Reevaluation of the odd chrysidid genus Atoposega Krombein (Hymenoptera, Chrysididae, Amiseginae)

Abstract The south Asian amisegine genus Atoposega Krombein, 1957, is reevaluated. Three new species, A. rufithorax, A. striata and A. thailandica are described from Thailand and the previously described species, A. lineata (Krombein, 1957) from Borneo, A. rieki (Krombein, 1957) from Myanmar and A. simulans Kimsey, 1986 from Malaysia are redescribed. The species, A. decorata Kimsey, 1995, was found to lack the generic characters diagnostic for Atoposega. Atoposega is only known from females.


Introduction
Female Atoposega Krombein, 1957 are among the more striking members of the chrysidid subfamily Amiseginae. They are brightly colored and elaborately sculptured, with long, spine-like propodeal teeth (a feature shared with female Mahinda Krombein, 1983) and often banded wings. However, Mahinda females are strongly brachypterous. Thus far Atoposega is only known from females. The only other genus with the same Rs vein configuration is Perissosega Krombein, 1983 from Sri Lanka, which is known from both sexes. Perissosega females are fully winged and have a well-developed transverse frontal carina. No male amisegines are known that have the distinctively angulate Rs vein seen in male and female Perissosega and in female Atoposega.
Species of Atoposega are known from southern Asia (Fig. 1). The intensive survey of Hymenoptera of Thailand, a U.S. National Science Foundation project, NSF No. 0542864, headed by Michael Sharkey revealed several additional species of Atoposega. The one species outside of this region, Atoposega decorata Kimsey, 1995, from New Caledonia lacks many of the generic traits that characterize Atoposega and is probably not congeneric. Thus this species is not included in this study, and will be treated in a separate paper.
Nothing is known of the biology of Atoposega species, although it is assumed that they are parasites of walking stick eggs like other members of the subfamily.

Materials and methods
Specimens were studied from the following institutions and/or these are the type repositories: AEI -American Entomological Institute, Gainesville, Florida, USA; BME -Bohart Museum of Entomology, University of California, Davis, USA; MCZ -Museum of Comparative Zoology, Harvard University, Cambridge, Massachusetts, USA; MNHN Terminology used below follows that of Kimsey and Bohart (1991). Proportions of the flagellomeres are based on the greatest length versus the broadest part of the article, generally the apical margin.

Diagnosis.
Female Atoposega most closely resemble those of Mahinda Krombein based on the acute or spine-like propodeal angles and mesopleuron with-well developed omaulus. Female Atoposega differ from Mahinda as they are fully winged (all known Mahinda are strongly brachypterous), the hindcoxa has with two longitudinal carina (one or none in Mahinda), and the mesopleuron has a dorsally carinate and U-shaped posteromedial groove (a narrow, parallel-sided longitudinal groove in Mahinda). In addition Mahinda females have two sharp submedial angles above the posterior propodeal declivity, which do not occur in Atoposega. Perissosega females are fully winged, but unlike Atoposega and Mahinda have a transverse frontal carina, and lack an omaulus. Atoposega can be distinguished from other amisegine genera by these characters, and by the dentate tarsal claws, malar space with a vertical sulcus, frons without transverse carina, vertex without longitudinal welt, pronotum with posteromedial longitudinal pit, and short sulcus and pit adjacent to lateral posterior lobe, mesopleuron without scrobal sulcus, metanotal dorsal enclosure usually V-shaped, propodeum with two dorsomedial decumbent angles and posterior declivity smooth and impunctate, with longitudinal medial carina, and forewing with an arcuate Rs vein.
Distribution. Atoposega species have been collected in Myanmar, Borneo, Thailand and Malaysia.
Material examined. Malaysian Borneo: Sandakan. Only the type series has been seen.
Diagnosis. This species most closely resembles simulans and less so thailandica. All lack the dense U-shaped scratches on metasomal tergum II. Atoposega lineata and thailandica both have banded wings, but lineata can be distinguished by the hindocellus separated from the eye margin by more than one diameter and flagellomere I less than 4× as long as broad.

Material examined. Type unavailable for study; Myanmar.
Diagnosis. Atoposega rieki most closely resembles rufithorax and striata based on the presence of fine dense longitudinal scratches on metasomal tergum II that join posteriorly, appearing broadly U-shaped. It can be distinguished from those species by the narrower subantennal distance, midocellus separated from the eye margin by less than two midocellar diameters, and banded wings.
Female description (based on Krombein 1957). Body: length 6 mm. Head: face scapal basin transversely ridged medially; frons with punctures deep, contiguous; malar space 3.5 midocellus diameters long; head 0.9× as long as wide; midocellus 1.3 midocellus diameters from ocular margin; ocelli arranged in isosceles triangle; hindocellus separated from ocular margin by 0.9 diameter; clypeus apicomedially indented; subantennal distance 0.7 midocellus diameters: flagellomere I length 3.7× breadth; flagellomere II as long as broad. Mesosoma: pronotal, scutal and scutellar punctures 0.3-0.5 puncture diameter apart; pronotum 0.6× as long as scutum, scutellum and metanotum combined; scutum with notauli well-developed anteriorly, broader posteriorly; mesopleuron with punctures contiguous to 0.5 puncture diameter apart; metanotum 0.9× as long as scutellum; hindfemur minutely, finely rugulose ventrally. Metasoma: tergum I smooth, impunctate in medial half, lateral fourth finely, longitudinally carinate; tergum II with basal triangular, finely punctate area, laterally with dense, longitudinal carinae joined posteriorly into U-shape; terga III and IV finely, densely punctate; sterna II and III with large, dense punctures. Color: head black; antenna dark brown, except scape, pedicel and flagellomere I paler basally and apex of flagellomere I blackish; flagellomeres II-XI blackish; thorax red, except dorsal and posterior face of propodeum black; legs brown, except coxae, trochanters, femora and ibiae narrowly basally red, hindtibial apex and venter of hindfemur dark brown; metasoma shiny black, with faint green tints on terga I-II; wing membrane with alternating pale or brown bands. Diagnosis. This is one of three species, including striata and rieki, with fine dense longitudinal carinae on the sides of metanotal tergum II that join posteromedially. It can be distinguished from those species by the lack of an elevated, medial metanotal ridge, and the scutellum roughly planar with the metanotum and separated from the metanotum by a deep notch in side view.
Etymology. The name refers to the red coloration of the thorax. in the months of December, January and April-October; 22 females were examined including the holotype (BME, AEI). Diagnosis. This species most closely resembles lineata based on dimensions of the flagellomere I, the lack of longitudinal striae on metasomal tergum II and the hindocellus separated from the nearest eye margin by more than one diameter. Atoposega simulans can be distinguished from lineata by the lack of lateral longitudinal scratches on metasomal tergum I and evenly brown-tinted wings.

Atoposega striata
Diagnosis. This species is closest to rufithorax based on dimensions of the flagellomeres, length of the subantennal distance and lack of a posterior propodeal enclosure. It can be distinguished from rufithorax by the presence of an elevated, medial metanotal ridge, the scutellum elevated above metanotum and separated from the metanotum by a deep notch in side view, and clypeal apex truncate not broadly rounded as in rufithorax.
Etymology. The species name refers to the fine longitudinal scratches on the dorsum of the mesosoma. Diagnosis. This species most closely resembles lineata and simulans based on the lack of fine dense U-shaped striae on metasomal tergum II. The banded wings resemble those of rieki and lineata. Atoposega thailandica can be distinguished from these species by the combination of flagellomere I 4× as long as broad (versus 3×) and hindocellus separated by less than 1 diameter from the nearest eye margin.
Etymology. The species is named after the country of collection.