Classification / Names
Common names | Synonyms | Catalog of Fishes(genus, species) | ITIS | CoL | WoRMS | Cloffa
Petromyzonti (lampreys) > Petromyzontiformes
(Lampreys) > Geotriidae
Etymology: Geotria: Etymology not explained, although three possibilities, all problematical, have been proposed: (1) from the Greek geotragia, “eating of earth-like substances,” referring to how this lamprey, like other lampreys, uses its suctorial mouth to attach itself to submerged rocks and stones, thus creating the impression that it is feeding on the earth (problem: geotragia does not mean “earthy,” as in rocks and minerals, but “products of the earth,” such as grains and vegetables; (2) geo- (Gr.), earth, and atrium (L.), room, referring to this lamprey’s nest, presumably made of stones and pebbles assembled by one or both parents (problem: nest-building, while known in other river lampreys, was probably not known to Gray in 1851 and has not been documented for this species); (3) a variation of #2, proposed by Meagher (2010), referring to its discovery in underground chambers, in which it survives dry periods (problem: G. australis does not, nor does any other lamprey, aestivate, nor did Gray indicate it was discovered underground, although he did speculate whether the pouch was an adaptation to the “long drought of the Australian rivers”). See EthyFish.org for more details. (See ETYFish); macrostoma: macro-, from makros (Gr.), large; stoma (Gr.), mouth (but used here as an adjective, mouthed), presumably referring to greatly expanded oral disc of spawning adults. (See ETYFish).
Environment: milieu / climate zone / depth range / distribution range
Freshwater; brackish; demersal; unknown. Temperate
Countries | FAO areas | Ecosystems | Occurrences | Point map | Introductions | Faunafri
South America and Southwest Atlantic Islands: De la Plata River, Uruguay; de la Plata
River to Tierra del Fuego, Argentina; Malvinas (Falkland) Islands, South Georgia. One record in a river tributary of Magellan Strait in Chile.
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Previously synonymized with Geotria australis Gray, 1851. The taxonomic revision remains to be done (as of Nov. 2021), so little is known about this species but its morphology.
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Firpo Lacoste, F., L. Fernández and C. Scioscia, 2021. On an unknown lamprey holotype (Petromyzon macrostomus Burmeister 1868) and the genus Exomegas Gill 1883 from South America. J. Fish Biol. 99(4):1507-1512. (Ref. 125540)
IUCN Red List Status (Ref. 125652)
CountriesFAO areasEcosystemsOccurrencesIntroductionsStocksEcologyDietFood itemsFood consumptionRation
Common namesSynonymsMetabolismPredatorsEcotoxicologyReproductionMaturitySpawningSpawning aggregationFecundityEggsEgg development
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingNutrientsMass conversion
Estimates based on models
Phylogenetic diversity index (Ref. 82805
= No PD50 data [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00102 (0.00046 - 0.00225), b=3.06 (2.88 - 3.24), in cm total length, based on all LWR estimates for this BS (Ref. 93245
Trophic level (Ref. 69278
): 4.5 ±0.8 se; based on size and trophs of closest relatives
Fishing Vulnerability (Ref. 59153
): Moderate vulnerability (43 of 100) .
Climate Vulnerability (Ref. 125649
): (0 of 100) .