Definition: A taxon is Least Concern when it has been evaluated against the criteria and does not qualify for Critically Endangered, Endangered, Vulnerable or Near Threatened. Widespread and abundant taxa are included in this category.
Comment: "Large" is ambiguous. For details on "Large rivers" (e.g. the Mekong river) see http://worldwildlife.org/biomes/large-river-ecosystems This class will be replaced with a less ambiguous class.
Comment: "Small" is ambiguous. For details on "Small rivers" (e.g. the Salween river) see http://worldwildlife.org/biomes/small-river-ecosystems. This class will be replaced with a less ambiguous class.
Definition: Gravel is an environmental material which is composed of pieces of rock that are at least two millimeters (2mm) in its largest dimension and no more than 75 millimeters.
Definition: National Museum of Natural History, Smithsonian Institution (USNM), Washington, District of Columbia, USA.\r\nNMNH and USNM both refer to the National Museum of Natural History. Collections are associated with one or the other acronym. US, the US National Herbarium, is a collection within the National Museum of Natural History. URL for main institutional website, http://www.mnh.si.edu/rc/\r\nURL for institutional specimen catalog, http://collections.mnh.si.edu/
