Nostima duoseta Cresson

Edmiston, James F. & Mathis, Wayne N., 2007, New Zealand species of the shore-fly genus Nostima Coquillett (Diptera: Ephydridae), Zootaxa 1661, pp. 1-16 : 5-8

Nostima duoseta Cresson

( Figs. 1–6 , 15 , 18 )

Nostima duoseta Cresson 1943: 3 .- Mathis 1989: 647 [Australasian/Oceanian catalog].- Mathis & Zatwarnicki 1995: 191 [world catalog].

Diagnosis. This species is distinguished from congeners by the following combination of characters: wing with numerous brown spots as follows: crossveins r-m and dm-cu brown surrounded with dark spots; dark spots variable: 4 or 5 across r1 cell, 3 or 4 across r2+3 cell, 6 or 7 in r4+5 cell, 3 distally to dm-cu, 4 or 5 small circular spots in cua1; thorax with dense silvery gray microtomentum on postpronotum; tergites 2 through 5 with microtomentose spots.

Description. Adults. Small shore flies, body length 1.10–1.42 mm; yellowish brown to brown with silvery white and yellowish silver microtomentum.

Head. Frons brown with yellowish silver microtomentum, anterior semicircular margin brown with yellowish silver microtomentum. Occiput brown with yellowish silver microtomentum medially, silvery gray microtomentum laterally. Lateral vertical seta ½ to 2/3 length of medial vertical seta; paravertical seta absent. Scape brown; basal flagellomere with dorsal 1/2 brown and ventral 2/3 yellowish brown; arista with minute dorsal branches. Facial background brown with yellowish silver microtomentum, microtomentum less dense laterally; band of silvery gray microtomentum along eye margin from antennal bases, along parafacial, and extending to the gena. Gena covered with silvery gray microtomentum; postgena with sparse silvery gray microtomentum. Maxillary palpus brown; prementum yellowish brown.

Thorax. ( Fig. 15 ). Scutal length 0.34–0.46 mm; scutellar length 0.16–0.23. Mesonotum yellowish-brown with yellowish silver microtomentum; silvery gray microtomentose vitta anteromedially extending posteriorly to form v-shaped vitta with point posterior of anterior dorsocentral seta; silvery gray microtomentum along dorsocentral line, and lateral to dorsocentral line, most dense anteriorly extending to postpronotum, laterally at base of anterior dorsocentral setae, and posteriorly in postalar region; scutellum yellowish brown with yellowish silver microtomentum slightly darker mediolaterally, laterally with silvery gray microtomentum contiguous with silvery gray lateral vitta of mesonotum; anepisternum brown with silvery gray microtomentum; katepisternum brown with silvery gray microtomentum; anatergite brown with yellowish silver microtomentum. Chaetotaxy: anterior dorsocentral seta 2/3–3/4 length of posterior seta; anterior notopleural seta 3/4 length of posterior seta; lateral scutellar seta 2/3 length of apical seta. Wing ( Fig. 18 ): length 0.93–1.22 mm; width 0.41–0.60 mm; costa-vein ratio 0.41–0.55; M-vein ration 0.24–0.31; background amber, maculate with brown spots, veins brown to dark brown; crosveins r-m and dm-cu brown surrounded with dark spots; dark spots variable: 4 or 5 across r1 cell, 3 or 4 across r2+3 cell, 6 or 7 in r4+5 cell, 3 distally to dm-cu, 4 or 5 small circular spots in cua1. Halter yellowish white. Legs dark yellowish brown; metathoracic tibia banded; tarsomere 5 yellowish brown and slightly darker than other tarsomeres.

Abdomen. ( Figs. 1–2 ). Background brown with yellowish silver microtomentum; tergite 3 with silvery gray microtomentum mediolateral spot and posteromedial silvery gray microtomentose spot with diffuse margins; tergite 4 and 5 with silvery gray microtomentum laterally along margin and posteromedial silvery gray microtomentose spots with diffuse margins.

Male terminalia. ( Fig. 3–5 ). Epandrium-surstyli fused; epandrium a narrow U-shaped band; cercus crescent-shaped and bearing several long setae; surstylus fused dorsally with epandrium, with long posteroventral setae on a broadly rounded posterior projection, medioventral projection triangular, anterior projections pointed and width somewhat variable; phallapodeme triangular in lateral view, posterior projection spatulate, anterior projection rounded with minute spike-shaped projections; aedeagus heavily sclerotized with anterior oval-shaped opening, rounded anterodorsal projection and rounded anteroventral projection; gonite and hypandrium broadly fused, with pointed posteroventral projection, prominent ventromedial setula, and rounded elongate dorsal projection; hypandrium rounded anteriorly.

Type specimen. The holotype female is labeled “ Australia Biró 1900/N[ew]. S[outh]. Wales [:] Mt. Victoria/733/ Nostima duoseta Cres. TYPE 6659 [red; species name and number handwritten].” The holotype is double mounted (minuten in a thin rectangular block of foam), is in excellent condition (left side of mesonotum caved in where minuten is inserted), and is deposited in the ANSP (6659).

SOUTH ISLAND. CO: Kawarau Gorge, Roaring Meg, Upper Powerhouse (44°52.8'S, 169°06.3'E), 14- 17 Nov 1977, J. C. Watt (1ɗ; NZAC); Old Man Range (15 km S Alexandra; 45°22'S, 169°13'E; 1695 m), 15 Feb 1976, L. L. Deitz (1ɗ; NZAC); Rock and Pillar Range (45°23'S, 170°17'E; 1220-1430 m), 11 Nov 1969, J. S. Dugdale (1ɗ, 2Ψ; NZAC). DN: Clyde (5 km E; 46°21'S, 169°50.7'E; Clutha River bank), 6 Dec 1977, E. I. Schlinger (1ɗ; NZAC). FD: Monowai (45°46.5'S, 167°37'E; 120 m), 20 Jan 2004, W. N. Mathis (1ɗ; USNM). MC: Christchurch (Styx Mill Reserve; 43°28.1'S, 172°36.4'E), 17 Oct 2002, D. and W. N. Mathis (1ɗ; USNM); Goldney Saddle (43°09.4'S, 171°44.7'E; 670 m), 15 Dec 1962, E. G. White (1; LUNZ); Ribbonwood (43°13.9'S, 172°35.9'E; fan above road; 670 m), 17 Jan 1962, E. G. White (2ɗ; LUNZ); Starvation Gully (43°41.6'S, 171°54.8'E; 915 m), 30 Nov-6 Dec 1961, E. G. White (1ɗ, 1Ψ; LUNZ). OL: Crown Peak (44°57'S, 168°55'E; 1200 m), 24 Jan 1981, S. S. Noyes, E. W. Valentine (1Ψ; NZAC). SL: Lumsden (45°44'S, 168°27'E), 2 Jan 1977, T. K. Crosby (1ɗ; NZAC).

Distribution. ( Fig. 6 ). Australasian/Oceanian: Australia (Australian Capital Territory, New South Wales, Tasmania, Western Australia), New Zealand (CO, DN, FD, MC, OL, SL, TO, WI).

Etymology. The epithet was probably derived from Cresson's distinction of this species with two pairs of dorsocentral setae from closely related Philygria that have three pairs of dorsocentral setae.

Remarks. The specimens from New Zealand all appear to have less well-developed wing spots than the Australian specimens. The same variability, however, has been seen to occur in series of specimens collected from a single locality in Australia. Nostima duoseta is a highly variable species both in external and internal characteristics. For example, similar to the variations in the wing maculation pattern, the anterior surstylar projection varies in width among specimens even when collected at the same locale.

Figures

FIGURE 6. Distribution map for Nostima duoseta Cresson.

FIGURES 1 – 5. Nostima duoseta Cresson (male). 1. Abdominal tergites, microtomentose patterns, dorsal view (scale bar = 0.25 mm). 2. Same, lateral view (scale bar = 0.25 mm). 3. Male terminalia (epandrium, cercus, fused surstylus), lateral view (scale bar = 0.1 mm). 4. Internal male terminalia, ventral view (scale bar = 0.1 mm). 5. Same, lateral view (scale bar = 0.1 mm).

FIGURES 15 – 17. Dorsal view of microtomentose patterns on mesonotum: 15. Nostima duoseta Cresson (male). 16. N. kiwistriata sp. nov. (female). 17. N. negramaculata sp. nov. (male). Scale bar = 0.25 mm.

FIGURES 18 – 21. Right wing, dorsal view: 18. Nostima duoseta Cresson (male). 19. N. kiwistriata sp. nov. (female). 20. N. negramaculata sp. nov. (male). 21. N. negramaculata sp. nov. (male). Scale bar = 0.5 mm.