ISSN 1911-2173
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

4. Xeris cobosi Viedma and Suarez (new status)

Fig. C4.1 (female habitus, dorsal)

Fig. C4.2 (female habitus, lateral)

Fig. C4.3 (female habitus, ventral)

Xeris spectrum cobosi Viedma and Suárez, 1961: 20. Holotype female (MNCN), images of type kindly prepared by Mercedes Paris were examined. Specimen labels: “Tizi – Ifri, Rif, Coll. A Cobos/VII-1960”; Type number “2055”; MNCN number “50762”. Type locality, Morocco, Tizi-Ifri. Type complete except right metatarsomeres 2–5 missing. Smith, 1978: 85 (catalog).

Diagnostic combination

Among specimens without a marginal lateral stripe on the pronotum (pronotum black), dense and numerous pits on vertex between dorsal edge of eye and occiput outside postocellar area, and black abdomen [cobosi, himalayensis and some indecisus], X. cobosi is recognized in the female and probably the male by the short setae of frons and clypeus (setae 0.6–0.7 times as long as the diameter of lateral ocellus) and clear fore wing, and in the female by the black flagellum and the light reddish-brown coxae.



Color. Head black with white spot on gena dorsal to middle of eye, the white spot very small and not extending to genal ridge (Fig. C4.4); antenna black; last maxillary palpomere black. Thorax black with very small and indistinct brown spot in anterolateral angle of pronotum (Fig. C4.2). Legs beyond coxae light reddish brown (Fig. C4.2), coxae mainly light reddish brown (partly black on procoxa outer surface toward base) (Fig. C4.3). Fore wing clear except for lightly tinted band in apical 0.25 and on posterior corner of cells 2CU and 3CU (Fig. C4.1); costal cell yellowish brown (as in Fig. B2.39); most of area ventral to anal cells yellowish brown; veins black (including veins C, R, and base of stigma on both sides of junction with vein 1r-rs) (Fig. C4.1). Abdomen black (Fig. C4.1). 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 about as long as the diameter of a lateral ocellus (Fig. C4.4). Eye in lateral view (N = 1) with its maximum height 1.40 times as long as its maximum length (as in Fig. C4.4), and maximum height of eye 0.42 times as long as maximum height of head (from transverse ridge on gena above mandible to top of head) (Fig. C4.4, 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 (Fig. C4.5) (in frontal view outer edges of eyes clearly not intersecting genae, as in Fig. B2.5); in lateral view with distance between outer edge of eye and genal ridge 0.55 times as long as maximum length of eye (Fig. C4.4, measurements as in Fig. B2.77), with few or no pits ventral to genal ridge (Fig. C4.4), and with many medium size pits (diameter of pit 0.2 times lateral ocellus diameter) between outer edge of eye and genal ridge (mainly near eye) (Fig. C4.4). Transverse ridge above mandible narrow, sharp and mainly smooth (as in Fig. B2.18). Vertex densely pitted and pits medium in size (diameter of pit 0.2–0.3 times lateral ocellus diameter), pits present from dorsoposterior edge of eye to occiput outside postocellar area, absent on most of postocellar area (Fig. C4.5); pits scattered and medium in size along most of median furrow but more widespread near lateral ocelli (Fig. C4.5).

Thorax. Pronotum in lateral view with coarse polygonal pits on about 0.7 of posterior surface (as in Fig. B2.97). Propleuron in lateral ventral view (not seen in images). Transcutal furrow of mesonotum clearly outlined and finely sculptured, thus mesoscutum and axilla clearly distinct (as in Fig. C5.2). Fore wing in middle 0.3 of vein 2A diverging considerably away from wing edge (as in Fig. C12.6) and then not abruptly curved away from wing edge (as in Fig. C12.6); vein 3A reduced to a stump (N = 1).

Abdomen. Tergum 9 on ventral half below and above longitudinal furrow near center (meshes of microsculpture not seen in image); median basin with base (outlined by two lateral black longitudinal furrows; N = 1) about 0.7 times as wide as its median length, with maximum width of basin about 1.35 times as wide as its median length and basin about 0.52 times as long medially as median length of cornus (Fig. C4.1, measurements as in Fig. A3.2). Cornus constricted in dorsal view, its minimum width (at constriction) about 0.8 times as wide as maximum width subapically (Fig. C4.1); with large teeth in apical 0.3 (as in Fig. B2.110). Sheath. Basal section 0.36 times as long as apical section (N = 1) (Fig. C4.2); lateral surface of apical section with well-defined ridge (as in Fig. B2.13, insert); total length 1.2–1.4 times as long as fore wing length. Ovipositor. Not dissected out in image.



Taxonomic notes

Our recognition of Xeris cobosi is based on images of the holotype. In the female (and probably the male), the head sculpture, the color pattern of cell C and stigma at its base on both sides of junction with vein 1r-rs, and flagellum color suggest this species is close to X. himalayensis. The female is distinguished from females of X. himalayensis by the short setae on frons and clypeus (probably applies in the male) and by mainly reddish-brown coxae.

Hosts and phenology

The host of X. cobosi is not certain. However, Viedma and Suárez (1961) mentioned that Cedrus atlantica and Abies pinsapo maroccana were the main conifers at the site. Pruja (1959) captured one female from a fir forest (A. pinsapo maroccana) at Talasse N’Tane (altitude 1800 m), Morocco, in early July. We did not see the female captured by Pruja (1959), but its description matches that of X. cobosi (genal spot small, no lateral pale bands on the pronotum, and black veins on fore wing), not X. spectrum.

The single female was captured in July, 1960, by A. Cobos.


Morocco: Tizi-Ifri (holotype); Talasse N’Tane.

Specimen studied: Images of the female holotype from MNCN

Adults of X. indecisus have two distinct color forms: the abdomen is either mainly reddish brown or completely black. Both color forms are known from the coastal and interior regions of British Columbia south to California. We cannot recognize any geographical variation pattern between these two color forms.

Less obvious are variations in ovipositor length. The basal section of the sheath is proportional to body size, but the apical section is not. We calculated the ratio between the basal and apical section as a general measure of relative size for the ovipositor. Females (N = 10) from Lake Tahoe, California, have a ratio of 0.20–0.25 (mean = 0.23). In Oregon and British Columbia, females (N = 44) have ratios of 0.20– 0.32 (average 0.25). Therefore specimens from California have a relatively longer apical section of the sheath. DNA barcodes based on 21 specimens from regions with long and short ovipositors do not segregate specimens into two groups. We see no reasons to recognize subspecies.

However, in the central Rocky Mountain region, there are no specimens of X. indecisus with a black abdomen. All specimens have a reddish-brown abdomen and wings of females are darkly tinted. We do not want to officially recognize this population as subspecifically distinct because the sample is rather small and the females of this species and X. degrooti cannot be recognized except by their DNA barcodes.

Hosts and phenology

Xeris indecisus has a wide host range (Bedard 1938 – under X. morrisoni, Cameron 1965, Morris 1967). Based on 121 reared and confirmed specimens, all but one host are Pinaceae: Abies sp. (13), A. concolor (17), A. grandis (10), A. lasiocarpa (8), A. magnifica, Larix occidentalis (12), Picea sp. (1), P. sitchensis (10), Pinus contorta (2), P. ponderosa, Pseudotsuga menziesii (28),and Tsuga heterophylla (20). There is only one record from Calocedrus decurrens (Cupressaceae).

Based on 24 field-collected specimens, the earliest and latest capture dates are May 18 and September 11. The main flight period is from the first half of June to the first half of September.


Canada: Britsh Columbia. United States: California, Colorado, Idaho, Montana, Nevada, Oregon, South Dakota, Utah, Washington. Xeris indecisus, a widespread western species in forested regions, is recorded from British Columbia, Montana, and South Dakota to California, Arizona and Colorado(Burks 1967, Cameron 1965, Smith 1979) (see map C42.6 in Schiff et al. 2012). The specimens of X. indecisus recorded by Burks (1967) under X. spectrum townesi from Arizona need confirmation as they could be specimens of X. chiricahua. One female from the west coast of the United States was intercepted in Osaka, Japan (Okutani 1965). We have seen a female intercepted in New Zealand (FRNZ and PANZ) and one more intercepted at Slough (near Windsor, England) as an infestation in a control laboratory (BMNH).

Specimens studied and included for distribution map: 234 females and 113 males BYUC, CFIA, CNC, DEBU, EDUM, MTEC, OSAC, PFRC, ROME, UASM, UCRC, USFS–GA, USFS–MS, and USNM.

Specimens for molecular studies: 29 specimens from Canada (British Columbia) and United States (California, Colorado, Oregon and Washington). See Fig. D1.2c. For each specimen the following is recorded: country, year, state/province, specimen code (in italics), and number of base pairs.

CANADA. British Columbia: 2006, CBHR 418, 658; 2006, CBHR 419, 658. USA. California: 1999, CBHR 33, 658; 1999, CBHR 98, 658; 2007, SIR 075, 421; 2007, SIR 076, 600; 2007, SIR 077, 586; 2007, SIR 078, 654. Colorado: 2005, CBHR 189, 658. Oregon: 1999, CBHR 108, 658; 2006, CBHR 385, 658; 2006, CBHR 1078, 658; 2007, SIR 074, 421; 2007, SIR 080, 615; 2007, SIR 081, 421. South Dakota: 2007, CNCHYM 02489, 422; 2007, CNCHYM 02493, 422; 2007, CNCHYM 02492, 129; 2007, CNCHYM 03050, 410; 2007, CNCHYM 03051, 374. Utah: 2008, CNCHYM 03047, 382. Washington: 2005, CBHR 210, 658; 2005, CBHR 215, 658; 2005, CBHR 216, 658; 2005, CBHR 228, 658; 2005, CBHR 235, 658; 2005, CBHR 239, 658; 2005, CBHR 254, 658; 2008, CBHR 1310, 658.