Systematic reviews on the Mesodesmatidae (Mollusca, Bivalvia) I. The Genus Monterosatus Beu, 1971

In trying to identify a small Mesodesma from West Irian, New Guinea, much material in the collections of several museums was studied. As a guide for the identification I at first used the revision of the Mesodesmatidae by Lamy (1914), which is based exclusively on the collections of the Parisian museums. This publication, however, soon proved to be inadequate in view of the vast amounts of material in other collections. New ideas about the classification of the Mesodesmatidae prompted me to revise the systematics of this family, and preliminary publications (De Rooij-Schuiling, 1972, 1973) have already dealt with some aspects of this revision. The present paper is the first of a series of revisions in which all species of Mesodesmatidae will be described and discussed in detail. These studies were made possible by the gracious co-operation of the staff and direction of many museums. For material concerning the genus Monterosatus my thanks are due to: Istituto di Geologia Paleontologia e Geografia Fisica, Torino, Italy (IGPGF); Institut Royal des Sciences naturelles de Belgique, Brussels, Belgium (Dautzenberg Collection) (IRSNB-D); Laboratoire de Biologie des Invertébrés marins et Malacologie, Muséum National d'Histoire Naturelle, Paris, France (LMP) and its Locard Collection (LMP-L). I am grateful to Dr. C. O. van Regteren Altena for calling my attention to this interesting group of molluscs and for his encouraging help, to Drs. H. Boschma, P. H. van Doesburg, L. B. Holthuis and W. F. Ponder for their advice, and to Dr. A. C. van Bruggen for stimulating discussions. The order Mactracea contains the two families Mesodesmatidae and Mactridae. The Mesodesmatidae comprise the genera Monterosatus, Ervilia,