Comparative gastrointestinal morphology of seven golden mole species (Mammalia: Chrysochloridae) from South Africa.

Golden moles are small, fossorial, and primarily insectivorous mammals mostly endemic to South Africa. They belong to an ancient African clade of placental mammals (Afrotheria) that likely radiated from an herbivorous ancestor. Nearly half of the 21 golden mole species are listed as threatened; but remarkably little is known about their basic biology and gastrointestinal tract (GIT) morphology. This study provides a morphometric and histochemical analysis of the GIT of seven chrysochloridae species, including three threatened taxa. Macroscopically, all species examined had simple GITs with simple, wholly glandular stomachs and no cecum. Histologically, the pylorus was dominated by parietal cells. Neutral mucin cells were found on the luminal surface and in the gastric pits, while mixed acid and neutral mucin cells were found in the proximal parts of the gastric glands. The proximal intestine had typical small intestinal histological features such as villi. Typical colonic mucosal features were absent as villi were present throughout the intestinal tract. Goblet cells were abundant and increased toward the distal intestine. These intestinal goblet cells contained mostly mixed mucins. Stomach and intestinal content analysis confirmed the presence of arthropod exoskeleton material and possible small vertebrate remnants, commensurate with a low-fibre, protein-rich diet. This may account for their simple GIT morphology, as seen convergently in other unrelated insectivorous mammals. This study provides better representation of variation in GIT morphology among chrysochloridae and within the enigmatic Afrotheria clade. Additionally, it provides a better understanding of the mucin distribution in relation to diet and phylogeny of golden moles.