Epeorus (Proepeorus) rhithralis 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 : 1142

Epeorus (Proepeorus) rhithralis Braasch, 1980

Figs 5G–H , 6G , 15E , 16L

Epeorus rhithralis Braasch, 1980, p. 60 , Figure 4 (b–l) (nymph). Types: nymph, from

Nepal.

Materials examined

20 nymphs, Daping Village (103°5′44.32″N, 22°55′59.6″E), Jinping County, Yunnan Province, collected by Zhen-Xing MA, 20-X-2020; 8 nymphs, Wola Village (102°51′ 31.2588″N, 23°3′40.81″E), Jinping County , Yunnan Province, collected by Zhen-Xing MA, 21-X-2020 .

Diagnosis and remarks

E. (P.) rhithralis is differentiated from other congeners by the paired tubercles on terga ( Figure 5 (g,h)), pointed denticles on posterior margin of terga ( Figure 6 (g)) and colouration pattern of femur ( Figure 5 (g)). This species most resembles Epeorus inthanonensis Braasch & Boonsoong, 2010 by having similar paired tubercles and pointed denticles on posterior margin of abdominal terga. As mentioned in the research of Braasch and Boonsoong (2010), E. (P.) rhithralis can be separated from E. inthanonensis according to different size of gill I: E. inthanonensis has smaller gill I than gill II–VI, while E. (P.) rhithralis with gill I larger than all other gills. However, according to figures from original description of E. (P.) rhithralis ( Braasch, 1980: Figure 4 (j–l)), its gill I is slightly expanded anteriorly and obvious smaller than gill III. Considering that the colouration pattern of the femur of specimens in China is same as E. (P.) rhithralis (with one median spot surrounded by irregular marking, see Braasch 1980: Figure 4 (g)) but significantly different from that of E. inthanonensis (only with one median spot, see Braasch and Boonsoong 2010: fig. 75), this species in China is temporarily designated as E. (P.) rhithralis . Adults are unknown.

Distribution

China (Yunnan), Nepal.

Figures

Figure 4. Nymph of Epeorus (Proepeorus) gibbus sp. nov.: (a) Head capsule; (b) Labrum (ventral view on left, dorsal view on right); (c) Right mandible; (d) Left mandible; (e) Glossae of labium (dorsal view on left, ventral view on right); (f) Femoral setae; (g) Claw; (h) Abdominal tergum VII (dorsum); (i) Posterior margin of tergum VII (vertical line is midline of tergum); (j) Gill I; (k) Gill II; (l) Gill VII.

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.