Dasydorylas gradus Kehlmaier, 2005

Kehlmaier, Christian, 2005, Taxonomic studies on Palaearctic and Oriental Eudorylini (Diptera: Pipunculidae), with the description of three new species, Zootaxa 1030 (1), pp. 1-48 : 36-39

Dasydorylas gradus Kehlmaier spec. nov. ( Figs 12a–j )

Type material

Israel 1♂ (holotype), Herzliyya , 27.VI.1982, leg. A. Freidberg, coll. TAU ; 1♀ (allotype), Herzliyya , 14.VII.1982, leg. A. Freidberg, coll. TAU ; 1♀ (paratype), Herzliyya , 10.VII.1982, leg. A. Freidberg, coll. TAU ; 1♀ (paratype), Herzliyya , 18.VII.1982, leg. A. Freidberg, coll. TAU .

Etymology

From the Latin “gradus” (a step); the name refers to the distinct step present on sternite 8 of the female ovipositor, visible in lateral view.

Description

Male

Body length. About 4.1mm.

Head. Face dark, silver­grey pollinose. Scape dark, with one or two upper bristles. Pedicel dark, with three upper and one short and one very long dark lower bristle. Flagellum dark, long tapering and grey pollinose (LF:WF=3.3). Arista dark with thickened and flattened base. Eyes meeting for 15 times diameter of ocellus. F:EM:V=1:0.9:0.4. Frons dark, silver­grey pollinose, with a median keel, including a small tubercle lacking pollinosity. Vertex dark, lacking pollinosity, bearing an equilateral and slightly elevated ocellar triangle. Occiput dark, grey pollinose, changing into brown in upper third.

Thorax. Prescutum, scutum scutellum and pleura dark. Pleura grey pollinose. Postpronotal lobe pale, grey pollinose and with five to seven postpronotal hairs along upper margin (up to 0.07mm). Prescutum and scutum grey pollinose in anterior third, along lateral margin down to wing base and partly narrowly along posterior margin, otherwise brown pollinose, with two uniseriate dorsocentral rows of hair and some supraalar hairs. Scutellum with posterior margin weakly grey pollinose, otherwise brown pollinose and with a fringe of six long (up to 0.13 mm) and six shorter (up to 0.07mm) black hairs, alternately arranged.

Wing. Length: 3.8mm. LW:MWW=3.2. Microtrichia of wing surface absent or largely reduced in small basal cells of wing, e.g. bc, almost the entire cell br, basal half of bm, basal third of c and cup, basal quarter of anal lobe, the beginning of r 1, r 2+3, r 4+5 and in the middle of sc. Pterostigma dark and complete (LS:LTC=1.0). LTC:LFC=1.4. r­m reaches dm between basal quarter and third of the cells length. M 1 straight.

Halter . Length: 0.4mm. Base and knob dark, stem pale.

Legs. Coxae dark, grey pollinose. Front and mid coxae with paler anteroapical margin. Mid coxa with five to six strong dark bristles on inner apical corner. Trochanters dark, partly grey pollinose. Front trochanter with one, mid trochanter with one or two strong dark bristles at anteroapical margin. Femora dark with pale apices, grey pollinose except hind femora shining posteroventrally. Mid femur with two ventral rows of dark peg­like spines, the anterior one restricted to apical half. Front femur with two, hind femur with an anteroventral row of spines in apical half. Tibiae with basal half and apical fifth to quarter pale, otherwise darkened, grey pollinose. Front and mid tibiae with short distal spines and one dark midposterior bristle. Hind tibia with a wrinkled indentation midanteriorly, bearing one strong, dark bristle. Tarsi pale, grey pollinose, with at least distitarsi darkened. Pulvilli as long as or slightly shorter than distitarsi.

Abdomen [removed posterior to tergite 1]. Ground colour dark. Tergite 1 with up to seven dark lateral bristles, becoming shorter towards the centre of the tergite, grey pollinose. Viewed dorsally, tergite 5 almost symmetrical (T5R:T5L=1.1). LT35:WS8=1.2. Viewed laterally, syntergosternite 8 slightly higher than long (LS8:HS8=0.9). Viewed caudally, membranous area in the shape of an inverted drop, occupying almost the entire right half and caudally directed ( Fig. 12c ).

Genitalia.

Genital capsule dorsal view: Epandrium small, wider than long (MLE:MWE=0.8). Surstyli symmetrical, both with a rectangular base and an inner apical projection that is turned outward at its end ( Fig. 12i ).

Genital capsule ventral view: Gonopods small ( Fig. 12a ). Phallus trifid, narrow, with long ejaculatory ducts that are somewhat bent ( Fig. 12a ). Phallic guide narrow, long and straight, in apical half laterally with 13 to 14 long, straight spines on either side, most of them pointing upwards into various directions ( Fig. 12a ). These spines can be partly missing.

Genital capsule lateral view: Epandrium without projecting lobe on either side. Surstyli apically bent towards sternites ( Fig. 12h, j ). Phallic guide bow­like bent towards dorsal surface of genital capsule ( Fig. 12b ). The lateral spines pointing into different directions.

Ejaculatory apodeme funnel­shaped ( Fig. 12d ).

Female

Differing from the male in the following points:

Body length. 3.6–3.8mm.

Head. Flagellum slightly paler than pedicel in apical half and long tapering (LF:WF=3.7) ( Fig. 12e ). Front facets greatly enlarged (0.06mm). Frons strongly widened in middle (MWF:WFA=1.9), with a short longitudinal median groove in upper quarter, its elevated rims fusing to form a median keel in middle two quarters, ending in a small tubercle, all shining. Basal quarter of frons entirely, middle two quarters laterally silvergrey pollinose. Lateral rows of setae almost reaching down to tubercle. Occiput brown pollinose only posterior to ocellar triangle.

Thorax. Postpronotal lobe with four to five postpronotal hairs along upper margin.

Wings. Length: 3.3–3.6mm. LW:MWW=3.3. Microtrichia reduced to a greater extend, especially in bm (almost entirely), c and cup (basal half) and in anal lobe (basal third). LS:LTC=1.0. LTC:LFC=1.2–1.3.

Legs. Mid coxa with three to five strong bristles on inner apical corner. Front trochanter without, mid trochanter with one bristle. Pulvilli distinctly longer than distitarsi.

Abdomen. Tergite 1 with four lateral bristles. Tergite 2 to 6 laterally grey pollinose, broadly extending onto dorsal surface in posterior half but not touching (almost on tergite 6), otherwise brown pollinose. Viewed dorsally, tergite 5 slightly longer than tergite 4. LT35:WT5=0.9. WT5:LT5=3.2. Sternite 1 to 5 greyish pollinose.

Ovipositor. Base and proximal part of piercer dark, weakly grey pollinose, subshining, except sternite 8 which is shining. Distal part of piercer pale and shining. Viewed dorsally ( Fig. 12g ), base rectangular to trapezoid, longer than wide, without a longitudinal median furrow. Suture between tergite 7 and 8 visible as a shining band. Anal opening ovate. Proximal part of piercer broad. Distal part broad at the very beginning than rapidly attenuating and needle like, reaching anterior half of sternite 2. Viewed laterally ( Fig. 12f ), proximal part of piercer (sternite 8) with a conspicuous step. Distal part of piercer thin and straight. LP:LB=2.2–2.4. LDP:LPP=2.3–2.5.

Discussion

The type material was originally published as Dasydorylas setosus (Becker, 1908) by De Meyer (1995). An additional female from the same locality (11.VII.1982, coll. TAU) mentioned in De Meyer (1995) was not studied but should also belong to this new species. At a later stage, De Meyer (1997) stated that the Israeli specimens differ from true Das. setosus and seem to belong to a hitherto undescribed species.

Das. gradus can be distinguished from Das. setosus , recently redescribed by Kehlmaier (2005), by its differently shaped male surstyli ( Figs 12h–j ) and striking phallic guide with its many slim and long spines ( Figs 12a–b ) as well as by the lateral shape of the female ovipositor ( Fig. 12f ). There might be a relation to the Eastern Palaearctic E. optabilis Kuznetzov, 1990 and E. hasanicus Kuznetzov, 1990 (both described from females only) in regard to the lateral shape of the ovipositor as figured in Kuznetzov (1990a: Figs 98, 99). However, the absence of lateral bristles on tergite 1 as well as the absence of distinctly stronger bristles on the posterior scutellar margin mentioned in the brief original description seems to separate them. Nevertheless, a re­examination of Kuznetzov’s types would be desirable.

Figures

FIGURE 12. Dasydorylas gradus Kehlmaier spec. nov. (a) Phallic guide, gonopods, hypandrium and phallus ventral view. (b) Phallic guide lateral view. (c) Syntergosternite 8 caudal view. (d) Ejaculatory apodeme. (e) Female antenna lateral view. (f) Ovipositor lateral view. (g) Ovipositor dorsal view. (h) Outer surstylus lateral view. (i) Surstyli strictly dorsal view. (j) Inner surstylus lateral view. Scale bars = 0.1 mm.