Ra
- Rabilimis
- Racovitzanus
- Raddaus
- Radimella
- Raillietiella
- Rak
- Rakiroa
- Rakiroidae
- Ramellogammarus
- Ramosiseta
- Randallia
- Ranilia
- Ranina
- Raninidae
- Raninoidea
- Raninoides
- Raoulia
- Raoulserenea
- Rapaniscus
- Rata
- Ratania
- Rataniidae
- Rataniidae
- Rathbunamon
- Rathbunaria
- Raumahara
- Raylilia
- Raymanninus
- Raymunida
- Raytheres
Re
- Rectarcturidae
- Rectarcturus
- Rectisura
- Rectopalicus
- Redekea
- Reductoniscus
- Reductosoma
- Regabellator
- Regalia
- Reighardiidae
- Reighardiidae
- Remanea
- Remasellus
- Remexudes
- Remiarctus
- Remipedia
- Remipedia
- Renocila
- Resupinus
- Retromysis
- Retropluma
- Retroplumidae
- Retroplumoidea
Rh
- Rhabdocheirus
- Rhabdochiridae
- Rhabdoniscus
- Rhabdonotus
- Rhabdopus
- Rhabdosoma
- Rhachotropis
- Rhacura
- Rhadinocythere
- Rhadinoplax
- Rhamphochela
- Rheocyclops
- Rhepoxynius
- Rhiganthura
- Rhincalanidae
- Rhincalanidae
- Rhincalanus
- Rhinobranchipus
- Rhinocarcinus
- Rhinoecetes
- Rhinolambrus
- Rhinolithodes
- Rhinospinosa
- Rhiothra
- Rhithropanopeus
- Rhizopa
- Rhizopoides
- Rhizorhina
- Rhizothricidae
- Rhizothricidae
- Rhizothrix
- Rhodesillo
- Rhodochirus
- Rhodopioniscus
- Rhopalione
- Rhopalophthalmus
- Rhynchochondria
- Rhynchochydorus
- Rhynchocinetes
- Rhynchocinetidae
- Rhyncholagena
- Rhynchomolgidae
- Rhynchomolgidae
- Rhynchotalona
- Rhynchothalestris
- Rhynocrangon
- Rhynohalicella
- Rhyscotidae
- Rhyscotoides
- Rhyscotus
Ri
- Richardina
- Richardsoniscus
- Richerellus
- Ridgewayia
- Ridgewayiidae
- Ridgewayiidae
- Riggia
- Rildardanus
- Rimakoroga
- Rimapenaeus
- Rimitantulus
- Ringaringa
Rissoides Manning & Lewinsohn, 1982
- Rissoides africanus (Manning, 1974)
- Rissoides barnardi (Manning, 1975)
- Rissoides calypso (Manning, 1974)
- Rissoides desmaresti (Risso, 1816)
- Rissoides pallidus (Giesbrecht, 1910)
Crustacea → Malacostraca → Stomatopoda → Squilloidea → Squillidae
- Rizalthus
Ro
- Robertgurneya
- Robertsella
- Robertsonia
- Robertsonites
- Robustaurila
- Robustochelia
- Robustunguis
- Rochinia
- Rocinela
- Rodoniscus
- Rodriguezia
- Rodriguezus
- Rolandoniscus
- Romaleon
- Rophidopus
Roramoscia Leistikow, 2001
- Roramoscia roraimae (Van Name, 1936)
Crustacea → Malacostraca → Isopoda → Oniscidea → Philosciidae
- Rossopsyllus
- Rostratoverruca
- Rostrobagatus
- Rostroculodes
- Rostromysis
- Rostrophiloscia
- Rotomelita
- Rotundovaldivia
- Rotundracythere
- Roundstonia
- Rouxana
- Rozinante
Ru
- Rudilemboides
- Rufuta
- Rugocythereis
- Rugojoeropsis
- Runanga
- Ruppellioides
- Rutiderma
- Rutidermatidae
- Rutidermatidae
Ry
- Ryphila
- Ryukyua
- Ryukyum