Rugilus, Leach, 1819

Sapieja, Mateusz, Ranocha, Magdalena & Melke, Andrzej, 2022, Distribution of Rugilus mixtus (Lohse, 1956) (Coleoptera: Staphylinidae: Paederinae) in Poland with comments of its morphology and ecological preferences, Zootaxa 5100 (2), pp. 249-258 : 255-256

The identification key for central European representatives of the genus Rugilus with yellow-tipped elytra:

1. Body length not smaller than 5.0 mm................................................................ R. similis

– Body length smaller than 5.0 mm..........................................................................2

2. Head oval, wider than elytra (HI—1:1.13~1.21, HEI—1: 1.06–1.10). Eye twice as long as temple (ETI—1.96–2.14). Elytra black, sometimes with a dark maroon tinge. Legs yellow. Male abdominal sternite VIII with two pairs of long symmetrically set bristles in the middle of a segment and posterior margin ( Fig. 9 ). Aedeagus as in Fig. 17, 20............... R . erichsonii

– Head width equal to or less than elytra width, eye shorter than two temple lengths. Aedeagus different................... 3

3. Head oval, wider than long (HI ranges 1.13–1.14), as wide as or slightly narrower than elytra (HEI—1:0.97). Fourth segment of antennae clavate (4ASI—1:0.83–0.93) ( Fig. 13 ). Eye almost twice as long as temple (ETI—1.83–1.87). Elytra dark maroon. Legs maroon. Length index of the first posterior tarsal segment to its total length 1:0.28–0.29 ( Fig. 11 ). Male abdominal sternite VIII triangularly cut ( Lohse 1956). Aedeagus as in Figs. 15, 18............................................ R . mixtus

– Head slightly wider than length (HI ranges 1:1.06–1.09) and much narrower than elytra (HEI—1:0.86–0.90). Fourth antennal segment barrel-shaped (4ASI—1:0.72–0.81) ( Fig. 14 ). Eye about 1.5 times longer than temple (ETI ranges 1:1.50–1.55). Elytra black with markedly contrasting yellow spots at posterior margins. Legs yellow. Length index of the first posterior tarsal segment to the total length 1:0.31–0.33 ( Fig. 12 ). Male abdominal sternite VIII rounded cut, with one pair symmetrically set long bristles at posterior margin ( Fig. 10 ). Aedeagus as in Figs. 16, 19.................................. R . orbiculatus

Figures

FIGURES 9-14. VII sternite (9, 10), right metatarsi (11, 12) and right antennae (13, 14); Rugilus erichsoni (9), Rugilus orbiculatus (10, 12, 14), Rugilus mixtus (11, 13).

FIGURES 15-20. Aedeagus in ventral (15, 16, 17) and lateral (18, 19, 20) view; Rugilus mixtus (15, 18), Rugilus orbiculatus (16, 19), Rugilus erichsoni (17, 20).