Broad phylogenetic analyses of the leech family Glossiphoniidae (Annelida: Clitellata) reveals two independent origins of kangaroo leeches

Abstract

Abstract Parental care is uncommon within Annelida. However, a remarkable exception is in the leech family Glossiphoniidae in which all its members keep their offspring attached to the ventral surface for varying lengths of time. Considered as the culmination in the evolution of parental care in leeches, two glossiphoniids, Marsupiobdella africana from South Africa and Maiabdella batracophila from South America, have a brood pouch or marsupium in which their offspring are protected. Interestingly, the structure is located in exactly the same region of the body in both species. Based on phylogenetic analysis of Glossiphoniidae, including use of nuclear and mitochondrial DNA sequences, we investigated for the first time the phylogenetic position of the two kangaroo leeches. Our results indicate that marsupium-bearing leeches belong to separate lineages, with each species more closely related to other leeches from their respective continent. We infer that the marsupium evolved independently from ancestors that maintained their eggs inside thin-walled, flexible, transparent cocoons attached directly to the ventral surface of the parents. Together with the evolution of a marsupium, both species have also ceased to produce cocoons, which are normally a characteristic of Glossiphoniidae.