Much of the material in limestone is derived from the break-up of the calcareous hard parts of organisms such as clam shells and coral sticks, and more is derived from the erosion of previously deposited muds. Such minerals are rich in the element silicon, so they are referred to as silicates, but even most limestones consist largely of fragments of pre-existing carbonate materials. Sandstones, for example, consist largely of quartz, feldspar, and fragments of other minerals typically found in granites and the other types of bedrock that make up our continents. Most types of sand are created through the breakdown of pre-existing rocks and crystals. Most ooids consist of the chemical compound CaCO3 (calcium carbonate), so most oolites belong to the group of rocks known as LIMESTONES. The unusual name reflects the fact that grains of oolitic sand are highly reminiscent of fish eggs or roe when examined closely. After they have been buried under additional sediment, such sand grains can be fused into a solid mass of sedimentary rock known as an OOLITE. 2015] Morphological Characteristics a.OOIDS are a distinctive type of sand that usually form on the sea floor.2016] Genome-Culture Coevolution promo.2015] New Species of the Genus Cleisosto.2016] Polyceratocarpus askhambryan-iring.2016] The Andean Paepalanthus pilosus co.The latter genus now includes the two new species P. Chriolepis fisheri is considered incertae sedis, as its phylogenetic position is either sister to Pinnichthys, or nested within Psilotris.

The new genus Paedovaricus is erected for Paedovaricus imswe (formerly Varicus imswe), and the new genus Carrigobius is erected for Carrigobius amblyrhynchus (formerly Psilotris amblyrhynchus). nov., and also contains three other species formerly included in Chriolepis ( C. The genus Pinnichthys is erected for the new species Pinnichthys aimoriensis gen. benthonis) are now reassigned to the genus Varicus, which now also contains five new species described here ( Varicus adamsi sp. Two Atlantic species previously belonging to Chriolepis ( C. We synonymize the genus Pycnomma with Chriolepis. Lastly, we provide a key to all named species of the Nes subgroup along with photographs and illustrations to aid in identification.īased on our combined analysis of molecular data from mtDNA, nuclear genes, and morphological characters, we have made the following changes in the classification of the Nes subgroup in order to render all groups monophyletic (see Table 2). nov., Chriolepis, Eleotrica, Gobulus, Gymneleotris, Nes, Paedovaricus gen. The group now contains 38 species in the genera Carrigobius gen.

The new classification includes four new genera and nine new species described here, many of which were collected from rarely sampled deep Caribbean reefs using manned submersibles. We present a new classification for the group in which all genera are monophyletic and in most cases diagnosed by combinations of morphological characters. Our results indicate that all of the characters previously used to diagnose genera of the Nes subgroup display some degree of homoplasy with respect to our molecular tree however, many characters display considerable phylogenetic signal and thus may be useful in diagnosing genera when used in combination with other characters.

We then evaluate the congruence between the distribution of morphological characters and our molecular tree using maximum-likelihood ancestral state reconstruction, and test for phylogenetic signal in characters using Pagel's λ tree transformations (Nature, 401, 1999 and 877). Here we present the most comprehensive phylogeny to date of the Nes subgroup using mitochondrial and nuclear sequence data. This may be particularly true for the Nes subgroup of gobies, where several genera that are diagnosed by ‘reductive characters’ have been shown to be polyphyletic. It has been suggested that morphological characters in gobies tend to evolve via reduction and loss associated with miniaturization, and this, coupled with the parallel evolution of adaptations to similar microhabitats, may lead to homoplasy and ultimately obscure our ability to discern phylogenetic relationships using morphological characters alone. The Nes subgroup of the Gobiosomatini (Teleostei: Gobiiformes: Gobiidae) is an ecologically diverse clade of fishes endemic to the tropical western Atlantic and eastern Pacific oceans.

Oolite sedimentary rock