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



5. Xeris degrooti Goulet, n. sp.


Fig. C5.1, (female habitus)


Type material


Holotype female (USNM) right mesotarsus missing (used for DNA extraction) otherwise in perfect condition; labelled [White with black frame] “29 May – 18 Aug 2008 Meade Co [not actually this county, see below] SD K Allen 5 EA E09”; [Blue] “SIR 158”; [Red] “HOLOTYPE Xeris degrooti H. Goulet, 2011”. Type locality: USA. SD, Pennington Co [the site is about 100 m south of Meade Co in Pennington Co.], 44.140˚N 103.436˚W.


Paratypes. South Dakota: Pennington Co., 44.140˚N 103.436˚W 29.V−18.VIII.2008. (4F, CNC and USNM).

Diagnostic combination


Among adults with reddish-brown abdomen and without marginal stripe on the lateral margin of the pronotum [degrooti, indecisus, morrisoni, tarsalis and tropicalis], X. degrooti is recognized in both sexes by the wide gena (in frontal view maximum width between the outer edges of eyes clearly less than maximum width between genae), the narrow, sharp and mainly smooth transverse ridge above the mandible, the moderately wide gena relative to eye length, and in the female the darkly tinted wings. However, females and males of X. degrooti from the central Rocky Mountain region can only be distinguished from those of X. indecisus by their DNA barcodes.






Color. Head black except for large white spot on gena dorsal to middle of eye extending down to genal ridge (as in Fig. B2.46); flagellum light reddish brown (as in Fig. B2.63); last maxillary palpomere reddish brown. Thorax completely black (as in Fig. B2.57) or pronotum with small diffused yellowish-white spot on vertical surface below anterolateral angle of pronotum, or uncommonly with a very narrow spot on anterolateral angle visible dorsally (as in Fig. B2.54). Legs light reddish brown except for coxae (Fig. C5.1); coxae almost all light reddish brown except on surface at dorsal angle (as in Fig. C7.1). Fore and hind wings darkly tinted brown (Fig. B2.65); costal cell brown; veins dark brown or black (including veins C and R, and base of stigma around junction with vein 1r-rs) (Fig. C5.1). Abdomen segments 1 or 1 and 2 black, and segments 2–10 or 3–10 reddish brown (pale form) (Fig. C5.1). 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 diameter of a lateral ocellus (as in Fig. B2.47). Eye in lateral view (N = 18) with its maximum height 1.23–1.62 times as long as its maximum length (as in Fig. B2.77), and maximum height of eye 0.43–0.50 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 Fig. B2.41) (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 0.53–0.70 times as long as maximum length of eye (as in Fig. B2.77), with almost no pits ventral to genal ridge, and with many medium size pits (diameter of pit 0.2–0.3 times lateral ocellus diameter) between outer edge of eye and genal ridge (mainly near eye) (as in Fig. B2.77). Transverse ridge above mandible narrow, sharp and mainly smooth (as in Figs. B2.18 and B2.46). 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 Fig. B2.44); 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 Fig. B2.44).


Thorax. Pronotum in lateral view with coarse polygonal pits absent or at most on 0.1 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). Transcutal furrow of mesonotum clearly outlined  and finely sculptured, thus mesoscutum and axilla clearly distinct (Fig. C5.2). 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 (75%), reduced to a stump (25%), but not extending slightly as a nebulous vein or along posterior margin of wing.


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) 0.7–1.0 times as wide as its median length, with maximum width of basin 1.3–1.7 times as wide as its median length, and basin 0.5 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 0.20–0.31 times as long as apical section (N = 40) (Fig. C5.1); lateral surface of apical section with well-defined ridge (as in Fig. B2.13, insert); total length 1.2–1.5 times as long as fore wing length. Ovipositor. Lancet with 25–30 annuli (first 15 annuli difficult to see, but still outlined; N= 15); junction of basal and apical sections of sheath aligned between 2nd  and 3rd annuli or occasionally 3rd annulus; major pits present on last 4–6 apical annuli before teeth annuli, and with a very small pit on at most each of the 6 preceding annuli (as in Fig. C1.18 with few or no small pits).


MALE. Not recognized.


Taxonomic notes


Early in our study, we examined some females from the Central Rocky Mountain region which were very similar in color pattern to those studied from along the Cascades and the coastal regions from southern British Columbia to California in the Sierra Nevada. However, in the Central Rocky Mountain region there were no specimens with a black abdomen, and all females had darkly tinted wings. We interpreted this difference as geographical variation, but we did not create a subspecies for the central Rocky Mountain population (Schiff et al. 2012).


We then received a large sample from the Black Hills in North Dakota and sent some specimens for sequencing. The first two sequences obtained had a barcode (12%) amazingly distinct from X. indecisus. We suspected contamination of the samples so more specimens of this sample were sent. To our surprise we got three more sequences of the new type and seven sequences of X. indecisus. With a 12% difference in their barcode, we assumed that structural differences could be found, but after intensive work we failed to find any differences. We have barcodes for five specimens recognizable as the new sequence, for seven specimens of X. indecisus from the same locality, and for 21 specimens of X. indecisus from coastal and southern British Columbia and California in the Sierra Nevada. The differences between significant base pairs (about 60) of these two species were consistent across the 658 based pairs.


We can distinguish X. degrooti from all specimens of X. indecisus with black abdomen, and from all females of X. indecisus with reddish-brown abdomen but with mainly clear wings. However, we cannot distinguish X. degrooti from females of X. indecisus with reddish-brown abdomen and darkly tinted wings, or males with a reddish-brown abdomen. Because barcodes distinguish both species unequivocally, we recognize X. degrooti as a species distinct from X. indecisus.


We have seen males and females from Arizona (Coconino Co., North Rim (4 F, 3 M, BYUC)) and Utah (Panguitch [Hopkins # 45296] (4 F, 1 M, USNM); Summit Co., 26 Jun – 18 Sep 2008 S. Munson 65SD E15 (1 F, CNC); Bunnels Fork (1 F, BYUC); Provo environ (1 F, BYUC); Tmpanogas near Provo (5 F, BYUC)). We suspect that they could be X. degrooti, but could not certify their identity.

Origin of specific epithet


The name degrooti is in honor of the late Peter de Groot (Canadian Forest Service, Sault Ste. Marie, Ontario, Canada) who made significant contributions towards a better understanding of the Siricidae and helped us generously in our work on the New World Siricidae by sending us numerous live and preserved specimens.


Hosts and phenology


The host is unknown, but Pinus ponderosa is numerous at the type locality. We suspect that the host range may be similar to that of X. indecisus.


Specimens were trapped between May 29 and August 18.




United States: South Dakota. Xeris degrooti is a western species in forested areas of South Dakota and possibly occuring in Arizona and Utah in the central and southern Rocky Mountains.


Specimens studied: 5 females a CNC and USNM.


Specimens for molecular studies: 5 specimens. 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. South Dakota: 2007, SIR 155, 486; 2007, SIR 158, 658; 2007, CNCHYM 02488, 539; 2011, CNCHYM 02491, 227; 2007, CNCHYM 03056, 164.

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.