Cypridocopina Baird, 1845

Bisquert-Ribes, Maria, Rueda, Juan, Palero, Ferran, Savatenalinton, Sukonthip & Mesquita-Joanes, Francesc, 2023, Fig. 1 in Fig. 4 in Identification of Sexually Dimorphic Genes in Pectoral Fin as Molecular Markers for Assessing the Sex of Japanese Silver Eels ()., Zoological Studies 62 (40), pp. 1-24 : 3

Suborder Cypridocopina Baird, 1845 Superfamily Cypridoidea Baird, 1845 Family Cyclocyprididae Kaufmann, 1900

Diagnosis (after Cyclocypridinae sensu Meisch (2000) and Karanovic (2012)): Carapace short, less than 1 mm in length, relatively stout in lateral view (except Allocypria , with elongated valves), moderately compressed to ovate in dorsal view. Eyes fused with a single eye cup. A1 usually 7-segmented and Rome organ present. Male sexual bristles on A2 (transformed t2 and t3 setae) present or absent, swimming-setae usually well-developed, sometimes reduced and rarely absent. Endopod of female T1 developed, transformed into 2-segmented prehensile palps in males. T3 (cleaning leg) always 4-segmented, last segment bearing two short (h1 and h2) and one long (h3) setae. Zenker organ with seven spine whorls (five along the central tube, and one at each end of the organ) and proximal part (entrance) spherically enlarged (not funnel shaped). CR not reduced and sp-seta insertion around medial part of CR.

Differential diagnosis: The family Cyclocyprididae can be distinguished from other Cypridoidea families through its Zenker organ (not funnel-shaped proximally and with seven spine whorls) and other characters of the soft parts and valves. In the case of the Zenker organ of Cyprididae Baird, 1845 , it has at least 8 spine whorls and their T3 has a pincer organ in most species (absent in Cyclocyprididae ). The Zenker organ of Ilyocyprididae Kaufmann, 1900 has 15–20 spine whorls, and members of this family have a subrectangular carapace (ovate or subovate in Cyclocyprididae ). Members of the Notodromadidae Kaufmann, 1900 present a unique Zenker organ, funnel-shaped in both extremes and with spines not arranged in separate whorls. Moreover, members of this family also present a divided eye (not divided in Cyclocyprididae ) and external eye tubercles (not present in Cyclocyprididae ). Candonidae s.str. (previously subfamily Candoninae ) lack the Rome organ of A1 and the swimming-setae of A2, which are usually present and well-developed in Cyclocyprididae . Moreover, these two families can be differentiated by the prehensile palps of T 1 in males; 2-segmented in Cyclocyprididae and 1-segmented in Candonidae . Paracyprididae differs from Cyclocyprididae by the presence of d1 and d2 setae on T2 (d2, and sometimes also d1, absent in Cyclocyprididae ) and the marine ecological affinities of most of its representatives (freshwater in the Cyclocyprididae ). However, more studies on Paracyprididae are needed to be able to give a more reliable differential diagnosis at the family level.