Species: Gyrinus smaragdinus Régimbart, 1891
Classification
Phylum: Arthropoda
 Class: Insecta
  Order: Coleoptera
   Family: Gyrinidae
    Genus: Gyrinus

Morphology:
Adult:
 - Two species of Gyrinus recorded from Thailand are Gyrinus smaragdinus and G. sericeolimbatus. Both species can be distinguished by G. smaragdinus has iridescent appearance and strongly sulcate lateral elytral striae.


Figure
Dorsal habitus of Gyrinus smaragdinus male (Photo: Benjamart Suksai).


Habitat: - G. smaragdinus was found most often on stagnant water of mountain streams and ponds at high elevation (700 to 1600 m a.s.l.). Only a few specimens were found in a stream at a low elevation (270 m a.s.l.).

Distribution:
 - Chiang Mai Province: Doi Inthanon National Park.
- Chiang Mai Province: Doi Suthep National Park.
- Chiang Mai Province: Pond at Ban Buak Thoei, Mae Rim District.
- Kanchanaburi Province: Thong Pha Phum National Park.
- Loei Province: Phu Hin Rongkla National Park.
- Loei Province: Phu Kradueng National Park.
- Nan Province: Doi Phuka National Park.
- Nan Province: Khun Sathan National Park.
- Phitsanulok Province: Phu Hin Rongkla National Park.
- Phitsanulok Province: Thung Salaeng Luang National Park.

Work cited:
 - Suksai, B., Gustafson, G.T., Sites, R.W. and Sangpradub, N. 2021. The Gyrinidae (Coleoptera) fauna of Thailand: Key to tribes and genera, with new records and keys to species of Dineutini and Gyrinini. Zootaxa 5071(1): 097–117.

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