Eremomidas arabicus Bequaert 1961

E. arabicus is distinguished from other Eremomidas species by the overall white or light grey appearance , the sharply depressed vertex, the absence of long setae on thorax and abdomen, the vestigial proboscis, and M1+2 terminating in R1. To this day, it is the largest species of Mydidae found in the Arabian Peninsula, with females having a wing length of 17.5–18.2 mm. Source: Dikow, T. (2010): Order Diptera, Family Mydidae. Arthropod fauna of the UAE, 3: 608–615

Male. Head distinctly wider than thorax (at postpronotal lobes); interocular distance on vertex smaller than at ventral eye margin; vertex sharply depressed (nearly 90˚ angle on median eye margin); width of parafacial area (between tentorial pit and median eye margin) less than half the width of facial gibbosity (at same level); densely white pruinose, only ocellar triangle, vertex, and postgenae apruinose and dark brown; facial gibbosity distinct, discernible in lateral view, entirely covered with long, white mystacal setae; frons, vertex, and occiput with white setae; proboscis light brown, vestigial, knob-like; maxillary palpi laterally compressed, light brown, slightly longer than proboscis. Antennae brown; scape and pedicel with white setae dorsally and ventrally, scape longer than pedicel; postpedicel in proximal half cylindrical, distal half symmetrically bulbous, >2.0 times as long as combined length of scape and pedicel; apical ‘seta-like’ sensory element situated apically in cavity on postpedicel. Thorax. Light brown, predominantly white pruinose, only postpronotal lobes, proepisternum, anterior half of anepimeron, and posterior half of scutellum apruinose; scutum with faint dark grey longitudinal stripes just lateral of median line and laterally with presutural and postsutural spots. Setation. Distinct notopleural, supra-alar, and postalar macrosetae absent; white setae scattered on scutum, but not on faint dark grey spots/stripes, longest laterally dorsal to anepisternum; antepronotum, proepisternum, and postpronotal lobes with long white setae; katatergite and apruinose part of anepimeron with short white setae; scutellum, mesopostnotum, and anatergite asetose. Legs light brown to brown with white setae; pro and mes coxae apruinose, met coxae white pruinose; femora brown, met femora cylindrical as wide as pro and mes femora, met femora without ventral macrosetae; pro and mes tibiae laterally arched, met tibia straight, met tibia without ventral keel; pro and mes tarsomeres of equal length, met proximal tarsomere as long as combined length of 2nd and 3rd tarsomeres; pulvilli well-developed, as long as well-developed claws, much wider than base of claws. Wings. Length 11.2–11.4 mm; hyaline throughout, very few microtrichia scattered on wing, all veins light yellow, all marginal wing cells closed; C terminating at junction with R1; R4 either terminating in R2+3 or R1; R5 terminating in R1; stump vein (R3) present at base of R4; R4and R5(forming cell r4) more or less parallel medially; M1+2 terminating in R1; CuA1 and CuA2split proximally to m-cu (cell m3narrow proximally); alula very large, touching scutellum medially; haltere light yellow. Abdomen. Predominantly brown, T2 as wide as T1, T white pruinose, S predominantly apruinose, scattered white setae; T1–7 well-developed and visible; T2 with anterior apruinose stripe; T1–6 posterior margin yellow; bullae on T2 light brown and circular; S1 entirely yellow, S2–7 posterior margin yellow. Terminalia not studied in detail. Female. Interocular distance on vertex nearly as wide as width of base of scutellum (nearly 3 times as wide as in male) width of parafacial area (between tentorial pit and median eye margin) more than half the width of facial gibbosity; head setation much shorter, only few mystacal setae; thoracic setation much shorter; pulvilli on all tarsi about half the length of claws, only as wide as base of claws; wing length 17.5–18.2 mm; abdominal pruinosity reduced, only T1 completely white pruinose, T2–3 (slightly on T4) only laterally pruinose, T5–8 entirely apruinose; tergites proximally brown in varying extent. Genitalia. Ovipositor with acanthophorite plates each with 7 spurs; internal structures not studied.

Distribution: Yemen, Oman, UAE. This species is therefore distributed in both the Afrotropical and Palaearctic regions. For the most accurate distribution records of this species see Torsten Dikow's research site.

The genus Eremomidas contains five species, one of which is found in Arabia (Dikow, 2010). Eremomidas arabicus was only recently recorded to occur in the United Arab Emirates (UAE), however, specimens had been collected and stored in the Joint Al Ain and Abu Dhabi Insect Collection of the Emirates Natural History Group (JAAENHG) for more than 20 years (Howarth & Gillett, 2009) before being formally identified by Torsten Dikow in 2010. In fact, when Dikow was pulling together a chapter for Volume 3, Arthropod Fauna of the United Arab Emirates (edited by Tony van Harten), Brigitte Howarth (curator and custodian of the JAAENHG) sent a specimen from the collection to him. This specimen represented the earliest record of the presence of this species from the UAE, collected in 1979 by the founder of the ENHG, Bish Brown. In 2010 Brigitte Howarth photographed E. arabicus in sand dunes on the outskirts of Al Ain, United Arab Emirates. The individual depicted in the photographs is a gravid female, looking for a suitable ovipositing site. Little is known about the habitat niche of this fly but the observations of egg laying indicate that the egg, larval and pupal stage are spent in the sand, before emerging as an adult. In the United States, a mydas fly commonly called the 'Delhi Sands flower-loving fly' (Rhaphiomidas terminatus abdominalis) a species of Mydidae known to occur in ancient sand dune systems bordering on extinction was given conservation status 'endangered' in 1993 (US Fish and Wildlife Publication, 1993) due to the destruction of 97% of its habitat range. In 1997 a recovery plan was published to ensure its return from the brink of extinction (US Fish and Wildlife Publication, 1997). E. arabicus has been found in ancient dune systems in the UAE and these are rapidly being lost to development. Much like the Delhi Sands flower-loving fly, E. arabicus could be an indicator species for ancient sand dune systems, and much like its American counterpart, it may very well be highly endangered.