Rotula: a small round segment sometimes present between the joints of antenna; and palpi: = torquillus.
Rotule: the trochantine.
Rotundate: rounded: in the form of a circle or segment of a circle: without angles: said of margins when they pass gradually into each other and do not form an angle at their point of junction.
Royal jelly: the food supplied to bee larva that develop into queens.
Royal pairs or Royalties: the sexually active males and females of social insects.
Ruben: red, approaching carmine [alizar crimson].
Rubescent: reddish or becoming red.
Rubiginose: a rusty red [dragon's blood, but brighter].
Rubinous: ruby red: like the eye of a house fly.
Rudiment -any: the beginning of any structure or part before it has developed.