Pagastia Oliver, 1959

Makarchenko, Eugenyi A., 2019, Review of the genus Pagastia Oliver (Diptera: Chironomidae: Diamesinae) from North America, with description of P. (P.) subletteorum sp. nov., Zootaxa 4664 (1), pp. 115-128 : 127

Key to the known species of Pagastia Oliver of Holarctic region

Males

1. Eyes hairy. Aedeagal lobes reduced (subgenus Hesperodiamesa Sublette ). Basal lobe of gonocoxite small..................................................................................... P. (H.) sequax ( Garrett, 1925) ( Fig. 18 )

- Eyes bare or pubescent. One or two aedeagal lobes present (subgenus Pagastia Oliver ). Basal lobe of gonocoxite large.... 2

2. Both median and lateral aedeagal lobes present. AR 2.5-4.2.................................................... 3

- Only lateral aedeagal lobe present. AR 1.0–2.42............................................................. 6

3. Antepronotum with dorsal and lateral setae in widely separated groups. Median aedeagal lobe digitated and widest in distal part................................................................................................ 4

- Antepronotum completely covered with setae. Median aedeagal lobe widest medially, then tapering abruptly and with the apex forming a sharp hook.......................................... P. (Pagastia) partica ( Roback, 1957) ( Figs.16–17 )

4. Gonostylus subapical with "heel".................... P. (P.) nivis (Tokunaga, 1936) ( Makarchenko 2006, Fig. 180, 5–10)

- Gonostylus subapical without "heel"...................................................................... 5

5. Apex of the gonostylus is angled.............. P. (P.) orientalis (Tshernovskij, 1949) ( Makarchenko 2006, Fig. 181, 1–5)

- Apex of the gonostylus is broadly rounded............................................................................................. P. (P.) altaica Makarchenko, Kerkis et Ivanchenko, 1997 ( Makarchenko et al. 1997, Fig. 1 )

6. Anal point absent. AR 1.0–1.2. Alula of wing with some setae............. P. (P.) subletteorum sp. nov. ( Figs. 1–6 , 19–20 )

- Anal point present. AR 1.54–2.42. Alula without setae........................................................ 7

7. Anal point almost parallel-sided in dorsal view; lateral aedeagal lobe tapering to thin apex........................... 8

- Anal point tapering to apex; lateral aedeagal lobe wide in distal part............................................. 9

8. Anal point with rounded apex and without apical peg.................... P. (P.) orthogonia Oliver, 1959 ( Figs. 7–13 , 21 )

- Anal point with pointed apical peg. AR 1,56–1.75............. P. (P.) hidakamontana Endo, 2004 ( Endo 2004, Figs. 1–6 )

9. Anal point narrow, tapering to pointed apex, without apical peg; gonostylus in basal part with outer angle-shaped projection. AR 2.18–2.42................ P. (P.) tianmumontana Makarchenko et Wang, 2017 ( Makarchenko &Wang 2017, Figs. 17 )

- Anal point widest in basal part and thin apically, pointed and often with apical peg; gonostylus without outer basal projection. AR 1.81–2.10............................... P. (P.) lanceolata (Tokunaga, 1936) ( Makarchenko 2006, Fig. 180, 1–4)

Figures

FIGURES 14–18. Pagastia (P.) partica (Roback) (14–17) and P. (H.) sequax (Garrett) (lectotype) (18), males. 14, 18, hypopygium in dorsal view; 15, gonostylus; 16, aedeagal lobes; 17, part of hypopygium without tergite IX. MAl, median aedeagal lobe. Scale bars: 50 µm.

FIGURES 1–6. Pagastia (P.) subletteorum sp. nov., male. 1, hypopygium in dorsal view; 2, inner structures of hypopygium; 3– 4, gonostylus in various aspects; 5, part of tergite IX; 6, gonocoxite and gonostylus in dorsal view. Bl, basal lobe of gonocoxite; LAl, lateral aedeagal lobe; Pha, phallapodeme; TSa, transverse sternapodeme. Scale bars: 50 µm.

FIGURES 19–20. Pagastia (P.) subletteorum sp. nov., male. 19, hypopygium in dorsal view; 20, gonostylus.

FIGURES 7–13. Pagastia (P.) orthogonia Oliver, males from Alaska (holotype) (7–9) and South Dakota (10–13). 7, 10, hypopygium in dorsal view; 8, gonocoxite and gonostylus in ventral view; 9, inner structures of hypopygium; 11, gonostylus; 12, anal point; 13, gonocoxite and gonostylus in dorsal view. Scale bars: 50 µm.

FIGURES 21–25. Pagastia (P.) orthogonia Oliver from South Dakota (21) and P. (P.) partica (Roback) (22–25), males. 21, 23, 25, hypopygium in dorsal view; 22, part of hypopygium without tergite IX; 24, anal point.