Siphlonurus zhelochovtsevi Tshernova, 1952

Qiang, Xin-He & Zhou, Chang-Fa, 2025, The species diversity and phylogeny of the genus Siphlonurus Eaton, 1868 from China (Ephemeroptera: Siphlonuridae), Zootaxa 5711 (1), pp. 1-56 : 41-44

Siphlonurus zhelochovtsevi Tshernova, 1952 (first record from China)

Figures 27–28

Siphlonurus zhelochovtsevi Tshernova, 1952: 263 (male imago, from Russia).

Siphlonurus zhelochovtsevi : Kluge 1985: 15 (all stages); Soldán et al. 2009: 655 (checklist).

Material examined: 10 nymphs, 60 ♀ imagos, 5♂ imagos, 1♀ subimago, 1♂ subimago, Erdao Baihe Town , Fusong County, Jilin Province, 23–25.VII.2008, Shilei Wang and Guo Zhao ; 2♀ imagos, Hunhe River, Fushun City , Liaoning Province, 41.28444348°N, 124.99140257°E, ca. 490 m, 29.VII.2023, Xinhe Qiang; 2 nymphs , 1♂ subimago, Laocaohe, Mohe City, Daxinganling District , Heilongjiang Province, 52.833392°N, 122.591656°E, ca. 480 m, 16–19.VII.2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun ; 1♀ imago, Dalin River, Mohe City, Daxinganling District , Heilongjiang Province, 52.968586°N, 122.269555°E, ca. 470 m, 16–19.VII.2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun ; 3♀ imagos, Genhe, Hexi Street, Genhe City , Hulunbuir City , Inner Mongolia, 50.796106°N, 121.578682°E, ca. 720 m, 19.VII.2024, Xinhe Qiang, Ningning Wang, and Yuxian Sun ; 15 ♀ imagos, 2♂ imagos, Liujiazi, Gaoleng Town , Fangzheng County, Harbin City , Heilongjiang Province, 45.731443°N, 129.290088°E, ca. 330 m, 21–22.VII.2024, Dewen Gong and Xuhongyi Zheng .

Description: see Kluge (1985).

Distribution: China ( Jilin Province); Russia, Mongolia.

Diagnosis

Mature nymph: Body length 14.0–15.0 mm, wingpads without spots ( Figs 27A, B ). Length ratio of first segment of maxillary palp to galea-lacinia about 1.0: 1.0, inner margin of maxillary palp segment II convex apically ( Fig. 27C ). Posterolateral spines on terga I–IX gradually larger from anterior to posterior, length ratio of posterolateral spine on tergum IX to its tergum = 1.0: 4.0 ( Figs 27D, E ). Each abdominal sternum with inverted U-shaped marking ( Fig. 27B ). Posterior margin of abdominal sternum IX slightly convex ( Fig. 27E ). Dorsal surface of tergum X with stout spine-like setae, lateral margins lack ( Fig. 27F ). Outer margins of dorsal and ventral lamellae of both gills I and II concave, costal rib of dorsal lamella in gill II shorter than half of anterior margin ( Figs 27G, H ). Outer and posterior margins of gill III concave, proximal plate of gill VII well developed ( Figs 27I, J ).

Male imago: Body length 14.0–17.0 mm, wings transparent. Forelegs entirely brown, midlegs and hindlegs entirely light brown ( Figs 28A–C ). Each abdominal sternum with inverted U-shaped marking, posterolateral spines of abdominal segments VIII and IX small ( Figs 28D–G ). Inner margin of basal segment of forceps with projection, length of penis subequal to styliger ( Figs 28D, E ). Dorsal elongation of penis arched and distinctly enlarged apically, outer margin with about 8 small spines, dorsal sclerotized transverse band of penis without expansion, two penis lobes distinctly sclerotized and separated, each tip distinctly bifurcated, ventral side with a translucent membranous projection, inner margin of each penis lobe with 6–9 small spines, outer margin concave in the middle ( Figs 28H, I ).

Female imago: Body length 14.0–16.0 mm, wings transparent. Color pattern similar to male ( Fig. 28J ). Sternum VII extended posteriorly into a triangular lobe. Sternum VIII dark laterally ( Fig. 28K ).

Remarks: S. zhelochovtsevi and S. chankae are very similar, but their male adults can be easily distinguished. In S. zhelochovtsevi , the apical portion of penis lobe elongation is expanded ( Figs 28H, I ), whereas in S. chankae , the basal portion is expanded ( Figs 2H–J ). However, nymphs of these two species are nearly identical and can only be differentiated by a subtle characteristic: inner margin of second segment of maxillary palp in S. zhelochovtsevi is convex apically ( Fig. 27C ), while in S. chankae , it is straight ( Fig. 1C ).

Species comparison

The major morphological differences of nine Chinese Siphlonurus species are listed in the tables 4–7.

Figures

FIGURE 1. Nymph of Siphlonurus chankae: (A) nymph (dorsal view); (B) nymph (ventral view); (C) maxilla; (D) abdominal terga I–IV (dorsal view); (E) abdominal sternum IX of female (ventral view); (F) abdominal sternum IX of male (ventral view); (G) abdominal tergum X (dorsal view); (H) gill I; (I) gill II; (J) gill III; (K) gill VII.

FIGURE 2. Imago of Siphlonurus chankae: (A–J) male structures: (A) male imago (lateral view); (B) forewing; (C) hindwing; (D) genitalia (dorsal view); (E) genitalia (ventral view); (F) abdomen (dorsal view); (G) abdomen (ventral view); (H) penis (dorsal view); (I) penis (ventral view); (J) dorsal elongation of penis (arrow indicating small spines at base of dorsal elongation); (K–L) female structures: (K) abdomen (ventral view); (L) sternum VII.

FIGURE 27. Nymph of Siphlonurus zhelochovtsevi: (A) nymph (dorsal view); (B) nymph (ventral view); (C) maxilla; (D) abdominal terga I–IV (dorsal view); (E) abdominal sternum IX of female (ventral view); (F) abdominal tergum X (dorsal view); (G) gill I; (H) gill II; (I) gill III; (J) gill VII.

FIGURE 28. Imago of Siphlonurus zhelochovtsevi: (A–I) male structures: (A) male imago (lateral view); (B) forewing; (C) hindwing; (D) genitalia (dorsal view); (E) genitalia (ventral view); (F) abdomen (dorsal view); (G) abdomen (ventral view); (H) penis (dorsal view); (I) penis (ventral view); (J) abdomen of female imago (ventral view); (K) sternum VII of female imago.