Margdalops signatus, 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 : 14-18

Margdalops signatus sp. n.

( Figs 24–35 , 68 )

Type material: Holotype male, labelled: ‘ Karen, Nairobi, Kenya. 31 May 1973. D. K. McAlpine’ ( AMSA, intact) . Paratypes: KENYA: 3 males 6 females, same data as as holotype ( AMSA, 1 male 1 female SMOC). Five paratypes with genit. prep .

Etymology: Named ‘ signatus ’ (L. = marked, signated) because of the distinctive mesonotal pattern.

Description: Male.

Total body length 2.02–2.22 mm. Body brown and yellow.

Head: Slightly longer than high. Occiput with silvery microtomentose stripes wide, almost meeting medially. Frons with pattern similar to that of M. angustus , but frontal triangle reaching to anterior two-thirds of frons and silvery white stripes wider, particularly anteriorly. Ocellar triangle slightly convex, shiny. Face ochreous, medially ochreous brown. Gena and postgena dirty whitish yellow, sparsely silvery microtomentose and gena with narrow brown ventral margin. Mouthparts yellow. Chaetotaxy as in M. venustus , but pvt longer and crossed; vti less convergent and shorter than vte; 1–2 pairs of microsetulae in front of frontal triangle; vibrissal chaetotaxy as in M. microcercus , thus with 2 subvibrissae, 1 short anterior and 1 longer posterior. Eye less ovoid, with longest diameter only 1.25–1.3 times as long as shortest one. Gena slightly widened posteriorly; its minimum depth about 0.07 times as long as shortest eye diameter.Antenna ochreous to ochreous brown, anteroventral half of 1st flagellomere pale yellow. Arista about 1.9 times as long as antenna, long ciliate.

Thorax: Paler than in all congeners. Mesonotum brown but with broad ochreous orange longitudinal band between dorsocentral lines, often extended on disc of scutellum; usually there is a narrow brown medial stripe in anterior third of the latter band; humeral and notopleural areas ochreous. Pleural areas with dorsal brown band narrow; otherwise yellow. Chaetotaxy similar to M. venustus , but characterised by shorter prs and, particularly, by weak anterior dc (shorter and inserted more posteriorly than in M. microcercus ); medial row of ac setulae almost reaching to posterior dc. Legs yellow to pale yellow. Pedal chaetotaxies as in M. venustus ; f 3 with posteroventral row of 17–18 setae, 5–6 of them shortened and thickened. Wing pattern ( Fig. 68 ) as in M. angustus . R 4+5 and M subparallel, distally very slightly or hardly convergent. Discal cell broad as in M. angustus , with r-m situated slightly anterior to its middle. CuA 1 long, straight. Wing measurements: length 2.22–2.46 mm; width 0.63–0.73 mm, Cs 3: Cs 4 = 2.31–2.60, r-m/dm-cu: dm-cu = 3.20–3.70. Haltere brown with blackish brown knob.

Abdomen: Dark brown, sterna brown. Preabdominal terga as in M. microcercus ; T6 very short, transverse, weakly sclerotised and pale pigmented. S3–S4 slightly longer than wide; S5 wider than long and posteromedially emarginate. S6 and S7 very short.

Genitalia: Epandrium ( Figs 24, 25 ) short, very broad, shortly setose, but with 1 long robust dorsomedial seta and 1 long ventrocaudal seta.Anal opening rounded triangular. Cercus long, slender, with ventral half somewhat dilated, apically rounded; its surface largely microtomentose ( Figs 24, 25 ). Medandrium ( Fig. 24 ) wide, medially very short. Gonostylus ( Figs 25, 26 ) simple, flat, wider proximally, narrower distally, with apex broadly rounded; its outer side micropubescent; inner side with scattered setae. Hypandrium moderately developed, simple ( Fig. 27 ); transandrium straight and simple; lateral sides of basal membrane weakly sclerotised, but apically provided with small, dark sclerotised process ( Figs 27, 28 ). Pregonite ( Fig. 27 ) posteriorly indistinctly projecting, with two groups of setae (3–4 in anterior, 2 in posterior group). Postgonite ( Fig. 27 ) very slender, flat, slightly curved, apically acute and bearing 1 anterior seta in basal third; sclerite at base of postgonite present but small; membrane attached internally to postgonite finely striated. Aedeagal part of folding apparatus provided with hyaline lenticular tubercles and dark undulate striae; connecting sclerite ( Fig. 29 , cs) very slender, weakly sclerotised. Basal membrane ( Fig. 28 ) with small transverse tubercles (in the middle) and fine spinulae (ventrally). Aedeagal complex ( Fig. 29 ) with moderately developed phallapodeme with shortly bifurcate base and laterally dilated apex. Saccus relatively short, with membranous dilated distal half (apically with a group of hyaline tubercles, basally with 2 groups of short spines) and narrower proximal half reinforced with a pair of dark sclerites in addition to a somewhat ventrally projecting base. Filum robust, formed by 2 completely fused sclerites and bearing several unpigmented projections, including 1 slender in the middle and 3 (1 flat, 2 slender) on apex. Ejacapodeme larger, with terminally clubbed projection ( Fig. 29 ).

Female differs from male as follows:

Total body length 2.34–2.66 mm.

Face pale brown; gena, postgena and mouthparts darker yellow. Antenna with 1st flagellomere darker, ochreous brown, including apex, often darker than pedicel. Usually 2 pairs of microsetulae in front of frontal triangle. f 3 posteroventrally finely setulose. Wing measurements: length 2.58–2.90 mm; width 0.73–0.89 mm, Cs 3: Cs 4 = 2.38– 2.72, r-m/dm-cu: dm-cu = 3.30–3.92.Abdomen with preabdominal terga more transverse and sterna narrower. S3 1.5 times as long as wide, narrower than S4; S5 the widest and about as long as broad.

Postabdomen ( Figs 30, 31 ) moderately long. T6 wider than T7, with short thick setae in posterior two-thirds. S6 narrower than S5, as long as wide, pale pigmented, with membranous margins and sparsely setose. T7 long, dorsomedially short due to anteromedial emargination, with thick setae in posterior two-thirds. S7 longer than broad, dark pigmented ( Fig. 31 ), with fine setae in posterior two-thirds, those in posterior row long. T8 broad, distinctly transverse, posteromedially emarginate, with fine setae in posterior half. S8 dark, smaller than T8, subcordate, shortly setulose. T10 small, pentagonal, dark only along anterior and lateral margins, with microtomentum restricted to central light area. S10 longer than T10, semicircular. Genital chamber ( Figs 33, 34 ) with only 1 pair of crooked sclerites (others membranous) and 1 ventral ring-shaped sclerite. Ventral receptacle ( Fig. 34 ) subcylindrical, proximally ringed and weakly sclerotised, apically narrowed and merging into apical, recurved and sinuate vermicular projection. Spermathecae 1+1 ( Figs 32, 35 ) subspherical, similar to those of M. microcercus , but both subequal, with short cervix. Cercus ( Fig. 30 ) short but robust, dark pigmented.

Discussion: M. signatus sp. n. belongs to the M. angustus -group. It can be distinguished from other species of the group as well as remaining congeners by the ochreous orange band between the dorsocentral lines on the mesonotum. It is further diagnosed by 2 subvibrissae (otherwise only known in M. microcercus sp. n.); a very broad epandrium; male cercus dilated in ventral half; ventrolateral sclerotisation of basal membrane; armature of of saccus and filum of distiphallus; the transverse female T8; and reduced number of female internal sclerites.

Biology: The entire type series was collected in May.

Distribution: The species is known only from Kenya.

Figures

Figs 24–29. Margdalops signatus sp. n., male paratype (Kenya). 24. External genitalia, caudal view. 25. Same, lateral view. 26. Gonostylus, sublateral view (widest extension). 27. Hypandrium and associated structures, lateral view. 28. Transandrium, caudal view. 29.Aedeagal complex, lateral view. Scales: Fig. 26 = 0.05 mm, others = 0.1 mm. For abbreviations see text.

Figs 30–35. Margdalops signatus sp. n., female paratype (Kenya). 30. Postabdomen, dorsal view. 31. Same, ventral view. 32. Spermatheca. 33. Internal sclerites, ventral view. 34. Genital chamber with internal sclerites, lateral view. 35. Spermatheca. Scales: Figs 30, 31 = 0.1 mm, others 0.05 mm. For abbreviations see text.

Figs 66–68. Wings of Margdalops species. 66. M. microcercus sp. n., female paratype (Kenya). 67. M. angustus sp. n., female pararype (S. Africa). 68. M. signatus sp. n., female paratype (Kenya). Scale = 0.5 mm.