Rhithrogena (Tumungula) siamensis Braasch & Boonsoong, 2009

Boonsoong, Boonsatien & Braasch, Dietrich, 2013, Heptageniidae (Insecta, Ephemeroptera) of Thailand, ZooKeys 272, pp. 61-93 : 69-70

Rhithrogena (Tumungula) siamensis Braasch & Boonsoong, 2009 Figs 2A5 C–D

Rhithrogena (Tumungula) siamensis Braasch & Boonsoong, 2009: 39-43, Figs 32-47. (orig.)

Larva.

Braasch and Boonsoong 2009: 39-43, Figs 32-47.

Adult.

Braasch and Boonsoong 2009: 38-39, M, Figs 19-30; F, Fig. 31.

Eggs. General shape ovoid. One of the poles terminates with large knob-terminated coiled threads (KCTs) (Fig. 5C), the whole chorion is covered with uniform granules and scattered with small loose KCTs, with a large micropyle on the equatorial plane (Fig. 5D).

Distribution.

Mae Hong Son province, Chiang Mai province, Chiang Rai province, Loei province.

Diagnosis.

The larva of Rhithrogena siamensis resembles Rhithrogena (Tumungula) unica Zhou & Peters, 2004 but differs in mouthparts structure and gill 1, with Rhithrogena siamensis being pointed-crenulate and having longer plica which are more bluntly rounded, whereas that of Rhithrogena (Tumungula) unica has a few angular crenulations and a shorter, more strongly rounded plica.

Habitat and biology.

Rhithrogena siamensis larvae cling to rock surfaces in medium- to fast-flowing water. Collections over most of the year revealed that the flight season at altitudes of 600 m was mainly during March/April, just before the beginning of the monsoon rains in May.

Remarks.

Only one species of Rhithrogena was identified in our study as being distributed thoughout Thailand. They live in a rapid current of stream.