Silba Macquart
Creators: name: Macgowan, Iain
Publisher: name: Zenodo
Year: 2005
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Lonchaeidae
Silba

description: GENUS: SILBA MACQUART, 1851: 277
Silba arcana McAlpine 1960: 369
DISTRIBUTION: Recorded by McAlpine (1960), who figured the male and female genitalia, from Zimbabwe. New to Namibia and Zambia.
MATERIAL EXAMINED: NAMIBIA: 4 males, 4 females, Katima Mulilo District, Salambala campsite, 17°50’01”S, 24°36’09”E, 26–28.ii.2001, A.H. Kirk­Spriggs & E. Marais, Malaise trap; 1 male, Tsumeb District, Mannheim Research Station, 19°10’10”S, 17°45’33”E, 31.i–07.ii.2000, A.H. Kirk­Spriggs, Malaise trap, mango plantation; 1 male, Tsumkwe District, Kano Vlei, 3 km N of, 19°17’15”S, 20°21’03”E, 19.xii.1998, [A.H.] Kirk­Spriggs, [E.] Marais & [D.J.] Mann, at light, dry woodland; 1 male, Tsumkwe District, Xawasha pan, 2 km W, 19°09’57”S, 20°52’55”E, 26–27.xii.1998, [A.H.] Kirk­ Spriggs, [E.] Marais & [D.J.] Mann, Malaise traps; 1 male,
ZAMBIA: 1 male, Choma, 5km S, 16 49'S, 26 55'E, 15.iii.1993, E. Marais. All specimens in National Museums of Namibia, Windhoek.
Silba budongo sp. nov.
Description. Male: Head: Eyes bare. Frons almost parallel sided, approximately half the width of an eye, subshining and flat with short hairs which are one quarter as long as the orbital bristle over most of the frons, longer hairs present on anterior margin just above lunule. Orbital plates shining and bare. Lunule with five hairs. When seen from above lunule, face and parafacials slightly silvered. Anterior genal setae extending anteriorly along the mouth margin in a single row of five hairs, the two basal ones being the strongest hairs on the genae, twice as long as the other hairs. Antenna entirelly black: first flagellomere three times longer than it is deep, reaching down over the mouth edge. Aristal plumosity at its maximum extent equal to the depth of the first flagellomere.
Thorax: Thoracic disc shining in contrast to the rather heavily dusted scutellar disc. One propleural and one hair­like stigmatical bristle. Anepisternum with three strong anterior bristles and four strong posterior bristles. Katepisternum with two strong bristles. Scutellum heavily dusted on the disc, bare dorsally, on the margins between the strong lateral and apical bristles, with two hairs on one side and three on the other, a crossed pair present between apical bristles, all these hairs short, only about one fifth the length of the apical bristles. Squamae and fringes pale yellow, wings slightly fumose, outer crossvein slightly bent. Wing length 4.5mm. Legs all black.
Male genitalia: Fig. 2; 3,4,5. In lateral view epandrium higher than it is broad, rather flat on ventral and anterior surfaces, with a semi­circular excavation anterodorsally, bearing moderately long hairs posteriorly and ventrally. Cerci tall, narrow and rounded, at least half the height of the epandrium, bearing moderately long hairs over most of their surface. Surstylus extending beyond the shell of the epandrium as a spike­like process anteriorly and as a small rounded projection posterioventraly. In ventral view surstyli with a row of fine hairs along their ventral margins, these hairs becoming longer and stronger posteriorly. Basal lobe with six small black teeth, a pair of downward pointing spicules situated just below the base of the cerci. Aedeagus a simple J­shaped tube with a narrow band of spicules present between the basal and apical portions
Female: Unknown.
Differential diagnosis. With entirelly black legs, pale squamal fringe and a rather simple aedeagus with spicules this species shows similarities to Silba fraterna McAlpine, 1956 known from Kenya and South Africa. It can be distinguished from this species by the bare eyes while they are “sparsely but uniformly pubescent” in S. fraterna, and; the plumosity of the arista is equal to the depth of the first flagellomere, it is only half this width in S. fraterna.
TYPE MATERIAL: Holotype male. UGANDA: Budongo Forest, 14 xi. 1972, H. Gønget leg.
Only known from the holotype. Specimen in the Zoological Museum Copenhagen.
Etymology. The specific epithet refers to the locality (Budongo Forest) where this species was collected.
Silba calceus sp. nov.
= Silba virescens Macquart? of McAlpine, 1960.
Description. Male: Head: Eyes bare. Frons narrowing only slightly from level of the ocellar triangle to level of antennal sockets where it is approximately half as wide as an eye, flat and subshining with short hairs which are one quarter as long as the orbital bristle over most of the frons, longer hairs present on anterior margin just above lunule, subshining and flat. Orbital plates shining and bare. Lunule rather brownish orange with about eight hairs. When seen from above face and parafacials slightly silvered. All hairs on the genae rather short, none longer than the depth of the first flagellomere. Anterior genal hairs extending anteriorly along the mouth margin in a single row of six hairs, the two or three posterior ones being the strongest hairs on the genae but not noticeably longer than the others. Palps broad, at their base wider than the depth of the first flagellomere. First flagellomere three times longer than it is deep, reaching down over the mouth edge; black apart from an orange area on inner surface at base. Aristal plumosity at its maximum extent just over half the depth of the first flagellomere.
Thorax: Thoracic disc shining but dusted on the outer margins, bearing hairs less than half the length of the orbital bristle. One propleural and one hair­like stigmatical bristle present. Anepisternum with two strong and below these two moderately strong anterior bristles and three strong posterior bristles. Katepisternum with two strong bristles, the anterior one slightly weaker than the posterior, no hairs behind or below these bristles. Scutellum heavily dusted on the disc, bare dorsally, on the margins between the strong lateral and apical bristles with one hair on one side and three on the other, three hairs present between apical bristles, all these hairs short, only about one sixth the length of the apical bristles. Squamae and fringes whitish, wings with membrane clear. Wing length 3.75mm. Legs all black.
Male genitalia: Fig. 3; 1,2,3. Epandrium taller than it is wide, rather flat on the ventral surface and with a semi­circular excavation anterodorsally, bearing hairs at the posteroventral angle and along the ventral margin but none of these particularly long or strong. Cerci forming a rather rounded club, about half the height of the epandrium, the club bearing short hairs. Surstylus extending beyond the shell of the epandrium posteroventrally as a small rounded process, anteriorly as a characteristic shoe­shaped process. In ventral view the surstylus is produced into rounded lobes posteriorly, this bearing a row of fine hairs on its margins, basal lobe bearing four short black teeth. Aedeagus two­segmented forming a simple J­shape, basal and apical portions slender, apical portion with spicules at the tip.
Female: Unknown.
McAlpine (1960) described and illustrated this species from a single male in his review of South African Lonchaeidae under the name of Silba virescens, but added a question mark after the name showing that he was unsure that this was indeed the true S. virescens. In light of subsequent work on the taxonomy of Silba it is now apparent that the species described by McAlpine is not S. virescens Macquart and as far as I can ascertain the status of this species described by McAlpine has never been clarified. It is however, based on the characters of the male genitalia with its “shoe­like” anterior projection of the surstyli beyond the margin of the epandrium, apparent from McAlpine’s illustration, an easily recognisable species and its occurrence in the Namibian collections has prompted to me clarify its status. I therefore assign it a new name.
TYPE MATERIAL: Holotype male Namibia: Opuwo District. Ruacana area, 17 26’ S 14 9’ E, 14.iii.1997, A.H. Kirk­Spriggs. Malaise trap in mango plantation. Specimen in the National Museums of Namibia, Windhoek.
The specimen described by McAlpine (1960) from Natal, South Africa, was reared from a decaying avocado and is in the South African National Collection.
Etymology. The specific epithet is derived from the Latin calceus, referring to the shoe­like anterior projection of the surstylus.
Silba figurata sp.nov.
The holotype is slightly damaged with some of the main bristles being absent.
Description. Male: Head: Eyes bare. Frons almost parallel sided, pollinose and bearing short hairs no more than one quarter the length of the orbital bristle, with some slightly longer ones present on the anterior margin just above the lunule. Orbital plates shining and bare. Lunule slightly silvered with four hairs on each side, face shining black. Antennae entirelly black: first flagellomere three times longer than it is deep reaching down over the mouth edge. Arista with plumosity at its maximum about as wide as the depth of the first flagellomere. Anterior hairs on the genae extending along the mouth edge as a single row of four hairs, the posterior two of these being the strongest hairs on the genae but not markedly stronger than the others. Palps almost as deep as the first flagellomere.
Thorax: shining on the disc with short hairing. One propleural and one stigmatical bristle. Anepisternum with several bristles missing but apparently with two? strong anterior and two? strong posterior bristles. Katepisternum with two strong bristles. Scutellum shining, bare dorsally, margin with three hairs between strong lateral and apical bristles and two hairs between apical bristles, these hairs rather long being almost a third as long as the bristles.
Squamae and fringes yellow, wing membrane slightly fumose. Wing length 4.0mm. Legs entirelly black
Male genitalia; Fig. 3; 4,5,6. Epandrium taller than it is wide, anteriorly excavated, bearing hairs along the posterior and ventral margins but none of these exceptionally long or strong. Cerci rather large and triangular in shape, sclerotised apically but membranous basally, bearing a covering of moderately long hairs. Surstyli with a close row of hairs along the ventral margin, posteroventral projection rather small and rounded, bearing a few spicules on it’s inner surface, main lobe bearing four strong, blunt black teeth arranged in an angular row, basal lobe detached and forming a column­shaped process at the base of the cerci bearing three teeth in a vertical row, the basal one sharp and defined the upper two broader, more rounded processes, in lateral view this lobe forming a very characteristic F­shape due to the two large upper projections. Two small spinules also present below the basal lobe. Surstylus also projecting anteriorly beyond the shell of the epandrium as a slender curving process. Aedeagus rather simple, long and slender forming a rather open Jshape, with slender apical portion and thicker basal portion, no spicules obvious on basal part.
Female: Unknown.
Differential diagnosis. With black legs, pale squamal fringe, and the surstylus having a detached basal lobe bearing projections this species shows closest affinities to S. ungulifera McAlpine, 1964 from Madagascar. It is distinguished from that species by the fact that the basal lobe does not bear two talon­like teeth and that the aedeagus is long and slen­ der rather than the short and stout one of S. ungulifera.
TYPE MATERIAL: Holotype male. UGANDA: Budongo Forest, 14 xi. 1972, H. Gønget leg.
Only known from the holotype. Specimen in the Zoological Museum Copenhagen.
Etymology. The specific epithet refers to the figure like shape of the projections on the basal lobe of the surstylus.
Silba gongeti sp.nov.
The face has collapsed inwards in the holotype making descriptions of its structure difficult.
Description. Male: Head: Eyes bare. Frons matt black and flat bearing short hairs with longer hairs present on anterior margin just above lunule. Orbital plates shining and bare.
No noticeably strong hairs on the genae. Antennae entirely black; first flagellomere two and a half times longer than it is deep, reaching down over the mouth edge. Aristal plumosity at its maximum three quarters the depth of the first flagellomere.
Thorax: disc slightly dusted bearing hairs which are at most one third the length of the orbital bristle. One propleural and one hair­like stigmatical bristle. Anepisternum with two strong anterior bristles and three strong posterior bristles. Katepisternum with two strong bristles, anterior one slightly weaker. Scutellum dusted on the disc, bare dorsally, on the margin with one hair between the strong lateral and apical bristles. Squamae and fringes whitish, wings clear with yellow veins. Wing length 3.0 mm. Legs all black.
Male genitalia: Fig. 3; 7,8,9,10. In lateral view epandrium broader than it is high, with long hairs along the posterior margin and shorter ones ventrally. Cerci more than half the height of the epandrium, rather club­shaped bearing moderately long hairs on apical portion. Surstylus, in lateral view, extending from shell of epandrium posteroventrally as a rounded triangular process, in ventral view with short, strong hairs along the ventral margin, basal lobe forming a rounded process bearing seven strong black teeth. Aedeagus complex, with a ploughshare­like basal portion, which is smooth below, a pair of median processes which are slightly serrate apically and a thin straight apical portion.
Female: Unknown.
Differential diagnosis. The broad epandrium and the toothed, rounded basal process of the surstylus indicate that this species has affinities with Silba virescens Macquart, 1851 a relatively widespread species and S. rastellifera McAlpine, 1964 known from Mozambique The male genitalia of S. rastellifera were illustrated by McAlpine (1975). The complex aedeagus of S. gongeti is similar to that of S. rastellifera but the latter species has numerous small spicules on the base of the aedeagus and much shorter median processes.
TYPE MATERIAL: Holotype male. UGANDA: Budongo Forest, 1000m, 31°31– 33’E, 1° 39–45’S, 23–30.ix.1973, H. Gønget leg. Only known from the holotype. Specimen in the Zoological Museum Copenhagen.
Etymology. The specific epithet refers to the collector (H. Gønget) of the holotype.
Silba namibia sp. nov.
Description. Male: Head: Eyes bare. Frons half the width of an eye, narrowest point at level of top of lunule, widening very slightly above and below this point. Frons covered in rather short dark hairs, the majority of those on the upper and mid frons only one third the length of the orbital bristle, a few longer hairs just above the lunule, these half the length of the orbital bristle. Lunule with four setulae, two on each side. Orbital plates shining, no hairs present above the orbital bristle. Antennae entirelly black; first flagellomere long, three times as long as deep and just reaching past the mouth edge.
Arista with plumosity just slightly wider than the first flagellomere. Lunule, parafacials and face all silver pollinose. A single row of five to six anterior genal bristles extending in a single row along the mouth edge, none of these significantly stronger or longer than any of the others. Genae relatively narrow only slightly wider than the depth of the first antennal flagellomere.
Thorax: one propleural and one stigmatical bristle. Prothoracic episternum haired. Two pairs of dorsocentral bristles, one pair of acrostichals situated near posterior margin of thoracic dorsum. Two strong katepisternal bristles, anterior one slightly weaker than the posterior, no hairs present below or behind them, this sclerite otherwise bare apart from six to eight hairs on the upper anterior corner. Anepisternum with three strong anterior and two strong posterior bristles. Thoracic dorsum with rather short coarse hairs these at most half the length of the orbital bristle. Scutellum with disc pollinose contrasting with the shining black thoracic dorsum. Scutellum with four to five hairs between lateral and apical scutellar bristles, no hairs between the apical bristles. Lateral bristles much nearer the base of the scutellum than they are to the apical brisltes.
Squamae including margins and fringes golden yellow. Wing with crossvein R­M occurring before the level of the intercostal space, wings slightly fumose. Wing length 4.0mm.
Legs black but basal tarsomeres golden brown, other tarsomeres becoming progressively darker.
Male genitalia: Fig.4; 1,2,3,4. Epandrium one and a half times higher than it is broad, bearing a series of long hairs along its ventral margin. Cerci tall and narrow, slightly more than half as tall as the epandrium, bearing short hairs ventrally and posteriorly. In ventral view epandrium with eight strong black teeth exposed on ventral margin. Pregonites long and tall with curved apices. Aedeagus bilobate with a larger ventral lobe partially enveloping the finger like inner process. The ventral lobe is relatively broad and only slightly excavated at the apex, the apical margin bearing a few spicules, a few spicules also present on the basal part of the ventral lobe. The inner process is subequal in size and length to the ventral lobe.
Female with usual sexual differences; frons about as wide as an eye.
Differential diagnosis: The combination of partly yellow tarsomeres, tall epandrium and cerci and surstyli with teeth exposed on the margin show that S.namibia belongs to the group of species which includes S. admirabilis McAlpine,1956, S. apodesma McAlpine, 1960 and S. pappi, Soós 1977. Within the African species of Silba this species is comparable at present only to S. apodesma. S. namibia is similar in many respects to S. apodesma sharing the yellow basal tarsomeres and the broad female ovipositor. It clearly differs, however, in characters of the male genitalia, in particular the aedeagus.
S. namibia differs from the closely related S. apodesma by the following character states: the orbital plate bears only the orbital bristle with no additional hair or hairs being present, the lunule and face have a silvery tomentum, in S. apodesma the lunule is orangebrown, in S. namibia sp. nov. the length of the plumosity on the arista is approximately equal to the depth of the first flagellomere, whilst in S. apodesma the length is approximately only three quarters the depth of the first flagellomere.
In the male genitalia the aedeagus is in general similar to S. apodesma, of which the male genitalia were illustrated by McAlpine (1960), in that it is bilobate with a larger ventral lobe partially enveloping the inner process. In S. namibia, however, the ventral lobe is not bifurcate at the apex as in S. apodesma but is relatively broad and only slightly excavated, this area bearing a few spicules. The inner process in S. namibia is subequal in size and length to the ventral lobe whilst in S. apodesma the inner process is shorter than the ventral lobe. The pregonites in S. namibia are long and narrow whilst in S. apodesma these are much shorter.
I have examined the shape of the female ovipositor but there seems to be no recognisable differences between the two species, distinction between them being made by the presence or absence of hairs on the orbital plate.
There is some confusion between details given by McAlpine (1960) in the type description of S. apodesma and the characters used to distinguish it in the key to African Silba included in the paper. In the key (p.364) S. apodesma is distinguished from all the other African Silba species by the combination of yellow tarsomeres and having one or more hairs situated on the orbital plate above the orbital bristle. However, in the type description of S. apodesma (p.368) McAlpine stated “orbital plate bare above orbital bristle”. Having examined the paratype of S.apodesma from the Natal Museum I can confirm that S. apodesma does have a hair or hairs on the orbital plate above the orbital bristle.
TYPE MATERIAL: Holotype male, NAMIBIA: Katima Mulilo Dist. Salambala camp site, 17°50’01”S 24°36’09”E, 22–24.ii.2001, A.H. Kirk­Spriggs & E. Marais, Malaise trap’.
Paratypes
Katima Mulilo District, Salambala camp site; 17 50’01”S 24 36’09E, 22–28.ii.2001; A.H.Kirk­Spriggs and E.Marais. Malaise Trap 9 males 69 females
Katima Mulilo District, Iseke turnoff at: 17°50’45”S 24°26’37”E, 02.iii.2001, A.H. Kirk­Spriggs, sweeping flooded pan. 1 female.
Katima Mulilo District, Salambala, 4km NE of 17°49’21”S 24°36’07”E 25.ii.– 01.iii.2001, A.H. Kirk­Spriggs & E. Marais, Malaise trap sample’ 2 females.
Specimens in the National Museums of Namibia, Windhoek.
Etymology. The specific epithet refers to the country (Namibia) in which this species was collected.
Silba plumosissima (Bezzi 1919: 247) (Lonchaea)
DISTRIBUTION: New to Namibia. Widely distributed in Africa, from South Africa to Nigeria ..The male genitalia of this species were figured by McAlpine (1960).
MATERIAL EXAMINED: NAMIBIA: 1 male, Skeleton Coast Park, Kunene River Mouth, 17 15’97”S, 11 46’83”E, 17–18.iii.1998, A.H. Kirk­Spriggs, sweeping marginal grasses; 2 males, Opuwa District, Epupa, 35 km E: Kunene River, 17°03’37”S, 13°29’32”E, 09–11.x.1999, [A.H] Kirk­Spriggs, [T.] Pape & [W.] Hauwanga, Malaise trap, shaded woodland). Specimens in the National Museums of Namibia, Windhoek.
Silba quadridentata sp. nov.
Description. Male: Head: Eyes bare. Frons subshining and flat, narrowing slightly from level of ocellar triangle to level of antennal bases, bearing hairs which are one third as long as the orbital bristle over most of the frons, longer hairs present on anterior margin just above lunule. Orbital plates shining and bare. Lunule with two hairs on each side.
When seen from above lunule and face slightly silvered. Anterior genal hairs extending along the mouth margin in a single row of four hairs, the two posterior ones being the strongest hairs on the genae but not markedly stronger than the others. Antenna entirelly black; first flagellomere three times longer than it is deep, reaching down over the mouth edge. Aristal plumosity at its maximum slightly greater than the depth of the first flagellomere. Palps as broad as the depth of the first flagellomere.
Thorax: thoracic disc shining, bearing hairs which are at most half the length of the orbital bristle. One propleural and one hair­like stigmatical bristle. Anepisternum with three strong anterior bristles on one side and two on the other, three strong posterior bristles. Katepisternum with two strong bristles, anterior one slightly weaker. Scutellum dusted on the disc, bare dorsally, the margins between the strong lateral and apical bristles with one hair on one side and two on the other, two hairs present between apical bristles, all these hairs short, only about one sixth the length of the apical bristles. Squamae and fringes whitish, wings slightly tinged brown. Wing length 4.5mm. Legs all black.
Male genitalia: (Fig. 5. 1,2,3,4.) In lateral view epandrium higher than it is broad, rounded on ventral margin, with a small semi­circular excavation anteriorly, bearing a tight group of long straight hairs at the posteroventral angle with shorter ones along the ventral edges. Cerci tall, at least half the height of the epandrium, sclerotised ventrally but membranous dorsally, bearing moderately long hairs on apical portion. In lateral view surstylus extending as a narrow round­tipped process anteriorly, in ventral view with a row of strong curved spicules. In posterior view basal lobe of surstylus with two very strong separate teeth and with an adjacent four toothed squarish process. Aedeagus rather simple, divided into a basal part and a straight and thin apical portion.
Female: Unknown.
Differential diagnosis. With black legs, pale squamal fringe, slightly fumose wings and a rather simple aedeagus this species shows similarities to Silba figurata sp. nov and Silba uganda sp. nov. The distinctly toothed basal lobe of the surstylus easily distinguishes this species from them.
TYPE MATERIAL: Holotype male. UGANDA: Budongo Forest, 1000m, 31°31– 33’E, 1°39–45’S, 23–30.ix.1973, H. Gønget leg. Only known from the holotype. Specimen in the Zoological Museum Copenhagen.
Etymology. The specific epithet refers to the four­toothed process on the surstyli of the male genitalia.
Silba spatulata sp. nov.
Description. Male: Head: Eyes bare. Frons, relatively narrow, narrowing from the level of the ocellar triangle to a point half way between the ocellar triangle and the base of the antennae, where it is approximately one quarter the width of an eye, dull black in colour and bearing only short hairs which are less than one quarter the length of the orbital bristle. Orbital plates shining black, without hairs. Antenna entirelly black, first flagellomere three times as long as it is broad, reaching down over the mouth margin.. Arista yellowish at the base with very long plumes, at their greatest width the longest plumes being one and a quarter times as wide as the first antennal flagellomere. Face and parafacials shining black. Genae with relatively stout and short bristles, these extending in a single row of five or six bristles anteriorly along the mouth edge, the basal of these bristles being the strongest on the genae. Palps black, about as wide as the depth of the first flagellomere.
Thorax: Thoracic disc subshining black and bearing short hairs, the longest of these being no more than one third the length of the orbital bristle. Sclerites on the side of the thorax slightly dusted, the anepisternum with four strong anterior bristles and three strong posterior bristles, the remainder of the surface of this sclerite covered in long hairs most of which are three quarters as long as the strong bristles. One propleural and one stigmatical bristle. Katepisternum with two strong bristles, these equally strong and lying level with each other, no hairs posterior to or below these but hairs scattered over the anterior part of the sclerite.
Scutellum bare on the disc, on the margin in addition to the four strong bristles with five hairs between the lateral and apical bristles, these hairs almost in a single row, four hairs present between the apical bristles.
Wings with veins yellowish, wing membrane clear but with a slight yellow tinge, squammae and squamal fringes whitish. Legs entirely black.
Male genitalia: (Fig. 4. 5,6,7,8.) Epandrium twice as high as it is wide, ventral edge flat, anteriorly with a rather broad lobe, moderately haired at the posteroventral corner and on the anterior lobe which also bears a few tiny hairs amongst the longer ones. Cerci relatively small, only about one third the depth of the epandrium, bearing a few moderately long hairs. Surstylus only extending beyond shell of epandrium as a narrowly rounded process anteriorly, its ventral edges with a row of spinules, these small anteriorly but posteriorly these forming a row of five longer spines, basal lobe with six small, rounded black teeth. In the area directly below the cerci with three small black teeth present and also two small spinules. Aedeagus short and stout, in lateral view apical part broadening towards the tip, in ventral view rather spoon­shaped fitting into the basal portion which surrounds the stem.
Female: Unknown.
Differential diagnosis. This species with its black legs, pale squamal fringe and short, two segmented aedeagus is perhaps most closely related to Silba laevis (Bezzi, 1920) which is known from several African countries: its distinct aedeagus however easily distinguishes S. spatulata from other externally similar species.
TYPE MATERIAL: Holotype male, TANZANIA: East Usambara, Amani, at Sigi River, 500m, 5.ii.1977, H. Enghoff, O. Laumholdt, O. Martin leg. Only known from the holotype. Specimen in Zoological Museum, Copenhagen.
Etymology. The specific epithet refers to the spatulate shape of the apical part of the male aedeagus.
Silba uganda sp.nov.
Description. Male: Head: Eyes bare. Frons almost parallel sided, subshining black bearing very short hairs which are at most one quarter as long as the orbital bristle, a few longer hairs present on the anterior margin above the lunule. Orbital plates bare. Lunule slightly silvered with orange brown colour beneath, with six hairs; parafacials slightly silvered, face shining black. Anterior genal hairs extending along the mouth edge as a single row of six or seven hairs, gradually getting longer from the anterior to the posterior with the posterior two or three in this row being the longest hairs on the genae, but these not markedly longer than the other hairs. Palps at their widest part not as wide as the depth of the first flagellomere.
Antennae entirely black, first flagellomere three times as long as it is deep, reaching down over the mouth margin. Arista with plumosity at its widest point almost as wide as the depth of the first antennal flagellomere.
Thoracic dorsum shining, with hairs longer, most just less than half the length of the orbital bristle. Thoracic pleura slightly dusted. One propleural and one hair­like stigmatical bristle. Anepisternum with three strong anterior and three strong posterior bristles. Katepisternum with the two strong bristles equally long and strong, no hairs behind or below these. Scutellum with disc slightly dusted, on margin between apical and lateral bristles with two hairs on one side and four on the other, two crossed hairs between apical bristles.
Squamae and fringes yellowish. Wing veins yellow, membrane light fumose. Wing length 5.0mm.
Male genitalia: (Fig. 5. 5,6,7,8.) Epandrium higher than it is wide, rather flat on the ventral edge, semi­circular excavation anterodorsally, bearing hairs at posteroventral corner and along ventral margin. Cerci rather angular with a rather acute point basally, with moderately long hairs on apical portion ventrally and dorsally. In lateral view surstylus extending beyond the shell of the epandrium anteriorly and posteroventrally as a small rounded process. In ventral view surstylus with large rounded process bearing strong spine­like hairs, otherwise margin of the surstylus slightly emarginated bearing long fine hairs, basal lobe black and chitinised, inwardly pointing, on one side bearing three stong teeth in a duck’s foot shape, on the other side apparently only two. Aedeagus a simple Jshaped tube with a few spicules at the base of the apical portion.
Female: Unknown.
Differential diagnosis: With all black legs, pale squamal fringes and a simple J­shaped aedeagus this species shows similarities with other African species such as S. laevis (Bezzi, 1920). It is however easily distinguished by features in the male genitalia such as the surstylus with large posteroventral lobes and the inwardly pointing basal lobe with its large teeth: the aedeagus is also relatively slender in its basal portion. The light brown wings also serve to distinguish this species from its close relatives
TYPE MATERIAL: Holotype male. UGANDA: Budongo Forest, 1000m, 31°31’– 33’E, 1°9’–45’S, 23–30. ix. 1973, Hans Gønget leg. 1 Paratype male with the same data. Specimens in Zoology Museum Copenhagen.
Etymology. The specific epithet refers to the country (Uganda) in which this species was collected.
Silba virescens Macquart 1851: 277
DISTRIBUTION: New to Namibia. Widely distributed over much of Africa and southern Europe. This species was described as S.pectita McAlpine, 1960 and the male genitalia were illustrated by McAlpine (1960) (see discussion under S.calceus above).
MATERIAL EXAMINED: NAMIBIA: 1 male, Katima Mulilo District, Salambala campsite, 17°50’01”S, 24°36’09”E, 22–24.ii.2001, A.H. Kirk­Spriggs & E. Marais, Malaise trap; 1male, Tsumeb District, Mannheim Research Station, 19°10’10”S, 17°45’33”E, 31.i–07.ii.2000, A.H. Kirk­Spriggs, Malaise trap, mango plantation. Specimens in the National Museums of Namibia, Windhoek.
description: Published as part of Macgowan, Iain, 2005, New species of Lonchaeidae (Diptera: Schizophora) from central and southern Africa, pp. 1-23 in Zootaxa 967 on pages 8-22, DOI: 10.5281/zenodo.171270