Revision of type and non-type material assigned to the genus Orthocladius by Goetghebuer (1940 - 1950), deposited in the Royal Belgian Institute of Natural Sciences (Diptera: Chironomidae) Author Magoga, Giulia ) &) &) Università degli Studi di Milano, Dipartimento di Scienze Agrarie e Ambientali (DISAA), via Celoria 2, I 20133, Milano, Italia; e-mails: giulia. magoga @ unimi. it; matteo. montagna @ unimi. it Author Montagna, Matteo ) &) &) Università degli Studi di Milano, Dipartimento di Scienze Agrarie e Ambientali (DISAA), via Celoria 2, I 20133, Milano, Italia; e-mails: giulia. magoga @ unimi. it; matteo. montagna @ unimi. it Author Marziali, Laura ) &) Water Research Institute, National Research Council (IRSA-CNR), Via del Mulino 19, I 20861 Brugherio (MB), Italy; e-mail: marziali @ irsa. cnr. it Author Rossaro, Bruno ) &) Università degli Studi di Milano, Dipartimento di Scienze per gli Alimenti, la Nutrizione e l’Ambiente (DeFENS), Via Celoria 2, I 20133 Milan, Italy; e-mail: bruno. rossaro @ unimi. it Author Disaa text Acta Entomologica Musei Nationalis Pragae 2017 Acta. Ent. Mus. Natl. Pragae 2017-12-31 57 2 723 749 http://dx.doi.org/10.1515/aemnp-2017-0097 journal article 10.1515/aemnp-2017-0097 0374-1036 5318416 638421F2-985E-43CC-8438-E871F96B1DB8 Diamesa cinerella Meigen, 1835 Diamesa cinerella Meigen, 1835 in GISTL (1835: 66) . Diamesa waltlii Meigen, 1838: 13 . Material examined. 2 specimens in isinglass, now mounted on slides: one ♁ and one ♀ labelled: ‘ D. waltli Mg. // Hockai Hautes Fagnes, 11. VI . 1912 // R .I.SC.N.B. 18.073 / Coll. et det. M. Goetghebuer’. Comments. The male fits well with the species description of D. cinerella . At this time, it is impossible to confirm species identity of the female. SERRA- TOSIO (1971: 222) described a female from a copula with a male, and WILLASSEN & SERRA- TOSIO (1988: 92) even described the female lectotype . Despite these descriptions the females within the D. cinerella group cannot be separated at present.