Hydrobaenus lugubris Fries, 1830

Moubayed-Breil, Joel & Baranov, Viktor, 2018, Taxonomic notes on the genus Hydrobaenus with description of H. simferopolus sp. nov. from Crimea (Diptera: Chironomidae), Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 58 (2), pp. 347-355 : 351-352

Hydrobaenus lugubris Fries, 1830

( Figs 21, 22, 27, 30–34 )

Material examined. FRANCE: Vosges Region, Mairy and Valtin areas, 400–600 m a.s.l., 24.ii.2014 & 11.iii.2014, 47 ♁♁ 6♀♀, Gennaro Coppa lgt.( JBMF); Natural Reserve of Lake Remoray, 27.xi.2017, 2♀♀ (pupal exuviae), Bruno Tissot lgt. ( JBMF).

Diagnosis. Male adult of H. lugubris resembles that of H dentistylus and H. korneyevi in having: a similar shape of inferior volsella; high number of dorsal setae on tergite IX and anal point. Its description, as provided in SAETHER (1976), can be supplemented by the following additional relevant characters: antenna, palp and legs reduced; palpomere 3 without 3 sensilla clavata; acrostichals not reduced, composed of 4–6 curved setae in 1 row; sensilla chaetica present on tibia and tarsomeres ta 1 –ta 5 of PI–PIII, tarsomere ta 4 of PI–PII distinctly shorter than ta 5, BR of all legs lower than 1 (0.60–0.95); tergite IX with distinct elevated hump clearly visible in lateral view), anterior part with blackish transverse band, about 130–140 setae present on tergite I and anal point; anal point drop-shaped; virga present, consisting of 4–5 long unequal thin spines; inferior volsella composed of 2 subequal well separated lobes; gonostylus without crista dorsalis.

Redescription. Male adult (n = 5; Figs 21–22, 27, 31–34 , 38 ). Medium sized Hydrobaenus species. Total length 3.60–3.80 mm; wing length 1.75–1.85 mm. General colouration contrasting brownish to yellowish with contrasting brown to dark brown thorax, legs and abdomen. Head brownish; legs dark brown; abdomen with contrasting brownish to yellowish tergites and sternites, anal segment brown to dark brown.

Head. Eyes bare. Temporals consisting of 21–23 setae including 13–14 inner and 8–9 outer verticals.Antenna and palp reduced. Antenna 410–430 μm long, 13-segmented; last flagellomere ( Fig. 21 , with 2 preceding segments) 180–190 μm long, entirely divided with forked rounded apex ( Fig. 21 ); antennal groove beginning on segment 1 and reaching ultimate flagellomere;AR 0.53–0.61. Clypeus with about 40 setae placed in 6–7 rows. Palp ( Fig. 22 ) reduced, 5-segmented, palpomeres 1–4 fused, palpomere 3 without sensilla clavata.

Thorax. Acrostichals ( Fig. 38 ) not reduced, consisting of 4–6 markedly curved setae 30–35 μm long, starting some distance from antepronotum and placed in 1 row; antepronotum ( Fig. 29 ) with 17–21 lateral antepronotals; prealars 5– 5 in 1 row. Scutellum with 30–35 setae in 5–6 rows. Wing. Brachiolum with 5–6 setae. Distribution of setae on veins: R, 17–19; R 1, 4–5; R 2+3, 5–6; R 4+5, 2–3, remaining veins bare. Squama with 10–13 uniserial setae. Legs. Sensilla chaetica present on tibia and tarsomeres ta 1 –ta 5 of PI–PIII, tarsomere ta 4 of PI–PII distinctly shorter than ta 5, BR of all legs lower than 1 (0.60–0.95). Length (μm) and proportions of legs as in Table 2.

Hypopygium in dorsal view ( Fig. 31 ). Tergite IX semicircular, narrowing distally, distinctly truncate medially (clearly visible in lateral view, Fig. 30 ), about 130–140 setae present on tergite IX and anal point. Anal point drop-like; virga consisting of 4–5 long unequal thin spines; inferior volsella composed of 2 subequal well separated large lobes. Gonostylus ( Fig. 34 , lateral) elongated and narrowing distally, anterior area with 9–10 stout setae which are orally directed, crista dorsalis as low elongated ridge or absent; megaseta conspicuous and slightly bent inwards. Ecology. Up to 50 male and female adults of H. lugubris have been examined based on large material collected in cold limnocrenes and pristine peat bogs located in NE-France. Emergence of chironomid fauna reported from February to March revealed that H. lugubris largely dominates the other associated species which are mainly encountered during the first seasonal inundations of floodplains of some rivers and streams located in both the Vosges Region and upper basin of the River Doubs. Species encountered in the same localities with H. lugubris include: Bryophaenocladius aestivus (Brundin, 1947) , B. nidorum (Edwards, 1929) , Chaetocladius dentiforceps (Edwards, 1929) , C. melaleucus (Meigen, 1818) , C. perennis (Meigen, 1830) , Limnophyes pentaplastus (Kieffer, 1921) , L. difficilis Brundin, 1947 , Metriocnemus albolineatus Meigen, 1818 , M. eurynotus (Holmgren, 1883) , M. fuscipes (Holmgren, 1818) , M. hirticollis (Staeger, 1839) .

Distribution. Hydrobaenus lugubris is actually widespread in Europe and the Palaearctic Region ( FRIES 1830, ZETTERSTEDT 1850, GIARD 1904, SAETHER 1976, SERRA- TOSIO & LAVILLE 1991, BARANOV 2011b). In France, this species was reported for the first time from North Western areas ( GIARD 1904). Records cited here from NE-France, after MOUBAYED- BREIL (2017), are coming from Vosges Region and the upper basin of the Doubs River (altitude 400–600 m). This is considered to be the second record from France.

Figures

Figs 21–34. Male adult of Hydrobaenus spp. 21 – H. lugubris: last flagellomere and two preceding segments; 22 – palp, reduced. 23–26 – last flagellomere and preceding segment: 23–24 – H. dentistylus; 25–26 – H. korneyevi. 27–29 – antepronotum: 27 – H. lugubris; 28 – H. simferopolus sp. nov.; 29 – H. korneyevi. 30 – H. lugubris, tergite IX and anal point, lateral view; 31–32 – hypopygium with gonostylus removed (31 – dorsal view; 32 – lateral view); 33 – virga; 34 – gonostylus, lateral.

Figs 35–47. Male adult of Hydrobaenus spp. 35–36 – H. simferopolus sp. nov.: 35 – palpomere 3; 36 – palpomere 4. 37–38 – distribution pattern of acrostichals: 37 – H. simferopolus sp. nov.; 38 – H. lugubris. 39–40 – H. simferopolus sp. nov., hypoygium, gonostylus removed (39 – dorsal view; 40 – ventral view, tergite IX and anal point removed). 41–42 – tergite IX and anal point (41 – lateral; 42 – dorsal). 43 – inferior volsella, dorsal; 44 – virga, two aspects; 45–46 – gonostylus (45 – dorsal view; 46 – ventrolateral view). 47 – gonocoxite and inferior volsella, lateral.