Protracheoniscus flavus Jiang and Li, sp. n.

http://zoobank.org:act: 0E7EA7AF-C1DE-4A4D-AEB8-E26F025D9153

(Figures 1 (A), 2, 3, 4)

Type species

Protracheoniscus politus (Koch, 1840).

Material examined

Holotype. 1 male, CHINA: Sichuan Province, Aba Tibetan and Qiang Autonomous Prefecture, Songpan County, Zhenjiangguan Town (32.3279°N, 103.7221°E), 2,720 m, 4 March 2023, leg. Chao Jiang, no. 20230804201. Paratypes: 2 males, 5 females, nos. 20230804202–20230804204, same data as holotype.

Diagnosis

Male pleopod 1 exopod apex deeply bilobed, outer lobe as long as inner one, twice as wide; endopod bearing a seta and several clumps at apex. Pereopod 1 bearing brush of long trifid setae on carpus and merus.

Description

Body oval, convex, black brown colour with pale yellow muscle spots on antero-lateral corners of pereonites (Figure 1 (A)). Dorsal surface smooth, with long and tricorn-shaped scale-setae (Figure 3 (B)). Noduli laterales on pereonites 1–4 farther from lateral margins than those on pereonites 5–7 (Figures 3 (A) and 4(G)). Cephalon with medial lobe slightly convex, lateral lobe well developed (Figure 3 (A)). Eye with 15–19 ommatidia. Antennula of 3 articles; bearing a tuft of aesthetascs at apex (Figure 4 (A)). Antenna with fifth article of peduncle longer than flagellum; flagellum with distal article as long as proximal one (Figure 3 (C)).

Pereonite 1 with round postero-lateral corner, pereonites 2–3 with postero-lateral corners nearly right-angled, pereonites 4–7 with acute postero-lateral corners and directed backwards (Figures 1 (A) and 3(A)). Pereopod 1 densely covered with trifid setae on sternal margin of carpus and merus (Figure 3 (D)). Pereopods 6–7 scattered with setae on sternal margin of merus and carpus (Figure 3 (E)).

Left mandible with molar process carrying 3 teeth and lacinia mobilis with 2 teeth; lobe covered by setae with 4 plumose penicils; pars molaris consisting of several plumose setae on a short common socket (Figure 4 (B)). Right mandible with molar process carrying 2 teeth and lacinia mobilis with straight edge; 10–15 penicils between lacinia mobilis and molar process; pars molaris consisting of several plumose setae on a short common socket (Figure 4 (C)). First maxilla with outer branch bearing 4 + 4 teeth; inner branch with 2 long penicils and a triangular posterior point (Figure 4 (E)). Second maxilla distally bilobate and setose, inner lobe wider than outer one (Figure 4 (D)); maxilliped endite rounded with 3 spurs, palp slender (Figure 4 (F)).

Pleopods 1–5 exopods with monospiracular internal lungs (Figure 3 (G–K)). Male pleopod 1 exopod apex deeply bilobed, outer lobe as long as inner one, twice as wide; endopodite with broad basal part, narrowed towards apical tip, bearing single seta and several clumps at apex (Figure 3 (G)). Pleopod 2 exopod nearly triangular, gently concave on outer margin; endopod longer than exopod, distal article thin, long (Figure 3 (H)). Pleopods 3–5 exopods bearing 1 line of setae on outer margin (Figure 3 (I–K)). Telson triangular, almost twice as wide as long, distal apex surpassing protopod; uropodal exopod approximately twice as long as protopod (Figure 3 (A)).

Size

Males 12–14 mm, females 12–15 mm.

Distribution

China (Sichuan).

Remarks

This new species is similar to Protracheoniscus ehsani Kashani, P. golestanicus Kashani and Hamidnia, and P. gakalicus Kashani, Malekhosseini and Sadeghi, in the arrangements of noduli laterales and the antennal flagellum with distal article as long as proximal one (Kashani et al. 2013, 2014, 2016). However, it can be distinguished by male pleopod 1 exopod deeply bilobed and endopod with several clumps at apex. In P. golestanicus, the male pleopod 1 exopod is gently bilobed and the apex of the endopod has a finger-like lobe bearing a row of a few small setae at the apex. In P. ehsani and P. gakalicus, the apex of male pleopod 1 exopod is uncracked and the endopod has a line of small setae at the apex.

Etymology

From the Latin flavus = yellow. The new species name refers to the antero-lateral corners of its pereonites with pale yellow muscle spots. We suggest the Chinese common name ‘黄斑原气管虫’.