Order PETROMYZONTIFORMES

Museums

Museum list

Regional Maps

External Links

Order PETROMYZONTIFORMES

Compiler and date details

15 November 2011 - Douglass F. Hoese

Introduction

The order Petromyzontiformes previously comprised a single family of lampreys, Petromyzontidae (Nelson 1994; Paxton et al. 2006). However, Potter (1986) separated the Australian species into two separate families: Geotriidae and Mordaciidae. Gill et al. (2003) provided evidence for monophyly for Northern Hemisphere genera, but their phylogeny produced an unresulved trichotomy between the Northern Hemisphere group and the two Southern Hemisphere genera. Nevertheless they recommended separating the order into three families, the Northern Hemisphere Petromyzontidae and the Southern Hemisphere Geotriidae and Mordaciidae. Nelson (2006) and Gomon (2008) followed their recommendations. Kuratini & Kuratani (2006) provided molecular evidence of an early divergence for Geotria and Northern Hemisphere lampreys, but they did not examine Mordacia. They recognised the three groups as subfamilies. Consequently we follow the classification of Gill et al. (2003) and Renaud (2011), but recognise that further work is needed to resolve the classification.

Hubbs & Potter (1971) recognised 31 species in nine genera worldwide. Currently, however, 10 genera and 40 species are recorded (Nelson 2006): eight genera and 34 species in family Petromyzontinae; one genus and three species in Mordaciidae; and one genus and three species in Geotriidae. Three species in two genera have been recorded from Australia.

The world distribution of the group is antitropical: in the Northern Hemisphere above 30°N and in the Southern Hemisphere in South America, New Zealand and Australia south of 30°S. Many species are anadromous, spending part of their adult life at sea, where they attack other fishes, rasping away flesh with a toothed tongue. Other species do not migrate to sea and do not feed after metamorphosing to the adult stage. Like hagfishes, lampreys lack true jaws; the adults have a sucking oral disc on the head. Lampreys breed in freshwater streams and their filter-feeding larvae are known as ammocoetes. The maximum size is reached in parasitic species, some growing to 900 mm.

Potter & Strahan (1968), Strahan (1980) and Allen et al. (2002) reviewed the three Australian species. All are treated by Renaud (2011).