Species: Dineutus australis (Fabricius, 1775)
Classification
Phylum: Arthropoda
 Class: Insecta
  Order: Coleoptera
   Family: Gyrinidae
    Genus: Dineutus

Morphology:
Adult:
 - Dineutus australis is closest to D. unidentatus but can be distinguished by both sexes of D. australis have the oval body form and larger size (male: size 7.6–8.2 mm; female: size 8.1–8.2 mm) than that D. unidentatus, and male elytral apices with weak epipleural spines. The median lobe of D. australis aedeagus is very narrow and without a constricted apex in dorsal view. The females of both species can be distinguished by D. australis has the elytral apices lacking epipleural spines and broader gonocoxae with the apex nearly straight.


Figure
Dorsal habitus of Dineutus australis male (Photo: Benjamart Suksai).


Habitat: - In Thailand, D. australis was found on the water surface of ponds in the forest where it occurred among aquatic plants in shallow water. Additionally, it was found in shallow, stagnant streams.

Distribution:
 - Chiang Mai Province: Doi Inthanon Nattional Park.
- Khon Kaen Province: Chum Pae District.
- Nakhon Ratchasima Province: Sakaerat Environmental Research Station.
- Phang Nga Province: Takua Pa District.
- Prachuap Khiri Khan Province: Hua Hin District.
- Prachuap Khiri Khan Province: Thap Sakae District.

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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