Formosargus borneensis 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 borneensis

description: Formosargus borneensis sp. nov.
(Figures 4 (b), 6(b), 7(f), 15(d), 17(g–h), 19(d–e))
Diagnosis (female)
Species distinctly reddish in colour. Medial band on scutum slightly wider on posterior half (Figure 7 (f)), with a narrowing at level of the transverse suture and yellow one-third of scutum as wide as in F. berezovskiyi sp. nov., but differs from it by a pair of anterior lateral dark brown maculae over notopleuron (Figure 19 (d)). Abdominal tergites with subtle brownish markings, mostly conforming with the background colour (Figure 19 (e)).
Material examined
HOLOTYPE, 1 ♀ (genitalia dissected and stored in microvial with glycerine), MALAYSIA, B. [British] N. [Northern] Borneo, [Sabah], Mt. [Mount] Kinabalu, Kamborangah, 7000 ft. [feet], 18 April 1929, [coll. H. M. Pendlebury] (NHMUK).
Description
Female. Length (n = 1): body, 10.0 mm; wing, 9.0 mm. Head (Figures 4 (b), 6(b)). Vertex area twice longer than ocellar tubercle. Upper frons as wide as long, twice longer than lower frons; upper frons black lateral area broader than ocellar tubercle width, with short dark brownish pilosity; anterior margin of upper frons with a median triangular projection pointing towards antennal insertion. Fourth flagellomere rounded, as wide as each previous flagellomere alone or slightly wider. Face nearly as long as lower frons. Thorax (Figure 7 (f)). Medial scutal band dark brown, nearly as wide as one-third of scutum, with a subtle narrowing at level of transverse suture, wider posteriorly, weakly discontinued at base of scutellum; a subrectangular dark brown macula over notopleuron area, extending over anepisternum proximally; laterotergite reddish yellow, mediotergite with only a small dark brown mark. Basal half of hind femur dark brown. Wing. R2+3 arising slightly before r–m, weakly curved towards R1 on basal third, nearly straight on apical two-thirds. M1 and M3 less faint. Halter mostly reddish yellow, distal half of knob dark brown. Abdomen. Reddish, with a central transverse brownish band, nearly covering entire surface of each tergites 1–5 (Figure 19 (d)), conforming in colour with the background; pilosity reddish yellow. Terminalia (Figures 15 (d), 17(g–h)). Genital fork wider medially at level of posterolateral process insertion; anterior half subtriangular, narrowing into a relatively slender and rounded anterior end; posterior bridge weakly bilobed; posterolateral process enlarged and rounded at base, much slenderer on next one-third, enlarging on last third towards apex, distal half nearly parallel; genital opening reduced, roughly oval.
Male
Unknown.
Etymology
The specific epithet, borneensis, refers to the collection site of the holotype of the new species, the island of Borneo.
Geographic distribution
Oriental Region. Malaysia (Sabah) (Figure 26).
Comments
This species is part of a group of species, including F. kerteszi, F. lineatus, F. berezovskiyi sp. nov., F. mangoleensis sp. nov. and F. melanogrammus, that share the presence of a single medial dark brown band on the scutum (see Figure 7 (a–c, e, g)) and a rounded fourth flagellomere (see Figure 2 (a, b)). Formosargus borneensis sp. nov., however, has a pair of additional subrectangular dark markings laterally on the anterior part of the scutum, mostly over the notopleuron (Figure 19 (e); see couplets 1 and 2 in the key). This feature indeed has similarities to the condition seen in the three-striped species, for example to that of F. trivittatus sp. nov. (Figure 20 (c)). The difference is that in F. trivittatus sp. nov. and in the other species related to it, the lateral macula is not only over the notopleuron but also extends over the anterior part of the scutum (see Figure 7 (h)).
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 1552-1553, DOI: 10.1080/00222933.2022.2117107, http://zenodo.org/record/7318178