Margdalops bifilum, Jindr & Rohác & ek & Barraclough, 2003

Jindr, Rohác, ich, ek & Barraclough, David, 2003, Margdalops, a new African genus of Anthomyzidae (Diptera), comprising six new species, African Invertebrates 44 (2), pp. 1-35 : 24-26

Margdalops bifilum sp. n.

( Figs 49–54 , 70 )

Type material: Holotype male, labelled: ‘ KENYA, Kakamega Forest , 20–21.XI.1986, A. Freidberg’ ( TAUI, genit. prep.) . Paratype: KENYA: same data as holotype, 1 male (somewhat damaged; TAUI, genit. prep.) .

Etymology: The name refers to distinctly ‘doubled’ filum (composed of two band-like sclerites) of the distiphallus.

Description: Male.

Total body length 2.18–2.23 mm. Body brown and yellow.

Head: Slightly longer than high. Frons dark brown, only foremost part paler brown. Orbit brown, without micropubescence and shiny. Frontal triangle distinct, reaching anterior fourth of frons; its surface and stripes between it and orbits sparsely grey microtomentose; ocellar triangle relatively flat and shiny. Face almost uniformly ochreous brown. Gena pale brown with darker ventral margin, greyish microtomentose like face; postgena dark brown. Mouthparts brownish dorsally, ochreous yellow (including palpus) ventrally. Chaetotaxy: pvt short, with apices crossed; vte longest of cephalic setae; vti shorter than vte; oc distinctly shorter than vti; posterior ors almost as long as vte. Eye with longest diameter about 1.3 times as long as shortest one. Gena very narrow also posteriorly; its minimum depth less than 0.05 times as long as shortest eye diameter. Antenna entirely brown to ochreous brown; 1st flagellomere lightest (ochreous) ventrobasally; arista twice as long as antenna, with sparse long cilia.

Thorax: Brown except for yellow ventral portion. Mesonotum brown to dark brown, sparsely greyish microtomentose. Pleural part of thorax with a broad brown dorsal band, covering also most of mesopleuron and pteropleuron; remainder of pleura (including ventral margins of mesopleuron and pteropleuron) yellow. Chaetotaxy as in M. venustus , but hu, both npl and, particularly, prs shorter, and, on the contrary, both stpl longer. Scutellum relatively flat dorsally. Legs yellow, with femora and tibiae ochreous. Pedal chaetotaxies as in M. venustus , but f 3 with only 9–10 setae in posteroventral row, 4–5 of which are thickened. Wing ( Fig. 70 ) similar to that of M. venustus , but more widened in distal fourth, R and M less convergent apically, discal (dm) cell longer with r-m situated slightly anterior to its middle and CuA 1 more bent. Wing measurements: length 2.22–2.27 mm; width 0.63–0.65 mm, Cs 3: Cs 4 = 3.00– 3.20, r-m/dm-cu: dm-cu = 5.71–6.67. Haltere blackish brown, with brown stem.

4+5

Abdomen: Dark brown including sterna, only T6 unsclerotised, pale pigmented, small and transverse. T3–T5 large and long. Preabdominal sterna broader than those of M. venustus , pleural membrane reduced. S5 shorter than S4 and distinctly emarginate posteromedially. S6 shorter than in M. venustus , and its ventral projection very thin.

extension). 50.Aedeagal complex, lateral view. 51. Hypandrium and associated structures, lateral view. 52. Transandrium, caudal view. 53. External genitalia, caudal view. 54. Same, lateral view. Scales: Fig. 49 = 0.05 mm, others = 0.1 mm. For abbreviations see text.

Genitalia: Epandrium ( Figs 53, 54 ) medium long, longer setose than in M. venustus , with longest dorsomedial and ventrocaudal seta.Anal opening large, rounded triangular. Cercus very enlarged but laterally not expanded, with anteroventrally projecting apex and micropubescent posterior edge ( Figs 53–54 ). Medandrium ( Fig. 53 ) small, short. Gonostylus ( Figs 49, 54 ) elongate, proximally and distally broader, in the middle tapered; apex angular (cf. Fig 49 ); its outer side with sparse micropubescence; inner side with scattered setae. Hypandrium relatively slender ( Fig. 51 ); transandrium narrower than in M. venustus ; lateral sides of basal membrane longer ( Fig. 52 ) and its medial part with numerous spinulae. Pregonite ( Fig. 51 ) with tuberculiform posterior part and two groups of setae (4–7 setae anteriorly and 2–3 setae on posterior tubercle). Postgonite ( Fig. 51 ) slightly sinuous, broader, with blunt apex and 2–3 setulae (that in apical third longest); internal dark striated membrane as in M. venustus . Aedeagal part of folding apparatus with small lenticular tubercles; connecting sclerite ( Fig. 50 ) elongate, slender, sclerotised. Aedeagal complex ( Fig. 50 ) with phallapodeme more slender, with bifurcate base less asymmetrical and apex expanded ventrally. Saccus of distiphallus membranous, with basal sclerites larger than in M. venustus , with short dark blunt spines in 2 subapical groups besides fine setulae. Filum formed by 2 stripe-like sclerites, one longer and wider than other in flattened apex. Ejacapodeme small, with slender projection ( Fig. 50 ).

Female unknown.

Discussion: M. bifilum sp. n. belongs to the M. venustus -group and is closest to M. caligatus sp. n; these species share a number of synapomorphies, viz. reduced silvery stripes on frons, long ventrocaudal seta on epandrium, reduced setae on posterior tubercle of postgonite, similar spines on saccus of distiphallus. M. bifilum differs from all congeners by the dark gena without silvery microtomentum, its very broad dorsal brown pleural band, the gonostylus narrowed in the middle, and the distinctive male cercus and finely spinose basal membrane ( Fig. 52 ).

Biology: Both type specimens were caught in November.

Distribution: The species is only known from Kenya.

Figures

Figs 49–54. Margdalops bifilum sp. n., male paratype (Kenya). 49. Gonostylus, sublateral view (widest

Figs 69–71. Wings of Margdalops species. 69. M. venustus sp. n., male paratype (S. Africa), 70. M. bifilum sp. n., male paratype (Kenya), 71. M. caligatus sp. n., male paratype (Kenya). Scale = 0.5 mm.