Sphaeroderma hsui sp. nov.

Figs 2A, 3, 4

Types.

Holotype ♂ (TARI). Taiwan: Miaoli, Hsiaopangchih (小胖池), 28.VIII.2021-16.XI.2021, leg. Y.-F. Hsu. Paratypes. 29♂, 22♀ (TARI: 26♂, 19♀; BMNH: 3♂, 3♀), same data as holotype; 4♂, 2♀ (TARI), same but with “28.VIII.2021”; 2♂, 3♀ (TARI), same but with “21.V.-28.VIII.2021”; 1♀ (TARI): Hsishihshan (西勢山), 16.XI.2021-21.IV.2022, leg. Y.-F. Hsu.

Description.

Length 2.5-2.8 mm, width 1.6-1.9 mm. Body color (Fig. 3A-C) yellowish-brown. Antennae filiform in males (Fig. 4A), antennomeres VIII-X wider, length ratios of antennomeres I-XI 1.0:0.6:0.4:0.5:0.7:0.6:0.7:0.8:0.7:0.7:1.0, length to width ratios of antennomeres I-XI 2.9:2.1:1.8:2.0:2.5:2.4:2.5:2.6:2.3:2.3:3.0; similar shape in females (Fig. 4B), but antennomeres VIII-X narrower, length ratios of antennomeres I-XI 1.0:0.6:0.4:0.5:0.8:0.6:0.8:0.7:0.7:0.7:1.0, length to width ratios of antennomeres I-XI 3.1:2.3:1.9:2.2:3.2:2.6:2.9:2.5:2.4:2.2:3.3. Antennal calli longitudinal, with supracallinal sulci poorly delimited. Pronotum 1.7-1.9 × wider than long, disc with fine, scattered punctures, same size as punctures on elytra; lateral margins almost straight; anterolateral callosity protruding forward; posterolateral callosity poorly developed. Elytra 1.3 times longer than wide, sides widely rounded; disc with punctures entirely confused; humeral calli well developed. Abdominal ventrite V without internal median ridge in both sexes. Male genitalia: aedeagus (Fig. 4C, D) slender in dorsal view, 4.0 × longer than wide; parallel-sided, but slightly narrowed at apical 1/4, apex widely rounded; moderately curved at middle in lateral view, apex slightly recurved, ventral margin with densely, tiny teeth at middle; ostium membranous and with Y-shaped sclerotized area. Female genitalia: ventrite VIII (Fig. 4E) with apical part triangular, apical margin smooth and lacking setae, disc with medial part membranous, spiculum short; gonocoxae (Fig. 4G) separated, transversely triangular, with dense, long setae along apical margins, with one slender and transverse basal sclerite; receptacle of spermatheca (Fig. 4F) moderately swollen; pump short and strongly curved, transverse wrinkles present on entire pump and extending into half of receptacle; sclerotized proximal spermathecal duct long, with ramus oblong.

Color variation.

Some adults have black bodies (Fig. 3D-F) with legs and antennae that are yellowish-brown, with metafemora darkener; some adults (Fig. 3G-I) similar in this color form, but the elytra are yellowish-brown except darker base that extends to lateral margins, then abbreviated at apical 1/3.

Diagnosis.

Although adults of Sphaeroderma hsui sp. nov. display diverse color patterns (Fig. 3), they are characteristic and diagnostic. In addition, this new species differs from the two other Taiwanese species ( S. changi sp. nov. and S. sheipaensis sp. nov.) based the following combination characters: entire yellowish-brown antennae (Fig. 3) [yellowish-brown antennomeres I-IV and black antennomeres V-XI in other species (Fig. 5)]; longitudinal antennal calli with poorly delimited supracallinal sulci (Fig. 2A) [transverse antennal calli with well-developed supracallinal sulci in S. changi sp. nov. (Fig. 2B) and S. sheipaensis sp. nov. (Fig. 2C)]; slender aedeagus, 4.0 × longer than wide, with cluster of setae at middle of inner margin in lateral view (Fig. 4D) [wide aedeagus, 3.1 × longer than wide, and inner margin lacking setae in lateral view in S. changi sp. nov. (Fig. 6D)]; triangular abdominal ventrite VIII in females with apical margin lacking setae, subapically and moderately narrowed sides (Fig. 4E) [apical margin with seven pairs of setae at medial part in S. changi sp. nov. (Fig. 6E), subapically and slightly narrowed sides in S. changi sp. nov. and S. sheipaensis sp. nov. (Figs 6E, 7E)]; transversely triangular gonocoxae (Fig. 4G) [longitudinally triangular gonocoxae in S. changi sp. nov. (Fig. 6G)].

Etymology.

The name is dedicated to Dr Yu-Feng Hsu (徐堉峰), who is the director for the insect survey project at Shei-Pa National Park.

Distribution.

Sphaeroderma hsui sp. nov. seems to be the dominant species at the Shei-Pa National Park.