The systematics of British larval lampreys

Abstract

Several taxonomic characters, including the number of trunk myomeres, proportional body measurements and patterns of external and internal pigmentation, have been investigated in populations of ammocoetes belonging to the three species of lampreys found in British rivers. Petromyzon marinus can be readily distinguished by the pigmentary pattern in the tail and on the oral hood, and by the much higher number of trunk myomeres. Although no character can be used to separate with certainty the larvae of Lampetra fluviatilis and Lampetra planeri, significant differences were found between the mean number of trunk myomeres in the two species. Moreover, the values for ammocoetes were virtually identical to those of the respective post‐larval stages, at which phase in the life cycle the two Lampetra species are clearly distinguishable. The incidence of pigmentation on the tongue precursor was much higher in larval populations of L. fluviatilis than in those of L. planeri and there was also a difference in the rate of change in the relative length of the trunk and tail. Where comparisons can be made, the results in this paper are in agreement with those of most other European and North American workers. The data differ markedly, however, from that contained in the only other previous detailed systematic study on British larval lampreys, which was subsequently used as the basis for taxonomic keys.

Three new cryptic species of the lamprey genus Lampetra Bonnaterre, 1788 (Petromyzontiformes: Petromyzontidae) from the Iberian Peninsula

“…The number of trunk myomeres was significantly different between populations, but there was overlap. The numbers observed in our study are within the limits reported for L. planeri by Potter and Osborne (1975), who compared data from different parts of Europe. A progressively greater number of trunk myomeres was found to the north, a pattern which has been previously observed in other lamprey species (e.g.…”

Potential Impacts of Small‐scale Hydroelectric Power Generation on Downstream Moving Lampreys

“…Eight canal net samples were taken by day and 19 by night. All captured ammocoetes, transformers, and adults were identified (Potter and Osborne, ; Gardiner, ) and measured under anaesthesia (MS‐222, 0.1 g L ‐1 ) and allowed to recover fully before being returned to the river. Because L. planeri and L. fluviatilis cannot be distinguished externally at the ammocoete stage, they were recorded as Lampetra sp.…”

From shallow to deep waters: habitats used by larval lampreys (genus Petromyzon and Lampetra) over a western European basin

“…Larvae were anesthetized with Eugenol (Chanseau et al 2002) and their total length was measured (±0.1 mm). For the larger specimens, tail pigmentation was used to distinguish P. marinus from Lampetra spp., using the keys of Potter & Osborne (1975) and Bird & Potter (1979). A genotyping test was used to distinguish between smallest specimens (Taverny et al 2005).…”