The largetooth sawfish (Pristis microdon), also known as the Leichhardt's sawfish or freshwater sawfish, is a sawfish of the family Pristidae, found in shallow Indo-West Pacific oceans between latitudes 11° N and 39° S. As its relatives, it also enters freshwater. This critically endangered species reaches a length of up to 7 metres (23 ft). Reproduction is ovoviviparous. Recent evidence strongly suggests P. microdon is synonymous with P. pristis.
Considerable taxonomic confusion has surrounded this species. It is part of the Pristis pristis species complex, which also includes P. perotteti. P. microdon has sometimes been considered synonymous with P. perotteti, and uncertainty exists over what species the scientific name P. microdon really belong to (the original description lacked a type locality).
Recent evidence strongly suggests the three are conspecific (in which case P. microdon and P. perotteti are synonyms of P. pristis), as morphological and genetic differences are lacking. Three main clades based on NADH-2 genes were evident (Atlantic, Indo-West Pacific, and East Pacific), but these do not match the distributions claimed for P. pristis (circumtropical), P. microdon (Indo-West Pacific) and P. perotteti (Atlantic and East Pacific) respectively.
The largetooth sawfish is a heavy-bodied sawfish with a short massive saw which is broad-based, strongly tapering and with 14 to 22 very large teeth on each side - the space between the last two saw-teeth on the sides are less than twice the space between the first two teeth. The pectoral fins are high and angular, the first dorsal fin being mostly in front of the pelvic fins, and the caudal fin has a pronounced lower lobe.
The largetooth sawfish was listed as endangered in the United States under the Endangered Species Act in 2011. In December 2014 the U.S. listed the widest taxonomic definition of largetooth sawfish (including P. perotteti and P. microdon) as endangered.
- Faria, V. V.; McDavitt, M. T.; Charvet, P.; Wiley, T. R.; Simpfendorfer, C. A.; Naylor, G. J. P. (2013). Species delineation and global population structure of Critically Endangered sawfishes (Pristidae). Zoological Journal of the Linnean Society 167: 136–164. doi:10.1111/j.1096-3642.2012.00872.x Retrieved 26 August 2013.
- NMFS. Endangered and Threatened Wildlife and Plants; Endangered Status for the Largetooth Sawfish.Federal Register;; v72, (July 12, 2011), 40822-40836.
- NMFS. Endangered and Threatened Wildlife and Plants; Final Endangered Listing of Five Species of Sawfish Under the Endangered Species Act.Federal Register;; v79, (December 12, 2014), 73977-74005.
- Froese, Rainer and Pauly, Daniel, eds. (2009). "Pristis microdon" in FishBase. October 2009 version.