The Wharton Lab

Opius (Merotrachys) melchioricus Fischer, 1979: 264–266 (key); 271–273 (description). Holotype male in AEIC (examined).
Opius (Merotrachys) melchioricus: Yu et al. 2005, 2012 (electronic catalogs).

Known for over 30 years only from the male holotype. Female characters are based on a specimen collected at the type locality in Brazil (TAMU). The female differs from the holotype primarily in wing venation, with 3RSa about 1.5 x longer than 2RS and the wing is more nearly hyaline. Otherwise, body coloration and sculpture are the same.

Face (Fig. 3) finely but distinctly punctate, punctures separated by nearly 2 x their diameter, strongly shagreened adjacent eye margin, otherwise smooth between punctures. Eye in lateral view (Fig. 4) roughly 2.5 (male) and 3.0 (female) x longer than temple; temples in dorsal view not or only weakly receding (Fig. 5). Female antenna with 53 flagellomeres, male holotype (Fig. 1) with 56–57 flagellomeres; setae on basal flagellomeres thin, pale. Mesoscutum anteriorly on nearly same plane as pronotum (Fig. 7), without distinct anterior declivity; notaulus (Fig. 5) extending laterally towards tegula as groove bordered by distinct supramarginal carina. Propodeum coarsely carinately rugose with deep median trough anteriorly separated by carina from broad median, roughly pentagonal to elliptical areola posteriorly, areola relatively well-defined, carinately sculptured medially. Fore wing (Fig. 10) with 3RSa straight, 1.3 x longer than 2RS; m-cu postfurcal. T1 sharply declivitous anteriorly (Fig. 8), pit delimited posterior-medially; surface carinately rugose medially, rugulose laterally; dorsal carinae (Fig. 9) distinctly elevated, nearly parallel-sided throughout, weakly converging posteriorly, not sinuate, transversely carinate between dorsal carinae. T2 and T3 distinctly shagreened. Ovipositor short; ovipositor sheath about 0.3–0.4 x length of mesosoma. Color as in Figs 1, 2: with head, body, hind coxa and femur orange to pale orange; tegula, posterior margins of mesonotum, metanotum, and T3–6 dark reddish brown, T6 more uniformly weakly infumate; antenna without pale subapical ring; wing infumate in male, more nearly hyaline in female.

This species is characterized by the dark transverse markings on the posterior margins of the meso- and metathorax (Fig. 6). It is most similar to O. rojam , O. gabrieli and O. ingenticornis . All four species have very short ovipositors, heavily sculptured propodea, thinner, pale setae on the basal flagellomeres, and are predominantly orange. Opius antennatus, O. matthaei , O. petri , and O. raphaeli are darker but otherwise share these features and together these eight species form a larger subgroup within the ingenticornis species group. Opius gabrieli is most readily recognized by the black apical metasomal terga relative to O. ingenticornis , O. melchioricus, and O. rojam. O. ingenticornis and O. rojam are more uniformly orange and the face is more completely shagreened than in the other two species whereas O. melchioricus has the tegula black with dark transverse lines across the posterior margins of the meso- and metathorax.

Additionally, as in all other members of the ingenticornis species group, this species can be further characterized as follows: Mandible short, broadly triangular, dorsal margin strongly angled ventrally, broadly exposing labrum. Clypeus shaped as a broad crescent, nearly hemispherical, flat to weakly protruding ventrally, ventral margin shallowly concave, rarely appearing truncate. Malar sulcus distinct, complete. Antenna unusually long, approximately twice longer than body; first flagellomere slender, longer than second, with long, narrow plate sensilla. Occipital carina broadly absent dorsally, the gap in dorsal view at least as wide as distance between eyes; carina well developed laterally and ventrally, widely separated from hypostomal carina ventrally. Pronope deep, wide, posterior margin at least weakly overlapping base of mesoscutum, thus obliterating posterior transverse sulcus medially; vertical carina absent on pronotum laterally. Mesoscutum without midpit; notaulus short, curved, pit-like anteriorly, narrowing and evanescent posteriorly. Propodeum with median depression at least anteriorly, never with median longitudinal carina. Mesopleuron without sternaulus, precoxal sulcus unsculptured, absent or very faintly indicated; hind margin of mesopleuron not obviously crenulate on dorsal 0.5. Fore wing 2CUb arising from or near middle of first subdiscal cell. Hind wing with RS distinctly infumate; m-cu absent. T1 with dorsal carinae parallel or nearly so, extending from base to apex; laterope large, deep; dorsope absent.

Brazil, Guanabara, Reprêsa Rio Grande.

Labels attached to the holotype are in Fig. 1.

This page was assembled largely by Xanthe Shirley and Bob Wharton. It is part of a revision of the Opius ingenticornis species group conducted by Sophia Daniels, Xanthe Shirley, Danielle Restuccia and Bob Wharton, published by Wharton et al. (2013). We thank David Wahl (American Entomological Institute, Gainesville, FL) for loans and general assistance associated with examination of holotypes, as well as Max Fischer and Dominique Zimmermann (NHMW), Henri Goulet (CNC) and Paul Marsh (formerly USDA, Washington, D. C.) for facilitating other loans and work with material in their care. We are also sincerely grateful to Jim Woolley and Aaron Tarone for making available their imaging systems when ours crashed. Matt Yoder provided guidance on databasing issues associated with our use of mx. This work was conducted at Texas A&M University and was supported in part by NSF DEB 0949027, with REU supplement 1213790. Page last updated May, 2013.

This material is based upon work supported by the National Science Foundation under Grant Number DEB 0949027 and associated REU supplement 1213790.
Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.