New species of the genus Cyamops Melander from New Zealand (Diptera, Periscelididae, Stenomicrinae)

Abstract Two new species of the genus Cyamops (Diptera: Periscelididae), the first from New Zealand, are described. The two newly described species are: Cyamops alessandrae and Cyamops crosbyi. A key to the genera of the subfamily Stenomicrinae and to the species of Cyamops from the Australasian/Oceanian Region and detailed illustrations of structures of the male terminalia are provided.


Introduction
The genus Cyamops Melander 1913 includes 30 valid species: two from the Afrotropical Region; 12 from the Australasian/Oceanian Region; three from the Nearctic Region, seven from the Neotropical Region, five from the Oriental Region, and one from the Palearctic Region (Mathis and Rung 2011). Previously none was known from New Zealand. The purpose of this paper is to describe two new species from New Zealand that were recently discovered. These discoveries were made while conducting general research on acalypterates of this island nation.
To facilitate identification of these species, we have included a key to the genera of the subfamily Stenomicrinae and to the species of Cyamops from the Australasian/ Oceanian Region (modified from the key produced by Baptista and Mathis 2000). We have also produced detailed illustrations of structures of the male terminalia of the new species.

Methods and materials
The descriptive terminology, with the exceptions noted in Mathis (1994, 2000), is that published in the Manual of Nearctic Diptera (McAlpine 1981). The format for the species' description adheres to Mathis (1994, 2000). Because specimens are small, less than 3.00 mm in length, study and illustration of the male terminalia requires use of a compound microscope. For most of the structures of the male terminalia, we follow the terminology adopted by other workers in Periscelididae (Baptista and Mathis 1994, 2000, Sueyoshi and Mathis 2004. The species' descriptions are composite and not based solely on holotypes. Three venational ratios used in the descriptions of new species are based on the largest, smallest, and one other specimen and is defined as: (1) Wing ratio: straight line distance between wing base and apex/greatest straight line distance from anterior margin to posterior margin. (2) 1st costal ratio: the straight line distance between the apices of R 1 and R 2+3 (costal section II)/distance between the apices of R 2+3 and R 4+5 (costal section III). (3) 2nd costal ratio: straight line distance between the apices of R 2+3 and R 4+5 (costal section IV)/distance between the apices of R 4+5 and M (costal section III).
Most specimens examined as part of this study are deposited in the New Zealand Arthropod Collection (NZAC, Auckland, New Zealand). A few specimens have been deposited in the Smithsonian Institution (USNM) and California Department of Food and Agriculture (CDFA).
Dissections of male and female genitalia and descriptions were performed using the method of Clausen and Cook (1971) and Grimaldi (1987). Microforceps were used to remove abdomens, which were macerated in a hot sodium hydroxide solution. Cleared terminalia were rinsed in distilled water and 70% ethanol and then transferred to glycerin for observation. For long-term storage, abdomens were placed in an attached plastic microvial filled with glycerin and attached to the pin supporting the remainder of the insect from which it was removed.
Head: Typically dark brown in ground color; fronto-orbits below the insertion of fronto-orbital setae, parafacial and genal region usually with silvery white microtomentum; occipital region shiny, sparsely microtomentose; lower face usually strongly microtomentose below genal region; median plate of clypeus shiny brown; head usually broader than thorax; postcranium strongly concave; eye bearing interfacetal setulae, shape of eye in profile more or less diagonal, lower anterior facets enlarged and encroaching on facial region more in males than in females (males and females of two species from Oceanic Region have the face with almost the same width); eyes closer together at lower edge of frons than at top of head; frons slightly longer than wide; ocel-lar tubercle small, situated near vertex; mesofrons somewhat depressed, concave; antennal form as for other Periscelididae; arista 3-segmented (see D.K. McAlpine 1983), branched, in some species with basal bifurcate rays; face in profile nearly straight to distinctly angulate, ventral portion (below narrowest gap between eyes) more broadly developed, sometimes shallowly carinate medially, carina narrow to broad, but always broader in females; lower epistomal margin of midface extended around oral opening to form a narrow peristomal area; clypeus a large inverted U, somewhat retracted in males but easily visible in females; palpus short, compressed, with silver luster when viewed under certain angles. Chaetotaxy: Lateral vertical seta slightly to strongly divergent, curved outward; medial vertical and postocellar setae lacking; 2 pairs of frontoorbital setae, inner pair reclinate, sometimes oriented outward, outer pair proclinate, in most cases pointed inward; inner fronto-orbital seta usually about 3/4 length of outer, rarely shorter; fronto-orbits typically bearing small setulae below setae; true vibrissa apparently absent, but uppermost pair of facial setae developed as porrect, anaclinate "pseudovibrissae," followed by a row of peristomal setulae and setae at margin of gena; pseudovibrissae sometimes placed externally to row of peristomal setae.
Thorax: Shiny, brown to dark brown, sparsely whitish microtomentose, microtomentum more dense at lower portion of katepisternum; calypter brown; postscutellum developed; greater ampulla convex; prosternum bare. Chaetotaxy: Acrostichal setulae in 2 more or less regular rows, slightly diverging behind, being strongly reduced in some species; dorsocentral setae 0+1 or 0+2, 1st seta, when present smaller, 1 row of dorsocentral setulae in front of setae; some setulae also present between acrostichal and dorsocentral rows in some species; supra-alar seta 1, preceded by small setulae, which can be sometimes strongly reduced; scutellum typically with 1 or 2 pairs of setae, basal pair, when present, smaller, notopleural setae 1+1, 1st seta usually longer; katepisternal seta 1, located dorsally (sometimes a 2nd, smaller and weaker seta is present); anepisternum bare or with 1 seta and few setulae along posterior margin. Wing: Costal vein without true costal breaks, but with a weakness before end of vein R 1 ; costal vein extended to vein M; crossvein bm-cu either present, delimiting discal cell from cell bm (species in Afrotropical, Australian, Nearctic, Neotropical, Oriental, and Palearctic Regions), or absent (some Oceanian species); anal vein sometimes strongly reduced in length; anal cell present, well delimited. Legs: Posteroventral setulae of forefemur sometimes differentiated as a row of distal small, spine-like setulae; mid tibia bearing an apicoventral spine.
Discussion. The Australasian/Oceanian fauna demonstrates variation in characters that are constant in American and Afrotropical species, i.e., sexual dimorphism in the shape of the face (absent in C. micronesicus and an undescribed species from Ponape) and presence of crossvein bm-cu. All species, however, have a single pair of dorsocentral setae, and the anepisternum lacks setae along the posterior margin. Description. Adult body length 1.90-2.60 mm; wing length 2.10-3.00 mm; wing width 0.70-1.10 mm. Head: Ocellar tubercle polished; shiny spot on vertex large and distinct, extended from ocellus 2/3 distance to eye margin; depressed region of frons deep, velvet. Pedicel brownish on dorsal half, otherwise yellow; basal aristal rays minutely bifurcate apically; basal flagellomere yellow, infuscate dorsally. Face constricted medially by the anteroventral margin of the eyes, expanded into a ventral triangular region below level of pseudovibrissae and bearing a vertical, midfacial, yellow carina, facial triangle microtomentose, yellow to whitish yellow, bordered dorsolaterally with yellow stripe, facial setulae in yellow stripe, some specimens with blackish yellow on ventrolateral margin; gena when viewed anteriorly conspicuously silvery white microtomentose, in lateral view more yellowish tan; labellum and palpus pale yellow; face produced, very shallowly angulate. Chaetotaxy: Inner fronto-orbital setae slightly divergent, slightly  Fig. 1. All setae on the epandrium are abbreviated in Fig. 2 and 3. Abbreviations: ep, epandrium; s, surstylus; 6-7S: 6th and 7th abdominal sternites. Scale bar: 1 = 0.20 mm, 2-4 = 0.12 mm. smaller than lateral vertical seta; arista bearing 6-7 dorsal, 3 ventral rays; pseudovibrissae oriented dorsally; peristomal setae 6-7.
Etymology. The species epithet, crosbyi, is a genitive Latin patronym to honor and recognize the numerous contributions of Dr. Trevor K. Crosby to the study of Diptera from New Zealand, the family Simuliidae in particular.