Tasactes ocellatus 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 ocellatus Lü & Zhang sp. nov.

Figs 5 , 6 Chinese common name: 小眼杯象 [xiăo yăn bēi xiàng ]

Material examined.

Holotype: ♂, labelled: printed: 西藏 林芝市 墨脱县 背崩乡 阿苍村 [ Xīzàng, Línzhīshì, Mòtuōxiàn, Bèibēngxiāng , Acāngcūn ] / 2019. VIII. 09 // 29.2453°N, 95.1300°E / Alt. 1409 m / 周润 [ Zhōu Rùn] 马茁 [ Mă Zhuó] leg. // printed: IOZ (E) 1965695 . Paratypes: 2 ♀, same data as holotype, but printed label: IOZ (E) 1965696 and IOZ (E) 1965697 respectively .

Type locality.

Acang Village, Beibeng Township, Medog County, Linzhi City, Xizang Autonomous Region, China.

Comparative diagnosis.

Tasactes ocellatus sp. nov. is most similar to T. carinulatus but differs in the following characters: (i) body smaller (length 3.65–3.89 mm, width 1.66–1.68 mm vs length 4.20 mm, width 1.80 mm in T. carinulatus ); (ii) rostrum shorter than pronotum in both sexes, whereas longer than pronotum in T. carinulatus ; (iii) pronotum lacking basal transverse depression, while distinct basal transverse depression present in T. carinulatus ; (iv) elytral punctures subequal in size to pronotal punctures, while 2.0 times as large as pronotal punctures in T. carinulatus . Tasactes ocellatus sp. nov. geographically closest to T. angustus sp. nov., both occurring in Medog County, but differing in: (i) eyes barely visible ventrally, versus distinctly visible in T. angustus sp. nov.; (ii) rostrum shorter ( Rl 0.95–1.05 mm vs Rl 1.00– 1.45 mm in T. angustus sp. nov.); (iii) antennal scape shorter and stouter (l / w3.78 vs l / w 4.42 in T. angustus sp. nov.); (iv) pronotum sides subparallel, versus sides curved in T. angustus sp. nov.; (v) elytral interstriae 1–3 flat, bearing pilose pustules, whereas uniformly convex, lacking pustules in T. angustus sp. nov.; (vi) pedon apex acutely narrowed, manubrium shorter than temones, while apex slightly narrowed, manubrium subequal to temones in T. angustus sp. nov.; (vii) basal arms of spiculum gastrale slender and linear, as compared to subtriangular in T. angustus sp. nov.; (viii) styli width approximately 1 / 4 width of gonocoxite apices, while 1 / 2 in T. angustus sp. nov.

Description.

( holotype, except female sternite 8 and genitalia).

Coloration (Fig. 5 A, B ). Body entirely black; antennal scape and funicle, and tarsomeres reddish brown.

Head (Fig. 5 C – E ). Forehead flat, 0.5 times width of rostrum at base; eyes small, oval, barely visible ventrally; rostrum elongate ( Rl / Rw 1.96), shorter than pronotum ( Rl / Pl 0.73), slightly curved in lateral view, base thick, densely covered with punctures, bearing short pubescence; antennae inserted slightly anterior to middle of rostrum; scape long (l / w3.78), not reaching eyes, gradually widening from base to apex, middle markedly widened; funicular segments 1 and 2 elongate, segment 2 funnel-shaped, segments 4–6 transverse; club subobconical (l / w1.64).

Pronotum (Fig. 5 F ). Longer than wide ( Pl / Pw 1.18), widest at middle, apical 1 / 5 distinctly constricted, sides subparallel; disc slightly convex in lateral view, with dense and coarse punctures; distance between punctures slightly exceeding puncture diameter, punctures sparser on disc than laterally; densely covered with short pubescence; postocular lobes absent.

Scutellum. Very small, subtriangular.

Elytra. Longer than wide ( El / Ew 1.44), widest at basal 1 / 4, sides rounded; disc slightly convex in lateral view; interstriae slightly convex, subequal in width, interstriae 3 and 5 basally, interstriae 1–5 from middle to apex bearing pilose pustules forming indistinct V-shaped pattern; striae deep, punctures rounded, bearing dense, short pubescence; distance between punctures slightly exceeding puncture diameter.

Abdomen (Fig. 5 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 0.6 times length of ventrite 1, ventrite 3 slightly longer than ventrite 4, ventrite 5 2.3 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 3.9 times as long as wide; tibiae bearing single long uncus; protibia 5.7 times as long as wide; tarsi long, tarsomeres 1–3 obconical, ventrally with erect setae, onychium elongate; claws free, divergent; protarsomere 1 1.7 times as long as wide, tarsomeres 2 and 3 each 1.1 times, onychium 4.2 times.

Male genitalia (Fig. 5 H – K ). Pedon 0.3 times length of temones, evenly curved in lateral view, sides subparallel, base symmetrical, apex distinctly narrowed; temones slender, slightly curved; manubrium of tegmen long, 0.7 times length of temones, slightly curved, wider than temones; spiculum gastrale robust, evenly curved; basal plate bifurcate, basal arms slender, opposed, apices acute.

Female sternite 8 and genitalia (Fig. 6 G – I ). Sternite 8 with apodeme 1.5 times length of lamina; lamina bifurcate at base, sides curved and depressed, apex with sparse setae; gonocoxites cylindrical, apices with dense setae; styli short, cylindrical, width approximately 1 / 4 width of gonocoxite apices, apices with short setae; spermatheca with robust and curved cornu; corpus large; ramus and collum not developed.

Variation.

Male holotype. Measurements (in mm): Bl: 3.89. Rl: 0.98, Rw: 0.50. Pl: 1.33, Pw: 1.13. El: 2.38, Ew ( Bw): 1.68.

Female paratypes. Measurements (in mm) ( n = 2): Bl: 3.65–3.85 (3.75). Rl: 0.95–1.05 (1.00), Rw: 0.39–0.40 (0.40). Pl: 1.24–1.3 (1.27), Pw: 1.09–1.01 (1.10). El: 2.10–2.35 (2.23), Ew ( Bw): 1.55–1.65 (1.60). Illustrations of a female are provided (Fig. 6 A – I ).

Female rostrum slenderer than that of male; male antennae inserted slightly anterior to middle of rostrum, female antennae inserted at middle of rostrum; ventrites without distinct differences between sexes.

Distribution.

Known only from the type locality in Xizang, China (Fig. 9 ).

Etymology.

The species name is a Latin masculine adjective ocellatus (having small eyes), referring to the significantly reduced eyes compared to other species within the genus.

Figures

Figure 5. Tasactes ocellatus sp. nov., holotype male. A. Habitus dorsal; 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 6. Tasactes ocellatus sp. nov., paratype female (IOZ (E) 1965696). 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).