Tasactes angustus Lü & Zhang, 2025

Lü, Heyu & Zhang, Runzhi, 2025, Four new species of the genus Tasactes Faust, 1894 (Coleoptera, Curculionidae, Dryophthorinae) from China, ZooKeys 1256, pp. 141-161 : 141-161

Tasactes angustus Lü & Zhang sp. nov.

Figs 1 , 2 Chinese common name: 狭杯象 [Xiá bēi xiàng ]

Material examined.

Holotype: ♂, labelled: printed: 西藏 波密县 易贡乡 S 305 省道 11 公里处 [ Xīzàng, Bōmìxiàn, Yìgòngxiāng, S 305 Shěngdào 11 Gōnglĭchù ] / 30.1536°N, 94.9904°E / Alt. 2134 m / 2018. VIII. 1 / 周润 [ Zhōu Rùn] leg. // printed: IOZ (E) 1965680 . Paratypes: 6 ♂ 6 ♀, same data as holotype, but printed label: IOZ (E) 1965681 –1965687, IOZ (E) 1965689 –1965692, IOZ (E) 1965694 ; 2 ♂ 3 ♀, labelled: printed: 西藏 易贡 [ Xīzàng, Yìgòng ] / Alt. 2300 m / 1978. VII. 13, 17 / 李法圣 [ Lĭ Făshèng] leg. // printed: IOZ (E) 1507485 –1507488, IOZ (E) 1507491 ; 1 ♂ 4 ♀, labelled: printed: 西藏 波密 易贡 [ Xīzàng, Bōmì, Yìgòng ] / Alt. 2300 m / 1987. VIII. 17 / 韩寅恒 [ Hán Yínhéng] leg. // printed: IOZ (E) 1507489 , IOZ (E) 1507490 , IOZ (E) 1507492 –1507494 ; 1 ♀, labelled: printed: 西藏 林芝市 波密县 易贡乡 [ Xīzàng, Línzhīshì, Bōmìxiàn, Yìgòngxiāng ] / 30.2398°N, 96.8624°E / Alt. 2289 m / 2019. VII. 19 / 周润 [ Zhōu Rùn] 马茁 [ Mă Zhuó] leg. // printed: IOZ (E) 1965693 ; 1 ♀, labelled: printed: 西藏 林芝市 波密县 易贡乡 [ Xīzàng, Línzhīshì, Bōmìxiàn, Yìgòngxiāng ] / K 12 / 30.1506°N, 94.9952°E / Alt. 2097 m / 2019. VII. 20 / 周润 [ Zhōu Rùn] 马茁 [ Mă Zhuó] leg. // printed: IOZ (E) 1965688 ; 1 ♀, labelled: printed: 西藏 林芝市 墨脱县 墨脱公路 62 k 喜荣沟附近 [ Xīzàng, Línzhīshì, Mòtuōxiàn, MòtuōGōnglù, 62 k, Xĭrónggōufùjìn ] / 29.7110°N, 95.5881°E / Alt. 2749 m / 2019. VII. 24 / 周润 [ Zhōu Rùn] 马茁 [ Mă Zhuó] leg. // printed: IOZ (E) 1965689 .

Type locality.

Yigong Township (11 kilometres from S 305 provincial road), Bomi County, Linzhi City, Xizang Autonomous Region, China.

Comparative diagnosis.

Tasactes angustus sp. nov. morphologically is most similar to T. carinulatus , but distinguished by: (i) rostrum shorter than pronotum in both sexes, versus longer in T. carinulatus ; (ii) pronotum sides rounded, lacking basal transverse depression, while sides subparallel with distinct basal transverse depression in T. carinulatus ; (iii) elytral interstriae subequal in width and height, versus interstriae 1, 3, and 5 distinctly narrower and slightly lower in T. carinulatus ; (iv) elytra more elongate with apical 1 / 6 conspicuously constricted, whereas lacking constriction in T. carinulatus .

Description.

( holotype, except female sternite 8 and genitalia).

Coloration (Fig. 1 A, B ). Body entirely black; antennal scape and funicle, and tarsomeres reddish brown.

Head (Fig. 1 C – E ). Forehead flat, slightly narrower than rostrum at base; eyes elongate-oval, distinctly separated ventrally; rostrum elongate ( Rl / Rw 3.13), shorter than pronotum ( Rl / Pl 0.85), slightly curved in lateral view, base thick, basal 1 / 3 with dense short, pubescence and coarse punctures; antennae inserted slightly anterior to middle of rostrum; scape long (l / w4.42), not reaching eyes, gradually broadening from base to apex, apical 1 / 3 markedly widened; funicular segments 1 and 2 elongate, segment 2 funnel-shaped, segments 4–6 transverse; club subobconical (l / w3.25).

Pronotum (Fig. 1 F ). Longer than wide ( Pl / Pw 1.04), widest posterior to middle, apical 1 / 6 distinctly constricted, sides rounded; disc slightly convex in lateral view, with dense, coarse punctures, punctures sparser on disc than laterally; densely covered with short pubescence; postocular lobes absent.

Scutellum. Very small, elongate-oval.

Elytra. Longer than wide ( El / Ew 1.54), widest at basal 1 / 4, distinctly constricted at apical 1 / 6, sides rounded; disc nearly flat in lateral view; interstriae distinctly elevated, subequal in width, with dense, short pubescence; striae deep, punctures elongate-oval; distance between punctures subequal to a puncture length; punctures with dense short pubescence.

Abdomen (Fig. 1 G ). Abdominal ventrites densely covered with coarse punctures; ventrite 2 with anterior margin slightly convex at middle, posterior margins of ventrites 2–4 rectilinear; ventrite 2 0.8 times length of ventrite 1, ventrite 3 slightly longer than ventrite 4, ventrite 5 1.9 times as wide as long.

Legs. Densely covered with short pubescence; femora and tibiae with punctures; procoxae subconical, contiguous; profemur more robust than mesofemur and metafemur, femora unarmed; profemur 4.3 times as long as wide; tibiae bearing single long uncus; protibia 6.0 times as long as wide; tarsi long, tarsomeres 1–3 obconical, ventrally with dense erect setae, onychium elongate; claws free, divergent; protarsomere 1 1.7 times as long as wide, tarsomeres 2 and 3 each 1.3 times, onychium 4.0 times.

Male genitalia (Fig. 1 H – K ). Pedon 0.4 times length of temones, evenly curved in lateral view, sides subparallel, base symmetrical, apex slightly narrowed; temones slender, slightly curved; manubrium of tegmen long, evenly curved from middle to apex, slightly wider than temones; spiculum gastrale robust, evenly curved; basal plate bifurcate, basal arms opposed, upper part of each basal arm approximately triangular, length subequal to width, apices with rounded angles.

Female sternite 8 and genitalia (Fig. 2 G – I ). Sternite 8 with apodeme 1.5 times length of lamina; lamina bifurcate at base, sides slightly curved, apex with sparse setae; gonocoxites cylindrical, apices with dense setae; styli short, cylindrical, width approximately 1 / 2 width of gonocoxite apices, apices with setae; spermatheca with robust and curved cornu; corpus large; ramus and collum not developed.

Variation.

Male paratypes. Measurements (in mm) ( n = 9): Bl: 3.40–4.22 (3.87). Rl: 1.00–1.23 (1.16), Rw: 0.32–0.39 (0.36). Pl: 1.13–1.45 (1.30), Pw: 1.10–1.40 (1.26). El: 2.08–2.58 (2.40), Ew ( Bw): 1.35–1.69 (1.55).

Female paratypes. Measurements (in mm) ( n = 16): Bl: 3.50–4.40 (3.94). Rl: 1.10–1.45 (1.27), Rw: 0.30–0.48 (0.39). Pl: 1.10–1.50 (1.32), Pw: 1.08–1.47 (1.27). El: 2.20–2.50 (2.43), Ew ( Bw): 1.31–1.80 (1.53). Illustrations of a female are provided (Fig. 2 A – I ).

Male body slightly smaller than that of female; rostrum shorter in male; smooth from apical 1 / 3 to apex in male, smooth and shiny from middle to apex in female; antennae inserted slightly anterior to middle of rostrum in male, at middle in female; ventrites without distinct differences between sexes.

Distribution.

Bomi County and Medog County, Linzhi City, Xizang Autonomous Region, China (Fig. 9 ).

Etymology.

The species name is a Latin masculine adjective angustus (narrow), referring to the significantly narrower body width compared to other species within the genus.

Figures

Figure 1. Tasactes angustus sp. nov., holotype male. A. Dorsal habitus; B. Lateral habitus; C. Head, dorsal view; D. Head, lateral view; E. Eyes, ventral view; F. Pronotum, dorsal view; G. Ventrites, ventral view; H. Penis, lateral view; I. Penis, ventral view; J. Penis at apex, showing details of the pedon; K. Spiculum gastrale. Scale bars: 1 mm (A – D, F, G); 0.5 mm (H, I, K).

Figure 2. Tasactes angustus sp. nov., paratype female (IOZ (E) 1965681). A. Dorsal habitus; B. Lateral habitus; C. Head, dorsal view; D. Head, lateral view; E. Pronotum, dorsal view; F. Ventrites, ventral view; G. Sternite 8; H. Ovipositor; I. Spermatheca. Scale bars: 1 mm (A – F); 0.25 mm (G – I).

Figure 9. Distribution of Tasactes species in China (based on specimens examined in this study).