Nostima Coquillett

Edmiston, James F. & Mathis, Wayne N., 2007, New Zealand species of the shore-fly genus Nostima Coquillett (Diptera: Ephydridae), Zootaxa 1661, pp. 1-16 : 3-5

Nostima Coquillett

Nostima Coquillett 1900:35 [type species: Nostima slossonae , by original designation].- Cresson 1930:101 [ Nostima compared with Philygriola ]; 1931:89 [key to genera]; 1941:1–2 [compared with Hydrina and key to species]; 1947:39–42 [key to subgenera and species]; 1948:3 [list].- Mathis 1989: 647 [Australasian/Oceanian catalog].- Foote 1995:425 [biology].- Hollmann-Schirrmacher 1998:44 [synonymy of Nostima with Philygria ].

Philygriola Hendel 1917:42 [type species: Notiphila picta Fallén 1813:254 , by original designation]; 1930:141 [compared with Hydrellia ]; Cresson 1930:101 [synonymy]; 1944:176–177 [subgeneric status]; Frey 1936:114 [Canary Islands].

Diagnosis. The genus Nostima can be distinguished from other genera of Hyadinini by the following combination of characters: face, thorax, and abdomen with distinct microtomentose patterns; fronto-orbital setae reduced; both medial and lateral vertical setae usually present; arista with very short to long branching rays; face distinctly carinate; eyes sparsely setulose; facial setulae of one row with setae (5–6), dorsomedioclinate, dorsalmost seta longest (homologous with vibrissal setae), ventrally each setulae slightly shorter than setula immediately dorsad in row, dorsalmost setula dorsomedioclinate, ventral setulae ventromedioclinate; dorsocentral setae 2, anterior seta postsutural (0+2); acrostichal setae lacking; 2 notopleural setae, anterior seta 3/4 length of posterior seta, posterior seta inserted dorsad of anterior seta; anterior scutellar setae shorter than apical setae; structures of male genitalia usually forming 2 fused complexes: (1) epandrium, cerci, and surstyli; (2) gonites and hypandrium; aedeagus lacking a sclerotized, basal collar.

Description. Adults, minute to very small flies, body length 0.91–1.42 mm.

Head. Mesofrons and vertex often with circular microtomentose area around ocelli; anterolateral frons with microtomentose triangle, usually darker in coloration than ocellar circle; fronto-orbital plate dark colored, bare or with dense pale microtomentum; frons bare or with sparse to dense microtomentum. Face generally paler than frons, yellow to dark yellowish brown with golden, yellowish silver, or silvery gray microtomentum extending to gena; medially along parafacial, a band with sparse or no microtomentum extending lateroventrally below gena. Gena concolorous with ventral parafacial plate, sometimes ventral gena bare or with sparse microtomentum; postgena and occiput concolorous with gena, sometimes with sparse microtomentum, sometimes shiny stripes with sparse microtomentum across postgena and occiput, contiguous with lateral thoracic stripe pattern. Chaetotaxy as follows: ocellar seta well developed, divergent, proclinate; postocellar seta minute, divergent, proclinate; orbital setae minute, 3–5 pairs, proclinate; medial vertical seta, prominent, mesoclinate; lateral vertical seta prominent, smaller than medial vertical seta, lateroclinate, rarely absent; medial vertical setae 1/2 to 3/4 length of lateral vertical setae; paravertical seta, if present, minute; postocular setae minute, in row along dorsolateral eye margin; facial setae minute, in a single row on shiny strip along parafacial plate; dorsalmost facial seta longest with other setae decreasing in length ventrally; genal setae minute, numerous, posterior. Antenna yellow, yellowish brown, or brown; scape, pedicel, and flagellomere 1 often darker in color dorsally; scape with row of setulae along distal ventral margin; basal flagellomere microtomentose with numerous setulae; arista filamentose or pectinate, dorsally branched. Maxillary palpus prominent, yellow to dark yellowish brown; prementum yellow to dark yellowish brown; mouthparts often withdrawn in preserved specimens.

Thorax. Mesonotum bare or with sparse to dense microtomentum, often marked with distinct vittae, background pale brown to dark brown, microtomentum golden, silver, velvety black or brown. Scutal length 0.34– 0.50 mm; scutellar length 0.16–0.23 mm; scutellum trapezoidal with posterior margin slightly rounded, dorsally concolorous with posterior margin of mesonotum, lateral margin sometimes with dense, silvery gray microtomentum contiguous with mesonotal vittae; pleura often paler than mesonotum, with striped pattern of silvery gray microtomentum contiguous with microtomentum pattern of gena and occiput; anepisternum bare or with sparse to dense microtomentum, often striped; katepisternum bare or with sparse to dense microtomentum; subscutellum brown to dark brown, bare or covered with sparse to dense microtomentum; anatergite brown to dark brown, bare or covered with sparse to dense microtomentum. Chaetotaxy as follows: acrostichal setae lacking; 2 postsutural dorsocentral setae, anterior seta 2/3 to 3/4 length of posterior seta; 3–5 presutural dorsocentral setulae; 1 prominent supra-alar seta; intra-alar setae minute; 2 notopleural setae, anterior seta 3/4 length of posterior seta, posterior seta inserted dorsad of anterior seta; 1 anepisternal seta, small to minute, inserted along posteromedial margin; 1 katepisternal seta, small to minute, inserted along dorsomedial margin; 1 scutellar setae inserted laterally, and 1 inserted posteroapically, lateral seta 1/3 to 3/4 length of posteroapical seta, lateral seta rarely absent. Wing length 0.93–1.46 mm; width 0.14–0.63 mm; costal vein ratio 0.24–0.82; M vein ratio 0.19–0.31. Legs yellow, yellowish brown, to dark brown; covered with rows of minute setulae; femora and tibiae often with patterned pale and dark areas; tarsomeres 4 and/or 5 often darker than proximal tarsomeres. Halter knob white, yellow, or yellowish brown.

Abdomen. Five abdominal tergites normally exposed in males, cercus well developed; 6–8 abdominal tergites normally exposed in females, cercus well developed; abdominal background color yellowish brown, brown, to dark brown; partially bare, and usually with distinct areas of sparse to dense microtomentum; tergites setulose, with setal rows along margins. Male genitalia: Abdominal tergite 5 dorsal to aedeagus and associated, internal structures. Male genitalia generally have: epandrium-cerci-surstyli complex with components separate or often variously fused; cerci usually densely setulose; ventral margin of surstylus sometimes with distinctive setal patterns; aedeagus simple, lacking a basal collar; aedeagus associated with a phallapodeme; gonite-hypandrium separate or often variously fused; lateroventral margin of gonite with a distinct seta projected posteroventrally; in some species of Nostima (though in none so far observed from New Zealand) a sclerite occurs dorsad of the aedegus and ventrad of the cerci, this structure has somtimes been called a 10th sternite, though this is unlikely, and the exact origin and homology of this structure is unknown.

Distribution. Although species of Nostima occur in all zoogeographical regions, there is greater species diversity in the tropics and subtropics.

Remarks. For most of the 20th Century, Nostima and its included species have been considered as a separate genus closely related to Philygria ( Zatwarnicki 1992, Mathis & Zatwarnicki 1995). More recently, Hollmann-Schirrmacher (1998) treated the genus Nostima as a junior synonym of Philygria . Edmiston & Mathis (2005), however, developed a broader view of character development within Hyadinini, and proposed the monophyly of Nostima based upon analysis of 38 New World Nostima species and observations of an African species ( Nostima flavitarsis Canzoneri & Meneghini ), an Australian species ( Nostima duoseta Cresson ), Philygria , and Garifuna . Three general tendencies are evident in characters and character states of Nostima , especially compared with other genera in the tribe Hyadinini. These tendencies are: (1) a reduction in body size; (2) a reduction in the number of setulae and setae; and (3) the fusion of genitalic structures. Reduction of the facial setulae into one row, and the reduction of dorsocentral setae are synapomorphies useful in distinguishing Nostima from the most closely related species within the genera Philygria and Garifuna . A branched arista is not a useful character for distinguishing Nostima of New Zealand and other parts of the Australasian Region from Philygria . Also, close examination of Afrotropical Philygria , such as Philygria mackieae (Cresson) , indicates that the aristal branches, while very reduced, are still observable. It is now evident that a reduced arista can be confusing and is not a universal synapomorphy.