Syritta lyneborgi, Steenis, 2010

Steenis, Jeroen Van, 2010, A new species of the genus Syritta Le Peletier & Serville, 1828 (Diptera, Syrphidae), with new distributional records of other Syritta species, Norwegian Journal of Entomology 57, pp. 111-119 : 112-114

Syritta lyneborgi sp.n.

( FIGS 1–6 )

Type material. Holotype male, Gabon Ogooué- Ivindo rd. Mékambo-Makokou 4 km W Mbela- Baya leg. J.J. Wieringa coll. ZMA.

Etymology: This species is dedicated to the late Leif Lyneborg (Copenhagen) in honour of his major contribution to the knowledge of Syrphidae , especially for the revision of the genus Syritta .

Description. Male. Head ( Fig. 1 ). Face slightly concave, with grey-yellow pollinosity. Oral margin level with frontal prominence. Eye contiguity relatively short, as in S. bulbus . Vertical triangle narrow, widening gradually towards non-pollinose part and from there on widening more sharply, with relatively short pollinose part; ratio between pollinose anterior part and blackish, non-pollinose posterior part 2.0/1.0 (2.0). Colour of pollinosity not visible due to moistening of this part. Distance between eye-margin and anterior ocellus shorter than width of ocellus, as in S. bulbus . Antennae yellow with nearly round basoflagellomere and with yellow-brown arista.

Thorax. Pollinosity on pleurae dark-yellow, ventral part of katepisternum sub shiny. Scutum along anterolateral margin, postpronotum, and postalar callus with dark-yellow pollinosity. Pile predominantly yellow, with a patch of black setae near wing base. Scutellum black with weak and black marginal setae.

Wing ( Figs 4 & 6 ). With strong black veins and a well sclerotised spurious vein, covered by microtrichia.

Legs ( Figs 2–3 ). Front and mid legs yellow, without any modifications. Hind femur yellow in basal part and brown-black in apical part. Hind tarsus yellow, hind tibia brownish with yellow at base and on apical half; with the usual anteroventral carina. Hind femur incrassate, ventrobasal margin straight. Ventrobasal part of hind femur straight without sub basal tubercle, with only five black setula. The last three setula placed close together in one transverse row. Ventroapical part with the usual armature including 4 black posteroventral setae.

Abdomen ( Fig. 5 ). Tergum 1 dark-brown with grey-yellow anterolateral margin. Tergum 2 yellow with black posterior and anterior fascia, anterior fascia not reaching lateral margins. Anterior and posterior fascia connected by a black median vitta. Anterolateral margin yellow pollinose. Tergum 3 yellow with black posterior fascia and dark-brown median vitta from posterior fascia to anterior ⅓ of the tergum. Tergum 4 black with posterior margin dark-yellow. anterolateral margin with rather broad grey pollinose fascia. Sternum 4 with hardly visible V-shaped incision.

Genitalia. Hypandrium (sternite 9) similar to all other Syritta species, with a characteristic apical ctenidion. Epandrium (tergite 9) symetric, broad triangular shaped (in lateral view). Cercus triangular shaped, concave ventrally, with a narrow root. Surstylus divided into a dorsal and aventral lobe, which are clearly separated from each other. Ventral lobe with a long and narrow

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Norwegian Journal of Entomology 57, 111–119 (2010)

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posterior process, anteroventral margin concave, slightly convex at the beginning of the posterior process. Dorsal lobe of surstylus with a basal shaft and a triangular drooping apical part with pilosity on ventromedial and apical part.

Diagnostic characteristics (species group affinity): Wing with a well sclerotised spurious vein, alula microtrichose on posterior half ( S. minuta Lyneborg & Barkemeyer, 2005 entirely microtrichose). Hind tibia simple, with only short pilosity. Scutum with a pollinose vitta only reaching the suture (in the S. tomentosa species-group this vitta reaching the scutellum). Hind femur bicolorous (as in S. rufa Lyneborg & Barkemeyer, 2005 and S. bulbus Walker, 1849 ), without a sub basal bump or tuberculated spina (as in S. minuta and S. breva Lyneborg & Barkemeyer, 2005 ). Tergum 2 with a blackish median vitta (as in S. congoensis Lyneborg & Barkemeyer, 2005 , S. senegalensis Lyneborg & Barkemeyer, 2005 31 Armature of ventrobasal part of hind femur does not include a subbasal ventral structure of substantial size, if such a structure is present it does not differ in size or shape from other structures of the ventrobasal surface. Katepisternum uniformly greyish tomentose............................................................................ 37

- Armature of ventrobasal part of hind femur with a subbasal ventral structure of substantial size ( Figs 7–9, 11 ). [notice absence of such structure in Syritta lyneborgi sp. n., then katepisternum with dense grey-yellow pollinosity on dorsal half, and scattered dark-grey pollinosity on ventral half].......................... 32

32 Subbasal spina of hind femur cone-shaped, arranged in a posteroventral position. Katepisternum uniformly greyish tomentose............................................................... Syritta orientalis Macquart, 1842

- Subbasal structure less well developed, arranged in a true ventral position, or absent........................... 33

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Hind femur bicolorous, yellow-brown in basal part, and brownish-black in apical part...................... 36a

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Hind femur unicolorous, dark-brown to black....................................................................................... 34

36a

All terga orange-yellow, with very restricted blackish pattern. Apical marginal vein and vein R4+5 nearly straight..................................................................... Syritta rufa Lyneborg & Barkemeyer, 2005

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Terga with the usual pattern of yellow and black. Apical marginal vein and vein R4+5 undulated as usual in the genus................................................................................................................................. 36b

Armature of ventrobasal part of hind femur does not include a subbasal ventral structure of substantial size ( Figures 2–3 ). Vertical triangle narrow, widening gradually towards non-pollinose part and from there on widening more sharply, with relatively short pollinose part; ratio between pollinose anterior part and blackish, non-pollinose posterior part 2.0/1.0. Katepisternum with dense grey-yellow pollinosity on dorsal half, and scattered dark-grey pollinosity on ventral half.............................. Syritta lyneborgi sp.n.

- Armature of ventrobasal part of hind femur with a subbasal ventral structure of substantial size ( Figure 11 ). Vertical triangle narrow, widening gradually towards ocellar triangle, with relatively long pollinose part; ratio between pollinose anterior part and blackish, non-pollinose posterior part 4.0-5.0/1.0-2.0. Katepisternum uniformly greyish tomentose................................................ Syritta bulbus Walker, 1849

and S. bulbus ). Vertical triangle narrow, with grey-yellow pollinosity on ventral ⅔. katepisternum with dense grey-yellow pollinosity on dorsal half, and scattered dark-grey pollinosity on ventral half (as in S. vitripennis species-group, and S. hova Lyneborg & Barkemeyer, 2005 ).

The placement as based on the above mentioned characteristics is problematic because of the lack of a sub basal bump or tuberculated spina (not S. bulbus group), and the katepisternum which is partly covered with pollinosity. However the genitalia are similar to those of S. bulbus . On the basis of this similarity S. lyneborgi is placed in the S. bulbus species-group.

Figures

FIGURES 1–6. Syritta lyneborgi sp. n. 1. ♂ Holotype. Head lateral view. 2. ♂ Holotype. hind femur and tibia lateral view. 3. ♂ Holotype. hind femur ventrolateral view. 4. ♂ Holotype. Wing, with microtrichia. 5. ♂ Holotype. Abdomen. 6. ♂ Holotype. Tergum IV, lateral view.

FIGURES 7–11. Hind femur. 7. Syritta congoensis ♂ Paratype DR Congo. Hind femur, lateral view. 8. Syritta rufa ♂ Paratype South Africa. Hind femur, lateral view. 9. Syritta tomentosa ♀ Paratype Cameroon. Hind femur, lateral view. 10. Syritta aenigmatopatria ♂ Indonesia. Hind femur and tibia, lateral view. 11. Syritta bulbus ♂ Ghana. Hind femur and tibia, lateral view.