Ocypodomyia stuckenbergi, Pont, 2006

Pont, Adrian C., 2006, Ocypodomyia gen. n. from the seashores of the Afrotropical region (Diptera: Muscidae: Limnophorini), African Invertebrates 47, pp. 321-334 : 326-329

Ocypodomyia stuckenbergi sp. n.

Figs 1 , 3–5 , 7, 8 , 10–16

Etymology: The species is named after its collector, the eminent South African dipterist Brian R. Stuckenberg.

Description:

Male.

Head: Ground-colour black. Eyes bare. Entire head except for eyes and antennae silverywhite pruinose. Frons short and very broad, at lunula 0.6 of head-width at this point ( Fig. 1 ), broadening slightly from vertex to lunula. Ocellar setae very short; inner and outer verticals short, the outer 2/3 as long as the inner and equal to an ocellar seta in length. Post-ocular setulae in a single row. Frons uniform in appearance, with a differentiation into fronto-orbital plates, frontal vitta and ocellar triangle almost undetectable. 2–5 pairs of very short proclinate frontal setulae on lower 2/3 of frons, these sometimes minute and scarcely detectable, and above them with 2 pairs of equally short proclinate orbital setulae, these all usually arranged irregularly. Profrons very high, so that the face and antennae are unusually long ( Fig. 10 ), the distance from profrons to ocellar seta equal to half the distance from profrons to vibrissa. Antennae black, the apical part of pedicel orange, the flagellomere with grey pruinosity visible from some angles. Flagellomere very long, in lateral view reaching almost to level of vibrissa. Arista mainly orange, bare. Parafacial broad, at narrowest point almost as wide as width of flagellomere. Face narrow and very sunken, with a sharp vertical carina along its length, and lower anterior part of head much enlarged as a result. Lower facial margin narrow, the vibrissae unusually close together ( Fig. 11 ). Facial ridges bare. Vibrissae strong, crossed. Gena broad, below lowest eye-margin equal to half depth of an eye; bare except for a row of setae along lower margin. Proboscis short, slender, the prementum glossy dark brown. Palpus orange to brown, slender.

Thorax: Ground-colour black. Wholly whitish, almost silvery-white dusted, without dark vittae or spots anywhere on scutum, scutellum or pleura. Spiracles white.All setae short. Acrostichal setulae 2-serial at first, 3- to 4-serial at suture, with a very weak prescutellar pair of setae; 2+3 dorsocentrals; 1+2 intra-alars; postsutural setae weak; 1+1 supra-alars; 2 postpronotals; prealar absent; 2 postalars. Prosternum, proepisternal depression and anepimeron bare. Notopleuron with 2 setae, otherwise bare. Proepisternum and proepimeron each with 1 seta and 1 setula, all directed upwards. Anepisternum with 4 setae in posterior row, and a strong setula in upper anterior corner; 1+2 katepisternals, the lower one much shorter than the upper two and closer to upper posterior than to upper anterior seta. Meron with 2–4 short setulae below spiracle. Posterior spiracle without setulae on margin. Katatergite pilose. Anatergite bare. Scutellum with 1 pair of sub-basal lateral and 1 pair of apical setae; disc with 13–20 setulae; lateral margins and ventral surface bare.

Legs: Coxae dark; trochanters orange; femora narrowly orange-yellow at base and at tip, otherwise dark and grey dusted; tibiae and tarsi orange-yellow, some partial darkening in apical part of tibiae. Without modifications in structure or setation. Fore femur with a posteroventral row, the setae weaker in basal half. Fore tibia with a short submedian posterior seta, absent in most of the Aldabra specimens; 1 dorsal and 1 short posteroventral apical setae. Mid femur without ventral setae; with a submedian anterior seta; 0 anterior and 2, rarely 1, posterior preapical setae. Mid tibia with 2 posterior setae, without anterodorsals or ventrals. Hind femur with 2–4 anteroventral setae in apical half, otherwise only with setulae on this surface; posteroventral surface with rather longer setulae in basal half; with an anterodorsal row, the setae becoming more dorsal towards apex; 1 dorsal and 0 posterodorsal preapical seta. Hind tibia with 1 anterodorsal and 1, rarely 2, anteroventral seta(e), without posterodorsal; 1 dorsal but no anterodorsal preapical seta; 1 anteroventral but no posteroventral apical seta. Hind tarsomere 1 with a short ventral setula near base.

Wing: Clear, the surface entirely covered with microtrichia and appearing rather milky. Basicosta and tegula yellow. Veins yellow. Costa continuing round wingtip to the apex of vein M, the costal spine tiny. Veins bare except for costa. Subcosta running in a somewhat sinuous course from humeral cross-vein to costa, not in a smooth curve. Cross-vein r–m below or slightly beyond the point where vein R 1 enters costa. Cross-vein dm–cu upright, straight. Vein M running straight to wingmargin, not inclined forwards. Vein A 1 extending over halfway from its base to wing-margin. Calypters white, including margins. Lower calypter of the Phaonia - type and projecting well beyond upper one. Haltere with the stem orange and the knob pale yellow.

Abdomen: Ground-colour black. Dorsal surface wholly white, almost silvery-white dusted, without any dark markings. Tergites without setae, except for tergite 5 which has 2 or 3 pairs of lateral discals and a row of marginals. Ventral part of tergites and sternites whitish dusted. Sternite 1 narrow, with a short fine setula on each side, sometimes with several. Sternite 5 with the lobes broad, pale ( Fig. 14 ).

Genitalia: Cercal plate deeply cleft dorsally and ventrally ( Fig. 15 ). Surstyli simple ( Fig. 16 ). Hypandrium with a pair of large rounded bulbous prolongations ventrally. Phallapodeme and epiphallus well developed. Praegonite large, spade-like; postgonite curved, without setulae. Aedeagus long and slender, the tip membraneous, without trace of any armature.

Measurements: Length of body, 2.8–3.3 mm. Length of wing, 2.3–2.8 mm.

Female.

Differs from the male as follows:

Head ( Figs 12, 13 ): Proportions slightly different, and the setulae rather stronger and more numerous. Frons at lunula also 0.6 of head-width at this point. Ocellar and vertical setae longer and stronger. 2 or 3 pairs of short proclinate frontals, and above them with 2 pairs of orbitals, the lower one proclinate, the upper one directed backwards and usually outwards, and outside them on the fronto-orbital plate with a few (rarely 6 or 8) short proclinate setulae. Profrons not so high and therefore less angular, the distance from profrons to ocellar tubercle 0.7 the distance from profrons to vibrissa. Antennal flagellomere (and face) much shorter, 2.5 times as long as wide. Parafacial broader, slightly wider than width of flagellomere. Lower anterior part of head not so enlarged, and mouth-margin reaching forwards beyond level of profrons in profile. Gena rather narrower, below lowest eye-margin equal to only 0.3 of the depth of the eye.

Thorax: Rarely up to 23 discal setulae on scutellum.

Legs: Hind femur with only 1 or 2 anteroventral setae, and the posteroventral setulae not developed.

Abdomen: Tergite 5 with the marginal setae weak, only 2 pairs.

Ovipositor ( Figs 7, 8 ): Very fragile and difficult to dissect. Tergite 6 as two broad plates; sternite 6 as a narrow median rod. Tergite 7 as a pair of strongly sclerotised rods, each with a pair of small platelets at tip; sternite 7 absent, represented by a pair of bristledots. Tergite 8 as a pair of bars running down the side of the ovipositor; sternite 8 as a pair of small hind-marginal platelets. Membrane between segments 7 and 8 with tiny spicules. Epiproct, hypoproct and cerci setose, without spines. 3 spherical spermathecae. Measurements: Length of body, 3.7–4.5 mm. Length of wing, 2.8–3.4 mm.

Holotype: ơ MADAGASCAR: Tuléar : Fort-Dauphin, Sainte-Luce, alt. 10 m, 22–24.ii.1958, B. Stuckenberg ( NMSA).

Paratypes: MADAGASCAR: Tuléar: same locality data as holotype, 3ơ 5^(2ơ 4^NMSA, 1ơ 1^BMNH); Saint-Augustin , alt. 6 m, 11–13.ii.1958, B. Stuckenberg, 1ơ ( NMSA) ; Antananarivo: Ankazobe,

Ambohitantely , alt. 1600 m, 4–9.xii.1957, B. Stuckenberg, 1ơ ( NMSA) ; Toamasina : Fenerive, lagoon shore, xii.1955, B. Stuckenberg, 4ơ 1^(3ơ 1^NMSA, 1ơ BMNH) . SEYCHELLES: Aldabra : Picard, Gigi, 19– 20.iii.1986, W.N. Mathis, 2ơ 6^(1ơ 4^USNM, 1ơ 2^BMNH) ; Picard , Gigi, 24.iii.1986, W.N. Mathis, 1ơ ( USNM) ; Cosmoledo : Menai I., station, 26.iii.1986, W.N. Mathis, 1^( USNM) .

Discussion: The abdomen of one macerated female contained some 14 complete eggs together with the remnants of several others. The egg is white, simple, boat-shaped, with a pair of dorsal pleats, without any projections or ornamentations at the tips.

Distribution: Known only from Madagascar and the Indian Ocean islands of Aldabra and Cosmoledo.

Figures

Figs 1, 2. Male frons, dorsal view: (1) Ocypodomyia stuckenbergi sp. n. (Madagascar, Sainte-Luce); (2) Ocypodomyia africana sp. n. (Angola, Cuanza R.). Scale bar = 1 mm.

Figs 3–6. Male genitalia of species of Ocypodomyia gen. n.: (3–5) O. stuckenbergi sp. n. (Madagascar, Ambohitantely): (3) aedeagus, lateral view, (4) hypandrium, anterior view, (5) aedeagus, ventral view; (6) O. africana sp. n. (Senegal, Plage Somone), aedeagus, lateral view. Abbreviations: a – praegonite, b – postgonite, c – phallapodeme, d – epiphallus, e – distiphallus, h – hypandrium, hp – paired hypandrial prolongations. Scale bar = 0.5 mm.

Figs 7–9. Ovipositors of species of Ocypodomyia gen. n.: (7, 8) O. stuckenbergi sp. n. (Madagascar, Sainte- Luce): (7) dorsal view, (8) ventral view, sternite 8; (9) O. africana sp. n. (Angola, Cuanza R.), ventral view, sternites 6, 7. Abbreviations: tg – tergite, st – sternite. Scale bar = 1 mm.

Figs 10, 11. Male head of Ocypodomyia stuckenbergi sp. n. (Madagascar, Sainte-Luce): (10) head, lateral view; (11) face, frontal view. Scale bar = 1 mm.

Figs 12, 13. Female head of Ocypodomyia stuckenbergi sp. n. (Madagascar, Sainte-Luce): (12) head, lateral view; (13) frons, dorsal view. Scale bar = 1 mm.

Figs 14–16. Male genitalia of Ocypodomyia stuckenbergi sp. n. (Madagascar, Ambohitantely): (14) sternite 5, dorsal view; (15) hypopygium, dorsal view; (16) hypopygium, lateral view. Scale bar = 1 mm.