Eur. J. Entomol. 106: 119–144, 2009 http://www.eje.cz/scripts/viewabstract.php?abstract=1433 ISSN 1210-5759 (print), 1802-8829 (online) A review of the genus Zavrelia (Diptera: Chironomidae) TORBJØRN EKREM and ELISABETH STUR Norwegian University of Science and Technology, Museum of Natural History and Archaeology, NO-7491 Trondheim, Norway; e-mails: [email protected]; [email protected] Key words. Chironomidae, Zavrelia, generic diagnosis, keys, taxonomy, immature stages Abstract. 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 1954, listed as doubtful species in the Palaearctic cata- Species of the genus Zavrelia Kieffer, Thienemann & logue, is regarded as a junior synonym of Stempellinella Bause in Bause (1913) are small to minute chironomids ciliaris Goetghebuer, 1944 by Ekrem (2007). At least one (non-biting midges), which are recorded from both conti- Zavrelia species was recognised previously in the Nearc- nents of the northern hemisphere. Zavrelia species seem tic, but none have been described formally and named to be less common than species of their presumed sister from this region yet (Epler, 2001; Oliver et al., 1990). genus Stempellinella, but when encountered, the larvae Regarding the Afrotropical region, Kieffer (1923) and pupae of Zavrelia are normally found in unpolluted described Zavrelia kribiensis from southern Africa and streams and rivers. One exception is the western Cameroon and the species was maintained by Freeman Palaearctic species Zavrelia pentatoma which is so far (1958). However, Z. kribiensis is morphologically quite only recorded from standing waters rich in humic acids different from other Zavrelia species in all life stages and on or near moors. All known larvae of Zavrelia species was placed in a new genus Afrozavrelia by Harrison construct small, straight transportable cases of sand, silt, (2004). The Catalogue of the Diptera of the Oriental detritus and sometimes diatoms that function as retreats Region (Sublette & Sublette, 1973) lists one unnamed until the mature pupa swims to the surface prior to adult species from Java reported by ZavĜel (1934), but not emergence. described so it is not possible to say if it is a Zavrelia or a The argument for the erection of the genus Zavrelia member of the more widely distributed genus Stempelli- was presented in part as personal communication from nella. Kieffer (Bause, 1913, p. 100), but since the genus is More recently, Tanytarsus tusimatijeus Sasa & Suzuki, defined by both larval and pupal characters in the identifi- 1999 was described from Tsushima Island (Sasa & cation key provided in the same work (op. cit. p. 42–45 & Suzuki, 1999) and transferred to Zavrelia by Ekrem p. 89–93), the authorship of the genus must also be cred- (2006). In addition, two new species of Zavrelia were ited to Bause. In addition, a footnote in the final chapter described from China (Guo & Wang, 2004, 2007) and (p. 118) states that Thienemann must be regarded as another two from Russia (Zorina, 2008). Including the author of the presented classification in which the diag- four species new to science described below, the genus nostic characters are commented on. Thus, we agree with Zavrelia now contains a total of ten species. Spies (2005) that Kieffer, Thienemann and Bause all must Systematically, the genus Zavrelia is placed within the be credited with the authorship of Zavrelia. subtribe Zavreliina of the tribe Tanytarsini in the sub- Until recently, there were few Zavrelia species known family Chironominae (Ekrem & Sæther, 2000; Sæther & to science. The Catalogue of Palaearctic Diptera (Ashe & Roque, 2004). Morphologically, the genus is similar to its Cranston, 1990) and the later Manual of Palaearctic Di- presumed sister genus Stempellinella, particularly in the ptera (Sæther et al., 2000) both list three valid species immature stages. Some characters in particular seem to be from the Palaearctic region. One of these, Zavrelia kibun- useful for separating the two genera (see Ekrem, 2007, ensis Tokunaga, 1938, was transferred to the genus Neo- Table II, p. 1374), although examination of more associ- zavrelia (Ekrem, 2006), and Zavrelia atrofasciata is ated Zavrelia pupae has revealed that not all species have below regarded as a junior synonym of Z. pentatoma. In shagreen on pleura II and that it is not necessarily addition, Zavrelia inopinata Botnariuc & Cindea-Cure, arranged in distinct rows (this character was erroneously 119 listed under Stempellinella by Ekrem, 2007). Preliminary Imago phylogenetic analyses based on two nuclear and three Small species, wing length about 0.8–1.5 mm. Body mitochondrial markers indicate that the two genera are with ground colour green or light brown or brown to indeed separate monophyletic groups and thus should be black; vittae distinct if ground colour light. maintained as entities at the same taxonomic level Antenna. 10 easily discernible flagellomeres in male (Ekrem, in prep.). (distribution of antennal setae indicate 13 flagellomeres); The main aim of this study was to revise and describe 5 flagellomeres in female. Male antennal ratio 0.5–1.4. known and previously unknown species in the genus Head. Eye hairy, without dorsomedian extension; Zavrelia and present identification keys to all major life frontal tubercles small to well developed; palp normally stages as well as an emended diagnosis of the genus. developed. MATERIAL AND METHODS Thorax. Antepronotal lobes widely separated; scutum overreaching antepronotum; scutal tubercle absent; ante- We did some field work in Germany to supplement material pronotals absent; acrostichals present; up to 9 uniserial on loan from collections and colleagues in Europe, North dorsocentrals; humerals absent or present; 1 prealar; America and Asia. The morphological terminology and abbreviations follow supraalars absent; 2–7 scutellars. Sæther (1980). The term “taeniate” (Langton, 1994) is used for Wing. Membrane with setae in all cells except anterior the flattened setae on the pupal exuviae, and the term “setiger”, to vein M; all veins with setae except M and Sc. Costa not introduced by Spies (1998), is used for the setae-bearing part of produced; R4+5 ending proximal to apex of M3+4; anal lobe the superior volsella of the male hypopygium. The following not developed; squama bare. Female with slightly more additional abbreviations are used: AAR – larval antennal setae on wing compared to male, but M, Sc and cells pedestal/antennal segment 1 length ratio; AHR – larval antennal anterior to M bare. pedestal/head length ratio; L – larva; Lex – larval exuviae; LP – Legs. Apex of fore tibia with short, slender spur. & associated larva and pupa; LP – associated larva, pupa and Combs of mid and hind tibiae small, both bearing spurs, adult female; LP% – associated larva, pupa and adult male; LOR – lauterborn organ/antennal segments 3–5 length ratio; often one long and one short. Sensilla chaetica apparently MVR – mentum/ventromental plate width ratio; P – pupa; Pex – absent from all tarsomeres. Pulvilli absent. pupal exuviae; P& – associated pupa and adult female; P% – Male hypopygium. Anal tergite bands at least partially associated pupa and adult male. encircling several long median tergite setae placed at dis- Measurements are given as ranges, followed by the mean with tance from anal point base, or median setae absent; the number of observed specimens in parenthesis if different laterosternite IX usually with seta. Anal point well devel- from the number included in the description. Measurement oped, tapering distally, with long or short anal crests, methods follow Soponis (1977). The antennal ratio (AR) is extending onto anal tergite, with or without spinules measured on 10 flagellomeres. The lengths of the male genital and/or microtrichia in between. Setiger of superior volsellae were measured along their median margin, and of the volsella short, flattened, with digitiform or acute, medi- anal point from the anterior ends of the anal crests to the anal point apex. In the larvae, the antennal pedestal length was meas- ally directed tip; with 2 robust setae on distal inner mar- ured along the median pedestal margin, excluding spur; antennal gin; digitus absent. Median volsella very short, with distal segments were measured from their base to the non-sclerotized clump of several long, slightly curved, setiform and apex, Lauterborn organs and pedicels were measured separately. lamelliform lamellae. Inferior volsella well developed, All described larvae are fourth instar. extending beyond base of gonostylus, sometimes nearly Collections (with abbreviations