Perochaeta lobo Ang 2010

Ang, Yuchen & Meier, Rudolf, 2010, Five additions to the list of Sepsidae Diptera for Vietnam: Perochaeta cuirassa sp. n., Perochaeta lobo sp. n., Sepsis spura sp. n., Sepsis sepsi Ozerov, 2003 and Sepsis monostigma Thompson, 1869, ZooKeys 70, pp. 41-56 : 46-47

Perochaeta lobo Ang 2010 sp. n. Figs 6-9

Material.

Holotype. ♂ (RMBR), Vietnam, Lào Cai Province, Sa Pa Valley. Baited with cow dung at forest edge next to a small cascade alongside highway, ca. 850m along the road westward of the Thác bạc (Silver Waterfall) tourist attraction [22°23'23.90N; 103°44'50.32E, elevation 2600m above sea level, ASL]. Collected 16.VII.2010 (Ang Y).

Etymology.

The specific epithet is a phonetic translation of Greek “λοβό”, which refers to the large, distinct lobe found on each lateral half on the posterior margin of the 4th sternite.

Diagnosis.

The adult male is very similar to Perochaeta cuirassa and can only be reliably distinguished based on the 4th sternite and hypopygium. The 4th sternite [cf. Perochaeta lobo (Fig. 6) and Perochaeta cuirassa (Fig. 1)] can be distinguished to species by the presence of distinct lobes on the posterior end, the long, thin sternite brush (as opposed to short and squat in Perochaeta cuirassa ), and the sternite itself being narrower (half wide as long). The structure of the hypopygium (Figs 7-9) is also diagnostic given that it is the only Perochaeta with a surstylus that has a dorsal flap along its length and a long distal-pointing projection sub-basally. Other diagnostic characters that distinguish Perochaeta lobo from Perochaeta dikowi , Perochaeta hennigi and Perochaeta orientalis as described in diagnosis for Perochaeta cuirassa .

Description (male).

Colour. As described in Perochaeta cuirassa except for fore and rear basitarsi, which are brown with yellow base, mid basitarsus yellow with slight brown region apically.

Head. As described in Perochaeta cuirassa .

Thorax. As described in Perochaeta cuirassa ; pleural pruinosity patternas in Fig. 5.

Legs. Forelegs unmodified; as described in Perochaeta cuirassa .

Wings. Coloration, venation and microtrichia distribution as described in Perochaeta cuirassa . Length: 4.2 mm.

Abdomen. Tergites and sternites 1-3 as described in Perochaeta cuirassa . Sternite 4 heavily modified (Fig. 6); almost twice long as wide and raised from the abdomen. Posterior edge of 4th sternite deeply invaginated and raised to form two large distinct lobes densely populated with strong bristles, mainly lining the outer discal margin. Two long, thin moveable appendages (= sternite brushes) branch off laterally on the posterior end of the sclerite, each with large, thick bristles on the outer region and some shorter, thinner bristles closer to the inside. A Y-shaped apodeme extends underneath and anterior to the 4th sternite.

Hypopygium (Figs 7-9). Cercal plate with two very weak lobes; distal margin covered with numerous setae. Hypopygium triangucuspid projection before the base of the surstylus. Surstylus itself fused to hypopygium and branches off terminally, with a dorsal flap along its length and a longish distal-pointing projection sub-basally. Terminal section of surstylus shaped like a scapula, with distal-pointing cuticular “teeth” and setulae on distal margin, and a very small inward-facing “tooth” on both the ventral and dorsal region subterminally pointing towards the median.

Distribution.

Vietnam ( Lào Cai).