Clastobasis ainuorum, Kurina, 2020

Kurina, Olavi, 2020, Three new species and new records of Clastobasis Skuse (Diptera: Mycetophilidae) from Japan and the Kuril Islands, Zootaxa 4810 (3), pp. 589-600 : 590-591

Key to the Palearctic species of Clastobasis based on characters of male terminalia

1. Medioventral flange of the gonocoxite club-shaped, with a line or aggregation of short spines on apical portion (e.g. Figs 3C , 4C ) … ............................................................................................. 3

- Medioventral flange of the gonocoxite sickle-shaped, with spine-like setae along whole medial margin (e.g. Fig. 2C )....… 2

2. Medial margin of medioventral flange of the gonocoxite with short, blunt and apically slightly bent setae, and with 9–10 strong medially directed pointed setae along the whole margin; apicodorsal margin of gonocoxite without medially directed lobe ( Fig. 2B, C ); cerci elongated, extending over apex of tergite 9, with short blunt spines on apicoventral surfaces ( Fig. 2 A–C) …...................................................................... C. ainuorum sp. n. [Kuril Islands: Iturup]

- Medioventral flange of the gonocoxite only with short pointed setae; apicodorsal margin of gonocoxite with medially directed black and apically serrated small lobe; cerci without spines on apicoventral surface ( Zaitzev 1994: figs 81-1, 5)..................................................................... … C. gussakowskii Zaitzev [ Russia: Primorsky krai]

3. Short spines on medioventral flange of the gonocoxite stout, in a distinct single line along apicomedial and apical margin... ................................................................................................... 4

- Short spines on medioventral flange of the gonocoxite thin, in an apicomedial polystichous aggregation ….............. 5

4. Tergite 9 apically rounded ( Fig. 3 A–C); gonostylus posteriorly tripartite, with lateral lobes crescent-shaped in ventral view ( Figs 3D, E , 5B ); aedeagal guide with delimited aggregation of 4–5 strong setae directed laterad ( Fig. 3C ) …...................................................................................... C. kanabo sp. n. [ Japan, Honshū]

- Tergite 9 apically angular ( Fig. 4 A–C); gonostylus posteriorly bipartite, medial lobe with an additional saddle-shaped sub-lobe dorsally ( Fig. 4D, E ); aedeagal guide without delimited aggregation of setae ( Fig. 4C ) … C. menguali sp. n. [ Japan, Honshū]

5. Thorax laterally yellow to light brown; medioventral flange of the gonocoxite with an aggregation of small spines apicomedi- ally; gonostylus without spines …........................................................................ 6

- Thorax laterally black; medioventral flange of the gonocoxite with an aggregation of ca 20 short and stout spines apicodorsally ( Sasakawa 2005: fig. 9); gonostylus with a line of ca 30 spines ( Sasakawa 2005: fig. 11) …............................................................................................... C. serrulata Sasakawa [ Japan, Honshū]

6. Apicomedial portion of medioventral flange of the gonocoxite in addition to an aggregation of small spines with three long and twisted megasetae ( Chandler 2001: figs 18, 20); tergite 9 not divided, with two apical stout spines ( Fig. 5E ; Chandler 2001: figs 18, 20) ….............................................................. C. loici Chandler [Trans-Palaearctic]

- Apicomedial portion of medioventral flange of the gonocoxite with an aggregation of small spines only; tergite 9 divided....................................................................................................… 7

7. Medioventral flange of the gonocoxite in lateral view angular, drawn into evenly tapering apicodorsal lobe, with marginal polystichous zone of small spines ( Chandler 2001: figs 15, 17) …..................... C. alternans (Winnertz) [Europe]

- Medioventral flange of the gonocoxite in lateral view smoothly curved dorsad, drawn into expanding apicodorsal lobe, with small spines over whole medial surface ( Fig. 5D ; Zaitzev 2017: figs 1–4).............................................................................................. … C. subalternans Zaitzev [Kuril Islands; Japan, Honshū]

Figures

FIGURE 2. Clastobasis ainuorum sp. n., male terminalia. A. Dorsal view of gonocoxite and tergite 9. B. Ventral view of api- cal half, left gonostylus detached. C. Ventral view, left gonostylus detached. D. Gonostylus, interior view. E. Closer view of aedeagal guides and aedeagal complex, ventral view.Abbreviations: aed = aedeagus; aed gd = aedeagal guide; cerc = cercus; gc = gonocoxite; gc mvf = medioventral flange of gonocoxite; gc pll = posterolateral lobe of gonocoxite; gst = gonostylus; hyp = hypoproct; tg 9 = tergite 9. Scale bar = 0.1 mm (A, B, C, E) and 0.05 mm (D).

FIGURE 3. Clastobasis kanabo sp. n., male terminalia. A. Dorsal view of gonocoxite and tergite 9. B. Ventral view of apical half, left gonostylus detached. C. Ventral view, left gonostylus detached. D. Gonostylus, ventral view. E. Gonostylus, interior view. Abbreviations: aed gd = aedeagal guide; cerc = cercus; tg 9 = tergite 9. Scale bar = 0.1 mm (A, B, C) and 0.05 mm (D, E).

FIGURE 4. Clastobasis menguali sp. n., male terminalia. A. Dorsal view of gonocoxite and tergite 9. B. Ventral view of apical half, left gonostylus detached. C. Ventral view, left gonostylus detached. D. Gonostylus, ventral view. E. Gonostylus, interior view. Scale bar = 0.1 mm (A, B, C) and 0.05 mm (D, E).

FIGURE 5. Male terminalia of East Palaearctic Clastobasis species, lateral view. A. C. menguali sp. n. B. C. kanabo sp. n. C. C. ainuorum sp. n. D. C. subalternans Zaitzev, 2017. E. C. loici Chandler, 2001. F. C. loici, gonostylus. G. C. loici, quadrangular appendage with apical comb. Abbreviations: aed gd = aedeagal guide; cerc = cercus; gc = gonocoxite; gc vmf = medioventral flange of gonocoxite; gc pll = posterolateral lobe of gonocoxite; gst = gonostylus; tg 9 = tergite 9. Scale bar = 0.1 mm.