Morphology of possible lattice organs in light microscopy
The possible lattice organs appear as oval spots of dark brown color clearly distinguishable from the surrounding light-brown cuticle of the carapace (Fig 1B, C and F). The largest possible lattice organs, found posteriorly in BM J 622-1, measure 300 × 150 µm. They consist of an outer dark rim with a width of 50 µm or more, which surrounds an approximately 150 × 50 µm lighter central area. This elongated, occasionally slightly pear shaped, area is often delimited by a slightly raised ridge or wall. Anteriorly the possible lattice organs in BM J 622-1 lack all but a trace of the dark rim and the light central area typically measures ~ 100 µm in length and less in width (Fig. 1D). Probably, the dark rim corresponds to an area with a thicker, more heavily tanned or otherwise differentiated cuticle (Fig. 2).