Holotype , 1♂, China, Tibet Autonomous Region, Dengba village, Mangkam County, Qamdo city, 3437 m, 29°32.406'N, 98°13.425'E, 18.IX.2019, Leg. Huo Qing-Bo (ICYZU). Paratypes, 6♂♂, 6♀♀, data same as holotype (Figs 7, 8); 5♂♂, 17♀♀, Yunnan Province, Diqing Tibetan Autonomous Prefecture, Shangri-la city, on the way from Diqing to Gezan Township, 3445 m, 27°45.656'N, 99°56.374'E, 7.IX.2019. Leg. Huo Qing-Bo (ICYZU); 2♂♂, 4♀♀, China, Yunnan Province, Diqing Tibetan Autonomous Prefecture, on national highway (G214) near Tongduishui and Deiyong Benglao, 3432 m, 28°18.282'N, 99°8.472'E, 9.IX.2019, Leg. Huo Qing-Bo (ICYZU); 1♂, 2♀, China, Yunnan Province, Diqing Tibetan Autonomous Prefecture, on national highway (G214) near Zhubagong, Deqin County (Fig. 7), 4027 m, 28°23.885'N, 98°59.143'E, 10.IX.2019, Leg. Huo Qing-Bo (ICYZU).

The new species is characterized by the sclerotized median sclerite of tergum X and its aedeagus armature. The shape of the median sclerite of tergum X resembles a turtle or a hexagonal star. The aedeagus, with a large distinct sclerite divided into an eagle-shaped trifurcate structure, the large median sclerite, and one pair of wing-shaped lateral sclerites on both sides, is diagnostic (Figs 2–4).

Adult habitus (Fig. 1A). Adult body length 8.5–9.5 mm (N = 10), forewing length 6.5–7.5 mm, hindwing length 5.5–6.5 mm. General color of body pale yellow in alcohol. Triocellate, head yellowish-white to yellowish-brown. Ocellar triangle and frontoclypeal area pale yellowish-brown, antenna pale brown, covered with small brown to dark brown setae. Pronotum disc margins covered with dark brown bands and with a thin dark medial stripe (Fig. 2A). Legs pale brown, mesonotum and metanotum with a distinct dark brown U-shaped marking, wings hyaline with yellow venation. Abdominal terga I–VIII with a wide medial trapezoidal dark brown stripe, slightly constricted medially on terga VII and VIII (Figs 1A, 2C–D).

Figure 1. 

Suwallia dengba sp. nov. A male habitus B female habitus.

Male (Figs 2–4). Tergum IX concave medially with semicircular stripe anteriorly, posteriorly covered with dark brown, thick hairs. Tergum X divided, median portion with a distinct dark brown sclerite resembling a turtle or hexagonal star in dorsal view (Figs 2C, 6A). Hemitergal processes sclerotized, with tiny hairs, finger-shaped and curved forward. Epiproct membranous, circular, knob-like, covered with minute hairs. Sternum IX ventrally extended anteriorly (Fig. 2D). Aedeagus membranous with a distinct sclerotized sclerite after eversion. Aedeagal sclerite resembling an eagle, divided into a trifurcate structure, a large median sclerite, and one pair of lateral sclerites (Figs 3A, 4A–D, 6B). Lateral sclerites armed with minute scales. Membranous part of aedeagus with fine cuticular asperities (Fig. 3A–D).

Figure 2. 

Suwallia dengba sp. nov. Holotype male A head and prothorax, dorsal view B head and prothorax, ventral view C terminalia, dorsal view D terminalia, ventral view.

Figure 3. 

Suwallia dengba sp. nov. Male paratype. A terminalia with aedeagus, dorsal view B aedeagus everted, dorsal view C aedeagus, caudal ventral view D aedeagus, ventral view.

Female. Adult habitus (Fig. 1B). Body length 9.0–10 mm (N = 10), forewing length 7.5–8.5 mm, hindwing length 6.5–7.5 mm. General body color, shape and appearance similar to those of male. Head and pronotum similar. Dorsal segment of abdomen with trapezoidal dark brown stripe extended to sternum VIII, subgenital plate large, extending to posterior portion of sternum IX, constricted from base, expanded medially, then slightly tapering toward posterior margins. Subgenital plate covered with minute, fine hairs. Tergum X not produced posteriorly. Paraproct in the shape of a small triangle, bearing small hairs (Fig. 5A–C).

Figure 4. 

Suwallia dengba sp. nov. A aedeagus B terminalia, lateral view C aedeagal sclerite, dorsal view D aedeagal sclerite, ventral view.

Figure 5. 

Suwallia dengba sp. nov. Female paratype. A terminalia, ventral view B terminalia, ventral view C terminalia, dorsal view.

Unknown.

Southwestern China (Tibet and Yunnan Province).

The species is named after the type locality, Dengba village.

The new species is closely related to Suwallia talalajensis, but can be distinguished by the sclerotized portion between the hemitergal processes, the pigmentation of tergum IX, the armature of the aedeagus and the well-developed, membranous, knob-like epiproct. Suwallia talalajensis does not have a distinct aedeagal sclerite (Li et al. 2015b: fig. 5), whereas the new species has a distinct sclerite (Figs 4A–D, 6B). Tergum IX of the new species is covered with abundant, thick hairs, and its body pigmentation is different from that of Suwallia talalajensis. The new species also shows similar characteristics to Suwallia errata (Li et al. 2021), but it can be easily differentiated by the sclerotized portion between the hemitergal process and the shape of the aedeagus. Suwallia errata has a V-shaped aedeagal sclerite (Li et al. 2015a: figs 1–6), but the new species has the aedeagal sclerite of a different shape. The new species lives in fast-flowing rivers (width = 5 m), where a large gravel substrate is present. The adults occur on leaves of trees or shrubs near the river (Fig. 8).

Figure 7. 

Revised map showing distribution of Suwallia species in China (modified from www.tianditu.gov.cn).

Figure 6. 

Suwallia dengba sp. nov. A male terminalia, dorsal view B aedeagal sclerite.

Figure 8. 

Habitat at the type locality of Suwallia dengba sp. nov. Specimens were collected from the small trees and grasses near the stream (photograph Huo Qing-Bo).