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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

17. Xeris xylocola Goulet, n. sp.

Fig. C17.1 (female habitus)

Fig. C17.2 (male habitus)

Type material

Holotype. Female (OLML), in perfect condition , labelled [White] “ LAO, Hua Phan Prov. Ban Salui; Phou Pan-Mt 20˚13’30”N / 103˚59’26”E GPS 1350-1900m, 06.05.2010 Leg. C. Holzschuh + locals”; [Red] “HOLOTYPE  Xeris xylocola ♀ H. Goulet, 2015”.
Paratypes (3 females and 1 male). Same locality as holotype except for collecting date. 28-29.iv.2010 (1F, OLML); 19.v.2011 (2M, OLML); 28.v.2011 (1M, OLML); 15-16.v.2012 (1F, OLML). 

Diagnostic combination

Among specimens with a light yellow fore wing cell C and with short setae on the head [malaisei, pallicoxae, spectrum, and xanthoceros], X. xylocola is distinguished in both sexes by the narrow shiny surface medially on the pronotum and the widespread coarse pits on most of the lateral surface of the pronotum, in females by the light reddish-brown spot above and below the anterolateral corner of the pronotum, and the reddish-brown flagellum beyond flagellomere 7–10,  and in males by the well outlined yellowish-white spot extending on both sides of the genal ridge (spot basically comma-like).



Color. Head black except for white spot (rarely missing) on gena dorsal to middle of eye; white spot not clear, or not clearly outlined and ventral edge not extending to genal ridge (Fig. B2.103); scape and pedicel black, flagellomere 1–7 or 1–10 black and following flagellomeres light reddish brown; last maxillary palpomere black (Fig. B2.116). Thorax black except for yellowish-white band on pronotum along margin and below anterolateral corner (Fig. B2.125). Fore wing clear except for lightly tinted band in apical 0.25, and near junction of veins CU and 2 cu-a (as in Fig. B2.67); cell C very light yellow (paler in old specimens) (as in Fig. B2.40); most of area ventral to anal cells yellowish brown; veins black but white at base of stigma on both sides of junction with vein 1r-rs (as in Fig. B2.40). Sheath with apical section black and basal section reddish brown.

Head. Distance between nearest eye edge and lateral ocellus edge about 1.5–1.9 times as long as distance between inner edges of lateral ocelli (as in Fig. B2.20). Setae on frons and clypeus 0.6–0.7 as long as as long as diameter of a lateral ocellus (Fig. B2.103). Eye in lateral view (N = 4) with its maximum height 1.29–1.54 times as long as its maximum length (Fig. B2.103), and maximum height of eye 0.50–0.53 times as long as maximum height of head (from transverse ridge on gena above mandible to top of head) (Fig. B2.103), measurements as in Fig. B2.8). Gena in dorsal view with maximum distance between outer edges a little wider than maximum distance between outer edges of eyes (as in Fig. B2.43) (in frontal view outer edges of eyes not intersecting genae) (Fig. C17.5 and as in Fig. B2.5); in lateral view with distance between outer edge of eye and genal ridge 0.35–0.42 times as long as maximum length of eye (Fig. B2.103, measurements as in Fig. B2.77), with few or no pits ventral to genal ridge, and with very small to moderate size pits (diameter of pit 0.15–0.2 times lateral ocellus diameter) between outer edge of eye and genal ridge (mainly near eye) (Fig. B2.103). Transverse ridge above mandible narrow, sharp and mainly smooth (Fig. B2.103). Vertex scarcely pitted and pits medium in size (diameter of pits 0.2–0.25 times lateral ocellus diameter), pits present from dorsoposterior edge of eye to occiput outside postocellar area, absent on most of postocellar area, pits dense and medium in size along all of clearly outlined and gutter-like median furrow but a little more widespread near lateral ocelli (as in Fig. C17.4).

Thorax. Pronotum in dorsal view along lateral margin with irregular ridges between large teeth (as in Fig. B2.95) and in lateral view with coarse polygonal pits on almost all of surface (Fig. B2.125). Propleuron in lateral view with small polygonal pits over most of surface (as in Fig. C12.7); in ventral view generally with dense medium sized teeth often fused laterally with other teeth, with smooth or shallowly meshed surface in between (as in Fig. B2.22). Transcutal furrow of mesonotum obscured by coarse pits, thus mesoscutum and axilla apparently fused (Fig. C17.3). Metanotum with surface posterior to cenchrus and lateral 0.5 of metascutellum coarsely pitted (pit 0.1–1.5 times as wide as diameter of lateral ocellus) (Fig. B2.105). Fore wing in middle 0.3 of vein 2A diverging considerably (as in Fig. C12.6) away from wing edge, and then less (as in Fig. C12.6) abruptly curved away from wing edge; vein 3A absent, reduced to a stump, or extending along posterior margin of wing (N = 4).

Abdomen. Tergum 8 on central area with deeply pitted sculpticells forming transverse lines of various lengths, and lateral margin in central 0.3 shiny (as in Fig. B2.141, insert). Tergum 9 with meshes of microsculpture on ventral half below longitudinal furrow near center clearly impressed and sculpticells slightly raised as scales, meshes above longitudinal furrow near center well impressed and sculpticells clearly scale-like (as in Fig. B2.92, insert); median basin with base (outlined by two lateral black longitudinal furrows; N = 4) 0.8–1.0 times as wide as its median length, with maximum width of basin 1.6–1.7 times as wide as its median length and basin 0.40–0.46 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) about 0.8 times as wide as maximum width subapically (as in Fig. C1.15); with large teeth in apical 0.3 (Fig. B2.110). Sheath. Basal section 0.28–0.29 times as long as apical section (N = 4) (Fig. C17.1); lateral surface of apical section with well-defined ridge (as in Fig. B2.13, insert); length 1.3–1.4 times as long as fore wing length. Ovipositor. Lancet with 29–30 annuli (first 15 annuli hard to see, but still outlined (N = 4); junction of basal and apical sections of sheath aligned between 3rd and 4th annuli; major pits present on last 7 or 8 apical annuli before teeth annuli, and with a very small pit on each of the annuli 2–5 or 2–10), and a small pit on each of the annuli 10–13 (as in Fig. C1.18).


Color. Head generally with dorsal spot behind eye light reddish brown, clearly outlined, larger in size than spot of females, and extending to both sides of genal ridge (basically coma-like) (Fig. C17.2); clypeus, face, gena near mandible and postocellar furrow light reddish brown (except for dorsal spot, other pale spots may not be consistent based on other species of Xeris studied) (Figs. C17.2, C17.4 and C17.5). Pronotum with lateral band clearly outlined, about 0.3 times as wide as pronotal 0.5, the band remaining wide to posterolateral angle, and generally not extending to lateral edge of pronotum (Fig. B2.132). Coxae, trochanters and femora (except yellowish-white apex) black; protibia in basal 0.5 (Figs. B2.112 and B2.132), mesotibia in basal 0.4 (Figs. B2.132 and C17.2), and metatibia in basal 0.1 (Figs. B2.132 and C17.2) sharply light reddish brown, otherwise tibiae black. Pro- and mesotarsomeres 1, 2 and basal 0.5 of 3 light reddish brown, metatarsomere 1 mainly black (extreme base and apical 0.15 light reddish brown), metatarsomeres 2 brown; most of tarsomeres 3–5 of all legs dark brown or black (as in Fig. C17.2).

Thorax. Metatibia with shallow notch on dorsal edge in basal 0.25 (Fig. C17.2).

Taxonomic notes

AXeris xylocola is part of the X. spectrum lineage as shown by the presence of a pit on each of the most basal annuli. Adults of X. xylocola and X. xanthoceros are closely related based on the narrow shiny surface medially on the pronotum. This character state probably applies to both sexes. However, both sexes probably differ in the pit distribution on the lateral surface of the pronotum and in females in the color pattern of the flagellum.

Origin of specific epithet

The specific name “xylocola” means “living in wood” and is characteristic of larvae of Siricidae.


LAOS: Huaphan.

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