Hydrophorinae, Lioy, 1864

Bickel, Daniel J. & Kerr, Douglas Steven, 2018, Scorpiurus aramoana (Diptera: Dolichopodidae), a new species from New Zealand, Zootaxa 4422 (1), pp. 78-84 : 79

Key to the New Zealand genera of Hydrophorinae and species of Scorpiurus

[modified after Bickel (1991) & Masunaga (2017)]

1 Pair of large postvertical setae usually present on dorsal postcranium, not in line with postorbital series; abdomen usually dorsoventrally flattened; postorbital setae strong dorsally, but forming field of pale setae across ventral postcranium; male face usually wide; fronto-clypeal suture distinct, at least laterally; clypeus usually produced anteriorly; palpi usually large in both sexes, and covered with short setae; eyes pubescent [other characters: vertex not strongly excavated laterad of ocellar tubercle; vein M 2 absent; scape dorsally bare; posterior mesonotum not strongly flattened; dorsal postcranium flat or slightly convex]; HYDROPHORINAE .................................................................................. 2

- Features various, but in particular: postvertical setae, if present, near vertex, and usually small; abdomen usually ovate and rarely dorsoventrally flattened; postorbital setae various; male face often narrow with fronto-clypeal suture obscured [other characters various].................................................................... other Dolichopodidae

2 Vertical seta positioned along orbit halfway between vertex and level of antenna; arista apical..................................... Abatetia Miller [ A. robusta (Parent) , also several undescribed species; small (~ 3.0 mm) species, marine littoral]

- Vertical seta positioned near to crown of vertex; antenna various................................................ 3

3 Acrostichal setae uniseriate, even if short................................................................... 4

- Acrostichal setae biseriate, even if short or of irregular occurrence, or totally absent................................. 5

4 Coxa III bare of major setae; arista short, not much longer than antenna, and male arista simple; male tarsus I unmodified; postpedicel with ventral incision; legs black with dense grey pruinosity; femur I swollen at base, usually with strong black ventral setae...................................................................................................... Hydrophorus Fallén [ H. praecox (Lehmann) , widespread Old World species; marine and lacustrine littoral habitats]

- Coxa III with distinct lateral seta; arista more than four times longer than antenna, and male arista with small black apical flag; all tarsomeres on male leg I flattened and subtriangular with basitarsus I greatly enlarged, and all mostly covered with silvery pruinosity; postpedicel entire; femora and tibiae mostly yellow; femur I unmodified.......................................................................... Helichochaetus discifer Parent [monotypic genus; forested riverine habitats]

5 Acrostichal setae short and irregularly biseriate ( NZ species) or totally absent; hypopygium usually subrectangular, elongate; notopleuron with single seta; arista dorsal on postpedicel; palpi often very large and triangular.......................................................... Thinophilus Wahlberg [single described NZ species, T. milleri Parent ; marine littoral]

- Acrostichal setae distinctly biseriate ( Fig 1a ); hypopygium large and subspherical with elongate bladelike cerci (as in Figs 1f, g ); notopleuron with two setae; arista apical on postpedicel; palpi short and ovate (as in Figs 1h, i )............................................................................... Scorpiurus Parent [endemic NZ genus; marine littoral]................................................................................................... 6

6 Lower face and palpi with golden pruinosity ( Figs 1h, i ); males with tarsomeres on legs I & II distinctly flattened and covered with orientated silvery pruinosity ( Figs 1c, d, e ); femora with mostly whitish setae (South Island)................................................................................................... Scorpiurus aramoana sp. nov.

- Lower face and palpi with grey pruinosity; males tarsomeres I & II unmodified, not flattened; femora with mostly black setae .................................................................................................... 7

7 Acrostichal setae continuing onto flat part of scutum in front of scutellum; proepisternum with 8–11 long white setae each on upper and lower parts; femora mostly dark metallic green with dense grey pruinosity, and only apical fifth yellowish; male femur II with two groups of short white ventral setae, near base of and at mid-length (North Island, northern South Island)....................................................................................... S. aenescens Parent

- Acrostichal setae positioned anterior to prescutellar depression; proepisternum with 5–8 long, white setae each on upper and lower parts; femora dark metallic green basally with distal half yellowish; male femur II bare of ventral setae (North Island, northern South Island).................................................................. S. thorpei Masunaga

Figures

FIGURE 1. Scorpiurus aramoana sp. nov.: a. male head and thorax, dorsal view; b. male wing, dorsal view; c. male habitus, ventral view; d. male anterior habitus, right ventral view; e. male left tarsus I, dorsal view; f. cleared male postabdomen (left surstylus removed), left lateral view; g. male postabdomen, left lateral view; h. male head, anterior; i. male head and thorax, right anterior view. Scale bar in mm.