Sars, 1902
Females
Total length 1.3-9.8 mm. Body slender, Pr oval, Ce and Pd1 separated, Pd4 and 5 fused, posterolateral corners rounded. Ce rounded anteriorly, sometimes with anterolateral horns; rostral filaments slender. Ur elongate, of 4 somites. CR symmetrical, relatively long, with 7 setae. A1 symmetrical, 25-segmented. A2 Basis with 1-2 outer edge setae; Exp and Enp separated from Basis; Enp 2-segmented, Enp1 with 2 setae at about midlength, Enp2 with 7 inner setae medially and 6 or 7 setae terminally; Exp 8-segmented. Md gnathobase with 9 sharp teeth; Enp 2-segmented, Enp1 with 4 setae, Enp2 with 8 setae terminally; Exp1-4 with 1 seta each, Exp5 carrying 2 setae. Mx1 Li1 with 13 spines and setae; Li2 with 3 setae ; Li3 with 3 setae, Li4 with 4 setae; Enp 1-segmented, with 4+5 setae; Exp large, with 11 setae; Le1 with 5-6 setae. Mx2 Li1 and 2 with 3-4, 3 setae; Li3 and 4 with 3 setae each; Li5 with 3 setae one of them stouter than other 2, spinulose; Enp with 7 setae. Mxp Coxa with 3-5 setae; Basis with patches of setules or spinules and 3 setae medially; Enp 6-segmented, Enp1 almost fully incorporated into Basis with 2 setae, Enp2-5 with 2 setae each, segment 6 with 4 setae the outermost 3 of which are reduced. P1-4 distinctly 3-segmented, Enp segments of P1 and 5 2-3-segmented, inner distal setae on Basis of P1 inserted on conical projection.
Spine and seta formula: Spine and seta Lucicutiidae.
P5 natatory, symmetrical, very similar to other swimming legs; inner edge seta on Exp2 modified into long slender spine articulated with its segment.
Males
Total length 1.2-8.6 mm. Body similar to female, but Ur of 5 somites. Left A1 geniculate, 21-segmented. Mouthparts and P1-4 similar to female. P5 with 3-segmented Enp and Exp on left, Basis usually modified with one or more inner extensions which may bear spines; Exp and Enp usually 2-segmented on right, last Exp segment recurved; Coxa on either side may sometimes be modified with extensions.
There is only one genus Lucicutia Giesbrecht, 1898 in this family which was reviewed by Hülsemann (1966).