Six New Species of Fresh and Brackish Water Ostracods (Crustacea) from Yakushima, Southern Japan
Twelve species of brackish and freshwater ostracods were collected from the island of Yakushima in southern Japan. Six species, belonging to the genera Cypria, Dolerocypris, Stenocypris, Schellencandona and Paracypria, are new and are described herein. The genus Schellencandona is reported for the first time outside Europe. Although a wide range of apparently suitable habitats was sampled for ostracods across the island, all specimens were recovered from or near the coast; further inland yielded no ostracods. The freshwater habitats around the coast of the island consist of springs and rockpools at the top of the shore above most high tide levels.
The chaetotaxy of Cypridacea (Crustacea, Ostrocoda) limbs: proposals for a descriptive model
The need for better and more systematic descriptions of the chaetotaxy (especially data concerning the shape, structure and pattern of distribution of the setae) is emphasized. The historical developments of studies in chaetotaxy are reviewed. Two basic types of cuticular processes can be recognized: setae and pseudochaetae. The former have sensorial and mechanical functions, the latter only a mechanical function. A special type of seta is the aesthetasc or the chemosensorial receptor. Using the shape and structure of the setae, most of them can be classified in the following categories: simple, plumed, serrate and chelate. The importance of developmental studies for the establishment of homologies in chaetotaxy is stressed. Examples of functional morphology of setae are discussed. It is emphasized that the functional morphology of most of the setae can be better understood when the whole organ is studied of which the setae are only a component. Not all the setae have an adaptive significance. A descriptive model of the chaetotaxy of cypridacean ostracods is presented. The different characteristics of the setae as well as their position on the limbs are coded by letters and numerals using simple formulae.
Taphonomy of Isisfordia duncani specimens from the Lower Cretaceous (upper Albian) portion of the Winton Formation, Isisford, central-west Queensland
Taphonomic analysis of fossil material can benefit from including the results of actualistic decay experiments. This is crucial in determining the autochthony or allochthony of fossils of juvenile and adult Isisfordia duncani, a basal eusuchian from the Lower Cretaceous (upper Albian) distal-fluvial-deltaic lower Winton Formation near Isisford. The taphonomic characteristics of the I. duncani fossils were documented using a combination of traditional taphonomic analysis alongside already published actualistic decay data from juvenile Crocodylus porosus carcasses. We found that the I. duncani holotype, paratypes and referred specimens show little signs of weathering and no signs of abrasion. Disarticulated skeletal elements are often found in close proximity to the rest of the otherwise articulated skeleton. The isolated and disarticulated skeletal elements identified, commonly cranial, maxillary and mandibular elements, are typical of lag deposits. The holotype QM F36211 and paratype QM F34642 were classified as autochthonous, and the remaining I. duncani paratypes and referred specimens are parautochthonous. We propose that I. duncani inhabited upper and lower delta plains near the Eromanga Sea in life. Their carcasses were buried in sediment-laden floodwaters in delta plain overbank and distributary channel deposits. Future studies should refer to I. duncani as a brackish water tolerant species.