Formosargus trivittatus Fachin & Hauser 2022, sp. nov.
Creators: name: Fachin, Diego Aguilar
name: Hauser, Martin
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Diptera
Stratiomyidae
Formosargus
Formosargus trivittatus

description: Formosargus trivittatus sp. nov.
(Figures 2 (c), 4(d–e), 6(d–e), 7(h), 10(c–e), 13, 16(b), 17(k–l), 20(b–d))
Diagnosis
Scutum with three well-marked dark brown bands (Figure 7 (h)); medial band narrowing at level of transverse suture, not discontinued as in F. variegatus, with median macula triangular on posterior part of scutum; end of posterior lateral bands weakly or not connected to medial macula; as in F. variegatus, scutellum yellowish, at most dark brown at extreme base; anterior lateral band extending widely over anepisternum, laterotergite at centre and mediotergite dark brown. Male abdominal tergites irregularly marked with dark brown, tergite 1 with a transverse dark brown band medially, tergite 3 faintly dark brown at centre, and tergites 4–5 with a pair of subrectangular dark brown spots (Figure 20 (b)); in females, transverse dark brown bands over all tergites, spots medially discontinued on tergites 2–3 and 5 (Figure 20 (d)).
Material examined
HOLOTYPE, 1 ♂ (left antenna slide-mounted; genitalia dissected and stored in microvial with glycerine), MALAYSIA, Malay Penins, Pahang, F.M.S., Fraser’s Hill, 4200 ft. [feet], 22 May 1932 (NHMUK). PARATYPE, 1 ♀ (genitalia dissected and stored in microvial with glycerine), THAILAND, Trang, Khao Pu-Khao Ya NP [National Park], -7.550633°S 99.789483°E, 75 m, Malaise trap 20–23 January 2006, M. Sharkey leg. T1958 (LACM).
Description
Male. Length (n = 1): body, 6.0 mm; wing, 6.0 mm. Head (Figures 4 (d), 6(d)). Vertex area as long as ocellar tubercle. Upper frons almost twice wider than long, twice shorter than lower frons; upper frons black lateral area nearly as broad as ocellar tubercle width, short yellowish pilosity; anterior margin of upper frons mostly straight, with a median triangular projection weakly pointing towards antennal insertion. Fourth flagellomere dark brown, subtriangular, as wide as previous flagellomeres combined (Figure 2 (c)). Face almost three times shorter than lower frons. Thorax (Figure 7 (h)). Three longitudinal dark brown bands over scutum; medial band wider, not completely interrupted at level of transverse suture, expanding posteriorly into a triangular macula; anterior lateral band wide, extending over notopleuron and anepisternum; each posterior lateral band with its apical end connected to median posterior triangular macula; laterotergite at centre and mediotergite dark brown. Legs with basal half of hind tibia and all three last tarsomeres brown, second hind tarsomere white; mid leg with a small, pointed structure at base of first tarsomere. Wing. R2+3 originating slightly beyond r–m, weakly sinuous towards wing margin. Abdomen. Reddish yellow; tergite 1 with a dark brown transverse band medially; tergite 3 with a pair of diffuse dark brown markings medially; tergites 4–5 with a pair of subrectangular dark brown markings. Terminalia (Figures 10 (c–e), 13). Outer margin of genitalia slightly prominent; ventral margin of genitalia with a median subrectangular projection; synsternite with a pair of short inner projections basally connected to the subrectangular projection, gradually narrowing towards apex, with regular setae on last third. Median lobes of phallus wider distally; parameral sheath shorter than gonostylus, roughly elliptical. Gonostylus roughly concave, wide in lateral view, with distal half much wider than basal half, dorsal margins projected upwards.
Female. Similar to male, except as follows: Length (n = 1): body, 5.5–9.0 mm; wing, 5.5– 8.0 mm. Head (Figures 4 (e), 6(e)). Upper frons as long as lower frons. Fourth flagellomere yellowish. Thorax. Posterior lateral scutal bands not connected laterally to median posterior triangular macula. Abdomen. All abdominal tergites with transverse dark brown spots; tergite 1 with a band on proximal half; spots on tergites 2–3, 5 not connected medially; short darkish pilosity over dark markings. Terminalia (Figures 16 (b), 17(k–l)). Genital fork wider at distal one-third, gradually narrowing towards a relatively wide, straight and rounded anterior end; posterior bridge nearly straight; posterolateral process curved on basal one-third, parallel on distal two-thirds, slightly pointing on last third; genital opening oval.
Etymology
The specific epithet is masculine and comes from the Latin word tri, meaning three, and vittae, for stripe or band, in reference to the three well-marked horizontal bands over the scutum of this species.
Geographic distribution
Oriental Region. Malaysia (Pahang), Thailand (Trang) (Figure 26).
Comments
Formosargus trivittatus sp. nov. is the only species of the genus reported from the continental portion of Southeast Asia, with one record from Malaysia (male) and one from Thailand (female). All the other species in the area have been found on islands (Taiwan and in the insular area of Southeast Asia).
description: Published as part of 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, pp. 1513-1562 in Journal of Natural History 56 (37 - 40) on pages 1555-1556, DOI: 10.1080/00222933.2022.2117107, http://zenodo.org/record/7318178