Brachymeria minuta

Delvare, Gérard & Huchet, Jean-Bernard, 2017, Brachymeria mochica, a new Neotropical species of Chalcididae (Hymenoptera: Chalcidoidea) discovered on the archaeological site of Huacas de Moche, Peru with a review of related species, Zootaxa 4290 (1), pp. 43-60 : 45-46

The Brachymeria minuta species group

Diagnosis. Head conspicuously transverse in frontal view ( Fig. 5 ). Both mandibles 2-toothed, the teeth blunt at apex, with lower tooth longer than upper tooth ( Fig. 8 ). Postorbital carinae present and complete, reaching posteriorly genal carina ( Fig. 7 ). Lower surface of gena trapezoidal, delimited, respectively, by postorbital carina, genal carina, and lateral margin of oral fossa. Pedicel squat, at most as long as broad in dorsal view and basally ‘bottle necked’ ( Fig. 11 ). Flagellum weakly fusiform, flagellomeres short and often strongly transverse and frequently bearing long, sparse and erect setae ( Fig. 10 ). Ventral section of the epicnemial carina never raised into submedian lobes. Apical truncation of metatibia clearly emarginate ( Fig. 15 ). Spatulate seta ( Steffan 1954) of posterior pretarsus slender and not curved very much, generally surpassing apex of pretarsus ( Fig. 16 ).

Subdivision. The minuta group can be subdivided into two distinct sections. The first one, here defined as the minuta section, includes primary parasitoids of synanthropic flies (mainly Sarcophagidae and Calliphoridae ) developing within carrion and dung, while the parvula section, comprises secondary parasitoids, mainly of Lepidoptera through Tachinidae ( Blanchard 1935; Burks 1960; Sychevskaya 1966; Louranção & Sabino 1994; Tavares et al. 2006), more rarely of Coleoptera or Orthoptera through Sarcophagidae or Anthomyiidae ( Steffan 1959; Burks 1960; Léonide & Léonide 1969).

The proposed subdivision is otherwise corroborated by several morphological features. The minuta section is characterized by: 1) outer surface of metafemur with moderately to distinctly sparse piliferous points only, with engraved network extremely superficial, visible at high magnification only [over 300×] ( Figs 24, 28 ); 2) metafemur with an inner basal tooth or tubercle; 3) posterior tarsus slender; 4) antennal scrobes never carinate dorsally ( Fig. 5 ). Additionally in most species, the mesonotum is completely punctured ( Figs 12 , 22, 26 ), at most areolate on anterior third in some species of this section. Conversely, species of the parvula section do not show the combination of characters stated above for the minuta section: outer surface of metafemur generally with an evident engraved, alutaceous network in addition to piliferous points and mesonotum areolate. Other characters of the parvula section are variable: the metafemur usually has no inner basal tooth and in some species the antennal scrobes are completely carinate and/or the posterior tarsus markedly broadened towards the apex.

The minuta section is represented in the New World by B. podagrica (Fabricius) , a species also widespread throughout the world. Otherwise, only species of the parvula section have been described from the Americas: B. aeca Burks, B. carinatifrons Gahan, B. compacta (Walker), B. compsilurae (Crawford), B. koehleri Blanchard, B. nigritibialis Tavares & Navarro-Tavares, B. parvula (Walker)—this latter species with a Holarctic distribution— B. tegularis (Cresson), B. truncatella (Burks) and B. weemsi Burks.

Species recognition. The Brachymeria minuta species group exhibits numerous variable characters that can be used for separating species: setation generally silvery but sometimes golden; sculpture of the labrum and clypeus; variable development of the preorbital carinae; density of the puncturation of the mesonotum; habitus of the posterior margin of the scutellum, resulting from the more or less deep emargination of the frenal carina; punctulation of the metafemur; habitus of the gaster which may be squat or acuminate, etc.

Diversity. The group includes at least 28 species already described from the Old World and 8 from the Americas, but the examination of diverse collections showed that many species remain undescribed.

Hosts and biology. The species for which the hosts and development are known are solitary endoparasitoids of Diptera , showing a koinobiont strategy, with the female ovipositing within the larval stages of the host while the adult emerges from the pupae (Stefani 1889; Roberts 1933; Dowden 1935; Léonide & Léonide 1969).

The biology of B. compsilurae (Crawford) was studied by Dowden (1935) in North America. The species develops within tachinids that are primary parasitoids of several species of Lepidoptera. In the Holarctic Region B. moerens (Ruschka) and B. parvula (Walker) parasitize sarcophagids and anthomyiides that are primary parasitoids of Orthoptera ( Léonide & Léonide 1969). The Brachymeria that develop at the expense of coprophagous or necrophagous Calliphoridae and Sarcophagidae are apparently attracted by chemicals given off by the organic tissues in which the flies feed and consequently can be trapped using meat or dead bodies ( Roberts 1933; Horenstein & Salvo 2012; Michel Martinez pers. com.; present paper).

Figures

FIGURES 5 – 13. Brachymeria mochica, holotype ♀. 5 – 7, head in frontal, dorSal and lateral VieWS, reSpectiVely. 8, right mandible. 9, clypeUS and moUth partS. 10, antenna exclUding Scape. 11, pedicel and baSe of flagellUm. 12, meSoSoma in dorSal VieW. 13, meSoScUtellUm in lateral VieW.

FIGURES 14 – 20. Brachymeria mochica, holotype ♀. 14, meSo- and metapleUron. 15, hind tarSUS. 16, hind pretarSUS. 17, baSe of fore Wing. 18, Stigmal and poStmarginal Vein. 19, metaSoma in dorSal VieW. 20, apex of metaSoma.

FIGURES 21 – 28. 21 ‒ 24, Brachymeria podagric a, ♀. 21, antenna exclUding Scape. 22, meSoSoma in dorSal VieW. 23, metaSoma in dorSal VieW. 24, metafemUr. 25 ‒ 28, Brachymeria amenocles, ♀. 25, antenna exclUding Scape. 26, meSoSoma in dorSal VieW. 27, metaSoma in dorSal VieW. 28, metafemUr.