Nato a Firenze il 12 Aprile 1938, laureato in Scienze agrarie e forestali presso l’Università di Firenze. Ha svolto tutta la sua carriera universitaria presso l’Università di Siena. E’ stato professore ordinario di Zoologia dal 1975 e Preside della Facoltà di Scienze M.F.N. dal 1980/1 al 1998/99. E’stato Direttore del Dipartimento di Biologia Evolutiva e del Dottorato di Ricerca in Biologia Evolutiva. E’stato Presidente dell’Unione Zoologica Italiana dal 1998 al 2001 e Presidente dell’Accademia Nazionale Italiana di Entomologia dal 2010 al 2019.
Si è dedicato alla studio sistematico dei Collemboli ed alla Microscopia elettronica dal 1965, svolgendo ricerche ultrastrutturali su strutture ed organi di insetti ed in particolare su quelli della riproduzione e gli spermatozoi. Ha pubblicato oltre 600 lavori, molti dei quali su riviste qualificate. Ha numerose collaborazioni. E’nel Comitato editoriale di riviste straniere e serve come revisore per molte altre.
E’ professore Emerito dell’Università di Siena dal 2012.
La Facoltà di Scienze M.F.N. nel 2010, gli ha conferito la medaglia d’oro per il proficuo lavoro svolto a favore della Facoltà.
L’Accademia Nazionale di Entomologia nel 2019 lo ha onorato di una targa ricordo per la sua lunga attività di Presidente.

R. Dallai, P.P. Fanciulli. F. Frati, 2000- Aberrant spermatogenesis and the peculiar mechanism of sex determination in Symphypleonan Collemboa (Insecta).. The Journal of Heredity, 91, 351-358.

R .Dallai, P. Lupetti, C. Mencarelli, 2006- Unusual axonemes of hexapod spermatozoa. International Review of Cytology, 254, 45-99.

R. Dallai, M. Gottardo, D. Mercati, R. Machida, Y. Mashimo, Y. Matsumura, R.G. Beutel, 2013- Divergent mating patterns and unique mode of external sperm transfer in Zoraptera: an enigmatic group of pterygote insects. Naturwissenschaften, 100, 581-594.

R. Dallai, 2014- Overview on spermatogenesis and sperm structure of Hexapoda. Arthropod Structure and Development, 43, 257-290.

R. Dallai, M. Gottardo, R.G. Beutel, 2016- Structure and Evolution of Insect Sperm : Interpretation in the Age of Phylogenomics. Annual Review of Entomology, 61, 1-23.

Born in Florence on April 12.1938, he graduated in Agriculture Sciences at the University of Florence. All his university career was developed at the University of Siena. He was full Professor of Zoology, since 1975 and Dean of the Faculty of Sciences from 1980/81 to 1998/99. He was chair of the Department of Evolutionary Biology and directed the PhD school of Evolutionary Biology. He was President of the Italian Union of Zoology (UZI) (1998-2001) and of the National Italian Academy of Entomology (2010-2019).
His main scientific activities dealt with the Systematics of Collembola and the Electron microscopy of tissues and organs of Insects, reproductive systems and spermatozoa in particular.
He published more than 600 works, many on reputed international Journals. He has numerous collaborations, is in the Editorial board of several Journals and serves as reviewer for many others.
He is Emeritus Professor of the University of Siena, since 2012.
The Faculty of Sciences honored him with a gold medal for his outstanding Dean activity that greatly contributed to the development of the Faculty (2010).
The National Academy of Entomology honored him with a recognition plate for his long
activity for the promotion of the Institution (2019)

R. Dallai, P.P. Fanciulli. F. Frati, 2000- Aberrant spermatogenesis and the peculiar mechanism of sex determination in Symphypleonan Collemboa (Insecta).. The Journal of Heredity, 91, 351-358.

R .Dallai, P. Lupetti, C. Mencarelli, 2006- Unusual axonemes of hexapod spermatozoa. International Review of Cytology, 254, 45-99.

R. Dallai, M. Gottardo, D. Mercati, R. Machida, Y. Mashimo, Y. Matsumura, R.G.
Beutel, 2013- Divergent mating patterns and unique mode of external sperm transfer in Zoraptera: an enigmatic group of pterygote insects. Naturwissenschaften, 100, 581-594.

R. Dallai, 2014- Overview on spermatogenesis and sperm structure of Hexapoda. Arthropod Structure and Development, 43, 257-290.

R. Dallai, M. Gottardo, R.G. Beutel, 2016- Structure and Evolution of Insect Sperm : Interpretation in the Age of Phylogenomics. Annual Review of Entomology, 61, 1-23.