Rhithrogena ampla Kang & Yang, 1994

Rhithrogena ampla Kang & Yang, 1994, nymphs and eggs

Material. 2 nymphs paratypes, one entirely mounted on microscopic slide: Taiwan, Tzuenchiao, Hsiulin, Hualin Hsien, 2010 m, 04.IV.1991, C.K. Kang leg [MZL]

Supplementary description. Kang & Yang (1994) mentioned that this species is very close to Rh. parva and hardly distinguishable in the larval stage, the discriminating features being the chorionic structure of the eggs and the altitudinal zonation.

I can confirm the assertion that both species are very similar. However, the setation of the mandibles (Figs 35–36) of Rh. ampla continues almost up to the mola (not reaching the middle of the distance to the mola in Rh. parva), and the posterior margin of abdominal tergites bear irregular teeth similar to those of Rh. sumatrana (Fig. 26).

All other characters examined are similar between Rh. parva and Rh. ampla .

Taxonomic outcomes. The reassignment of Ecdyonurus sumatranus to the genus Rhithrogena has important taxonomic consequences.

First, the nymph described as either Ecdyonurus sumatranus (listed by some as Ecdyonuroides or Thalerosphyrus), belongs to Ecdyonurinae and cannot be the nymph of Rhithrogena sumatrana . To my knowledge, there are no valid junior synonyms for this taxon, and consequently, a new name should be provided.