Vietnamella, Tshernova, 1972

Luo, Yanping, Jiang, Jian, Wang, Lili, Shu, Zufei & Tong, Xiaoli, 2020, Vietnamella chebalingensis, a new species of the family Vietnamellidae (Ephemeroptera) from China based on morphological and molecular data, Zootaxa 4868 (2), pp. 208-220 : 215-216

Key to known larvae of Vietnamella

(Excluding V. ornata which is known only from the subimago)

1. Outer pair of cephalic projections with serration............................................................. 2

- Outer pair of cephalic projections smooth without serration.................................................... 3

2 Length ratio from basal to apical segments of maxillary palp = 1:0.9:0.7; pairs of projections on posterior margins of abdominal tergites I–X....................................................................... Vietnamella sp. A [ India]

- Length ratio from basal to apical segments of maxillary palp = 1.3:1:1.1; pairs of projections on posterior margins of abdominal tergites II–VI and VIII–X, tergite VII with a single projection............................ Vietnamella sp. B [ Thailand]

3 Body, especially legs usually with mottled color pattern....................................................... 4

- Body and legs usually unicolor.......................................................................... 6

4 Length ratio of outer cephalic projection to the inner about 2:1; length ratio from basal to apical segments of maxillary palp =1:1.3:1; pairs of projections on posterior margins of abdominal tergites I–VI and VIII–X, tergite VII with only a single posterior projection.................................................................... V. chebalingensis sp. nov.

- Length ratio of outer cephalic projection to the inner at least 3:1; pairs of projections on posterior margins of abdominal tergites I–X................................................................................................ 5

5 Length ratio from basal to apical segments of maxillary palp =1:1.3:1; transverse ridge of fore femur with spatulate setae............................................................................................... V. nanensis

- Length ratio from basal to apical segments of maxillary palp =1.3:1.2:1; transverse ridge of fore femur with small rounded setae...................................................................................... V. maculosa

6 Length of basal segment of maxillary palp nearly equal to length of the second segment, posterior margin of tergite X with a pair of weakly developed projections................................................................ V. thani

- Length of basal segment of maxillary palp shorter than length of the second segment, posterior margin of tergite X with a pair of apparent pointed projections.................................................................. V. sinensis