I would like to ask if there is there an appropriate taxonomical reference book of fresh water benthic macroinvertebrates, especially based on the Asian region as many of the books currently used are from Europe and Western regions.
I am not sure if there is any "monography", but for invertebrates of Southeast Asia exist a Conference Overview: http://www.jlimnol.it/index.php/jlimnol/issue/view/44. Maybe you find some colleagues here: https://www.iucn.org/about/work/programmes/species/who_we_are/ssc_specialist_groups_and_red_list_authorities_directory/invertebrates/
Thank you, the question of "is it appropiate to identify invertebrates from south east asia base on work done from other continent" always plays in my mind during identification process.
Some genera of freshwater organims are living all over the and for them is possible to use any key you like to identify to family or genere level. But some times it useful to have identifing key for different regions.
I have found this key for invertebrate from Mekcong river my be it could help you.
for freshwater mollusks the first place to begin is with
Brandt, R.1974. the non-marine aquatic Mollusca of Thailand Archive fur Molluskenkunde 105:1-423.
Ðặng, N.T., Thai, T.B. and Phạm, V.M. 1980. Ðịnh loại động vật không xương sống nước ngọt Bắc Việt Nam. Nhà Xuất bản Khoa học và Kỹ thuật, Ha Noi,Viet Nam. 573 pp. [on the freshwater invertebrates of North Vietnam]
He Jing and Zhuang Zimin. 2013. The Freshwater Bivalves of China. ConchBooks. Bahnhofstr. 117 D-55296 Harxheim, Germany.198 pages.
and there is a recent volume on the freshwater mussels of Japan.
As starting point I would recommend "Freshwater Invertebrates of the Malaysian Region" by C. M. Yule & H. S. Yong, 01/2004; Publisher: Academy of Sciences Malaysia, ISBN: 983-41936-0-2
Dependong on the group you are looking at, for the specific families or genera it's also worth searching the "Raffles Bulletin of Zoology" articles.
For higher level identification (eg. to Family level) you can generally use more generic references such as those indicated by others. For lower levels (eg. generic or species) there is unlikey to be any one reference that will cover all taxonomic groups. It would be best to use taxon specific ones for your area or region (eg. those for Penisula Malaysia, if that's your area of interest).
The material which I found very helpful is by "Dudgeon, D. (1999). Tropical Asian streams: zoo benthos, ecology and conservation. Hongkong: Hong Kong University Press".
Moreover, survey for materials till you not get any answer whether right or wrong and then for final answer send your sample to any specialist. Search till you don't get confused as it may make you more confused and less confident.
That what i afraid of... Thanks for the advice. Currently i work with other colleague with similar background rather solely doing identification process... Argument do work. Thank you