Pseudexechia

Kjaerandsen, Jostein, 2009, The genus Pseudexechia Tuomikoski re-characterized, with a review of European species (Diptera: Mycetophilidae), Zootaxa 2056, pp. 1-45 : 12-13

Key to European males of Pseudexechia

1 Terminalia large, stout ( Fig. 6 A); dorsal branch of the gonostylus with a characteristically smooth whitish apex; ventral branch forming a thin plate shaped more or less like a spatula ( Fig. 6 B); hypandrial lobe heavily sclerotized, bud-like by elaborate folding, triangular to subrectangular ( Fig 6 A).......................................................................... 2

- Terminalia more slender ( Fig. 14 A), with elongated dorsal and ventral branches of the gonostylus ( Fig. 14 B); hypandrial lobe narrow rectangular, forming parallel branches medially ( Fig. 14 A) ................................. trivittata group 8

2 Median ocellus small, but distinctly present ( Fig. 4 A); vein R4+5 distinctly downcurved (C> D in Fig. 3A); hypandrial lobe stout, subrectangular ( Fig. 6 A) ........................................................................................ trisignata group 3

- Median ocellus absent or at most tiny and vestigial; vein R4+5 almost straight (C ≤ D in Fig. 3B&D); hypandrial lobe

conic, triangular ( Fig. 9 A) or enlarged and diverging apically ( Fig. 11 D) ...................................... canalicula group 5 3 A dull brown species with a distinct greyish dusting ( Fig. 2 A); hypandrial lobe with rounded corners ( Fig. 6 A); ventral branch of gonostylus with angular basodorsal corner making the spatula broadest basally ( Fig. 6 B); smooth whitish tip of dorsal branch of gonostylus evenly thick ( Fig. 6 B)............... Pseudexechia trisignata ( Edwards, 1913)

- Moderately to distinctly bi-coloured species without greyish dusting; hypandrial lobe sharply pointed apically ( Fig. 7 A); ventral branch of gonostylus without angular basodorsal corner; smooth whitish tip of dorsal branch of gonostylus slightly dilated or constricted ............................................................................................................................... 4

4 Broad pale band along whole margin mesonotum; ventral branch of gonostylus forming small, symmetric and round spatula ( Fig. 7 B); smooth whitish tip of dorsal branch of gonostylus slightly constricted ( Fig. 7 B) ............................ .......................................................................................................... Pseudexechia pectinacea ( Ostroverkhova, 1979)

- Without or at most narrow pale band along margin of mesonotum; ventral branch of gonostylus forming large, asymmetric spatula that is broadest apically ( Fig. 8 B); smooth whitish tip of dorsal branch of gonostylus slightly dilated ( Fig. 8 B) ......................................................................................................... Pseudexechia tuomikoskii sp. n.

5 Larger species, distinctly bi-coloured in dark greyish brown and yellow, with sharply defined mesonotal stripes ( Fig. 2 B) ............................................................................................................................................................................... 6

- Smaller species, weakly bi-coloured to dull brown, with indistinct or fused mesonotal stripes ................................. 7

6 Gonostylus large, exposed ( Fig. 9 A); dorsal branch distinctly dilated apically ( Fig. 9 B); ventral branch forming large, slightly asymmetrical spatula ( Fig. 9 B) ......................................... Pseudexechia canalicula ( Johannsen, 1912)

- Gonostylus small, retracted ( Fig. 10 A); dorsal branch not dilated apically ( Fig. 10 B); ventral branch forming narrow, angular boot-shaped spatula ( Fig. 10 B) ..................................................... Pseudexechia aurivernica Chandler, 1978

7 Hypandrial lobe enlarged, diverging apically ( Fig. 11 A&D); dorsal branch of gonostylus apically strongly dilated, campanulate ( Fig. 11 B); dorsointernal branch small ( Fig. 11 B); ventral branch narrow, angular boot-shaped ( Fig. 11 B) ........................................................................................... Pseudexechia monica Kjaeandsen & Chandler, 2006

- Hypandrial lobe not enlarged, conic triangular ( Fig. 12 A); dorsal branch of gonostylus apically dilated, but not campanulate ( Fig. 12 B); dorsointernal branch large ( Fig. 12 B); ventral branch forming medium sized spatula with acute angled apicodorsal corner ( Fig. 12 B)............................................................ Pseudexechia parallela ( Edwards, 1925)

8 Dorsal branch of gonostylus subrectangular, with sharply truncated, whitish tip ( Fig 13 A&B); dorsointernal branch forming narrow, elongated lamellate fan ( Fig. 13 B); hypoproct reduced, hyaline ( Fig. 13 C) ....................................... ......................................................................................... Pseudexechia latevittata Chandler & Blasco-Zumeta, 2001

- Dorsal branch of gonostylus oblong to lanceolate, without sharply truncated, whitish tip ( Fig. 14 A&B); dorsointernal branch reduced to hyaline knob basally on dorsal branch ( Fig. 14 B); hypoproct sclerotized, pointed ( Fig. 14 C). ...................................................................................................................................................................................... 9

9 A distinctly bi-coloured species in dark greyish brown and yellow, with sharply defined thoracic stripes and triangular pale bands on abdominal tergites; dorsal branch of gonostylus shorter and smaller than ventral branch which has medial surface covered with setae and no brush apically ( Fig. 14 B) ........ Pseudexechia tristriata Stackelberg, 1969

- A dull brown species with fused, hardly discernible thoracic stripes and indistinct, narrow (if any) pale bands on abdominal tergites; dorsal branch of gonostylus longer than ventral branch which has medial surface devoid of setae but a narrow brush of strong setae apically ( Fig. 15 B) ................................... Pseudexechia trivittata ( Staeger, 1840)

Figures

FIGURE 2. Habitus photos of Pseudexechia. — A. P. trisignata (Edwards, 1913) in lateral view, a dull brown species with a distinct greyish dusting, with fused thoracic stripes and narrow apical pale bands on abdomen. — B. P. aurivernica Chandler, 1978 in lateral view, a distinctly bi-coloured species in dark greyish brown and yellow, often with a reddish tinge, with distinct thoracic stripes and with large, triangular apical pale bands on abdomen — C. P. canalicula (Johannsen, 1912) in dorsal view, yet another bi-coloured species in greyish brown and yellow with distinct thoracic stripes.

FIGURE 4. Morphology of Pseudexechia [A – D + F – J = P. trisignata (Edwards, 1913), E = P. pectinacea (Ostroverkhova, 1979)]. — A. Head in dorsal view. — B. Antenna, dorsal view. — C. Antenna, lateral view — D. Segment III – V of maxillary palp. — E. Face enlarged. — F. Thorax, lateral view. — G. Fore tarsus V. — H. Mid tarsus V. — I. Hind tarsus V. — J. Apex of hind tibia, medial view. Abbreviations: anepist = anepisternum; clyp = clypeus; cx 1 = forecoxa; cx 2 = midcoxa; cx 3 = hindcoxa; emp = empodium; fc = face; flag I = first flagellar segment; flag II = second flagellar segment; fr fur = frontal furrow; fr tub = frontal tubercle; htl = halter; ltg = laterotergite; m oc = medial ocellus; mtg = mediotergite; proepist seta = proepisternal seta; sc = scutum; sctl = scutellum; sens pit = sensory pit; t comb = tibial comb.

FIGURE 6. Pseudexechia trisignata (Edwards, 1913). — A. Male terminalia, ventral view. — B. Male gonostylus, internal view. — C. Male tergite IX and cerci, dorsal view. — D. Female terminalia, lateral view.

FIGURE 7. Pseudexechia pectinacea (Ostroverkhova, 1979). — A. Male terminalia, ventral view. — B. Male gonostylus, internal view, enlarged. — C. Male tergite IX and cerci, dorsal view. — D. Female terminalia, lateral view.

FIGURE 8. Pseudexechia tuomikoskii sp. n. — A. Male terminalia, ventral view. — B. Male gonostylus, internal view. — C. Male tergite IX and cerci, dorsal view. — D. Female terminalia, lateral view.

FIGURE 9. Pseudexechia canalicula (Johannsen, 1912). — A. Male terminalia, ventral view. — B. Male gonostylus, internal view, enlarged. — C. Male tergite IX and cerci, dorsal view. — D. Female terminalia, lateral view.

FIGURE 10. Pseudexechia aurivernica Chandler, 1978. — A. Male terminalia, ventral view. — B. Male gonostylus, internal view, enlarged. — C. Male tergite IX and cerci, dorsal view. — D. Female terminalia, lateral view.

FIGURE 11. Pseudexechia monica Kjaerandsen & Chandler, 2006. — A. Male terminalia, ventral view. — B. Male gonostylus, internal view, enlarged. — C. Male tergite IX and cerci, dorsal view. — D. Hypandrial lobe, ventral view, enlarged.

FIGURE 12. Pseudexechia parallela (Edwards, 1925). — A. Male terminalia, ventral view. — B. Male gonostylus, internal view, enlarged. — C. Male tergite IX and cerci, dorsal view. — D. Female terminalia, lateral view.

FIGURE 13. Pseudexechia latevittata Chandler & Blasco-Zumeta, 2001. — A. Male terminalia, ventral view. — B. Male gonostylus, internal view, enlarged. — C. Male tergite IX and cerci, dorsal view. — D. Female terminalia (redrawn from Chandler & Blasco-Zumeta 2001), lateral view.

FIGURE 14. Pseudexechia tristriata (Stackelberg, 1969). — A. Male terminalia, ventral view. — B. Male gonostylus, internal view. — C. Male tergite IX and cerci, dorsal view. — D. Female terminalia, lateral view.

FIGURE 15. Pseudexechia trivittata (Staeger, 1840). — A. Male terminalia, ventral view. — B. Male gonostylus, internal view. — C. Male tergite IX and cerci, dorsal view. — D. Female terminalia, lateral view.