A mouthless late-term coach whipray Himantura uarnak embryo (Elasmobranchii, Dasyatidae) has implications for our understanding of matrotrophy in chondrichthyans

Maternal nutrient provisioning occurs in most live-bearing chondrichthyan lineages. It is particularly conspicuous in the Myliobatiformes, whereby the endometrium secretes a nutrient-rich histotroph that is utilized by the developing embryo. The occurrence of a deformed and mouthless, late-term myliobatiform embryo is described here, demonstrating that the direct, oral ingestion of histotroph is not obligatory in these animals.