1. Zygomyia immaculata n. sp. Tonn.

♂ Head brown; palpi orange; first five antennal segments orange, the rest gradually darker, flagellar segments about twice as long as wide. Thorax brown, mesonotum slightly ochreous on sides anteriorly and in front of scutellum; pubescence of disc partly yellowish, partly black, and not arranged regularly. Abdomen brown rather dull; legs entirely yellow; middle tibiae with four dorsal, three external, three ventral (the middle one longer), and two to three internal bristles. Wings greyish somewhat darker anteriorly, unmarked but for a very slight and indistinct shadow on r-m. Halteres yellow.

Length of body, 3 mm.; wing, 3½ mm.

Type: Otira (Tonn.), 9th Feb., 1922, in Cawthron Inst. coll.

Paratype: Mt. Arthur (Tonn.), 20th Dec., 1921.

The number of ventral bristles on the middle tibiae is variable.

2. Zygomyia similis n. sp. Tonn.

♀ Head brown; palpi dark; antennae brown with scape and base of third segment orange. Thorax ferrugineous-brown, the notum with slight cinereous reflection and short, equal and regularly arranged pubescence on disc. Abdomen brown, lamellae dark. Legs completely yellow; middle tibiae with five dorsal, three external, five ventral (of unequal length), and six internal bristles. Wings as in Z. immaculata, without markings. Halteres yellow.

Length of body, 3 mm.; wing, 3½ mm.

Type: Waiho (Tonn.), 17th Jan., 1922.

3. Zygomyia bifasciata n. sp. Tonn.

♂ Head brownish, antennae orange on their first third, then gradually darker, flagellar segments not twice as long as broad; palpi

dark orange. Mesonotum and scutellum dark orange, the rest of thorax brown. Abdomen rather shining brown, hypopygium orange; pubescence of body brown. Legs entirely yellow; middle tibiae with five dorsal, three external, three ventral, and three internal (one long) bristles. Wings with central fascia on r-m and fM not extending in costal cell but prolonged below M₄; a further transverse rather wide band under last part of R₁, this band being only half as wide in cell M₃; apex of wing clear. Halteres yellow.

♀ Similar to male but the two dark fasciae of wings touching along the branches of M; cell M₃ is therefore dark on its first two-third and includes there a small roundish clear spot.

Length of body, 2½ mm.; wing, 3 mm.

Type: Lake Brunner (Tonn.), 5th Feb., 1922, in Cawthron Inst. coll.

Allotype: Maitai Valley, Nelson (Tonn.), 17th Mar., 1922.

Paratypes: Kaikoura, 22nd Feb., 1922; Khandallah, 30th Nov., 1921; Waiho, 30th Jan., 1922 (Tonn.).

Specimens in Brit. Mus.: Ohakune (Harris).

4. Zygomyia bivittata n. sp. Tonn. (Fig. 88.)

♂ Head, thorax and abdomen blackish-brown with slight cinereous reflection in certain positions; pubescence yellowish. The first four segments of antennae orange, the rest gradually darker, flagellar segments about twice as long as wide; palpi orange. Legs yellowish; tip of coxae darkish, tip of hind femora rather broadly black, tip of middle femora and posterior tibiae very slightly darkened. Middle tibiae with five dorsal, three external, two to four (only one long) ventral, and two to three internal bristles. Wings subhyaline with dark markings as follow: a transverse zig-zag narrow band extending from costa on r-m, fM and from there fainter, towards hind-border of wing, a very wide subapical band leaving only tip of cell R₅ and M₃ clear. Sc is rather long and extends to middle of basal cell. Halteres with yellow stem and dark knob.

Length of body, 3 mm.; wing, 3½ mm.

Type: Mt. Arthur, 26th Dec., 1921 (Tonn.), in Cawthron Inst. coll.

Allotype Kaitouna, 19th Feb., 1922.

Specimen in Brit. Mus.: Leith Valley (Howes).

5. Zygomyia obsoleta n. sp. Tonn.

♀ Head, thorax and abdomen completely brown; base of antennae and palpi yellow. Anal lamellae dark. Legs entirely yellow. Middle tibiae with four dorsal, two external, one ventral, and one to two internal bristles. Wing with dark markings very faint and arranged as follow: one spot on r-m and fM and an apical shadow distinct only on anterior border of distal half of wing. Halteres entirely yellow.

This species comes rather near Z. apicalis but the markings are much fainter and the apical one does not extend on the posterior half of the wing.

Length of body and wing, 2 mm.

Type: Waiho (Tonn.), 20th Jan., 1922.

6. Zygomyia costata n. sp. Tonn.

♀ Head and appendages brown; antennae paler at base, segments of flagellum conspicuously shorter than broad, the whole antenna not much longer than head. Thorax dull brownish-black, shoulders orange, pubescence of notum yellowish. Abdomen rather shining, brownish black pubescence of margin of segments yellow, the rest dark; anal lamellae orange. Legs yellow, hind femora broadly black at tip middle tibiae, with four dorsal, two external, two ventral, and one internal bristles. Wings rather broad with whole anterior border except the very base uniformly brownish, this shadow extending also on posterior part of distal half of membrane but being there rather faint and including a clear spot in cell R₅ and M₃, this spot not touching vein R₅. r-m exceedingly short. Halteres whitish.

Length of body and wing, 2 mm.

Type: Nelson (Tonn.), 1st Nov., 1923, in Cawthron Inst. coll.

7. Zygomyia nigrohalterata n. sp. Tonn. (Fig. 292.)

♂ Head and appendages brown, base of antennae paler; segments of flagellum about twice as long as broad. Thorax dull brown, slightly ferrugineous. Abdomen dark brown; hypopygium orange. Pubescence of body dark. Legs completely yellow; middle tibiae with four dorsal, three external, four ventral, and five internal (one long) bristles. Wing subhyaline with a darkish spot on r-m and fM; the apical half of wing uniformly brownish. Halteres with yellow stem and dark knob.

♀ Similar to male; antennae darker at the base; anal lamellae dark.

Length of body and wing, 2½ mm.

Type: Mt. Arthur, Dec., 1921, in Cawthron Inst. coll.

Allotype and paratypes: idem.

The chaetotaxy of the middle tibiae is variable; it is sometimes: 4. 2. 3. 4–5.

8. Zygomyia grisescens n. sp. Tonn.

♂ Head brown, palpi black, rather short; antennae brown with scape orange, segments of flagellum, as an average, three times as long as wide. Thorax dull ferrugineous brown with brownish-yellow adpressed regularly arranged pubescence on disc of notum. Abdo men brown, hypopygium with two long dorsal lamellae. Legs yellowish tip of posterior coxae, base of posterior femora below and tip of posterior tibiae slightly darkened. Middle tibiae with three dorsal, three external, two ventral, and four internal bristles. Wing nearly completely smoky with base clear and a clear space after r-m between R₁ and M₃. Halteres yellow.

Length of body, 3¼ mm.; wing, 3¾ mm.

Type: Mt. Arthur (Tonn.), 21st Dec., 1921, in Cawthron Inst. coll.

One specimen in Brit. Mus.: Mt. Grey (Campbell), 23rd Feb., 1924; the formula of the middle tibiae of this specimen is different: 5. 3. 4–5. 4–5., the structure of the hypopygium is, however, exactly similar.

9. Zygomyia ruficollis n. sp. Tonn. (Fig. 93.)

♀ Head orange basal third of antennae orange, the rest gradually darker, segments of flagellum about twice as long as wide; palpi dark. Thorax completely orange-yellow. Abdomen brown with hind-border of segments yellow, chiefly on sides; lamellae dark orange. Legs yellow, tip of hind tibiae dark. Mid-tibiae with five dorsal, four external three ventral and four internal bristles. Wing with a central fascia extending from costa over r-m, fM and from there exceedingly faint to posterior margin of wing; apical two-fifth entirely dark but more intensely towards anterior border. Halteres yellow with base of knob dark.

Length of body and wing, 3 mm.

Type: Wellington (Tonn.), 1st Dec., 1921, in Cawthron Inst. coll.

Paratype: Christchurch, Horseshoe Lake (Heighway), 17th Sept., 1924.

10. Zygomyia nigriventris n. sp. Tonn. (Fig. 302.)

♂ Head, thorax and abdomen dark brown; mesonotum somewhat ferrugineous; pubescence dark. Palpi short, brown; antennae moderately long, flagellar segments not twice as long as wide; scape dark orange, the rest dark. Hypopygium according to fig. 302. Legs entirely yellow; middle tibiae with five dorsal, two to three external, three ventral, and three to four internal bristles. Wings with a transverse zig-zag band from costa across r-m and fM to posterior border of wing but much fainter below M₃ apical two-fifth completely brown and more strongly anteriorly. Halteres yellow.

♀ Similar to male, anal lamellae dark.

Length of body, 2 mm.; wing, 2½ mm.

Type: Mt. Arthur, 26th Dec., 1921, in Cawthron Inst. coll.

Allotype and paratypes: idem.

11. Zygomyia brunnea n. sp. Tonn. (Fig. 303.)

♂ Head and appendages brown, antennae scarcely paler at base. Thorax brown, mesonotum slightly ferrugineous with cinereous sides in certain light. Abdomen brown; hypopygium as in fig. 303. Pubescence of body yellowish. Legs yelow, tip of posterior coxae and base of posterior femora below brownish. Middle tibiae with four to five dorsal, two external, two to three ventral and three internal bristles. Wing exactly as in the preceding species. Halteres yellow.

♀ Similar to male, anal lamellae dark.

Length of body and wing, 2½ mm.

Type: Mt. Arthur, 22nd Dec., 1922, in Cawthron Inst. coll.

Allotype: idem.

Paratypes numerous from many parts of N.Z.

This is one of the most common species of the genus. It can be easily confused with the preceding one from which it differs only by some detail of structure of the hypopygium.

12. Zygomyia apicalis n. sp. Tonn.

♂ Head, thorax and abdomen completely dark brown, the mesonotum a little lighter; pubescence of body dark. Palpi and antennae entirely dark Antennae moderately long, flagellar segments one and

a half times as long as wide. Hypopygium with two rather long hairy inferior appendages. Legs entirely yellow. Middle tibiae with five dorsal, two external, three ventral, and four internal bristles. Wings with moderately dark brownish markings as follow: a spot on r-m and fM, the whole distal half of the membrane dark but more intensively anteriorly. Halteres with yellowish stem and dark knob.

Length of body and wing, 2½ mm.

Type: Waiho (Tonn.), 20th Jan., 1922, in Cawthron Inst. coll.

Paratype: idem 30th Jan., 1922.

13. Zygomyia rufithorax n. sp. Tonn.

♂ Head and appendages brown; base of antennae orange. Thorax yellowish-orange with exception of disc of scutellum, middle of postnotum and some parts of pleurae darker. Abdomen brown; hypopygium orange. Leg yellow entirely; middle tibiae with five dorsal, three external, three ventral, and three to four internal (one long) bristles. Wing with a central brownish spot on r-m and fM and a dark fascia covering completely distal two-fifths of the membrane which is darker anteriorly. Halteres orange.

♀ Similar to male, anal lamellae more or less orange.

Length of body 2, mm.; wing 2½ mm.

Type: Otira (Tonn.), 10th Feb., 1922, in Cawthron Inst. coll.

Allotype: Mt. Arthur, 21st Dec., 1922.

Paratypes: Mt. Arthur, 24th Dec., 1921; Otira, 10th Feb., 1922; Khandallah, 30th Nov., 1921; Nelson, 12th Dec., 1921; Waiho, 30th Nov., 1922 (Tonn.).

Specimens in Brit. Mus.: Ohakune (Harris); Leith Valley (Howes); Queenstown (Curtis).

14. Zygomyia longicauda n. sp. Tonn.

♂ Head and appendages brown, base of antennae orange; antennae rather long; flagellar segments twice as long as wide. Mesonotum dark orange, the rest of the thorax somewhat darker. Abdomen brown, also hypopygium which is provided with rather long lateral lamellae. Legs yellow, tip of hind-tibiae brown. Mid-tibiae with four dorsal, two external, no ventral, and three to four internal (all small) bristles. Wings as in rufithorax. Halteres orange.

Length of body and wing, 2½ mm.

Type: Maitai Valley (Tonn.) 7th Mar., 1922, in Cawthron Inst. coll.

15. Zygomyia crassicauda n. sp. Tonn.

♂ Head and appendages brown, base of antennae paler. Thorax brown, propleurae orange. Abdomen brown; hypopygium very large, about one-third of abdomen, much swollen and roundish, its colour dull brown, paler below where there is roundish shining space. Legs yellow; middle tibiae with five dorsal, three external, two to three ventral, and two internal bristles. Wings with a small central dark spot on r-m and fM and a dark apical fascia on the last two within the middle of which there is a small round clear spot in cell R₅ Halteres with yellow stem and black knob.

Length of body, 2 mm.; wing, 2½ mm.

Type: Otira, 10th Feb., 1922 (Tonn.), in Cawthron Inst. coll.

16. Zygomyia crassipyga n. sp. Tonn.

♂ Head and appendages brown, base of antennae slightly paler. Thorax brown, slightly ferrugineous on notum. Abdomen brown. Hypopygium very large, about two-fifth of abdomen, brown with yellowish clasper. Pubescence of body dark. Legs entirely yellow; middle tibiae with five dorsal, three external, three ventral, and one internal bristles. Wing with the central fascia extending from costa on to r-m and fM. Apical brown fascia darker anteriorly and with a small round subapical clear spot in cell R₅, the space between this spot and wing-tip not being as dark as the rest of the fascia. Veins R₅ and M₁ somewhat arcuate in front of the little subapical clear spot. Halteres yellow.

♀ Base of antennae and mesonotum someyhat paler. Tip of posterior coxae, base of posterior femora and hind knees slightly dark. Anal lamellae dark.

Length of body, 2 mm.; wing, 2½ mm.

Type: Waiho (Tonn.), 28th Jan., 1922, in Cawthron Inst. coll.

Allotype: Kaikoura, 23rd Feb., 1922.

Paratype: Otira, 10th Feb., 1922.

Specimen in Brit. Mus.: Ohakune (Harris).

17. Zygomyia guttata n. sp. Tonn.

♂ Head and appendages brown, antennae slightly paler at base, moderately long, the flagellar segments scarcely longer than wide. Thorax brown, sides of mesonotum slightly greyish. Abdomen brown; hypopygium very small. Legs yellow, posterior coxae and femora slightly and narrowly darkened at tip, extremity of posterior tibiae distinctly darkened; middle tibiae with five dorsal, three external, three ventral and one to two internal bristles. Wing with central dark fascia extending from costa on to r-m and stem of M but scarcely on fM; apical fascia on distal two-fifth of wing, conspicuously darker anteriorly and with a roundish clear spot in middle of cell R₅, this spot extending slightly and inconspicuously in cell M₃. Halteres yellowish-white.

Length of body, 1⅗ mm.; wing, 2 mm.

Type: Nelson (Tonn.), 4th Mar., 1922, in Cawthron Inst. coll.

18. Zygomyia varipes n. sp. Edw.

♂ Head blackish-grey, with black bristles and pale pubescence. Antennae black, scape hardly lighter; flagellar segments about half as long again as broad. Palpi brownish. Thorax blackish-brown, slightly dusted with grey, shoulders narrowly ochreous; bristles black, pubescence pale. Three strong pteropleural bristles. Abdo men blackish somewhat shining, anal lamellae small and dark. Legs ochreous; all coxae with distinct black marks on outer side at tip; front femora dark beneath; posterior femora with about the basal and apical thirds black; hind tibiae black at tip. Middle tibiae with four dorsal, three external, one ventral, and two internal bristles. Wings with the ground-colour clear; a well-marked dark band extending from costa, where it is broadest, through base of cell M₁ to Cu,

above which it again broadens towards base of wing; tip broadly dark, including a clear spot which just touches R₅ and M₃ and is slightly constricted at M₁. Halteres white.

Length of body or wing, 3 mm.

Type: Queenstown (L. Curtis), 25th Mar., 1923, in Brit. Mus. coll.

19. Zygomyia humeralis n. sp. Tonn. (Fig. 296.)

♂ Head brown; palpi yellow; antennae brown with orange scape. Thorax dull blackish-brown with anterior corners of mesonotum orange and its side greyish; its pubescence rather long, yellowish. Abdomen shining dark brown; hypopygium as in fig. 296. Legs yellow; tip of hind-femora broadly dark; mid-tibiae with four dorsal, three external, one ventral, and two internal bristles. Wing with a dark marking on r-m and fM; the whole of costal cell but its base darkish; distal half of wing dark with a clear spot in cells R₅ and M₃, this spot not touching vein R₅. Halteres with yellow stem and black knob.

♀ Similar to male; size somewhat larger. Anal lamellae orange.

Length of body and wing, 1¾ mm.

Type: Nelson (Tonn.), 13th Oct., 1923, in Cawthron Inst. coll.

Allotype: Kaikoura, 22nd Feb., 1922.

Paratypes: Cass, 27th Nov., 1924; Christchurch, 17th Dec., 1924; Nelson, 1st Sept., 1923; and 15th Dec., 1921.

The antennae are sometimes completely dark.

20. Zygomyia flavicoxa Marsh. (Figs. 90, 294.)

Marshal, Trans N.Z. Inst, 28, 1896, p. 297.

This species and the preceding one are scarcely distinguishable but by the structure of the male's hypopygium. Fig. 294 is made after the hypopygium of the type.

Besides Wanganui and Lincoln, this species is known from Ohakune (Harris); Governors Bay (Tapley); Christchurch (Campbell).

21. Zygomyia marginata n. sp. Tonn.

♂ Head brown; palpi dark orange; antennae brown with paler base, their length moderate, flagellar segments only a little longer than wide. Thorax brown, mesonotum somewhat paler with some cinereous reflections in certain positions. Abdomen brown; hypopygium with dorsal lamellae rounded on the outside and pointed at tip. Legs entirely yellow; mid-tibiae with five dorsal, three external, two ventral, and one internal bristles. Wing with a rather large central fascia on r-m and fM and extending against costa; apical fascia darker on anterior border and with a clear spot in middle across the cells R₅ and M₃. Halteres yellow.

♀ Similar to male; anal lamellae dark.

Length of body and wing, 2½ mm.

Type: Otira, 10th Feb., 1922 (Tonn.), in Cawthron Inst. coll.

Allotype: Nelson (Tonn), 27th June, 1922.

Paratypes: Otira, 10th Feb., 1922; Lake Brunner, 4th Feb., 1922; Nelson, 27th June, 1922.

Specimens in Brit. Mus.: Ohakune (Harris); Governors Bay (Tapley); Queenstown (Curtis).

22. Zygomyia acuta n. sp. Tonn. (Fig. 85.)

Very similar to Z. marginata from which it differs chiefly by the hypopygium, the superior lamellae being fusiform, acute at apex which carries a bristle. Mesonotum paler. Middle tibiae with five dorsal, three external, three ventral, and three internal (one long) bristles. The first half of cell M₃ is clear, the limit of apical dark fascia is therefore in that cell not on the same level as that of the cells above and below as it is the case in Z. marginata and the allied species. Female with dark anal lamellae.

Type: Waiho (Tonn.), 30th Jan., 1922, in Cawthron Inst. coll.

Allotype: idem.

23. Zygomyia albinotata n. sp. Tonn. (Fig. 92.)

♂ Head and its appendages brown; antennae slightly lighter at base; flagellar segments as an average not twice as long as wide. Thorax brown with a slight grey pruinosity; mesonotum with three darker stripes not distinct in all positions and more or less fused together. Legs yellow, tip of posterior coxae and base of posterior femora below dark; tip of hind-femora and tibiae darkened. Midtibiae with four dorsal, three external one to two ventral and three to four (one long) internal bristles. Wing with a rather large central dark fascia on r-m and fM and extending on costa; apical fascia darker anteriorly and with a clear space in middle of cells R₅ and M₃. Halteres yellow.

♀ Similar to male; anal lamellae dark orange.

Length of body and wing 2½ mm.

Type: Mt. Arthur (Tonn.) 22nd December, 1921. In Cawthron Inst. coll.

Allotype and paratypes: idem.

24. Zygomyia truncata n. sp. Tonn. (Fig. 304.)

Very closely related to Z. albinotata from which it differs mainly in the hypopygium, the superior lamellae of which is shown in Fig. 304. Middle tibiae with four dorsal, two external, two ventral, and two to three internal bristles.

Type: Mt. Arthur (Tonn.), 26th Dec., 1921, in Cawthron Inst. coll.

Allotype: Dun Mount., Nelson (Tonn.), 5th Feb, 1922.

25. Zygomyia unispinosa n. sp. Tonn. (Fig. 293.)

Very similar to Z. albinotata for size and colouration as well as for wing-pattern, but there is no distinct stripes on mesonotum. The middle tibiae carry only one ventral bristles. By the shape of the superior lamellae of the hypopygium it comes nearer to Z. marginata from which it differs, however, by the larger size, the colouration of the legs and by the larger subapical clear spot of the wing.

Length of wing and body, 3 mm.

Type: Mt. Arthur, 21st Dec., 1921 (Tonn.), in Cawthron Inst. coll.

Paratype: one male idem.

26. Zygomyia trifasciata n. sp. Tonn. (Fig. 94.)

♂ Head and appendages dark; antennae lighter at base, flagellar segments twice as long as wide. Thorax ferrugineous-brown. Abdomen brown, hind-border of segments slightly yellowish. Legs yellow; middle tibiae with four dorsal, three external, two ventral and two to four internal bristles. Wing with a central spot on r-m and fM and a dark tip; midway between these two dark fasciae there is a rather narrow transverse dark band from R₁ to M, the clear spaces on each side being wider than the dark band itself. Halteres with a darkish knob.

Length of body and wing, 2½ mm.

Type: Dun Mt., Nelson (Tonn.), 5th Jan., 1922, in Cawthron Inst. coll.

27. Zygomyia nigrita n. sp. Tonn. (Fig. 289.)

♂ Head and body completely dark; palpi and antennae brown, base of antennae slightly lighter; mesonotum dull with greyish reflection. Pubescence of body yellowish. Legs yellow, tip of all coxae base of posterior femora below and tip of hind-tibiae darkened. Midtibiae with four dorsal, three external, two ventral, and three internal bristles. Wing with a central spot on r-m and fM; a very slight shadow in anal field at level of fM; a transverse band between third fifth and second third of wing, darker anteriorly; last quarter of wing dark, this last fascia separated from preceding one by a transverse clear band which does not quite reach posterior border. Halteres yellow.

♀ Similar to male; anal lamellae dark orange.

Length of body and wing, 2½ mm.

Type: Tahunanui, Nelson (Tonn.), 21st July, 1922, in Cawthron Inst. coll.

Allotype: idem.

Paratypes: Nelson, 28th Sept., 1923 and 9th Oct., 1923.

28. Zygomyia eluta n. sp. Edw. (Figs. 95, 295.)

Head blackish, as are palpi and antennae, the latter only slightly brownish at base; flagellar segments about half as long as broad. Thorax uniformly blackish-grey; hair brownish; bristles black; three strong propleural and two pteropleural bristles. Abdomen blackish, with scanty pale hair; hind margins of segments narrowly pale; hypopygium small and hidden. Legs ochreous, tarsi and spurs dark; coxae unmarked; middle tibiae with three to four dorsal, two to three external, one ventral and two to three small internal bristles; bristles beneath first hind tarsal segment very little longer than the diameter of the segment. Wing mainly clear; a slight dark seam over r-m and stem of median fork; a narrow and faint brownish band from costa a short distance before tip of R₁, reaching at most as far as M₃, but often not reaching M₁; tip of wing slightly darkened. Venation normal; Sc short. Halteres yellow.

Length of body, 2½–3 mm.; wing, 2½–3 mm.

Type ♂: Governors Bay (J. F. Tapley), in Brit. Mus. coll.; and numerous paratypes ♂ ♀, Aug.-Sept., 1922; Queenstown (L. Curtis); 1 ♂ 2 ♀, 10th Sept., 1923; Ohakune (T. R. Harris); 1 ♂, Aug., 1922.