Paragus crenulatus Thomson, 1868

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 : 408-413

Paragus crenulatus Thomson, 1868 .

This species was erected by Thomson on material from unspecified localities in China. From his description it would seem to differ from P. serratus as then understood in having extensively dark femora, longish antennae, the mesonotal stripes narrowed behind, and the wings yellowish at the base.

I have specimens before me from the following localities: SARAWAK: foot of Mt. Dulit at Junction of rivers Tinjar and Lejoh , 22. viii.1932, 11. x. 1932, 3 ♂, 1♀ (B. M. Hobby, A. W. Moore), B.M. 1933-254 . HONGKONG: Hong Kong Peak, 22-24. ix. 1937,1300 - 1600 ft.; University Grounds , 1-10. xii. 1937, 2 ♂, 4 ♀ (G. M. Herford), B.M. 1938-426 . JAVA: Pekalongan , iv.1907, 1 ♂, C. H. Curran Collection, ACC. 31144 . DUTCH NEW GUINEA: Cyclops Mts., Sabron , 930 ft., iv. 1936,l ♀ (L. E. Cheesman), B.M. 1936-271 . CEYLON: Colombo, 14. vi. 1891, 1 ♂ (Lt.-Col. Yerbwy), B.M. 1892-192 . CELEBES: Moho , 4000 ft., i.1936, 1 ♀ (L. E. Clzeesman), B.M. 1936-271 . INDIA: Calcutta , xi. 1908, 1 ♂, 20.xii. 1908, 2 ♂, ex coll. Brunetti, B.M. 1927-184 . MALAYA: Serdang , 17.xii.1923, 1 ♀ (G. H. Corbett, B. A. R. Gater), B.M. 1924-436 . Singapore, 23. v. 1911, 1 ♀ (R. Hamitsch), B.M. 1936-173 . Selangor, Kuala Lumpur , 12.xi. 1924,l $ ♀ (H. M. P.ndlebury), B.M.1925-56 . SIAM: Bangkok, 19.vi.1929, 1 ♂, 1 $ ♀ (W. R. S. Ladell), B.M. 1930-215 . All except the male from Java are in the British Museum.

This is one of the most widely distributed species of the complex. It ranges over the whole of the Oriental Region and Austro-Malayan Subregion. The species which Keiser (1952) recorded from Sumba, Sumbawa, Floresand Timor as P. serratus , and which he notes to occur alsoin the PhilippineIslands, Formosa and China, is almost certainly P. crenulatus . It is probably the species which occurs in Australia.

There is considerable variation within the species. Each ofthelarger islands has a slightly different form, and there are small differences between specimens from Malaya, Siam, India and Hong Kong. P. crenulatuscould probably be divided into several subspecies; I lack suEcient materialt o attempt this.

The following description is based on the specimens from Hong Kong.

Males.-Hmd: Thomson states that the face ofP. crenulatzlsiswhitishone of the males which I have has a flavescent face, translucent,and in some positions with very pale blue reflections; the other male hasa yellow face.

Facial pile thin. Median stripe restricted in one specimen t o theoraltubercle,in the other reaching half-way to antennae: pale brown in both. Oral tubercleconspicuously black, and surrounded by a dark brown strip. Two basalsegmentsvery darkbrown, almost piceous above. Third segment paler, subcylindrical and a littlemorethantwice as long as first two segments.together. Vertex entirely black with violaceousreflections. The two middle stripes of hair on each eye tendto merge, buttheoutermostdistinct though narrow. Thorax: Mesonotum black, with quite strong violaceousreflections and a few faint blue reflections. Mesonotal pile quite long, erect, and shiningyellow: pale yellow on anterior humeri and shining brassy-yellow behind attachmentofwings. Mesonotal stripes pale, rather purplish when seen from above-brassy-yellowwhenviewed obliquely. Stripes unite in front, almost uniformly wide asfarbackasmidwaybetween transverse suture and scutellum, and then narrow rapidly,almostendinginpoints. Basal third of scutellum piceous, the remainderyellowish. One malehaseleven, theothertwelve pale, subequal scutellar teeth (Thomson mentions twelve teeth). Scutellarpiledecidedly longer than that of rest of mesonotum. Legs: Posterior femora testaceousonbasal seventh, yellow on apical quarter, the rest conspicuously dark brown. Posteriortibiae yellow on basal half, then banded with dark brown, and with apicalUthtawnywitha gny sheen. Posterior metatarsi dark crineous, rest of tarsalsegmentssimilarbutmore yellow. The two anterior pairs of femora yellow on apical half,luteousonbasal half. The two anterior pairs of tibiae yellow on basal half, testaceouson therest; thetwo anterior pairs of tarsi reddish-brown. Wings: Membrane suffused with yellowish-brown on the basal half, becoming paler apically. Microtrichia on membrane very dark and conspicuous, and the wing bordered posteriorly by a line which is darker than in the other species. Stigma yellowish-brown, distinctly darker than subcostal cell. Veins heawy and very dark, almost piceoua. Abdomen: Broad and rather flattened, subcarinate. Over the second segment it is triangular in cross-section, less so over succeeding segments. Shoulders prominent, sides curving gradually backwards, forming sharply rounded cornera behind. Shoulders dark fusco-piceous, with some violeceous reflections, this dark colour extending down the margin to apex of second segment, from whence it extends diagomlly across the segment to posterior margin of first segment. Anterior corners and knob-like protuberances of first segment fusco-piceous. Remainder of abdomen brownish-amber, a little reddish behind. Prominent, reclinate, black hairs arising from distinct punctures on second, third, and, to a lesser extent, fourth segment. White hairs present on fist segment,where they are thin and erect; better developed and reclinate on fourth segment, and very well developed on fifth segment. Transverse troughs of third segment well developed, rather deep, with flattened sides. Troughs on fourth segment very shallow and inconspicuous. The vittae which normally occupy these troughs almost absent in one specimen, sparingly developed in the other. Sculpturation present on second to Efth segments. Genitalia ( fig. 17 ): Epandrium not very elongated, and its lower posterior corner bluntly rounded. Cerci rounded and prominent. Each style consists of an enlarged base and a narrow, elongated apical portion ending in a point and with sinuous upper and lower margins. Inferior claspers produced above into a moderately curved lobe which has a truncated end; ventrally tbey are produced into small, anteriorly directed lobes. Superior claspers borne on well developed, broadly rounded processes. A thin ventral projection present on penis-sheath.

Females.-Colour of face variable, being either flavescent, very smoky, translucent yellow, or almost yellow-green. Frons black with some bluish reflections bordered by narrow, linear strips of tomentum that expand at the upper end into a small, inwardly directed, triangular patch. Vertex black with violaceous reflections between ocelli and cyanescent reflections on the side and behind. Number of scutellar teeth varies from eleven to thirteen. Coloration of abdomen ( fig. 20 ) considerably different from that of males described above, and practically the same in each female. Firet segment, including knob-like protuberances, black before the transverse ridge. Second segment wholly black on the sides, this dark colour extending diagonally across to posterior margin of first segment. Remainder of first and second segments, and narrow anterior margin of third segment brownish-amber. A small, black triangular patch in middle of second segment the arms of which in one specimen extend narrowly around entire posterior border of segment. Third segment completely fusco-piceousbehind and between vittae. Fourth segment a little brownish before its vittae, remainder of segment black. Fifth segment dark brown, with irregular dark patches. All three pairs of vittae distinct and complete, though anterior margins of first pair are not clearly defined against the pale colour of anterior part of third segment. Abdomen almost uniformly broad as far back as beginning of third segment; very deep, incompletely carinate, and with slightly flattened sides. Fourth and fifth sternites dark fusco-piceous.

The specimens from Sarawak have yellow faces and prominent facial stripes. The antennae are paler, and the from of the females and vertex of both sexes show strong cyanescent reflections. The thorax has violaceous and metallic cyanescent reflections. The’mesonotal stripes, when seen from above, appear as two faint, purplish strips, scarcely discernible. When the thorax is viewed obliquely the stripes appear to be brassy or slightly cupreous; in all the specimens they fade out just behind the transverse suture. The number of scutellar teeth varies from twelve to fifteen. In two specimens the wings are only moderately suffused with yellow brown, otherwise they are heavily suffused. The genitalia differ in that the styles are more strongly arched on the upper margin, the epandrium is a little more elongated, and the processes supporting the superior claspers are not as well developed. Two of the males have the abdomen red-brown behind the first pair of vittae.

The female from Celebes has a darker face that is slightly tinged with brown. There are very strong cyanescent reflections on the front and vertex. The mesonotal pile is long, fine and bombycinous. The mesonotum is black and shining, with deep cyanescent reflections on the sides. The mesonotal stripes are complete though very thin over their posterior third, they are not very heavy, and are dark brassy yellow. The abdomen is greatly enlarged, almost as broad as long, and nearly circular in outline. The first-segment is almost entirely yellowish-brown, except for a small dark patch below each knob-like protuberance. The area behind the vittae on the third segment is brownish medially, fusco-piceous on the sides. The fourth segment is fuscopiceous except for a narrow, median strip of dark brown. The anterior pair of vittae are inconspicuous, while the two posterior pairs are well developed. The troughs on the third and fourth segments are very shallow.

The female from Dutch New Guinea has a broad, rather flattened abdomen, with sides that curve strongly backwards. The third and fourth segments are conspicuously sculptured. The whole abdomen is a slightly reddish-brown, except for the sides and shoulders of the second segment which are piceous. The fourth and fifth sternites are yellowish-brown. The mesonotal pile is only faintly yellow, and the mesonotal stripes are silvery. The frons, vertex and entire mesonotum have deep cyanescent reflections. The tomentose strips of the vertex are linear and lack inward projections at the upper ends. The tarsi are rather ferruginous. There are eighteen scutellar teeth which are very short except for a few on each side of the scutellum.

The male from Java has very heavy mesonotal stripes which are silverywhite. The sides of the abdomen ( fig. 19 ) are not so curved, and the abdomen is rather carinate. The hob-like protuberances of the first abdominal segment are fusco-piceous with quite strong blue reflections. The sides of the second segment are dark brown. The remainder of the abdomen is a slightly yellowish brown. The troughs on the third segment are narrow and quite deep. The hypopygium is very similar to that of the Hong Kong form, except that the penis-sheath is not so deeply curved below, and the ventral process is very weak.

The hypopygium of the male from Ceylon differs in certain respects from that of the Chinese specimens. The styles are not pointed apically, but bluntly rounded; the upper lobe of the inferior claspers is more attenuated and almost ends in a point; the process supporting the superior claspers is much broader.

The three specimens from Calcutta are rather dark. The abdomen is marked like those of the females from Hong Kong. The mesonotal pile is white, and the mesonotal stripes are complete and silvery. The wings in each case are without any suffusion. The thorax is more coarsely punctate, and has dull violaceous and a few cupreous reflections. The genitalia ( fig. 18 ) differ in having the penis-sheath more broadly curved below, and the styles rounded apically and not enlarged at the base.

The male from Bangkok has no suffusion on the wings, and the veins are not as heavy as in the Chinese form. The thorax has some cyanescent re0ections, and the mesonotal pile is pale yellow. The mesonotal stripes are complete and silvery. The abdomen is coloured like that of the male from Java. The epandrium is about as long as deep, the styles are enlarged at the base, and the upper lobe of the inferior claspers is more produced. The female from the same locality has moderately suffused wings, heavier mesonotal pile and a darkish face; the tomentose strips of the frons are enlarged at the upper end into stout, hatchet-like projections that almost meet in the mid-line.

The posterior femora of both specimens are only moderately dark.

Of the females from Malaya, those from Kuala Lumpur and Singapore have almost clear wings. All have the tornentose strips of the from narrow, with stout, inwardly projecting, beak-like extensions at the upper ends, which almost meet in the mid-line. The specimen from Serdang has heavily suffused wings and has the fourth and fifth abdominal sternites brown. Shortest specimen 5.6 mm., longest specimen 6.8 mm.

Remarks.-This species can usually be recognised by its suffused wings, and by the extensively dark posterior femora. It may be confused with P. serratus (Fabricius) when the wings are clear, but the longer mesonotal pile and darker posterior femora distinguish it from that species. The shape of the abdomen is often characteristic.

Figures

FIGS.17-20.-Paragus crenulatus Thomson. (17) HypopygiumIof male from Hong Kong. (18) Hypopygium of male from Calcutta. (19) Abdomen of male from Java. (20) Abdomen of female from Hong Kong.