Eumerus nadoosheni Gilasian & van Steenis, 2022

Gilasian, Ebrahim, van Steenis, Jeroen & Parchami-Araghi, Mehrdad, 2022, Six new species of the genus Eumerus Meigen, 1822 from Iran (Diptera, Syrphidae), Journal of Insect Biodiversity and Systematics 8 (3), pp. 483-512 : 487-491

Eumerus nadoosheni Gilasian & van Steenis sp. nov. ( Figs 4, 5B, D, F)

https://zoobank.org/ urn:lsid:zoobank.org:act:AE685D51-377B-4C56-B001-78885BBB67B2

Differential diagnosis. This species is closely related to E. acuticornis Sack, 1933 based on its isosceles ocellar triangle, yellowish-orange coloration of tergum IV in posterior 1/4, almost bare eyes, square basoflagellomere compared to rectangularly shaped in E. acuticornis ; scutum anteromedially with two wide pollinose vittae (absent in E. acuticornis ); pollinose maculae on abdominal tergum IV short and almost straight while strongly oblique and long in E. acuticornis ; sternum IV with median U–shaped incision posteriorly compared to V–shaped in E. acuticornis ; legs mostly reddish, tibiae with a very narrow median dark ring, metabasitarsus entirely red, comparing distinctly darker legs in E. acuticornis ; oblique maculae on abdominal tergum IV almost straight comparing skewed oblique maculae in E. acuticornis . Furthermore the species E. acuticornis seems to be endemic to southern Mongolia.

Material examined. Holotype: IRAN ♂ (pinned), Yazd prov., Ardakan to Chah Afzal rd., June –2018, reared larva found on Cistanche sp. , Ali Jafari Nadooshen ( HMIM) . Paratypes: 3 ♀♀: same data as holotype , 2 ♀♀ ( HMIM) , 1♀ ( JSA) .

Etymology. This species is dedicated to Dr. Ali Jaafari Nadooshen, who collected the material. The specific epithet is a noun in the genitive case.

Description Male. Body length: 6.0 mm; wing length: 4.3 mm. Head ( Figs 4C, D). Eyes almost bare, holoptic; eye contiguity almost 0.75 times as long as frontal triangle; face white pilose, densely covered with white pollinosity; frontal and vertical triangles almost equal in length, white pollinose with white pile; head in frontal view about 2.8 times as wide as face; ocellar triangle isosceles, shiny black, white pilose; distance between posterior ocelli and posterior margin of eye about 0.75 times as long as ocellar triangle; occiput grey pollinose; frontal triangle 1.8 times as wide as ocellar triangle; vertex at posterior corner of eyes about 1.1 times as wide as vertex over posterior ocelli; head in dorsal view 4.4 times as wide as vertex at posterior corner of eyes; scape, pedicel and arista brownish-orange; basoflagellomere orange, square-shaped and pointed apicoventrally; arista 1.9 times as long as basoflagellomere ( Fig. 4E).

Thorax. Scutum and scutellum shiny black with green lustre, short whitish pilose; scutum with two median wide grey pollinose vittae ( Fig. 4A); scutellum with marginal rim; pleurae shiny black, covered with whitish pile except for bare meron and katepimeron; metasternum pilose. Legs. Short yellowish-white pilose; femora mostly brownish-black, orange apically; tibiae black in apical half; tarsi orange; metafemur strongly enlarged, about 2.5 times as long as wide ( Fig. 4F), ventral pile short and about 1/3 of the width of metafemur; anteroventral and posteroventral margins of metafemur with an apical row of six and nine black setae respectively. Wing. Hyaline; entirely microtrichose; calypters yellowish-white; halter yellowish-orange. Abdomen ( Fig. 4G). Predominantly brownish-black with short whitish pile; posterior margin of tergum IV yellowish- orange; terga II–IV with a pair of slightly oblique white pollinose maculae; maculae on tergum IV short and almost straight; sternum IV trapezoidal, with median U-shaped incision posteriorly ( Fig. 4H). Male genitalia. Hypandrium simple; aedeagal apodeme in lateral view as in Fig. 5F; epandrium, cercus, posterior and anterior lobes of surstylus as in Figs 5B, D.

Female. Body length: 4.5–6.1 mm; wing length: 3.5–4.5 mm. Similar to the male except for sexual dimorphism and for the following characters: Distance between posterior ocelli and posterior margin of eye about as long as ocellar triangle; vertex at posterior corner of eyes about 0.9 times as wide as vertex over posterior ocelli; head in dorsal view about 5.1 times as wide as vertex at posterior corner of eyes; basoflagellomere slightly longer than male; arista 1.4 times as long as basoflagellomere; tergum IV almost entirely black.

Distribution. Iran.

Remarks. The type material of Eumerus acuticornis was not available for this study. The original description (Sack, 1933) and the description in Stackelberg (1961) were used to identify this species.