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An Alternative Phylogeny of Peracarid Crustaceans

Les Watling

出版	1981
URL	http://books.google.com.hk/books?id=PWyjoAEACAAJ&hl=&source=gbs_api

註釋

In order to properly understand the origins of the Order Amphipoda, their phylogenetic position within the Superorder Peracarida must first ge established. A hypotetical ancestral paracarid is derived from Dahlś hypotetical ancestral eumalacostracan, which was proposed as lacking a carapace. The independent derivation of a carapace for special needs on at least two occasions is thus a central feature of a new phylogenetic arrangement for the peracaridan orders. This phylogeny is based on an analysis of 29 character states using Hennigian methods. Two lineages are immediately apparent: 1, a heterogeneous line containing the Amphipoda, Mysidacea, and Thermosbaenacea; and 2, a homogeneous "mancoid" line leading from the Isopoda through the Spelaogriphacea and Tanaidacea to the Cumacea. The mancoid line as proposed is inverted relative to earlier phylogenetic schemes; however, future examinations of the phylogeny of peracarid orders by based on a scheme for the Superorder, thus enabling plesiomorphic features of individual orders to be properly defined. Lastly, the polyphyletic nature of the Peracarida is discussed and it is suggested that at least three independent lines of "peracaridan" radiation might have aristen from a pre-Carboniferous syncarid-like ancestral eumalacostracan.