Perissocerus arabicus Bequaert, 1961

Dikow, T., 2010, Order Diptera, family Mydidae, Arthropod Fauna of the United Arab Emirates 3, Abu Dhabi: Dar Al Ummah, pp. 608-615 : 611-612

Perissocerus arabicus Bequaert, 1961

Specimens examined: Rhas Ganada , 24 ° 45 ' N 54 ° 53 ' E, 1 ♀, 6. xi. 1992, leg. B. Tigar ( BMNH) .

Diagnosis: P. arabicus is a small Mydidae species that is entirely covered with white setae and can therefore be distinguished from other Mydidae in the Arabian Peninsula very easily. The vestigial proboscis and the characteristicshape of the postpedicel in the antennae distinguishes it from species of Rhopalia .

Expanded diagnosis based on specimens studied:

Female. Head distinctly wider than thorax (at postpronotal lobes); interocular distance on vertex greater than at ventral eye margin; vertex not depressed; width of parafacial area (between tentorial pit and median eye margin) about half the width of facial gibbosity (at same level); lateral face, lateral frons, and occiput grey pruinose; facial gibbosity, ocellar triangle, most of frons, and vertex apruinose and black; facial gibbosity distinct, well- developed and distinct in lateral view, entirely covered with long, white mystacal setae; facial gibbosity, frons, vertex, and postgenae with long white setae; occiput with short white setae; proboscis light brown, vestigial, knob-like; maxillary palpi vestigial, light brown with long white setae. Antennae brown; antennae elevated above eye marginin lateral view on distinct protuberance; scape and pedicel with yellow setae dorsally and ventrally, scape more than 2 times as long as pedicel; postpedicel in proximal 1 / 3 cylindrical, distal 2 / 3 bulbous, expanded ventrally,> 3.0 times as long as combined length of scape and pedicel; apical ‘seta-like’ sensory element situated apically in cavity on postpedicel.

Thorax. Brown to black, predominantly apruinose, only antepronotum, katatergite, anatergite, and mesopostnotum grey pruinose; scutum predominantly black, postpronotal lobes and lateral scutum brown. Setation. Distinct notopleural, supra-alar, and postalar macrosetae absent; long, dense, white setae scattered on scutum, postsutural dorsocentral setae directed anteriorly; postpronotal lobes, proepimeron, lateral proepisternum, and anepimeron with long white setae; scutellum brown with white discal scutellar setae. Legs light brown with white setae; coxae partly brown, apruinose; femora brown, met femora only slightly expanded distally, no ventral macrosetae; pro and mes tibiae laterally arched, met tibia straight, met tibia without ventral keel; pro and mes proximaltarsomeres as long as 2 nd tarsomere, met proximal tarsomere longer than 2 nd tarsomere; pulvilli reduced, vestigial, less than 1 / 4 of length of well-developed claws, only as wideas base of claws. Wings. Length 8.2 mm; hyaline throughout, very few microtrichia scattered on wing, veins light brown, R 2, R 4, R 5, and M 1 + 2 predominantly white, marginal wing cells closed except for cells r 4 and r 5 which are open; C terminating at junction with R 5; R 4 terminating in R 1; R 5 terminating in C; stump vein (R 3) absent at base of R 4; R 4 and R 5 (forming cell r 4) more or less parallel to each other, not particularly constricting cell; M 1 + 2 terminating in C; CuA 1 and CuA 2 split proximally to m-cu (cell m 3 narrow proximally); alula well-developed, but not touching scutellum medially; haltere light yellow.

Abdomen. Predominantly brown, T 2 as wide as T 1, T and S apruinose, T 1 with long white setae throughout, T 2 - 4 with long white setae laterally; T 2 - 7 with posterior margin yellow; bullae on T 2 brown and transversely elongate; S brown with white setae. Genitalia. Ovipositor with acanthophorite plates each with 9 spurs; internal structures not studied. Due to the preservation of the specimen the exact shape of the postpedicel can not be determined.

Remarks: This species was described by Bequaert (1961: 33) from Al Huseini (near Lahy = Lahij, 13 ° 03 ' N 44 ° 53 ' E) in south-western Yemen and is here recorded for the first time from the UAE. The holotype is deposited in the BMNH. An image of a male specimen from Dubailand, Dubai, UAE (24 ˚ 59 ' N 55 ˚ 19 ' E, 2. x. 2006, D. Gardner) has been published in Howarth (2006: Fig. 3).

Distribution: Yemen, UAE.