .

Remarks.

The holotype of Scolytus fiskei does not bear a locality label. Blackman’s (1934) description states the holotype was collected at the Capitan Mountains, New Mexico.

Furniss and Johnson (2002) report Scolytus unispinosus from Alberta, Canada. These specimens are likely Scolytus fiskei based on the geographic distribution of the species in the Rocky Mountains.

Wood (1977: 388) placed Scolytus fiskei in synonymy with Scolytus unispinosus after examining both holotypes and 164 specimens from Arizona to British Columbia and concluded that there was too much intraspecific variation to recognize them as separate species. We assessed the intraspecific and interspecific variation (Tables 6 and 7) for each of the four genes for each species. Scolytus fiskei intraspecific variation for COI was low, 0.0-0.0231, and averaged 0.0183 among all sampled populations. Scolytus unispinosus intraspecific variation was also low, 0.0016-0.0282 and averaged 0.0121. Interspecific variation between Scolytus fiskei and Scolytus unispinosus was much higher, 0.0331-0.0521 and averaged 0.043 among populations. Similar differences were also observed with CAD (Table 7). The species have separate geographical ranges with Scolytus fiskei occurring primarily in the Rocky Mountains and British Columbia while Scolytus unispinosus occurs in the Cascade and Sierra mountains from California to British Columbia. Both species are sympatric in the Interior Plateau of British Columbia near Merritt. The species are separated by the characters listed in the diagnosis and by the galleries. The galleries of Scolytus fiskei contain two egg galleries; one above and one below the nuptial chamber. The gallery of Scolytus unispinosus only contains a single egg gallery. In addition, the gallery of Scolytus fiskei lightly scores the sapwood while that of Scolytus unispinosus deeply scores the sapwood. After examining the types, 950 specimens of both species and testing the monophyly of each species using four genes, it is apparent that Scolytus fiskei is a distinct lineage and is here removed from synonymy with Scolytus unispinosus .