Diopsis eisentrauti Lindner, 1962

Feijen, Hans R. & Feijen, Cobi, 2012, A new species of Diopsis L. (Diptera: Diopsidae) from South Africa and Swaziland, and brief review of African species with a large apical wing spot, African Invertebrates 53 (1), pp. 125-125 : 126-132

Diopsis eisentrauti Lindner, 1962

Figs 1, 3, 5–7, 10–14, 16, 18, 20–22

Diopsis eisentrauti: Lindner 1962: 9 ; Feijen 1989: 23, 26, 39; Feijen & Feijen 2009: 703.

Diagnosis: The species can be recognised by the vague circular groove on the frons, strong facial teeth, very small IVB (~0.5× eye stalk diameter), vague granulated structure mesally on scutum, pruinose T-cross on scutum, large rounded apical wing spot, pale ‘iridescent’ subapical band between apical wing spot and central infuscation, slender front femora, whitish apical four tarsal segments of front leg, brown terga, trapezoid ♀ sternum 7, ♀ tergum 8 and sternum 8 single sclerites, wrinkled sausage-shaped spermathecae with small tubercles, ellipse-shaped to rounded epandrium, non-articulated surstyli in lateral and posterior view club-shaped (basally strongly constricted), and (probably) low sexual dimorphism in eye span ( D ~1.0, proportion eye span/body length 1.02 in ♀ and 1.36 in ♂).

Redescription ( ♂ and ♀):

Measurements: Overall length: ♀ 7.2 mm ± SE 0.1 (range 7.0–7.4, n =3), ♂ 7.1 mm ± 0.2 (range 6.0–7.7, n =7); eye span: ♀ 7.4 mm ± 0.2 (range 7.1–7.7, n =3), ♂ 9.5 mm ± 0.4 (range 7.5–11.1, n =7); wing length: ♀ 5.4 mm ± 0.0 (range 5.4, n =2), ♂ 5.6 mm ± 0.1 (range 5.2–6.0, n =6); length of scutellar spine: ♀ 1.53 mm ± 0.01 (range 1.52–1.54, n =2), ♂ 1.50 mm ± 0.02 (range 1.45–1.57, n = 6).

Head ( Figs 1, 5): Central part glossy yellowish brown (red in Lindner’s description), ocellar tubercle dark brown; frons with vague circular groove in front of tubercle and laterally radiating minor ridges; arcuate groove slightly darker than surrounding areas; face with fine horizontal ridges (hardly visible in the Togo specimen), strong facial teeth; eye span medium sized in female (2% longer than the length of body) and very large in male (36 % longer than the length of body); rate of dimorphism cannot be determined on the few females available but is likely to be somewhat lower than in D. stuckenbergi sp.n., D ~1.0 ( Fig. 5, Table 1); stalks glossy yellowish brown, broad apical parts blackish; funiculus uniformly brown; IVB very small, about 0.45× the diameter of the eye stalk, base of IVB hardly elevated ( Fig. 1); OVB small, 1.25× the diameter of the stalk; stalks and face covered with a number of small white setulae.

Thorax ( Figs 6, 7): Collar glossy black, lateroventrally pruinose, also some pruinosity along anterior margin and on central knob; scutum glossy black with pruinose mesal band on posterior ¾ which combined with a broad transverse pruinose band gives a T-shaped cross ( Figs 6, 7), however this cross is not or hardly extending in anterior direction like in the complete cross of Diopsis cruciata (Lindner stated ‘grauer Bestäubung, die kreuzförmig ist,’ but also the holotype has only a T-cross), width of the transverse band varies from broad in the holotype to rather narrow with two short symmetrical interruptions in a Congo ♂ ( Fig. 7), between humeral calli and along mesal band a vague granulated structure; scutellum blackish brown pruinose, scutellar spines glossy brown with darker tip; pleura pruinose except for glossy anterodorsal corner and glossy central section; sterna black, pruinose; scutellar spines long and straight, almost 4× as long as scutellum; diverging under an angle of 50°; metapleural spines well developed, about ⅓ the length of scutellar spine, anterolaterally directed; thorax with some fine white setulae, especially on scutellar spines and below wing base.

Wing ( Fig. 3): Apex with large, rounded brown spot extending from r 1 to well into r 4+5 (Lindner also described the apical wing spot as proximally rounded in which he distinguished it from the more triangular spot of D. apicalis ; however, D. apicalis also has a rounded apical wing spot); pale ‘iridescent’ subapical band between apical wing spot and central infuscation; central infuscation vague, but rather large with some slightly darker sections around crossvein R–M and around anterior half of crossvein M–Cu; glabrous basal sections of wing include basal third and posterior edge of cell c, basal section of cell r 1 well proximal of junction of veins R 2+3 and R 4+5 (but no anterior edge), basal ⅔ of cell br, basal section of cell bm and basal half of cell cu p, remainder of wing covered with microtrichia; tip of vein Cu narrowing towards wing margin.

Legs: Front leg with pale brown coxa, trochanter and femur, dark brown tibia and metatarsus and distinctly whitish other tarsi (Lindner considered the white tarsal segments as a diagnostic character; there are other diopsids with strikingly white tarsal segments, but in the D. cruciata -group it is indeed a diagnostic character); mid and hind leg pale brown with blackish brown tibia 3; femur 1 slender in both sexes, proportion of length/width in ♀ 5.4 (n =1) and in ♂ 5.9 ± 0.1 (range 5.7–6.2, n= 5), on distal 0.4 of ventral side with two rows of dark tubercles, inner row in ♀ with 15.0 tubercles ± SE 0.4 (range 14–16, n = 4) and in ♂ with 15.6 tubercles ± 0.3 (range 14–17, n = 11), outer row in ♀ with 13.8 tubercles ± 0.3 (range 13–14, n =4) and in ♂ with 14.5 tubercles ± 0.4 (range 12–16, n =11).

Abdomen: Syntergum 1+2+3 glossy brown, basally some pruinosity medially, no sutures visible; other terga glossy brown, terga with sparse fine setulae; ventral preabdomen yellowish and thinly pruinose, sternum 1 more glossy; spiracle 1 in membrane, intersclerite 1–2 very narrow; sterna 4 and 5 single rectangular plates, sternum in ♂ slightly folded inward on the meson.

Female postabdomen ( Figs 10–13, 16, 18): Straight, not deflexed, terga 6, 7 and 8 single rectangular sclerites ( Fig. 10); tergum 10 with two pairs of long setulae and 3 pairs of shorter setulae; cerci rather elongate, proportion of length/width 3.2 ( Fig. 11), covered with microtrichia and a number of setulae; sternum 6 a quadrangular sclerite, sternum 7 a trapezoid sclerite more sclerotised laterally and posteriorly ( Fig. 10); sternum 8 consisting of a single quadrangular sclerite ( Fig. 16); spiracle 6 just in membrane, spiracle 7 on the edge in tergum; subanal plate pentagonal ( Fig. 12), posteriorly six pairs of setulae; spermathecae ( Fig. 13) wrinkled, sausage-shaped with a number of dispersed tiny tubercles, inner basal structure rather short compared to the long overall form; sclerotised ring of ventral vagina wall almost round with broad lateral arms ( Fig. 18).

Male postabdomen ( Figs 14, 20–22): Straight; sternum 6 almost absent, just represented by the two characteristic anterior microchaetae and two vague tiny sclerites folded inward; synsternum 7+8 very narrow, almost line like, left spiracle 7 in membrane, right spiracle 7 just touching the synsternum; epandrium ( Fig. 20) ellipse-shaped to rounded in posterior view, with about 19 pairs of setulae, covered with microtrichia; surstyli non-articulated, fused to epandrium, in lateral view ( Fig. 14) club-shaped, preapically about twice as broad as basally, smoothly rounded apically, in posterior view ( Fig. 20) distinctly club-shaped, basally constricted, apically smoothly rounded, on apical third a few sparse small setulae, apically some more setulae, on inner side on apical third a dense brush of short setulae, no microtrichia except for small patch near base; surstyli interconnected via slender processus longi; cerci simple, somewhat rectangular, tapering basally, rather broad, proportion length/width 2.2, covered with microtrichia and setulae; phallapodeme rather slender ( Fig. 21), anterior arm with smoothly rounded corners, anterior arm just marginally longer than posterior arm; ejaculatory apodeme broadening apically fan-shaped to axe-shaped ( Fig. 22).

Distribution and habitat: Cameroon, Democratic Republic of Congo, Gabon and Togo. From the collection data follows that this Diopsis occurs in Afromontane forests at altitudes between 500 and 1500 m.

Holotype: ♀ (not ♂ as stated by Lindner, 1962) CAMEROON: Soppo [ 4°09'N 9°17'E, ca 700 m], 10.i.1954, M. Eisentraut ( SMNS).

Other material examined: CAMEROON: 1♂ 1♀ Djoungolo, Villa Carde S / Nyong , 22.v.1963, L. Seegers ( ZSM) ; 1♂ Kumba , 26.x.1949, H. Oldroyd ( BMNH) ; 2♂ Yaoundé, N’Kolbisson [ ca 750 m], 19.vii.1967, 9.viii.1967, L. Matile ( MNHNP) ; TOGO: 1♀ R. des Plateaux, Pte. Baumann (= Mt Agou ), 986 m, G.G.M. Schulten ( RMNH) ; GABON: 1♂ entre Lebamba & M’bigou, Forêt et Lisière, Mission M. Donskoff et J. Le Breton, 600 m ( RMNH) ; DEMOCRATIC REPUBLIC OF CONGO: 2♂ Mwenda, Mt Ruwenzori , 13 xii.1948, 1400 m, forest, J.C. Bradley ( AMNH) ; 1♂ Kasongo , viii.1959, P.L.G. Benoit ( RMNH) .