Histology of the fusion area between the parasitic male and the female in the deep‐sea anglerfish Neoceratias spinifer Pappenheim, 1914 (Teleostei, Ceratioidei)

The article deals primarily with the histology of the fusion area between the head of the male and the skin of the female in two female Neoceratias spinifer , each of which had a single parasitic male attached. In this area, comprising the whole flattened upper part of the male head, the dermis of the male is completely fused with that of the female, leaving no remnants of the epidermis of either. In all other known cases permanent attachment of the parasitic male is accomplished by fusion of separate outgrowths from the male snout and lower jaw and the female skin. In the fusion area of N. spinifer two interconnected blood vascular plexus are present, the one located in the connective tissue of the male head, the other in that of the female skin. It is not known, however, whether the plexus in the female skin is provided with blood from the female blood vascular system, i.e. there is no critical proof of a real continuity between the female blood vascular system and that of the male. The eyes of both parasitic males are very degenerate. There is no histological evidence of degenerative changes in the male digestive system, heart or gills.