Eumerus effossus 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 : 493-496

Eumerus effossus Gilasian & van Steenis sp. nov. ( Figs 9, 12A, C, E)

https://zoobank.org/ urn:lsid:zoobank.org:act:49ED024D-FA90-4FC8-89A6-E336531AD59E

Differential diagnosis. This species is closely related to E. incilis for its deep excavation on metabasitarsus and two apicoventral black spina on metatibia. It is separated from E. incilis by the following characteristics:

The dorsal pilosity of metabasitarsus very short, with longer dense black subappressed setae-like pile apically (in E. incilis the entire dorsal surface of metabasitarsus with medium long pile); legs and basoflagellomere in male extensively brownish compared to predominantly black in E. incilis ; abdominal tergum II white pollinose anterolaterally with a pair of oblique pollinose maculae (in E. incilis only with oblique pollinose maculae); sternite IV in male rounded at posterior corners with a shallow median U-shaped incision (compare with Fig. 25 in Smit et al., 2017, page 583 for sternite IV of E. incilis ).

The species E. effossus Gilasian & van Steenis sp. nov. is incorporated into the identification key to the species of the E. obliquus species group provided by Ricarte et al. (2020) as follows:

4 Eye with short sparse pile; metabasitarsus, in male, with a small basal tooth in the sulcus [see figure 30

in Smit et al. (2017)].......................................................................................................................................... E. vestitus — Eye bare; metabasitarsus, in male, without teeth in the sulcus [see figure 30 in Smit et al. (2017)]. ..... 4 (a)

4 (a) Dorsal pilosity of metabasitarsus very short, with longer dense black subappressed setae-like pile apically; metabasitarsus in male yellowish-orange; abdominal tergum II white pollinose anterolaterally with a pair of oblique pollinose maculae. ................................................... E. effossus sp. nov.

— Dorsal pilosity of metabasitarsus with medium long pile; metabasitarsus in male predominantly black; abdominal tergum II only with oblique pollinose maculae. ............................................................ E. incilis

Etymology. The specific epithet “effossus ”, Latin for excavated, refers to the deeply excavated metabasitarsus, which is only shared with E. incilis . It is to be treated as a noun in apposition.

Material examined. Holotype: IRAN ♂ (glued to a card point), Sistan & Balouchestan prov. , Bampour, Agricultural Research Center, 27°11′56″N 60°29′52″E, 4 March–21 May 2016, 525 m, Malaise trap, F.

Basavand ( HMIM). Paratypes, 4 ♀♀: 1 ♀, (glued to a card point), Sistan & Balouchestan prov., Sarbaz , Sefid Sang village , 28°38′21.4″N 61°16′19.9″E, 10 March–15 May 2017, 903 m, Malaise trap, F. Basavand ( HMIM) ; 2 ♀♀, (glued to a card point), Kerman prov., Zeh-Kaloot, Jazmourian Wetland, Chah-Alam village , palm grove, 27°44′43.2″N 58°34′37″E, 30 May–10 September 2017, 387 m, Malaise trap, Mehrdad Parchami-Araghi ( HMIM) ; 1 ♀, same as previous ( JSA) .

Description Male. Body length: 3.8 mm; wing length: 3.7 mm. Head ( Figs 9C, D). Eyes bare, holoptic; eye contiguity 0.65 times as long as frontal triangle; face white pilose, densely covered with white pollinosity; frontal and vertical triangles almost equal in length, with white pollinose and white pile; head in frontal view about 3 times as wide as face; ocellar triangle isosceles, white pollinose on about anterior half with white pile; distance between posterior ocelli and posterior margin of eye about 0.5 times as long as ocellar triangle; occiput grey pollinose; frontal triangle twice 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 5.7 times as wide as vertex at posterior corner of eyes; antenna brownish-orange, arista 1.5 times as long as basoflagellomere ( Fig. 9E). Thorax. Scutum with long white pile, predominantly white pollinose except for two median brownish vittae and four semi-square brownish spots (two anteriorly and two posteriorly located to the transverse suture) ( Fig. 9A); scutellum brownish, with long white pile, densely white pollinose at posterior margin; pleurae brownish, covered with whitish pile except for bare meron and katepimeron; metasternum pilose. Legs. Yellowish-orange with yellowish-white pile; metafemur enlarged, about 2.7 times as long as wide ( Fig. 9F), ventral pile about 1/3 times as wide as metafemur; anteroventral and posteroventral margins of metafemur with an apical row of 8 and 4 black setae respectively; metatibia with two apicoventral black spina; metabasitarsus with an excavation, dorsal pile very short, with long dense black subappressed setae-like pile apically ( Fig. 9G). Wing. Hyaline; entirely microtrichose; calypters yellowish-white; halter yellowish-orange. Abdomen ( Fig. 9H). Brownish-orange with short whitish pile; terga II–III each with a pair of oblique pollinose fasciae, narrowly connected medially; tergum II anterolaterally and tergum III laterally white pollinose; tergum IV predominantly white pollinose except for a narrow anterior shiny brownish margin, sternum IV rounded at posterior corners, with a shallow median U- shaped incision posteriorly. Male genitalia. Hypandrium simple; aedeagal apodeme in lateral view as in Fig. 12E; epandrium, cercus, posterior and anterior lobes of surstylus as in Figs 12A, C.

Female. Body length about 5.5–7.1 mm; wing length: 4.4–6.0 mm. Similar to the male except for the sexual dimorphism and for the following characters: Darker than male; head in dorsal view about 5 times as wide as vertex at posterior corner of eyes; metabasitarsus unmodified, without excavation.

Comment. Considering the presence of a single male specimen, we interpret the existing different coloration between the sexes more likely as a result of discoloration of the male due to preservation in ethanol than a morphological sexual dimorphism.

Distribution. Iran.

Remarks. The type material of Eumerus incilis was not available for this study. The original description ( Smit et al., 2017) and the paper on the E. obliquus group ( Ricarte et al., 2020) were used to identify this species.