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Comparative studies on the structure and development of the venom‐delivery system of centipedes, and a hypothesis on the origin of this evolutionary novelty
Author(s) -
Dugon Michel M.,
Arthur Wallace
Publication year - 2012
Publication title -
evolution and development
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.651
H-Index - 78
eISSN - 1525-142X
pISSN - 1520-541X
DOI - 10.1111/j.1525-142x.2011.00527.x
Subject(s) - biology , appendage , venom , centipede , evolutionary biology , anatomy , zoology , ecology
SUMMARY The venom‐injecting forcipules of centipedes represent an evolutionary novelty that appeared in the centipede stem lineage more than 400 Ma. No other lineage of arthropods (or indeed of animals) has evolved claws for injecting venom from a pair of walking legs. However, little is known of the development, ultrastructure, or detailed function of centipede forcipules. Here, we provide comparative structural information on the venom duct apparatus that is the main functional system within each forcipule, based on scanning electron microscopy and transmission electron microscopy studies. We also give comparative developmental information, using DAPI staining, on embryonic forcipules from the four main centipede orders, including S cutigeromorpha. The photographs of S cutigera embryos we present are the first to be published for any species belonging to this order. The structure of the venom apparatus within each forcipule represents a discrete element of the novelty, whose origin requires a special explanation. This is in contrast to the novel external shape of the forcipules, which can be arrived at gradually by a series of changes from the starting point of a standard walking leg. Drawing on a proposed structural homology between venom glands and epidermal glands, we present a hypothesis of how the venom gland and duct may have arisen in evolution.