Acerocnema saurischia, Han & Shin, 2025

Han, Sangjin & Shin, Seunggwan, 2025, First records of the genus Acerocnema Becker (Diptera: Scathophagidae) from South Korea, with a new species and a newly recorded species using DNA barcodes, Zootaxa 5653 (3), pp. 440-450 : 445-447

Acerocnema saurischia sp. nov.

( Figs 1A–B, D–E, G ; 2A–D ; 3 )

Type material examined. HOLOTYPE ♂ Republic of Korea: [GG]: Gyeonggi-do, Mt. Taehwasan, Docheokmyeon , 37°18’43.3”N 127°18’33.2”E, malaise 20.IV–22.III.2023, Han S., Shin S., SNUE02361 ( SNUE) . PARATYPES (1♂, 34♀♀), 1♂, [GW]: Gangwon-do , Mt. Chiaksan , Panbu-myeon, Wonju-si, 37°15’03.6”N 128°01’39.6”E,malaise 14. V –30.III.2022, Han S., Shin S., SNUE00760 ( SNUE) , 7♀♀,ditto as holotype SNUE02360 , SNUE02362 , SNUE02363 , SNUE02364 , SNUE02365 , SNUE02366 , SNUE02367 ( SNUE) , 2♀♀, ditto but 31. V – 20.IV.2023, SNUE02357 , SNUE02358 ( SNUE) , 1♀, ditto but 10. V –30.III.2022, SNUE01554 ( SNUE) , 4♀♀, ditto but 15.IV–2.IV.2021, SNUE00041 , SNUE00747 , SNUE00748 , SNUE00749 ( SNUE, but SNUE00749 deposited in HNIBR) , 1♀, [GW]: Gangwon-do , Yongdae Natural Recreational Forest, Buk-myeon, Inje-gun, 38°14’27.2”N 128°20’11.5”E, malaise 22.IV–23.III.2023, Han S., Shin S., SNUE02401 ( SNUE) , 19♀♀, ditto as holotype but 18–4.IV.2024, SNUE02860 , SNUE02861 , SNUE02862 , SNUE02863 , SNUE02864 , SNUE02865 , SNUE02866 , SNUE02867 , SNUE02868 , SNUE02869 , SNUE02870 , SNUE02871 , SNUE02872 , SNUE02873 , SNUE02874 , SNUE02875 , SNUE02876 , SNUE02877 , SNUE02878 ( SNUE) .

Diagnosis. This species can be distinguished from congeneric species by the following characters: yellow gena and postgena, well-developed vibrissal angle, black postpedicel, yellow palpus, thorax with microtrichia, scutum with small shiny spots on both pre- and postsutural intra-alar lines, vein R 1 without dorsal setulae, yellow legs, and male surstylus extended and enlarged apically.

Description. Male. Body primary color shiny black; pleura shiny black; scutum shiny black; entire body pruinose except for scutellum and abdomen ( Fig. 1A–B, D–E ). All setae yellowish white.

Head. Face and parafacial yellow transitioning to black toward apex; gena and postgena yellow with yellowish white setulae, genal width about one third of vertical diameter of eye. Frontal vitta matt, orangish yellow, yellowish white apically. Fronto-orbital plate and ocellar triangle shiny black; occiput shiny black with yellowish white setulae. Fronto-orbital plate with 4–5 inclinate frontal setae, 3 lateroclinate orbital setae, 1 pair of lateroclinate orbital setae, 1 pair of short divergent postocellar setae, 1 long inclinate inner vertical seta and 1 short lateroclinate outer vertical seta. Well-developed vibrissal angle with 1 strong vibrissa with 2 short supravibrissal setae and 1 strong subvibrissal setae, all yellow. Antenna with postpedicel black, bean-shaped, covered with very fine microtrichia, approximately as long as the length of arista; scape and pedicel blackish brown; arista yellow on basal half and black and thinner on apical half, short pubescent apically. Palpus yellow, long, almost filiform, slender on basal half and slightly dilated on apical half with white hairs over surface; proboscis slender, somewhat stout on the basal part, with reduced labella with whitish yellow setulae.

Thorax ( Fig. 1D–E ). Black with an overall shiny surface, but largely obscured by white microtrichia and all setae yellowish white; scutum covered with white microtrichia and white setulae, partially with two pairs of small round shiny spots along pre- and postsutural intra-alar lines ( Fig. 1G ); acrostichal setae in 2–5 rows, shorter and finer than dorsocentrals; 1–2 presutural and 3–4 postsutural dorsocentral setae; 1 postpronotal seta; 0 presutural intra-alar setae; 1 presutural supra-alar; 2 notopleural setae; 0 postsutural intra-alar setae; 2 postsutural supra-alar setae; 2 postalar seta; 1 pair of strong basal scutellar setae and 1 pair of strong convergent apical scutellar setae. Anterior margin of presutural dorsocentral lines with 3 erect white setulae. Pleura shiny black, covered with microtrichia except dorsal half of anepisternum and anepimeron. Proepisternum with 2 whitish yellow proepisternal setae, covered with setulae. Proepimeron with 1 long seta. Anepisternum covered with setulae in posterior half, with 2 long posterior setae. Katepisternum with one strong posterodorsal seta and setulae ventrally. Anepimeron bare. Thoracic spiracles with short yellow hairs.

Wing. Clear, R 1 bare apically on dorsal surface. Calypters whitish with yellowish fine marginal hairs. Halter yellowish.

Legs. Entirely setose. Fore and mid coxae yellow, hind coxae brownish black; femora yellow; tibiae yellow; tarsi yellow, darkened apically from hind tarsomere 3. Setae pale yellow but black on tarsi. Fore femur with dense dorsal hairs. Fore tibia with 1 apical dorsal seta, 1 apical anterodorsal seta, 1–2 anterodorsal seta on apical 1/3. Mid tibia with 1 anterior seta on apical 1/5, 1 preapical dorsal seta, 1 apical anterodorsal seta, 1 apical anterodorsal seta, 1 anterodorsal seta on apical 1/3, 1 preapical posterior seta. Hind tibia with 1 preapical dorsal seta, 1 anteroventral seta on apical 1/4, 1 apical ventral seta, 1 apical anterodorsal seta, 2 anterodorsal seta on apical 2/5 and 3/5, 1 apical posterodorsal seta, 2 posterodorsal seta on apical 2/3 and 1/2.

Abdomen. Shiny black covered with pale setulae over surface. Abdominal sternite shiny black. Sternite 5 Ushaped ( Fig. 2A ), pale yellow, lobes sharply triangular, divergent; lobes with stout, scattered pale white setae over surface.

Terminalia ( Fig. 2B–D ). Epandrium shiny black, with long dense setae. Surstylus pale yellow, slender, and extended, ladle-shaped on lateral view, prominently enlarged and blackish in apical part, with setulae along inner margin and scattered setae at inner apex. Cercus pale yellow, comprising two sclerotized sections; dorsal section somewhat triangular on posterior view, with dense long, stout setae over surface; ventral section slender, extended in posterior view, broad in middle and narrower apically in lateral view, with dense setulae from apical 1/3 to subapical inner surface and black at apex. Pregonite wider than postgonite in lateral view, severely crooked ventroapically, dense hairs over surface from beginning of bend. Postgonite long and slender, bare and slightly crooked ventroapically. Epiphallus slimmer and slightly shorter than pregonite. Phallapodeme enlarged, fan-shaped, not digitiform. Hypandrium slightly arched apically, not thicker and stouter than that of A. flavifrons .

Female. Parafacial yellow; postpedicel very slightly slenderer than male; abdominal segments (tergites and sternites) VII to VIII compressed, triangle-shaped in lateral view and sternite VIII strongly sclerotized, indented in the apical tip ( Fig. 3 ).

Distribution. Republic of Korea (new record)

Etymology: The species name is derived from the Greek words “sauros” (lizard) and “ischion” (hip joint), referencing the resemblance of the male terminalia shape, in lateral view, to a saurischian dinosaur hip joint.

Remarks. This new species is similar to A. kishimotoae Iwasa , but differs by its yellow postgena (dark brown in A. kishimotoae ), entirely yellow palpus (apically brown in A. kishimotoae ), ladle-shaped surstylus (club-shaped in A. kishimotoae ( Iwasa 2014, figs 2–3)). In Ozerov & Krivosheina (2018), A. saurischia sp. nov. keys to A. paradoxopyga Stackelberg , but differs by its shiny scutellum (grey dusted in A. paradoxopyga ) and yellow legs (hind femur black, fore and mid femora black at least on basal half in A. paradoxopyga ).

Bionomics. Adults were collected by Malaise traps surrounded by a flower community of Corydalis from March to April ( Fig 4A–C ).

Figures

FIGURE 1. Acerocnema spp., habitus lateral and dorsal views. A–B, D–E, G, Acerocnema saurischia sp. nov., habitus of male (A) and female (B), dorsal view of male (D) and female (E), left half of scutum of male (G); C, F, H, Acerocnema flavifrons, habitus of male (C), dorsal view of male (F), left half of scutum of male (H). Scale bar: 1 mm (A–F). White arrows in (G) indicate partial shiny spots on scutum of Acerocnema spp. Acerocnema saurischia sp. nov. has smaller shiny spots than those of A. flavifrons.

FIGURE 2. Male sternite 5 and terminalia of Acerocnema spp.A–D, A. saurischia sp. nov., male sternite 4 and 5 in ventral view (A); B–C, male genitalia, epandrium, cerci, surstyli in lateral view (B), in posterior view (C), adeagus in lateral view (D). E–H, A. flavifrons, male sternite 5 in ventral view (E); F–G, male genitalia, epandrium, cerci, surstyli in lateral view (F), in posterior view (G), phallus in lateral view (H). Scale bar: 0.25 mm (A, D–E, H); 0.5mm (B–C, F–G). Abbreviations: cerc—cercus; d sec cerc—dorsal section cercus; epiph—epiphallus; pgt—postgonite; ph—phallus; phap—phallapodeme; pregt—pregonite, st—sternite; v sec cerc—ventral section cercus.

FIGURE 3. Female abdomen of A. saurischia sp. nov. in lateral view. Scale bar:1 mm. Abbreviations: cerc—cercus; epiprct— epiproct; hyprct—hypoproct; spmth—spermathecae; st—sternite; tg—tergite.

FIGURE 4. A group of flowers of Corydalis spp. occurring near Malaise traps in the early spring. (A) Corydalis ambigua Cham & Schltdl, (B–C) Corydalis speciosa Maxim. Photographs were taken on 4.IV.2024 in (A–B), 18.IV.2024 in (C).