Micro-CT analysis of the maxillo–lacrimal complex in Plecotus auritus (Linnaeus, 1758) and description of the processus intersuturalis maxillo–lacrimalis (nova structura)

Abstract The morphological organization of the maxillo–lacrimal region in the bat Plecotus auritus (Linnaeus, 1758) was investigated using micro-computed tomography (micro-CT). A consistent, bilaterally symmetrical anatomical complex was identified at the junction between the os maxillare and os lacrimale . This configuration includes a previously undescribed bony structure, the processus intersuturalis maxillo-lacrimalis (nova structura), proposed here as a descriptive anatomical term, located within the maxillo-lacrimal suture between the adjacent processus frontalis maxillae and processus nasalis ossis lacrimalis . The complex also includes a distinct additional opening, the foramen orbitonasale accessorium , clearly distinguished from the foramen infraorbitale. Serial sections further revealed the presence of a continuous canal, here termed the canalis maxillolacrimalis , with its course and opening into the nasal cavity clearly identifiable. All structures were consistently present in the examined specimens, exhibiting stable topography and high morphological repeatability. Available comparative descriptions suggest that this arrangement differs from the generalized mammalian condition, although directly comparable three-dimensional data remain limited. These findings demonstrate a consistent and previously unrecognized osteological organization of the maxillo-lacrimal region in P. auritus . Its functional significance remains unclear and requires further investigation.