Chamaemyia xanthopoda, Ebejer, M. J., 2017

Ebejer, M. J., 2017, A conspectus of the silver-flies (Diptera: Chamaemyiidae) of the Middle East with descriptions of new species of Chamaemyia Meigen and Melanochthiphila Frey, from the Arabian Peninsula, Zootaxa 4319 (3), pp. 461-482 : 468-472

Chamaemyia xanthopoda sp. n.

( Figs 15–22 )

Diagnosis. An easily recognized pale grey pollinose species which has the whole antenna, all legs including anterior and middle coxae and all femora, as well as the epandrium yellow; wing with dark veins especially costa and at apex of R and M veins and dark infuscation around crossveins and at apex of R2+3.

Description. Male. Head: ( Figs 17, 18 ) as long as high, greyish brown pollinose, but orbits along eye margin and gena paler; face slightly higher than broad; lunule pollinose as frons and at middle about as long as pedicel; eye elongate, length to height 1.4:1; gena at narrowest part as high as 0.8 height of first flagellomere; occiput greyish yellow pollinose as scutum; 2 long orbitals, each about 3/4 length of frons, long proclinate ocellars arising in line with anterior ocellus and reaching anterior margin of frons, medial and lateral verticals as long as orbitals, postverticals strong; a few very short setulae scattered across anterior half of frons mainly around anterior orbital; all setae and setulae black; antenna completely yellow with only a faint pale brown infuscation near tip and on external surface of first flagellomere; arista pale brownish yellow with paler yellow second segment and distinctly pubescent; pedicel with one long black seta dorsally and three very long black setae ventrally, these reaching beyond middle of first flagellomere; gena with an irregular row of long black setae along middle; proboscis and palp pale yellow.

Thorax: ( Fig. 16 ) completely pale greyish brown pollinose with a distinct golden sheen from various angles of illumination, most noticeable on posterior half of scutum, notopleuron and posterior half of anepisternum; scutum with darker brown vitta on each side below dorsocentral lines running from middle dorsocentral to hind margin of scutum; prescutellum present but very narrow; pleura with dense grey pollinosity; chaetotaxy: 1 postpronotal, 2 notopleurals, 1+2 dorsocentrals, 1 presutural, 1 supra-alar, 1 post-alar, acrostichals in four rows anteriorly, becoming 2 posterior to middle dorsocentral, prescutellars though distinct and short are twice as long as other acrostichals, 2 pairs of scutellars, 1 strong and 1 weak katepisternal just behind middle of superior margin; all setae apart from acrostichals very long; legs entirely pale yellow, only posterior coxa grey at base and hind femur weakly greyish pollinose on middle third antero-ventrally; fore femur with posteroventral row of long setae; all setae and setulae of legs black; hind femur distinctly thickened—about 2 times thickness of tibia; wing ( Fig. 19 ) hyaline with a faint brown tinge especially along costa in apical half; distinct dark brown infuscation present around crossveins and apex of R2+3; veins dark brown apart from pale yellow R1 and costa from base to apex of R1 and stem veins; squama and halter pale yellow, knob of halter dorsally with brown spot.

Abdomen: pale greyish brown pollinose as thorax with two pairs of small black spots on each tergite 3–5, fairly densely scattered black setulae on all tergites those along posterior margin longer, about half as long as tergite.

Postabdomen: epandrium ( Fig. 15 ) large and yellow; hypandrium broad basally and invaginated prior to origin of pregonite, thus in lateral view ( Fig. 20 ) there appears a “fold” between it and the phallapodeme; postgonite ( Figs 20, 22b ) broad and angled away from midline at its base; pregonite narrow just before apex where two setulae arise; aedeagus of very characteristic shape in lateral view ( Fig. 22c ) being markedly angled at middle.

Average length male and female: body 3.2 mm, wing 3.3 mm.

Female: similar to male in all respects of pollinosity and colouration but lateral spots on tergites larger and tergite 7 mainly yellow.

Variation: first flagellomere varies from clear yellow to pale brownish yellow especially on lateral aspect; hind femur at middle may have a small area anterior-ventrally pale grey and pale grey pollinose, rarely this extends over almost whole length of femur, but the overwhelming appearance is that of pale colouration; the intensity of the wing infuscation varies but the basic pattern remains.

Etymology. The name is from the Greek words xanthos —yellow and podi —leg, and refers to the yellow colouration of the legs.

Material examined. holotype, ♂, Saudi Arabia: Asir, Abha, Hay Al-Nusub , vegetable farm, 1–25.v.2013, Malaise trap, HAD ( NMWC) . Paratypes: 1♂ 2♀, same data and depository ; 1♂ 1♀ same data ( CSCA) ; 1♂ 2♀, Asir, Abha, Al-Souda, Bani Mazen , 25.ii–1.v.2013, Malaise Trap, HAD ( CERS-JU) ; 1♂ 1♀, Asir, Abha , Al- Souda, Al-Muktatha dam, 14.iii.2013, HAD ( NMWC) ; 2♂ 2♀, Asir, Abha, Hay Al-Nusub , vegetable farm, 20.iv.2013, Malaise trap, HAD (MJE) ; 2♀, Asir, Abha, Hay Al-Nusub , 18°13ʹN 42°30ʹE, 19.vi–9.vii.2013, Malaise trap, HAD ( CERS-JU) ; 2♂, Asir, Abha, Hay Al-Nusub , 18°13ʹN 42°30ʹE, 3–24.vii.2013, Malaise trap, HAD ( NMWC) ; 1♂ 1♀, Asir, Abha, Hay Al-Nusub , 18°13ʹN 42°30ʹE, 6–27.vii.2013, Malaise trap, HAD ( BMNH) ; 1♀, Asir, Abha, Hay Al-Nusub , 18°13ʹN 42°30ʹE, 9–30.v.2014, Malaise trap, HAD ( CERS-JU) ; 1♀, Asir, Abha, Al-Souda, Al-Muktatha dam, 31.xii.2014, HAD ( BMNH) .

Distribution. Saudi Arabia.

Similar species: the yellow antenna would place this species close to the C. flavipalpis (Haliday, 1838) group of Palaearctic species, but none of these have a yellow epandrium and yellow femora. The dusky brown costal margin would place this species near C. fumida Tanasijtshuk, 1986 which has black femora and a more intense infuscation along the entire length of the costa, but not a yellow epandrium. Thomson (1869) described Chamaemyia sexnotata from the Cape of Good Hope, South Africa, a species with yellow femora and coxae (although having examined more specimens, I note that this is not a consistent feature; some specimens do have pale greyish rather than entirely yellow femora, see Figs 27, 28 ), as well as dark wing veins and costal infuscation. Although his description was quite detailed he could make no mention of the colour of the epandrium, the type being a female. It is difficult to assess the intensity or otherwise of the wing markings without examination of specimens. At my request, Ingve Brodin (Swedish Museum of Natural History, Stockholm) kindly sent photographs ( Figs 23–26 ) of the holotype registration number: NHRS-BYWS2309. Also, through the kindness of Tricia Pillay (KwaZulu-Natal Museum, Pietermaritzburg, South Africa), I received a number of photographs ( Figs 27–29 ) of specimens in their collections that were identified as C. sexnotata Thomson , by B.H. Cogan (Natural History Museum, London) in 1985 when he had Thomson’s type in front of him. Although the provenance of the material he saw included localities in Zimbabwe and South Africa (Natal, Drakensberg Mountains and Oribi Gorge) and these sites are a distance from the Cape of Good Hope and at some altitude, I see no reason to disagree with Cogan’s opinion that the specimens in the collections in Natal and London are C. sexnotata . Chamaemyia xanthopoda and C. sexnotata are quite different species. The most significant differences between them are a much more intense infuscation of the costa extending right around the apex, darker and broader dorsocentral vittae that extend on to the scutellum, more frequently greyish femora and a large black epandrium in C. s exnotata. Both species have the ventral half of the epandrium broader than the dorsal half compared to Palaearctic species.

Figures

FIGURES 15 – 19. Chamaemyia xanthopoda sp. n. paratype, 15) habitus left lateral view, 16) scutum, dorsal view, 17) head, left lateral view, 18) frons, dorsal view, 19) right wing.

FIGURES 20 – 22. Chamaemyia xanthopoda sp. n. paratype, 20) male postabdomen right lateral view, 21) same, ventral view, 22) gonites and aedeagus: a, right gonites ventral view b, same right lateral view, c, aedeagus right lateral view, d, same ventral view. Abbreviations as in Figs 5, 6. Scale bars = 0.2 mm.

FIGURES 27 – 29. Chamaemyia sexnotata (Thomson). 27) male habitus, left lateral view, 28) female habitus, ventro-lateral view, 29) male postabdomen in situ, left lateral view.

FIGURES 23 – 26. Chamaemyia sexnotata (Thomson) holotype female, 23) habitus oblique left lateral view, including wing, 24) specimen labels, Cap. B. Sp. = Cape of Good Hope and Kinb. = Johan Kinberg, the collector, 25) left lateral view, 26) dorsal view.