Xenomerus Walker, 1836

Mikó, I., Masner, L. & Deans, A. R., 2010, World revision of Xenomerus Walker (Hymenoptera: Platygastroidea, Platygastridae) 2708, Zootaxa 2708, pp. 1-73 : 7-8

Xenomerus Walker

Xenomerus Walker, 1836: 342 , 355; type species: Xenomerus ergenna Walker, 1836 , by monotypy.

Trimorus: Kononova & Kozlov 2001: 231 , 233, 235, 238; Kononova & Petrov 1999: 21.

For subsequent taxonomic literature see Johnson (1992).

Diagnosis. Most similar to Trimorus Förster , differing in male flagellomeres A3–A11 bottle-shaped, with long, erect, whorl of bristles; mandible with three teeth of equal lenght; palpal formula 3:1with equal maxillary palp, scaly reticulate internotaular area, foveolate epicoxal sulcus. Basal depressions on the third metasomal sternum is are present only in Xenomerus within Teleasinae, however the depressions are absent in X. noyesi and X. vanharteni .

Description. FEMALE: Body length: 0.58–1.66 mm.

Body black to yellow, apical tarsomeres darker than proximal tarsomeres, interantennal process usually lighter than head.

Head transverse, almost as high as wide; 1.5–2 times as long as high; usually about 1.5 times as wide as inter orbital space, in X. spinosus HW /IOS=1.85; interorbital space usually shortest at or above eye midlevel, in X. spinosus interorbital space shortest below eye midlevel; head 1.2–1.5 times as wide as transscutal line; mandible short, broad, with three teeth ( Fig. 20); teeth size invariant; facial striae short, not reaching (e.g. Figs 28, 29, 44, 45, 86, 87), or long, extending over (e.g. Fig. 80) but not obscuring or sometimes obscuring frontal patch (e.g. Figs 38, 39, 63, 68, 74), in some cases reaching anterior ocellus (e.g. Figs 56, 57); frontal patch distinct (e.g. Figs 28, 29, 44, 45, 80), sometimes extending dorsally of eye midlevel ( Fig. 87), or indistinct, obscured by facial striae; median area on frons smooth and bare, usually at least 0.5 times as wide as IOS ( Fig 56), in X. rugifrons reduced in size, and almost entirely obscured by facial striae ( Fig. 57); central keel usually present, incomplete (e.g. Figs 44, 45, 65), or complete ( Figs 28, 29, 37–39, 56, 63, 67–69, 74), absent in X. noyesi , X. fulleri and X. rugifrons ( Fig. 57); toruli triangle well developed, usually closed dorsally, in X. fulleri and X. rugifrons opened dorsally ( Fig. 57), usually shorter ( Figs 28, 29, 38–39, 56, 63, 65, 68, 69, 74, 75), in X. rugifrons longer ( Fig. 57) than clypeus length; POL 0.86–3.00 times as long as OOL; vertex patch absent (e.g. Figs 24, 73) or present (Figs, 25, 37, 108), sometimes continuous with vertex sculpture ( Figs 26, 27, 54, 55, 64, 66, 84, 88); hyperoccipital carina sharp, extending to orbit ( Fig. 24) or extending between lateral ocelli ( Figs 25, 36, 66), or blunt, extending to orbit ( Figs 36, 67), or absent ( Figs 26, 27, 31, 54, 55, 89); genal patch present, segregated from vertex sculpture ( Figs 25, 81) or continuous with it ( Figs 26, 27, 31) or absent ( Fig. 71); hypostomal pit located usually closer to posterior tentorial pit than to oral foramen, in X. vanharteni hypostomal pit located closer to the oral foramen; palpal formula 3:1 with palpal segments equal in length ( Fig. 93).

Antenna: radicle elongate (A1/r=2–3) (Figs 13, 14) or short (A1/r=5–6) (Figs 12, 15); claval formula usually 2:2:2:2:1, 1:2:2:2: 1 in ergenna -group; A3 usually shorter than pedicel (Figs 12, 14, 15), in X. spinosus and X. rugifrons A3 as long as A2 (Fig. 13); scape about as long as clava.

Propleural epicoxal sulcus foveolate (e.g. Figs 22, 51, 58, 59, 76, 98); propleural cervical sulcus foveolate (e.g. Figs 76, 77) or simple ( Figs 51, 98); propleuron scaly reticulate ( Figs 51, 58, 59, 76, 98); anterior process of pronotum usually well developed ( Figs 76, 77, 98) in ochraceus -group reduced ( Fig. 51); pronotal cervical sulcus is foveolate ( Figs 76, 77) or simple ( Figs 58, 59); pronotal suprahumeral sulcus simple ( Figs 58, 98) or foveolate, complete, merged with pronotal cervical sulcus ( Figs 76, 77), or incomplete ( Fig. 51); epomial carina well developed ( Fig. 60) or absent ( Figs 22, 51, 58); posterior pronotal sulcus with row of setae present; netrion sulcus present, complete (e.g. Figs 22, 58, 59), incomplete ( Fig. 76) or absent (51, 60, 77); sometimes netrion sculpture strongly extending anteriorly onto lateral pronotal area ( Figs 59, 93 97); netrion usually spindle-like; mesonotal suprahumeral sulcus foveolate, not extending to antero-admedian line (e.g. Figs 25– 27, 36, 81); mesonotal humeral sulcus usually foveolate ( Figs 76, 77), in X. vanharteni both sulci simple, without foveae ( Fig. 24); notaulus elongate, almost reaching anterior margin of mesoscutum (e.g. Figs 25, 30, 31), normal, almost reaching transscutal line (e.g. Figs 54, 55, 61), short, not reaching transscutal line ( Figs 64) or absent in X. vanharteni ( Fig. 24) and in ochraceus group ( Fig. 42); mesoscutum with posteriorly diminishing scaly reticulate sculpture, usually not reaching posterior margin, with sparse ( Figs 30, 31, 64, 65) or dense ( Figs 42, 54, 55, 61) setae, sometimes setal bases pustulate resulting in coriaceous-like sculpture ( Figs 54, 78); mesoscutellum transverse, 1.7–2.5 times as wide as long; usually simple, in X. spinosus and X. armatus with median spine ( Fig. 34); mesoscutellum with sparse marginal setae ( Figs 24–27, 73), in some species with dense setae ( Figs 54, 61); scutoscutellar sulcus foveolate, slightly ( Figs 73, 78) or distinctly ( Figs 79, 81, 88) diminishing medially, extending onto axillula; transaxillar carina present, merged with axillular carina; posterior scutellar sulcus foveolate, reaching axillula laterally ( Fig. 34); subalar pit well developed; acropleural sulcus well developed, sometimes almost reaching anterodorsal edge of mesopleuron ( Fig 76, 77); prespecular sulcus and mesepimeral sulcus not merging on speculum; pleural pit well developed; mesopleural epicoxal sulcus foveolate; sternaulus usually not separated from row of foveae extending anteriorly of mesopleural carina ( Figs 76, 77), sometimes well separated ( Fig. 93); postacetabular sulcus foveolate, postacetabular patch present; mesopleural carina usually complete with two rows of foveae extending along its entire length ( Figs 76, 77), sometimes incomplete ( Figs 22, 93) in X. vanharteni almost entirely reduced ( Fig. 23); mesepimeral sulcus foveolate, extending to mesocoxa; metanotal trough foveolate; metascutellum striated proximally; metanotal spine bluntly triangular, basal striation of metascutellum extending to metanotal spine ( Figs 42, 54, 102, 103), or with apical semitransparent lamella ( Figs 26, 27, 31) or pointed; reduced ( Figs 76, 78) or well developed ( Figs 77, 79); metapleural pit and metapleural sulcus present, upper and lower part foveolate; paracoxal sulcus foveolate ( Figs 76, 77) or simple ( ergenna group; Figs 22, 23) ventrally fo the metapleural carina; plica usually absent, in X. vanharteni present; lateral propodeal carina well developed, inverted V or Y-shaped ( Fig. 50), slightly curved outward or inward or S-shaped ( Fig. 43); metasomal depression and lateral propodeal area striated at least along margins (e.g. Figs 43, 50), marginal striation sometimes extending medially, entirely obscuring lateral propodeal area; posterior propodeal projection absent (e.g. Figs 43, 50), tubercle-like or well developed (e.g. Figs 72).Fore wing wider or slightly narrower than mesoscutum; marginal vein 2–3 times as long as stigmal vein; marginal ciliae of hind wing elongated, hind wing less than 2 times as wide as marginal ciliae length.

Metasoma transverse, usually circular in shape, T3 as wide or slightly wider than mesoscutum; T1 with 2 lateral setae; basal depressions on T1 and T2 present, T1 usually concave in lateral view, in X. malawi slightly convex; lateral patch on T2 distinct (e.g. Figs 32, 33) or indicated only by a few setae (e.g. Figs 36, 48, 49); basal depressions on T3 usually present (e.g. Figs 32, 33, 48, 49, 52, 53), in X. noyesi and X. vanharteni absent ( Figs 92), if basal depressions on T3 present, then basal depressions on S3 present ( Figs 110–117); costae arising from basal depressions, sometimes almost reaching posterior margin (Figs, 90, 91), sometimes T3 longitudinally rugulous ( Figs 35, 62); lateral patch on T3 present (e.g. Fig. 35) or absent; posterodorsal patch on T3 present, sometimes obscured by basal sculpture of tergum (e.g. Fig 52); apical setae on T3 as long as setae located laterally on tergum ( Figs 90, 91) or more than two times as long as lateral setae ( Figs 48, 49); basal depressions on S1 and S2 present ( Figs 111, 112–117).; lateral and medial patches on T4 usually present, not fused (e.g. Figs 53, 90, 91), medial patch on T4 sometimes absent or marked by punctures (e.g. Fig. 92), sometimes anterior T4 entirely reticulate, lateral and medial patches fused (e.g. Fig. 35); felt field present; posterior felt field absent; acrosternal calyces fused medially and circular in shape ( comatus - and ergenna - groups Figs 112, 114–117), separated medially and circular in shape but ( ochraceus -group Fig. 113) or well separated and transversely elongate ( melleus -group Figs 21, 110, 111); number of apical setae on T7+8=2 ( ergenna -group) or =4; median extensions of lateral apodemes of T7+8 separated, slightly converging ( Figs 115, 117) proximal part of ventral membranous plate simple, without rod-like structure anteriorly, median apodeme on S6 present.

MALE: Differs from female in wider and shorter head, sometimes almost 1.5 times as wide as high ( X. melleus , Fig. 94); inter orbital space shortest below eye midlevel; A6–A11 ( Figs 18, 19) or A7–A11 (Figs 9, 10, 16) with stronger ( Fig. 16) or weaker ( Fig. 19) median constriction (dibottled) with two whorls of setae, or without constriction (unibottled) with one whorl of setae ( Fig. 17); A3–A11 with 1–3 (few) (Figs 12, 16–19) or with 6–10 (numerous) (Figs 9, 11) ventral microciliae; A5 distinctly modified ( Figs 18, 19) or not modified (Figs 9, 10, 11); posterior felt field present.