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BARTAK:

245-254

Studia dipterologica 11 (2004) Heft 1 · ISSN 0945-3954

Revision of the Rhamphomyia (Megacyttarus) poissoni-gronp (Diptera, Empididae), including the description of two new species
[Revision der Rhamphomyia (Mega cytta rus ) poissoni-Gruppe (Diptera, Empididae) nebst der Beschreibung von zwei neuen Arten] by, Miroslav BARTAK
Prague (Czech Republic)

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Abstract

A revison of the Palaearctic Rhamphomyia (Megacyttarus) poisson i-group is given. Rhamphomyia (Megacyttarus) kovalevi spec. nov. and Rhamphomyia (Megacyttarus) tuberifemur spec. nov. are described. All three species of this group are keyed and illustrated. A key to world groups of the subgenus is provided. Diptera, Empididae, Rhamphomyia, Megacyttarus poissoni-group, Palaearctic region, new species, descriptions, redescription, key, distribution.

Key words

Zusammenfassung Die Arten der palaarktischen Rhamphomyia (Megacyttarus) poissoni-Gruppe werden einer Revision unterzogen. Es erfolgt die Beschreibung von Rhamphomyia (Megacyttarus) kovalevi spec. nov. und Rhamphomyia (Megacyttarus) tuberifemur spec. nov. Aile drei Arten der Gruppe werden in einem Bestimmungsschlussel charakterisiert und abgebildet. Ein Schliissel zu den Gruppen der Untergattung Megacyttarus der Weltfauna erganzt die Arbeit. Stichwiirter Diptera, Empididae, Rhamphomyia, Megacyttarus poissoni-Gruppe, palaarktische Region, neue Arten, Beschreibungen, Nachbeschreibung, Bestimmungsschlussel, Verbreitung

Introduction Megacyttarus is a large subgenus of Rhamphomyia with Holarctic distribution. The subgenus may be separated from all other known species of the Rhamphomyia s. 1. by absence of (at least ventral part) of vertical plate of ejaculatory apodeme (Fig. 4c-f) and trilobate dorsal genital lamella (Figs. lc, 2a, 3c). Moreover, vein RI is swollen in apical part (Fig. 4b). BARTAK (2001) recognised altogether 92 world species, out of them 66 N earctic [all described or redesribed by BARTAK (2002)],24 Palaearctic (20 of them described, two additional described herewith) and 2 Holarctic (both described). The present paper represents continuation of the revision of Nearctic Rhamphomyia (Megacyttarus) (BARTAK 2002), covering fauna of the Rhamphomyia (Megacyttarus) poissoni-group. The complete knowledge on biology and morphology of the subgenus was gathered by BARTAK (2002). In the paper he recognised altogether 5 groups of species (R. scaurissima-group, R. crassirostris-group, R. poissoni-group, R. praecipua-group, and R. argentea-group) based on characters of male terminalia and arrangement of dorsocentral bristles. R. poissoni-group is allied to R. crassirostris-group, both having multi serial dorsocentral bristles, male pregenital segments unmodified, cranial process of dorsal genital lamella present, basal swelling of phallus absent, hypopygium "opened", and "hood" of dorsal genital lamella absent. However, they markedly differ in the shape of phallus which has two outgoing loops in species of R. crassirostris-group, which are absent in species of R. poissoni-group (Figs Id, 2d, 3a), in the presence of dorsal pat of vertical plate of ejaculatory apodeme in R. poissoni-group (Fig. 4d) which is totally absent in all other Megacytta-

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rus-groups including species of R. crassirostris-group (Fig. 4c, e, f), and hind margin of the 8th stemite is straight in R. poissoni-group (Figs 1d, 2d, 3a) however deeply convex (forming hairy outgrowth) in R. crassirostris-group. Moreover, middle lobe of dorsal genital lamella has concave upper margin (having up curved tip) in R. poissoni-group and convex margin (having downcurved tip) in species of R. crassirostris-group and tip of hypandrium is membranose and depigmented in R. poissoni-group (Figs 1b, 2c, 3d) whereas sclerotized and pigmented in R. crassirostris-group. R. poissoni-group is Pa1aearctic in distribution (up to present known only from West Palaearctic) but R. crassirostris-group has Ho1arctic distribution.

Key to world groups of Rhamphomyia (Megacyttarus)
Dorsal lobe of dorsal genital lamella forms an expansion protruding above abdomen cranially, covering at least last tergite (as in Fig. 3a) 2 Dorsal lobe of dorsal genital lamella does not form a process, if so, than it is directed caudally 3 2 (1) Phallus forms two outgoing loops R. crassirostris-group Phallus without two outgoing loops (Palaearctic) R. poissoni-group 3 (1) The 7th tergite enlarged, being much longer than 6th one, genitalia almost hidden betR. praecipua-group wen it and enlarged 8th stemite (Nearctic) The 7th tergite not enlarged. Genitalia "opened", with exposed phallus 4 R. scaurissima-group 4 (3) Dorsocentral bristles uniserial, directed outwards (N earctic) Dorsocentral bristles at least biserial R. argentea-group
1

Material and methods
The terminology including symbols for individual structures follows previous paper of the author (BARTAK 2002). Measurements of the body size, ratios on wing also follow BARTAK (2002) with the exception of ratios on legs, which in terminology follow BARTAK (1985). The broadest diameter of the particular basitarsus was measured exspressing the ratio of length: breadth of basitarsus (Mtx:Mtx). Material depositories: Zoological Museum, Moscow State University (ZMUM), private collection of M. BARTAK (PCMB), Charles University, Faculty of Sciences, Prague (CUP).

Key to males of Rhamphomyia (Megacyttarus) poissoni-group
Face extremely narrow (0.04 mm at midlength), being narrower than front ocellus. Both kovalevi spec. nov, metapleura and abdomen dark haired and bristled Face broader, being at least 0,10 mm long at midlength. Both abdomen and metapleura at least partly pale haired 2 2 (1) Apical part of hind tibia with dorsal bristles which are about 3/4 as long as the length of hind basitarsus. Ventral hairs on hind basitarsus shorter than its diameter (Fig. 3b). Batuberifemur spec. nov, sitarsus of middle leg short haired dorsally Apical part of hind tibia with dorsal bristles which are about 1/4 as long as the length of hind basitarsus. Ventral hairs on hind basitarsus longer than its diameter (Fig. 2b). Basitarsus of middle leg with 2-4 pd bristles which are 2-3 times as long as diameter of basi tarsus poissoni TREHEN
1

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Systematic treatment

Rhamphomyia (M egacyttarus) poissoni-group
Diagnosis (A = apomorphic feature, P = plesiomorphic, inside Megacyttarus) 1. Dorsocentral bristles multiserial (P) 2. Male pregenital segments unmodified (P) 3. Cranial process of dorsal genital lamella present (A) 4. Basal swelling of phallus absent (A) 5. Hypopygium "opened" (P) 6. "Hood" of dorsal genital lamella absent (A) 7. Phallus without outgoing loops in apical part (P) 8. Hind margin of the 8th sternite straight (P) 9. The tip of hypandrium membranose and depigmented (A) 10. Middle lobe of dorsal genital lamella with concave upper margin 11. Vertical plate of ejaculatory apodeme present in the form of short dorsal outgrowth of horizontal plate 12. West palaearctic distribution Anagenetic trends in characters 10-12 are unclear. Character of vertical plate of ejaculatory apodeme seems to be different from other groups of main Rhamphomyia tree and, thus derived. However, it may represent remnants of original lamella and further studies are necessary to elucidate the problem. Characters 1-6 are common with species of the most allied R. crassiros tris- group.

Rhamphomyia (Megacyttarus) kovalevi spec. nov.
(Fig. la-d)

Male. Head: Eyes dichoptic, facets in the upper part of eye much smaller than lower ones. Frons velvety brownish black, 0.06 mm broad above and 0.08 mm below, being 3.6 times as long as broad, bearing 4-5 black hairs on each side which are much longer than frons is broad. Ocellar bristes slightly longer than frons, black, and ocellar triangle with 2 additional hairs. Face brownish black, dark grey pruinose, 0.04 mm broad at midlength, being almost parallel sided and about 8 times as long as broad, bare. Occiput brownish black, dark grey pruinose, sparsely black bristled (bristles arranged almost in two rows), postocular row complete. Antennae black, both basal segments brown, ratio of antenna1 segments = 13: 10: 24: 4. Labrum brown, polished, shorter than head is high. Palpi brown, short, covered with a few rather long hairs. Thorax dark brownish black, grey pruinose, mesonotum almost velvety brownish black, without any stripes. All bristles and hairs are black. Chaetotaxy: 3 hairs on proepistemum, propleura and prosternum bare, 18 biserial, medium thick ac are almost twice as long as the distance between rows of ac and de, 13-14 de are irregularly biserial and of the same character and length as ac, ending in 2 prescutellars, 1 long and strong h (and 5-6 much shorter hairs), 1 ih, 1 ph (1--4 hairs around ph), 3--4 n (3-5 hairs in front part of notopleura), 2-3 sa (2-3 pra hairs), 1 pa, 4 sc, mtpl dark. Legs including coxae brown, pruinose, dark haired and bristled. A very short and fine bristle present in "comb" at tip of hind tibia. Front femur with sparse av and pv ciliation half as long as vertical diameter of femur, dorsal ciliation rather dense and equally short. Front tibia with almost homogeneous pd ciliation as long as diameter of tibia, ventral hairs short. Middle femur with complete rows of about 10 av and 15 pv bristles which are slightly longer than vertical diameter of femur (the longest are av in apical third of femur). Middle tibia with a single subbasal pv, other cilation short and fine (up to as long as diameter of tibia), without bristles. Hind femur (Fig. 1a) with a complete row of av bristles which are slightly longer than vertical diameter of femur and with only slightly shorter ad and d bristles, pv much shorter. Hind tibia (Fig. la) with a single row of dorsal sub equally spread bristles, 7-9 of them are nearly twice a long as diameter

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Fig. la-d: Rhamphomyia (Megacyttarus) kovalevi spec. nov. (Holotype). - a: Hind leg (femur, tibia and basitarsus), anterior view. - b: Hypandrium and phallobase. - c: Dorsal genital lamella. - d: Hypopygium, macerated, lateral view. Scale bars: a = 0.5 mm; b, c = 0.1 mm; d = 0.2 mm.

of tibia, ventral ciliation subequally long as diameter of tibia. Basitarsus of front leg thin and short haired, T1: Mt1 = 2.0, Mt1: Mt1 = 9.0. Basitarsus of middle leg thin and short haired, T2: Mt2 = 2.3, Mt2: Mt2 = 8.0. Basitarsus of hind leg (Fig. 1a) thin, with a few dorsal hairs which are twice as long as diameter of basi tarsus, T3: Mt3 = 2.0, Mt3: Mt3 = 7.5. Wings clear, stigma hyaline, veins pale brown, vein A absent in apical part. Costal bristle long, ax angle 90 0 · M2/D = 1.4, M3/Db = 3.4. Halter brown, squama brown with dark fringes. Abdomen brown, pruinose, tergites 3-6 conspicuously light, being almost silvery (but sparsely) pruinose. Bristles and hairs exclusively dark. Hind marginal bristles on sides of tergites are 2/3 as long as segments, dorsum of tergites short haired (hind marginals about 1/3 as long as segments). Discal hairs shorter than marginals. Terrninalia as in Fig. 1b-d. Length of body 3.7 mm, wing 3.5 mm.

Female. Unknown.
Differential diagnosis: Rhamphomyia (Megacyttarus) kovalevi spec. nov. differs from both remaining species of this group by a number of characters. Beside those given in the key: hind tibia is straight, halter brown, hind femur has no protuberance posteriorly, mesonotum dark, almost velvety brownish black, hind femur with both dorsal and ventral bristles which are at least as long as vertical diameter of femur and midle femur without long pv. There are slight differences in the shape of male genitalia between the above described species and both other species of this group: phallus has no fold preapically, it is only upcurved at extreme tip and cranial process of dorsal genital lamella has short and broad hind margin and straight lower margin (whereas both other species have narrow hind margin and lower

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Studia dipterologica 11 (2004) Heft 1: 245-254 margin distinctly convex) - see Figs l c, 2a, 3c. Moreover, wholly black haired body it is a rare exception among Palaearctic Megacyttarus. This character occurs only in Japanese R. brevicellula SAIGUSA. The species described above seems to be the most primitive member of R. poissoni-group according to plesiomorphic character of leg chaetotaxy and absence of protuberance on hind femur.
Material. Holotype male: RUSSIA, Krasnodarskij kraj, okr. (= district) Severskoj, Ubinskaja, 12.v.1970, leg. V. KOVALEV, deposited in ZMUM. - No further specimens avaiable. Distribution: Russia, West Caucasus. Dates of occurence: May. Derivatio nominis: The species is dedicated to the collector of the Holotype, the late famous Russian dipterist, Valeri G. KOVALEV.

Rhamphomyia (Megacyttarus) poissoni
(Fig. 2a-e)

(TREHEN,

1966)

Rhamphomyia tephraea auct., not MEIGEN, 1822. Megacyttarus poissoni (TREHEN, 1966): Annls, Soc. ent. Fr. (N.S.), 2(3): 627 (Megacyttarus)

Male. Head: Eyes dichoptic, facets in the upper part of eye smaller than lower ones. Frons black to brownish black, very light grey pruinose, 0.10-0.14 mm broad above and 0.10-0.12 mm below, being 1.8-2.5 times as long as broad, bearing 3-8 black hairs on each side which are longer than frons is broad. Ocellar bristes slightly longer than frons, black, and ocellar triangle with 2~6 additional hairs. Face black to brownish black, very light grey pruinose, 0.13-0.14 mm broad at midlength, broadening below, being 1.8-2.5 times as long as broad, bare. Occiput black, light grey pruinose, sparsely black bristled, in lowermost part with a few pale hairs, postocular row nearly complete. Antennae black, both basal segments brown, ratio of antenna 1 segments = 15-19: 9-10: 28-34: 8. Labrum brown, polished, as long as or shorter than head is high. Palpi brown, short, covered with a few dark hairs, preapical bristle sometimes prominent. Thorax black, light grey pruinose, mesonotum with two brown stripes between ac and de bristles and two brown stripes to spots outside of de. Large bristles and hairs are black, small hairs inc!' mtpl pale. Chaetotaxy: 1-9 pale hairs on proepisternum, propleura and pro sternum bare, 13-26 biserial, fine ac are slightly shorter than the distance between rows of ac and de, 14-24 de are irregularly biserial, medium thick and as long as or slightly longer than the distance between rows of ac and de, ending in 2 prescutellars, 1 long black h (and several much shorter pale hairs), 1 ih, 1 ph (1-4 hairs between ih and ph), 2 n (a few pale hairs in front part of notopleura), 2-3 sa (1-3 pra hairs), 1 pa, 2 sc (usually with 2-4 additional short hairs), mtpl pale. Legs: Coxae brownish black, light grey pruinose, mostly pale haired, larger hairs may be dark. Legs brown, pruinose, middle femur and sometimes hind femur anteriorly, hind tarsus on both sides and hind femur posteriorly partly subpolished. Legs both dark and pale haired and bristled, proximal parts of legs mostly dark haired. A very short bristle present in "comb" at tip of hind tibia. Front femur with sparse av and pv ciliation 1/3 as long as vertical diameter of femur, dorsal ciliation more dense and equally short. Front tibia with heterogeneous pd ciliation, the longest bristles are slightly longer than diameter of tibia, and with several ventral (or pv) bristles as long as vertical diameter of tibia. Middle femur with short and irregularly arranged av hairs half as long as vertical diameter of femur, 2-3 long pv are more twhan twice as long as vertical diameter of femur (intermixed with short hairs between them), dorsal ciliation very short. Middle tibia with a single long subbasal pv, other cilation short and fine (up to as long as diameter of tibia), rarely with several bristles (subbasal pd etc.) shorter than diameter of tibia. Hind femur (Fig. 2b) with short and fine av and pv hairs which are slightly shorter than vertical diameter of femur. Hind tibia (Fig. 2b) slightly curved, bearing a single long subbasal pv (twice as long as diameter of tibia), with a row of av bristles in apical third which are as long as diameter of tibia, and with 0-2 ad and 2-4 pd bristles which are at most 1.5 times as long as diameter of tibia, longer ad and pd situated mostly in apical part of tibia. Basitarsus of front leg slightly swollen and short haired, Tl: Mtl = 1.7-2.0, Mtl: Mtl = 3.6-4.3. Basitarsus of middle leg thin, bearing 2-4 pd bristles which are 2-3 times as long as diameter of basi tarsus, T2: Mt2 = 2.1-2.5, Mt2: Mt2 = 4.5-5.2. Basitarsus of hind leg (Fig. 2b) thin, with an irregular row of av bristles which are about three

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Fig. 2a-e: Rhamphomyia (Megacyttarus) poissoni TREHEN. - a: Dorsal genital lamella. - b: Hind leg (femur, tibia and basitarsus), anterior view. - c: Hypandrium and phallobase. - d: Hypopygium, macerated, lateral view. - e: Female wing. (a, c, d: Austria, Styria, Oberlaussa, b, e: France, Provence, Montagne d. Lure). Scale bars: a, c = 0.1 mm; b = 0.5 mm; d = 0.2 mm; e = 1 mm.

times as long as diameter of basitarsus and wih few pd bristles which are twice as long as diameter of basitarsus (beause of av and pd position, bristles seem to be shorter on figure than they in fact are), T3: Mt3 = 1.3-1.4, Mt3: Mt3 = 6.6-8.0. Wings clear, stigma brown, veins brown, vein A absent in apical part and badly distinct also in basal part. Costal bristle long, ax angle 70-80°. M2/D = 1.4-1.5, M3/Db = 2.0-2.8. Halter yellow, squama yellowish brown with pale fringes. Abdomen brown, dorsum of tergites brownish grey pruinose, venter light grey pruinose. Bristles and hairs mostly pale, large hind marginals on dorsum of tergites dark. Hind marginal bristles on sides of tergites 2--4 are 1/2-2/3 as long as segments, those on the following tergites short, opposite situation occurs on dorsum of tergites: hind marginals are short on 2--4 the tergites and longer on the following ones (the longest being those on the 7th segment). Discal hairs slightly shorter than marginals especiallyon dorsum of tergites. Terrninalia as in Fig. 2a, c, d. Length of body 4.1-5.5 mm, wing 4.1-5.5 mm. Female. Head: Eyes broadly dichoptic, facets in the upper part of eye smaller than the lower ones. Frons, face and occiput black, very light grey pruinose. Frons 0.15-0.20 mm broad above and 0.15-0.17 mm below, being 1.3-1.4 times as Ions as broad, frontal hairs subequally long as frons is broad. Face about 0.20-0.25 rnrn broad at midlength, slightly broadening below, being 1.3-1.5 times as long as broad. Ratio of antenna I segments = 15-17: 8-10: 29-32: 7-10. Labrum subequally long as head is high. Thorax similarly coloured as in male, maybe slightly lighter grey, brown mesonotal stripes slightly shorter than in male, those outside de are usually confined to pre sutural region, those between ac and de slightly exceeding sutura. Thoracic chaetotaxy and colour of hairs and bristles as in male, bristles a little shorter, both ac and de are slightly shorter than the distance betwen rows of ac and de. Legs: Coxae

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as in male. Legs brown, pruinose, mostly dark haired and bristled, proximal parts with some pale hairs intermixed. Both front and middle femora short haired. Front tibia with several pd and pv and a subbasal v bristle(s) which are up to as long as diameter of tibia. Middle tibia with 0-3 ad, av, pd and pv bristles which are up to as long as diameter of tibia. Hind femur somewhat arched dorsally, short haired. Hind tibia short haired, without any bristles, or with several badly detectable short pd. Basitarsi of all legs thin and short haired, front and midle ones with distinct relativelly long ventral spines. Tl: Mt1 = 2.0-2.3, Mt1: Mtl = 4.2-5.0, T2: Mt2 = 1.9-2.0, Mt2: Mt2 = 5.6-5.8, T3: Mt3 = 1.5-1.7, Mt3: Mt3 = 7.8-9.2. Wing (Fig. 2e) similar to male, M2/D = 1.1-1.3, M3/Db = 1.3-2.0. Abdomen brown, tergites 2-5 silvery, corresponding sternites light grey pruinose, the rest of abdomen grey pruinose. Discal hairs on sides oftergites 4-5 sparse and short (about 0.06 mm). Length of body 4.5-6.5 mm, wing 4.4-5.5 mm. Discussion: The species was briefly redescribed (as tephraea) by FREY (1954-56: 510, however, with a mistake "Vordermetatarsus ... oben mit 3-4 starken and sehr langen Borsten" - FREY described in fact basitarsus of mid le leg) and BARTAK (1982: 437). Illustration of male terminalia provided BARTAK (1982, Fig. 13d) and TREHEN (1966). COLLIN (1961: 411) stated that the type of R. tephraea MEIGEN represents in fact probably R. laevipes (FALLEN, 1816). The same synonymy was confirmed by BARTAK (1989). The same author (BARTAK 1982: 437) synonymised ,,R. tephraea: auct." with R. poissoni TREHEN. Because no younger name exists (all authors treated the species described above as R. tephraea) , it should be named R. poissoni in spite of the fact that the species was described rather by mistake (TREHEN considered R. tephraea to be a separate species of Megacyttarus and fixed differences between both "species" on the base of rather inadequate illustration by FREY (l.c.) - Fig. 393, where for example hypandrium is hairy and one hair is present even on base of phallus'). R. poissoni may be differentiated from both other species of the group according to the key. Beside characters given in the key, middle lobe of dorsal genital lamella is only moderately bent and very narrow, whereas almost right angled bent and distinctly broader in both remaining species of this group (compare Fig. 2a). The female differs from al other Palaearctic Rhamphomyia by the following combination of characters: ac bristles biserial, legs brown (not yellow), anal vein incomplete, de bristles multi serial, ax angle never sharply acute, pro sternum bare, body partly pale haired, mesonotum with dark stripes between rows of bristles, cell D short, wing clear without dark spots (contrary to R. maculipennis ZETTERSTEDT, 1842), hind femur short haired ventrally (contrary to R. fulvolanata FREY, 1922), face bare (contrary to R. brevicellula SAIGUSA, 1964). However, females of both other species of this group remain unknown.
Material examined (beside records published by BARTAK (1982, 1998) and BARTAK et al. (1997), from Germany, Italy, Switzerland, Czech and Slovak Republics): CZECH REPUBLIC (Sepekov, Jistebnice, Vnii nr, Pisek, Dobris, Horni Lomna, Sazava, Mukafov, Jistebnice), SLOVAK REPUBLIC (Nova Sedlica, Stakin, Volarensky potok), FRANCE (Montagne d. Lure, Sr. Front), HUNGARY (Misina - Mecsek), AUSTRIA (Styria - Hengstpass, Oberlaussa, Unterlaussa), 125 ex (PCMB, CUP) on dates ranging from IS.v. (SWITZERLAND: Delemont) - IS.vii. (CZECH REPUBLIC, Bohemia mer., Sepekov nr. Smutna river), CEIANU (1992) recorded even 20.vii. Distribution: Temperate Europe ranging in West-East direction from France to Romania (CEIANU 1992) and from northernmost record in south Finland to North Italy and southern France. The species seems to be common along brooks flowing through forests or meadows with well developed tree vegetation corridor. Dates of occurrence: May-June.

Rhamphomyia (Megacyttarus) tuberifemur spec. nov.
(Fig.3a-d)

Male. Head: Eyes dichoptic, facets in the upper part of eye smaller than lower ones. Frons brownish black, light grey pruinose, 0.14 mm broad above and 0.13 mm below, being 1.5 times as long as broad, bearing 4 black hairs on each side which are longer than frons is broad. Ocellar bristes much longer than frons, black, and ocellar triangle with 2-4 additional hairs. Face brownish black, light grey pruinose, 0.15 (? slightly collapsed) mm broad at midlength, broadening below, being almost twice as long as broad, bare. Occiput black, light grey pruinose, sparsely black bristled in upper part (bristles arranged almost in two rows), in lower third with pale hairs, postocular row nearly complete. Antennae black, both basal segments brown, ratio of antenna 1 segments = 16: 8: 37: 6. Labrum brown, polished, as long as head is high. Palpi brown, short, covered with a few hairs, preapical bristle slightly prominent.

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Fig. 3a-d: Rhamphomyia (Megacyttarus) tuberifemur spec. nov. (Holotype). - a: Hypopygium, macerated, lateral view. - b: Hind leg, anterior view. - c: Dorsal genital lamella. - d: Hypandrium and phallobase. Scale bars: a = 0.2 mm; b = 0.5 mm; c, d = 0.1 mm.

Thorax brownish black, light grey pruinose, mesonotum with two brown stripes between ac and dc bristles and two brown stripes outside of de, these brown markings are not very distinct. Large bristles and hairs are black, small hairs incl. mtpl pale. Chaetotaxy: 1-2 pale hairs on proepistemum, propleura and prostemum bare, 16 closely biserial (almost uniserial), fine ac are about as long as the distance between rows of ac and de, 16-21 de are irregularly biserial, medium thick and slightly longer than the distance between rows of ac and de, ending in 2-3 prescutellars, 1 long black h (and several much shorter pale hairs), 1 ih, 1 ph (1-2 hairs between ih and ph), 1 strong and 2 smaller n (a few pale hairs in front part of notopleura), 2-3 sa (3 pra hairs), 1 pa, 2 long and 2 short sc, mtpl pale. Legs: Coxae brownish black, light grey pruinose, pale haired. Legs brown, pruinose, basal part of middle femur subpolished anteriorly. Legs pale haired mostly on femora and dark haired on proximal parts. Rather long but fine bristle present in "comb" at tip of hind tibia. Front femur with av ciliation up to 2/3 as long as vertical diameter of femur, pv slightly shorter. Front tibia with pd ciliation shorter than diameter of tibia (except preapical bristles). Middle femur with short and irregularly arranged av hairs half as long as vertical diameter of femur, with a single long subbasal pv and additional 1-2 pv in apical half of femur which are 1-2 times as long as vertical diameter of femur, dorsal ciliation very short. Middle tibia with a single long subbasal pv, other cilation except preapical bristles short and fine (shorter than diameter of tibia). Hind femur (Fig. 3b) conspicuously narrowed in basal part, bearing prominent posterior tubercule slightly beyond middle, fine and sparse av hairs are at most as long as vertical diameter of its narrowed basal portion, dorsal and pv ciliation shorter. Hind tibia (Fig. 3b) distinctly curved, bearing a row of 3-4 pv in basal half of tibia which are up to 1.5 times as long as diameter of tibia, av are rather dense and slightly longer than diameter of tibia at about middle, an irregular row of dorsal bristles in apical 1/4 of tibia consists of about 15 bristles which are about 5 times as long as diameter of tibia.

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b

a

e

Fig. 4a-f: Differential characters of Rhamphomyia (Megacyttarus) spp. - a, b: Rhamphomyia (Megacyttarus) poissoni TREHEN. - a: Antennal flagellum, - b: Tip of vein Rl and part of vein R2+ 3, wing membrane microchaetae illustrated only partly. - c-f: Ejaculatory apodeme, cranial view. - c: Rhamphomyia (Megacyttarus) paradoxa WAHLBERG, 1844, - d: Rhamphomyia (Megacyttarus) poissoni TREHEN; - e: Rhamphomyia (Megacyttarus) kamtschatica FREY, 1922; - f: Rhamphomyia (Megacyttarus) crassirostris FALLEN. Scale bars: a-f= 0.1 mm.

Basitarsus of front leg slightly swollen and short haired, TI: Mtl = 1.8 (?), Mtl: Mt l = 3.5 (? basitarsi are collapsed on both sides). Basitarsus of middle leg thin and short haired, T2: Mt2 = 2.3, Mt2: Mt2 = 5.8. Basitarsus of hind leg (Fig. 3b) swollen as well as the second joint of hind tarsi, both are covered with long dorsal bristles (which are more than twice as long as their greatest diameter), ventral hairs short, T3: Mt3 = 1.8, Mt3: Mt3 = 3.9. Wings clear, stigma light brown, veins yellowish brown, vein A absent in apical part. Costal bristle present, ax angle 75°. M2/D = 1.5, M3/Db = 1.9. Halter yellow, squama brownish yellow with pale fringes. Abdomen brown, light grey pruinose. Bristles and hairs mostly pale, large hind marginals on dorsum of hind tergites dark. Hind marginal bristles on sides of tergites 2-4 are 2/3 as long as segments, those on the following tergites half as long as segment, dorsum of tergite 2 with short hind marginals, hind marginals on dorsum of tergites 3~5 subequal to those on sides and on tergites 6-7 longer than those on sides. Discal hairs shorter than marginals especially on tergites 4-7. Terminalia as in Fig 3a, c, d. Length of body 4.5 mm, wing 6.5 mm. Female: Unknown. Differential diagnosis: Rhamphomyia (Megacyttarus) tuberifemur spec. nov. is closely related to R. poissoni. Both species differ most easily in hind leg chaetotaxy as described in the key and illustrated on Figs 2b and 3b. Moreover, brown stripes on mesonotum are much less prominent in R. tuberifemur than in R. poissoni. Male genitalia differs from both other species of this group by very long and narow tip of ventral lobe of dorsal genital lamella (Fig. 3c).
Material. Holotype male: GEORGIA, Andzharia, okr. (= district) Kobuleti, Kintrishskij zapov., 10.v.1971, leg. V. KOVALEV, deposited in ZMUM. - No further specimens available. Distribution: Georgia. Dates of occurence: May. Derivatio nominis: The name of the species is derived from the prominent posterior tubercule on hind femora.

Acknowledgements
This paper was supported by grant No 206/99/0478 of Czech Grant Agency. I am very much indebted to the late Dr V. G. KOVALEV and staff of Zoological Museum, Moscow State University (Prof A. SHATALKIN, Dr A. OZEROV) for enabling me the study of valuable specimens. I thank also my wife for drawing illustrations.

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BARTAK:

Revision of the Rhamphomyia (Megacyttarus) poissoni-group (Diptera, Empididae) ..,

Literature
BARTAK, M. (1982): The Czechoslovak species of Rhamphomyia (Diptera, Empididae), with description of a new species from Central Europe. - Acta Universitatis Carolinae - Biologica 1980 (1982): 381--461; Prague. BARTAK, M. (1989): Revision of the MEIGEN'S types of Rhamphomyia (Diptera, Empididae) in the Paris Museum.Vestnik ceskoslovenske spolecnosti zoologicke 53: 1-6; Prague. BARTAK, M. (1998): Rhamphomyia (Diptera: Empididae) from the State museum of natural history, Stuttgart, with descriptions of new species. - Stuttgarter Beitrage zur Naturkunde, Serie A, 583: 26 pp.; Stuttgart. BARTAK, M. (2001): Biology of Rhamphomyia (Megacyttarus) crassirostris (FALLEN, 1816). - Acta Universitatis Carolinae - Biologica 45: 9-14; Prague. BARTAK, M. (2002): Nearctic species of Rhamphomyia subgenus Megacyttarus. - Acta Universitatis Carolinae Biologica 46: 3-215; Prague. BARTAK, M.; BEUK, P. & MERZ, B. (1997): Faunistics of the Rhamphomyia species of Switzerland (Diptera, Empididae). - Mitteilungen der Schweizerischen Entomologischen Gesellschaft 70: 335-344; Lausanne. CEIANU, I. (1992): Contribution to the knowledge of superfamily Empidoidea (Diptera) in Romania. I. - Travaux du Museum d'Histoire Naturelle "Grigore Antipa" 32: 17-48; Bucuresti. COLLIN, J. E. (1961): British Flies, Empididae. VI: 782 pp.; Cambridge. FREY, R. (1954-56): 28. Empididae. - In: LINDNER, E. (ed.): Die Fliegen der palaearktischen Region 4(4): 400-639; Stuttgart: Schweitzerbart'sche Verlagsbuchhandlung. TREHEN, P. (1966): Sur une nouvelle espece du genre Megacyttarus (Dipt. Empididae). - Annales de la Societe entomologique de France (N.S.) 2(3): 325-628; Paris.

Author's address RNDr. Miroslav BARTAK Czech University of Agriculture Faculty of Agronomy Dep. of Zoology and Fishery 165 21 Praha 6 - Suchdol Czech Republic E-mail: bartak@af.czu.cz
The paper was accepted on 10 January 2003. Editum: 15 November 2004.

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