Holotype. ♂ (RMBR), Vietnam, Lào Cai Province, Sa Pa Valley. Collected from dung on cow farm, 4km NE of Sa Pa town [22°21'28.19"N; 103°51'53.35"E, elevation 1250m ASL]. Collected 15.VII.2010 (Ang Y). Paratypes. 2 ♂ (RMBR), Indonesia, West Sumatra, Bukit Tingei Regency, Tanjung Mutiara Dist., Bantar Gadang Beach, [0°24.792"S; 99°56.307"E 0m ASL]. Collected 6.VII.2007 (Lohman D). ♂ (RMBR), Indonesia, N. Sulawesi, Tondano Province, Kampung Jawa [1°17'18.11"N, 124°52'30.05"E, elevation 650m ASL]. Collected 12.V.2009 (Ang Y).
The specific epithet old English for “spur” , and refers to the distinct spur-like medioventral tubercle found on the male fore femur.
Adult males of Sepsis spura closely resemble Sepsis nitens but can be distinguished by the following characters: (1) Medioventral tubercle on male fore femur of Sepsis spura is spur-like and bent at a forward angle with two smaller adjacent spines dorsally positioned at the end of the tubercle and one larger spine at the ventral end (Figs 24, 26), while the tubercle in Sepsis nitens is thicker on the base and has its three spines positioned more in a anterio-posterior fashion (Fig. 21). (2) The basal lamina-like projection on the fore tibia of Sepsis spura (Figs 25, 27) merges back with the tibia gently, but ends off with a distinct lobe in Sepsis nitens (Fig. 22). The short spines found posteriorly on the projection are also much weaker than those found in Sepsis nitens . (3) Sepsis spura (Figs 25, 27) has only one anterior lamina-like protrusion on the distal portion of the fore tibia, while Sepsis nitens (Fig. 22) has such protrusions on both anterior and posterior sides. (4) The surstylus of Sepsis nitens (Fig. 23) has a rather angular basal swelling and is relatively straight, curved only at the terminus, while the surstyli of Sepsis spura (Figs 30, 31) has a rounded basal swelling and is medially curved for the entirety of the surstylus. Sepsis spura can be distinguished from other Sepsis , also based on the specific structure of the male fore leg ornamentation and the shape of the surstylus.
Colour. Head capsule mostly brown with a thin light brown strip on gena; fascial margin black. Vertex dark brown. Facial carina and lunule light grey-brown. Pedicel dark brown, 1st flagellomere yellowish, arista brown. Proboscis whitish yellow. Forelegs wholly yellow. Mid and rear coxa yellow with brown base. Mid femur brown but yellow on basal and distal tips; mid tibia brown on basal half and diffuses to yellow on apical half. Rear femur yellow but brown on dorsal region, while rear tibia wholly brown. Fore tarsus with tarsomeres 3-5 brown, mid tarsus with tarsomeres 3-5 very lightly brown, rear tarsus with tarsomeres 4 and 5 brown. Wing clear except for basicostal cell and basal region of costal cell, which is light brown. Veins dark brown. Calypter clear, margin and fringe-hairs yellowish. Haltere white. Thorax mostly dark brown, but pronotopleuron is yellow. Abdominal tergites and sternites glossy dark brown.
Head. Roundish, facial carina short and shallow, facial area receding. Gena and parafacial region narrow. Largely glossy except for lightly microtomentose occipital region. Chaetotaxy: 1 ocellar, 1 divergent postocellar (ocellar longer than postocellar), 1 inner vertical, 1 outer vertical (outer subequal to inner). Orbital very reduced to absent. 3-4 vibrissae. 3-4 postocular. Lower fascial margin lined with setulae.
Thorax. Scutum, postpronotum and scutellum wholly microtomentose. Subscutellum microtomentose with a small glossy spot ventromedially. Mediotergite microtomentose on margins and glossy in the medial region. Scutellum twice wide as long. Pleural pruinosity pattern (Fig. 28): Proepisternum lightly microtomentose. Anepisternum largely glossy with a small strip on the anterioventral and posteriodorsal margins very lightly dusted. Balsare glossy. Katepisternum densely microtomentose.Anepimeron glossy. Katatergite, meron and metepimeron microtomentose. Chaetotaxy: 1 apical scutellar, 1 reduced basal scutellar, 1 row dorsocentral with posterior-most two setae as bristles, 1 row acrostichial and 1 postalar, 1 supraalar, 1 notopleural, 1 postpronotal, 1 anepisternal and 2 posterior spiracular.
Legs. Forelegs modified; fore femur (Figs 24, 26) with large submedian ventral spine and robust, forward curving spur-like protrusion at the median. This protrusion terminates with three short stout spines, with two adjacently positioned dorsally and one positioned ventrally. Fore tibia (Figs 25, 27) with a submedial and medial cuticular laminar extension; submedial extension with row of short spines. Additional chaetotaxy: Fore tibia with apical anteriodorsal. Mid femur with 1 anterior. Mid tibia with 2 posterior on median and subapex, 2 dorsal on basal 2/3 and apex, 1 anterior on apex, 1 anterioventral on basal 2/3 and 1 ventral on apex. Hind femur with 1 anteriodorsal on basal 2/3 and 1 posterioventral subapically. Hind tibia with 2 dorsal at median and subapically, 1 anterior at median and 2 anterioventral medially and subapically. Rear basitarsus with 2 ventral dark spines basally.
Wings. Without pterostigma. Veins bare. Covered with microtrichiae except for basal half of basal-medial cell. Anterior region of r2+3 cell with sparse microtrichiae. Radial-medial cross-vein divides discal-medial cell by ratio of slightly less than 2: 1. Length: 2.9-3.5mm.
Abdomen. Tergites glossy black, syntergite 1+2 - tergite 5 normal, tergite 6 missing, syntergite 7+8 present and extending ventrad as a narrow sclerite. Spiracles 1-3 on intersegmental membrane close to tergite, spiracles 4 and 5 within respective tergites near margin. Spiracles 7 and 8 adjacent on margin of syntergite 7+8. Sternite 1 a broad rectangle with posterior invaginations while sternite 2 is triangular, tapering posteriorly; sternite 3 is oblong. Sternite 4 is V-shaped with setae and one stout discal bristle on each lateral margin; sternite 5 reduced to a thin lateral crescent (Fig. 29).
Hypopygium. Cercal plate with two very weak lobes, each with single distal setae. Hypopygium and surstylus relatively setaeless. Surstylus fused to hypopygium; bulging medially at base but thin and curved medially, slightly dentate terminally (Figs 30, 31).
Indonesia (Sulawesi, Sumatra), Vietnam ( Lào Cai).
Key to species of the genus Perochaeta Duda, 1926 (males)
1 Ratio of radial-medial cross-vein dividing discal-medial cell is 1:1 2 - 1:2 to 1:3 3 2 Surstylus without large medial protrusions; with small dentate terminus Perochaeta orientalis Duda, 1926 - Sternite brush embedded in membrane 4 3 Sternite brush as a free sclerotized lobe 5 - Sternite brush with few bristles (ca. 5 short and 5 long bristles); surstylus with large, squat triangular protrusion on inward median Perochaeta hennigi Ozerov, 19924 Surstylus without any large medial protrusions 6 - Surstylus with large medial protrusions 7 5 Sternite brush with few bristles (ca. 5 short bristles and 5 long bristles); surstylus without large median protrusions Perochaeta dikowi Ang et al., 2008 - Medial protrusion emerges dorsally on surstylus; posterior margin of 4th sternite V-shaped with many bristles Perochaeta cuirassa Ang, 2010 6 Medial protrusion emerges ventrally on surstylus; posterior margin of 4th sternite as two distinct lobes with many bristles Perochaeta lobo Ang, 2010