Fig. 4

Three-dimensional surface models of whole muscles and glands in the labrum and paragnath of all four heterorhabdid species: a) Disseta palumbii, b) Mesorhabdus gracilis, c) Heterostylites longicornis, D) Heterorhabdus subspinifrons. The PDF version of the paper contains interactive 3D content that can be activated by clicking on each figure panel in Adobe Reader. To view/exclude individual drawing elements: 1) click on a figure panel to activate it, 2) click on the “Toggle Model Tree” icon in the 3D tool bar to display viewing options, and 3) check/uncheck drawing elements to include/exclude specific elements. In any view, use the scroll function to zoom in/out and click/drag the cursor to rotate the view. To observe the specific views referred to in the text, select the named view from list of views in the “Model Tree” side bar (for a detailed explanation of interactive 3D viewing functions, see Additional file 1: Figure S1). Color codes as in Fig. 2, except for yellow- labral gland and paragnathal epidermal gland, and tan- esophagous. Note: the orientation of the X-Y-Z axis indicators are arbitrary for each panel and are not comparable among panels