A review of the genus Zavrelia ( Diptera : Chironomidae )

In this paper we review the taxonomy of the genus Zavrelia Kieffer, Thienemann & Bause and present emended generic diagnoses of all major life stages. Illustrated keys to larvae, pupae, adult males and females are presented as well as descriptions of four species new to science. Zavrelia species are only recorded from the northern hemisphere and comprise in total ten small to minute species. The following life stages and species are described: Larva, pupa, adult male and adult female of Zavrelia aristata sp. n., Zavrelia hudsoni sp. n., Zavrelia pentatoma Kieffer & Bause and Zavrelia sinica sp. n.; pupa and adult male of Zavrelia casasi sp. n.; and adult males of Zavrelia clinovolsella Guo & Wang and Zavrelia tusimatijea (Sasa & Suzuki). Zavrelia atrofasciata Kieffer and Stempellina paludosa Goetghebuer are proposed as new junior synonyms of Zavrelia pentatoma and lectotypes of Zavrelia nigritula, Zavrelia pentatoma and Stempellina paludosa are designated.


INTRODUCTION
Species of the genus Zavrelia Kieffer, Thienemann & Bause in Bause (1913) are small to minute chironomids (non-biting midges), which are recorded from both continents of the northern hemisphere.Zavrelia species seem to be less common than species of their presumed sister genus Stempellinella, but when encountered, the larvae and pupae of Zavrelia are normally found in unpolluted streams and rivers.One exception is the western Palaearctic species Zavrelia pentatoma which is so far only recorded from standing waters rich in humic acids on or near moors.All known larvae of Zavrelia species construct small, straight transportable cases of sand, silt, detritus and sometimes diatoms that function as retreats until the mature pupa swims to the surface prior to adult emergence.
The argument for the erection of the genus Zavrelia was presented in part as personal communication from Kieffer (Bause, 1913, p. 100), but since the genus is defined by both larval and pupal characters in the identification key provided in the same work (op. cit. p. 42-45 & p. 89-93), the authorship of the genus must also be credited to Bause.In addition, a footnote in the final chapter (p.118) states that Thienemann must be regarded as author of the presented classification in which the diagnostic characters are commented on.Thus, we agree with Spies (2005) that Kieffer, Thienemann and Bause all must be credited with the authorship of Zavrelia.
Until recently, there were few Zavrelia species known to science.The Catalogue of Palaearctic Diptera (Ashe & Cranston, 1990) and the later Manual of Palaearctic Diptera (Saether et al., 2000) both list three valid species from the Palaearctic region.One of these, Zavrelia kibunensis Tokunaga, 1938, was transferred to the genus Neozavrelia (Ekrem, 2006), and Zavrelia atrofasciata is below regarded as a junior synonym of Z. pentatoma.In addition, Zavrelia inopinata Botnariuc & Cindea-Cure, 1954, listed as doubtful species in the Palaearctic catalogue, is regarded as a junior synonym of Stempellinella ciliaris Goetghebuer, 1944by Ekrem (2007).At least one Zavrelia species was recognised previously in the Nearctic, but none have been described formally and named from this region yet (Epler, 2001;Oliver et al., 1990).Regarding the Afrotropical region, Kieffer (1923) described Zavrelia kribiensis from southern Africa and Cameroon and the species was maintained by Freeman (1958).However, Z. kribiensis is morphologically quite different from other Zavrelia species in all life stages and was placed in a new genus Afrozavrelia by Harrison (2004).The Catalogue of the Diptera of the Oriental Region (Sublette & Sublette, 1973) lists one unnamed species from Java reported by Zav el (1934), but not described so it is not possible to say if it is a Zavrelia or a member of the more widely distributed genus Stempellinella.
More recently, Tanytarsus tusimatijeus Sasa & Suzuki, 1999 was described from Tsushima Island (Sasa & Suzuki, 1999) and transferred to Zavrelia by Ekrem (2006).In addition, two new species of Zavrelia were described from China (Guo & Wang, 2004, 2007) and another two from Russia (Zorina, 2008).Including the four species new to science described below, the genus Zavrelia now contains a total of ten species.
Systematically, the genus Zavrelia is placed within the subtribe Zavreliina of the tribe Tanytarsini in the subfamily Chironominae (Ekrem & Saether, 2000;Saether & Roque, 2004).Morphologically, the genus is similar to its presumed sister genus Stempellinella, particularly in the immature stages.Some characters in particular seem to be useful for separating the two genera (see Ekrem, 2007, Table II, p. 1374), although examination of more associated Zavrelia pupae has revealed that not all species have shagreen on pleura II and that it is not necessarily arranged in distinct rows (this character was erroneously listed under Stempellinella by Ekrem, 2007).Preliminary phylogenetic analyses based on two nuclear and three mitochondrial markers indicate that the two genera are indeed separate monophyletic groups and thus should be maintained as entities at the same taxonomic level (Ekrem, in prep.).
The main aim of this study was to revise and describe known and previously unknown species in the genus Zavrelia and present identification keys to all major life stages as well as an emended diagnosis of the genus.

MATERIAL AND METHODS
We did some field work in Germany to supplement material on loan from collections and colleagues in Europe, North America and Asia.
Measurements are given as ranges, followed by the mean with the number of observed specimens in parenthesis if different from the number included in the description.Measurement methods follow Soponis (1977).The antennal ratio (AR) is measured on 10 flagellomeres.The lengths of the male genital volsellae were measured along their median margin, and of the anal point from the anterior ends of the anal crests to the anal point apex.In the larvae, the antennal pedestal length was measured along the median pedestal margin, excluding spur; antennal segments were measured from their base to the non-sclerotized apex, Lauterborn organs and pedicels were measured separately.All described larvae are fourth instar.
Collections (with abbreviations used in the text) in which material is deposited: CNC -Canadian National Collections, Ottawa, Ontario, Canada; NSMT -National Science Museum, Tokyo, Japan; NKUM -College of Life Science, Nankai University, Tianjin, China; PLH -Private collection of Pat L. Hudson, Ann Arbor, Michigan, USA; IRSNB -Royal Belgian Institute of Natural Sciences, Brussels, Belgium; UMSP -University of Minnesota, St. Paul, Minnesota, USA; USNM -National Museum of Natural History (Smithsonian Institution), Washington, DC, USA; NTNU -Museum of Natural History and Archaeology, Norwegian University of Science and Technology, Trondheim, Norway; WG -Wojciech Gi ka, University of Gda sk, Poland; MZH -Zoological Museum, University of Helsinki, Finland; ZSM -Zoologische Staatssammlung München, Munich, Germany.

Imago
Small species, wing length about 0.8-1.5 mm.Body with ground colour green or light brown or brown to black; vittae distinct if ground colour light.
Head.Eye hairy, without dorsomedian extension; frontal tubercles small to well developed; palp normally developed.
Wing.Membrane with setae in all cells except anterior to vein M; all veins with setae except M and Sc.Costa not produced; R4+5 ending proximal to apex of M3+4; anal lobe not developed; squama bare.Female with slightly more setae on wing compared to male, but M, Sc and cells anterior to M bare.
Legs.Apex of fore tibia with short, slender spur.Combs of mid and hind tibiae small, both bearing spurs, often one long and one short.Sensilla chaetica apparently absent from all tarsomeres.Pulvilli absent.
Male hypopygium.Anal tergite bands at least partially encircling several long median tergite setae placed at distance from anal point base, or median setae absent; laterosternite IX usually with seta.Anal point well developed, tapering distally, with long or short anal crests, extending onto anal tergite, with or without spinules and/or microtrichia in between.Setiger of superior volsella short, flattened, with digitiform or acute, medially directed tip; with 2 robust setae on distal inner margin; digitus absent.Median volsella very short, with distal clump of several long, slightly curved, setiform and lamelliform lamellae.Inferior volsella well developed, extending beyond base of gonostylus, sometimes nearly reaching apex of gonostylus, with few robust, curved setae distally, microtrichia absent at least dorsolaterally, basal wart absent.Gonostylus short, without apical tooth.
Female genitalia.Tergite IX semicircular.Sternite VIII with 20-35 setae.Gonocoxapodeme VIII strong, often with large anterior and posterior lobes.Sternite VIII sometimes forming narrow rim along lateral sides of vagina, floor absent.Gonapophysis VIII simple, with relatively long, posteromedially directed microtrichia.Apodeme lobe not apparent.Notum short or long, often as long as or slightly longer than width of seminal capsules; rami slightly diverging.Gonocoxite IX small, with few setae.Postgenital plate triangular, wide at base.Cercus can be as long as width of seminal capsules, but is usually shorter.Two seminal capsules present, almost circular, with small to large neck.Spermathecal ducts of variable length.

Pupa
Small, 2-3 mm long.Cephalothorax and lateral margins of segments VII-VIII of pupal exuviae light brown.
Abdomen.Tergite I without microspinules or shagreen; TII-VI extensively covered with fine microspinules, which are partially or completely separated by bare median patch; microspinule patch on TII starting at or anterior to seta D1.TVII and VIII and anal lobe with lateral patches of fine spinules and shagreen.Conjunctives bare; pleura of segments IV-V always with shagreen, often also pleura of segments II, III and/or VI with shagreen.Hook row continuous, covering about 1/3 of width of segment.Pedes spurii A present on segment IV; pedes spurii B on segment II well developed, rounded.Sternite I without anterolateral or anteromedian tubercles.Sternites without conspicuous armature.Segment VIII with single or sometimes bifurcate dark, posterolateral spur.Abdominal lateral setation variable: Segment II with 3 fine setae; III usually with 3 taeniate setae or 3 fine setae; IV with 3 taeniate setae or 2-3 fine setae and 0-1 taeniate seta; V with 3 or 4 taeniate setae; VI-VII each with 4 taeniate setae; VIII with 3 or 4 taeniate setae.Anal lobes moderately well developed, with complete fringe of 15-25 taeniate setae in single row and one dorsal seta on lobe.

Larva
Small, 2-2.5 mm long, case c. 2.5-3 mm long.Head.Antenna 5-segmented, placed on tall pedestal with strong distal spur; basal segment about as long as flagellum or shorter, with ring organ and short seta basally.Antennal blade extending beyond antennal apex; segment 2 longer than more distal segments, bearing style and alternate Lauterborn organs.Lauterborn organs large, bulbous, one arising in proximal half or middle of segment 2, other apically, both placed on short pedicels, distal pedicel often slightly longer.Labral seta SI and chaetae pectinate, bases fused; SII pectinate or slightly plumose, placed on tall pedestal.Chaetulae and clypeal seta S3 simple or split in several branches; SIV present.Labral lamella well developed.Pecten epipharyngis consisting of 3 small chaetae and a broad anterior scale.Premandible with 4 teeth and well developed brush; teeth almost at right angles to main axis of premandible.Mandible with dorsal tooth, apical tooth and 3 inner teeth, all pale brown.Seta subdentalis long, slender, reaching well beyond tip of mandible.Seta interna consisting of 4 plumose branches.Pecten mandibularis with moderately long lamellae; mola with 1-2 spines.Mentum with pale brown teeth medially, slightly darker laterally, or uniformly pale brown.Median tooth rounded; with 6 pairs of lateral teeth, regularly slightly decreasing in size laterally.
Ventromental plates fan-shaped, separated medially by width of the median 5 mental teeth, not as wide as mentum.Postoccipital plate well developed, continuous.
Body.Anterior parapods with simple spines; posterior parapods with 16-18 simple claws.Two pairs of anal tubules.Supraanal seta well developed.Procercus with 2 small and 4 long anal setae, the short setae situated individually and not on the common base of the long setae.

Diagnostic characters
Zavrelia species can be separated from other genera in the tribe Tanytarsini by the following characters.
Male imago: Eye hairy, without dorsomedian elongation; antenna with 10 flagellomeres; wing hairy, with costa ending proximal to tip of vein M3+4; subcosta bare; combs of mid and hind tibia separate, both bearing spur; hypopygium with anal tergite setae placed at distance from anal point base, median volsella short and stout with rosette of subulate and simple lamellae.
Female imago: Eye hairy, without dorsomedian elongation; antenna with 5 flagellomeres; wing hairy, with costa ending proximal to tip of vein M3+4; subcosta bare; combs of mid and hind tibia separate, both bearing spur; genitalia without floor under vagina, gonapophyses VIII undivided.
Pupa: Frontal seta long, taeniate; thoracic horn elongate, tapered, with small chaetae; tergites II-VI with extensive fields of microspinules and shagreen, patches on tergite II starting anterior to seta D1; segments V-VIII and usually segment IV with taeniate lateral setae; pedes spurii A and B present; segment VIII with single or occasionally bifurcate posterolateral spur.
Larva: Antennal pedestal with single apical spur; antenna with alternate Lauterborn organs on antennal segment 2; premandible with 4 teeth; ventromental plates separated by at least the width of 3 median mental teeth; postoccipital plate well developed, continuous.

Diagnostic characters
Zavrelia aristata can be separated from other Zavrelia species by the following combination of characters.Length of adult male c. 1.6 mm; AR about 0.9; frontal tubercle small, conical; anal point without spinules but with numerous microtrichiae between long, high crests; 6-11 strong median tergite setae placed at some distance from anal point base; anal tergite with 22-32 apical setae; superior volsella digitiform, with small acute dorsomedially pointed apex; median volsella short, stout, with simple and subulate lamellae.Adult female with AR c. 0.25; vaginal floor absent, lateral margin of vagina without ventral extension; spermathecal duct longer than notum and rami combined, c. 220 µm long; notum about the same length as rami; diameter of seminal capsule c. 50 µm, slightly shorter than length of notum; cercus short, c. 37 µm long.Pupa with well developed, conical cephalic tubercle; thoracic horn c. 260 µm long and thin with numerous small chaetae scattered over almost whole length of horn; thorax smooth except for small area of granulation along scutal suture and posterior to thoracic horn; anterior dorsocentrals as long as posterior dorsocentrals; microspinule patches on tergite II-IV large, starting at or anterior to seta D1; microspinule patches on tergites V and VI two broad longitudinal rows, which can be connected anteriorly; pleura III-V with shagreen; segment V with 4 lateral taeniate setae; anal lobe with fringe of 15-16 taeniate setae.Larva with well developed (c.25-30 µm long) digitiform spur on antennal pedestal; antennal segment 1 65-70 µm long; AR c. 0.9; antennal blade c. 130 µm long; distal Lauterborn organ on 7 µm long pedicel, basal Lauterborn organ on 5 µm pedicel, placed at 1/3 length of antennal segment 2; S3 simple.
Adult female (n = 2, unless otherwise stated).Length 1.4-1.5 mm; wing 0.91-1.23 mm.Colour similar to male, but clearly paler (could be due to storage in alcohol).
Larva (n = 5, unless otherwise stated).Length c. 2.0 mm, case c. 2.5 mm long.Head capsule pale brown, somewhat darker postoccipital rim and teeth on mandible and mentum.Live specimens not examined.
Zavrelia aristata has been found in or near springs, spring brooks, small streams, bogs and seepages from Florida in the south to New Brunswick in the north of North America.The larvae build straight cases, slightly tapered towards posterior, of coarse sand grains and a few bits of detritus.

Diagnostic characters
Zavrelia casasi can be separated from other Zavrelia species by the following combination of characters.Adult male length c. 1.5 mm; AR about 0.6; frontal tubercle small, conical; anal point with c. 30 small spinules between well developed crests; c. 4 strong median tergite setae placed at some distance from anal point base; median volsella short, stout, with simple and subulate lamellae.Pupa with granulose anterior cephalothorax; moderately developed cephalic tubercles; thoracic horn comparatively short and thick with numerous small chaetae scattered along whole length; anteriormost dorsocentral long and taeniate, remaining dorsocentrals considerably shorter and simple; microspinule patches on tergite II-V large, covering most of tergite; microspinule patches on tergite VI two broad longitudinal rows; pleura II-VI with shagreen; anal lobe with c. 20 taeniate setae in a fringe.
Legs (Fig. 3E): Fore tibia with 15 µm long spur; mid and hind tibiae with well separated, 10 µm long combs, one mid tibial comb with 20 µm long spur, other with 10-12 µm long spur; one hind tibial comb with 20-25, 22 µm long spur, other with 12 µm long spur.Lengths and ratios of leg segments in Table 1.Adult female and larva unknown.
Etymology.The species is named after our colleague Jesús Casas who collected the type material.
Remarks.The pupa described above is tentatively associated with the adult males that were found at the same place and date at Lanjarón, so we regard the association to be very likely.There was only material of one female available for examination and this specimen (a pharate adult) lacked abdomen and thorax.Thus, this material was inappropriate for description.
The adult of Zavrelia casasi is morphologically closest to Z. tusimatijea from the Tsushima Islands, but can easily be separated from this species by its smaller size, lower AR and single-lobed superior volsella.Immatures of Z. tusimatijea are unknown.

Diagnostic characters
Zavrelia clinovolsella can be separated from other Zavrelia species by the following combination of characters.Length of adult male c. 1.8 mm; AR about 0.59; frontal tubercle small, conical; anal point without spinules but with a few microtrichia between long crests; c. 4 strong median setae on tergite placed at some distance from anal point base; superior volsella with abruptly tapered, sickle-shaped setiger.
Legs (Fig. 5C): Fore tibia with 18 µm long spur; mid and hind tibiae with well separated, 12 and 10 µm long combs, mid tibial combs with 25 and 15 µm long spurs, hind tibial combs with 30 and 13 µm long spurs.Lengths and ratios of leg segments in Table 1.
Adult female, pupa and larva unknown.Remarks.Zavrelia clinovolsella is recorded only by a river in the Diancan Mountains, China (Guo & Wang, 2004).

Diagnostic characters
Zavrelia hudsoni can be separated from other Zavrelia species by the following combination of characters.Length of adult male c. 2.0 mm; AR about 0.75; frontal tubercle small, conical; anal point with microtrichia, but without spinules between long crests; 11-12 strong median tergite setae placed at some distance from anal point base; superior volsella digitiform with small apical point, 5 dorsolateral and 2 median setae on setiger; median volsella short, stout, with simple and subulate lamellae.Adult female with AR c. 0.22; vaginal floor absent, lateral margin of vagina without ventral extension; spermathecal duct far longer than notum and rami combined, c. 200 µm long; notum considerable longer than rami; diameter of seminal capsule moderately long, shorter than length of notum; cercus comparatively large, 50 µm long.Pupa with well developed conical cephalic tubercle; thoracic horn long with numerous small chaetae scattered along almost whole length; thorax smooth except for small area of granulation along scutal suture and posterior to thoracic horn; anterior dorsocentrals as long as posterior dorsocentrals; microspinule patches on tergites II-IV large, semi-square, starting anterior to seta D1; microspinule patches on tergites V and VI in two large, -shaped; pleura IV-VI with shagreen; segment V with 3 taeniate lateral setae; anal lobe with 16-19 taeniate setae in fringe.Larva with well developed, (c. 25 µm long), digitiform spur on antennal pedestal; AR 0.89; antennal segment 1 c.55 µm long; distal Lauterborn organ on 7 µm long pedicel, basal Lauterborn organ on 5 µm pedicel 1/4 along length of antennal segment 2; S3 simple.
Wing: as male, except with more setae; 3.1 times longer than broad; VR not measurable.
Legs: Fore tibia with 10 µm long spur; mid and hind tibiae with well separated, 10 µm and 12 µm long combs, each with 15 and 20 µm long spurs.
Larva (n = 1).Length not measurable, case not examined.Head capsule pale brown, somewhat darker postoccipital rim and teeth on mandible and mentum.Live specimens not examined.
Etymology.The species is named after our colleague Patrick L. Hudson who collected the type material and has lent us material of many tanytarsine species for comparison and description.
Remarks.There is an additional unmacerated female with associated pupal skin from the type locality at the UMSP, which is very similar to Zavrelia hudsoni.However, this specimen is not included in the above description due to small differences in the pupal and female morphology: presence of shagreen on the pupal abdominal pleura II and III, presence of 4 taeniate lateral setae on pupal abdominal segment V and shorter (37 µm) cerci in the adult female.We regard these differences as exceeding what can be expected to be intraspecific variation in Zavrelia, but do not wish to formally describe this specimen as a separate species due to the limited number of specimens and lack of males for comparison with other Zavrelia species.Moreover, based on the pupal characters alone, the additional specimen from Tennessee is very similar to Zavrelia elenae.It is tempting to identify the P& from Tennessee as Z. elenae on this basis, but given the huge geographical distance between these two localities and the lack of crucial information on other life stages, we choose to leave the Tennessee specimen unnamed at this point.

Diagnostic characters
Zavrelia pentatoma can be separated from other Zavrelia species by the following combination of characters.Adult male with wing length c. 1.3 mm, 3.7 times longer than broad; AR about 1.2; frontal tubercle minute; anal point with numerous (>40) spinules between long anal crests; several (6-11) strong median tergite setae placed at some distance from anal point base; median volsella short, stout, with simple and subulate lamellae.Adult female with AR c. 0.28; vaginal floor absent, but lateral margin of vagina with slight ventral extension; spermathecal duct far longer than notum and rami combined, c. 300 µm long; notum considerably longer than rami; diameter of seminal capsule large (c.63 µm long), much shorter than length of notum, but longer than cercus (c.47 µm).Pupa with weakly developed cephalic tubercle; thoracic horn long and thin with numerous small chaetae scattered around middle; thorax smooth except for small area of granulation along scutal suture; anterior dorsocentrals longer than posterior dorsocentrals; microspinule patches on tergite II-V large, covering most of tergite; microspinule patches on tergite VI two broad longitudinal rows; pleura II-VI with shagreen; anal lobe with a fringe of 14-19 taeniate setae.Larva with well developed, (c.30 µm long), pointed spur on antennal pedestal; AR 1.2; antennal segment 1 c.75-90 µm long; distal Lauterborn organ on 2 µm long pedicel, basal Lauterborn organ without pedicel placed close to base of antennal segment 2; S3 simple.
Colour: Body and head dark brown, some specimens with lighter brown ground colour with dark pedicel, eye, scutal stripes, postnotum and preepisternum, scutellum paler, haltere brown.
Wing: as male, except 3.0 times longer than broad.VR 1.28.
Larva (n = 5, unless otherwise stated).Length c. 2.3 mm, case c. 3 mm long.Head capsule brown, somewhat darker postoccipital rim and teeth on mandible and mentum.Live specimens not examined.
Additional material examined: Austria (ZSM): 7 %, 4 pex, Turkey (ZSM): 1% Prov.Hakkari, S Yüksekova, 1700 m a.s.l., 28.vi.1985, W. Schacht.Remarks.The male and female types of Zavrelia pentatoma could not be located.The pupal type material is from a different locality than the larval sample from which adults were reared (Bause, 1913), but are nevertheless part of the type material since both Bause and Kieffer (in Bause, 1913) are credited the authorship of this species (Spies, 2005).The larvae from Bohemia/Moravia in the Thienemann collection (ZSM), collected by Zav el, are not regarded as part of the type material since the larval description in Bause (1913) explicitly is based on the Lauterborn material.The pharate male examined (leg.Zav el) is designated lectotype for future stability of the species taxonomy.
The type material of Zavrelia atrofasciata was not located, and is probably lost (W.Gi ka, pers. comm.).The original description (Kieffer, 1921) is quite detailed however, and is conspecific with the morphology of Z. pentatoma except for a slightly different shape and fewer setae on the superior volsella (club-shaped and 3-4 setae respectively).The larger, more developed cross vein RM reported for Z. atrofasciata by Kieffer (1921) and Goetghebuer (1937Goetghebuer ( -1954) ) is an intraspecifically variable character in Z. pentatoma, and is different even in specimens from the same locality and date.Thus, we regard Kieffer's (1921) observations to be minor misinterpretations and list Z. atrofasciata, as suspected by Gi ka (2002), as a junior synonym of Z. pentatoma.Goetghebuer (1921) considered Zavrelia nigritula to be a darker variation of Z. pentatoma, and even suggested that the differences in colouration could be associated with the preservation of the Lauterborn specimens Kieffer used.The male syntypes present in IRSNB were examined and are judged to be conspecific with Z. pentatoma.Intraspecific variation in body pigmentation is found in other chironomid species (e.g.Kobayashi & Hayashi, 2001;Mat na, 1995) and is clearly also the case for Z. pentatoma.Goetghebuer (1937Goetghebuer ( -1954) ) reports Z. nigritula to have palpomeres of increasing length, but this is not the case for the type material examined where all specimens have palpomere three longer than palpomere four.Thus, we agree with Brundin (1947) and confirm the synonymy with Z. pentatoma.Goetghebuer (1931) included both male and female symbols in the original description of S. paludosa, but perhaps apart from the colouration and the wing, the description is based only on the male (e.g., no female antenna described).The male type in IRSNB is here designated lectotype to stabilize the taxonomy.Examination of this specimen revealed that Stempellina paludosa is conspecific with Z. pentatoma.
Zavrelia pentatoma is found in or near peat pits, moor ponds and moor lakes rich in humic acids and with relatively low pH (Brundin, 1949) (c. pH 5.5 in Rollischsee, own observation).The larvae build transportable cases of detritus, sand and diatoms (Lauterborn, 1905, Figs 8, 9), and seem to be adapted to a life in temporary, oxygenpoor, shallow waters (Brundin, 1949).Although adult specimens have been collected in Bavaria in November, the emergence period is mainly midsummer (op.cit.; this study).The species is widespread in Europe and is also recorded from the eastern Palaearctic region (Saether & Spies, 2004;this study).

Diagnostic characters
Zavrelia sinica can be separated from other Zavrelia species by the following combination of characters.Length of adult male c. 2 mm; AR about 1.1; frontal tubercle large, tubular; anal point without spinules between long, high crests; c. 6 strong median tergite setae placed at some distance from anal point base; anal point crests not reaching apex of anal point; superior volsella with obvious constriction in apical 1/3 of setiger.Adult female with AR c. 0.29; vaginal floor absent, but lateral margin of vagina with slight ventral extension; spermathecal duct far longer than notum and rami combined, c. 360 µm long; notum considerable longer than rami; diameter of seminal capsule c. 66 µm, much shorter than length of notum; cercus short, 36 µm long.Pupa with well developed cephalic tubercle; thoracic horn long and thin, with numerous small chaetae scattered on distal 2/3; thorax with small areas of granulation dorsoanteriorly in particular along scutal suture and posterior to thoracic horn; anterior dorsocentrals slightly longer than posterior dorsocentrals; microspinule patches on tergite II-V large, covering most of tergite; microspinule patches on tergite VI two broad semi-triangular patches; pleura II-VI with shagreen; segment V with 3 lateral taeniate setae; anal lobe with 18 taeniate setae in fringe.Larva with well developed (c.21 µm long), digitiform spur on long (c.84 µm) antennal pedestal; antennal segment 1 c.66 µm long; AR 0.90; distal Lauterborn organ on 14 µm long pedicel, basal Lauterborn organ on 6 µm pedicel positioned 1/3 along length of antennal segment 2; antennal blade c. 100 µm long; S3 simple.
Adult female (n = 1).Length 2.4 mm; wing unfolded.Colour as male, but somewhat paler (could be due to storage in alcohol).
Posterolateral spur on segment VIII occasionally bifurcate.
Etymology."sinica", Latin adjective meaning Chinese, referring to the country in which the holotype was found.
Remarks.The adult male of Zavrelia sinica is perhaps most similar to Z. elenae Zorina, 2008 andZ. pseudopentatoma Zorina, 2008, but can be separated from both these species by having anal point crests that do not reach the anal point apex and by the presence of distinct microtrichia-free areas around the base of the anal point.The pupa of Z. sinica closely resembles that of Z. pseudopentatoma, but can be separated by having semitaeniate lateral setae on the abdominal segment III and shagreen on pleura II-VI.The larva is almost identical to that of Z. elenae and can only be separated by antennal morphometrics and the number of spines on mola.
Zavrelia sinica was found in a stream along the road between Antu and Songjiang in the Jilin Province (c. 10 km S of Songjiang), and in the North Korean Kymgang-san mountains.The larvae build transportable cases of comparatively coarse sand grains.

Diagnostic characters
Zavrelia tusimatijea can be separated from other Zavrelia species by the following combination of charac-ters: Frontal tubercle small white spot, AR c. 1.2; anal point with numerous small spinules between well developed crests; apex of superior volsella divided into a ventral point and a dorsal lobe, two setae placed on ventrolateral sculpturing of setiger.
Colour: Body more or less uniformly dark brown with light brown legs and scutellum.Eyes somewhat darker ventrally.
Legs (Fig. 12D): Front tibia with small scale, 20 µm long spur; middle tibial combs 15 µm long with 30 µm and 20 µm long spurs; hind tibial combs 15 µm long with 30 µm and 25 µm long spurs.Lengths and ratios of leg segments in Table 1.20 small spinules scattered between long, low anal crests, apex rounded; no microtrichia free area around base of anal point.Superior volsella triangular with 3 dorsal, 2 ventral and 2 median setae on setiger; setiger with apex horizontally divided in ventral point and dorsal lobe, rounded knob with 2 setae ventrolaterally; microtrichia apparently absent from superior volsella.Median volsella short knob, with medially directed subulate lamellae.Inferior volsella slightly club-shaped with about 12 dorsoapical setae.Inner margin of gonocoxite with 4 strong setae.
Remarks.This species was originally described as a member of Tanytarsus, but both the original description and examination of the holotype reveal that it belongs to Zavrelia.This was recognized by Ekrem (2002).Zavrelia tusimatijea has so far only been recorded from its type locality on Tsushima Island in the Korea Strait and this record constitutes the southernmost distribution of Zavrelia in the Palaearctic region.

Key to Zavrelia larvae
The larvae of the following species are unknown: Zavrelia bragremia, Z. casasi, Z. clinovolsella and Z. tusimatijea.

DISCUSSION
Several Zavrelia species are morphologically similar and can be difficult to separate if only one life stage is available.Also, it must be added that some of the species descriptions above are based on few specimens and that larger ranges of intraspecific variation probably will be detected if more material becomes available.Partial COI sequences (so called DNA barcodes) have proven useful for species identification and delimitation of related genera (Ekrem, 2007).Unfortunately, in this study only material of Z. pentatoma was found suitable for molecular analyses.Thus, whether DNA barcodes can be used to separate species of the genus Zavrelia must remain unanswered until fresh material of more species is sampled.
This and other recent studies (Zorina, 2008;Guo & Wang, 2007) suggest some minor emendations to the previously established diagnoses of males, larvae and pupae of the genus (Cranston et al., 1989;Pinder & Reiss, 1983, 1986).A diagnosis of Zavrelia adult females was first attempted by Saether (1977, p. 142), and although most of his findings are confirmed by this study, none of our specimens had a large floor under the anterior part of the vagina.In fact, the lack of such a floor seems to be a good character to separate Zavrelia females from those of closely related genera, for instance Stempellinella (see Fig. 13).Among the genera within the tribe Tanytarsini, both Zavrelia and Afrozavrelia lack a vaginal floor, but these two genera can be separated by a number of other features (Harrison, 2004).The question thus remains if the female(s) with a vaginal floor identified as Zavrelia sp. by Saether (1977) should be regarded as congeneric to the species described above.Until evidence is presented that associated Zavrelia females possess a vaginal floor, we are of the opinion that it should not.Indeed, females of a new hairy eyed Tanytarsini species from California, recently made available to us by Peter Cranston, possess a floor under the anterior part of vagina.However, although generally similar to Zavrelia in many aspects, this species has several other diagnostic characters that differ from what we so far have observed in Zavrelia species (e.g., macrotrichia are present on subcosta, the male anal tergite band is simple and transverse, and only one tibial comb bears a spur).Our supposition is that there are new species in the Holarctic Region that are probably best placed in one or more separate new genera rather than enlarging existing generic diagnoses.This hypothesis needs to be confirmed by phylogenetic analyses.As a result of our observations and the proposed change in the diagnostics for Zavrelia, one of the two unique synapomorphies for the tribe Tanytarsini reported by Saether & Roque (2004) is invalid and might alter an already unstable phylogeny of the tribe Tanytarsini.The actual effect of this and other inadequate character codings by Saether & Roque (2004) is currently under investigation (Ekrem, in prep.).