Malthinellus mushanus sp. nov.

(Figs. 2A–I, 7B, I, 8C, H, 10)

Malthinus crenulatus: Wittmer, 1984: 155 (part; misidentification).

Type material. Holotype, male (NMNS), “ Taiwan Nantou / Chunyang / IV/6–V/1/2004 / C. S. Lin & W. T. Yang / Malaise trap (KCN)”, “ NMNS ENT / 5249-2303 ”. Paratypes (8 males): 3 males (NMNS ENT5237-1817, 1839, 3223), same collecting data as the holotype but “ IV/9–V/7/2002 ”; 1 male (TARI), “ Taiwan: Nantou / Chientai trail (尖台ūã) / 12.III.2019. leg. W.-C. Liao ”; 2 males (EUMJ), “ 台=南üñ仁Ēae力n'āDzãw / 24.055°N, 121.155°E / [TAIWAN] Nantou Hsien, / Ren’ai Township, / Lixing Industry Road, / 7 May 2016, Yu HISASUE leg.”; 1 male (NHMB), “[TAIWAN] / Meifeng / Nantou Hsien ”, “ 26. VI. 1971 / Y. Miyatake ”; 1 male (NHMB), “ Nanzan-kei / Formosa / 29. III. 1967 / S. Fukuda ”.

Etymology. Named after the locality name “Musha (mữ)”. This is a traditional name by indigenous people and corresponds to Ren'ai Township, Nantou County, Taiwan. This new species has been collected only from this area.

Description. Male. BL 3.88–4.13 (4.13 in the holotype = HT) mm. Body dark blackish-brown; head, pronotum, scutellum, trochanters, and femora yellowish orange to orange (but the posterior part of head, median area of pronotum, and scutellum infuscate in one paratype from Meifeng); palpomeres and sternite IX dark brown; mandibles yellowish orange in basal halves, dark orange in apical halves; antennomere I yellowish orange, slightly darkened apically and antennomeres II–XI dark brown; tibiae and tarsi yellowish orange to brown, usually darkened towards the apices. Body densely covered with yellowish-white short pubescence.

Head rounded, HW 0.81–0.87 (0.86 in HT) mm, HW/PW 1.08–1.19 (1.19 in HT); eyes globular and moderately protruding, interocular distance 3.00–4.23 (3.38 in HT) times as wide as the diameter of an eye; antennae filiform, reaching basal 3/5 of elytra, comparative lengths of antennomeres as follows: 1.89: 1: 1.27: 1.46: 1.53: 1.52: 1.51: 1.39: 1.34: 1.35: 1.55.

Pronotum trapezoidal, sides slightly widened posteriorly, anterior angles rounded, lateral margins slightly sinuate near slightly produced or angulate hind angles, disc coarsely punctate, moderately convex but flattened in the median area; PL 0.54–0.61 (0.57 in HT) mm, PW 0.71–0.80 (0.73 in HT) mm, PW/PL 1.27–1.31 (1.28 in HT). Scutellum trapezoidal with rounded apex. Elytra moderately long, sides parallel, slightly narrowed and rounded at apex; EL 2.67–2.95 (2.88 in HT) mm, EW 1.03–1.08 (1.05 in HT) mm, EW/PW 1.34–1.51 (1.45 in HT), EL/EW 2.60–2.74 (2.73 in HT). Legs slender; femora mostly straight; tibiae feebly arcuate.

Sternite VIII (Fig. 8C) with apical margin deeply and broadly emarginate in a V-shape, the depth of the incision reaching approximately 3/4 of the length of the sternite, bottom of the incision smoothly rounded. Sternite IX (Fig. 8H) broadly oval, abruptly narrowed and curved dorsally at apical 1/6, apex slightly angulate or bilobate.

Aedeagus (Figs. 2E–I), 0.93–1.02 (1.02 in HT) mm in length; stout, subquadrate with rounded corners in dorsal and ventral outline; basal piece broadly rounded triangular in ventral outline, mostly covering the inner basal piece, with apical margin slightly emarginate, ventral surface with a medio-longitudinal furrow, gently convex medio-ventrally and weakly curved dorsally in profile; inner basal piece with broad anterior terminal, the left and right parts nearly fused, weakly elevated dorsally as a whole, appearing wedge-shaped in profile and projecting as quadrate plates in caudal view; outer lateral lobe divided into two parts: outer lateral lobe 1 robust, extending dorsally, then abruptly narrowed and strongly curved medially, with its apical part further elongated antero-posteriorly, apex rounded in profile and forming an elongate oval in dorsal view; outer lateral lobe 2 arising from the base of lobe 1, strongly digitiform, weakly curved posteriorly, apex acute in profile; inner lateral lobe flattened, elongate spoon-shaped, extending postero-medially with a gentle curve, apex broadly rounded; penis robust, divided into two lateral parts, each quadrate and projecting dorsally in profile; central part of centrophyse with a pair of rod-like processes medially, as long as penis, slightly undulate and slightly curved posteriorly.

Differential diagnosis. The three species occurring in Taiwan are externally very similar and share an elongate, spoon-shaped inner lateral lobe, but they are different in the following points. Dorsal coloration: posterior part of head, median area of pronotum, and scutellum are infuscate in Malthine. crenulatus, but entirely orange in Malthine. crenulatomimus, and both forms are present in Malthine. mushanus sp. nov.; sternite VIII: the V-shaped incision reaching approximately half the length of the sternite in Malthine. crenulatus and Malthine. crenulatomimus, while reaching approximately 3/4 of the length of the sternite in Malthine. mushanus sp. nov.; size of aedeagus: larger (more than 0.93 mm) in Malthine. mushanus sp. nov., smaller (less than 0.72 mm) in Malthine. crenulatomimus, and intermediate size in Malthine. crenulatus; basal piece of aedeagus: apical margin is protruding in quadrate-shape at the central 1/ 3 in Malthine. crenulatomimus, while not protruding and slightly emarginate in Malthine. crenulatus and Malthine. mushanus sp. nov.; outer lateral lobe of aedeagus: spoon-shaped, with a small sharp projection at the posterodistal end in Malthine. crenulatomimus, very thin and whip-like in Malthine. crenulatus, and divided into two parts, one of which is long and complex in shape, while the other is shorter and digitiform in Malthine. mushanus sp. nov.

Remarks. The two paratypes in NHMB were misidentified and recorded as Malthinus crenulatus by Wittmer (1984). Two specimens bearing the same label as the paratype from Meifeng were found in OMNH, but both were damaged and lacking the abdomen, making specific identification impossible.

This species is currently known only from Ren'ai Township, Nantou County, central Taiwan. At Chunyang, both Malthinellus crenulatomimus (Wittmer) and Malthine. crenulatus (Wittmer) were collected using the same malaise trap, and the former was obtained during the same period.

Distribution. Taiwan (Nantou).