Among adults without a marginal longitudinal band on the pronotum [indecisus, tarsalis and tropicalis], both sexes of X. morrisoni are recognized by the wide gena (in frontal view maximum width between the outer edges of eyes clearly less outer edges of genae), and the narrow, sharp and mainly smooth transverse ridge above the mandible. Females have black femora. Males have the width of the gena between the genal ridge and the outer edge of eye generally less than 0.5 times as wide as the maximum eye length.
Color. Head and thorax black except for small white spot behind eye extending ventrally to level of middle of eye (as in Fig. B5.35); antenna black but reddish brown in apical 0.5 (Fig. B5.30). Legs black but light reddish brown at apex of femora (metafemur almost white in basal 0.15), tibiae and tarsi (Fig. B5.28). Fore and hind wings very darkly tinted, veins black (including veins C and R, and vein 1r-rs near junction with stigma). Abdomen segments 1 or 1 and 2 black, segments 2–10 or 3–10, and apical section of sheath reddish brown.
Head. Eye in lateral view (20 specimens measured) with maximum height 1.35–1.60 times as long as maximum length, and maximum height of eye 0.49 times as long as maximum head height (from transverse ridge on gena above mandible to top of head) (as in Fig. B5.7). Gena in dorsal view with maximum distance between outer edges clearly wider than maximum width between outer edges of eyes (in frontal view, outer edges of eyes clearly not intersecting genae), and in lateral view distance between outer edge of eye and genal ridge 0.43–0.50 times as long as maximum length of eye (Fig. B5.26). Transverse ridge above mandible narrow, sharp and mainly smooth (as in Fig. B5.21). Head in dorsal view with pits restricted to vertex (from dorsoposterior edge of eye to occiput) and postocellar area (on median furrow and a little more widespread near lateral ocelli), in lateral view pits almost absent on gena ventral to genal ridge (as in Fig. B5.35), and scattered (mainly near eye) and small (diameter of pit 0.2–0.3 times ocellus diameter) between outer edge of eye and genal ridge (Fig. B5.26).
Thorax. Fore wing vein 3A presence or absence not recorded.
Abdomen. Median basin of tergum 9 with base (outlined by two lateral black longitudinal furrows) 0.7 times as wide as median length, with maximum width of basin 1.3 times as wide as median length, and basin 0.7 times as long medially as median length of cornus. Cornus constricted in dorsal view, its minimum width (at constriction) 0.8 times as wide as maximum width subapically. Sheath. Length 1.2–1.5 times as long fore wing length; basal section 0.22–0.30 times as long apical section (N = 6); lateral surface of apical section with well defined ridge (as in Fig. B5.13 see insert). Ovipositor. Lancet with 31–34 annuli (first 15 annuli very hard to see, but still outlined); junction of basal and apical section of sheaths aligned between 3rd and 4th annuli; major pits present on 5 apical annuli before teeth annuli, and at most with a very small pit on preceding annulus.
Color. Antenna, femora, tibiae and tarsi (except for reddish brown tarsomeres 3–5 or 4 and 5) black. Abdomen black on segments 1 and 2 and at side of terga 3–8, reddish brown elsewhere. Pronotum in dorsal view with brown spot on anterolateral angle.
Thorax. Metatibia with shallow notch on dorsal edge in basal 0.25.
Xeris morrisoni is similar to X. indecisus (pale abdomen form). Females of X. morrisoni are easily distinguished on leg and flagellum color and both sexes on the narrow gena. The DNA barcodes support the species level status between the two species. No specimens with intermediate structures and color pattern are known.
Xeris morrisoni has a moderately wide host range. Based on 232 reared and confirmed specimens, all are Pinaceae: Abies concolor (228; most specimen records from Kirk (1975)), Picea pungens (1), and Pseudotsuga menziesii (3). Based on other, better sampled species of this genus, we expect that this species has a wider host range than this.
Based on 13 field-collected specimens, the earliest and latest capture dates are from early June to late July.
USA: CO. Xeris morrisoni is recorded from forested regions of southwestern United States (Burks 1958, Burks 1967, Cameron 1965, Smith 1979) (Fig. C42.6).
Specimens studied and included for the distribution map: 7 females and 6 males from OSAC, UAIC, and USNM.
Specimens for molecular studies: 6 specimens. See Fig. E2.3.
USA. Colorado: 2005, CBHR 190, 658; 2005, CBHR 533, 627; 2005, CBHR 534, 658; 2005, CBHR 535, 608; 2005, CBHR 536, 658; 2005, CBHR 537, 658.