Species: Rhithrogeniella tonkinensis Soldán & Braasch, 1986
Classification
Phylum: Arthropoda
 Class: Insecta
  Order: Ephemeroptera
   Family: Heptageniidae
    Genus: Rhithrogeniella

Morphology:
Larva:
 The larvae of R. tonkinensis can be distinguished from those of other genera of Heptageniidae by the following combination of characters: the head is approximately as broad as the pronotum, without a median emargination and marginal bristles and by the presence of interfacing setae on the caudal filaments. The latter are provided at rings with rather stout spines regularly alternating with fine setae (Boonsoong and Braasch, 2013).


Figure


Larva of Rhithrogeniella tonkinensis
Habitat: Larvae of R. tonkinensis occur in relative deep waters (30-40 cm) with slow currents and smaller stones or coarse sand on the bottom. Larvae are good swimmers, but prefer to remain attached to the stone surface rather than swimming (Soldan and Braasch 1986).

Distribution:
 - Chiang Mai Province
 - Chaiyaphum Province

Work cited:
 - Boonsoong, B. and Braasch, D. 2013. Heptageniidae (Insecta, Ephemeroptera) of Thailand. ZooKeys 272: 61–93.
 - Soldan, T. and Braasch, D. 1986. Rhithrogeniella tonkinensis sp.n. (Ephemeroptera, Heptageniidae) from Vietnam, with description of the larval stages and biology of the genus. Acta entomologica Bohemoslovaca 83: 202–212.

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