Hyadina, Haliday in Curtis, 1837

Mathis, Wayne N. & Zatwarnicki, Tadeusz, 2019, Revision of the Shore-fly Genera Parahyadina Tonnoir and Malloch and New Zealand Hyadina Haliday (Diptera: Ephydridae), Zootaxa 4623 (3), pp. 401-440 : 409

Key to Species of Hyadina and Parahyadina

1. Lateroclinate fronto-orbital seta weakly developed, basal diameter much reduced in comparison to basal diameters of vertical setae............................................................................................... 2

- Lateroclinate fronto-orbital seta well developed, basal diameter comparable or only slightly reduced in comparison to basal diameters of vertical setae.............................................................................. 3

2. Dorsocentral postsutural seta 1 with several dorsocentral setulae; male tergites 3–5 with ventrolateral margin shallowly and bluntly rounded.......................................................................... H. breva , sp. nov.

- Dorsocentral postsutural setae 2 with several dorsocentral setulae; male tergites 3–5 with anterior margin extended ventrolaterally as a pointed, well-sclerotized process.................................................. P. edmistoni , sp. nov.

3. Costal section II equal in length or longer than costal section III................................................ 4

- Costal section II shorter than costal section III.............................................................. 8

4. Wings amber......................................................................................... 5

- Wings hyaline........................................................................................ 6

5. Aedeagus in lateral view sickle shaped ( Fig. 16 ); hypandrial-gonal structure longer than wide in ventral view ( Fig. 15 ), apical extensions of gonites digitiform.............................................................. P. atra , sp. nov.

- Aedeagus in lateral view more or less rectangular ( Fig. 10 ); hypandrial-gonal structure wider than long in ventral view ( Fig. 9 ), apical extensions irregularly bifurcate...................................................... P. angusta , sp. nov.

6. Surstylar midheight bearing 5–6 setulae; aedeagus in lateral view shoe-like with tapered and narrow “toe”; gonite in lateral view ( Fig. 22 ) relatively narrow, straight throughout length.................................... P. bifurcata , sp. nov.

- Surstylar midheight bearing 2 setulae; aedeagus in lateral view more or less rectangular; gonite in lateral view L-shaped, apical portion more robust ( Fig. 52 )............................................................................ 7

7. Shape of hypandrium-gonite in ventral view ( Fig. 51 ) more or less quadrate with corners extended as thumb-like process posteriorly and as shallowly bifurcate, broad process anterolaterally, anterior margin concave....................................................................................................... P. lacustris Tonnoir and Malloch

- Shape of hypandrium-gonite in ventral view ( Fig. 25 ) tubular with lateral extension at 90° angle and with paired apical, digitiform extensions medially that bear 2 apical tubercles (Chatham Islands).............................. P. bulla , sp. nov.

8. Male tergites 3–5 with anterior margin extended ventrolaterally as a pointed, well-sclerotized process; male tergite 5 tucked obliquely ventrad from plane of tergite 4................................................... P. edmistoni , sp. nov.

- Male tergites 3–5 with ventrolateral margin shallowly and bluntly rounded; male tergite 5 extended posteriorly in same plane as tergite 4........................................................................................... 9

9. Postsutural scutum without distinct, longitudinal vittae between acrostichal setae and dorsocentral setae; fronto-orbital setae and lateral vertical seta identical in length and basal width. Surstylus conspicuously tapered, apex narrowly rounded............................................................................................. P. irwini , sp. nov.

- Postsutural scutum with distinct, longitudinal vittae in rows between acrostichal setae and dorsocentral setae............ 10

10. Fronto-orbital seta subequal in length to lateral vertical seta. Surstylus in posterior view ( Fig. 39 ) tapered to narrowly rounded apex................................................................................. P. hennigi , sp. nov.

- Fronto-orbital setae shorter than lateral vertical seta. Surstylus in posterior view ( Figs. 29 , 55 ) somewhat rectangular with apex very shallowly bilobed................................................................................ 11

11. Medial and lateral lobes of surstylar apex about equal in length (best seen in posterior view); gonite in ventral view ( Fig. 57 ) with large, tapered, lateral process......................................................... P. latistylis , sp. nov.

- Lateral lobe of shallow surstylar bifurcation longer than medial lobe or angle; gonite in ventral view ( Fig. 21 ) with ventrally oriented, deeply bifurcate process.......................................................... P. debilis , sp. nov.

Figures

FIGURES 13–16. Parahyadina atra sp. nov. (male; New Zealand. South Island. CO: Danseys Pass). 13. Epandrium, cerci, and surstyli, posterior view. 14. Same, lateral view. 15. Internal structures of male terminalia, ventral view. 16. Same, lateral view (scale bar = 0.1 mm).

FIGURES 7–10. Parahyadina angusta sp. nov. (male; New Zealand. South Island. OL. Queenstown). 7. Epandrium, cerci, and surstyli, posterior view. 8. Same, lateral view. 9. Internal structure of male terminalia, ventral view. 10. Same, lateral view (scale bar = 0.1 mm).

FIGURES 19–22. Parahyadina bifurcata sp. nov. (male; New Zealand. South Island. FD: Monowai River). 19. Epandrium, cerci, and surstyli, posterior view. 20. Same, lateral view. 21. Internal structures of male terminalia, ventral view. 22. Same, lateral view (scale bar = 0.1 mm).

FIGURES 49–52. Parahyadina lacustris Tonnoir and Malloch (male; Whangaroa (rocky beach)). 49. Epandrium, cerci, and surstyli, posterior view. 50. Same, lateral view. 51. Internal structures of male terminalia, ventral view. 52. Same, lateral view (scale bar = 0.1 mm).

FIGURES 23–26. Parahyadina bulla sp. nov. (male; New Zealand. Chatham Island. Tennants Lake). 23. Epandrium, cerci, and surstyli, posterior view. 24. Same, lateral view. 25. Internal structures of male terminalia, ventral view. 26. Same, lateral view (scale bar = 0.1 mm).

FIGURES 39–42. Parahyadina hennigi sp. nov. (male; New Zealand. South Island. CO: Danseys Pass). 39. Epandrium, cerci, and surstyli, posterior view. 40. Same, lateral view. 41. Internal structures of male terminalia, ventral view. 42. Same, lateral view (scale bar = 0.1 mm).

FIGURES 29–32. Parahyadina debilis sp. nov. (male; New Zealand. South Island. OL: Mararoa River (25 km E Te Anau)). 29. Epandrium, cerci, and surstyli, posterior view. 30. Same, lateral view. 31. Internal structures of male terminalia, ventral view. 32. Same, lateral view (scale bar = 0.1 mm).

FIGURES 55–58. Parahyadina latistylis sp. nov. (male; New Zealand. North Island. TO: Tokaanu). 55. Epandrium, cerci, and surstyli, posterior view. 56. Same, lateral view. 57. Internal structures of male terminalia, ventral view. 58. Same, lateral view (scale bar = 0.1 mm).