Considerazioni su Lepton subtrigonum Fischer, de Folin & Périer ex Jeffreys ms., 1873 e Lepton lacerum Fischer, de Folin & Périer ex Jeffreys ms., 1873 (Bivalvia: Leptonidae).

• Autores: L. Giunchi, E. Rinaldi, C. Tabanelli, M. Tisselli
• Localización: Bollettino Malacologico, ISSN 0394-7149, Nº. 42, 5, 2006, págs. 85-91
• Idioma: italiano
• Texto completo no disponible (Saber más ...)
• Resumen
  • italiano

    Gli Autori segnalano la presenza di alcune valve riferibili a Lepton subtrigonum Fischer, de Folin & Périer ex Jeffreys ms., 1873 in tanatocenosi dell�Adriatico centro-settentrionale. Gli esemplari giovanili presentano due cuspidi poste ognuna su un lato dell�umbone: questo è un carattere mai segnalato per tale specie, mentre è un elemento diagnostico distintivo di Lepton lacerum Fischer, de Folin & Périer ex Jeffreys ms., 1873. Gli Autori ritengono che il materiale fossile pleistocenico determinato ed illustrato da Ruggieri (1967) come L.

    lacerum debba essere riferito ad esemplari giovanili di L. subtrigonum. Questo implica che L. lacerum non possa essere considerato un ospite nordico. Allo stato attuale delle cose, considerando l�esistenza di discrepanze tra le descrizioni e le figure originali delle due specie, nonché del fatto che il sintipo di L.

    lacerum sia andato perso, non è possibile stabilire se L. lacerum sia effettivamente una forma giovanile di L.

    subtrigonum oppure no. Questo problema potrà essere risolto solo grazie all�esame di materiale topotipico, attualmente non disponibile. Anche se Lepton subtrigonum non è stato finora trovato vivente in Mediterraneo, è presumibile, dati i nostri ritrovamenti, che la specie sia invece presente, almeno in Mar Adriatico.

  • English

    The analysis of three different thanatocoenoses from the North and the Middle Adriatic Sea lead to the finding of three loose valves and one complete specimen of a species that the AA ascribed to Lepton subtrigonum Fischer, de Folin & Périer ex Jeffreys ms., 1873 (Bivalvia: Leptonidae). The smaller valves show, on the dorsal margin laterally to the beak, two small spike-like projections, never noticed before on this species and apparently absent in larger specimens. These smaller valves well fit the description of Lepton lacerum Fischer, de Folin & Périer ex Jeffreys ms., 1873, as it was given by Ruggieri (1967).

    Originally, L. subtrigonum and L. lacerum have been described for the same type locality, the Southern Bay of Biscay. The AA reviewed the available literature about L. subtrigonum and L. lacerum. In particular, it emerged as the correct Author of both species is Fischer, de Folin & Périer, 1873, and not Jeffreys, since the drawings of both species given by Fischer, de Folin & Périer (1873) have to be considered a valid description, according to the ICZN art. 12.2.7. L. lacerum (sensu Ruggieri, 1967) has been reported for Italian fossil outcrops since lower Pleistocene and is currently considered a �northern guest�, while L.

    subtrigonum has been reported starting from Pliocene. After the literature review of past records and on the basis of morphological evidence, the Authors concluded that L. lacerum (sensu Ruggieri, 1967) is nothing but a juvenile of L. subtrigonum, which bears at its initial stages of life spike-like projections that became worn at a later stage of growth. This characteristic has also been noticed in other bivalves (e.g. Planktomya vanderlindeni Aartsen & Engl, 2001). Consequently, the taxon L. lacerum, sensu Ruggieri (1967), has to be regarded as synonym of L. subtrigonum and its purported status of �northern guest� cannot be retained anymore. Considering that the syntypes of L. lacerum have been lost and there is a mismatch between the descriptions and the original pictures of the two species, it is not yet possible to ascertain if the taxon L.

    lacerum is nothing but a juvenile of L. subtrigonum as well. To definitively solve this problem, more material from the type locality needs to be studied. Notwithstanding the fact that no living specimens of L.

    subtrigonum have been collected so far in the Mediterranean, from our findings it seems highly plausibile that this species could be found alive in the Adriatic Sea.