Serangium xinpingensis Huang & Wang, 2024

Huang, Chu-Yang, Zeng, Li-Ling, Fan, Wu-wei, Lin, Ping, Dong, Qi-Jin, Su, Yu-Long & Wang, Xing-Min, 2024, A new species of the genus Serangium Blackburn (Coleoptera, Coccinellidae) from China, with description of the immature stages, ZooKeys 1210, pp. 197-206 : 197-206

Serangium xinpingensis Huang & Wang sp. nov.

Diagnosis.

This species can be identified by its brown body, dark-brown pronotum with sparse setae and two subparallel longitudinal rows of punctures along the lateral elytral margin, and body integument covered with long, thin setae (Fig. 2 a ); the penis is strongly arched (Fig. 3 b ).

This species is very similar to Serangium clauseni ( Chapin, 1940) and Serangium parcesetosum Sicard, 1929 , but it differs from S. clauseni in its more arched penis, squarer bases of parameres, and abdominal ventrite 1 with more densely incised punctures ( Wang et al. 2011). It is distinguished from S. parcesetosum by its more sharply angular antennomere 2 and curvature of its penis ( Booth and Polaszek 1996).

Description of adult.

TL: 2.04–2.35 mm, TW: 1.78–2.06 mm, TH: 1.28–1.34 mm, TL / TW: 1.14–1.15; PL / PW: 2.31–3.35; EL / EW: 1.84–1.87.

Body hemispherical; dorsum strongly convex (TH: 1.28–1.34 mm), glabrous (Figs 2 a – c ). Head brown or reddish-brown. Pronotum brown or reddish-brown, with black margins. Scutellum light brown. Elytra brown, slightly paler than head and pronotum, with one dark-brown band-like marking present along lateral margin; surface with sparse, shallow punctures, demonstrating one row along suture and two subparallel longitudinal rows along lateral margin (Fig. 2 a, b ).

Head transverse and ventrally flattened, 0.41 × elytral width (HW / EW = 2.45). Frons with long sparse setae. Eyes large and coarsely faceted, greatest interocular distance 0.36 × of head width. Antenna with nine antennomeres, terminal antennomere large, and spatulately elongate (Fig. 2 h ).

Pronotum short and strongly transverse, 0.69 × of elytral width (PW / EW = 1.96), sparsely covered with long setae. Prosternum with dense setae along anterior margin; prosternal process apically rounded.

Male genitalia. Penis strongly curved, arched, gradually narrowing, with blunt tip (Fig. 3 b ); penis capsule with one small inner process and concave on outer margin (Fig. 3 b ). Penis guide relatively slender and elongated, wide at base in ventral view, narrowing near distal 1 / 3 and having tongue-like shape; thin in lateral view, gradually tapering (Fig. 3 d ). Parameres asymmetrical; one extending from base to approximately 1 / 3 of penis guide, tapering apically, bearing few long setae; another extending from base to approximately 2 / 3 of penis guide, wider at base and gradually narrowing apically, with blunt tip, covered with small protuberances and setae (Fig. 3 d ).

Female genitalia. Genital plate (coxites) subtriangular (Fig. 3 f ), rounded at apex, bearing sparse setae; styli rather long (Fig. 3 f ), with few setae. Spermatheca consisting of two parts, including one globular, with faint constriction and two small pinch-like projections, and another elongate tubular shaped, slightly tapering distally (Fig. 3 e ).

Description of fourth instar larva.

Length 2.98 mm; width 1.34 mm. Body fusiform, bright yellow overall, dorsal surface with two longitudinal rows of pigmented spots laterally, long setae concentrated on body sides and with sparse, short setae on dorsum.

Head subovoid. Mouthparts light brown; frontal arms U-shaped, distinct. Three bulging stemmata presented on each side at antennal insertions, arranged in triangle (Fig. 5 e ). Antenna with two antennomeres, antennomere 2 twice as long as antennomere 1, with one long apical sensorium (ca 26.2 μm) and inconspicuous papillae (Fig. 5 e ). Mandibles heavily sclerotized, subtriangular, without basal tooth, but with one long seta at condyle (Fig. 5 g ). Maxillae subtriangular (Fig. 5 i ). Maxillary palp 3 - segmented, palpomere 3 nearly subequal in length with palpomere 2, elongate, with sensilla at apex (Fig. 5 j ), mala transverse and with anterior margin rounded (Fig. 5 i ). Labrum nearly trapezoidal, with sparse setae on anterior margin. Labium with sparse tomentum and four long setae evenly spaced around apex (Fig. 5 f ). Labial palps moderately separated, 2 - segmented, palpomere 2 distinctly longer than palpomere 1 (Fig. 5 j ).

Thorax with parallel anterior and posterior margins of each segment, strongly convex on lateral margins; laterally with pigmented spots, bearing long setae. Prothorax narrower than meso- and metathorax, meso- and metathorax almost equal in length and width. Tibiotarsus light brown, elongate, and translucent, with sparse setae; tarsal claws sickle-shaped; basal teeth subtriangular, with one long seta at base (Fig. 5 h ).

Abdomen 9 - segmented, each segment with lateral margin strongly convex, pigmented spots, bearing setae (Fig. 5 a, b ).

Description of pupa. Length 2.73 mm; width 2.11 mm. Body oval, light yellow, bearing flexible setae.

Type materials.

Holotype: 1 ♂, China, Yunnan: Musha Township, Yuxi , 23.8507 ° N, 101.7782 ° E, ca 475 m elev., 22. v. 2023, Huang CY leg ( SCAU) . Paratypes (15): 9 ♂♂ 6 ♀♀, same data as holotype ( SCAU) .

Distribution.

China (Yunnan).

Etymology.

The species epithet “ xinpingensis ” refers to the Xinping County where the type series was collected.

Remarks.

This is the first time that individual variation in appearance was found in Serangium . Based on our examination of 16 specimens, the male genitalia are highly uniform. The species displays distinct intraspecific variations in the coloration of adults. The head and pronotum coloration frequently subuniform, while the elytra along suture and outer margins may vary from brown to blackish-brown among individuals (Fig. 4 ).

Larvae of the subfamily Microweiseinae have been given little attention, and only two species have been recorded so far, namely Scymnomorphus japonicus (Kamiya, 1960) and Serangium japonicus Chapin, 1940 , belonging to the tribes Microweiseini and Serangiini , respectively. The larva of Scymnomorphus japonicus was described by Kamiya (1965) and Sasaji (1968), although it was originally described under the name Sukunahikona japonicus Kamiya, 1960 . The known larvae of the two tribes Serangiini and Microweiseini are very similar, but they differ greatly in the antennomere 2, which is much shorter in the tribe Microweiseini than Serangiini ( Kamiya 1965) . Within the tribe Serangiini , the larva of the new species can be distinguished from S. japonicus by its distinct U-shaped frontal arms. In S. japonicus , the frontal arms are invisible (Jiaming Zhuang pers. obs.)

Figures

Figure 2. Serangium xinpingensis sp. nov. a – c habitus photos: a dorsal view b lateral view c front view d prothorax, ventral view e maxilla, ventral view f labium, ventral view g mandible, dorsal view h antenna, dorsal view i posterior leg, ventral view. Scale bars: 0.2 mm (a – d, i); 0.1 mm (e, h); 0.05 mm (f, g).

Figure 3. Genitalia of adults of Serangium xinpingensis sp. nov. a abdomen, ventral view b – d male genitalia: b penis, lateral view c tegmen, ventral view d tegmen, lateral view e – f female ovipositor: e spermatheca f coxites, ventral view. Scale bars: 0.2 mm.

Figure 4. Habitus of adults of Serangium xinpingensis sp. nov., lateral view, showing intraspecific variations of the band-like marking along the outer margin of elytron. Scale bar: 0.2 mm.

Figures 5. The fourth instar larva and pupa of Serangium xinpingensis sp. nov. a fourth instar larva, dorsal view b fourth instar larva, lateral view c pupa, dorsal view d – j larval structures: d head capsule, dorsal view e antenna, dorsal view f labrum. dorsal view g mandible, dorsal view h tibiotarsus and claw. dorsal view i maxillary mala, ventral view j mouthparts, ventral view. Scale bars: 1 mm (a – c); 0.05 mm (d – f, h – j); 0.025 mm (g).