Mordacia praecox Potter, 1968
Non-parasitic lamprey
photo by FAO

Family:  Mordaciidae (Southern topeyed lampreys)
Max. size:  50 cm SL (male/unsexed)
Environment:  demersal; freshwater, potamodromous
Distribution:  Oceania: known only from the Moruya and Tuross Rivers in southern New South Wales, Australia.
Diagnosis:  Adults: 10.2-172 mm TL; body proportions, as percentage of TL: 9.4-12.6 prebranchial length, 8.2-9.9 branchial length, 59.6-64.2 trunk length, 16.5-20.4 tail length, 1.3-1.5 eye length and 5.4-8.4 disc length; no gular pouch develops; urogenital papilla not prominent in mature adults; trunk myomeres, 85-93. Adult dentition: 2 triangular supraoral laminae each with 3 unicuspid teeth, 1 per apex (exceptionally, 4 unicuspid teeth per supraoral lamina); Infraoral lamina, 9-10 unicuspid teeth of various size (these teeth become greatly enlarged with sexual maturation); 5-6 endolaterals on each side; endolateral formula, typically 2-2-3-3-4-3 or 2-2-3-3-4-4 in immature individuals and 1-1-1-1-1 or 1-1-1-1-1-1 in mature individuals; 1 row of anterials; first row of anterials, 2 unicuspid teeth flanked on either side by one bicuspid tooth in immature individuals and 4 unicuspid teeth in mature individuals; 1-2 rows of exolaterals on each side; 1 row of posterials; first row of posterials, 16 posterial plates, the three lateralmost tricuspid and the internal ones bicuspid in immature individuals and 13 unicuspid teeth in mature individuals; transverse lingual lamina w-shaped with numerous unicuspid teeth of various size, the middle apex one being intermediate in size and the two bottom apex ones being largest, while the rest are small; longitudinal lingual laminae hook-shaped each with an undetermined number of unicuspid teeth. Body coloration (live) of mature adults with dark blue dorsal surface, occasionally with a green tinge, ventral surface of males mottled gray and ventral surface of females yellowish; extent of caudal fin pigmentation, 25% to <75%; caudal fin shape, spade-like; oral papillae, 33-48 (Ref. 89241).
Biology:  Inhabits freshwater streams, a non-parasitic lamprey that spends its entire life cycle in freshwater. Ammocoetes burrow in soft substrates, phase lasts about 3 years; metamorphosis usually occurs between October and November. Presumed to migrate upstream around April, and spawns in late winter or spring (Ref. 44894). Fecundity, 326-675 eggs/female (Ref. 89241).
IUCN Red List Status: Endangered (EN); Date assessed: 04 February 2019 (A2b; B2ab(v)) Ref. (130435)
Threat to humans:  harmless


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