Nothybus absens Lonsdale & Marshall 2016
Creators: name: Zhou, Jiale
name: Marshall, Stephen A.
name: Yang, Ding
Publisher: name: Zenodo
Year: 2021
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Nothybidae
Nothybus
Nothybus absens

description: Nothybus absens Lonsdale & Marshall, 2016
(Figs 1–19, 75)
Nothybus absens Lonsdale & Marshall, 2016: 12. Holotype (♀): China, Guangxi, type specimen lost and represented by photo voucher.
Diagnosis. Frons extensively velvety black on anterior half (Fig. 4). Wing (Figs 1, 2, 7) distally infuscated from level of dm-cu, with clear spots in cells r 2+3 and r 4+5 and a more diffuse patch in m 1; crossvein r-m with dark brown round spot; distal part of CuA 1 with elongate-oval dark brown area extending to dm-cu. Abdomen (Figs 9–11) mostly dark brown, except for the brownish yellow tergite 1; tergites 2 and 3 with diffuse lateral brownish yellow spot; tergite 4 brownish yellow with anterior margin and large posteromedial spot dark brown; and tergite 5 blackish brown with postero-lateral margin yellow.
Redescription. Male (Fig. 1). Body length 6.3–7.2 mm, wing length 5.6–6.5 mm.
Head (Figs 3–5) suborbicular, largely brownish yellow with grayish brown Pruinescence. Frons above antennae convex, with anterior pair of velvety black patches fused on anterior half. Face with dorsal half brownish yellow and ventral half brown and slivery tomentose, with medially shiny pale area. Parafacial dark brown. Ocellar tubercle black. Vertex with large pentagonal velvety black patch behind ocellar tubercle. Head bristles black; head with four pairs of long strong bristles: two fronto-orbital setae, one inner vertical seta and one outer vertical seta. Antenna dark yellow except the dark brown apical half of first flagellomere; arista dark brown, long and plumose. Proboscis yellow with dark brown lateral spot on labellum; palpus narrow and yellow.
Thorax (Fig. 6) mostly brownish yellow mottled with orange, grayish brown pruinescence. Postpronotum dark brown. Mesonotum dark brownish yellow with dark brown mid-longitudinal stripe and one pair of narrow brownish lateral stripes; mid-longitudinal brown stripe distinctly narrowing and ill-defined posteriorly. Scutellum dark brown except narrow posterior margin brownish yellow; subscutellum dark brown. Mesopleuron dark brownish yellow except posterior region; katepisternum with dark brown median spot. Thorax bristles black. Irregularly 6 rows of presutural acrostichal setulae in mid-longitudinal stripe; lateral stripe of 2–3 additional rows of setulae clearly delimited. Legs brownish yellow except extreme tips of femora dark brown, tibiae brownish black; tarsi brownish black except fore basitarsomere white with base brownish (Fig. 8). Hairs and bristles on legs black; mid coxa with one long outer bristle at base. Wing (Fig. 7) uniformly dark brown from level of dm-cu to distal margin, except for clear spots in cells r 2+3 and r 4+5 and a diffuse and elongate clear patch in m 1; crossvein r-m partially covered with dark brown round spot; CuA 1 with distal elongate-oval dark brown area extending to dm-cu. Calypter brownish with dark brown margin. Halter whitish with base slightly greyish.
Abdomen (Figs 9, 10) dark brown with gray brown pruinescence, except the brownish yellow tergite 1; tergites 2 and 3 with diffuse lateral brownish yellow spot; tergite 4 brownish yellow with anterior margin and large posteromedial spot dark brown; tergite 5 blackish brown with posterolateral margin yellow; and tergite 6 and terminalia light yellow. Sternites narrow and yellow. Abdomen bristles black. Sternite 6 with one pair of larger posterolateral setae.
Male genitalia (Figs 12–19, 75): Epandrium short and broad. Surstylus approximately 1/2 as long as height of epandrium and fused to it at posterior third; apical half strongly narrowed with minute setulae, apex slightly swollen with minute black denticles on inner surface. Cercus finger-like, slightly longer than surstylus. Hypandrium (Figs 15, 16) narrowly rounded anteriorly, more strongly arched medially. Pregonite distinctly curved with truncate apex and with two strong ventromedial setae. Basiphallus (Fig. 17) sclerotized laterally and along dorsobasal surface nearly forming a ring at base with venter incomplete. Distiphallus long with broad, undulating and membranous lateral margin and one pair of darker, diffuse medial ribbons; apex unified into shallow bulb, diverging into one pair of short, narrow, membranous tubules. Ejaculatory apodeme (Fig. 19) well developed with broad base.
Female (Fig. 2). Body length 6.9–7.8 mm, wing length 5.8–6.7 mm. Wing with clear spot in cell r 2+3 open to wing margin; abdominal tergite 3 entirely dark brown, tergite 6 brownish yellow with lateral blackish brown area (Fig. 11).
Material examined. CHINA: 1³, Yunnan, Lvchun, Mt. Huanglianshan (N22.88528°, E102.271175°), 20 Apr. 2018, leg. L. Wang (CAU); 1³ 2♀, Guangxi, Jinxiu, Mt. Dayaoshan (N39.986525°, E116.39857°), 14 Jun. 1982, leg. C. Yang (CAU).
Distribution. CHINA (Guangxi, Yunnan).
Remarks. Lonsdale & Marshall (2016) described N. absens from a female specimen that was lost (escaped) after it was photographed. Utilizing features visible in the photographs, they provided the following combination of diagnostic characters: anterior pair of velvety black patches on frons largely fused; scutum with a complete medial stripe; fore basitarsomere white with narrow dark annulus basally; wing with three clear, iridescent, linearly arranged spots subapically; abdominal tergite 4 brownish yellow with anterior margin and large posteromedial spot dark brown. They also refer to tergite 3 as entirely brown.
Newly available male and female specimens of N. absens are consistent with most of these diagnostic traits, but the coloration of wing and abdominal tergite 3 can now be described more accurately, including the following traits: cells r 2+3 and r 4+5 with a clear, iridescent subapical spot, respectively, with anterior one positioned more distally; middle of cell m 1 with a more diffuse and elongate clear spot; abdominal tergite 3 in male brown with diffuse, indistinct yellowish areas laterally.
N. absens resembles N. cataractus Lonsdale & Marshall, 2016, N. kempi (Brunetti, 1913) (Figs 49–55) and N. kuznetsovorum Galinskaya & Shatalkin, 2015 (Figs 68–74) in having the epandrium relatively broad and fused to posterior part of the surstylus; the surstylus is relatively short and wide but narrowed apically with minute setulae and black denticles on the inner-distal surface; and the distiphallus long and ribbon-like with one pair of relatively short tubules on an apical swelling. However, the cercus of N. absens is slender and slightly longer than the surstylus, which is unique among the N. kempi group, and the relatively narrowed epandrium and hypandrium, the shape of apical surstylus, and the truncated apex of pregonite, also unlike any of the above species.
description: Published as part of Zhou, Jiale, Marshall, Stephen A. & Yang, Ding, 2021, Synopsis of Nothybidae (Diptera: Brachycera) from China, with redescription of Nothybus absens Lonsdale & Marshall, pp. 201-223 in Zootaxa 4926 (2) on pages 203-207, DOI: 10.11646/zootaxa.4926.2.3, http://zenodo.org/record/4506019