Guérin-Méneville, 1836
Head produced into single short rostrum (Primno brevidens 1, Primno macropa 1). ANT I of female longer than head, ANT II reduced to a tubercle. Pereonites I and II separate. P III, IV and VI simple. ART 5 of P V enlarged, anterior margin of ART dentate, with several long teeth separated by groups of short teeth (Primno brevidens 2, Primno latreillei 1, Primno macropa 2). P VII with all ART. Telson small.
Four species, 3 in the South Atlantic:
Primno brevidens Bowman, 1978
Primno latreillei Stebbing, 1888
Primno macropa Guérin-Méneville, 1836
Species of genus differ almost only in armament of ART 5 of P V (see key) and in length of body.