Middle Archaic earthen mound complexes in the lower Mississippi valley are remote antecedents of the famous but much younger Poverty Point earthworks. Watson Brake is the largest and most complex of these early mound sites. Very extensive coring and stratigraphic studies, aided by 25 radiocarbon dates and six luminescence dates, show that minor earthworks were begun here at ca. 3500 B.C. in association with an oval arrangement of burned rock middens at the edge of a stream terrace. The full extent of the first earthworks is not yet known. Substantial moundraising began ca. 3350 B.C. and continued in stages until some time after 3000 B.C. when the site was abandoned. All 11 mounds and their connecting ridges were occupied between building bursts. Soils formed on some of these temporary surfaces, while lithics, fire-cracked rock, and fired clay/loam objects became scattered throughout the mound fills. Faunal and floral remains from a basal midden indicate all-season occupation, supported by broad-spectrum foraging centered on nuts, fish, and deer. All the overlying fills are so acidic that organics have not survived. The area enclosed by the mounds was kept clean of debris, suggesting its use as ritual space. The reasons why such elaborate activities first occurred here remain elusive. However, some building bursts covary with very well-documented increases in El Niño/Southern Oscillation events. During such rapid increases in ENSO frequencies, rainfall becomes extremely erratic and unpredictable. It may be that early moundraising was a communal response to new stresses of droughts and flooding that created a suddenly more unpredictable food base.
An 11-mound site in Louisiana predates other known mound complexes with earthen enclosures in North America by 1900 years. Radiometric, luminescence, artifactual, geomorphic, and pedogenic data date the site to over 5000 calendar years before present. Evidence suggests that the site was occupied by hunter-gatherers who seasonally exploited aquatic resources and collected plant species that later became the first domesticates in eastern North America.
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.. Society for Freshwater Science is collaborating with JSTOR to digitize, preserve and extend access to Freshwater Invertebrate Biology. Abstract. During the summer of 1984, free-swimming colonial rotifers were collected incidental to field studies on mosquitoes in 335 rice fields in southwestern Louisiana. Six of the seven known species of free-swimming colonial flosculariid rotifers were found: Lacinularia elliptica Shepard, L. flosculosa (Mueller), L. ismailoviensis (Poggenpol), Sinantherina semibullata (Thorpe), S. socialis (Linnaeus) and S. spinosa (Thorpe). Lacinularia causeyae n. sp., a species new to science, was collected and is described herein. Of the 335 fields sampled, 225 fields had at least one species of these rotifers, which were locally abundant. Estimates of relative abundance are presented. Although there are many species of sessile colonial rotifers, only nine species are known to form free-swimming colonies. Two species, Conochilus hippocrepis (Schrank) and C. unicornis Rousselet (Flosculariacea: Conochilidae), were reported from northern Louisiana (Gallagher 1966). The remaining seven species (Flosculariidae) are discussed herein. The entire group was monographed by H lava (1908); synonomies are contained in Harring (1913). Other pertinent general references include Donner (1966), Edmundson (1959), Hudson and Gosse (1886) and Pennak (1978).In general, the biology of the free-swimming colonial flosculariid rotifers is poorly understood. Zoogeographic information on most species is scant. Colonies that are commonly encountered contain only females. Related sessile flosculariid species include: This paper describes a species new to science, reports the relative abundance of seven free-swimming colonial rotifers in Louisiana rice fields, and provides an updated listing and key to the female colonies of free-swimming colonial flosculariid rotifers of the world.
Freshwater pearl mussels (Bivalvia: Margaritiferidae) are among the most imperiled groups of animals globally. While the parasites and symbionts of the Margaritiferidae are rather poorly known, these mussels were thought to be free of parasitic mites (Acari: Unionicolidae: Unionicola). Here, we report on the discovery of a mite species being associated with the endangered freshwater pearl mussel Gibbosula laosensis (Lea, 1863) from Myanmar. This species, Unionicola (Gibbosulicola) sella subgen. & sp. nov., morphologically resembles mites belonging to the subgenera Coelaturicola and Fulleratax (African and Southeast Asian groups, respectively). Our novel discovery expands the host range of Unionicola mites and reveals that all freshwater mussel families of the order Unionida host these aquatic mites. Our phylogenetic research and available published data reveal that the mussel-associated mite assemblage in Southeast and South Asia contains not less than 17 species and 8 subgenera. Currently, the regional taxonomic richness of this group seems to be largely underestimated. We found that mussel mites from Southeast Asia are narrow host specialists, which are known to occur in a single or a few closely related species belonging to one or two sister genera of freshwater mussels. Finally, our results indicate that mussel mites share generally restricted ranges and that their distribution patterns in Southeast Asia are largely congruent with the boundaries of biogeographic subregions delineated on the basis of phylogenetic studies of freshwater mussels. 614 | CHAPURINA et Al. 1 | INTRODUC TI ON The mantle cavity of freshwater mussels (order Unionida) is a home for a plethora of protists and metazoans, for example, ciliates, leeches, oligochaetes, mites, mayflies, dragonflies, crustaceans, and fishes (Brian &
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