Epeorus (Proepeorus) bifurcatus Braasch & Soldán, 1979

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 : 1143

Epeorus (Proepeorus) bifurcatus Braasch & Soldán, 1979

Figs 5E–F , 6E, H , 15C , 16J

Epeorus bifurcatus Braasch & Soldán, 1979, p. 270 , Figures 15 –22 (nymph). Types: nymph, from Vietnam .

Epeorus bifurcatus: Nguyen and Bae 2004, p. 21 (nymph); Braasch and Boonsoong 2010, p. 23 .

Materials examined

2 nymphs, Pingshan County, Yibin City, Sichuan Province, collected by Bei-Xin WANG, 19- XI-2019; 20 nymphs, Baijin Town, Huishui County , Guizhou Province, collected by Chang- Fa ZHOU, 11-IX-2000; 30 nymphs, Dali Ancient City, Yunnan Province, collected by Jia- Chang QIN, Peng LI, 25-VII-2009 .

Diagnosis and remarks

E. (P.) bifurcatus is recognised among Asian Epeorus species by a pair of small submedian spines on terga II–IX ( Figure 5 (e,f)), a row of blunt denticles along posterior margin of terga and triangular gill I ( Figure 6 (e,h)). This species most resembles E. (P.) bispinosus in the paired submedian spines on terga and triangular gill I, but E. (P.) bispinosus can be distinguished from it by the acute denticles along the posterior margins of terga. Shape of submedian spines of E. (P.) bifurcatus are variable: more developed and sharper in some individual. Adults are unknown.

Distribution

China (Yunnan, Guizhou, Sichuan), Vietnam, Thailand.

Figures

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.