Paragus yerburiensis, Stuckenberg, 1954

Stuckenberg, B. R., 1954, The Paragus Serratus Complex, With Descriptions Of New Species (Diptera: Syrphidae), Trans. R. Ent. Soc. Lond 105 (17), pp. 393-422 : 415-418

Paragus yerburiensis sp. n.

This species has a transverse band of black across most of the first abdominal segment. The posterior corners of the abdomen are very much produced, and the abdomen appears to be truncated in the males. The epandrium is elongated, the inferior claspers are greatly enlarged, and the superior claspers are borne on long narrow processes.

Male.-Head: Face dark yellow, with distinct punctures and a silvery-white pile. No median stripe, facial tubercle brown. Oral tubercle piceous, and surrounded by a dark brown strip. Two basal segmenb of antennae very dark brown, second segment suffused with black above. Third segment elongated and cylindrical, crineous above and tawny on lower surface at base, twice as long as first two together. Vertex fusco-piceous with dull violaceous reflections; tomentum of occiput extends for a short distance past upper corners of compound eyes, closing the vertax from behind. Stripes of hair on eyes distinct and quite heavy, outermost on each eye the widest, and broadly interrupted in the middle. Thorax: Mesonotum rather dull black, with pale violaceous reflections; quite heavily punctate. Mesonotal pile short and yellowish. Mesonotal stripes heavy and conspicuous, yellowish in front and grey behind, each broad, and meeting in region of transverse suture. Scutellum dark fusco-piceous on basal half, dark yellow on remainder. Sixteen long scutellar teeth, each tipped with black. Legs: Posterior femora with a very dark brown band on their median half, basal quarter testsceous, and apical quarter creamy-yellow. Posterior tibiae yellowish on basal half, ferrugino-testaceous with a dark median band on remainder. Whole tarsus missing from left posterior leg, and two apical segments missing on right leg, remaining three segments red-brown with a grey suffusion. The two anterior pairs of femora testaceous on basal two-thirds, pale yellow on the rest. The two anterior pairs of tibiae pale yellow on a little more than basal half, pale testaceous on remainder and on tarsi. Wings: Narrower than in the other species. Membrane hyaline and a little glossy. Stigma pale yellow, and veins very dark brown, almost black, and rather thin. Microtrichia on membrane sparse. Subcosta and apical part of first longitudinal vein brown. Abdomen (fig. 28): First segment piceous across more than its anterior half, this dark colour extending diagonally across each side of seoond segment, ending at apical cornem of that segment. Second segment with a median, fusco-piceous, triangular patoh. Third segment entirely fusco-piceous behind first pair of vittae, this colour extending forward between vittae, stopping at margin of second segment in alignment with the triangular patch mentioned above. Remainder of first three segments yellow-brown. Fourth segment fusco-piceous and fifth segment similar. Anterior margin of each anterior vitta inconspicuous against the paler colour of third segment, but posterior margin distinct against dark colour of that segment. Middle and posterior pairs of Vittae distinct, and a little creamy. Abdomen of a characteristic shape. Sides almost parallel, diverging a little anteriorly, each curving gently backwards from moderately prominent shoulders. Second segment subtriangular in cross-section, third segment decidedly more rounded; sides of posterior part of fourth segment vertical, a little curved above. Posterior corners of abdomen markedly produced and broadly rounded and swollen, giving the abdomen a rather truncated appearance. Margins of abdomen curve under these swellings. Troughs on fourth segment deep and narrow, those of third segment deep, but with shallow sides. Area between first two pairs of vittae strongly curved longitudinally as well as transversely. Abdomen a little carinate from between median to between anterior Vittae. The dark part of first segment coarsely punchte, and with a thin covering of short white hairs which curve outwards from the median line on each side, remainder of segment impunctate. Triangular patch on second segment covered with large, close punctures which superficially resemble sculpturation, but out of which no hairs arise; a few punctures and some sparse, recliuate, black hairs on remainder of segment. Towards anterior corners of third segment a few punctures out of which arise fine sparse, reclinate, white hairs, rest ofthe segment, behind the anterior vittae, lacks sculpturation. Some reduced punctures present, especially towards sides; hairs lacking over median half but some reclinate black hairs present on sides. Fourth segment similar to third, but with very few punctures, appearing very smooth as a result; some reclinate, black hairs on the sides. Genitalia (fig. 26): Epandrium elongated and about twice as long as deep, its lower posterior corner broadly rounded. Cerci very prorninent, and stand well above upper margin of epandrium. Styles about one-and-a-quarter times as long as epandrium is deep, quite broad and flattened, with subparallel margins, a bluntly pointed distal end and a slightly swollen base. Inferior claspers greatly enlarged and as long as epandrium is deep, dorsally produced into very long, flat, blade-like lobes which twist inwards a little at the tip. Ventrally they are produced into short, sharply truncated lobes which are broadened on inner surface into distinct, almost horizontal faces. Superior lobes borne on thin, sharply pointed processes. Lower surface of penis-sheath bears a median, ventral projection that is flattened laterally and subrectangular in shape.

Length 7.0 mm.

Holotype male, CEYLON: Velverry, 18.i. 1891 (Lt.-Col. Yerbuy). In the British Museum (Natural History), B.M. 1892-192 .

Female.-Head with a black from having blue-grey reflections. Strips of tomentum widened above, upper ends bending inwards, pointed and hook-like. Antennae stand on a dark brown base, their two basal segments very dark, and third segment darker than in holotype. Vertex black with strong cyanescent reflections. Scutellum yellow on a little more than apical third. Abdomen (fig. 29) coloured like that of holotype, with the following differences: triangular patch on second segment extended on both sides into thin, long curved arms which follow the border of fist segment, and which are not complete,continuing apically as a series of about ten dark spota around some punctures; dark areas on sides of second segment not extending diagonally acrw segment to end in its corners,but uniformly wide throughout, ending on posterior margin of second segment; abdomen is piceous behind first pair of vittae. Shoulders prominent, and margim of abdomenparallel as far back as first pair of vittae. Troughs on third and fourth segments very deep, narrowieh and distinct. Abdomen triangular in cross-section through second segment,more rounded through third segment, and much more rounded through fourth segment. A moderately developed sculpturation present on third and fourth segments. Fourth and Gth sternites black and shining.

Length 7.6 mm.

Allotype female, CEYLON: Mahagany, 30.xi.1890 (Lt.-Col. Yerbury). In the British Museum (Natural History), B.M. 1892-192 .

Paratypes: INDIA: Jubblepore , 15.xi. 1907, 1 ♂ ex coll. Brunetti, B.M. 1927-184 . CEYLON: Mahagany, 30.xi. 1890, 1 ♂ (Lt.-Col. Yerbury), B.M. 1892-192 ; Trincomali , 20.iii.1891, 1 ♂ (Lt.-Col. Yerbury), B.M. 1892-192 .

The head of the paratype from Trincomali is missing. The dark colour of the antennae, especially of the two basal segments which are almost black, is a noticeable feature of the other two paratypes. All three specimens differ from the holotype in having the abdomen with a strong admixture of brown behind the first pair of vittae; in the specimen from Trincomali this region is almost pure brown. They differ, too, in having distinct punctures on the third and fourth segments. There are some slight differences in the genitalia of each specimen, these involve the styles, which may be truncated or a little rounded apically, and which in all three paratypes have the upper margin a little sinuous.

Remarks.-This species is easily distinguished by the characters given in the key above. From the nature of the abdomen of the male and of the male genitalia it seems that P.yerburiensis is a rather isolated species within the complex. There seems to be considerable variation in size between individuals of this species.