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.