Abstract Two fossils from Burmese amber are the subject of this study. The specimens differ in size; yet, they appear to be conspecific because of the profound morphological similarity. The fossils are interpreted as representatives of Isopoda, more precisely of the group Cymothoida, due to the presence of a triangular basipod of the uropod. Cymothoida comprises parasitic forms of Isopoda as well as many other types of feeding-habits. The morphology in the studied fossils suggests that they are not representatives of any of the parasitic ingroups of Cymothoida. Since there are no other findings of Isopoda from the Cretaceous with the same morphological features, the fossils at hand are described as a new species - Electrolana madelineae sp. nov. The smaller specimen lacks well-developed walking appendages on trunk segment seven; it can thus be interpreted as a manca stage (immature) individual. The systematic affinity and the functional morphology of the herein described fossils, as well as three seed shrimps (Ostracoda) in close proximity to one of the specimens, and the presence of pyrite in the amber piece points towards an aquatic lifestyle and a preservation in moist conditions. In addition, we review the fossil record of immature forms of Isopoda.

Abstract From the lower Miocene (Burdigalian) of the Qom Formation, exposed in three sections (Kuh-e-Donbeh, Bagher-Abad, and Vartun) in Central Iran, a decapod crustacean assemblage is described. The specimens exhibit two modes of pres-ervation: carapaces (either isolated or with attached appendages) and isolated cheliped elements. All studied specimens are fractured and/or eroded. Based on this moderately preserved material, three brachyuran crab taxa are identified, including Mursia cf. lienharti (Bachmayer, 1962), Palaeocarpilius rugifer Stoliczka, 1871, and Necronectes sp. The occurrence of P. rugifer represents the youngest confirmed occurrence of the species, whereas other two taxa represent the first confirmed Iranian occurrences of respective genera. This report enriches our knowledge on Miocene decapod assemblages of Iran, and thus helping to better understand the decapod migratory patterns along the Tethyan Seaway.

Resumen Se describe un conjunto de crustáceos decápodos correspondientes a la Formación Quom del Mioceno inferior (Burdigaliano) en tres regiones de Irán central (Kuh-e-Donbeh, Bagher-Abad y Vartun). Los especímenes exponen dos modos de preservación: caparazones (ya sea aislados o con apéndices adheridos) y elementos aislados quelípedos. Todos los ejemplares aquí estudiados están fracturados o erosionados. Con base en este material moderadamente conservado, se identificaron tres taxones de cangrejos braquiuros incluyendo Mursia cf. lienharti (Bachmayer, 1962), Palaeocarpilius rugifer Stoliczka, 1871 y Necronectes sp. Además, P. rugifer es el indicio confirmado más reciente de esta especie, mien-tras que los otros dos taxones son las primeras muestras iraníes en estos respectivos géneros. Este informe enriquece nuestro conocimiento sobre los conjuntos de decápodos del Mioceno en Irán, lo que contribuye a una mejor comprensión sobre los patrones migratorios de decápodos a lo largo de la vía marítima de Tetis.

A rich decapod fauna from the Early Pleistocene (late Gelasian-early Calabrian) of Poggio i Sodi quarries (Siena, Tuscany, central Italy) is here reported. Integrated biostratigraphical, sedimentological and paleoecological analyses have been carried out, and some paleoenvironmental inferences are also proposed. The studied decapod community is herein assigned to the upper bathyal; several paleoenvironmental factors (cool water conditions at the sea floor, clay soft bottom, nutrients, very low environmental energy and sedimentation rate) influenced and promoted the crustacean settlement.

Se reporta una fauna diversa del Pleistoceno Temprano (Gelasiano tardío-Calabriano temprano) de las canteras Poggio i Sodi (Siena, Toscana, Italia central). Se realizaron análisis integrados de bioestratigrafía, sedimentología y paleocología y algunas inferencias paleoeoambientales son propuestas. La comunidad de decápodos estudiada es aqui referida a la zona batial superior; varios factores paleoambientales (condiciones de agua fría en el fondo marino, fondo de arcilla suave, nutrientes, energía ambiental muy baja y tasa de sedimentación) influyeron y promovieron el asentamiento de los crustáceos.

On the basis of newly collected material, two ghost shrimp taxa from the lower Maastrichtian Ocozocoautla Formation in Chiapas (Mexico) are recorded. Callianassa burckhardti is reassigned to Eucalliax, which extends the known fossil record of this genus to the early Maastrichtian. A new species, Callianassa (s.l.) ocozocoautlaensis, is described based on a single specimen whose state of preservation does not enable a firm generic assignment, despite the fact that the material exhibits striking similarities to extant Callianassa modesta, occasionally treated as a member of the genus Cheramus. The fossil record of ghost shrimps from Mexico is briefly reappraised and their survival across the K/Pg boundary is discussed. The conservative body plan of ctenochelid and callianassid taxa is emphasized and it is postulated that virtually all major ghost shrimp clades were already established well before the Cenozoic.

Con base en material recientemente colectado, se reportan dos taxa de camarones fantasma de la Formación Ocozocoautla del Maastrichtiano inferior de Chiapas (México). Callianassa burckhardti es reasignada a Eucalliax, por lo que el registro fósil del género respectivo se extiende al Maastrichtiano temprano. Una especie nueva, Callianassa (s.l.) ocozocoautlaensis, se describe con base en un solo especimen, cuya preservación no permite la identificación confiable a nivel de género, aunque el material exhibe fuertes afinidades con la especie existente Callianassa modesta, que en ocasiones es tratada como un miembro de Cheramus. El registro fósil de camarones fantasma de México es brevemente reevaluado, y se discute su supervivencia a través del límite K/P. Se enfatiza el plan conservativo de los taxa de ctenoquélidos y calianásidos, y se postula que virtualmente todos los clados mayores de camarones fantasma se establecieron antes del Cenozoico.