Dactylolabis (Dactylolabis) diluta Alexander 1922
Creators: name: Kato, Daichi
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Limoniidae
Dactylolabis
Dactylolabis diluta

description: Dactylolabis (Dactylolabis) diluta Alexander, 1922
(Figs 1, 2, 6A)
Dactylolabis diluta Alexander 1922: 183.
Type locality: Japan, Honshu, Gifu.
Dactylolabis (Dactylolabis) diluta Alexander 1953: 81; Alexander 1954: 293; Nakamura 2014: 9; Oosterbroek 2023.
Type material examined. HOLOTYPE, male, JAPAN, Honshu, Gifu, 20.IV.1921, K. Takeuchi (USNM). Other examined material. JAPAN: [Honshu] 1 female, Aomori, Nishimeya-mura, Kawaratai, Ôkawa Path, altitude 130 m, N40.5006°, E140.2040°, 14.V.2013, D. Kato (BLKU); 1 male, same data as previous except 7.V.2014; 1 male, same data as previous except 13.V.2014; 2 males, Aomori, Hirosaki-shi, Sôma Path, altitude 390 m, N40.4947°, E140.4023°, 24.V.2013, D. Kato (BLKU); 1 male, Aomori, Fukaura-machi, Mt. Takanio-yama, altitude 140 m, N40.6899°, E140.1028°, 2.V.2014, D. Kato (BLKU); 1 female, Niigata, Nagaoka-shi, Karuizawa, N37.4417°, E138. 9342°, 9.IV.2016, G. Mashima (BLKU); 1 male, Niigata, Shibata-shi, Takidani, altitude 204 m, N37.8155°, E139.4629°, 11.V.2022, D. Kato (BLKU); 2 males, 3 females, Niigata, Tokamachi-shi, Matsunoyama, Echigo-Matsunoyama Museum of Natural Science, ‘Kyororo’, altitude 310 m, N37.0995°, E138.6163°, 4.IV.2020, D. Kato (BLKU); 1 male, same data as previous except 9.V.2020; 35 males, 19 females, same data as previous except 9–16.V.2021, MT; 19 males, 37 females, same data as previous except 16–23.V.2021, MT; 4 males, 5 females, same data as previous except 23–30.V.2021, MT; 1 male, 2 females, Toyama, Nanto-shi, Tatenoharahigashi, Johana Service Area, altitude 215 m, N36.5033°, E136.8729°, 13.IV.2014, D. Kato (BLKU); 1 male, Omi (Shiga), Mt. Ibuki, N35.417°, E136.400°, 13.IV.1958, T. Mishima (USNM); 4 females, Ôsaka, Izumisano-shi, Inunakisan Spa, altitude 250 m, N34.3398°, E135.3837°, 16.IV.2014, D. Kato (BLKU); 1 female, Tottori, Kurayoshi-shi, Sekiganechô-Nozoe, Mt. Karasuga-sen, altitude 1000 m, N35.3535°, E133.5857°, 17.V.2015, D. Kato (BLKU); 1 female, Okayama, Maniwa-shi, Hiruzen-Shimotokuyama, altitude 780 m, N35.3293°, E133.5972°, 1.V.2016, D. Kato (BLKU); 1 male, Yamaguchi, Iwakuni-shi, Nishiki-machi-Ôno, Mt. Shôjô-yama, altitude 330 m, N34.2999°, E131.9375°, 2.V.2016, D. Kato (BLKU). [Shikoku] 1 male, Ehime, Matsuyama, Sugitate, N33.861°, E132.848°, 18.IV.1953,T.Mohri (USNM); 1 male, Ehime, Omogokei, 800 m, N33.72°, E133.09°, 10.V.1952, Ishihara (USNM); 2 males, Ehime, Tôon-shi, Kamihayashi, near Shiraito Waterfall, altitude 560 m, N33.7370°, E132.8969°, 20.IV.2014, D. Kato (BLKU); 1 female, Ehime, Tôon-shi, Kawanouchi, altitude 440 m, N33.766°, E132.970°, 20.IV.2014, D. Kato (BLKU); 2 males, Ehime, Tôon-shi, Yamanouchi, Akako-keikoku Valley, N33.876°, E132.945°, 27.IV.2018, R. Toda (BLKU); 4 males, Tokushima, Higashimiyoshi-chô, Higashiyama, Ogawadani-gawa River, altitude 340 m, N34.0883°, E133.8799°, 21.IV.2014, D. Kato (BLKU); 2 males, Tokushima, Higashimiyoshi-chô, Nishisyô, Kamodani-gawa River, altitude 170 m, N34.0153°, E133.9432°, 21.IV.2014, D. Kato (BLKU); 2 males, Tokushima, Miyoshi-shi, Higashiiya-Sugeoi, near Nagoro Dam, altitude 920 m, N33.8518°, E134.0234°, 29.IV.2016, D. Kato (BLKU); 1 male, Miuma-shi, Koyadaira, altitude 1340 m, N33.8754°, E134.0957°, 30.IV.2016, D. Kato (BLKU); 2 males, Kagawa, Mannô-chô, Myôjin-gawa River, altitude 480 m, N34.0940°, E134.0143°, 21.IV.2014, D. Kato (BLKU). [Kyushu] 1 male, Fukuoka, Kitakyushu-shi, Kokuraminami-ku, Dôbaru, Takinoguchi-gawa River, N33.790°, E130.817°, 17.IV.2019, R. Toda (BLKU); 3 males, Fukuoka, Miyako-machi, Saigawa-Hobashira, Notôge Pass, altitude 740 m, N33.4956°, E130.9615°, 22.IV.2016, D. Kato (BLKU); 2 males, 4 females, Saga, Saga-shi, Fuji-machi-Sekiya, Kase-gawa River near Hokuzan Dam, altitude 320 m, N33.4332°, E130.2321°, 12.IV.2015, D. Kato (BLKU). [Nansei Islands] Yakushima Is: 4 males, 2 females, Yakushima-chô, near Shirataniunsui-kyô Valley, altitude 600 m, N30.3839°, E130.5728°, 25.IV.2018, D. Kato (BLKU).
Redescription. Male. Body length 6.0– 10.2 mm, wing length 7.5–11.4 mm.
Head. Grey, tinged with ocherous, sparsely covered with yellow and brown setae. Anterior part of vertex with narrowest part as wide as eye in dorsal view; vertex posterior to eye slightly shorter than eye. Antenna generally brown to brownish black, about 2.5 times length of head. Scape weakly greyish by pruinosity, 3–4 times as long as wide. Pedicel twice longer than wide and half as long as scape, distal part distinctly broader. Flagellomeres long oval, about 1/3 as wide as long on segment 1, gradually decreased in size toward apical segment, base of flagellomere 1 often narrowly yellowish; each segment with about five verticils, at most as long as corresponding segment, and covered with pale pubescence, about 1/4 length of corresponding segment; pubescence on apical 1–2 flagellomere indistinct. Rostrum slightly darker than vertex by sparser pruinosity, 3/4 length of scape. Palpus dark brown to black; palpomere 1 small, roundish; palpomeres 2–5 almost same in length, each segment three times as long as palpomere 1; palpomere 4 slightly broader than other segments. Labellum dark brown to black.
Thorax. Notum subnitidous by relatively sparse pruinosity, sparsely covered with relatively long, yellow to brown setae. Pronotum grey, weakly tinged with ocherous; postpronotum sometimes yellowish or brownish laterally. Mesonotum ocherous to brown; prescutum and presutural scutum with two indistinctly darker stripes at middle, often fused with each other, extending from near anterior end to near transverse suture; postsutural scutum with interspace between scutal lobes brighter by denser pruinosity. Mediotergite dark in dorsal view. Pleuron dark grey; dorsopleural membrane brighter or yellowish; laterotergite and around base of wing sometimes brownish. Wing (Fig. 1B) tinged with brown, prearcular region yellowish. Obscure small brown spot present at origin of Rs, crossvein sc-r, tip of R 2, and fork of M 1+2; spot at tips of R 2 and fork of M 1+2 often indistinct; cord and outer end of cell dm vaguely seamed with brown. Rs weakly curved near base; cell dm 1.8–2.5 times as long as wide. Legs covered with short blackish setae. Coxae and trochanters yellow to ocherous, coxae dusted with grey in various degrees, sometimes entirely grey. Femora and tibiae dark brown on each distal part, gradually turning into yellow toward base of each segment in darker specimens, or tip of each segment narrowly dark in lighter colored specimens. Tarsi dark brown. Halter yellow to whitish yellow.
Abdomen. Dark brownish grey, sparsely covered with yellowish setae.
Hypopygium (Figs 1C–I). Epandrium (Fig. 1C) cylindrical, longer than wide. Hypandrium (Fig. 1D) widely and slightly convex posteriorly at middle of posterior margin. Proctiger (Fig. 1C) roughly squarish, lateral lobe (Fig. 1E) long triangular, obtuse at tip, about 1.5 times as long as wide. Gonocoxite (Fig. 1F) 1.5–1.7 times as long as wide, and 0.6–0.7 times as long as epandrium, widest on basal 1/3 and narrowest at middle. Outer gonostylus (Fig. 1G) long finger-shaped, basally widened, about as long as gonocoxite and inner gonostylus, slightly wider than inner gonostylus; inner gonostylus (Fig. 1G) slightly sinuous, tip pointed. Interbase (Figs 1H–I) with middle part fused and forming narrow band, bearing pair of blade-shaped ventral lobes, distal 1/3 slightly broader and narrowed to tip; posterior margin of interbase with indistinct U-shaped notch at middle; lateral arm narrow and almost straight. Paramere (Figs 1H–I) slender, weakly curved outward, outer margin with serrate area near base. Aedeagus (Figs 1H–I) cylindrical, relatively stout, distal part slightly curved ventrally, tip ending at level of posterior end of interbase. Sperm pump (Figs 1H–I) large, slightly shorter than and about three times as wide as aedeagus, lateral margin with fin-like extension directed anteriorly. Ejaculatory apodeme (Figs 1H–I) with each arm large and wide, directed anteriorly.
Female. Body length 7.0– 8.5 mm, wing length 8.3–10.2 mm. Generally resembling male.
Female terminalia (Figs 2A–G). Generally dark brown. Tergite 10 brown, yellow apically. Cercus (Fig. 2B) yellow, about as long as tergite 10, weakly constricted near middle in lateral view, densely covered with long hair-like setae; ventral margin at distal 1/5 roundly produced; distal 1/5 gradually narrowed to tip. Sternite 8 (Fig. 2E) squarish, slightly longer than wide in ventral view. Hypogynial valve wide blade-shaped, about 1.8 times as long as sternite 8, apical 1/3 strongly narrowed in ventral view; tip ending near level of middle of cercus. Sternite 9 (Figs 2C–D) with anterior margin deeply notched at middle, posterior margin with ventrally-directed lobe at center, posterolateral part extended into tongue-shaped lobe. Genital frame (Figs 2F–G) with genital fork slender rod-shaped, arched in dorsoventral axis, about twice as long as remainder of genital frame, anterior part directed anteroventrally; lateral arm oval, central part distinctly produced; common spermathecal duct short, if bent anteriorly, furcation point situated near base of genital fork.
Distribution. Japan (Honshu, Shikoku, Kyushu, and Nansei Islands (Yakushima Island)) (Fig. 6A) (Oosterbroek 2023).
Remarks. This species is similar to a West Palaearctic species D. (D.) transversa (Meigen, 1804) based on the general appearance and hypopygium, but is differentiated from it by the following characters: dark markings on wing obscure, distal part of CuA without dark area (Fig. 1B) (distinct, borders of markings clearer, distal part of CuP with distinctly dark area in D. transversa); hypopygium with epandrium cylindrical, longer than wide (Fig. 1D) (roughly trapezoid in dorsal view, shorter than wide in D. transversa); female terminalia with cercus wider on basal half (Fig. 2B) (wider on distal half in D. transversa).
description: Published as part of Kato, Daichi, 2023, Taxonomic study of the genus Dactylolabis Osten Sacken, 1860 of Japan (Diptera: Limoniidae), pp. 227-240 in Zootaxa 5375 (2) on pages 228-232, DOI: 10.11646/zootaxa.5375.2.4, http://zenodo.org/record/10184348