Neoperla annulatispina Mo, Li & Wang 2021, sp. nov.

Neoperla annulatispina Mo, Li & Wang, sp. nov.

(Figs. 1–2)

Adult habitus (Fig. 1). Body color generally dark brown, abdomen pale. Head pale, with a prominent dark brown rectangular ocellar patch, and a smaller, semicircular spot interrupted by M-line; palpi brown; antennae generally brown, basal part paler; biocellate, the distance between ocelli ca. 2.0 X as wide as the diameter of the ocellus; head slightly wider than pronotum. Pronotum dark brown and rectangular, with scattered, dark rugosities and a pair of pale lateral areas; corners rounded. Wings brownish and transparent, veins dark brown; legs dark brown, basal two third of femora pale (Fig. 1e); cerci pale.

Male (Figs. 1b–1d, 2a–2e). Forewing length 11.0– 12.4 mm (N=3). Tergum 6 with a posteromedial patch of sensilla basiconica. Tergum 7 with an anteromedian pair of sclerotized, upraised, nipple-shaped processes and a distal rectangular process on posterior margin covered with sensilla basiconica. Tergum 8 with a recurved triangular process, fringed with small distal spines. Tergum 9 with two paramedial patches of long hairs. Hemitergal processes of tergum 10 upcurved, finger-like. Aedeagus mostly membranous, falciform (Figs. 2a–2e). Aedeagal tube mostly straight, only dorsal surface sclerotized (Figs. 2a, 2c–2d). Aedeagal sac slightly longer than tube and curved ventrally, forming a right angle to tube; dorsolateral surface with 2–3 irregular rows of small spines; subapical portion with a complete ring of small spines; apical surface densely covered with tiny spinules; apical portion with a H-shaped, dark uneverted flagella (Figs. 2a–2e).

Female (Figs. 2f– 2g). Forewing length 13.0– 14.5 mm (N=2). Habitus generally similar to male except dark brown marking on head is more extensive. Sternum 8 lightly sclerotized; the posteromedial margin slightly produced forming a small quadrate sclerotized subgenital plate.

Eggs. Available females were void of matured eggs.

Type Material. Holotype: male (HIST), China: Guangdong Province, Shaoguan City, Chebaling National Nature Reserve, Xiba, N 24°43’48”, E 114°15’36’’, 360 m, 2016.V.1, light trap, Luo, Liu, Xun & Zhao. Paratypes: 1 male and 1 female (CAU), 1 male and 1 female (HIST), same locality and date as holotype.

Etymology. The specific name refers to the ringed section of small spines of aedeagus. Latin “annulatus” means ringed and “spina” means spine.

Distribution. China: Guangdong, Chebaling National Nature Reserve (Fig. 15). The exact habitat is unknown.

Remarks. The new species is a member of the Neoperla montivaga species group (Zwick 1983). The new species shares similar head pattern, terminalia and aedeagus with N. nigromarginata Li & Zhang, 2014 known from Henan Province of Central China. However, the new species can be separated from the latter by the following features: the paired lateral pale area of pronotum is smaller; aedeagal sac only with 2–3 irregular rows of small spines in dorsolateral surface; subapical spinous ring is complete; paired apical flagella is linked by a short sclerotized band. In N. nigromarginata, the paired lateral pale area of pronotum is bigger, comprising about 50% of the total surface; aedeagal sac with 2–3 irregular rows of small spines in dorsal surface and a large lateral patch of small spines, without subapical spinous ring or the ring is not complete; paired apical flagella are not connected. In addition, subgenital plate of female sternum 8 of N. nigromarginata has a small median notch at posterior margin, while the subgenital plate of the new species lacks a median notch.

The COI sequence of Neoperla annulatispina Mo, Li & Wang, sp. nov. and N. nigromarginata had a consistent length of 659 bp, and both biased toward A and T nucleotides (N. annulatispina: 26.0% A, 21.3 C, 18.6% G and 34.1% T; N. nigromarginata: 26.3% A, 21.7 C, 18.1% G and 34.0% T). The genetic distances were calculated for the 16 sequenced specimens (Table 2). In our study, pairwise distances of the two Neoperla species were 2.0–2.8%; with an average of 2.3%, slightly higher than 2% threshold considered for a rough differentiation between intraspecific and interspecific distances (Hebert et al. 2003; Zhou et al. 2009). The minimum and average interspecific sequence divergences of the two species are higher than the maximum intraspecific sequence divergences (0.6–1.1%) without overlap (Table 2). In the Neighbor-joining (NJ) tree (Fig. 3), male and female specimens of N. annulatispina are grouped in the same clade, separated from the clade of male and females of N. nigromarginata. The combination of morphology and molecular data suggest that N. annulatispina is a new species to science.