Pachygaster hymenaea, Grund, Martin & Hauser, Martin, 2005

Grund, Martin & Hauser, Martin, 2005, Pachygaster hymenaea sp. nov. and P. antiqua James, 1971 (Diptera: Stratiomyidae) in Neotropical ambers, Zootaxa 1061, pp. 29-34 : 30-33

Pachygaster hymenaea , sp. nov.

Etymology

Named after the tree genus Hymenaea , which is the source of the fossil resin. The tree genus was named for Hymen, the god of marriage in Greek mythology.

Material

P. hymenaea , sp. nov.: Female (holotype); in the collection of Staatliches Museum für Naturkunde Stuttgart ( SMNS), Germany, label: Do­3495­M.

The size of the amber piece is about 5x4x 3 mm, of irregular shape, but the plane and polished surfaces allow good view of the fossil ( Fig. 1 ). The fossil is complete and very well preserved, with wings and legs spread. The matrix is highly transparent, with few internal cracks and only some air bubbles. The colour is clear yellow.

P. antiqua : Female (holotype); in the collection of University of California Museum of Paleontology ( UCMP), Berkeley, California, label: locno B­7041­19 specno 13501. The size of the amber piece is about 8x5x 4 mm. The amber matrix is quite dark and intense light is needed for examination of the inclusion. The dorsal parts of thorax and abdomen, the right eye and most of the wings are lacking.

Diagnosis

Pachygaster hymenaea sp. nov. is a very typical pachygastrine and very similar to the previously described Pachygaster antiqua James. The new species can be separated by its clearly elevated ocellar area ( Fig. 3 a) in which the ocelli are situated less than one ocellus diameter apart. In contrast P. antiqua has a nearly flat ocellar area, and the ocelli are separated from each other at least one ocellus diameter ( Fig. 3 b). The width of the frons across the frontal ocellus is about 0.25 mm, which is much broader than in P. antiqua (0.17 mm).

Description

The statements about the color of certain body parts must be viewed with caution because the true coloration of the insect was altered by the fossilization process and is also dependant on the light and angle of view.

Head: Antenna short oval, light brown; arista inserted slightly above middle of flagellar complex; arista three times as long as flagellar complex, with a few scattered setae ( Fig. 2 a). Ocellar triangle compact and raised distinctly. Distance between ocelli less than one ocellus diameter ( Fig. 3 a). Eyes broadly separated; frons spanning one­third of head diameter, sparsely covered with short setae, latter more abundant on dorsolateral part of frons. Frontal width across frontal ocellus about 0.25 mm. Head extended little beyond eyes, dorsal occipital area posterior to eyes narrow, approximately twice the width of an ocellus. Postocular area small, greatest width four ocellar diameters wide. In lateral view no cheeks visible ventral of eye margin. Labella of proboscis spanning three­quarters of length of head, palpus very small and black.

Thorax: Black with deep transverse suture, covered with short setae. Scutellum semicircular, convex, apical margin depressed in lateral view, with row of minute tubercles, each bearing a short seta ( Fig. 2 b). Legs brownish, mid and hind tibiae as well as tarsi light yellow. Perhaps femora and fore tibia black in living specimen. Wings covered mostly with microtrichia, absent on basal three­quarters of cell cu­p, most of intervenal area, and small basal part of anal cell ( Fig. 2 c). Halteres transparent yellowish white. Abdomen of typical rounded shape of many Pachygastrinae .

Body length 2.3 mm; wing length 2.2 mm.

Figures

FIGURE 1: P. hymenaea sp. nov., habitus photo.

FIGURE 2: P. h y m e n a e a sp. nov., a: antenna (ventral view) scale bar 0, 1 mm; b: scutellum (dorsal view) scale bar 0, 2 mm; c: wing, scale bar 1 mm.

FIGURE 3: Ocellar area of a: P. hymenaea sp. nov. (angular frontal view) scale bar 0, 2 mm; b: P. antiqua (dorsal view) scale bar 0, 1 mm.