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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

Genus Eriotremex Benson

Fig. C31.1 (live female)

Eriotremex Benson, 1943: 42. Type species: Tremex smithi Cameron, by original designation.

Diagnostic Combination

Among specimens with no fore wing vein 2r–m [species of Tremex and Afrotremex], both sexes of Eriotremex are recognized by the fore wing cell 2R1 about 0.5 times as long as cell 3R1, the dense and long pubescence covering the body, and the antenna with at least 12 flagellomeres. Female also have deep pits on the basin of tergum 9 and cercus thumb-like cercus.


Color. Variable generally body mostly or entirely black and wings black tinted, but wasps-like color patterns with less darkly tinted wings known in a few species.

Head. Antennal sockets with distance between their inner edges 4.0–5.0 times distance between inner edge of eye and outer edge of socket. Distance between inner edges of lateral ocelli 1.7–2.2 times as long as distance between outer edge of lateral ocellus and nearest edge of eye. Maximum distance between outer edges of eyes clearly less than maximum width of head (thus, in frontal view, genal edges completely visible and not intersected by outer edges of eyes). Minimum distance between inner edges of eyes about as long as maximum eye height. Gena without ridge behind eye and without white spot, with large pits, each elevated along posterior edge as low tooth. Head with setae sharp at apex. Flagellum with 16–19 flagellomeres, and middle flagellomeres in dorsal view 0.8–0.9 times as long as wide (Fig. B1.23); middle flagellomeres with sensory pits over ventral and most of dorsal surface (part of outer lateral surface without sensilla) and ventral surface separated from dorsal surface by a sharp fold especially on inner side.

Thorax. Pronotum smooth or pitted over less than 0.5 of anterior vertical surface. Mesoscutum entirely densely pitted. Metatibia with one apical spur, and in male, metatibia in lateral view about 5.0 times as long as maximum width, and in cross section rather compressed. In both sexes metatarsomere 1 in lateral view 0.8–0.9 times as long as maximum length of metatibia, in female, 0.7 times and in male 1.0 times as wide as maximum width of metatibia. In female, metatarsomere 2 in lateral view 2.0–3.0 times as long as maximum height. Metatarsomere 5 shorter than metatarsomeres 2 + 3. Fore wing with apex acutely and angularly rounded, without vein 2 r–m, with cell 3R1 3.0–3.8 times as wide as long, with cell 2R1 about 0.5 times as wide as cell 3R1, with vein 2r-rs joining stigma near middle, and with stigma gradually attenuated even distal to junction with vein 2r-rs (Fig. B1.25), without vein Cu1, with vein 1cu–a joining vein Cu close to or at vein M, with vein SC scarcely outlined in basal 0.15, with vein 2A extending along posterior edge of wing for 0.5 times length of cell 1A, and with vein 3A present and clearly extending along posterior margin of wing (Fig. B1.25). Hind wing without anal cell (as in Figs. B1.15 & B1.16); hamuli present apical to junction of veins R1 and C (as in Fig. B1.12).

Abdomen. Female. Cornus in dorsal view very short and lateral edges not angular, markedly convergent, but not constricted (Fig. B1.29). Tergum 1 laterally and medially and terga 2–6 laterally deeply pitted, each pit with long setae (Figs. C31.1 & C31.2). Tergum 9 with median basin deeply pitted, the pits scattered to dense, with surface markedly convex, about as long as wide, and lateral edges round and clearly outlined for 0.75 of median length of basin (Fig. B1.29). Sterna 2–7 pitted at side, more finely so toward middle. Cercus present, quite small, and thumb-like. Sheath. Basal and apical sheath sections clearly separated by a membrane; basal section more than 2.0 times as long as apical section (Fig. C1.40); apical section with teeth dorsomedially; median margin of basal section on ventral surface of sheath at very base without transverse ridges, but with setigerous pits in basal third each clearly raised as a forward directed tooth. Ovipositor. Lancet with 13 annuli, but annuli not outlined at base for a distance equal or greater than length of basal section of sheath; posterior portion of apical annuli with single pit and edge without tooth; last two annuli before teeth annuli without pit, preceding two annuli with a pit, each pit sharply outlined on most of ventral edge, anterior annuli following above two pits with similar sized pits, and each pit midway between dorsal and ventral edges of the lancet; edge of last 3–4 annuli before teeth annuli not sinuate, extending toward ventral margin but not reaching it, and edge of annulus not developed as tooth (Fig. C31.3).

Diversity and distribution

This genus with 12 species (we studied eight species) is moderately diverse in southeastern Asia (from Japan, southern China including Taiwan to eastern India and Papua New Guinea) (Taeger and Blank 2008, Taeger et al. 2010), but in North America the genus consists of a single introduced species, Eriotremex formosanus. The species is reported from southeastern United States. It is common and still spreading (Smith 1996). Benson (1943) gave a key to 7 species, Maa (1956) to 8 species based on females, and Smith (2010) to 12 species based on females. Males are known only for three species, E. formosanus (Matsumura), E. malayanus Benson and E. viridiceps Cameron.

Species List

One species treated: