Micropotamogale lamottei, Heim de Balsac, 1954

ASHER, ROBERT J., 2001, Cranial Anatomy in Tenrecid Insectivorans: Character Evolution Across Competing Phylogenies, American Museum Novitates 3352, pp. 1-55 : 32-33

Micropotamogale lamottei (IZEA 939)

The vomeronasal organ of Micropotamogale is approximately 3.5 mm in length and does not reach as far posteriorly as the first ethmoturbinal; in an adult specimen (IZEA 939) it extends only as far back as a frontal plane posterior to the canines and anterior to the anteriormost premolars (slice 48.3.2). In this specimen (IZEA 939) the vomeronasal organ comprises about 13% of nasal fossa length (ca. 26 mm) and 7% of head length (ca. 50 mm). Fetal specimens (i.e., AIG 2273–1, 2273–3) show a more elongate vomeronasal organ, but still shorter than that seen in a Potamogale of comparable age (table 2). No major blood vessels are apparent coursing along the length of the vomeronasal organ; instead, numerous smaller vessels are visible.

Most of the support for the vomeronasal organ along its length is ossified, although some paraseptal cartilage remains ventral and lateral to the organ. In this regard, Micropotamogale resembles the specimens of Geogale described below. This is due to the advanced ontogenetic stage represented by the IZEA 939 Micropotamogale and all Geogale individuals (all showing fully erupted teeth).

Anteriorly, the cartilaginous outer bar does not cover the vomeronasal organ laterally. The vomeronasal ducts are apparent at the anterior extreme of the vomeronasal organ, consisting of tubes on either side of the nasal septum that empty into each nasopalatine duct, separated from the nasal fossa proper (e.g., slice 31.3.2). Elongate, thin cartilages support each nasopalatine duct laterally, and line the posterior margins of each incisive foramen (e.g., slice 32.1.2; fig. 27). These cartilages are not connected to other nasal floor or septal cartilages. The palatine papilla of Micropotamogale is dorsoventrally elongate, defined by each nasopalatine duct laterally (slice 32.1.2; fig. 27).

Anterior to the incisive foramina and dorsal to the premaxilla, the anterior transverse lamina is evident (slice 21.3.2) and shows no connection with paraseptal cartilages.

Immediately anterior to the premaxilla, the nasal cartilages form an uninterrupted ring, or zona annularis, connecting the nasal sidewall, floor, and roof (slice 17.3.1).

As in Potamogale , and in concordance with the observation that a lacrimal foramen is reduced in adult Micropotamogale skulls (Asher, 1999), Micropotamogale shows no nasolacrimal duct. Both potamogalines do, however, possess a duct for the lateral nasal gland that travels from the posterolateral nasal fossa anteriorly, ventral to the nasoturbi­ nate (e.g., slice 35.3.2; see fig. 26 for the same structure in Erinaceus ).

Well anterior to the nasopalatine ducts and the posterior margin of the anterior transverse lamina, the superior and inferior septal ridges are apparent (slice 10.3.1). Neither pair of ridges shows cartilaginous support.

The superior alar processes of Micropotamogale are smaller than those of Potamogale and do not extend far posterior or lateral to the nasal cupula. They originate posteriorly from the lateral margin of the anterior nasal floor (slice 7.1.2). No dorsal projections are evident on the anterior cartilaginous nose in the available adult specimens (IZEA 939), but they are evident in embryos (AIG 2273–1, 2273–3).