Subgenus
Tetrada (Tetrada) Neckaja, 1958
Selection of related publications
Meidla, T. 1996. Late Ordovician Ostracodes of Estonia. Fossilia Baltica 2. pp. 1-222.  Tartu University Press. 
Meidla, T. 1986. Neue Ostrakoden aus dem Ordovizium des Baltikums.  Eesti NSV Teaduste Akadeemia Toimetised. Geoloogia / Известия Академии наук Эстонской ССР. Геология   35,   1,   10-19. DOI:10.3176/geol.1986.1.02
Sarv, L. 1959. Ordovician ostracodes in the Estonian S.S.R..  ENSV TA Geoloogia Instituudi Uurimused   IV,      1-210.
Neckaja, A. I. 1953. Tetradellidy ordovika Pribaltiki i ih stratigraficheskoe znachenie.  Trudy Vsesoûznogo Naučno-Issledovatel'skogo Geologo-Razvedočnogo Instituta (VNIGRI)         309-363.  Gostoptehizdat. 
List of species
1. Tetrada (Tetrada) grandis (Sarv, 1959) | Keila Stage
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Classification
| Organism group | Biota | 
| Kingdom | Animalia | 
| Phylum | Arthropoda | 
| Subphylum | Crustacea | 
| Superclass | Oligostraca | 
| Class | Ostracoda | 
| Subclass | Podocopa | 
| Order | Palaeocopida | 
| Suborder | Beyrichicopina | 
| Palaeocopa | |
| Family | Ctenonotellidae | 
| Genus | Tetrada | 
| Subgenus | (Neotsitrella) | 
| (Perplana) | |
| (Tallinnopsis) | |
| (Tetrada) | |
| Species | grandis | 
| harpa | |
| krausei | |
| memorabilis | |
| neckajae | |
| ovalis | |
| pseudoiewica | |
| variabilis | |
| hibyi | |
| ventroconcava | |
| Subspecies | troppenzorum |