Akademik

clypeus
An unpaired dorsal unit of the cephalon bearing the labrum medially and the mandibular fossae laterally. The fossae articulate with the dorsal condyle of the mandibles [Wilson, 1989].
Part of head carrying labrum; plate on anterior medial part of head formed by fusion of basal segments of antennae (e.g., Branchipus, also Hexapoda) [Moore and McCormick, 1969].
(Order Anostraca):
Part of cephalon carrying labrum; plate anteromedially on head formed by fusion of basal segments of antennae [McLaughlin, 1980].
(Order Anostraca):
Plate-like structure fromed by medial fusion of bases of antennae. (with/without digiform process). (Syn. frontal plate) [Stachowitsch, 1992].
(Order Tanaidacea):
On underside of head, plate-like structure bearing upper lip (labrum). Separated from labrum by suture [Stachowitsch, 1992].
(Order Isopoda):
In most (but not all) isopods the labrum consists of two pieces; the anteriormost (proximal) piece is referred to as the clypeus, the posteriormost (distal) piece as the labrum proper [Wetzer et al. 1997].
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Nomenclature of isopod cephalon (A). Examples of isopod mouth appendages: Idoteidae (B, C, F, H); Cirolanidae (D, E, G, I). [Wetzer et al. 1997]
(Order Isopoda):
Part of head (cephalon) bearing upper lip (labrum) [Stachowitsch, 1992].
(Order Isopoda):
Platelike structure of cephalon, anterior to upper lip or labrum, sometimes fused with frontal lamina [Kensley and Schotte, 1989].
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Schematic representation of an isopod illustrating morphological terms. [Kensley and Schotte, 1989]

Crustacea glossary. . 2011.