Sars, 1902
Females
Ce and Pd1 fused or separate, Pd4 and 5 fused or separate, posterior corners rounded or pointed, symmetrical or asymmetrical, may be prolonged into lobes (Undinella). R is bifurcate plate with filaments (Parundinella, Undinella), or plate with or without filaments. Ur of 4 somites, Gns symmetrical or asymmetrical. A1 23-24-segmented, segments 8-9 fused. A2 Exp incompletely 7-segmented (6-segmented in Rythabis); slightly more than twice length of Enp (Tharybis, Undinella), about twice length of Enp (Parundinella spinodenticulata), Basis and Enp1 with 2 setae; Exp1 and Exp2 without setae (Exp2 with 2 setae in some species of Parundinella). Md with strong gnathobase. Mx1 Li1 large and extending beyond remainder of appendage (Tharybis), or not enlarged (Undinella), with 11-14 terminal spines (9 terminal and 4 posterior setae in the type species Tharybis macrophthalma); Li2 with 2-3 setae; Li3 with 3-4 setae; Li4 usually with 3-4 setae; Enp usually with 6-7 setae; Exp with 2 setae (Undinella), or 3-7 setae (5 setae in Tharybis macrophthalma); Le1 usually with 6-7 setae (with 9 setae in Tharybis macrophthalma). Rythabis strongly deviates in setation of Mx1. Mx2 Li1 with 4 setae; Li2-Li5 with 3, 3, 3 and 4; sensory setae may be present on Li5 (Parundinella, Rythabis); Enp (terminal part) of limb in type species with 3 worm-like plus 4 brush-like setae plus 1 sclerotized setae (Tharybis macrophthalma), or with 3 worm-like and 5-6 brush-like sensory setae (there are deviations in composition and number of sensory setae in Tharybidae; correct setal formula for family can not be given till revision of all its species). Mxp Coxa with 1 proximal seta, then with groups of 2, 3 and 3 sclerotized setae (Tharybis macrophthalma) from proximal to distal, in other species some setae may be replaced by sensory setae; Basis with medial row of denticles followed by 3 setae; Enp1-Enp5 with 4, 4, 3, 4 and 4 setae respectively (Tharybis macrophtalma). P1 Enp with well-developed outer lobe. Posterior surfaces of P2-P4 may be slightly spinulose.
Spine and seta formula: Spine and seta Tharybidae.
P5 present, uniramous, consists of basal segment plus one segment (Parundinella); or 3-segmented (Undinella, Tharybis, Rythabis), terminal segment with 1 or 2 terminal spines as well as articulated inner edge spine (Tharybis), or with 2-4 short terminal spines and sometimes outer edge spine (Undinella), or with 2 strong terminal articulated spines and 2 strong subterminal articulated (1 outer and 1 inner) spines (Rythabis).
Males
A1 21-23-segmented. Oral parts similar to female, nevertheless setation may be reduced.
P1-P4 as in females. P5 in Parundinella biramous, asymmetrical; left leg Exp 3-segmented, first segment with inner proximal process, Enp 1-2-segmented; right leg Exp 2-segmented, Enp in part fused with Basis; in other tharybids P5 usually biramous on left, uniramous on right; left leg with 2 basal segments, Exp 3-segmented, shorter than 1-segmented Enp; P5 right leg 3-segmented.
The family Tharybidae includes the following genera, of which only Tharybis is recorded in the South Atlantic:
Genus Tharybis Sars, 1902
Genus Undinella Sars, 1900
Genus Parundinella Fleminger, 1957
Genus Rythabis Schulz, 1995.
Pseudophaenna Sars, 1902 and Neoscolecithrix Canu, 1896 were tentatively placed in the family (Bradford et al., 1983). Recently Schulz and Beckmann (1995) proposed more likely placement of Neoscolecithrix into Phaennidae, or even more probably, the Scolecitrichidae.