Myodocopina Sars 1866

Kornicker, Louis S., Van, Barry W. M., Bakel, Fraaije, René H. B. & Jagt, John W. M., 2006, Revision of Mesozoic Myodocopina (Ostracoda) and a new genus and species, Mesoleberis hollandica, from the Upper Cretaceous of Belgium and The Netherlands, Zootaxa 1246, pp. 15-54 : 21

Suborder Myodocopina Sars 1866

Composition

The Myodocopina contain the superfamilies Sarsielloidea, Cypridinoidea, and Cylindroleberidoidea ( Kornicker & Sohn 2000:18). Extant members of the three superfamilies are recognized mainly by morphology of soft parts. With the exception of members of the tribe Bruuniellini Kornicker & Harrison­Nelson 2005, representatives of the Cylindroleberidoidea bear gills. Mesozoic specimens of Juraleberis jubata Va n ni e r & Siveter 1995 and Triadocypris spitzbergensis Weitschat 1983 b have some appendages resembling those of extant Cylindroleberidoidea and have been referred to that superfamily. The former species may bear gills, and the latter species bears three gills on each side (extant species bear about seven gills on each side).

Fossils of Myodocopina represented only by carapaces are difficult to identify with certainty, because extant representatives of superfamilies vary in shape of carapace and in patterns of central adductor muscle scars. The latter are often lacking in fossil carapaces. Kornicker & Sohn (2000:18) presented a key to Paleozoic and Mesozoic superfamilies based on the morphology of the rostrum and incisure. In that key the Cypridinoidea and Cylindroleberidoidea are separated on the rostrum and incisure, those being well developed in the former and poorly developed in the latter. Although of some use, the degree of development of the rostrum and incisure on valves of some species is difficult to categorize. Unless some soft parts are preserved in fossils, the senior author doubts that Paleozoic or Mesozoic ostracodes in the Cylindroleberidoidea and Cypridinoidea can be separated with a high degree of certainty. Kornicker & Sohn (2000:1) did not use muscle scar patterns in keys, because they are rarely preserved in fossil Myodocopina . They are preserved in some of the Mesozoic species considered herein and have been used to differentiate taxa.

Ten species from the Mesozoic that have been assigned to the Myodocopina herein have been placed in the superfamily Cylindroleberidoidea, family Cylindroleberididae : two in the subfamily Cyclasteropinae and eight in the subfamily Asteropteroninae . If the assignments are correct, their abundance suggests that members of the Cylindroleberididae were dominant during the Mesozoic. The fact that the only two species with soft parts that have been collected in the Mesozoic belong in that family supports their dominance. However, the similarity in carapaces of some species in the families Cypridinidae and Cylindroleberididae makes it quite likely that some of the fossils have been incorrectly referred to the Cylindroleberididae .

One unnamed species from the Jurassic of France has been assigned tentatively to the superfamily Cypridinoidea, family Cypridinidae . The species ( Cypridina sp.) was described in a dissertation by Françoise Dépêche (1984), who kindly agreed to publish the description herein, and to whom it is to be solely attributed.