Try these links

http://decapoda.nhm.org/pdfs/21259/21259.pdf

http://www.travaux.ro/web/pdf/36TMNHNGA-135-146.pdf

http://www.google.fi/books?id=hTg8AAAAIAAJ&lpg=PR7&ots=TQEbfPpzXL&dq=Tanaidacea%20identification%20key&lr&hl=ru&pg=PP1#v=onepage&q=Tanaidacea%20identification%20key&f=false

Do you know what genus you are looking at?  I know that for the deep sea tanaids, the classification keys are redone periodically.  For a good list of literature references, check out http://peracarida.usm.edu/TanaidaceaLit.pdf  Look for the family/genus of interest in the literature to find the latest classifications.

I'm not sure if you mean classification or identification, and also for what region. Blazewicz et al (2012) gives an overview of the diversity of tanaidacea in the World's Ocean and for instance Heard et al (2004) a key to the Florida Tanaidacea. Some other regions have other keys. In Sieg & Winn (1981) you'll find a key to the world genera. See the list given by Adelaide for full references. An up-to-date list of current names and nomenclature is given in www.marinespecies.org

By the way, I have a full PDF version of Holdich & Jones for the British species, so if you need it, I cannot send you this officially :-)

North Atlantic, pictorial key:

http://species-identification.org/species.php?species_group=Crustacea&menuentry=plaatjessleutel&pagenum=443

I have also a the full PDF version of the British Tanaids! ;)

General information. 

http://biostor.org/reference/74124

http://crustacea.nhm.org/glossary/define.html?all=1&noqueryform=1

best regards

although it is dated you can find here (http://www.agu.org/books/ar/v045/AR045.pdf ) a guide for the Arctic and Subarctic. 

best

Supongo que ya habrás recibido ayuda. ¡¡Así que mucho ánimo con tus idenfiticaciones!!

Thank you, with all this I´ve enough information to continue.

Regards

Can any body this finding valid?

not updated in worms?

https://www.researchgate.net/publication/312524699_Description_of_two_new_apseudomorphan_Tanaidacea_Crustacea_Malacostraca_Peracarida_from_the_Kochi_Backwaters_India

Article Description of two new apseudomorphan Tanaidacea (Crustacea:...