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Revision of the World species of Xeris Costa (Hymenoptera: Siricidae)
CJAI 28 -- September 25, 2015
doi: 10.3752/cjai.2015.28
Henri Goulet1, Caroline Boudreault1 and Nathen M. Schiff2

10. Xeris morrisoni (Cresson)

Fig. C10.1, (female habitus); Schiff et al. 2006: 88, 89

Fig. C10.2, (male habitus); Schiff et al. 2006: 87

Urocerus morrisoni Cresson, 1880: 35. Lectotype female (ANSP), designated by Cresson (1916), examined by D. R. Smith and H. Goulet. Type locality: “Colorado”. Harrington, 1893: 149; Cresson, 1916: 10 (notes about type from Colorado).

Sirex morrisonii; Kirby, 1882: 382 (change in combination and spelling). Dalla Torre, 1894: 390.

Xeris morrisoni; Ashmead, 1898: 180 (change in combination). Konow, 1898a: 74, 83; Howard, 1901: pl. 14, fig. 36; Konow, 1905b: 125, 126; Konow, 1905a: 9 (catalog); Bradley, 1913: 22, 23, 24; Hedicke, 1938: 23 (catalog); Benson, 1943: 30, 31 (measurements); Ries, 1951: 84 (catalog, Hosts); Furniss & Carolin, 1977: 454, 457 (host and range);  Schiff et al., 2012: 263.

Urocerus tarsalis; synonymy by Konow, 1898a: 88 (not Cresson, 1880: 35). Bradley, 1913: 24; Ries, 1951: 84.

Urocerus indecisus; synonymy by Konow, 1898b: 226 (not MacGillivray, 1893: 243). Bradley, 1913: 24; 1951: 84.

Xeris morrisoni morrisoni; Maa, 1949: 80, 83–85 (change in rank) (hosts). Burks, 1958: 17 (catalog and hosts); Cameron, 1965: 15 (hosts); Burks, 1967: 27 (new state record); Kirk, 1975: 57–58 (host); Smith, 1979: 129 (catalog and hosts); Taeger et al., 2010: 105 (catalog).

Diagnostic combination

Among adults with reddish-brown abdomen and without marginal stripe on the lateral margin of the pronotum [morrisoni, degrooti, indecisus, tarsalis and tropicalis], X. morrisoni is recognized in both sexes by the wide gena (in frontal view maximum width between the outer edges of eyes clearly less than outer edges of genae), and the narrow, sharp and mainly smooth transverse ridge above the mandible, in females by the black femora, and in males by the narrow width of the gena between the genal ridge and the outer edge of eye that is less than 0.5 times as wide as the maximum eye length.



Color. Head black except for a large white spot on gena dorsal to middle of eye extending down to genal ridge (Fig. B2.76); flagellum black in basal 0.3–0.5 but reddish brown in apical 0.5–0.7 (Fig. B2.73); last maxillary palpomere reddish brown (Fig. B2.76). Thorax completely black or with small to large white spot on vertical surface near anterolateral angle of pronotum (spot very narrow if visible in dorsal view) (as in Figs. B2.54). Legs light reddish brown except for black coxae, trochanters and femora (Fig. C10.1). Fore and hind wings darkly tinted brown (Fig. C10.1); costal cell brown; veins dark brown or black (including veins C and R, and base of stigma around junction with vein 1r-rs). Abdomen segments 1 or 1 and 2 black, and segments 2–10 or 3–10 reddish brown (Fig. C10.1 and as Fig. B2.60). Sheath with apical section black and basal section reddish brown.

Head. Distance between nearest eye edge and lateral ocellus edge about 1.1–1.5 times as long as distance between inner edges of lateral ocelli (as in Fig. C1.5). Setae on clypeus 0.6–0.7 as long as diameter of a lateral ocellus (Fig. B2.76). Eye in lateral view (N = 20) with maximum height 1.35–1.60 times as long as its maximum length (Fig. B2.76), and maximum height of eye 0.42–0.51 times as long as maximum height of head (from transverse ridge on gena above mandible to top of head, measurements as in Fig. B2.8). Gena in dorsal view with maximum distance between outer edges clearly wider than maximum distance between outer edges of eyes (as in B2.41) (in frontal view outer edges of eyes clearly not intersecting genae, measurements as in Figs. B2.5); in lateral view with distance between outer edge of eye and genal ridge 0.43–0.50 as long as maximum length of eye (Fig. B2.76), with almost no pits ventral to genal ridge, and with many medium size pits (diameter of pit 0.2–0.25 times lateral ocellus diameter) between outer edge of eye and genal ridge pits (mainly near eye) (Fig. B2.76). Transverse ridge above mandible narrow, sharp and mainly smooth (Fig. B2.76). Vertex quite densely pitted and pits medium in size (diameter of pit about 0.3 times lateral ocellus diameter), pits present from dorsoposterior edge of eye to occiput outside postocellar area, absent on most of postocellar area (as in B2.41); pits dense, narrowly distributed and medium in size along all median furrow (not sharply outlined), but a little more widespread near lateral ocelli (as in B2.41).

Thorax. Pronotum in lateral view with coarse polygonal pits on 0.3–0.7 of posterior surface (as in Fig. B2.97). Propleuron in lateral view with medium size polygonal pits on most of disc (as in Fig. C12.7); in ventral view with scattered to moderately dense small teeth with smooth surface in between (as in Fig. B2.22). Fore wing in middle 0.3 of vein 2A diverging very rarely slightly (as in Fig. C11.6) to usually considerably (as in Fig. C12.6) away from wing edge and then more (as in Fig. C11.6) or less (as in Fig. C12.6) abruptly curved away from wing edge; vein 3A absent.

Abdomen. Tergum 9 with meshes of microsculpture on ventral half below and above longitudinal furrow near center not well impressed and sculpticells clearly flat (slightly raised as scale above furrow) (as in Fig. B2.93, insert); median basin with base (outlined by two lateral black longitudinal furrows) 0.7 times as wide as its median length, with maximum width of basin 1.3 times as wide as its median length, and basin 0.7 times as long medially as median length of cornus (measurements as in Fig. A3.2). Cornus constricted in dorsal view, its minimum width (at constriction) 0.8 times as wide as maximum width of cornus subapically; with large teeth in apical 0.3 (as in Fig.B2.110). Sheath. Basal section 0.22–0.30 times as long as apical section (N = 6) (Fig. C10.1); lateral surface of apical section with well-defined ridge (as in Fig. B2.13, insert); length 1.2–1.5 times as long as fore wing length. Ovipositor. Lancet with 31–34 annuli (first 15 annuli difficult to see, but still outlined; N = 3); junction of basal and apical sections of sheath aligned between 3rd– 4th annuli; major pits present on last 4–6 apical annuli before teeth annuli, and with or without a very small pit on preceding annulus (as in Fig. C1.18).


Color. Head with dorsal spot behind eye similar in size to female. Antenna, coxae, femora, tibiae and tarsi (except reddish-brown tarsomeres 3–5 or 4 and 5) black (Fig. C10.2). Pronotum in dorsal view black or with white spot on anterior angle (Fig. C10.2). Abdomen black on segments 1 and 2 and laterally on terga 3–8, and reddish brown elsewhere (Fig. C10.2).

Thorax. Metatibia with shallow notch on dorsal edge in basal 0.25 (as in Fig. B2.68).

Taxonomic notes

Xeris morrisoni is similar to X. indecisus (pale abdomen form) and X. degrooti. The DNA barcodes support the species level status of these species. No specimen has intermediate structures and color patterns between X. morrisoni and the above species. Xeris morrisoni has been found sympatrically with X. chiricahua and either or both X. degrooti and X. indecisus.

Hosts and phenology

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.

Based on 13 field-collected specimens, the earliest and latest capture dates are from early June to late July.


Mexico: Chihuahua (Ocampo Sierra La Magdelena), Durango (Guanacevi, Ej. Toro, C. Barajas). United States: Arizona, Colorado. Xeris morrisoni is recorded from forested regions of southwestern United States (Burks 1958, Burks 1967, Cameron 1965, Smith 1979) and from the Sierra Madre Occidental of Mexico between 2,700 to 3,100 m. (for United States localities see map 42.6 in Schiff et al. 2012).

Specimens studied: 1 females and 6 males from INIFAP, OSAC, UAIC, and USNM.

Specimens for molecular studies: 6 specimens from United States (Colorado) (Schiff et al. 2012). See Fig. D1.2b. For each specimen the following is recorded: country, year, state/province, specimen code (in italics), and number of base pairs.

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.

Table of contents Abstract Introduction Materials and Methods Biology Hosts Parasitoids Morphology Key DNA References Citation Appendices PDFs