Diacanthomyia okidoi Saigusa

Saigusa, Toyohei, 2015, A new genus and species of the subtribe Thyreophorina (Diptera, Piophilidae) from Japan, Zootaxa 4059 (2), pp. 319-334 : 325-331

Diacanthomyia okidoi Saigusa , sp. nov.

Male ( Figs 1 A, B, D, E). Coloration. Head ( Figs 2 A–C) tawny and mostly densely yellow to yellowish grey pollinose or pruinose; ocellar prominence and dorsal part of occiput black and light grey pollinose; frons reddish brown with narrow yellowish pollinose orbital bands; when viewed from in front frons with widely pollinose anterior marginal area connecting Y- or V-shaped pollinose marking extending posteriorly, when viewed from behind with pair of oval pollinose markings at middle. When viewed from in front, face densely yellow pruinose along eye margins, yellowish white pollinose on antennal groove; gena with oval yellow pollinose marking close to eye margin when viewed from in front. Compound eye dark to blackish brown. Antennal scape and pedicel tawny, latter densely yellow pollinose, appearing as apical bright yellow spot when viewed from in front; 1st flagellomere mat black. Maxillary palpus and proboscis tawny.

Thorax ( Figs 2 D, F) black; mesoscutum densely light grey pollinose with pair of brownish longitudinal bands separated by narrow greyish dorsomedian stripe between rows of dorsocentrals, more obscure brownish band lateral to dorsocentrals; small spot around socket of dorsocentrals and larger oval spot at mesal extremity of transverse suture polished black; when viewed from in front mesoscutum usually uniformly brown pollinose, with pair of small bright yellowish white pruinose spots appearing between 1st and 2nd dorsocentrals ( Fig. 2 F). Scutellum dark to blackish brown, with posterior part tawny in larger males, thinly light grey pollinose. Thoracic pleura light grey pollinose and partly pruinose.

Wing ( Figs 3 A, C, D) usually clear, occasionally slightly tinged with grey, r-m crossvein ( Fig. 3 C) surrounded entirely by circular dark marking; m-m crossvein ( Fig. 3 D) bordered with narrow dark bands; basal 1/2 of C, Sc, and R1 yellowish brown, other veins brown, more or less yellowish on basal part of wing; squama white with white marginal hairs. Halter yellowish white.

Legs dark brown, coxae grey pollinose, partly yellowish apically, trochanters yellow, femora narrowly yellowish on basal and apical parts, thinly greyish pollinose and subshiny; tibiae yellowish brown, polished, occasionally slightly darkened to brown; tarsi yellowish brown, hind metatarsus darkened dorsally, 2 distal tarsomeres of fore tarsus and apical tarsomere of mid and hind tarsi black.

Abdomen: Terga dark to blackish brown, terga 2–5 often tawny posteriorly and laterally; terga densely light grey pollinose except narrow polished black band along posterior margins of terga 2–4; sterna yellowish brown to dark brown and greyish pollinose.

Structure and vestiture. Head ( Figs 2 A–C) 0.94–1.04 times as long as high, 1.25–1.37 times as wide as long, almost as wide as thorax; frons 0.53–0.56 times as wide as head; gena 0.70–1.0 times as deep as compound eye height; occiput swollen posteriorly, distance between levels of posterior margin of compound eye and neck 0.30– 0.39 times as long as head length; horizontal diameter of compound eye 0.48–0.64 times as long as head. Hairs and bristles on head black; frons sparsely clothed with longish setae; anterior marginal setae of frons rather strong, 0.30–0.57 times as long as width of frons; posterior fronto-orbital bristle fairly strong, 0.37–0.45 times as long as head, anterior fronto-orbital bristles usually slightly shorter than posterior fronto-orbital; inner vertical bristle very strong, longest among head bristles, 0.58–0.74 times as long as head; ocellar bristle almost as strong and long as inner vertical bristle; postvertical bristle usually 0.8 times as long as inner vertical; 2 vibrissae strong, slightly shorter than outer vertical, 0.44–0.60 times as long as head; 1–2 subvibrissae almost always slightly shorter than vibrissa.

Thorax ( Fig. 2 D): Scutellum large, 0.44–0.54 times as long as scutum in largest males (length of scutum 1760– 1950 µ), small, 0.35–0.41 times as long as scutum in smallest males (length of scutum 1050–1200 µ); scutellum 0.74–0.91 times as long as basal width in largest males, 0.58–0.77 times as long as basal width in smallest males. Thoracic bristles and hairs black. Postpronotum clothed with hairs, in smaller males 1, occasionally 2 stronger setae mixed with hairs; presutural intra-alar, most of dorsocentrals, supra-alar and postalar bristles strong, 2 postsutural intra-alar rather weak, 1–2 notopleural and prescutellar acrostichal bristles weaker. Apical scutellar bristle well developed, thick and weakly curved inwards, subbasally nearly quadrate in cross-section, with dorsal surface flattened, 1330–1620 µ long and arising from distinct tubercle at posterolateral corner, and 1.5–1.7 times as long as scutellum in largest males, 810–950 µ long and from posterolateral corner, and 1.9–2.1 times as long as scutellum in smallest males; lateral scutellar bristle weak, arising from anterior 1/3 of lateral margin of scutellum and tip usually not extending beyond posterior margin of scutellum.

Wing ( Fig. 3 A) 2.9–3.3 times as long as wide; Costa ( Figs 3 E, F) with some spinules on middle 1/ 3 in some larger males; r-m crossvein short, connected with basal 0.50–0.64 of anterior vein of discal cell; apical free part of vein M4 nearly 1/2 as long as m-m crossvein; vein CuA+CuP ( Fig. 3 G, female wing) about 3/5 as long as distance from base to point of wing margin that it directs.

Legs: Fore femur strongly swollen from subbasal part to apical 2/3, then tapered distally, 0.25–0.28 times as thick as long in largest males, 0.22–0.25 times as thick as long in smallest males, clothed with hairs 1/4 to 1/3 as long as femur. Mid femur moderately swollen, 0.19–0.21 times as thick as long in largest males, 0.17–0.19 times as thick as long in smallest males, thickest at middle, tapered to tip; mid femur clothed with hairs 0.25–0.35 times as long as femur in largest males, and about 1/5 as long as femur in smallest males; several posterior hairs on subapical part longer and stronger. Hind femur rather slender, 0.17–0.18 times as thick as long in largest males, 0.16–0.17 times as long as smallest males, thickest at middle, tapered to both ends; hind femur clothed with long hairs 0.40–0.45 times as long as femur in largest males, 0.24–0.29 times as long as smallest males; some anteroventral hairs on apical 1/3 longer and stronger. Fore tibia clothed with long hairs 0.4–0.5 times as long as tibia in largest males, 1/4 as long as femur in smallest males. Mid tibia clothed with long hairs nearly 1/2 as long as tibia in largest males, 1/3 as long as smallest males. Hairs of hind tibia longest, 0.5–0.6 times as long as largest males, and 1/4–1/3 as long as smallest males. Most of long hairs of legs of larger males frizzled apically, while those of smaller males usually strait apically.

Abdomen: Terga densely clothed with long hairs including posterior marginal hairs of 3rd tergum but disc of terga 1–3 sparsely clothed only with short hairs. Long hairs of smaller males about 1/2 as long as width of terga and straight to tip, those of larger males nearly as long as width of terga and mostly apically frizzy. Sterna sparsely clothed with short straight hairs. Hairs black, those on lateral parts of terga and sterna often yellowish. Male genitalia as described and illustrated in generic characters of Diacanthomyia .

Length: Body 3.2–6.7 mm; wing 3.9–6.9 mm. Range of body size is extraordinarily large for Diptera , almost certainly caused by quantity and quality of food in larval stage.

Female ( Fig. 1 C). Coloration. Similar to male, differing as follows: Abdominal terga 1–5 black, fairly densely grey pollinose, with polished posterior marginal band; occasionally band produced forward along dorsomedian line, rarely continues to anterior margin of terga; posterior marginal area of tergum 5 brown; tergum 6 yellowish brown, thinly grey pollinose; tergum 7 polished dark to blackish brown. Abdominal sterna 1–4 blackish brown; sterna 5–7 yellowish brown; lateral parts of sterna more or less paled; abdominal sterna thinly grey pollinose. Terminalia yellow.

Structure and vestiture. Head almost as in male. Postpronotum with 2 bristles, dorsal one directed dorsally, ventral one posterolaterally. Scutellum not dilated as in male, trapezoidal in shape, 0.31–0.36 times as long as scutum, 0.63–0.75 times as long as basal width; scutellar bristles long and fine, apical scutellar bristles 960–1400 µ long, 2.2–2.8 times as long as scutellum, lateral scutellar bristles 1.5–2.1 times as long as scutellum, with tip extended posteriorly well beyond posterior margin of scutellum. Wing ( Fig. 3 B, G) as in male, costa without spinules.

Legs similar to those of smaller males; hairs shorter, some of long hairs of largest females weakly frizzy apically. Fore femur 0.22–0.26 times as long as thick, with hairs 1/4–1/3 as long as femur; mid femur 0.16–0.18 times as long as thick, with hairs about 1/4 as long as femur, ventroproximal seta 1/3 as long as femur; hind femur 0.14–0.15 times as long as femur, with hairs 0.2–0.28 times as long as femur and ventroproximal seta slightly longer, with 2–3 anteroventral setae 1/3 as long as femur and more or less bristle-like. Tibiae clothed with hairs about 1/4 as long as tibiae. Tarsi shorter setose than in male.

Abdomen: Terga 1–5 with sparse short setae nearly 1/5–1/4 as long as terga on disc, fairly dense with long straight setae about as long as terga laterally; terminalia posterior to 5th segment as described and illustrated in generic characters of Diacanthomyia .

Length: Body 4.2–6.3 mm; wing 4.6–6.2 mm.

Type material. HOLOTYPE ♂. Kokoserindô 390m, Inokodani, Suki, Kobayashi-shi, Miyazaki Pref., Kyushu, Japan, Dec. 26–28, 2007, from decayed head of a deer, T. Saigusa col.(KU).

Paratyp e: Kyushu, Miyazaki Pref.: 4 ♂, Inokodani, 365–460 m, Kobayashi-shi, 25.ii.2004, H. Okido col.; 3♂, 2♀, Inokodani, 19–20.iii.2007, from decayed carcass of deer, T. Saigusa col.; 29 ♂, 3♀, same data as holotype; 5♂, 2♀, Inokodani 367 m, Suki, Kobayashii, 7.iii.2008, T. Saigusa col.; 29♂, 22♀, Urasedani, 400 m, Inokodani, Suki, 17–18.xii.2008, T. Saigusa col.; 33♂, 13♀, Inokodani 367–500 m, Suki, Kobayashi, 22– 23.xii.2009, T. Saigusa col. Kyushu, Kumamoto Pref.: 7♂, 4♀ (in 70% glycerol), Mt. Ichifusa-yama (740 m), Mizukami, 15.iii.2014, attracted to a decayed meat trap, K. Nishi col.. Honshu, Saitama Pref.: 9♂, 27♀ (in 70% glycerol), Name-sawa (900 m), Univ. Tokyo Chichibu Forest, Ôtaki, Chichibu-shi, 22.ii.–22.iii.2015, attracted to decayed meat trap, T. Tago col. Most of paratypes are in the collection of KU. One pair of paratypes from Miyazaki will be donated to HU, NHM and OMN, two pairs of paratypes from Miyazaki to AM, NMD, SUM, TAU, UAH, UR and USNM, two pairs of paratypes from Miyazaki Pref. and one pair of paratypes in glycerol from Saitama Pref. to CNC.

Type-locality. Inokodani 390 m, Suki, Kobayashi-shi, Miyazaki Pref., Kyushu, Japan.

Distribution. Honshu (Kanto District), Kyushu, Japan.

Etymology. The specific name is dedicated to Dr. H. Okido, the discoverer of this species.

Habitats. This species lives in cool temperate to warm temperate forests in Honshu and Kyushu. In southern Kyushu this species was found in evergreen broad-leaved forests along Inokodani (367–500 m; Urasedani, 32°06'50.478"N 131°00'39.126"E, 416 m alt.) and Iwasegawa (380–520 m; Tsuruyashiki 32°07'45.826"N 130°58'24.947"E, 521 m alt.) in Kobayashi-shi, Miyazaki Pref. and it was attracted to a trap using decayed chicken meat as bait set in forest mixed with evergreen and deciduous broadleaved trees at Mt. Ichifusa-yama (32°18'52.467"N 131°04'41.954"E, 751 m alt.), Kumamoto Pref. In central Honshu, this species was attracted to a trap using decayed chicken and pork as bait set in deciduous broad-leaved forest (900 m) at Namesawa (35°55'27.469"N 138°49'36.958"E, 923 m alt.), The University of Tokyo Chichibu Forest, Ôtaki, Chichibu-shi, Saitama Pref.

Figures

FIGURE 1. Diacanthomyia okidoi sp. nov. A, B, D, E: male; C: female. A: holotype, one of largest males; B: paratype, one of smallest males; C: paratype, one of largest females; D: paratype, dorsolateral aspect; E: paratype, lateral aspect.

FIGURE 2. Diacanthomyia okidoi sp. nov. A: male head, anterior aspect; B: ditto, lateral aspect; C: ditto, dorsal aspect; D: male thorax, dorsal aspect (white circle is head of pin); E: female thorax dorsal aspect; F: male head and thorax, anterodorsal aspect showing pair of whitish pruinose spots at mesal extremity of transverse sutures.

FIGURE 3. Wing of Diacanthomyia okidoi sp. nov. A: male wing; B: female wing; C: area around r-m crossvein of male wing; D: area around m-m crossvein of male wing; E: part of costa with spinules of male wing; F: part of costa without spinules of male wing; G: basal part of female wing.