Parthena acutangula (Burrow, 1815)

 Parthena acutangula (Burrow, 1815)

El Yunque Rain Forest, northeastern Puerto Rico, September, 2010 (42 mm). Collected by Alan Gettleman.


This species is the (mono)type of Parthena Albers (1850: 112) by the subsequent designation of Pilsbry (1894: 98-99).

This nominal taxon represents an instance in which two authors independently bestowed the same name on a species each considered new to science, to wit Helix angulata Burrow (1815: pl. 26, fig. 1) and Helix angulata Férussac (1822: plate 61, fig. 3*). However, Burrow spelled the species epithet "acutangula" in the text (p. 183,), and the first reviser chose that spelling as correct. Because the biological taxa are considered synonymous, one or the other Burrow name would have precedence (validity) pursuant to the Principle of Priority. However, the fixation of the correct original spelling protects Helix angulata Férussac 1822 from an additional indignity, junior homonymy, which would render it permanently invalid.

* plate 61 appeared in Livraison 16 of the serially-issued Histoire naturelle générale et particulière des mollusques terrestres et fluviatiles ..., published on 16 July 1822 without captions, as were the others therein. The corresponding plate explanations did not appear until months later, on 2 November in Livraison 17 (Kennard, 1942: 110). Only at that point did the names for the new species depicted become available for formal taxonomic nomenclature. A full bibliographic citation, as well as URL's to online versions and more detailed collations of this masterwork appear at [http://www.jaxshells.org/blau.htm].


Burrow, E.I., 1815. Elements of conchology, according to the Linnæan system, illustrated by 28 plates, drawn from nature [1st edition]. R. & A. Taylor, London. xix + 246 pp.

Kennard, A.S., 1942 The Histoire and Prodrome of Férussac. Proceedings of the Malacological Society of London 25(3): 105-110. 18 December. [vidi; not on-line].

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