Microdon (Megodon) planitarsus Keiser

Reemer, Menno & Bot, Sander, 2015, Six new species of Microdon Meigen from Madagascar (Diptera: Syrphidae), Zootaxa 4034 (1), pp. 127-147 : 143-145

Microdon (Megodon) planitarsus Keiser

( Figs 49–55 )

Microdon planitarsus Keiser, 1971: 245 .

Diagnosis. One of the two known species of the subgenus Megodon , which differs from other species of Microdon in the occiput, which is narrow and evenly wide over its entire length, and also by the wide and deep longitudinal groove in the male hind basitarsomere. Microdon planitarsus differs from M. stuckenbergi by its smaller size (6–9 mm) and the much smaller scutellar calcars ( Fig. 49 ).

Type material studied. HOLOTYPE. – Male. Label 1 (red): " Typus "; label 2: " Madagascar Centre, Anjavidilava 2020 m, Andriagitra Ambalavao, 17-21.I.58. B. Stuckenberg"; label 3: " Microdon planitarsus Keiser "; label 4: "Muséum Paris, Microdon planitarsus Keiser 1971 ". Coll. MNHN.

Additional material studied. Madagascar. Fianarantsoa Prov, Belle Vue, 1.2 km S Ranomafana National Park entrance, Malaise in rain forest, leg. R. Harin'Hala & M.E. Irwin: 28.I.–4. II.2002, 1 male & 1 female (coll. CAS); 16.–28.V.2003, 1 male & 1 female (coll. RMNH); 23.IV.–4. V.2003, 1 male (coll. CAS). Fianarantsoa Prov., 17 km W Ranomafana, Vohiparara, Ranomafana National Park, Malaise in rain forest, leg. R. Harin'Hala & M.E. Irwin: 24.XII.2001 – 2.I.2002 (coll. CAS), 1 female; 10.–14.I.2002 (coll. CAS), 1 female; 14.–21.I.2002, 1 male (coll. CAS), 1 female (coll. CSCA); 22.–29.IV.2002, 1 female (coll. CSCA). Fianarantsoa Prov., ANGAP Hqt., Ranomafana (town), Malaise nr stream, 6.–15.XII.2001, leg R. Harin'Hala & M.E. Irwin: 1 male (coll. RMNH). Fianarantsoa Prov., Ranomafana National Park, radio tower at forest edge, 2.–10.XII.2005 and 7.–16.XII.2005, leg. M. Irwin & R. Harin'Hala: 1 male, 2 females (coll. CSCA). Fitovavy, Fitovinany Region, Ifanadiana District, 12 km W of Ranomafana, 14.–21.XII.2007, leg. M. Irwin & R. Harin'Hala: 1 female (coll. CSCA).

Redescription of male holotype (except where stated otherwise). Body size: 9 mm (additionally studied males: 6–9 mm). Head. Face shining brownish black; entirely black pilose (yellow pilose in additionally studied specimens). Genae black, black pilose. Oral margin laterally not produced. Frons black; black and yellow pilose. Vertex black; yellow pilose. Occiput narrow over entire length; black; yellow pilose; greyish pollinose. Eye bare. Antennal fossa slightly higher than wide. Antenna yellowish brown; antennal ratio approximately as 3:1:3. Arista brown, about as long as basoflagellomere. Thorax. Mesoscutum black with brownish margins; yellow pilose. Postpronotum, postalar callus and scutellum brown; yellow pilose. Scutellum with two apical calcars of about 1/4 of length of scutellum. Pleurae blackish brown. Anepisternum with shallow sulcus separating anterior from posterior part; anterior part yellow pilose, posterior part black pilose, with widely bare part in between. Anepimeron entirely yellow pilose. Katepisternum yellowish pilose dorsally; bare ventrally. Katatergum long, black microtrichose, anatergum short microtrichose. Calypter and halter yellow. Wing. Hyaline, slightly brownish; entirely microtrichose, except bare on narrow basomedian part of alula. Legs. Yellowish brown. Femora black pilose. Tibiae black pilose anteriorly, yellow pilose posteriorly. Tarsae yellow pilose, except first tarsomere of hind leg dorsally black pilose. Coxae and trochanters brown; black pilose on front and middle leg, white pilose on hind leg. Abdomen. Tergites 2–3 yellowish with brown lateral margins and a narrow dark median line. Tergite 4 brown with faint yellowish maculae at anterior margin and vaguely yellow along posterior margin. Tergite 2 yellow pilose with some black pile laterally. Tergite 3 black pilose. Tergite 4 black pilose with yellow pile posteriorly. Sternite 1 brown; bare. Other sternites yellow; yellow pilose. Genitalia as in Fig. 53 .

Female. Body size 7–9 mm. As male, except for usual sexual dimorphism and colouration of tergites: dark brown except for pale brown lateral margins, especially on tergite 2 ( Fig. 55).

Variation. The additionally studied specimens differ from the holotype in the pale pilosity of the face and overall paler colouration ( Fig. 54 ). Otherwise, they are very similar in morphology, also in the male genitalia. They were collected roughly 70 km from the type locality.

Figures

FIGURE 54. Microdon (Megodon) planitarsus Keiser. Male (1.2 km S Ranomafana Park entrance, 16. – 28. V. 2000 (RMNH )). Abdomen dorsal.

FIGURES 49 – 53. Microdon (Megodon) planitarsus Keiser. Male holotype. 49. Habitus dorsal. 50. Habitus lateral. 51. Head frontal. 52. Head lateral. 53. Genitalia lateral.