Aphaniosoma frequens, Ebejer, 2009

Ebejer, Martin J., 2009, A revision of Afrotropical Chyromyidae (excluding Gymnochiromyia Hendel) (Diptera: Schizophora), with the recognition of two subfamilies and the description of new genera, African Invertebrates 50 (2), pp. 321-321 : 397-400

Aphaniosoma frequens sp. n.

Figs 43 , 44

Etymology: From Latin frequens (frequent), denoting its common and widespread occurrence in the samples taken in Africa.

Diagnosis: Dark grey species with yellow fr and antennae, pleural sutures narrowly bordered with yellow, tarsomere 5 of all legs brown and male postabdomen with large, dark, broad psg, beaked at tip most often easily visible without dissection, prg st of unusual shape with midline process at apex and distiph with long divergent lobes.

Description:

Male.

Head: Yellow, ocp dark grey except for narrow yellow postocular border, oc triangle dark grey, fr broad but converging anteriorly so that at level of antennae it is about 0.6 as wide as at level of anterior oc, face small, depressed and with distinct, narrow but low facial carina, eye oval lying oblique, gena yellow, at middle about 0.6 height of eye and having numerous pale setulae, 2 short setae at vibrissal corner, mouthparts small, yellow, 6 setulae scattered on fr with 2 pairs of longer setulae in front of oc triangle, 4 orb getting progressively shorter from back to front, 1 vti and 1 vte, pvt distinct and convergent, oc long, divergent, antenna yellow, most of second segment of arista dark. Thorax: Scutum, scut and mtn entirely dark grey, pprn and ntpl yellow, pleura mostly dark grey, but for narrow yellow margins to sutures. Chaetotaxy: 1 pprn, 1 posthu, 1 ihu, 2 ntpl, 0+2 ia, 2+5 acrs, 2+4 dc only the posterior two well-developed, prpl distinct, 1 pa, 2 pairs of marginal scut, 1 katepisternal with shorter seta in front and several setulae on anterior part of sclerite, 1 anepisternal, all setae pale yellow to pale brown. Wing: Hyaline and uniformly microtrichose, veins pale brown, distance between R 2+3 to R 4+5 on costal margin about 0.5 that between R 4+5 and M 1+2, distance between crossveins about 1.3× length of posterior crossvein and length of apical section of Cu about 2.6× length of posterior crossvein. Haltere pale yellow.

Legs: Yellow and fine yellow setulose, tarsomere 5 of all legs brown.

Abdomen: Almost entirely dark brown, only the narrowly visible membrane between segments pale. Postabdomen: No distinguishing external features.

Female.

As male, but some specimens have a yellow longitudinal midline stripe on tg 6 & 7 (not a diagnostic feature as it is present in many species) as a result of partial desclerotization. Postabdomen: tg 8 closely attached to cerc, hypr large, but membraneous; st 8 thinly sclerotized with middle section showing two very small tubercles with a microtrichium on each.

Length: ơ and ^body 0.9 mm, wing 1.1 mm.

Variation:A few specimens are of a lighter grey on the thorax and those from St Helena have a pale scut.

Holotype: ơ NAMIBIA: Skeleton Coast Park , Kunene R. mouth, 17°15'97"S:11°46'83"E, sweeping marginal grasses and reeds on flood plain, 17–18.iii.1998, A.H. Kirk-Spriggs ( NMNW).

Paratypes: NAMIBIA: 7ơ 4^same data as holotype ( NMNW) ; 2ơ 2^nr Onseepkans , Orange R. banks, 8–10.i.1972, Southern African Expedition (W0) B.M. 1972–1 ( BMNH) ; 86ơ 9^Otjitambi farm, 47 km ESE Kamanjab, 13–15.ii.1972, Southern African Expedition (W37) BM 1972–1 ( BMNH) ; 7ơ 6^nr Onseepkans , Orange R. banks, 8–10.i.1972, Southern African Expedition (W1) B.M. 1972–1 ( BMNH) ; 6ơ 2^Kuiseb R. canyon, 22–23.i.1972, riverside vegetation, Southern African Expedition (W22) B.M. 1972–1 ( BMNH) ; 1^Khorixas District , Gai-As spring, 20°46'01"S: 14°01'12"E, 22.x.1998, A.H. Kirk-Spriggs & E. Marais ( NMNW) ; 1ơ 3^Khorixas District , Huab R. at Krone 721, 20°37'09"S: 13°54'31"E, sweeping grasses and sedges, 23–26.x.1998, A.H. Kirk-Spriggs ( NMNW) ; 1ơ 1^Brandberg , Messum valley, alt. 700 m, 21°13'29"S:14°30'98"E, 3.iv.1999, S. van Noort & S.G. Compton, UV-light trap in sparsely vegetated river valley, Bushy-Karoo-Namib shrubland (in alcohol, NMWC) ; 11ơ 4^Windhoek District , Greylingshof 107, Gaub Canyon, 23°29'S: 16°48'E, 2–3.x.1999, Malaise trap, A.H. Kirk-Spriggs & T. Pape ( NMNW) . KENYA: 1ơ Hunter’s Lodge nr Kiboko, 02°14'S: 37°43'E, 8–9.viii.2003, A. Freidberg ( TAUI) ; 1ơ Simba , NBI-MSA rd, 02°09'S: 37°34'E, 23.viii.2003, A. Freidberg ( TAUI) ; 1ơ 3^Hunter’s Lodge , 02°13'S: 37°43'E, 13–16.ix.2005, A. Freidberg ( TAUI) . ST HELENA ISLAND: 1^Sandy Bay , 17.ii.1962, A. Loveridge ( BMNH) ; 2ơ 4^St Helena Island, 1963, A. Loveridge; all specimens are glued on a card on the same mount, one has been removed and macerated, and is preserved in a glycerine vial on the same pin (BMNH).

Remarks. The specimens from St Helena bear the identification label “ Aphaniosoma approximatum, Becker , det. J.C. Deeming 1963”. The identification was based on a dissected male and the available literature at the time. I re-examined this specimen, which, although a little faded, remains in good condition and the postabdomen matches that of frequens and not that of approximatum . There are minor differences in the hypopygial structures of the species from St Helena: the psg is very slightly broader, the lower edge of tg 6 is more pointed where this projects laterally from the plane of the tg, the distal end of the basiph is notched in both, but in the St Helena specimens it is slightly deeper. I do not consider these to be anything more than minor variations and,

given the highly characteristic pregenital st and distiph being the same in both series, I consider the St Helena specimens merely a variation of frequens and not a sibling species or a subspecies.

Figures

Fig. 43. Aphaniosoma frequens sp. n., ơ: (a) psg, posterior; (b) hypopygium, lateral; (c) st 6, ventral; (d, e) distiph, lateral (d) and ventral (e). Scale bars = 0.2 mm.

Fig. 44. Aphaniosoma frequens sp. n., ^postabdomen: (a) posterior, (b) lateral, (c) spermathecae. Scale bar = 0.15 mm.