Epeorus (Proepeorus) unispinosus Braasch, 1980

Ma, Zhen-Xing, Lei, Zhi-Ming, Li, Wen-Juan & Zhou, Chang-Fa, 2021, A revision of Epeorus (Proepeorus) in China, with descriptions of two new species (Ephemeroptera, Heptageniidae), Journal of Natural History 55 (17 - 18), pp. 1131-1159 : 1136-1137

Epeorus (Proepeorus) unispinosus Braasch, 1980

Figs 1D–F , 6C–D , 15B , 16E

Epeorus sp. Uéno, 1955 , p. 313, Figures 100–110 (nymph).

Epeorus unispinosus Braasch, 1980, p. 62 , Figure 5 . Types: nymph, from Nepal .

Materials examined

14 nymphs, Shaolu Village, Tianmu Mountain, Zhejiang Province, collected by Juan-Yan LUO, Wei ZHANG, Zhen-Xing MA, Ming ZHANG, 14-IV-2017; 70 nymphs, unnamed creek in front of Tian-Mu Hotel, West Tianmu Mountain , Zhejiang Province, collected by Juan-Yan LUO, Wei ZHANG, Zhen-Xing MA, Ming ZHANG, 16-IV-2017; 3 nymphs, Zhoujiatan, West Tianmu Mountain , Zhejiang Province, collected by Juan-Yan LUO, Wei ZHANG, Zhen-Xing MA, Ming ZHANG, 18-IV-2017; 30 nymphs, Huangtukeng Village , Anhui Province, collected by Chang-Fa ZHOU, 1-V-1996; 12 nymphs, Zhongmiao (783m a.s.l.), Chang’an District , Xi’an City, Shaanxi Province, collected by Sheng XU, Zhao XIE, V-2012 .

Diagnosis and remarks

This species can be recognised by the presence of an unpaired median spine on each abdominal tergum from segments II–IX ( Figure 1 (d,f)) and paired distinct pale round maculae on head ( Figure 1 (e)). Adults are unknown.

E. (P.) unispinosus was originally described by Uéno (1955) based on an incomplete nymphal specimen (without gill I) collected in Nepal as Epeorus sp. Braasch (1980) proposed the name Epeorus unispinosus to this species but provide no new information about it. Our materials are complete, the structures of gill lamellae (slightly expanded gill I and unfolded gill VII, Figure 6 (d)) show that it is a member of the subgenus Proepeorus or Epeorus s.str. Since the nymphal characteristics of E. (P.) unispinosus and Epeorus (Proepeorus) gibbus sp. nov. are very similar (see remarks of E. (P.) gibbus sp. nov. below), we temporarily regard E. (P.) unispinosus as a Proepeorus species.

Distribution

China (Zhejiang, Anhui, Shaanxi), Nepal .

Figures

Figure 1. Nymph of Epeorus spp.: (a–c) Epeorus (Proepeorus) nipponicus: (a) Nymphal habitus, (b) Head capsule, (c) Abdominal terga VII–X; D–F: Epeorus (Proepeorus) unispinosus: (d) Nymphal habitus, (e) Head capsule, (f) Abdominal terga VII–X.

Figure 5. Nymphal habitus and abdominal terga of Epeorus (Propeorus) spp.: A–B: E. (P.) aculeatus, (a) Nymphal habitus, (b) Abdominal terga VII–X; C–D: E. (P.) bispinosus, (c) Nymphal habitus, (d) Abdominal terga VII–X; (e, f): E. (P.) bifurcatus, (e) Nymphal habitus, (f) Abdominal terga VII–X; (g, h) E. (P.) rhithralis, (g) Nymphal habitus, (h) Abdominal terga VII–X.

Figure 6. Nymphal structures of Epeorus spp.: (a–c) Labrum, (a) Epeorus (Epeorus) melli, (b) Epeorus (Propeorus) nipponicus, (c) E. (P.) unispinosus; (d, e) Gill I, (d) E. (P.) unispinosus, (e) E. (P.) bifurcatus; (f–h) Posterior margin of tergum VII, (f) E. (P.) bispinosus, (g) E. (P.) rhithralis; (h) E. (P.) bifurcatus.

Figure 15. Mouthparts of Epeorus (Proepeorus) spp.: (a–f) labrum, (a) E. (P.) nipponicus; (b) E. (P.) unispinosus; (c) E. (P.) bifurcatus; (d) E. (P.) aculeatus; (e) E. (P.) rhithralis; (f) E. (P.) bispinosus; (g–i) base of apical tooth complex of maxilla, (g) E. (P.) gibbus sp. nov.; (h) E. (P.) falcatus sp. nov.; (i) E. (P.) nipponicus.

Figure 16. Incisors of left mandible in ventral view: (a) Epeorus (Epeorus) melli; (b) Epeorus nguyeni; (c) Epeorus (Proepeorus) nipponicus; (d) Epeorus (Belovius) pellucidus; (e) Epeorus (Proepeorus) unispinosus; (f) Epeorus (Proepeorus) gibbus sp. nov.; (g) Epeorus (Iron) alexantri; (h) Epeorus (Proepeorus) falcatus sp. nov.; (i) Epeorus (Proepeorus) aculeatus; (j) Epeorus (Proepeorus) bifurcatus; (k) Epeorus (Proepeorus) bispinosus; (l) Epeorus (Proepeorus) rhithralis.