Different hypotheses of the endite composition of the mandible based upon expression of Tc-dac. All views are medial to the left with distal top. Developing endites are represented by a dotted circle. Tc-dac expression is blue. (A) Schematic representation of Tc-dac expression in the distal part of an endite. (B) Hypothetic Tc-dac expression if the inner lobe and outer lobe are separate endites. Tc-dac is expressed in the distal part of the two endites. Non-endite expression of the proximal domain of Tc-dac also includes expression in the distal part of the protopodite (arrowhead). (C) Diagram of the actual expression of Tc-dac (shown in blue) and Tc-prd (shown in red). C o-expression of Tc-prd and Tc-dac is purple. Tc-prd is expressed in the inner and outer lobes. (D) Diagram of the actual expression of Tc-dac. Tc-dac is expressed in the outer lobe, and is lacking in the inner lobe. A circular gap in Tc-dac expression (asterisk) later appears in the outer lobe. (E) The hypothesis presented in this study, where there is one mandibular endite which includes both the inner and outer lobe. Tc-dac is expressed in the outer lobe, the distal part of the endite. (F) An alternative hypothesis based on Tc-dac expression where the mandible has two endites (indicated with a star and asterisk). There is no expression of Tc-dac in the inner lobe. Therefore the two endites do not correlate to the inner and outer lobe precisely. Rather, the proximal endite (star) includes the inner lobe and the proximal part of the outer lobe. The distal endite (asterisk) includes part of the outer lobe.