Figure 23 from: Goulding TC, Khalil M, Tan SH, Dayrat B (2018) Integrative taxonomy of a new and highly-diverse genus of onchidiid slugs from the Coral Triangle (Gastropoda, Pulmonata, Onchidiidae). ZooKeys 763: 1-111. https://doi.org/10.3897/zookeys.763.21252

Figure 23 Penis, Wallaconchis buetschlii, Indonesia. A Longitudinal ridge on the internal surface of the penis, Kei Islands, scale bar 60 μm [2933] (UMIZ 00029) B Close-up of a groove between two longitudinal ridges showing smooth internal surface (no hooks), Sulawesi, scale bar 20 μm [2120] (UMIZ 00021).