Key to adult males of the Pericoma trifasciata group

Note: The adult males of P. incrustans Vaillant and P. barremica Vaillant & Withers are still undescribed. A key to fourth instar larvae is given by Vaillant & Withers (1993).

1. Gonostylus with preapical bristle (fig. 2C).................................................................. 2

- Gonostylus without preapical bristle....................................................................... 9

2. Narrow part of gonostylus shorter than broad part (Vaillant 1978, plate LXII, fig. 5)............. P. viperina Vaillant, 1961

- Narrow part of gonostylus equal to or much longer than broad part.............................................. 3

3. Phallic sheath without deep indentation medially. Surstyli with five or six tenacula.................................. 4

- Phallic sheath with deep indentation medially (e.g. Vaillant & Withers 1993, fig. 3). Surstyli with five tenacula........... 6

4. Surstyli each with five tenacula..................................................... Pericoma miljenkoi sp.nov.

- Surstyli each with six tenacula........................................................................... 5

5. Phallic sheath shorter than epandrium (Vaillant 1978, plate LXII, fig. 9). Narrow part of gonostylus equal to length of broad part.............................................................................. P. pallida Vaillant, 1978

- Phallic sheath longer than epandrium (Vaillant & Withers 1993, fig. 14). Narrow part of gonostylus much longer than broad part.................................................................... P. calcifera Vaillant & Withers, 1993

6. Lateral margins of phallic sheath parallel, medial indentation as broad as lateral lobes of phallic sheath.................. 7

- Lateral margins of phallic sheath diverging, medial indentation half as broad as lateral lobes of phallic sheath (Vaillant 19 78, plate LXII, fig. 12)................................................................. P. tonnoiri Vaillant, 1978

7. Base of paramere fused with phallic sheath or reduced........................................................ 8

- Base of paramere a clearly demarcated separate sclerite....................................................... 9

8. Pedicel shorter than scape. Paramere widening distally, basally originating distal to broadest point of basiphallus.................................................................................... P. vestita Vaillant & Withers, 1993

- Pedicel longer than scape. Paramere narrowing distally, basally originating at broadest point of basiphallus........................................................................................... P. pseudocalcilega Krek, 1972

9. Median indentation of phallic sheath reaching broadest point of basiphallus. Paramere broadening distally (Vaillant 1978, plate LXVII, fig. 4)................................................................. P. pingarestica Vaillant, 1978

- Median indentation of phallic sheath reaching base of phallomeres. Paramere narrowing distally (Vaillant & Withers 1993, fig. 16)........................................................................... P. calcilega Feuerborn, 1923

10. Narrow part of gonostylus shorter than or equal to broad basal part............................................. 11

- Narrow part of gonostylus longer than broad basal part....................................................... 12

11. Basal part of gonostylus wider than gonocoxite. Paramere apically T-shaped (Vaillant 1978, plate LXVI, fig. 6). Surstylus with five tenacula....................................................................... P. bosniaca Krek, 1967

- Basal part of gonostylus as wide as gonocoxite. Paramere apically V-shaped c (Vaillant 1978, plate LXVI, fig. 3). Surstylus with six tenacula................................................................ P. maroccana Vaillant, 1955

12. Gonostylus comparatively straight....................................................................... 13

- Gonostylus distinctly curved............................................................................ 14

13. Parabasal process of gonocoxite broadly triangular (Vaillant 1978, plate LXII, fig. 6). Epandrium longer than wide. Paramere originating distal to origin of phallomeres................................................ P. egeica Vaillant, 1978

- Parabasal process of gonocoxite curved, tapering (Vaillant 1978, plate LXII, fig. 3). Epandrium about as wide as long. Paramere originating at about same level as phallomeres.................................. P. tenuistylis Vaillant, 1978

14. Phallic sheath with elongate projections at distolateral corners. Broad basal part of gonostylus ca one fifth length of gonostylus (Vaillant 1978, plate LXII, fig. 4).................................................... P. barbarica Vaillant, 1955

- Phallic sheath without projections. Broad basal part of gonostylus more than one third of total length of gonostylus....... 15

15. Median concavity of gonostylus angular (Vaillant 1978, plate LXII, fig. 1). Base of paramere as broad as distal part of distiphallus (Vaillant 1978, textfig. 479)................................................ P. trifasciata (Meigen, 1804)

- Median concavity of gonostylus smoothly curved (Vaillant 1978, plate LXII, fig. 2). Base of paramere broader than distal part of distiphallus (Vaillant 1978, plate LXVI, fig. 5)....................................... P. arvernica Vaillant, 1978