Hydrellia aurifer Cresson, 1932

Zatwarnicki, Tadeusz & Kejval, Zbyněk, 2024, Two new species of Hydrellia (Diptera: Ephydridae) from Central Europe, with redescriptions of H. aurifer and H. frontalis, Acta Entomologica Musei Nationalis Pragae 64 (2), pp. 345-353 : 349-352

Hydrellia aurifer Cresson, 1932

( Figs 15–24 )

Hydrellia aurifer Cresson, 1932: 21 .

Type locality. Western Ukraine (see Remarks).

Type material examined. HOLOTYPF: J, double mounted in poor condition ( Fig. 20 ), labelled:ʽHalicia 8. 79 (Wachtl) Mik [date handwritten,the rest printed] // J TYPE No. 6614 Hydrellia AURIFERA E. T. Cresson, Jr. [red label, number and name handwritten, the rest printed]ʼ ( ANSP). Additional specimens examined. CZECH REPUBLIC: BOHEMIA: Dolní Lhota, 49°22′31″N 13°14′41.5″E, alt. 400 m, Luňáky Nature Reserve, overgrown bottom of pond, yellow pan trap, 20.V.2022, Z. Kejval leg., 1 J ( MCH). UNITED KINGDOM: CAMBRIDGESHIRE: Ouse Washes, Mepal, 52°25′42.2″N 00°08′55.7″E, swept, 23.vii.2004, M. Drake leg., 1 J ( MDAUK).

Redescription. Male. Small shore flies; body length 2.7 mm, wing length 2.8 mm.

Head. Frons strongly transverse; parafrons brownishgrey, frontal vitta slightly paler, dark grey ( Fig. 16 ); ocellar, pseudopostocellar and fronto-orbital setae nearly equal, rather long, about 0.8 times as long as inner vertical seta. Antenna with scape and pedicel brownish black, basal flagellomere brownish black ( Figs 15, 16 ); arista with 5–7 dorsal rays. Lunula brownish grey; face in anterior view brown with cupreous tinge, in lateral view slightly evenly arcuate; 6 facial setulae, minute to rather long; palpus dark brown, moderately broadened distally ( Fig. 16 ); eye to gena ratio 5.80.

Thorax. Mesonotum subshiny, largely brownish or brownish grey, moderately paler, grey with slight bluish tinge anteriorly and laterally on notopleuron, scutellum brownish grey; pleura paler, grey with slight bluish tinge ( Fig. 15 ). Presutural dorsocentral setae nearly as long as first postsutural seta. Legs comparatively long, entirely dark grey to brownish grey ( Fig. 15 ), fore coxa and tibia with slight bluish tinge; covered by grey microtomentum, except for posterior side of hind legs; fore femur bears postero-ventral row of setulae; distal half of mid femur bears anterior row of setulae. Wing slightly infuscate; veins largely brownish black, paler at wing base; costal vein ratio 0.64; M vein ratio 0.67; knob of halter white, stem pale reddish.

Abdomen. All terga dull and largely dark grey, moderately paler with slight bluish tinge on lateral sides; male fifth to fourth tergite ratio about 1.0. Epandrium in dorsal view broadly U-shaped with narrow lateral arms ( Figs 17, 21 ), producing large cercal cavity, arms in lateral view narrow, sickle-shaped ( Fig. 22 ), each bearing at least 3 strong setae ( Figs 17 ); cercus conspicuously large, in dorsal view subtriangular ( Figs 17, 21 ); genital plate in dorsal view moderately transverse, 0.6 times as long as wide, trapezoidal, with apical margin subtruncate, shallowly emarginate medially, and shortly densely setose ( Figs 17, 21 ), in lateral view lanceolate ( Fig. 22 ); aedeagus elongate, in dorsal view 2.32 times as long as wide, arrowhead-shaped with medio-lateral flaps, rounded posterior margin, and strongly narrowed anterior portion ( Fig. 18 ), in lateral 3.65 times as long as wide, irregularly ovoid, with anterior corniform process ( Figs 18, 24 ); phallapodeme in dorsal view spatulate to shortly bifurcate anteriorly ( Figs 19, 23 ), in lateral view reversed J-shaped with small ventro-medial projection ( Fig. 24 ); postgonite in dorsal view J-shaped with major section rhomboidal, anterior process of postgonite Z-shaped with broader base ( Figs 19, 23 ); postgonite in lateral view narrow, with anterior process Z-shaped ( Fig. 24 ); pregonite short, straight, with apex narrowed and bearing two setulae ( Figs 23, 24 ); hypandrium in dorsal view bullet-shaped with rounded anterior margin ( Figs 23 ), in lateral view semi-circular, moderately depressed ( Fig. 24 ); 5 th sternum consisting of two oval sclerites, narrowly separated medially, with numerous setulae arranged along postero-median margins and on adjacent ventral surface ( Figs 19, 23, 24 ).

Female. Unknown.

Biology. The two new records come from the following habitats: strongly overgrown bottom of shallow pond (CZ) and ditch margin in swamp-like pasture in an annually flooded river floodplain, dominated by Glyceria maxima and Sparganium erectum , with Mentha aqutica , Eleocharis palustris and some Butomus umbellatus ( UK, M. Drake, pers. comm.). The specimens were collected by sweeping vegetation and by using water pan traps (yellow and white, diameter ca. 20 cm).

Distribution. Czech Republic (new record), Ukraine (CRFssON 1932), United Kingdom (new record).

Remarks. CRFssON (1932) described Hydrellia aurifer from a single male specimen originating from ʽHaliciaʼ (= Galicja, Galizien), which was an eastern province of the former Austro-Hungarian Empire. Its collector, Fryderyk (also as Fritz) Wachtl, was from 1876 a superintendent forester at Taniawa, a village located 20 km S of Stryj (present Ukraine). He later had a position close to Wien (Vienna) and may have visited Taniawa during summers (HFLLRIGL 2015). The holotype specimen bears a bit different species name ʽ Hydrellia aurifera ʼ which is probably just an initial version. The species epithet ending in - fer should be treated as noun in apposition (see ICZN 1999: 31.2.2).

Figures

Figs 15–24. Hydrellia aurifer Cresson, 1932. 15–19 – male (Czech Republic, Dolní Lhota): 15 – head and thorax, lateral view; 16 – head, anterior view; 17 – epandrium, cerci, and genital plate, dorsal view; 18 – aedeagus in dorsal (left) and lateral (right) view; 19 – 5th sternum, gonites and phallapodeme, dorsal view. 20–24 – male (holotype, Ukraine): 20 – body in antero-oblique view; 21 – epandrium, cerci, and genital plate, dorsal view; 22 – ditto, lateral view; 23 – 5th sternum and internal terminalia, dorsal view; 24 – ditto, lateral view. Scale bar = 0.1 mm (Figs 17–19, 21–24).