Cephalaeschna flabellata, Yang & Zhang, 2025

Cephalaeschna flabellata sp. nov.

Holotype. male, Mt Luoping ( 26.01 N, 99.91 E), Eryuan County, Bai Autonomous Prefecture of Dali, Yunnan Province, China, altitude 2405m, Guo Li leg., 7 July 2024. GoogleMaps

Paratype. 1 female, same locality, Guohui Yang leg., 4 August 2021 ; Paratypes, 2 females, same locality as holotype, Dongdong Zi leg., 14 July 2021 GoogleMaps ; 1 male, Shuanghe Stream ( 26.59°N, 99.88°E), Jinhua Town , Jianchuan County, Bai Autonomous Prefecture of Dali, Yunnan Province, China, altitude 2350 m, Guohui Yang leg., 6 August 2023 GoogleMaps .

Etymology. The species name flabellata (Latin = fan shaped) refers to the fan-shaped greenish-yellow spots on the anterodorsal surfaces of abdominal segments 3–7, a diagnostic feature of this species.

Description of the holotype

Head. Labium yellowish-green with broad black marginal band ( Fig. 1a View FIGURE 1 ). Labrum black with a pair of semicircular pale blue spots sometimes partially coalesced ( Fig. 3a View FIGURE 3 ). Anteclypeus mostly pale yellow on the upper part with brown marking. Postclypeus brown with bluish-yellow tints on lower part, bearing pale brown pits. Antefrons brown, darker on the upper frontal and dorsal sides, with an obtuse dorso-frontal apex; its width approximately 0.66 times the distance between the compound eyes, lacking a T-shaped mark dorsally. Vertex and antennae black ( Fig. 1b View FIGURE 1 ). Compound eyes in life are intense sapphire blue, margined with yellow. Frons and occiput with long blackish hairs ( Figs. 1a–b View FIGURE 1 ; 3a View FIGURE 3 ; 4a–b View FIGURE 4 ).

Thorax. Prothorax dark brown, with long black setae. Synthorax dark brown with greenish- yellow markings as follows: dorsal carina entirely black, dorsal stripes on mesepisternum slightly tapered anteriorly ( Fig. 1c View FIGURE 1 ). Two lateral stripes broad and yellow, becoming green ventrally; the anterolateral (humeral) stripe broken into two spots, the lower one larger and connected to the upper by a fine line (or broad patches). A small triangular green spot present near the subalar ridge, below a quadrangular spot at forewing base, and a small oval-shaped yellowish-green spot beneath the metastigma. Metepimeron with a broad triangular band, predominantly greenish-yellow, separated by a fine line from a green spot at hindwing base ( Fig. 1d View FIGURE 1 ). Legs dark brown to black, except for the proximal parts of all femora, which are dark brown ( Figs. 1d View FIGURE 1 , 4b View FIGURE 4 ). Wings hyaline, with light greyish tint, with a black pterostigma covering 2.5 cells. Antenodal cross-veins (Ax) 19 in both forewings (Fw), 15 (right) and 16 (left) in hindwings (Hw); postnodal cross-veins (Px) 14 in both Fw, 14 (right) and 16 (left) in Hw; The forewing triangle 4-celled, the hindwing triangle 4–5-celled; anal loop 8-celled, and anal triangle 5-celled. The wing venation is shown in Fig. 1e View FIGURE 1 .

Abdomen. Dark brown to black, marked with light green and yellow: S1 with a narrow dorsal bluish-green band and a quadrangular greenish patch on each side; S2 with a yellow ventral auricle, a narrow greenish-yellow mid-dorsal stripe discontinuous medially, and with paired bluish-green triangular MD spots, and paired thin bluish-green strip PD spots; S3–8 with a single fan-shaped AD, a pair of triangular MD spots almost connected medially (linking to the AL spot), and paired small thin PD spots separated medially; S9 with paired thin AD spots and small paired thin PD spots; S10 with a small dorsal bluish-green band, a pair of irregular AD spots, and with a pair of small circular AL spots ( Figs. 2a–b View FIGURE 2 , 4a–b View FIGURE 4 ).

Anal appendages. Completely black. Superior appendages approximately 1.8 times the length of S10, with long fine hairs on the inner margin and small setae on the outer edges. In lateral view, the blunt rounded end curves upward without obvious narrowing ( Fig. 2c View FIGURE 2 ); in dorsal view, they expand in the apical 2/3, appearing broadest at middle and ending with an upward curve. Inferior appendage about 2/3 the length of superior appendages, gradually up-curved ( Fig. 2d View FIGURE 2 ).

Secondary genitalia. Base of the penis dark brown, and the glans creamy white. Tip of the glans darkened dorsally. Two nearly transparent filaments (approximately twice the length of the glans) gradually diverging toward the tip of the glans ( Fig. 2e– f View FIGURE 2 ).

Description of Female

Head and thorax. Very similar to the male ( Figs. 2g View FIGURE 2 ; 3b View FIGURE 3 ; 4c–d View FIGURE 4 ).

Wings. Hyaline with base slightly tinted smoky brown. Pterostigma light brown, with its leading edge black, covering 2.5 cells in forewing, and 2 cells in hindwing ( Figs. 2g View FIGURE 2 , 4c View FIGURE 4 ). Triangle 4- or 5-celled in forewings, and 5- celled in hindwings; anal loop 8- or 9-celled. Antenodal cross-veins (Ax) 22 (right) and 21 (left) in forewings (Fw), and 18 (both) in hindwings (Hw). Postnodal cross-veins (Px) 17 (right) and 18 (left) in Fw, 18 (right) and 17 (left) in Hw.

Abdomen. Markings similar to those of the male, with the following differences: S8 with paired AD stripes; S9 has an additional small AD spot, a brown dorsal terminal stripe, and large yellow-green lateral stripe (in living specimens). Superior appendages dark brown to black, 1.6 times longer than S10. Ovipositor short, brownishyellow, not exceeding the end of the abdomen, and reaching only to midpoint of superior appendages ( Figs. 2h View FIGURE 2 , 4c–d View FIGURE 4 ).

Measurements (mm)

Holotype: total length 61.0; abdomen (including anal appendages) 46.5; hindwing 41.0.

Paratype female: total length 59.5; abdomen (including anal appendages) 45.5; hindwing 46.0. Paratype males: total length 62.5; abdomen (including anal appendages) 47.0; hindwing 42.0. Paratype females: total length 60.5– 61.0; abdomen (including anal appendages) 46.0–47.5; hind wing 45.0–47.0.

Variation in paratypes

Compared with the paratype male, the other males exhibit only slight variations in wing venation (Ax 20 in Fw, 17 and 14 in Hw; Px 14 [right] and 16 [left] in Fw, 14 and 15 in Hw) and anal loops (7-celled). As adults advance in maturity (both male and female), body ground-colour transitions from brown to black with progressive darkening of wing, and the pair of pale blue spots on the labrum gradually enlarge ( Fig. 3a–d View FIGURE 3 ).

Distribution

China ( Bai Autonomous Prefecture of Dali , Yunnan and Lijiang City, Yunnan) .

Notes on biology

This species lives in high-altitude mountain streams ( 2300–3200 m a.s.l.). Most individuals are active on sunny afternoons, adult males patrol along turbulent streams and can sometimes be seen hovering close to the water surface, defending their territory, flight season from July to October. Larvae were also abundant at the type locality, usually under the stream substrate or at the roots of aquatic plants along the banks.

Diagnosis

Both sexes of this species were collected on the same occasion in Dali, Yunnan Province. The body maculation of male specimens matches well with the description and illustrations of Cephalaeschna sp. 1 in Zhang (2019); the female possesses very similar head morphology and coloration. In 2024, the corresponding author collected Cephalaeschna specimens (both sexes) from Yunlong Mountain in Lijiang city, Yunnan. Compared with the specimens collected in Dali before ( Cephalaeschna sp. 1 ), except for the slightly different individual patterns in anterolateral synthorax (anterolateral stripe broken into two spots replaced [from Dali] by broad patches in anterolateral synthorax [from Lijiang City], other characteristics such as secondary genitalia, anal appendages, the shape and length of female ovipositor, and abdominal patterns were consistent and identified as the same species ( Figs. 1d View FIGURE 1 , 2g View FIGURE 2 , 4 View FIGURE 4 ).

Cephalaeschna flabellata (both sexes) has a unique abdominal colour patterns (with a single fan-shaped spot on anterodorsal segments 3–7), a diagnostic character distinguishing it from all other known Cephalaeschna species. This species is not closely allied to any Chinese Cephalaeschna species but in appearance it is very similar to C. patrai from India, both species share dark brown to black body, green and yellow thoracic stripes, blue eyes and bicolored legs ( Dawn 2021). However, C. flabellata differs from C. patrai by: (1) lacking middorsal lines on S3–7; and (2) the ovipositor of female being short, not extending beyond the end of the abdomen in C. flabellata (with fine green middorsal lines on S3–7 and ovipositor of female long, as long as end of the abdomen in C. patrai ).

Fifteen Cephalaeschna View in CoL species have been reported from mainland China ( Needham 1930; Asahina 1981a, b, 1982; Wilson 1999; Wilson & Xu 2008; Xu 2006; Zhang 2013; Zhang et al. 2013; Zhang & Cai 2013; Zhang 2019; Yang 2019). Cephalaeschna flabellata is the sixteenth member of the genus reported from China.