Fig. 4

Structure of the propodal process. a Optical section through an intact propodus-dactylus joint illustrating how the edge of the propodal process fits into the groove of the dactylus. An arthrodial membrane (arrows) connects the two podomeres. b Scanning electron micrograph of the propodal process with the dactylus removed. The tip of the propodus ends with a semicircular cuticular plate with a thickened edge. Parallel ridges are present on the concave surface of the thick edge; on its convex surface, they are only present dorsally. The convex surface of the ventral half of the edge and the concave surface of its most dorsal part are smooth (asterisks). c Higher magnification image of the dorsal part of the propodal process, showing the oblique ridges arranged in a herringbone pattern. Arrowheads point to particles lodged between the ridges on its surface. d Detail of the ventral part of the edge, showing the ridges on its concave surface and its smooth convex surface. Particles are visible between the ridges (arrowheads). Scale bars: 20 μm (a), 10 μm (b), 2 μm (c and d)