scholarly journals Resting stage in benthic foraminiferal propagules: a key feature for dispersal? Evidence from two shallow-water species

2002 ◽  
Vol 21 (1) ◽  
pp. 95-96 ◽  
Author(s):  
Elisabeth Alve ◽  
Susan T. Goldstein

Abstract. Understanding dispersal mechanisms in benthic formainifera has wide implications for explaining their geological and biological distribution in space and time, including evolutionary and genetic trends. Because they lack a planktonic larval stage (although a few have a meroplanktonic life stage), their mode of dispersal in the marine environment has been subject to much speculation, and a range of alternative mechanisms have been suggested (for a review, see Alve (1999) and further discussion in Hayward et al. (1999)).In the present note, we suggest a mechanism which is more efficient and probably more widespread than most of those previously proposed. We hypothesize that many species produce ‘propagules’ (small juveniles, perhaps just the proloculus) released in large numbers following reproduction that may enter a resting stage. Propagules can be widely dispersed by normal physical processes (currents, sediment transport) and ultimately settle over a range of habitats and conditions. Growth and reproduction commence only in those individuals and species that reach a suitable environment. We have two lines of evidence from completely different shallow-water environments (Norwegian fjord and the Florida Keys, USA) that strongly support our hypothesis.ObservationsSurface sediments from a box core were collected at 60 m water depth in the inner part of Oslofjord 10 September 1999. Some of the sediment was processed immediately after collection, and the remaining bulk sample was transferred to a transparent container with ambient seawater, sealed, and placed on a window ledge until 30 March 2000. Those sub-samples processed immediately after collection contained no live . . .

Zootaxa ◽  
2016 ◽  
Vol 4184 (2) ◽  
pp. 386 ◽  
Author(s):  
THAYNÃ CAVALCANTI ◽  
GEORGE GARCIA SANTOS ◽  
EDUARDO HAJDU ◽  
ULISSES PINHEIRO

2012 ◽  
Vol 26 (3) ◽  
pp. 230 ◽  
Author(s):  
Julie Reveillaud ◽  
Céline Allewaert ◽  
Thierry Pérez ◽  
Jean Vacelet ◽  
Bernard Banaigs ◽  
...  

The identification of sponges that lack a mineral skeleton is always highly challenging, especially for Hexadella species, which are also fibreless. Recently, the yellow species Hexadella pruvoti Topsent was identified as a cryptic species complex while the pink coloured Hexadella racovitzai Topsent showed two highly divergent lineages. We performed a COI phylogenetic reconstruction using 27 new Mediterranean Hexadella samples in order to confirm the presence of divergent lineages within both shallow-water species. Specimens were described with an integrative approach combining morphological and cytological investigations, biochemical profiling and assessment of natural toxicity in order to identify diagnostic characters for each taxon. H. topsenti, sp. nov. is distinguished from H. racovitzai by its colour, its surface network shape, divergent secondary metabolite patterns and toxicity values. H. crypta, sp. nov. differs from H. pruvoti by a different encrusting growth form when alive, and by distinctively colouring the ethanol fixative solution. In addition, H. pruvoti and H. crypta show different types of cells with inclusions as well as distinct metabolic fingerprints. Natural toxicity values, however, do not permit the separation of H. pruvoti and H. crypta. Our work shows that only the use of a combination of complementary tools can provide relevant descriptions for some problematic taxa.


Zootaxa ◽  
2008 ◽  
Vol 1678 (1) ◽  
pp. 1 ◽  
Author(s):  
KIM LARSEN ◽  
MICHITAKA SHIMOMURA

Two new species of tanaids were collected from colonization traps deployed in a shallow water, sandy habitat off Akajima, Nansei Islands. One new parapseudidaen, Parapseudes arenamans, and one new nototanaidaen genus and species, Paranesotanais longicephalus, are described herein. A preliminary phylogenetic analysis of the closest genera confirms the validity of the new genus and suggests a close affinity between the Leptocheliidae and Nototanaidae. Paranesotanais longicephalus was by far the most abundant species in the habitat. Parapseudes arenamans is faster in colonization of vacant substrate (opportunistic species), while being an inferior competitor to Paranesotanais longicephalus later in succession. A key to Nesotanais and Paranesotanais is provided.


2016 ◽  
Vol 85 (1) ◽  
pp. 13-35 ◽  
Author(s):  
Magdalena Łukowiak

The late Eocene ‘soft’ sponge fauna of southern Australia is reconstructed based on disassociated spicules and is used to interpret the paleoecology and environmental context of shallow marine communities in this region. The reconstructed sponge association was compared with coeval sponge assemblages from the Oamaru Diatomite, New Zealand, and with the modern ‘soft’ sponge fauna of southern coastal of Australia. Based on the predominance of shallow- and moderately shallow-water species, the late Eocene assemblage is interpreted to have inhabited waters depths of about 100 m. This contrast with the spicule assemblage from New Zealand, which characterized deeper waters based on the presence of numerous strictly deepwater sponge taxa, and the absence of spicules of shallow-water demosponges represented in the Australian material. The southern Australian Eocene sponge assemblages have clear Tethyan affinities evidenced by the occurrence of sponges known today from diverse regions. This distribution suggests much wider geographical ranges of some sponge taxa during the Eocene. Their present distributions may be relictual. The modern sponge fauna inhabiting southern Australian waters shows only moderate differences from these of the late Eocene. Differences are more pronounced at lower taxonomic levels (family and genus).


Paleobiology ◽  
1976 ◽  
Vol 2 (2) ◽  
pp. 156-165 ◽  
Author(s):  
Thomas J. M. Schopf

Bryozoans are colonial animals and this permits the partitioning of their morphologic variability into components of within colony (i.e. within a single genotype) and between colony (i.e. between genotype) variance. These data have been obtained for four species of the endemic deep-sea genus Euginoma for a series of characters. In 8 comparisons, one component of the total variance dominated at the 5% level. Population (between colony) variance contributed significantly to the total variance in 63% of the comparisons (5 of 8); individual (within colony) variance contributed significantly to the total variance in 37% of the comparisons (3 of 8).Compared to shallow water species, the surprising feature of the deep-sea data is that the between colony component of variance is as high as it is. Possibly in the more stable, deep-sea environment, the genotypic contribution to the variance of each individual colony is expressed to a greater degree than in the more variable, shallow water regime. If so, then analyses of variability in colonial animals may be an independent means of ascertaining stability gradients in the fossil record.


2006 ◽  
Vol 86 (5) ◽  
pp. 1067-1081 ◽  
Author(s):  
N.M. Kilgallen ◽  
A.A. Myers ◽  
D. McGrath

A review of the shallow-water species of the genus Tryphosella from the British Isles is presented and a new species, Tryphosella lowryi, is described. In addition, Tryphosella minima is recorded from this region for the first time. This brings to five the total number of species of this genus now known from the British Isles. All taxa are fully described and illustrated, and a key to the species is provided.


Author(s):  
André Bispo ◽  
Monica Dorigo Correia ◽  
Eduardo Hajdu

Haliclonais an unusually species-rich genus in Porifera, with more than 400 species described. In spite of many subgenera used in the taxonomic housekeeping of these sponges, over half of them remain unassigned to a subgenus, thus encouraging a wide range of redescriptions and taxonomic revisions of materials from all around the world. In this paper, we describe two newHaliclonaspp. collected at Pernambuco, Alagoas and Bahia States (north-eastern Brazil, between 08°46′S and 13°56′S).Haliclona(Reniera)chlorillasp. nov. is a dark green or black coloured, delicately-branched species; andHaliclona(Soestella)peixinhoaesp. nov., a beige-coloured, tubular species, where tubes frequently bear large thorns and possess a conspicuous sub-superficial meandering reticulation. These species highlight the importance of includingex-situcollections in compiling baseline data, as both were already present in scientific collections by the 1980s and 1990s.


Zootaxa ◽  
2009 ◽  
Vol 2066 (1) ◽  
pp. 50-58
Author(s):  
KAREN SANAMYAN ◽  
DANIEL F. GLEASON

Four shallow-water species of colonial ascidians of the genus Aplidium are identified in the collections made by divers off the coast of Georgia, U.S.A. One of the specimens, Aplidium ruzickai n. sp., is characterized by a combination of high numbers of rows of stigmata and stomach folds and is described as a new species.


1976 ◽  
Vol 33 (8) ◽  
pp. 1667-1670 ◽  
Author(s):  
Irene Lubinsky

The shell morphology and area of distribution of Thyasira dunbari n.sp. is described and illustrated. This species differs from its northern relatives, especially T. gouldi Phil., by its high, bent forward shell, and thin, long edentulous hinge with massive callus. It occurs in the northernmost part of the Canadian archipelago and off East Greenland. It is a high arctic shallow-water species, which seems to be endemic in the Canadian–Greenlandic region.


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