Anthomyza robusta, Roháček, 2020

Roháček, Jindřich, 2020, Anthomyzidae (Diptera) of Taiwan: new species but no new records, Acta Entomologica Musei Nationalis Pragae 60 (1), pp. 269-290 : 273-278

Anthomyza robusta sp. nov.

( Figs 1, 4 ¯21)

Type material. HƟĿƟŦYPൾ:, labelled: “ TAIWAN, Ali-shan [= Alishan], May 25, 1971, K. Kanmiya leg.” (handwritten) and “ Holotypus, Anthomyza robusta sp. n., J. Roháček det. 2019” (red label, printed). The specimen is intact, dry mounted on a pinned triangular card ( SMOC). PARAŦYPൾඌ: 1 10 ♀♀, with same label data as for the holotype, only second (type) label is yellow with “ Paratypus ” ( SMOC, 1 1 ♀ genit. prep.). Other paratypes: TAIWAN: [Chiayi County]: Mt. Alishan [= Alishan], 26.v.1971, 2 3 ♀♀ (1 genit. prep.); same locality, 2200 m, 1.xi.1985, 1, all K. Kanmiya leg. ( SMOC); Chiayi Hsien [= Chiayi County]:Alishan, 2300 m, 8.iv.1965, 3 3 ♀♀ (1 1 ♀ genit.prep., 1 with wing removed and preserved with genit. prep.), 9.iv.1965, 2 1 ♀, all T.Saigusa leg.( SIINH);Alishan Shamno (mountains), end of road from Chiayi, 23,28 N 120,48 E [= 23°28ʹ N 120°48ʹ E], 2000 m, pasture near park, surrounded by wood, swept, eclector, 11.iii.1994 (No. X 941), 1, Kung-ju Lin leg. ( ZSMC, dried from ethanol); Nantou Hsien [= Nantou County]: Tungpu [= Donpu], Lulinshan, 10.iv.1965, 1, T. Saigusa leg. ( SIINH); Nantou [County]: Nanhuashan, sweeping net, 6.v.1992, 2

4 ♀♀, Yang & Huang leg. ( NMNS, 1 genit. prep.); Nantou [County]: Meifeng, sweeping net, 27.ii.1992, 1, Y. C. Shiau leg. ( NMNS); Nantou [County]:Yunahaipaohsienso [24.046602 N, 121.236046 E], sweeping net, 4.v.1992, 1, W. T. Yang leg. ( NMNS); Nantou [County]: Kahoerhshan, sweeping net, 7.v.1992, 1 1 ♀, W.T.Yang leg. ( NMNS, 1 ♀ genit.prep.); Nantou County: Ren’ai Township, 3 km S of Lishan, Fushoushan,camping site, 24°13ʹ15ʺN 121°14ʹ20ʺE, 2560 m, sweeping vegetation, 12.v.2018, 2 2 ♀♀, M. Tkoč leg. ( NMPC, NMNS, 1 genit. prep.); Nantou County: Hohuachi, Lishan-Tayuling, road no. 8, 24°13ʹN 121°16ʹE, 1950 m, 31.iii.2000, 1 ♀, L. Peregovits & A. Kun leg. ( HNHM).

Description. Male. Total body length 2.30–2.58 mm; general colour dark brown, densely grey microtomentose, dull ( Fig. 4 ).

Head about as long as high, with indistinctly projecting frons and somewhat receding face but rounded anteriorly in profile. Occiput dorsomedially concave, blackish brown, medially with a pair of silvery whitish-grey microtomentose stripes (cf. Fig. 5 ) coalescing dorsally (sometimes also ventrally) and reaching from ocellar triangle to foramen. Frons darker than in A. trifurca , dark yellow or orange only in anterior fourth (lightest on orbits), frontal (including ocellar) triangle dark brown to brown (only anterior corner) and pale-grey microtomentose; stripes between frontal triangle and orbits brown to (anteriorly) pale brown, distinctly dark striated and often reaching as far as anterior margin of frons (cf. Fig. 5 ). Orbits dark yellow only anteriorly (up to anterior long ors) and becoming darker (brown) posteriorly, sparsely whitish microtomentose up to posterior ors, grey microtomentose beyond it. Frontal triangle large and broad, with acute anterior corner reaching to anterior fifth or sixth of frons. Frontal lunule distinct, yellow. Face narrow, weakly sclerotized medially and narrowly depressed, dull yellow and whitish microtomentose; parafacialia and gena pale yellow and silvery-white microtomentose, both bordered by broad ochreous to pale-brown marginal stripe; postgena dark brown, narrowly yellow ventrally, whitish-grey microtomentose; mouthparts dark ochreous except for yellow palpus. Cephalic chaetotaxy as in A. trifurca : pvt relatively long and strongly crossed; vti and oc subequal, longest of cephalic setae; vte and posterior ors slightly shorter than vti; 2 long ors, anterior somewhat shorter than posterior; 1 microsetula (only as long as medial microsetulae) in front of anterior ors; 1 pair (rarely 2 pairs) of medial microsetulae near anterior margin of frons; 1 proclinate setula behind vte distinctly longer than uppermost postocular; 6 or 7 postocular setulae, in single row; postgena with small setulae, and 1 or 2 relatively short posteroventral setae; 1 vi, about as long as anterior ors; subvibrissa reduced, weak, slightly longer than very fine and sparse (3–4) peristomal setulae. Palpus elongate, yellow, with 1 dark preapical seta and 3 ventral setulae. Eye large, broadly ovoid, narrower posterodorsally, with longest diameter slightly oblique and about 1.2–1.3 times as long as shortest. Shortest genal height about 0.14–0.16 times as long as shortest eye diameter. Antenna with orange-ochreous scape and pedicel; 1st flagellomere whitish yellow, but ochreous-brown around insertion of arista, with short, white pilosity on anteroventral margin. Arista dark brown, 1.9–2.0 times as long as antenna, with distinctly thickened basal segment and short, dark ciliation.

Thorax very slightly narrower than head, brown to blackish brown, dull due to dense pale-grey microtomentum ( Figs 4, 5 ), often with a bluish tinge; apical margin of scutellum, postalar callus and sutures between pleural sclerites usually paler brown. Thoracic chaetotaxy: 1 hu, longer than posterior npl; 2 npl (anterior longer); 1 prs (relatively long, as long as hu); 1 sa (as long as prs); 1 longer pa; 2 long postsutural dc (anterior shorter than posterior) and 6–7 dc microsetae in front of them; 4 rows of ac microsetae at level of suture but only 2 medial rows more posteriorly, these reaching (usually as single setula) to the level of posterior dc; 2 sc, laterobasal very weak, shorter than sa, apical as long as posterior dc (longest thoracic setae); 1 small but distinct, upcurved ppl; 2 stpl, anterior somewhat shorter, 2 or 3 setulae below the latter; ventral part of sternopleuron with 3 or 4 longer, paler setae. Scutellum rounded triangular, flat dorsally. Legs light yellow, only distal half of last tarsal segment of all tarsi brownish. f1 with ctenidial spine only slightly shorter than maximum width of t1, longer than that of A. trifurca ; f2 with posteroventral row of sparse, fine but long, erect setae; f3 with posteroventral row of setae but only a few (2–4) in apical third, thickened and shortened; t2 with short (although longer than maximum width of t2) ventroapical seta; t1, t3 and all tarsi simply setulose but fore and hind basitarsus with 2 or 3 ventral proximal setulae prolonged, less so on hind basitarsus. Wing ( Fig. 1 ) long but not very narrow, with pale-brown veins and pale-brown hyaline membrane. C with sparse and short spinulae between apices of R1 and R2+3. R2+3 long, bent parallel to C, with apex very slightly upcurving; R4+5 very slightly bent to straight, subparallel to M apically. Cell dm with r-m situated slightly in front of its middle. Apical portion of CuA1 slightly longer than dm-cu but not reaching wing margin; A1 short, ending far from margin. Alula small, well developed. Wing measurements: length 2.54–2.94 mm, width 0.85–0.97 mm, Cs3: Cs4 = 0.90–1.17, r-m\dm-cu: dm-cu = 2.20–2.62. Haltere with yellow stem and pale brown knob.

Abdomen. Preabdominal terga brown to blackish brown, with sparse grey or greyish-brown microtomentum, subshining. T1 shorter and narrower than T2, fused together only laterally; T2–T5 subequal in length, broad, each with sparse but relatively strong setae. Preabdominal sterna pale brown, with sparse fine setae, narrow anteriorly but becoming markedly wider posteriorly; S2 and S3 longer than wide, S4 slightly wider than long. S5 largest preabdominal sternum, much wider than long, transversely crescent-shaped, with strongly concave posterior margin. T6 short, transverse, membranous and entirely unpigmented. Synsternum S6–S8 dark brown, situated left laterodorsally, strongly asymmetrical and strikingly bulging on left side due to unusually convex S7. S6 larger than usual, as long as S7, with thick, strongly sclerotized and sinuous anterior ledge projecting onto ventral side and dorsally fused with that of S7. S6 with 2, S7 with 2–4 short setae. S8 longer than S7, longest on its right side and sparsely setose in posterior half.

Genitalia. Epandrium ( Figs 6, 7 ) of moderate size, slightly broader than high, with rather sparse setae including 2 pairs of longer setae; anal fissure small, subtriangular, more acute dorsally than in A. trifurca . Cercus relatively short and narrow, finely micropubescent and setose, with apical and preapical setae longest. Medandrium ( Fig. 6 ) of moderate size, subquadrate, ventrally as broad as dorsally, with dorsolateral corners more projecting than that of A. trifurca . Gonostylus ( Figs 6, 7, 10 ) most closely resembling that of A. trifurca but broader, with posterior marginal outline distinctly convex and with posteroventral corner blunter; micropubescent on almost entire outer side and setose on inner side. Hypandrium ( Fig. 11 ) relatively robust and broad (in dorsal view), with leaf-like anterior internal lobes ( Fig. 11 , hl) but differing from that of A. trifurca by the more expanded, fan-like anterior marginal part. Transandrium ( Fig. 12 ) closely resembling that of A. trifurca but with distinct, short and broad caudal process coalescing ventrally with basal membrane. Pregonites distinctly asymmetrical: left pregonite ( Fig. 11 ) with two large, ventrally protruding lobes; anterior lobe triangular (not rounded, lobate as in A. trifurca ) with 3 medial setae, and posterior lobe subequally long, also triangular but more acute, usually with 6 setae on anterior margin; in contrast, right pregonite with posterior lobe low, projecting little ventrally. Postgonite ( Fig. 11 ) relatively short but somewhat larger than in A. trifurca and slightly sinuate, with apex rounded and 1 anterior setula situated in the middle of anterior margin. Basal membrane densely, almost regularly spinose, but spinose area not as broad as in A. trifurca ( Figs 11, 12 ). Aedeagal part of folding apparatus with pale wart- like excrescences and 2 robust dark spines on left side ( Fig. 9 ) but with more pigmented spines (4 or 5 large and others shorter and paler) and a series of subterminal short dark blunt spines or tubercles on right side (see Fig. 8 ). Connecting sclerite membranous, hardly visible, not illustrated in Fig. 14 . Phallapodeme robust including fulcrum, basally asymmetrical as in A. trifurca , with apex tricuspid ( Fig. 14 ), with middle part somewhat projecting, in addition to lateral, wing-like projections. Aedeagus with small, short phallophore ( Fig. 14 ) having ventral claw-like sclerite as in A. trifurca . Distiphallus huge, broad including basally where fused with phallophore. Saccus short, smaller than in A. trifurca , largely overgrown by short unpigmented spines. Filum extremely robust and formed by single complex sclerite as in A. trifurca but markedly wider in middle and terminating in only 2 peculiar projections: 1 very long, slender, curved and pointed (formed by fusion of two very slender processes), directed posteriorly and bearing 1 distinct spine (only visible in ventral view, Fig. 13 ) and 1 shorter, blade-shaped and directed posteroventrally (see Fig. 14 ). Ejacapodeme very slender, similar to that of A. trifurca , also partly hidden in phallapodemal fork ( Fig. 14 ).

Female ( Fig. 5 ). Similar to male unless mentioned otherwise. Total body length 2.58–3.14 mm.Antenna with 1st flagellomere pale brownish on both outer and inner sides, yellow only along proximal and ventral margin. f2 and f3 simply setulose, with setae in posteroventral rows shorter, not erect or thickened. Last segments of all tarsi usually entirely brownish. Wing measurements: length 3.05–3.61 mm, width 0.99–1.23 mm, Cs3: Cs4 = 0.90–1.12, r-m\dm-cu: dm-cu = 1.91–2.50. Abdomen wider, with T1–T5 more transverse than in male. Preabdominal sterna narrow (pleural membranous part of segments large), pale ochreous, only S1 (short and transverse) and S2 brown; S3 and S4 somewhat longer than wide, becoming wider posteriorly; S5 distinctly wider than long, trapezoidal, posteriorly widened.

Postabdomen ( Figs 15–17 ) somewhat longer and more tapered from 7th segment than in A. trifurca . T6 large and long, almost as broad as T5, dark brown but with unique pale-pigmented, transverse and bare medial area in posterior fourth ( Fig. 16 ). S6 larger and wider than S5, transversely subtrapezoidal, wider posteriorly, pale ochreous ( Fig. 17 ). Tergosternum T7+S7 also different from that of A. trifurca , dorsomedial length shortest, but uniformly blackish brown both dorsally and laterally ( Figs 15, 16 ); ventral part ( Fig. 17 ) also dark, paler-brown pigmented only narrowly anteriorly (around medial basal sensilla, out to spiracles) and with longer micropubescence in anterior two thirds, setose in posterior half. 8th segment ( Fig. 15 ) largely membranous and densely micropubescent. T8 longer and narrower than in A. trifurca , with brown pigmentation tapered anteriorly, and lacking defined anterior margin, i.e. not separated from intersegmental membrane. S8 much shorter (although somewhat longer that that of A. trifurca ) than T8, divided medially into 2 brown-pigmented sclerites each posteriorly bent dorsally. Genital chamber with complex and asymmetrical internal sclerites ( Figs 19, 21 , is) closely resembling those of A. trifurca , but 2 pairs of partly fused and crooked posterior sclerites longer, without ventral extension ( Fig. 19 ) and medial annular sclerite slen- der, longer and anteriorly wider than in A. trifurca , located mostly anterior to the paired sclerites ( Figs 19, 21 ). Ventral receptacle ( Figs 19, 21 ) long, tube-like, hyaline, spirally coiled distally; its duct proximally slender but widened in the middle, thus very similar to that of A. trifurca ; remnants of accessory gland not observed (presumably very small as in other members of the A. bellatrix group, cf. RƟIJǍěൾĸ 2006). Spermathecae (1+1) subspherical ( Figs 18, 20 ), with distinct but relatively short terminal invagination, plain surface (without transverse striae), dark tuberculi- form spines surrounding duct insertion and small, partly pale-brown pigmented cervix. T10 small, narrow and short, dark-pigmented ( Fig. 16 ), with single medial pair of long setae and reduced micropubescence. S10 ( Fig. 17 ) narrow but longer than T10, brown, finely micropubescent and setulose as in A. trifurca . Cercus long and slender ( Figs 15, 16 ), with apical and dorsopreapical setae as long as cercus, closely resembling that of A. trifurca .

Discussion. Anthomyza robusta sp. nov. belongs to the A. bellatrix group (as defined by RƟIJǍěൾĸ 2006: 171) consisting of only E. Asian taxa. The phylogenetic relationships of this distinctive group of Anthomyza has hitherto not been unambiguously resolved (cf. RƟIJǍěൾĸ & BARƂൾR 2016, RƟIJǍěൾĸ et al. 2019) but it could be allied to some species described recently from China (RƟIJǍěൾĸ 2018). Nevertheless, this new Taiwanese species is clearly the closest relative of the E. Palaearctic A. trifurca which is also known from adjacent mainland China (RƟIJǍěൾĸ 2018). The next most closely allied species is the E. Palaearctic A. bellatrix Roháček, 1984 , which thus represents the sister species to this pair (cf. RƟIJǍěൾĸ & BARƂൾR 2016: 379, fig. 605). The sister-species relationship of A. robusta sp. nov. and A. trifurca is demonstrated by a number of synapomorphies, particularly in the male terminalia (phallophore with ventral claw-like sclerite; pregonites deeply bilobed and asymmetrical; saccus reduced but spinose; filum huge, broad also in proximal half and with long terminal projections). The two species also resemble each other externally including the form of the head, colouration of the frons, chaetotaxies and wing venation.

Anthomyza robusta sp. nov. can be confidently distinguished from A. trifurca by the following features: more robust body; distinctly darker frons (yellow restricted to anterior fourth of frons, dark stripes almost reaching anterior margin of frons); f1 with ctenidial spine longer; male f3 with only a few (2–4) thickened setae in apical third of posteroventral row; male S5 transversely crescent-shaped, with concave posterior margin; male synsternum S6–S8 strikingly bulging on left side due to unusually convex S7; gonostylus broader, with posterior outline distinctly convex and with posteroventral corner blunt; anterior lobe of left pregonite subtriangular; saccus small and largely covered by short unpigmented spines; filum much broader in the middle and its apex with only 2 main projections (the longer bearing a spine); female T6 with distinctive posterior transverse, bare and pale medial area; female T7+S7 entirely blackish brown dorsally; T8 elongate, narrower, brown but with pigmentation tapered anteriorly; all internal sclerites of female genital chamber longer; spermathecae (1+1) subspherical, with plain surface but with some tuberculiform spines. For further differences see above description.

Etymology. The name (robustus = robust, strong, Latin adjective) of this new species reflects the fact that it has a more robust body and male postabdomen than its closest relative, A. trifurca .

Biology. The biological data obtained from the type material are very limited, comprising only phenological and altitude information. However, thanks to M. Tkoč who collected the most recent series of specimens of A. robusta sp. nov. in Fushoushan (Nantou County), we know that the species is here associated with tussocks of the large grass Miscanthus sinensis Andersson (identified by D. Zelený) on the margins of montane forest (see Figs 2, 3 ). According to D. Zelený (personal communication, 2019), this grass is widespread in Taiwan, occurring from lowlands to high mountains, not only in natural but also in secondary successional or disturbed habitats. Considering this fact, it is interesting that A. robusta has so far been found only at high altitudes (1950–2560 m). Adults were collected by sweeping vegetation in February to May (most specimens in May), and November.

Distribution. Taiwan: Chiayi and Nantou Counties.

Figures

Figs 1–5. Anthomyza robusta sp. nov. and its habitat in Taiwan. 1 – wing, male paratype (length ca. 2.7 mm); 2 – grasses at margin of montane forest in Fushoushan (Nantou County), habitat of the species; 3 – detail with a tussock of grass, Miscanthus sinensis, probable host plant; 4 – male paratype from Alishan Mt., laterally (Chiayi County), body length ca. 2.5 mm; 5 – female paratype from the same locality, laterally, body length ca. 3.1 mm. Photos by M. Tkoč (2, 3) and J. Roháček (others).

Figs 6–14. Anthomyza robusta sp. nov., male paratype. 6 – external genitalia, caudally; 7 – the same, laterally; 8 – right wall of aedeagal part of folding apparatus; 9 – left wall of the same; 10 – gonostylus, lateroventrocaudally (widest extension); 11 – hypandrial complex, laterally; 12 – transandrium, caudally; 13 – filum of distiphallus, ventrally; 14 – aedeagal complex, laterally. All scales = 0.1 mm. For abbreviations see pp. 270–271.

Figs 15–21.Anthomyza robusta sp.nov., female paratype.15 – postabdomen, laterally; 16 – the same, dorsally; 17 – the same, ventrally; 18 – spermatheca; 19 – genital chamber with 8th abdominal segment, laterally; 20 – spermatheca; 21 – genital chamber, ventrally. Scales = 0.2 mm (Figs 15–17), 0.03 mm (Figs 18, 20) and 0.1 mm (others). For abbreviations see pp. 270–271.