Review of the Eumerus tricolor species group (Diptera: Syrphidae) in Iran, with description of six new species

The species of the Eumerus tricolor species group in Iran are reviewed. Six species new to science are described from Iran, i.e., Eumerus atricolorus Gilasian & van Steenis sp. nov., E. brevipilosus Gilasian & van Steenis sp. nov., E. chekabicus Gilasian & van Steenis sp. nov., E. ovoformus Gilasian & van Steenis sp. nov., E. pilosipedes Gilasian & van Steenis sp. nov. and E. vallicolus Gilasian & van Steenis sp. nov. Three species, E. hissaricus Stackelberg, 1949, E. longitarsis Peck, 1979 and E. richteri Stackelberg, 1960, are newly recorded from Iran. Photographs of the species as well as illustrations of the male genitalia of the new species and closely related species are provided. An identification key to the males of the Iranian Eumerus tricolor species group is presented. A row of long posterodorsal setae on the wing vein costa basally is presented and argued as a new diagnostic morphological character for the entire Eumerus tricolor species group.


Introduction
The genus Eumerus Meigen, 1822 (Syrphidae: Merodontini) with more than 300 described species is one of the most diverse genera of hoverflies, which largely inhabit arid and semi-arid regions of the world (Grković et al. 2019a;Mutin 2019). Adults of Eumerus are distinguishable among syrphid genera by the recessive, biangulate wing vein M 1 in addition to their usually black or blackish-red aspect with greyish pollinosity of abdominal terga. They are fast flying with a visiting preference for flowers belonging Photoshop CS2. To study the male genitalia of the specimens, we gently removed the whole abdomen and heated it at 85°C in a 10% KOH solution for 15-20 minutes. The abdomen was later washed in distilled water and briefly put in glacial acetic acid to neutralize the base. Then, the genitalia were detached from the abdomen and placed in a microvial containing glycerin as a preservative, and pinned below the source specimen.
Label data of specimens are given verbatim, within double quotation marks. Each line on a label is separated by a single forward slash (/) and labels are separated by a double forward slash (//). The morphological terminology used in this paper follows Thompson (1999) for external morphology and Doczkal (1996) for the male genitalia. The measurements were made using a micrometer as follows: overall length of specimens (in mm) is measured in lateral view from the anterior margin of the head, excluding the antenna, to the end of the abdomen; length of basoflagellomere is measured from its joint to pedicel dorsally and width of basoflagellomere is measured at its maximum width (Fig. 11G). The following measurements are done as explained in  and repeated here: width of head in frontal and dorsal views is measured at its maximum width; width of face is measured below the antennae; width of ocellar triangle is measured over the posterior ocelli dorsally; length of ocellar triangle is measured from the anterior end of the anterior ocellus to the midline posterior of the posterior ocelli; length of frontal triangle is measured from the anterior corner of the eye contiguity to the posterior corner of the lunule in dorsal view; length of vertical triangle is measured from the posterior corner of the eye contiguity to the anterior ocellus in dorsal view; the eye contiguity is the length in between the previous two measurements; width of vertex in dorsal view is measured between the posterior corner of the eyes (a) and over the posterior ocelli (b).

Diagnosis of the Eumerus tricolor species group
The Eumerus tricolor species group can be identified by the combination of the following characters: basoflagellomere radially furrowed, apico-laterally with clearly demarcated, ellipsoidal fossa ( Fig. 11A-I); katepisternum ventrally, medially and dorsally pilose (as in character states 44A:0 and 44B0:1 and related figures in van Steenis & Wyatt 2020); wing vein costa with a row of long posterodorsal setae basally (Fig. 8F); terga often more or less red coloured; anterior surstylus lobe undeveloped (Figs 18A-F, 19A-E). Gilasian & van Steenis, sp. nov. urn:lsid:zoobank Head ( Fig. 13A-B). Eyes short pilose, coalescent at one point; face nearly parallel-sided, mostly shiny black, weakly grey pollinose at lateral margin and covered with long whitish pile; frontal triangle predominantly shiny black, weakly grey pollinose laterally and with dense whitish pile; head in frontal view about 3.3 times as wide as face; frontal triangle about 1.4 times as long as vertical triangle; vertical triangle mostly shiny black, weakly pollinose laterally and with whitish pile; ocellar triangle almost equilateral; ocellar triangle weakly pollinose, with whitish pile, and nearly as long as vertical triangle; distance between posterior ocelli to posterior margin of eye about 0.65 times as long as ocellar triangle; occiput grey pollinose, with light pile; frontal triangle 1.4 times as wide as ocellar triangle; vertex at posterior corner of eyes 1.35 times as wide as vertex over posterior ocelli; head in dorsal view 4.7 times as wide as vertex at posterior corner of eyes; antenna including arista entirely brownishblack; basoflagellomere rounded apicoventrally, 1.3 times as long as wide; arista 1.5 times as long as basoflagellomere (Fig. 11A).

Eumerus atricolorus
tHorax. Scutum and scutellum shiny black with short whitish pile; scutum without pollinose vittae; scutellum with marginal rim; pleurae shiny black, covered with short whitish pile except for bare meron and katepimeron; metasternum pilose. LegS (Fig. 9A). Legs predominantly shiny black except for brownish-orange apex of femora, basal narrow orange margin of tibiae and orange tarsomeres ventrally; short whitish pilose; mesotrochanter weakly pollinose and with pile ventrally; metatarsus with a short tuft of orange pile ventrally; metafemur simple, slightly enlarged, about 3.75 times as long as wide, ventral pile very short and about 1/6-1/7 of width of metafemur; anteroventral and posteroventral margins of metafemur each with a row of 10 respectively 7 black setae apically.
abdoMen. Predominantly reddish-brown; tergum I black with whitish pile laterally; terga II-IV reddishbrown, white pilose, each with a pair of oblique maculae of white pollinosity; tergum II with a median black ‛pewter chalice'-shaped vitta; tergum III with a median longitudinal black vitta on anterior half; sterna reddish-brown, yellowish pilose; sternum IV almost square, with median V-shaped incision posteriorly (Fig. 12A).

Etymology
The specific epithet 'brevipilosus' [Latin] is derived from 'brevis' (short) and 'pilosus' (pilose), in reference to the very sparse and short pile on the head, thorax and abdomen rarely seen in the genus Eumerus. Head ( Fig. 13C-D). Eyes short and white pilose, dichoptic, 2-3 ommatidia spaced; face nearly parallelsided, weakly grey pollinose, with whitish pile; frontal triangle weakly grey pollinose, entirely covered with dense and long white pile; head in frontal view 3.2 times as wide as face; frontal triangle almost 1.3 times as long as vertical triangle; vertical triangle almost entirely shiny black, with yellowish pile; ocellar triangle nearly equilateral; ocellar triangle bulging and shiny black, with black pile, about as long as vertical triangle; distance between posterior ocelli to posterior margin of eye nearly 0.8 times as long as ocellar triangle; occiput light grey pollinose, with light pile; frontal triangle nearly 1.6 times as wide as ocellar triangle; vertex at posterior corner of eyes 1.15 times as wide as vertex over posterior ocelli; head in dorsal view 4.5 times as wide as vertex at posterior corner of eyes; scape brown; pedicel yellowish brown; basoflagellomere orange, 1.2 times as long as wide; arista brown, 1.3 times as long as basoflagellomere (Fig. 11B).

Material
tHorax. Scutum and scutellum shiny black with very short yellowish pile; scutum with two narrow median pollinose vittae reaching to median suture; anterior part of median vittae semi-triangular; posterolateral part of scutum with a longitudinal row of black setulae above base of wing; scutellum with marginal rim; pleurae shiny black; anepisternum, katepisternum and anepimeron covered with short yellowish pile.
LegS (Fig. 9B). Legs shiny black, with yellowish short pile; procoxa orange apically; femora predominantly black except for orange apical tip and basal narrow orange margin, basal half and apex of tibiae orange; tarsi mostly orange except for brownish-black dorsally; metafemur simple, slightly enlarged, about 3 times as long as wide, with very short yellowish pile ventrally; anteroventral and posteroventral margins of metafemur each with a row of 8 respectively 5 black setae in about apical half.
abdoMen. Black, covered with very short yellowish pile except for long whitish pile on tergum II anterolaterally; terga II-IV each with a pair of lunulate-shaped oblique maculae of white pollinosity; sterna brown, with yellowish short pile; sternum IV rectangular, with rounded posterolateral corners and with median wide V-shaped incision posteriorly (Fig. 12B).
genitaLia (Figs 18b,20b,22b). Hypandrium simple; aedeagal apodeme in lateral view narrow and abruptly bent apically; cercus semi-rectangular; posterior lobe of surstylus in lateral view thumb-shaped apically and in dorsal view uniformly rounded apically and entirely covered with short setulae dorsally; inner accessory lobe of surstylus with short pile.
Female (Figs 5A, 8A, 9C, 11C, 14A-B) Body length: 7.8-8.2 mm; wing length: 6.0-6.5 mm. Same as male except for sexual dimorphism and for the following characters: frons shiny black, weakly pollinose laterally and with short yellowish pile; vertex at posterior corner of eyes as wide as vertex over posterior ocelli; head in dorsal view 4 times as wide as vertex at posterior corner of eyes; scutum with median narrow pollinose vittae reaching to ⅓ behind median suture; anepisternum, katepisternum and anepimeron covered with very short yellowish pile.

Distribution
Iran. Gilasian &  Head ( Fig. 13G-H). Eyes long brownish pilose, holoptic, eyes contiguity almost 0.6 times as long as frontal triangle; face nearly parallel-sided, shiny black and covered with dense and long yellowish pile; frontal triangle shiny black, entirely covered with dense yellowish pile; head in frontal view 3.75 times as wide as face; frontal triangle 1.3 times as long as vertical triangle; vertical triangle shiny black, with yellowish pile; ocellar triangle isosceles; ocellar triangle shiny black, with mix of yellowish and black pile, 1.25 times as long as wide and nearly as long as vertical triangle; distance between posterior ocelli to posterior margin of eye about 0.7 times as long as ocellar triangle; occiput light grey pollinose, with yellowish pile; frontal triangle 1.25 times as wide as ocellar triangle; vertex at posterior corner of eyes 1.3 times as wide as vertex over posterior ocelli; head in dorsal view 5.5 times as wide as vertex at posterior corner of eyes; antennae brownish-black; basoflagellomere almost as long as wide; arista about 2.2 times as long as basoflagellomere (Fig. 11D).

Eumerus chekabicus
tHorax. Scutum and scutellum shiny metallic, weakly pollinose, with long and dense yellowish pile, without median pollinose vittae; posterolateral part of scutum with two black setulae above base of wing; scutellum with marginal rim; pleurae black; anepisternum, anepiemron and katepisternum with long yellowish pile.
LegS (Fig. 9D). Legs black; metatrochanter orange at apex; metacoxa with long yellowish-white pile; pro-and mesofemora with long whitish pile posteriorly; mesofemur with short blackish pile anteriorly; metafemur simple, slightly enlarged, about 4 times as long as wide, with long whitish pile anteriorly; anteroventral and posteroventral margins of metafemur each with a row of 9 respectively 6 black setae in about apical half; pro-and mesotibiae with very short dense whitish pile dorsally and with long whitish pile posteriorly; metatibia with dense long whitish pile dorsally; metatarsus with short black pile dorsally and with tuft of dense orange pile ventrally; metasternum with long whitish pile.
abdoMen. Tergum I black with whitish pile; terga II-IV long whitish pilose, each with a pair of lunulashaped oblique maculae of white pollinosity; tergum II reddish-orange with a median black 'pewter chalice'-shaped vitta; tergum III mostly reddish-orange except median narrow black vitta; tergum IV entirely reddish-orange; sterna orange, long yellowish pilose; sternum IV rectangular, with rounded posterolateral corners and with median wide V-shaped incision posteriorly (Fig. 12C).
genitaLia (Figs 18C,20C,22C). Hypandrium simple; aedeagal apodeme wide in lateral view; posterior lobe of surstylus in lateral view narrowed toward apex, with a row of short and black setulae posteriorly and in dorsal view uniformly rounded apically with a strong median bend; inner accessory lobe of surstylus with short pile.

Female
Unknown.

Remarks
The pile colour of the face varies among the three males collected from the same locality (Haftad-Qolleh Protected Area), of which two have black and one has white pile on the face. The genitalic characters of the three differ to some extent and fail to correspond with the colour of facial pile for a certain definition of the species. We have currently concluded that the differences in the colour of the facial pile likely resulted from intraspecific variations and decided to treat them as members of E. longitarsis. Further collecting from this area has been planned to study the range of the variations in the populations to see whether or not they are identical species. Gilasian

Etymology
The specific epithet 'ovoformus' [Latin] is derived from 'ovum' (egg) and 'forma' (shape), in reference to the egg-shaped basoflagellomere which is very characteristic for this species within the genus Eumerus. Head (Fig. 16E-F). Eyes long pilose, dichoptic, 8-9 ommatidia spaced; face nearly parallel-sided, weakly grey pollinose and covered with long whitish pile; frontal triangle predominantly shiny black, weakly grey pollinose at lateral margin and with whitish pile; head in frontal view about 3.5 times as wide as face; frontal triangle about 1.3 times as long as vertical triangle; vertical triangle shiny black, with whitish pile; ocellar triangle isosceles; ocellar triangle shiny black, with whitish pile, almost  1.15 times as long as wide and about 1.2 times as long as vertical triangle; distance between posterior ocelli to posterior margin of eye about 0.9 times as long as ocellar triangle; occiput grey pollinose, with light pile; frontal triangle nearly 1.5 times as wide as ocellar triangle; vertex at posterior corner of eyes 1.6 times as wide as vertex over posterior ocelli; head in dorsal view 3.5 times as wide as vertex at posterior corner of eyes; scape and pedicel dark brown; basoflagellomere brownish-orange, egg-shaped, 1.7 times as long as wide; arista brown, 1.1 times as long as basoflagellomere (Fig. 11G).

Holotype
tHorax. Scutum and scutellum shiny black with long yellowish-white pile; scutellum with marginal rim; pleurae shiny black, covered with long yellowish pile except for bare meron and katepimeron; metasternum pilose. LegS (Fig. 9F). Predominantly shiny black except for orange apex of femora and orange basal third of tibiae; proleg predominantly with white pile except for a little black pile on basal half of profemur ventrally; mesoleg mostly with white pile except for black pilosity on mesofemur anteriorly; metaleg mostly with long whitish pile with exception of a little black pile on metafemur apicoventrally, short black pile on metatibia ventrally and a short tuft of orange pile on metatarsus ventrally; metafemur simple, enlarged, about 3.2 times as long as wide, ventral pile about ⅓ of width of metafemur; anteroventral and posteroventral margins of metafemur each with a row of 7 respectively 3 black setae apically.
abdoMen. Tergum I black with whitish pile laterally; terga II-IV each with a pair of lunulate-shaped oblique maculae of white pollinosity; tergum II orange with a median black ‛pewter chalice'-shaped vitta; tergum II mostly white pilose except for black pilosity on about posterior third, anterolateral pile on tergum II long; terga III-IV predominantly orange, tergum III with a median small black macula on anterior margin; pile on tergum III short and black dorsally, white and long laterally; tergum IV pilosity mostly white, except for short black pile anteriorly; sterna yellowish pilose; sternum I black; sterna II-IV orange; sternum IV rectangular, with median V-shaped incision posteriorly.
genitaLia (Figs 18e,20e,22e). Hypandrium simple; aedeagal apodeme as in Fig. 22E in lateral view; cercus semi-rectangular; posterior lobe of surstylus (lateral view) wide, with only long median setae, without a row of short setulae posteriorly; posterior lobe of surstylus (dorsal view) narrowed toward apex, truncated apically on outer side and with a distinct process on inner side; inner accessory lobe of surstylus with short pile.

Female
Unknown.

Male
Unknown.

Remarks
We failed to collect any specimens of this species during this study and our attempts to access the type material were not fruitful. Based on its diagnostic characters, original description (Stackelberg 1949) and the identification key (Stackelberg 1961), this species is readily separated from other Iranian species studied through this research.

Diagnosis
This species is closely related to E. kazanovzkyae except for the following characters: eyes more widely separated, nearly 3-4 ommatidia spaced (separated in E. kazanovzkyae by about 1 ommatidium); frontal triangle about 2.0-2.3 (1.75 in E. kazanovzkyae) times as long as vertical triangle; scutum and pleurae with longer pile; metafemur with longer ventral pile, about ¼-⅓ (1/8-1/7 in E. kazanovzkyae) width of metafemur; dense thick pile fringe on apicodorsal part of metatibia almost absent (long pile fringe about 3/5 width of metatibia present); metatarsus with pile fringe on entire dorsal surface (with narrower pile fringe in E. kazanovzkyae that is confined to antero-dorsal margin of metatarsus); wing slightly infuscated in apical half from anterior margin to anterior half of cell dm (strongly infuscated in E. kazanovzkyae reaching to posterior margin of wing); posterior lobe of surstylus in dorsal view uniformly rounded apically and entirely covered with setulae (truncated on inner side in E. kazanovzkyae with scattered setulae).

Description
Male (Figs 4E,7E) MeaSureMentS. Body length: 6.8-9.7 mm; wing length: 5-6.9 mm. Head ( Fig. 17A-B). Eyes pilose, dichoptic, nearly 3-4 ommatidia spaced; face nearly parallel-sided, grey pollinose and covered with dense and long yellowish-white pile; frontal triangle grey pollinose, entirely covered with dense golden pile; head in frontal view about 3.30-3.35 times as wide as face; frontal triangle about 2.0-2.3 times as long as vertical triangle; vertical triangle whitish grey pollinose, with yellowish pile; ocellar triangle isosceles; ocellar triangle shiny black, with yellowish pile, 1.10-1.15 times as long as wide and 1.4 times as long as vertical triangle; distance between posterior ocelli to posterior margin of eye nearly as long as ocellar triangle; occiput light grey pollinose, with light pile; frontal triangle nearly 2 times as wide as ocellar triangle; vertex at posterior corner of eyes 1.4 times as wide as vertex over posterior ocelli; head in dorsal view 4.5 times as wide as vertex at posterior corner of eyes; antennae yellowish-orange, arista mostly dark brown except for yellowish basal aristomeres; basoflagellomere more or less rounded apically, 1.0-1.2 times as long as wide; arista 1.7-2 times as long as basoflagellomere (Fig. 11H).
tHorax. Scutum and scutellum shiny black with long yellowish pile; scutum with two narrow median pollinose vittae reaching to ⅓-½ behind median suture and with two lateral weak pollinose vittae viewed  (Becker, 1913), Chekab Valley, Iran (HMIM). E. E. ovoformus Gilasian & van Steenis sp. nov., holotype (HMIM). F. E. richteri Stackelberg, 1960, Lar, Iran (HMIM). Scale bars = 0.1 mm. dorsally; anterior part of median vittae semi-triangular; posterolateral part of scutum with a longitudinal row of setulae above base of wing; scutellum with marginal rim; pleurae black, weakly pollinose and covered with long yellowish pile except for bare anterior parts of anepisternum and katepisternum, meron and posterior part of anepimeron; metasternum pilose. LegS (Fig. 10B-C). Predominantly shiny black; apical tip of femora orange, pro-and mesofemora sometimes orange in apical ⅓-½, metafemur rarely orange in apical ¼-⅓; basal half of pro-and mesotibia and basal third of metatibia orange; pro-and mesotarsus orange, connecting parts of tarsomeres black; metatarsus brownish-black; proleg with yellowish pile; mesoleg predominantly with yellowish pile except for black pilosity anteriorly; mesotibia and tarsomeres of mesotarsus with apical black setulae anteriorly; metacoxa with dense yellowish pile; metafemur simple, slightly enlarged, about 4 times as long as wide, with long yellowish pile ventrally, ventral pile 1/5-¼ of width of metafemur; anteroventral and posteroventral margins of metafemur each with a row of 10 respectively 6 black setae in about apical half; metatibia black pilose except for a little yellowish basal short pile dorsally; apicodorsal pile of metatibia about ⅓ of width of metatibia; metatarsus with long black pile fringe which occupies entire dorsal surface of tarsomeres, other parts of metatarsus with brown pile.
Wing. Wing entirely microtrichose, slightly infuscated in apical half from anterior margin to anterior half of cell dm, calypters yellowish; halter yellowish-orange.
abdoMen. Tergum I black with whitish pile laterally; terga II-IV each with a pair of lunulate-shaped oblique maculae of white pollinosity; tergum II orange with a median black ‛pewter chalice'-shaped vitta; tergum II mostly white pilose except for black pilosity on about posterior third, anterolateral piles on tergum II dense and long; terga III-IV entirely orange with mostly black pile except for white pile on their oblique maculae; sterna yellowish short pilose; basal half of sternum I black; apical half of sternum I and sterna II-IV orange; sternum IV rectangular, with rounded posterolateral corners and with median wide incision posteriorly (Fig. 12E).

Female
Unknown.

Diagnosis
Eyes pilose (Fig. 13I); males dichoptic, distance between eyes less than width of ocellar triangle; basoflagellomere black; scutum and scutellum shiny metallic, weakly pollinose; scutum entirely and evenly pilose, pile on scutum very short (Fig. 8E), shorter than combined length of two basal segments of arsita; legs predominantly black; metafemur slightly enlarged; tibiae black except for narrow basal orange margin; wing hyaline, entirely covered with microtrichia; abdomen predominantly orange. Head (Fig. 17G-H). Eyes short yellowish pilose, dichoptic, 5-6 ommatidia spaced; face nearly parallelsided, shiny black and covered with short yellowish-white pile; frontal triangle black, weakly pollinose and covered with dense whitish pile; head in frontal view 4.3 times as wide as face; frontal triangle 1.6 times as long as vertical triangle; vertical triangle shiny black, with brownish pile; ocellar triangle isosceles; ocellar triangle shiny black, with blackish pile, 1.1 times as long as wide and 1.4 times as long as vertical triangle; distance between posterior ocelli to posterior margin of eye about 0.6 times as long as ocellar triangle; occiput light grey pollinose, with yellowish pile; frontal triangle 1.25 times as wide as ocellar triangle; vertex at posterior corner of eyes 1.2 times as wide as vertex over posterior ocelli; head in dorsal view 5.3 times as wide as vertex at posterior corner of eyes; antennae brownish-black; basoflagellomere almost 0.9 times as long as wide; arista about 2 times as long as basoflagellomere (Fig. 11I).

Material examined
tHorax. Scutum and scutellum shiny black, with relatively long white pile, without median pollinose vittae; posterolateral part of scutum with a longitudinal row of black seulae above base of wing; scutellum with marginal rim; pleurae shiny black; anepisternum, anepiemron and katepisternum with short whitish pile.
LegS (Fig. 10D). Predominantly black, short yellowish-brown pilose; apex of femora and basal narrow margin of tibiae orange; metafemur simple, narrow, about 4 times as long as wide; anteroventral and posteroventral margins of metafemur each with a row of 11 respectively 6 black setae in about apical half; metatarsus with tuft of dense orange pile ventrally.
abdoMen. Tergum I black with short blackish pile; tergum II mostly orange except for anterior black margin and median black vitta not reaching posterior margin of segment; tergum II yellowish pile except for short blackish pilosity on its posterior third; tergum III entirely orange, mostly short blackish pile except for whitish pile on its white maculae; tergum IV black, with mostly short whitish pile except for short black pile on its anterior and posterior margin; sterna short yellowish pilose; sternum I black in anterior half and orange in posterior half; sterna II and III orange; sternum IV black, rectangular, with rounded posterolateral corners and with median wide V-shaped incision posteriorly (Fig. 12F).
genitaLia (Figs 19d,21d,23d). Hypandrium simple; aedeagal apodeme relatively narrow in lateral view; posterior lobe of surstylus in lateral view sharply extending outward posteroventrally, with a longitudinal row of short and black setulae posteriorly, with a few short median setulae and with 2-3 setae anteriorly, posterior lobe of surstylus in dorsal view uniformly rounded apically, almost balloonshaped, covered with short setulae; inner accessory lobe of surstylus with short pile.

Female
Unknown.

Distribution
Iran.

Identification key to the males of the Eumerus tricolor species group in Iran
Females are not included in the following key because they are either unknown for most of the species or morphologically difficult to separate from each other. Iran, i.e., Eumerus coeruleus, E. jacobsoni, E. persarum and E. persicus (Stackelberg 1961;Peck 1988;Barkalov & Gharali 2004;Gilasian & Barkalov 2004;Kamangar et al. 2004;Bahirai et al. 2014).
The species Eumerus zarudnyi Stackelberg, 1949, which was described from western Iran, is considered as a synonym of E. falsus by Peck (1988). In their catalogue of the Iranian Syrphidae, Dousti & Hayat (2006) erroneously added E. lunatus (Fabricius, 1794) by referring to Barkalov & Gharali (2004), who only reported the species E. tricolor and E. tadzhikorum of the tricolor species group for Iran.
Based on available data on the distribution of the Eumerus tricolor group in Iran, we conclude that the Haftad Qolleh Protected Area (Fig. 1), with eight known species out of a total of 17 Iranian species, holds the most diverse fauna of the group throughout the country. This area, which covers an estimated 97 000 hectares and contains two major valleys, Chekab and Sibak, is located to the east of the provincial capital city of Arak. This mountainous area, with a height of about 3000 m a.s.l. at its summit, has 350 mm of annual precipitation and its temperature varies from -30ºC to 38ºC during the year. Natural springs provide needed water for the wild animals during the dry season. Haftad Qolleh serves as a biodiversity hotspot whose flora comprises at least 641 plant species from 63 families, of which the family Asteraceae with 105 recorded species is the dominant family (Ansari 2017).
Despite that a few species of this group are widely distributed in the West Palaearctic region such as Eumerus tricolor, the available distribution data show that most of the group's species occur in Transcaucasia, Central Asia and the semi-arid to arid areas of Iran. Therefore, we believe that the Eumerus tricolor group fauna in these areas comprises distinctively different species from those of the European and northern African fauna (Peck 1988;Grković et al. 2017Grković et al. , 2019a.
A meticulous examination of the wing vein costa, resulted the observation of a posterodorsal row of long black or light setae basally which extends at least to its half length to crossvein r-m. This character, which appears in all examined Eumerus tricolor group specimens, is here presented for the first time and is included in the diagnosis for this species group.
A male specimen (Figs 4A,7A,19E,21E,23E), collected by Malaise trap from the southeastern city of Khash (Fig. 2), shows striking differences to all other Iranian species in the following combined morphological characters: eyes pilose and dichoptic; face and frons white pilose; ocellar triangle isosceles; basoflagellomere orange; scutum covered with short yellowish pile and with two narrow median pollinose vittae; wing entirely microtrichose; legs predominantly black; protarsus without strong setae posteriorly; abdomen brownish-black. Although it is superficially similar to Eumerus mesasiaticus, it is readily separated from this species by its entirely microtrichose wing, lacking strong setae on the protarsus posteriorly, bare metakatepisternum and simple metafemur (without hump basoventrally). At this point, we have decided to leave this specimen as Eumerus sp. until further sampling from the same locality and relevant type examinations provide sufficient data to determine its identity.