Posted: Sep 22 2007

 Laevicardium serratum (Linnaeus, 1758), Common Egg Cockle

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laevicardium pictum 4.jpg
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Click on these two slides to see species presentations:

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laevicardium pictum 3.jpg

Posted on LTS forum by Harry Lee, Aug 12 2009:


Vidal (1999: 327) examined the types of Cardium laevigatum Linnaeus, 1758 and designated a lectotype, which he considered synonymous with the Indo-West Pacific Fulvia papyracea (Bruguière, 1789). He also established a lectotype for C. serratum Linnaeus, 1758 from the same (Linnean) collection. The latter [now Laevicardium serratum (Linnaeus, 1758)] is the valid name for the Caribbean Laevicardium laevigatum of authors (e.g., Abbott, 1974 and Hartman, 2006).

Vidal, J., 1999. Taxonomic review of the elongated cockles: genera Trachycardium, Vasticardium and Acrosterigma (Mollusca, Cardiidae). Zoosystema 21(2): 259-335.

Marlo:

Here is my interpretation of Harry's comments based upon my understanding of the terminology.

Linnaeus had a group of shells all of which he considered to be the same species. He assigned the name Cardium laevigatum Linnaeus, 1758 for all the shells in the group, but did not designate a single shell from the group as a holotype. When this is done the shells in the group are called syntypes (sometimes referred to as the type series). Vidal examined Linnaeus' type series and determined that more than one species was involved. So, he separated them into species groups. One group he determined best fit Linnaeus' description for Cardium laevigatum. From this group he selected one shell to represent Cardium laevigatum. When an author names a species based upon a group of shells (syntypes), as Linnaeus did, and a later author designates one of the syntypes to represent the species, as Vidal did, that selected shell is called a lectotype.

Vidal then found that one of the other species groups he had separated matched other shells Linnaeus had named Cardium serratum and for which Linnaeus had not designated a holotype, which meant all the shells in Linnaeus' collection of this name were syntypes. So, Vidal designated one of these shells to represent the species, thus creating a lectotype for Cardium serratum, which at present is classified as belonging to the genus Laevicardium, and should properly be labeled as Laevicardium serratum (Linnaeus, 1758).

So, assuming Vidal's work is valid, and until such time as another writer finds a basis to again change the classification of this shell, as Harry points out, we need to change the name on the shells in our collections we previously labeled as Laevicardium laevigatum.

Harry:

Not exactly. According to Vidal (1999: 327) he found three single valves (syntypes) labelled Cardium serratum in the Linnean Collection, London. These "belong undoubtedly to the American Atlantic Laevicardium laevigatum" as treated in Johnsonia. The largest, a left valve, bore the hand marked numbers of Linnaeus: 73 and 89, which are the species numbers for C. serratum in the author's 1758 and 1767 works. That marked shell was designated the lectotype of C. serratum by Vidal.

As for Cardium laevigatum Linnaeus, Vidal found "two bivalved" shells" and a single valve (all syntypes) thus labelled. The two pairs belong to the species recently known as Fulvia papyracea (Bruguière, 1789) and the single valve to "Fulvia australis (Sowerby, 1834)." The larger of the two pairs was similarly marked (88; the no. for that nominal taxon in the 1767 work), and this pair was named the lectotype for Cardium laevigatum Linnaeus, which is a senior synonym of Fulvia papyracea (Bruguière, 1789).

The centuries-old problem with the interpretation of these Linnean species stems from the ambiguity and heterogeneity of figures cited by Linnaeus in 1758. Vidal's solution is compelling, and it appears to be the soundest basis for identifying these two taxa, the identity of which was mistaken not only in Johnsonia but by every 20th Century work (save Vidal) dealing with one and/or the other taxon.

Linnaeus, C., 1758. Systema naturae per regna tria naturae, secundum classes, ordines, genera, species cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata. Laurentius Salvius, Holmia (Stockholm). Pp. 1-823 + i. [Original work not seen; reprinted in facsimile by the British Museum of Natural History, London, 1956 (+ v).] On-line at Caroli Linnæi ó. Systema naturæ 1758.

Linné. C. von, 1767. Systema naturae, seu per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus II Editio duodecima, reformata. Laurentius Salvius, Holmia (Stockholm). Pp. 533-1327. On-line at Caroli a Linné... systema naturae 1767.

rfai:

Apparently, WoRMS now considers the species to be Fulvia laevigata (Linnaeus, 1758). What's a shell collector to do?

Citation: ter Poorten, J.; Rosenberg, G. (2014). Fulvia laevigata (Linnaeus, 1758). Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=t...tails&id=605734 on 2014-11-25.

Harry:

Nope; Fulvia laevigata (Linnaeus, 1758) is Indo-Pacfic, and Laevicardium serratum (Linnaeus, 1758) is Western Atlantic.

The two genera are quite distinct.

WoRMS formatting takes some getting used to.