Formosargus lineatus ( de Meijere, 1913 )

Fachin, Diego Aguilar & Hauser, Martin, 2022, Revision of Formosargus James, 1939 (Diptera: Stratiomyidae): five new species in an otherwise rare genus and Amsaria Adisoemarto, 1974 as a generic synonym, Journal of Natural History 56 (37 - 40), pp. 1513-1562 : 1534-1536

Formosargus lineatus ( de Meijere, 1913)

( Figures 2 (a, b), 3(b, c), 5(d, e), 7(c), 8(c–e), 9(a), 10(a, b), 11, 15(b), 17(c, d), 18 (b–e), 23)

Chrysochlora lineata de Meijere, 1913: 318 (orig. descr.).

Type locality: Indonesia, Irian Jaya, Alkmaar . Holotype: ♀ [ ZMAN] .

Refs: Brunetti, 1923: 158 (list); Lindner, 1957: 194 (suppl. descr. of male); Woodley, 1989: 316 (cat.); Woodley, 2001: 175 (cat.); Hauser et al., 2017b: 950 (com.); Lessard et al., 2020: 27 (comb. nov.), 28–29 (com.).

Diagnosis

Species very similar to F. kerteszi , but differs from it by pleuron completely yellowish in both sexes, without dark markings over anespisternum and mediotergite. Upper frons shortened as in other species, but roughly four times shorter than lower frons ( Figure 5 (d, e)). Scutal band clearly more homogeneous in width, only slightly wider about at level of transverse suture ( Figure 7 (c)), while in F. kerteszi , it is wider on posterior half ( Figure 7 (a)). Abdomen in males only with a pair of dark brown spots on tergite 1 ( Figure 18 (b)); completely yellowish in females as in F. kerteszi , while in F. melanogrammus , it has spots on tergites 2–5.

Material examined

Type material. HOLOTYPE ( Figure 23 (a–c)), 1 ♀, INDONESIA, Irian Jaya [West Papua Province], Alkmaar ( ZMAN).

Additional material. 1 ♂ (left antenna slide-mounted; genitalia dissected and stored in microvial with glycerine), INDONESIA, [West Papua Province] Neth . Ind.- American, New Guinea Exped . [Expedition], Araucaria Camp 800 m, [- 3.5°S 139.183333°E], 09 March 1939, L.J. Toxopeus ( RMNH) . 1 ♀, N. Dutch New Guinea [= Indonesia], Waigeu [West Papua Province, Waigeo], Camp . Nok., 2500 ft. [feet], April 1938, L.E. Cheesman, B.M. 1938–593 ( NHMUK). 2 ♀ (1 ♀ with left antenna and wing slide-mounted, genitalia dissected and stored in microvial with glycerine), PAPUA NEW GUINEA, Bulolo [Morobe Province], Rifle range LA, 23 February 1983, sp . no. 2014, Pandanus sp. , H.R. Roberts, C. IE A14858 ( NHMUK) . 1 ♀, Morobe Province, Tekadu, - 7.633333°S 146.566667°E, 09 February 2000, T . A Sear and Binatung, brigade MT ( UCD) .

Redescription

Male. Length (n = 1): body, 6.5 mm; wing, 6.0 mm. Head ( Figure 3 (b), 5(d)). Vertex area slightly longer than ocellar tubercle. Upper frons very reduced, twice wider than long, roughly four times shorter than lower frons; black lateral area of upper frons much narrower, short yellowish pilosity; anterior margin of upper frons inverse-U-shaped, pointing towards ocellar tubercle. Fourth flagellomere rounded, as wide as each previous flagellomere alone or slightly wider ( Figure 2 (a)). Face three times shorter than lower frons. Thorax ( Figure 7 (c)). Medial scutal band dark brown, homogeneous in width along extension, with a subtle enlarging at level of transverse suture; pleuron entirely yellow. Mid leg with a curled modified structure at apex of first tarsomere ( Figure 8 (c–e)); tarsomeres yellowish. Wing ( Figure 9 (a)). R2+3 originating slightly before r–m, weakly sinuous. Abdomen. Mostly yellowish in background, with a pair of subrectangular dark brown maculae on tergite 1. Terminalia ( Figures 10 (a, b), 11). Ventral margin of genitalia with a median bilobed and acuminate projection; synsternite with a pair of well-developed and long inner projections, curved at base, parallel on distal two-thirds, with strong bristles on last third, slightly exceeding distal margin of genitalia. Phallus exceeding gonocoxal bridge distally; parameral sheath as long as gonostylus, subrectangular. Gonostylus wide in lateral view, bilobed.

Female. Similar to male, except as follows: Length (n = 4): body, 5.5–9.0 mm; wing, 5.5– 8.0 mm. Head ( Figures 3 (c), 5(e)). Lower frons and face white. Thorax. Medial band narrower than in males ( Figure 18 (d)). Abdomen. Homogeneously yellow, without dark markings on tergites. Terminalia ( Figures 15 (b), 17(c, d)). Genital fork equally wide on distal two-thirds, lateral margins projected backwards; basal third abruptly narrowing into a very thin, roughly straight and pointed anterior end; posterior bridge bilobed; posterolateral nearly parallel, with basal two-thirds enlarged, gradually narrowing into a rounded apex.

Geographic distribution

Australian Region. Indonesia (West Papua), Papua New Guinea (Morobe) ( Figure 26 ).

Comments

Formosargus lineatus was originally described in Chrysochlora based on a female and only reported again by Lindner (1957) from a male from Indonesia (West Java) collected in 1939, which is here examined. The species was recently transferred to Formosargus ( Lessard et al. 2020, referred to as Formosargus lineata ), but images of the holotype are only now provided with the redescription of the species.

Figures

Figure 2. Antennae of Formosargus species. (a) F. lineatus, male. (b) F. lineatus, female. (c) F. trivittatus sp. nov., male, holotype. Abbreviations: ar t flgm, arista-like terminal flagellomere; flg, flagellum; ped, pedicel; scp, scape.

Figure 3. Heads of Formosargus species, dorsal view. (a) F. kerteszi, female. (b–c) F. lineatus (b. male; c. female). (d) F. sagittocerus, male.

Figure 5. Heads of Formosargus species, frontal view. (a–c) F. kerteszi (a. male, Philippines; b. female, Allotype [DEI], Taiwan; c. female, Philippines). (d–e) F. lineatus (d. male; e. female). (f) F. sagittocerus, male. Arrow: anterior margin of the upper frons at the edge with lower frons.

Figure 7. Thorax of Formosargus species, dorsal view. (a–b) F. kerteszi (a. male, holotype [DEI]; b. female, Philippines). (c) F. lineatus, male; arrow: medial band. (d) F. sagittocerus, male. (e) F. berezovskiyi sp. nov., female, paratype; arrow: mediotergite. (f) F. borneensis sp. nov., female, holotype; arrow: notopleural macula. (g) F. mangoleensis sp. nov., female, holotype; arrow: mediotergite. (h) F. trivittatus sp. nov., male, holotype; arrow: anterior lateral band. (i) F. woodleyi sp. nov., male, holotype.

Figure 8. Male mid legs of Formosargus species, male. (a–b) F. kerteszi. (c–e) F. lineatus. (f–h) F. sagittocerus. (i–j) F. woodleyi sp. nov., holotype. Arrow: modified structure at base of basitarsus. Abbreviations: fem, femur; tsm 1, first tarsomere.

Figure 9. Wings of Formosargus species. (a) F. lineatus, female. (b) F. berezovskiyi sp. nov., female, paratype. (c) F. woodleyi sp. nov., male, holotype. Abbreviations: A1, first branch of anal vein; al, alula; an lb, anal lobe; bm, basal medial cell; br, basal radial cell; C, costal vein; c, costal cell; Cu, cubital vein or cubitus; CuA, anterior branch of cubital vein; cua, anterior cubital cell; CuA+CuP, anterior branch of cubital vein and posterior branch of cubital vein; CuP, posterior branch of cubital vein; cup, posterior cubital cell; d, discal cell; h, humeral crossvein; M, medial vein or media; M1, first branch of media; m1, first medial cell; M1+2, fused first and second branch of media; M2, second branch of media; m2+3, fused second and third cell of media;M3, third branch of media; M3+4, fused third and fourth branch of media; M4, fourth branch of media; m4, fourth medial cell; m–cu, medial–cubital crossvein; m–m, medial crossvein; R1, anterior branch of radius; r1, first radial cell; R2+3, second branch of radius; r2+3, second and third radial cell; R4, upper branch of third branch of radius; r4, fourth radial cell; R5, lower branch of third branch of radius; r5, fifth radial cell; r–m, radial–medial crossvein; Rs, radial sector; Sc, subcostal vein sc, subcostal cell.

Figure 10. Male terminalia of Formosargus species (epandrium, proctiger, and cerci removed). (a–b) F. lineatus (a. dorsal view; b. lateral view). (c–e) F. trivittatus sp. nov., holotype (c. dorsal view; d. ventral view; e. lateral view). (f) F. woodleyi sp. nov., lateral view, holotype. Abbreviations: goncx apod, gonocoxal apodeme; goncx brg, gonocoxal bridge; gonst, gonostylus; ph, phallus; pm sh, parameral sheath. Scale bars: 0.1 mm.

Figure 15. Female terminalia of Formosargus species, dorsal view. (a) F. kerteszi. (b) F. lineatus. (c) F. berezovskiyi sp. nov., paratype. (d) F. borneensis sp. nov., holotype (cerci lost). Abbreviations: cerc, cercus; st, sternite; tg, tergite.

Figure 18. Habitus of Formosargus species. (a) F. kerteszi, female, dorsal. (b–e) F. lineatus (b–c. male, dorsal and lateral, respectively; d–e. female, dorsal and lateral, respectively). (f) F. sagittocerus, male, dorsal.

Figure 23. Chrysochlora lineata, female, holotype [ZMAN]. (a) Habitus, dorsal view. (b) Habitus, lateral view. (c) Habitus, frontal view.

Figure 26. Geographic distribution of Formosargus. Squares represent holotypes records; circles represent paratypes, and additional material. Three of the ‘lines’ of faunal division are shown: 1. Wallace’s Line; 2. Weber’s Line; 3. Lydekker’s Line. ‘Wallacea’ is the area that lies between Wallace’s Line and Lydekker’s Line.