Chersodromia stenopsis Maeda, 2011, sp. nov.
Creators: name: Maeda, Takuya
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Hybotidae
Chersodromia
Chersodromia stenopsis

description: Chersodromia stenopsis sp. nov.
(Figs. 10, 17, 50–56)
Diagnosis. A small, greyish species measuring less than 1.5 mm. Face extremely narrow. Katepisternum dull. Wings normally developed. Male terminalia: right surstylus being pointed lobe; left surstylus with bifurcate outermost lobe; left cercus small. Setae on head and thorax dark brown, small (postalar setae conspicuously small); setulae on head and thorax whitish, small. Vertical setae (2 pairs) present; proepisternal setae/setulae, posthumeral setae and supra-alar setae absent.
Description. Male (Fig. 10). Body length 1.19–1.34 mm; head width 0.32–0.35 mm; wing length 1.45–1.60 mm. Head (Fig. 50) grey in ground-colour and whitish pollinose; palpus whitish pollinose; proboscis pale brown, slightly shining; antenna brown; all setae on head dark brown; all setulae on head whitish with brown tinge. Frons moderate in width; in frontal view face extremely narrow, narrower than median ocellus. Ocellar setae (2 pairs) and vertical setae (2 pairs) short, as long as scape and pedicel combined. In frontal view gena narrow, 1/7 as wide as maximum eye height. Occiput with setulae. Antenna (Fig. 51): postpedicel round in lateral view, bearing setulae along anterior margin; extension of postpedicel present dorsoapically; stylus moderate in length, ca. 2 times as long as pedicel and postpedicel combined. Palpus with some setulae and sensory pit, but it hardly visible without preparation on slide.
Thorax (Fig. 52) grey in ground-colour and whitish pollinose; no polished area on katepisternum; all setae brown; all setulae whitish with brown tinge. Vestiture on thorax: proepisternal seta/setula absent; 1 pair of long postpronotal setae; no posthumeral setae; 2 pairs of notopleural setae; no supra-alar setae (1 or 2 pairs of supra-alar setulae present); 1 pair of small postalar setae; some dorsocentral setulae in multiple rows; 1 pair of incomplete rows of some acrostichal setulae; 1 pair of long apically scutellar setae; 1 pair of tiny subapical scutellar setulae.
Wing (Fig. 17) normally developed, clear with grey tinge; veins pale brown. Basicosta with 1 dark brown seta; costa with pale brown setulae along anterior margin, ending at connection with vein M1+2; subcosta absent; R1 meeting costa before midway of wing; radial sector moderate in length; CuA1 indistinctly connected to wing margin; anal vein reduced to pale, fold-like line. Calypter minute, whitish with brown tinge. Halter pale brown, large.
Legs pale brown, somewhat slender. Setae on legs brown/pale brown; all setulae on legs whitish with brown tinge. Fore femur sparsely covered with setulae (setulae of anteroventral and posteroventral rows long), with 1 short anterior preapical seta and 1 posterior preapical seta. Fore tibia covered with setulae, with 1 anteroventral preapical seta and 1 posteroventral preapical seta. Fore tibial gland indistinct. Mid femur covered with setulae, with 1 anterior preapical seta, 1 anteroventral preapical seta, 1 posterior prearical seta and 1 posteroventral preapical seta. Mid tibia slightly inflexed, covered with setulae, with anteroventral row of 13–16 short, brown spinulae (apical one longest), 1 anterior preapical seta, 1 posterior preapical seta, 1 posteroventral preapical seta and 2 anterodorsal setae. Hind femur covered with setulae (setulae of posteroventral row relatively long), with 1 anteroventral preapical seta. Hind tibia covered with setulae, with 2 dorsal setae, 1 anterodorsal preapical seta, 1 anterodorsal seta, 1 anterior preapical seta, 2 anterior setae and 2 anteroventral setae. Fore, mid and hind tarsomeres covered with setulae.
Preabdomen sparsely covered with whitish setulae; tergites and sternites brown in ground-colour and sparsely whitish pollinose; membrane pale brown in ground-colour and sparsely whitish pollinose. Tergites 1–7 each with 1 or 2 brown plaques laterally and 1 pair of small pits dorsolaterally. Eighth segment hidden.
Terminalia (Figs. 53–56). Coloration: right surstylus generally brown, partially shiny black; right epandrial lamella brown in ground-colour and sparsely whitish pollinose; cerci brown; left surstylus, left epandrial lamella and hypandrium shiny dark brown. Right surstylus being pointed lobe (Figs. 53, 55), boundary line between it and right epandrial lamella obscure. Right epandrial lamella with brown setulae (Fig. 53), with small setulae in dorsoapical part, which somewhat flattened (Fig. 55). Left surstylus composed of several lobes; outermost lobe large, bifurcate (Fig. 54). Right and left cerci weakly sclerotized, small (lengths of right and left cerci almost same), apically with some setulae (Fig. 56).
Female. Body length 1.37–1.39 mm; head width 0.34–0.35 mm; wing length 1.54–1.65 mm. Closely resembling males except in structure of mid tibia and terminalia. Mid tibia not inflexed, without anteroventral row of spinulae. Cercus brown.
Type material. HOLOTYPE 3, labelled: Russian Far East, S. Primorye, Gamov Pen., Vityaz’ Bay, 24.viii.2010, leg. T. Maeda (IBSS). Paratypes: 10 3, 13 Ƥ (dried specimens), same data as holotype; 10 3, 9 Ƥ, same loc., 23.viii.2010. Other specimens examined (in alc.): 35 3, 60 Ƥ, Amur Bay, 3–5 km E. Tavrichanka, 22.viii.2010; 2 Ƥ, Zarubino, 25.viii.2010; 4 3, 4 Ƥ, Gamov Pen., Astaf’ev Bay (scrub zone), 26.viii.2010; 30 3, 34 Ƥ, Gamov Pen., Telyakovskiy Bay, 24.viii.2010; 5 3, 2 Ƥ, Pos’et, 25.viii.2010; 17 3, 20 Ƥ, Nazimov Cape, 28.viii.2010.
Type depository. Some paratypes are in FMNH, IBSS, NIAES, USNM, OUMNH and TMC.
Etymology. The specific epithet “ stenopsis ” is Latin meaning “narrow face”.
Distribution. Russian Far East: southern part of Primorsk Territory.
Remarks. This species was found on different kinds of seashores, but appears generally to prefer habitats in the upper littoral zone on shores with abundant washed up debris, comprising mainly seaweeds. However, on the shore of Astaf’ev Bay (Fig. 3) it was very rare and only found in the scrub zone probably because C. nubifera occupied washed up debris.
It is very easy to distinguish C. stenopsis from the other species in the Russian Far East by its very narrow face.
description: Published as part of Maeda, Takuya, 2011, New species of Chersodromia from the Russian Far East (Diptera: Empidoidea: Hybotidae: Tachydromiinae), pp. 1-24 in Zootaxa 2979 on pages 17-20, DOI: 10.5281/zenodo.202911