Preliminary phylogenetic analysis of the bivalve family Galeommatidae

Publication Type:Journal Article
Year of Publication:1992
Authors:R. Bieler, Mikkelsen P. M.
Journal:American Malacological Bulletin
Accession Number:ISI:A1992JK73500006
Keywords:bivalvia, galeommatidae, mollusca, phylogeny, shell morphology

A preliminary phylogenetic analysis of species assigned to the ill-defined family Galeonunatidae, plus selected others, was attempted in an effort to clarify the relative value of various systematic characters. Aspects of dealing with large numbers of equally parsimonious trees in cladistic analyses and intrinsic problems of analyses based on unordered multistate characters are addressed briefly. The analysis (Hennig86, implicit enumeration) of 18 characters with 46 character states for 20 species yielded 164 equally parsimonious trees (length 52, ci 53, ri 72), displaying five distinctly different branching patterns. Separate consensus trees were produced for the five groups. Of the five topologies, one is considered most likely in an evolutionary context, and is discussed in detail. Three consistent species groups were recognized: 1) Divariscintilla group (eight species); 2) Galeomma-Ephippodonta group (six species); and 3) Scintillona-Ceratobornia group (three species). Two specialized anatomical characters were analyzed for relative systematic value: 1) "hanging" foot morphology, which could have evolved more than once within the Galeommatoidea; 2) flower-like organs, a possible synapomorphy of the Divariscintilla species-group. Results also indicated that the monospecific Phlyctaenachlamys Popham, 1939, is a junior subjective synonym of Divariscintilla Powell, 1932, and suggested that the generic limits of Galeomma Sowerby In: Turton, 1825, and Ephippodonta Tate, 1889, should be reexamined. Data matrix construction further identified potentially valuable, but currently unusable, characters in need of further investigation: occurrence of flower-like organs; foot morphology including byssus gland(s); homologies of hinge teeth; ligament/resilium apparatus; shell microstructure; reduction/loss of ctenidial interlamellar junctions and outer demibranch; presence/extent of midgut typhlosole, innervation of pallial tentacles, and sperm structure.

URL:<Go to ISI>://A1992JK73500006
Alternate Journal:Am Malacol BullAm Malacol Bull
Tue, 2010-06-29 04:17 -- ilya
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith