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Siricidae (Hymenoptera: Symphyta: Siricoidea) of the Western Hemisphere
CJAI 21, July, 2012
doi: 10.3752/cjai.2012.21
Nathan M. Schiff, Henri Goulet, David R. Smith, Caroline Boudreault, A. Dan Wilson, and Brian E. Scheffler

Sirex californicus (Ashmead), n. stat.

Fig. C7.1, Schiff et al. 2006: 36, 37 (female with dark legs, habitus)
Fig. C7.2 (female with pale legs, habitus)
Fig. C7.3, Schiff et al. 2006: 35 (male habitus)
Fig. C7.4 (live female with dark legs)
Fig. C7.5 (live female with pale legs)
Fig. C7.6 (live male)
Fig. C7.7 (map)

Paururus Californicus Ashmead, 1904: 64. Lectotype female (USNM), here designated; labeled “Sept.” “Placer Co., Cal.” “female Type No. 7683 U.S.N.M.”, “Paururus californicus Ashm, female [handwritten] Female, type [handwritten]”. Paralectotype female, here designated, from “Hoquiam, Wash.”; Middlekauff 1960: 63. Type locality: California, Placer Co.
Sirex californicus; Bradley, 1913: 11 (change in combination); accepted by Ries 1951: 83.
Sirex obesus Cameron, 1967: 19 (not Bradley, 1913: 12); accepted by Smith 1979: 127.
Sirex juvencus race cyaneus Bradley, 1913: 14 (not S. cyaneus Fabricius, 1781: 419); accepted as a subspecies by Ries 1951: 83, Middlekauff 1960: 65, Smith 1979: 126. This synonymy applies only to females with light reddish brown femora.
Sirex cyaneus Middlekauff, 1960: 64 (not Fabricius, 1781: 419); accepted by Smith 1979: 127. This applies to the pale legged females of S. californicus.
Sirex juvencus californicus; Benson, 1963: 252 (change in rank); accepted by Cameron 1967, Morris 1967: 60, Smith 1979: 127.

Diagnostic Combination

Among females with the completely black legs, a moderately short metatarsomere 2 (about 2 times as long as high), and a completely or partly darkly tinted (dark bands behind stigma and apical third) fore wing [obesus and nigricornis], those of S. californicus are recognized by the scattered pits on the gena and part of the vertex (pits 2.0–4.0 pit diameters apart). Among females with completely pale legs beyond the coxae, a moderately short metatarsomere 2 (about 2.0 times as long as high), and a short tarsal pad on metatarsomere 2 (about 0.5 times as long as ventral tarsal length) [noctilio], those of S. californicus are recognized by the well developed pits on the vertex and the widespread net-like pits on the median 0.7 of mesoscutum. Among males with reddish brown femora, tibiae and tarsi [mexicanus and xerophilus], those of S. californicus are recognized by the light reddish brown basal five or six antennomeres.



Color. In dark form, body, legs, palps, antenna black with dark blue metallic reflections, or in pale form, black with dark blue metallic reflections but femora, tibiae and tarsomeres 1-4 light reddish brown. Fore wing darkly tinted (southern part of range) to clear with dark bands basal to stigma and in apical third (Fig. B2.74).

Head. Gena with pits 2.0–4.0 pit diameters apart (Fig. B2.17), vertex and postocellar area with pits 0.1–2.0 pit diameters apart, and each pit diameter about 0.15–0.2 that of lateral ocellus (Fig. B2.36).

Thorax. Mesoscutum with coarse net-like pits restricted to posterior 0.6 of median area, with transverse and longitudinal ridges in coarsely pitted area. Metatarsomere 2 in lateral view more than 2.0 times as long as high, and its length about 1.2 times length of tarsomeres 3 + 4; tarsal pad about 0.5. times as long as ventral length of tarsomere. Fore wing vein 3A absent (Fig. B2.74).

Abdomen. Median basin of tergum 9 with basal width 1.1–1.4 times as long as median length, maximum width 1.3–1.7 times as long as median length, and median length 0.6–0.8 times cornus length. Cornus in dorsal view short, either with edges straight in large specimens or clearly angular midway in small specimens, its median length 0.8–1.1 as long as maximum width of abdomen at junction of terga 9 and 10. Sheath. Length 0.7–0.8 times as long as fore wing length, basal section 1.05–1.35 times as long as apical section. Ovipositor. Lancet with 28–38 annuli (edge of basal annuli difficult to see); junction of basal and apical section of sheath aligned between 12th and 13th to 15th and 16th annuli, with 24–34 pits beginning with annulus 2; pit of annulus 2 only extending to edge of annulus 1 (Fig. B2.25). Pits near middle annuli (Fig. B2.19) or area at base of apical section of sheath 0.3–0.35 times as long as an annulus (pits clearly decreased at base to about 0.2), about 0.4–0.6 times as high as lancet height in lateral view, and about 1.6–2.2 times as long as high (Fig. B2.38, middle); length of lancet annulus/ovipositor diameter (lance + lancet) for annulus 2 1.43–2.07, for annulus 5 1.46–2.14, for annulus 10 1.3–1.8, and for annulus 13 1.40–1.66 (7 specimens). Last 4 or 5 annuli before teeth annuli and as well as first tooth annulus with ridge on ventral edge of pit (Fig. C1.15). Edge of apical 4-5 annuli before teeth annuli extending as ridge to ventral edge of lancet.


Color. Head, apical 0.7 of antenna, palps, thorax, abdominal segments 1, median area of tergum 2, or 1 and 2 and median area of tergum 3 black with dark blue metallic reflections; abdominal segments 3-10, and antennomeres 1–5 light reddish brown (Fig. B2.113). Legs reddish brown, but black on coxae (Fig. B2.107). Fore wing clear with a very light yellow tint in some specimens (Fig. B2.115).

Thorax. Metatibia 3.8-4.3 times as long as maximum width. Metatarsomere 1 in lateral view 2.7-3.1 times as long as maximum height (Fig. B2.107).

Taxonomic Notes

Benson (1963) ranked S. californicus as a subspecies of the European S. juvencus. The two populations differ in color pattern in both sexes (the color pattern of males was unknown to Benson at the time); in females of S. californicus, the tarsal pad of metatarsomere 2 is short (long in S. juvencus) and the ovipositor pits are long and large medially and about twice as long as high (short and small medially and a little longer than high in S. juvencus). The main hosts of S. californicus are various species of Pinus; for S. juvencus they are various species of Picea. The range of S. californicus extends from southernmost British Columbia and southwestern Alberta to California, Colorado and South Dakota; a Holarctic species would not have such a range in the Nearctic region. Therefore, S. californicus is clearly and specifically distinct from S. juvencus.

Females of S. californicus exist in two discrete color forms. The legs are either all black or they are light reddish brown beyond the coxae. Dark-legged females are the most common form seen over the range. Pale-legged females are known from southern British Columbia and the northern half of western United States as far east as the Black Hills of South Dakota.

Females of S. californicus with black legs are similar to three other western species: S. obesus, S. mexicanus, and S. xerophilus. They are distinguished from them by the less dense pits on the vertex. They are also distinguished from S. mexicanus and S. xerophilus by the partial or complete dark tinted wings and differences in the pit development on the ovipositor, and from the very similar S. obesus by the more slender metatarsomere 2. Females of S. californicus may also be confused with females of the black abdomen form of S. nigricornis (if the British Columbia record for this species is correct). The ovipositor pits are longer and the pit density on the vertex is clearly less in S. californicus than in S. nigricornis.

Females of S. californicus with pale legs may be confused with similarly colored species associated with firs and spruces (e.g., S. abietinus, S. cyaneus, S. nitidus, and very few specimens of S. varipes). Pits on the head of S. californicus are clearly larger and the tarsal pad on metatarsomere 2 shorter than in the above four species. Females of the pale form of S. californicus may be confused with those of S. noctilio with short tarsal pads on metatarsomere 2, but they are easily distinguished by the much larger and denser pits on the vertex.

Males of S. californicus from westernmost Nevada were first associated with females and described by Cameron (1967), and are easily distinguished from males of the three other species with a reddish brown metafemur.

Biological Notes

Cameron (1967) reported 216-804 eggs in female ovaries of S. californicus, with the highest number of eggs associated with the largest females. Eggs that are going through the ovipositor become 2.5 times as long as those within the ovaries (Cameron 1967). Megarhyssa nortoni nortoni (Cresson), an important parasitoid, was often observed ovipositing in logs of Pinus jeffreyi containing larvae of S. californicus (Cameron, 1967).

Hosts and Phenology

The host range of S. californicus is wide (Essig 1926, Middlekauff 1960, Cameron 1965, Cameron 1967, Morris 1967, Kirk 1975 [some of the reared specimens could be S. obesus]). The most commonly seen hosts belong to Pinus (99% of reared specimens). Based on 128 reared and confirmed specimens, all hosts are Pinaceae: Larix occidentalis (1), Pinus albicaulis (1), P. contorta (107) (pale legged females reported as S. juvencus by Morris (1967)), P. coulteri (1), P. jeffreyi (3), P. lambertiana (11), P. monticola (1), P. ponderosa (336) (large emergence reported by Cameron (1968) and Kirk (1975)), P. sylvestris (2), and Pseudotsuga menziesii (1). We have only one record from Cupressus macrocarpa (Cupressaceae).

Based on 74 field-collected specimens, the earliest and latest capture dates are July 17 and September 11. The main flight period is from second half of July to second half of September with a peak in late August (Cameron 1967).


CANADA: AB, BC. MEXICO: Intercepted specimen from Mexico at United States border in southern California. USA: CA (Middlekauff 1960), CO, ID, MT, NV, OR, SD, UT, WA, WY. Sirex californicus is found from the Rocky Mountains of southern British Columbia to California, Colorado and South Dakota (Fig. C7.7). We have seen one intercepted female from New Zealand.

Specimens studied and included for range map: 384 females and 91 males from BDUC, BYUC, CFIA, CNC, MTEC, NFRC, OSAC, PFRC, USFS–GA, and USNM.

Specimens of S. californicus for molecular studies: 52 specimens. See Fig. E2.5f.

CANADA. British Columbia: 2006, CBHR 415, 658; 2006, CBHR 416, 658; 2006, CBHR 417, 658; 2006, CBHR 421, 601; 2006, CBHR 422, 624; 2006, CBHR 424, 658; 2006, CBHR 426, 621; 2006, CBHR 427, 658; 2006, CBHR 428, 658; 2006, CBHR 429, 658; 2006, CBHR 430, 658; 2006, CBHR 431, 658; 2006, CBHR 432, 658; 2006, CBHR 434, 617; 2006, CBHR 435, 658; 2006, CBHR 436, 658; 2006, CBHR 437, 658; 2006, CBHR 447, 658; 2006, CBHR 473, 658; 2000, SIRCA 075, 587; 2000, SIRCA 077, 636. USA. California: 2007, CNCS 1020, 590. Colorado: 2005, CBHR 191, 658; 2006, CBHR 407, 607. Idaho: 2008, CBHR 1355, 624; 2008, CBHR 1359, 658. Montana: 2004, CBHR 207, 658; 2007, CNCS 1001, 609; 2007, CNCS 1002, 603; 2007, CNCS 1003, 557; 2007, CNCS 1004, 610; 2007, CNCS 1009, 604; 2007, CNCS 1010, 611. Oregon: 2004, CBHR 521, 658. Washington: 2005, CBHR 233, 602; 2007, CBHR 1184, 658; 2007, CBHR 1185, 658; 2007, CBHR 1186, 658; 2007, CBHR 1187, 658; 2007, CBHR 1243, 658; 2008, CBHR 1330, 580; 2008, CBHR 1341, 643; 2008, CBHR 1343, 658; 2008, CBHR 1344, 624; 2008, CBHR 1347, 630; 2008, CBHR 1349, 514; 2008, CBHR 1350, 658; 2008, CBHR 1970, 658. Unknown state: 2006, CBHR 402, 658; 2006, CBHR 403, 658; 2006, CBHR 404, 601; 2006, CBHR 405, 630; 2006, CBHR 406, 658.

Specimens of S. sp. near californicus for molecular studies: 9 specimens. See Fig. E2.5f.

USA. Colorado: 2007, CNCS 1006, 585; 2007, CNCS 1007, 605; 2007, CNCS 1008, 609; 2007, CNCS 1013, 588; 2007, CNCS 1014, 619; 2007, CNCS 1015, 603; 2007, CNCS 1016, 584; 2007, CNCS 1018, 608; 2007, CNCS 1019, 608.