Dichetophora nigricorpa, Son & Suh, 2021

Son, Yeongjin & Suh, Sang Jae, 2021, First record of the snail-killing fly genus Dichetophora Rondani (Diptera: Sciomyzidae) in Korea, with descriptions of two new species, Zootaxa 5068 (1), pp. 125-132 : 129-132

Dichetophora nigricorpa sp. nov.

( Figs. 3–4 )

Diagnosis. General body color black; occiput blackish with whitish pruinescence; 1 pair of scutellar setae; wing dark with numerous round hyaline spots, all veins black except C, Sc, R 1, and R 2+3 yellow and M 4 yellow at apex; all tarsi blackish brown; knifelike surstylus long, narrow, with sharp black tip at apex.

Description (male). Head ( Fig. 3A–C ). Frons brownish, shining; mid frontal stripe yellowish brown, reaching anterior margin of frons; narrow fronto-orbital margin silver; black spot at base of fronto-orbital setae, anterior spot much larger than spot at base of posterior fronto-orbital seta; occiput black covered with whitish pruinescence, with black setae laterally on both sides and a cluster of stout setae in the middle; gena white, without setae; orbitoantennal spot large, black; lunule shining darkish brown; palpus brownish, setose; antenna porrect; postpedicel with brownish black setulae becoming yellowish setulae basally, similar length to that of pedicel; pedicel setose on ventral and dorsal margins, with 1 longer seta at the anterior dorsal margin; pedicel about 7 times as long as scape; arista whitish yellow with white pubescence; 2 fronto-orbital, 1 ocellar, 1 postocellar, 1 inner vertical, and 1 outer vertical setae present.

Thorax ( Fig. 3C–D ). Grayish black, covered with black setae and whitish pruinescence; 2 medial black vittae and 2 lateral interrupted black vittae on scutum; 1 presutural supra-alar, 1 dorsocentral, 1 scutellar, 1 postpronotal, 1 supra-alar, 2 postalar, and 2 notopleural setae present; presternum, anepisternum, anepimeron, meron, and katatergite bare; katepisternum entirely setose, with cluster of longer setae on the ventral margin; anterior spiracle yellow, posterior spiracle brown.

Wing ( Fig. 3F ). Yellowish anteriorly, grayish posteriorly, covered with rounded hyaline spots except basal 1/4 of wing immaculate; anal cell blackish, immaculate; 8–10 black spots in cell r 1; reticulation not reaching wing margin in the three cells between R 2+3 and M 4; all veins black except C, Sc, R 1, and R 2+3 yellow and M 4 yellow at apex; crossvein r-m straight; costal vein clear and yellow; halter black basally and yellow apically.

Leg ( Fig. 3C ). Pale yellow and brown, covered black short setae; all coxae with cluster of long setae at ventral apex; fore coxa yellowish white; mid and hind coxae blackish brown; basal two-thirds of fore femur whitish yellow, distal third of fore femur brown,; basal half of mid and hind femora whitish yellow, distal half brownish yellow; all tibiae with 1 pre-apical seta; fore tibia whitish yellow, becoming brownish yellow toward apex; mid tibia yellowish; hind tibia brownish, darkened at distal apex; all tarsi yellow, darkened toward apex; fore femur with 5–6 long setae on the dorsal margin; hind femur with 10–12 spines on ventral margin.

Abdomen ( Fig. 3C , Fig. 4 ). Glossy; tergite 1 with cluster of stout setae; tergites 1–4 black, and tergite 5 dark brown, all tergites with yellow lateral stripe; sternites brown, covered with short setae; sternites 2–4 with long setae on posterior margin; sternite 5 divided, with cluster of short black setae and 3 long setae on each side; tergite 5 and syntergosternite 7+8 dark brown; syntergosternite 6 asymmetric; syntergosternite 7+8 round, setose on dorsal half in posterior view; epandrium suboval, setose; cercus prominent in lateral view, with short pale setulae and long black setae; knifelike surstylus long, narrow, ventral apex sharply pointed and darkened, 3–4 setae on dorsal margin; knob-like projection at basal margin of surstylus subrectangular, covered with black setae; pregonite sharply pointed in lateral view; basiphallus pointed on both side; phallus asymmetric in both posterior and lateral view, right side with rounded structure in posterior view, in lateral view left side with pointed membranous posterior margin and rolled membranous anterior margin.

Female. Similar to male but black spot at base of anterior fronto-orbital seta larger than in male; apical section of vein M 4 yellowish; anal cell yellowish brown; 8–10 black spots in cell r 1; all tergites black; yellow lateral stripe on abdomen narrower than in male.

Body length: male: 8.7–8.8 mm, female: 8.7–8.8mm.

Wing length: male: 6.7–6.8 mm, female: 6.8–6.9 mm.

Type material. Holotype: male, Mt. Wantaeksan , Yeongwol-eup , Yeongwol-gun, Gangwon-do, 37°12′03″N 128°33′31″E, 23.VII.2018, S.J. Suh. Paratypes: 1 female, Mt. Mindungsan , Nam-myeon, Jeongseon-gun, Gang- won-do, 37°15′17″N 128°46′38″E, 02.X.2016, S.J. Suh ; 1 female, Seonjaryeong , Pyeongchang, Gangwon-do, 37°41′46″N 128°45′13″E, 19.IX.2020, S.J. Suh ; 1 female, Mt. Sobaeksan , Samga-ri , Punggi-eup, Yeongju-si, Gyeongsangbuk-do, 36°54′55″N 128°30′38″E, 22.IX.1985, S.J. Suh.

Distribution. Korea (Central, new record).

Remarks. The new species differs from D. kumadori in having separate black spots on each fronto-orbital socket ( Fig. 3B ) and in features of the male genitalia ( Fig. 4 ). It is distinguished from the other Palearctic species ( D. finlandica , D. meleagris , and D. obliterata ) by its black body color ( Fig. 3C ) and the structure of sternite 5 ( Fig. 4G ). It is distinguished from the Asian species, D. intermedia , by the presence of ocellar setae ( Fig. 3 A-B).

Variation. A female specimen (paratype) has three scutellar setae (asymmetric).

Etymology. The specific name is named for the black body-color.

Figures

FIGURE 3. Dichetophora nigricorpa sp. nov. (male, holotype).A, head and antenna in left lateral view; B, head in dorsal view; C, habitus in left lateral view; D, scutellum in dorsal view, male; E, scutellum in dorsal view, female. Scale bars: A–B, D–E = 0.5 mm; C, F = 1 mm. Abbreviations. fo: fronto-orbital seta; oc: ocellar seta; iv: inner vertical seta; ov: outer vertical seta; po: postocellar seta.

FIGURE 4. Postabdominal structures of Dichetophora nigricorpa sp. nov. (male, holotype). A, epandrium and surstylus in posterior view; B, postabdomen in right lateral view; C–E, phallus in left (C) and right (E) lateral and posterior view (D); F, hypandrium, pregonite and postgonite in left lateral view; G, sternite 5. Scale bars: A–B = 0.2 mm; C–G = 0.1 mm. For abbreviations, refer to Figure 2.