Synopsis of the genera Sesarma, Metasesarma, Sarmatium and Clistocoeloma, with a key to the determination of the Indo-Pacific species

Abstract

The genus Sesarma, established in 1817 by Say to receive an American form has turned out to contain such a large number of species, that it is nowadays one of the most difficult ones to the systematist. No less than about 130 species without the subspecies are included in it. In dealing with so many forms the need of subdivision naturally presents itself, and so de Man in 1887 (Zool. Jahrb. Syst., Bd. 2) firstly distinguished four subgenera, to which in 1895 (Zool. Jahrb. Syst., Bd. 9) he gave the names of Sesarma s.s., Episesarma, Parasesarma and Perisesarma. But already two years afterwards the often tyrannic exigencies of priority in nomenclature induced Miss Rathbun (Proc. Biol. Soc. Washington, v. 11) to alter the first two names into Holometopus and Sesarma s.s. respectively, and in 1909 (Proc. Biol. Soc. Washington, v. 22) this author again substituted the name Chiromantes Gistel for de Man's Perisesarma, so that now only Parasesarma has been left undisturbed. Every carcinologist will be ready to acknowledge de Man's great merits in affording the most accurate and minute informations about insufficiently-known species and in describing new ones with such accuracy that we may safely follow his lead amongst the intricacies and sometimes bewildering complexities that present itself in Decapod literature. In the particular case we are now dealing with it is he, who has examined by far the greater number of species, at least those from Indo-Pacific origin, and as most of his material is represented in the Leiden Museum the present author has had ample occasion to test the reliability of his own determinations. In some doubtful cases Dr. de Man with never failing helpfulness has been always willing to give his advice and needless to