Sars, 1902
Females
Small copepods slightly over 1 mm. Usually with characteristic eye composed of pigmented spot surrounded by refractile lens. Ce and Pd1 fused or separate, Pd4 and 5 fused or separate; posterior metasomal corners may be rounded or variously decorated with large posterior spines or rows of spinules. Ce with pair of rostral filaments. Ur of 2-4 somites, may be asymmetrical; Gns very variable (symmetrical, asymmetrical, ornamented with spines and/or spinules, or undecorated), CR tend to be elongate and may be asymmetrical. A1 symmetrical, usually 22-segmented (24-segmented in Archidiaptomus, 21-segmented in the Hyalinus group of Pseudodiaptomus). A2 Exp slightly longer than Enp, Enp with fusion between segments and with Basis. Md gnathobase with numerous small teeth. Mx1 Li1 usually with with 15 spines and setae, Li2 and 3 with 3 setae each, Li4 with 5 setae, Enp segments 1-3 with 4, 4, 5 setae respectively, Exp with 10 setae, Le1 with 10 setae. Mx2 Li1-5 with 4, 3, 3, 3, 3 setae respectively. Mxp Coxa squat with 2, 3, 4 setae, one of terminal group enlarged into spine; Basis bordered by spinules and 3 setae; Enp 4-segmented, often carrying 4 characteristic setiform bristles (2 on segment 1 and 1 each on segments 2 and 3). P1-4 biramous, with 3-segmented rami; Coxa and Basis often decorated with spinules on anterior, posterior and lateral surfaces, also sometimes on anterior surfaces of Enp and Exp.
Spine and setae formula: Spine & seta Pseudodiaptomidae.
P5 uniramous or biramous; not natatory; with 3 Exp segments (the terminal 2 may be fused); may be slightly asymmetrical. Ovisacs present.
Males
Body of similar form to female, Ur of 5 somites. A1 asymmetrical; left 22- or 24-segmented; right with 20-21 segments, geniculate between segments 18 and 19; terminal part beyond joint can have from 2-4 segments. P5 uniramous or biramous, very asymmetrical; Exp 2- or 3-segmented; spines, Exp segments, and Enp, if present, variously modified into a form which appears to be adapted for clasping.
Sars (1902) proposed the family Pseudodiaptomidae to include Pseudodiaptomus Herrick, 1884, and Poppella Richard, 1888 (junior synonym of Calanipeda), but did not define it. The above definition has been created from a definition of Pseudodiaptomus (Madhupratap and Haridas, 1978; Walter, 1986).
This family contains three genera, of which only Pseudodiaptomus has been taken in the South Atlantic:
Genus Archidiaptomus Madhupratap and Haridas, 1978
Genus Calanipeda Kritchagin, 1873
Genus Pseudodiaptomus Herrick, 1884