Hydrobaenus korneyevi (Baranov, 2011) Moubayed-Breil & Baranov, 2018

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 : 349-351

Hydrobaenus korneyevi (Baranov, 2011) , comb. nov.

( Figs 10–20 , 25–26, 29 )

Parorthocladius korneyevi Baranov, 2011a: 406 .

Type material examined. HOLOTYPE: ♁ ( SIZK), ʻ UKRAINE: CRIMEA: leg. V. Baranov; Simferopol, Salgir River , 29.XI.2010, handnetʼ. PARATYPES: 2 ♁♁ ( JBMF), same locality as for holotype.

Diagnosis. The description of male adult of H. korneyevi , as provided in the original paper ( BARANOV 2011a), can be completed and supplemented with the following additional characters: lobes of antepronotum distinctly gaping; acrostichals reduced, composed of 4–5 setae starting some distance from antepronotum; sensilla chaetica present on tibia and tarsomeres ta 1 –ta 5 of PI, PII and PIII; tergite IX broadly triangular and narrowing distally, bearing medially a distinct elevated truncate hump; distal part of tergite IX and anal point densely covered with about 60 setae which are placed mainly on sides of dorsal hump; anal point triangular to drop-shaped, elongate, nearly parallel-sided to weakly narrowing distally, ending with a short finger-like apex; virga consisting of 6–8 long subequal thin spines; inferior volsella composed of 2 distinct lobes, proximal one semi-spherical and much larger; gonostylus massively bulbous medially, with blackish long and short setae covering posterior and lateral sides; crista dorsalis consisting of strong preapical triangular tooth, orally projecting and placed close to megaseta, which is markedly bent inwards. Redescription. Male adult (n = 3; Figs 10–20 , 25–26, 29 ). Large sized Hydrobaenus species. Total length 4.40–4.60 mm; wing length 2.60–2.70 mm. General colouration blackish with contrasting brown to blackish thorax and legs. Mesonotal stripes distinctly blackish; legs dark brown to blackish; tergites I–VIII brown to dark brown; anal segment blackish, crista dorsalis distinctly dark brown.

Head. Eyes bare. Temporals consisting of 12–13 setae including 7–8 inner and 5 outer verticals. Antenna 810– 830 μm long, 13-segmented, length (μm) of segments: 1, 50; 2–12, 30–35 (nearly sub-equal), last flagellomere 420–430; distal part of last flagellomere ( Figs 23–24 ) moderately clubbed ending with forked rounded apex; antennal groove beginning on segment 1 and reaching ultimate flagellomere; AR 1.10. Clypeus with 8 setae. Palp 5-segmented, not reduced, palpomere 3 ( Fig. 10 ) with 4–5 sensilla clavata.

Thorax. Lobes of antepronotum ( Fig. 29 ) distinctly gaping, lateral antepronotals 6–7; acrostichals ( Fig. 11 ) reduced, composed of 4–5 setae in 1 row, starting some distance from antepronotum; dorsocentrals 15–17 in 2 rows; prealars 4–5 in 1 row. Scutellum with 13–14 setae in 2 rows. Wing. Brachiolum with 1 seta. Distribution of setae on veins: R, 8–9; R 1, 0; R 2+3, 1–2; remaining veins bare. Squama with 10–14 setae in 1–2 rows. Legs. Sensilla chaetica present on tibia and tarsomeres ta 1 –ta 5 of PI, PII and PIII. Length (μm) and proportions of legs as in Table l. Hypopygium in dorsal and ventral view ( Figs 15–16 ). Tergite IX broadly triangular, narrowing distally, with elevated truncate hump medially ( Figs 12–14 ) which is clearly visible in lateral view, distal part of tergite IX and anal point densely covered with setae (about 60). Anal point ( Figs 12–14 ) about 90–100 μm long, 60–70 μm maximum width at base and 20–25 μm at apex, long triangle to parallel-sided, slightly narrowing distally, entirely covered with setae (less at base than at apex), apex ending with small finger-like apex ( Figs 12 a–12b). Virga ( Figs 15–16, 18 ) consisting of 6–8 subequal fine spines about 55–60 μm long and fused at base. Gonocoxite 250–260 μm long, maximum width 125–130 μm, with rounded apex; inferior volsella (dorsal, Figs 15, 17 ) composed of 2 large lobes, proximal lobe distinctly larger and semi-circular. Gonostylus ( Figs 19–20 ) 120–125 μm long, maximum width 60–70 μm, massively bulb-shaped; posterior and posterolateral margins densely covered with characteristic short and stout blackish setae, posterior and lateral side with 9–10 long stout characteristic setae; crista dorsalis consistently chitinous, triangular with pointed apex, orally directed and placed pre-apically close to megaseta, clearly visible in both dorsal and lateral view ( Figs 19–20 ); megaseta about 20 μm long, markedly bent inwards.

Taxonomic position. The male adult of H. korneyevi resembles that of H. dentistylus and H. lugubris in having a similar shape of inferior volsella and a high number of setae on tergite IX and anal point. Nevertheless, the massive structure of gonostylus and the strong triangular crista dorsalis look more similar to those of H. dentistylus . However, H. korneyevi can be separated from other related Hydrobaenus species by the following characters: presence of a distinct truncate elevated hump on median part of tergite IX (clearly visible in lateral view); anal point long triangle to long drop-shaped, often ending in a finger-like apex ( Figs 12 a–12b); virga with 6–8 long thin spines; lobes of inferior volsella differently shaped, proximal one rounded and much larger; gonostylus densely covered with blackish short and long setae, crista dorsalis strong tooth-like, triangular with pointed apex, placed pre-apically close to megaseta.

Ecology. Male adults of H. korneyevi are collected only during winter time between December and January: dates of emergence recorded in the Salgir River basin are: 29.12.2010 and 21.1.2013. Adults were recorded swarming, flying and moving on the vegetation and on the snow at low temperatures (<-2°C). Species is recorded from piedmont rivers, with gravel substrates and plenty of accumulated organic matter, such as leaves and bark.

Distribution. Hydrobaenus korneyevi is reported from the Central part of the Crimean Peninsula, including its type locality (the Salgir river in Gagarin Park in the centre of Simferopol) as well as from Botanical Garden of Taurida State University and from Western Bulganak river, next to Pozharske village ( BARANOV 2011a,b).

Figures

Figs 10–20. Male adult of Hydrobaenus korneyevi (Baranov, 2011). 10 – palpomere 3; 11 – distribution pattern of acrostichals; 12–13 – tergite IX and anal point (12–13 – dorsal view; 14 – lateral view); 15–16 – hypoygium, gonostylus removed (15 – dorsal view; 16 – ventral view, tergite IX and anal point removed); 17 – inferior volsella, dorsal view; 18 – virga; 19–20 – gonostylus (19 – dorsal view; 20 – lateral view).

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.