European Journal of Taxonomy 61: 1-14

http://dx.doi.org/10.5852/ejt.2013.61

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2013 • Grichanov I.Ya.

Research article

urn:lsid:zoobank.org:pub:C47F5484-764A-41E9-8913-3CCB0092B0DF

West Palaearctic species of the genus Diosiracus Loew, 1861

(Diptera: Dolichopodidae)

Igor Ya. GRICHANOV

All-Russian Institute of Plant Protection, Podbelskogo 3, St.Petersburg, Pushkin, 196608, Russia

E-mail: [email protected]

urn:lsid:zoobank.org: author: 5320AD3A-92D8-4820-8091-24802F8C8C06

Abstract. Anew status (as subgenera of Diostracus Loew, 1861) for Sphyrotarsus Mik, 1874, Lago-

dechia Negrobov & Tsurikov, 1996 and Ozmena Ozdikmen, 2010 stat. nov. is proposed. A new species,

Diostracus ( Sphyrotarsus) kustovi sp. nov., is described from the Russian Caucasus. The following

recombinations (comb, nov.) are also proposed: Diostracus ( Sphyrotarsus) argyrostomus (Mik, 1874);

D. (S.) caucasicus (Negrobov, 1965); D. ( S.) hervebazini (Parent, 1914); D. {S.) hessei (Parent, 1914);

D. (S.) hygrophilus (Becker, 1891); D. ( S.) leucostomus (Loew, 1861); D. (S.)parenti (Hesse, 1933); D.

(Lagodechia) spinulifer Negrobov & Tsurikov, 1988; and D. ( Ozmena) stackelbergi (Negrobov, 1965).

A key to ten Diostracus species inhabiting the West Palaearctic Region is provided.

Key words. Dolichopodidae, Diostracus , West Palaearctic, new species, key.

Grichanov I.Ya. 2013. West Palaearctic species of the genus Diostracus Loew, 1861 (Diptera: Dolichopodidae).

European Journal of Taxonomy 61: 1-14. http://dx.doi.org/10.5852/eit.2013.61

Introduction

Until the 1960s the genus Diostracus Loew, 1861, belonging to the subfamily Hydrophorinae, had long

been supposed to be Nearctic in distribution, with three known species. In 1968 it was recorded from

East Asia for the first time by Talcagi (1968). To date, 85 species have been described from a vast territory

of the East Palaearctic and Orient, from Buryatia and Sakhalin in the north to Nepal, Bhutan, Assam,

NE Myanmar, Yunnan and Taiwan in the south (Grichanov 2003-2013). Negrobov (1978) placed the

genus Asphyrotarsus Oldenberg, 1916 in synonymy with Diostracus , thus recording the genus in the

West Palaearctic for the first time. In all, the Palaearctic Region is known to include 21 of the 88 known

species of Diostracus (Grichanov et al. 2011b).

The adults are usually found on wet rocks in mountainous areas or on stones in streams and waterfalls at

high altitude. A key to Palaearctic species of the genus was provided by Negrobov (1978). A key to 37

Nepalese species was given by Saigusa (1984), who proposed 12 species groups and subgroups. A key

to 14 Japanese species was given by Masunaga (2000), who mentioned some more species groups. The

last key to males of the 23 known Chinese species was published by Yang et al. (2011).

Anew species, Diostracus {Sphyrotarsus) kustovi sp. nov., from the Russian Caucasus is here described

and illustrated. The following recombinations (comb, nov.) are also proposed: Diostracus {Sphyrotarsus)

European Journal of Taxonomy 61: 1-14 (2013)

argyrostomus (Mik, 1874); D. (S .) caucasicus (Negrobov, 1965); D. (S.) hervebazini (Parent, 1914); D.

(S.) hessei (Parent, 1914); D. (S .) hygrophilus (Becker, 1891); D. (S .) leucostomus (Loew, 1861); D.

(S.) parenti (Hesse, 1933); D. ( Lagodechia ) spinulifer Negrobov & Tsurikov, 1988; and D. ( Ozmena )

stackelbergi (Negrobov, 1965). In addition, a key to males of West Palaearctic species is provided. With

the new species described here, the West Palaearctic fauna of Diostracus now totals 10 species.

Material and Methods

The holotype and paratype of the new species as well as other material examined are housed at the

Zoological Institute of the Russian Academy of Sciences, St Petersburg (ZIN).

Specimens were studied and photographed with a ZEISS Discovery V-12 stereo microscope and an

AxioCam MRc5 camera. Morphological terminology and abbreviations follow Cumming & Wood

(2009). The lengths of the podomeres are given in millimetres. Body length is measured from the base of

the antenna to the tip of abdominal segment 7. Wing length is measured from the base to the wing apex.

Male genitalia were macerated in 10% KOH. The figure showing the male genitalia in lateral view is

oriented as they appear on the intact specimen, with the morphologically ventral surface of the genitalia

facing up, dorsal surface down, anterior end facing right and posterior end facing left. Information on

world distribution for known species follows Grichanov (2003-2013).

Results

Class Hexapoda Blainville, 1816

Order Diptera Linnaeus, 1758

Suborder Brachycera Schiner, 1862

Superfamily Empidoidea Latreille, 1804

Epifamily Dolichopodoidae Latreille, 1809

Family Dolichopodidae Latreille, 1809

Subfamily Hydrophorinae Lioy, 1864

Genus Diostracus Loew, 1861

Diagnosis

The genus is very polymorphic and characterized by the following combination of characters: body

dark and stout, medium- to large-sized; palpus usually enlarged, loosely applied on proboscis; proboscis

bulky; antennal scape glabrous or setose dorsally; arista-like stylus usually dorsal, sometimes basodorsal

or subapical to apical; posterior mesonotum flattened; acrostichal setae absent; 4-6 dorsocentral bristles

variable in length; sutural and postsutural, some notopleural, supra-alar and post-alar bristles sometimes

absent or reduced; scutellum with 1-2 pairs of strong bristles and with some short lateral setae or hairs,

sometimes with three pairs of long bristles; mid and hind coxae without bristle on the outer side; legs

often modified; tarsi with more or less modified empodium and claws, usually without pulvilli; wing

elongate and wide, sometimes modified in males; costa ended beyond tip of wing; crossvein dm-cu

longer than distal section of CuA ] vein, sometimes strongly sinuate; M 1+0 usually slightly convex

anteriorly, often irregularly curved, more or less parallel to R 4+5 , at least partly behind dm-cu.

Remarks

The genus Sphyrotarsus Mik, 1874 includes 5 species from the European Alps, one Caucasian species

and one Pamiran species. It was diagnosed by scape glabrous dorsally; tarsi with reduced empodium

and without pulvilli; M |+0 and R 4+5 are not strictly parallel to each other (Parent 1938); scutellum with

GRICHANOVI. Ya., West Palaearctic species of Diostracus

3 pairs of bristles (Negrobov 1978). Furthermore, the Pamiran subgenus Takagia Negrobov, 1973 (of

Sphyrotarsus), was diagnosed by elongated antennal postpedicel with arista apical, somewhat widened

at apex in male; sutural bristle absent; one supra-alar bristle; scutellum with 2 pairs of bristles (Negrobov

1973, 1978). Nevertheless, all these characters are rather variable and can be found in East Asian species

of Diostracus. The monotypic Caucasian genus Lagodechia Negrobov & Tsurikov, 1996 was diagnosed

also by variable characters of face, mesonotal setation, wing venation and morphology of abdomen

(Negrobov & Tsurikov 1996). In addition, some characters of L. spinulifera were incorrectly described,

as follows from the illustrations published by Grichanov et al. (2011 a, b). I think the diagnostic characters

of these taxa have low generic significance and regard Lagodechia, Sphyrotarsus and Takagia (now

Ozmena Ozdikmen, 2010) as subgenera of Diostracus. Accepting a new concept of the genus, I associate

97 species with Diostracus, of which 64 occur in the Oriental Region, 30 in the Palaearctic and 3 in the

Nearctic Region. The flies of the genus are all torrenticolous in habitat.

Subgenus Diostracus Toew, 1861

Diostracus Loew, 1861a: 43; Takagi 1968: 35 (diagnosis), 51 (redescription of type species). —

Grichanov et al. 2011b: 22 (diagnosis).

Asphyrotarsus Oldenberg, 1916: 193. —Negrobov 1978: 406 (synonym of Diostracus Loew, 1861). —

Type species: Liancalus leucostomus Loew, 1861 (original designation).

Diagnosis

At present the nominotypical subgenus differs from other subgenera in having a dorsally setose antennal

scape. It is worth noting that many Asian Diostracus species were described with a glabrous scape (e.g.,

Saigusa 1984, 1995; Saigusa et al. 1997; Yang et al. 2011).

Type species

Diostracus pr as inns Loew, 1861 (by monotypy).

Diostracus ( Diostracus ) leucostomus (Loew, 1861)

Liancalus leucostomus Loew, 1861b: 348.

Thinophilus nigripes Strobl, 1898: 219. — Negrobov 1973: 1518 (synonym of Asphyrotarsus

leucostomus, redescription of type). — Type locality: Styria, Sirbitzlcogel, Austria.

Asphyrotarsus leucostomus - Oldenberg 1916: 193. —Parent 1938: 312.

Diostracus leucostomus - Negrobov 1978: 411.

Diostracus nigripes - Negrobov 1978: 411.

Type locality

Karnthen, Austria.

Distribution

Austria, France, Italy, Switzerland.

Subgenus Lagodechia Negrobov & Tsurikov, 1996, stat. nov.

Lagodechia Negrobov & Tsurikov [as Zurikov], 1996: 632. — Grichanov et al. 2011b: 23 (diagnosis).

European Journal of Taxonomy 61: 1-14 (2013)

Diagnosis

Describing a new genus, Negrobov & Tsurikov (1996) listed diagnostic characters that can be found in

many Diostracus species (e.g., Saigusa 1984, 1995; Saigusa etal. 1997; Yang etal. 2011). The following

characters of generic importance were listed in the original description of Lagodechia , but were not

obvious on pictures made by O. Selivanova from type material (Grichanov et al. 2011a, b): antennal

scape has dorsal projection; distance between scutellum and 1 st tergum is 3 times as long as scutellum.

Negrobov & Tsurikov (1996) also found important differences in the female oviscapt of Lagodechia

spinulifera and Diostracus subalpinus (Negrobov, 1973). Unfortunately, D. subalpinus (described from

the Baikal Take environs) is the only Diostracus species with illustrated female genitalia. The status of

D. subalpinus and D. spinulifer needs further clarification.

Type species

Diostracus spinulifer Negrobov & Tsurikov, 1988 (original designation).

Diostracus (Lagodechia) spinulifer Negrobov & Tsurikov, 1988, comb. nov.

Diostracus spinulifer Negrobov & Tsurikov [as Zuricov] in Negrobov et al ., 1988: 215.

Lagodechia spinulifer- Negrobov & Tsurikov 1996: 632.

Type locality

Lagodekhis-Khevi river, upper stream, Tagodekhi Reserve, Georgia.

Distribution

Georgia.

Subgenus Ozmena Ozdikmen, 2010, stat. nov.

Ozmena Ozdikmen, 2010: 265 (new name for Takagia Negrobov, 1973, not Matsumura, 1942) (as

subgenus of Sphyrotarsus Mik, 1874).

Takagia Negrobov, 1973: 1520 (as subgenus of Sphyrotarsus Mik, 1874) (not Matsumura, 1942). —

Negrobov 1978: pi. CTXI (as genus, in error). — Type species: Sphyrotarsus stackelbergi Negrobov,

1965 (original designation).

Diagnosis

The main diagnostic character of the subgenus is the elongate antennal postpedicel in both male and

female, and the apical stylus (Negrobov 1973). Nevertheless, some Oriental Diostracus species also

have an elongate postpedicel and an apical or subapical stylus (e.g., Saigusa 1984; Yang et al. 2011).

Unfortunately, there are practically no publications with pictures of female antennae in Diostracus

species.

Type species

Sphyrotarsus stackelbergi Negrobov, 1965 (by monotypy).

Diostracus (Ozmena) stackelbergi (Negrobov, 1965), comb. nov.

Sphyrotarsus stackelbergi Negrobov, 1965: 441.

Sphyrotarsus ( Takagia ) stackelbergi - Negrobov 1978: 405.

Sphyrotarsus ( Ozmena ) stackelbergi - Ozdikmen 2010: 265.

GRICHANOVI. Ya., West Palaearctic species of Diostracus

Type locality

Gorno-Badakhshan region, Khorog, river Gunt, Shugnan, Tajikistan.

Distribution

Tajikistan (Pamir).

Subgenus Sphyrotarsus Mik, 1874, stat. nov.

Sphyrotarsus Mik, 1874: 342. — Grichanov et al. 2011b: 25 (diagnosis).

Diagnosis

As presently defined, the subgenus differs from other subgenera in the presence of 6 (vs. 2—4) long

bristles on the scutellum in addition to the glabrous antennal scape (Negrobov 1973; Grichanov et al.

2011b). These characters are rather variable in Asian Diostracus species (e.g., Saigusa 1984, 1995;

Saigusa et al. 1997; Yang et al. 2011). Parent (1938) also used variable male secondary sexual characters

to distinguish Sphyrotarsus from Asphyrotarsus ( =Diostracus).

Type species

Sphyrotarsus argyrostomus Mik, 1874 (by monotypy).

Diostracus {Sphyrotarsus) argyrostomus (Mik, 1874), comb. nov.

Sphyrotarsus argyrostomus Mik, 1874: 337. —Parent 1938: 298.

Sphyrotarsus (* Sphyrotarsus ) argyrostomus - Negrobov 1978: 402.

Type locality

Wildbadgastein, Austria.

Distribution

Austria, France, Italy, Switzerland.

Diostracus {Sphyrotarsus) caucasicus (Negrobov, 1965), comb. nov.

Sphyrotarsus caucasicus Negrobov, 1965: 440.

Sphyrotarsus {Sphyrotarsus) caucasicus - Negrobov 1978: 403.

Material

\S, Adygea, Maikop distr., Caucasian Nature Reserve, Abago Mt, alpine belt, sweeping on grass at

snowfield rivulet, 2100 m, 4 Aug. 2008, Volfov (ZIN).

Type locality

Caucasian Reserve, Cherkesskii Ridge, Russia.

Distribution

Russia (Adygea, Krasnodar).

European Journal of Taxonomy 61: 1-14 (2013)

Diostracus ( Sphyrotarsus ) hervebazini (Parent, 1914), comb. nov.

Sphyrotarsus hervebazini ¥ went, 1914: 85; 1938: 300.

Sphyrotarsus (, Sphyrotarsus) hervebazini - Negrobov 1978: 403.

Sphryotarsus (Sphyrotarsus) hervibazini - Negrobov 1991: 42 (error for hervebazini).

Type locality

Saint-Pierre-de-Chartreuse, Isere, France.

Distribution

France, Switzerland.

Diostracus (Sphyrotarsus) hessei (Parent, 1914), comb. nov.

Sphyrotarsus hesseiFarent, 1914: 108; 1938: 301.

Sphyrotarsus (Sphyrotarsus) hessei - Negrobov 1978: 403.

Type locality

Arras, France.

Distribution

France, Italy.

Diostracus (Sphyrotarsus) hygrophilus (Becker, 1891), comb. nov.

Sphyrotarsus hygrophilus Becker, 1891: 286. —Parent 1938: 303.

Sphyrotarsus (Sphyrotarsus) hygrophilus - Negrobov 1978: 404.

Sphyrotarsus (Sphyrotarsus) hydro phi Ins - Negrobov 1978: 404 (error for hygrophilus).

Type locality

Gesause bei Admont, Austria.

Distribution

Austria, France, Switzerland.

Diostracus (Sphyrotarsus) parenti (Hesse, 1933), comb. nov.

Sphyrotarsus parenti Hesse, 1933: IF —Parent 1938: 305.

Sphyrotarsus (Sphyrotarsus) parenti - Negrobov 1978: 405.

Type locality

Col du Lautaret, France.

Distribution

France.

GRICHANOVI. Ya., West Palaearctic species of Diostracus

Diostracus (Sphyrotcirsus) kustovi sp. nov.

(Figs 1A-E, 2, 3A, B)

urn:lsid:zoobank.org:act:C06CA79F-16D5-45ED-8309-8BCD4613E37C

Diagnosis

Scutellum with 3 pairs of almost equally long bristles; antennal scape bare above; male and female

postpedicel about as long as high, with dorsal stylus; male 2 nd and 3 rd abdominal sterna with strong black

spines; male 4 th abdominal sternum with bundle of setae; male with modified legs and simple wings.

Etymology

This species is named after the Russian dipterologist Dr. Semyon Kustov (Krasnodar).

Type material

Holotype

RUSSIA: S, Karachai-Cherkessia, Arkhyz env., Sofiiskie waterfalls, 43 o 26’09” N, 41 o 16’03” E, 2400

m, 03 Aug. 2012, S. Kustov (ZIN).

Paratype

RUSSIA: 1$, same data as for holotype (ZIN).

Description

Male

Length (mm). Body 9.4, wing 7.8, antenna 1.5, hypopygium 2.25.

Head (Figs 1A, B). Bluish-greenish black, pollinose; clypeus shining green, weakly pollinose, 1/3 as

wide as head; face about 1/5 as wide as head, almost as long as wide; ocellar bristles strong, vertical and

postvertical bristles about 1/2 as long as ocellar bristle; postocular ciliation black, strong, nearly as long

as postvertical on upper 1/2, finer and yellowish below; ventral 1/2 of postcranium clothed with many

long yellow hairs, some of which as thick as vertical bristle; antenna with bare vase-like scape; pedicel

with ring of short setae; postpedicel as long as high, rounded distally, with middorsal simple arista-like

stylus; length (mm) of scape to pedicel to postpedicel to stylus (1 st and 2 nd segments), 0.16-0.11-0.2-

0.13-0.85; palpus ovate, 1.6 times as long as wide, 1/3 as long as eye height, slightly dilated at middle;

palpus black in ground colour, glittering silvery by pollinosity, bearing short black setae on outer side

and along margin; proboscis moderately large for the genus.

Thorax. Greenish black, with washed pollinosity; mesonotum with pair of blackish longitudinal

stripes; acrostichals absent; 5-6 asymmetrical dorsocentrals; 1 humeral with 1-2 short setae in front, 1

posthumeral, 2 notopleurals, 1 sutural, 1 postsutural, 1 supra-alar, 1 postalar; scutellum with 3 pairs of

strong scutellars, of which outer pair 2/3 length of median 4 bristles; proepistemum with about 10 yellow

setae on its lower portion and with about 6 similar seta on its upper portion; scutellum about 3 times

wider than long; postscutellum about 3 times as long as scutellum (similar to that in D. leucostomus).

Legs. Rather long, black with slight greenish or bluish tinge on coxae and femora; fore coxa concave on

anterior surface towards tip, there clothed with short, fine hairs, also with row of short, black, blunt setae on

anterodistal margin; fore femur moderately thick, strongly curved at basal 1/3, with very short, fine hairs;

fore tibia slightly thickened, bearing 4 dorsal bristles, 2 posterodorsals at base, 1 long curled posterodorsal

bristle at apex, 1/3 as long as tibia, and with double row of short, erect ventral setae; fore basitarsus (Fig.

1C) constricted and almost bare in 1 st quarter, thickened in 2 nd quarter, densely short setose; its thickening

European Journal of Taxonomy 61: 1-14 (2013)

bearing 3 long, curled dorsal bristles, half as long as basitarsus, and row of 12 short blunt spinules; 2 nd to 4 th

tarsomeres simple, bearing elongate setae dorsally; 4 th tarsomere with strong apicoventral seta; 5 th segment

flattened dorsoventrally; pulvillus reduced, empodium spicular, claws strong, about half as long as 5 th

segment; mid coxa covered with short fine white hairs anteriorly, bearing 3M strong apical dirty yellow

bristles forming some kind of spine; mid femur (Fig. ID) slightly curved, distinctly emarginated dorsally

along basal half or more, with rather long yellow hairs and setae on anterior, dorsal and ventral surfaces

Fig. 1 . Diostracus ( Sphyrotarsus ) kustovi sp. nov. Male holotype. A. Head in anterior view. B. Head in

lateral view. C. Fore tarsus. D. Mid leg. E. Hind tibia in apical view and basitarsus.

GRICHANOVI. Ya., West Palaearctic species of Diostracus

of its basal 1/2, the vestiture slightly darker on dorsal surface; the longest setae twice as long as femur

diameter; apical 1/2 of mid femur almost bare and bearing 2-3 anteroventral and 2-3 posteroventral short

bristles; mid tibia straight, subapically thickened, short setose, with several anterodorsal and posterodorsal

bristles and subapical ventral fringe of strong black bristles longer than tibia thickness; mid tarsus slender,

simple and short setose, with reduced pulvillus and empodium; hind coxa bearing sparse short, yellow

hairs outside; hind femur long and simple, only slightly curved, with about 6 fine anteroventral black

setae in distal 1/2, not longer than femur diameter, with long, fine, subapical anterior bristle; hind tibia

slender, bearing several longish bristles on anterodorsal and posterodorsal surfaces and shorter ones on

anteroventral and posteroventral surfaces, with about 5 long blackish-brown apicoventral bristles, of

which longest bristle reaching middle of basitarsus; hind basitarsus (Fig. IE) slightly swollen at base,

with 4 short dorsal setae, with about 10 long blackish and brownish fine bristles at base ventrally and

anteriorly, longest seta more than half as long as basitarsus; next tarsomeres slender and simple; pulvillus

and empodium reduced. Fore podomere length (from femur to tarsomere 5, mm): 1.77-1.96-1.37-0.40-

0.27-0.18-0.29 (0.45 with claws); mid leg: 2.86-2.95-1.65-0.54-0.33-0.23-0.33 (0.49 with claws); hind

leg: 3.00-3.52-1.38-0.72-0.43-0.25-0.29 (0.40 with claws).

Fig. 2. Diostracus ( Sphyrotarsus ) kustovi sp. nov. Male holotype. Abdominal segments 2 and 3.

European Journal of Taxonomy 61: 1-14 (2013)

Fig. 3. Diostracus ( Sphyrotarsus ) kustovi sp. nov. Male holotype. A. Apex of abdomen and hypopygium.

B. Hypopygium. Abbreviations: cer - cercus, ep - epandrium, hyp - hypandrium, ph - phallus, sur -

surstylus.

GRICHANOVI. Ya., West Palaearctic species of Diostracus

Wing. Simple, almost hyaline, with simple veins; Sc developed; R 2+3 and R 4+5 weakly convex anteriorly;

R 4+5 and M 1+9 almost straight and parallel behind level of dm-cu; M 1+9 weakly sinuate; ratio of part of

costa between R 0+3 and R 4+5 to that between R 4+5 and M 1+0 = 73/57; ratio of cross-vein dm-cu to distal

part of CuAj = 84/47; dm-cu perpendicular to both longitudinal veins; calypter blackish, with pale cilia;

halter orange yellow.

Abdomen. Black, with washed pollinosity, with short black setae; 1 st tergum with long brownish setae

and ciliated with long black bristles on posterior margin; 1 st sternum projected, with shallow transverse

furrow anteriorly; 2 nd sternum (Fig. 2) with medial bulb at anterior 1/3, bearing 2 adjacent black spines

formed of long glued setae and directed anteriorly; 3 rd sternum (Fig. 2) with twice as large bulb bearing

2 diverging black spines formed of long glued setae and directed anteriorly; 4 th sternum (Fig. 3 A) with 2

median bunches of erect brownish setae on low convection, with posterior margin somewhat projecting

and covered with short hairs; hypopygium (Fig. 3B) black, moderately large, with posterodorsal portion

moderately produced and rounded; hypandrium subtriangular, narrow distally and bifurcated at apex;

phallus simple; epandrial lobe short and narrow; surstylus brown, almost semicircular, with short hairs

dorsally; cercus distinctly longer than epandrium, slightly swollen at base, band-like, simple, densely

ciliated with long yellow setae.

Female

Length ( mm ) Body 7.0, wing 8.0, antenna 1.4.

Similar to male except lacking male secondary sexual characters, otherwise as follows: 6 dorsocentrals

of irregular length in left row and 8 dorsocentrals in right row; palpus not glittering silvery; legs and

abdominal sterna simple; 6 th and 5 th terga and genital plates densely covered with fine long setae; no

acanthophorites.

Remarks

Having bulbs on 2nd and 3rd sterna and bearing strong ventral spines or bunches on abdomen, the

new species distinctly differs from other species of the subgenus Sphyrotarsus (see key below). D.

(L.) spinulifer males also have a setose venter, but not bearing bulbs and thick spines. Some Chinese

and Nepalese species of Diostracus were also described with male sterna ornamented with bunches of

setae, spines or projections (e.g., Saigusa 1984; Yang et al. 2011), but strongly differing in many other

characters.

Ecology

Both types of D. (S.) kustovi were collected together on stones at a stream (S. Kustov, pers. comm.) in

high mountains at 2400 m above sea level.

Key to West Palaearctic species of the genus Diostracus (males)

Note: Partially based on previous keys to species of the former genus Sphyrotarsus (Parent 1938;

Negrobov 1978).

1. Scutellum with 1-2 pairs of long bristles and with some short lateral setae or hairs .2

Scutellum with 3 pairs of almost equally long bristles (subgenus Sphyrotarsus) .4

2. Scape with hairs above; 4.5-5.1 mm. D. ( Diostracus ) leucostomus (Loew, 1861)

- Scape bare above.3

European Journal of Taxonomy 61: 1-14 (2013)

3. Male and female postpedicel elongate-ovate, 1.5-2 times longer than high, with apical stylus;

male abdominal sternites without strong spines; body 5 mm long .

. D. ( Takagia ) stackelbergi (Negrobov, 1965)

Postpedicel about as long as high, with dorsal stylus; male 2 nd to 4 th abdominal sternites with strong

black spines; body 5-6.5 mm long. D. ( Lagodechia) spinulifer Negrobov & Zurikov, 1988

4. Male 2 nd and 3 rd abdominal sternites with strong black spines; body 7.0 mm (female) to 9.4

mm (male) long . D. (S.) kustovi sp. nov.

- Male abdominal sternites without strong spines .5

5. Male cercus shorter than epandrium; body 6 mm long. D. (5.) caucasicus (Negrobov, 1965)

- Male cercus longer than epandrium.6

6. All tarsi with empodium scaly in male, as long as claws; mid basitarsus thin, longer than rest

of tarsomeres combined; body 6.5 mm long. D. (S.) hygrophilus (Becker, 1891)

Tarsi with reduced empodium; mid basitarsus shorter than rest of tarsomeres combined .7

7. Male cercus bifurcated between base and middle; mid basitarsus thickened at middle and at

apex .8

- Male cercus bifurcated at apex only; mid basitarsus simple or thickened at base .9

8. Outer arm of cercus long and narrow; body 5.2-6 mm long. D. (A) argyrostomus (Mik, 1874)

Outer arm of cercus short, broad, subtriangular; body 7 mm long. D. (S.) parenti (Hesse, 1933)

9. Palpus bare; proboscis as long as head; body 5.2 long. D. (S.) hessei (Parent, 1914)

- Palpus covered with black hairs; proboscis half as long as head; body 6-6.5 mm long.

. D. (S.) hervebazini (Parent, 1914)

Discussion

The subgenera of the genus Diostracus are relatively well defined in the West Palaearctic Region. In

the Nearctic, D. mchughi Harmston, 1966 differs from D. prasinus and D. olga Aldrich, 1911 in its

bare antennal scape and can be associated with the subgenus Sphyrotarsus , although bearing only two,

rather than three pairs of long setae on the scutellum. The borders of the West Palaearctic subgenera

become rather obscure in the East Palaearctic and Orient. Saigusa (1984) supposed that most of the

species groups proposed in his paper could be raised to the subgeneric rank if a phylogenetic analysis

based on all known species were to be carried out. They could have a common ancestor, which is close

to Diostracus or Sphyrotarsus , and their real degree of separation (or similarity) may require molecular

investigation. Increased sampling effort should provide specimens that are appropriate for future studies

of these flies.

Regarding the new species described here, it seems that D. (S.) kustovi sp. nov. is one of the largest

hydrophorine species in the Palaearctic Region (see Negrobov 1977-1979). The male body is somewhat

longer than the female body (9.4 vs. 7.0 mm), while wings are approximately equal in length in the two

sexes (about 8 mm).

Acknowledgments

The author expresses sincere gratitude to Drs. E.P Nartshuk and L.A. Kuznetsova (ZIN) for their kind¬

ness in furnishing an opportunity to study the collections of their museum. This work was partly supported

by grant N 11-04-01051-a from the Russian Foundation for Basic Research to Oleg P. Negrobov.

GRICHANOVI. Ya., West Palaearctic species of Diostracus

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Manuscript received: 28 March 2013

Manuscript accepted: 5 August 2013

Published on: 30 October 2013

Topic editor: Koen Martens

Desk editor: Danny Eibye-Jacobsen

Printed versions of all papers are also deposited in the libraries of the institutes that are members of

the EJT consortium: Museum National d’Histoire Naturelle, Paris, France; National Botanic Garden

of Belgium, Meise, Belgium; Royal Museum for Central Africa, Tervuren, Belgium; National History

Museum, London, United Kingdom; Royal Belgian Institute of Natural Sciences, Brussels, Belgium;

Natural History Museum of Denmark, Copenhagen, De nm ark