|The Atlantic Partridge Tun|
|By Harry G. Lee, M.D.|
One of the more unusual marine mollusk records for
northeast Florida waters is the occurrence of the Atlantic Partridge Tun. It is
one of a very few locally-collected species on which I personally have never
laid a hand, but documentation was secured by Charlotte Lloyd, who came across a
living specimen at a depth of 128 feet 45 miles east of Mayport on August 6,
1991. Being conservation-minded, yet wanting to placate skeptics of "(shell)fish stories," she chronicled the encounter on videotape just before releasing the
Aside from Charlotte's unusual coup, there is a bit more to say about this critter - partly its natural history, but more so the history of its naming. The unraveling of this paper trail took me through two and a half centuries of literature and provided a few general lessons in the sometimes complex process of taxonomic nomenclature.
The Atlantic Partridge Tun (see figure 1., a 40 mm. juvenile from Eleuthera, Bahamas in the Lee Collection), is widely known as Tonna maculosa (Dillwyn, 1817), a name proposed as "Buccinum perdix .... Variety ... Buccinum maculosum." on page 583 of volume 2 of this work (see bibliography for this and other citations). Lewis Weston Dillwyn recorded two references. The first was "Solander [actually Lightfoot, 1786 ] lot 3050 p. 136" [sic; error for 137]. In Lightfoot (1786) this entry reads "A very fine variety of Buccinum maculosum, S. or spotted Tun, undescribed from New Holland - very rare" [Lightfoot's italics]. The "S." connotes a name in a Daniel Solander manuscript - possibly only on the label appended to the specimen in question. Unfortunately the passage I quoted was all Lightfoot wrote; there is no cited illustration and insufficient text for this to stand as a validly-proposed taxon; ergo Buccinum maculosum Solander [Lightfoot, 1786] is a nomen nudum and unavailable for taxonomic nomenclature (International Code for Zoological Nomenclature (ICZN) Article 12; Criteria of Availability; see ref. below). How Dillwyn knew what Lightfoot had before him is uncertain, but he may have seen the actual shell, which was to have been sold at auction on Thursday May 25, 1786 according to the "Portland Catalog" (when Dillwyn was in his ninth year of life) at some point. Needless to say, the species is more than "very rare" in New Holland (Australia) as it does not live there.
Dillwyn's other (second) citation was Seba vol. 3, pl. 68, fig. 16 (see figure 2, taken from MŘsch, I., R. Willman, and J. Rust [eds]). Although the text of the non-binominal Seba work is not available for taxonomic nomenclature, this illustration almost certainly depicts the western Atlantic taxon in question - the editors' misidentification of it as Tonna perdix (Linnaeus, 1758) notwithstanding. Dillwyn was correct in recognizing his Buccinum maculosum as a new taxon! Unfortunately, however, a quarter century earlier Gmelin (1791, p. 3476, no. 22) applied that same binomen to a different shell, which we now know as the west African Cassis tessellata (Gmelin, 1791) [Buccinum tessellatum op. cit. p. 3476, no. 20]; see Abbott (1968; p. 54). The Dillwyn name is a primary junior homonym of Buccinum maculosum Gmelin, 1791 and therefore, until recently (see last paragraph), unavailable for taxonomic nomenclature according to the ICZN Article 52; Principle of Homonymy (ICZN, 1985).
Wait.... it gets more complicated! In looking further into the synonymy in Tucker's Cassis monograph (Abbott, 1968; p. 54), I saw that the binomen Buccinum maculosum was validly proposed by an even earlier authority, Thomas Martyn (1784)! Because Martyn's Universal Conchologist was not a consistently binominal work (like Seba), the International Commission for Zoological Nomenclature exercised its plenary powers (Anon., 1957) to declare most of Martyn's names invalid, while conserving the names applied therein to nine well-known New Zealand marine gastropod species. View The Nine Species Among these is Buccinum maculosum Martyn; now Cominella maculosa (Martyn, 1784). The consequence of this discovery is that B. maculosum Gmelin, like B. maculosum Dillwyn, would not be not available (primary junior homonymy, again; using ICZN, 1985). Since authors hadn't used B. maculosum Gmelin, quite possibly because it was reported as a junior synonym of B. tessellatum Gmelin by Dillwyn (1817; p. 596, no. 20), who appears to be the First Reviser (ICZN Article 24). It is possible that Dillwyn chose B. t. over B. m. because it appeared earlier in the Gmelin work (on the same page, two species above it, a convention referred to as "position priority," employed by some taxonomists in the past but never codified by ICZN) or perhaps because he thought the earlier Solander [Lightfoot] (nude) name rendered Gmelin's Buccinum maculosum unavailable. Whatever the machination, the outcome is that the cassid (helmet shell), unlike our tonnid (tun shell), nomenclature avoided being threatened with mass confusion by the loss of a such well-travelled binomen as Tonna maculosa (Dillwyn), the topic of this discussion.
Wait; there's still more. Helix sulphurea C. B. Adams, 1849 (p. 33) was first reported from Jamaica, and the author gave a short description, noted the size (0.175 inch across by 0.16 inch high), and stated; "Perhaps this is a young shell, but probably not of any described species." The next year he returned to this taxon and wrote (C. B. Adams, 1850; page 98): "On page 33 we described Helix sulphurea as 'perhaps a young shell.' This opinion was founded on its papyraceous appearance. Mr. Chitty, from whom the original specimens were received, has recently furnished a series, which shows that this shell, with all the generic characters of Helix, is the last embryonic stage of the West Indian variety of Dolium perdix!" [his exclamation point]. I believe figure 3. is very much like what C. B. Adams had before him in 1849 (and Chitty somewhat later). This is a photomicrograph of the apex of the same shell as in figure 1. It shows an intact ultraplanktotrophic protoconch reflecting a very long swimming veliger stage, an attribute which no doubt accounts for the wide dispersal of this species and many of its confamilial relatives. According to Clench and Turner (1950), the type specimen is lost, but, given the quotes above, I don't think anyone would dispute the diagnosis of Helix sulphurea C. B. Adams, 1849! As far as I can tell, the first reference to the synonymy of H. s. and Tonna maculosa Dillwyn, 1817 [sic; no parens] is Turner (1948; p. 169). But , once again, the bugaboo of junior homonymy creeps back into the picture; apparently unknown to Dr. Turner, the C.B. Adams name is preoccupied by Helix sulfurea Hombron and Jacquinot 1841 (p. 63: <http://www.biodiversitylibrary.org/item/110495#page/71/mode/1up>) from "Les ╬les Arrow" [Aru Islands in easternmost Indonesia near New Guinea], the subtle difference in spelling of the species epithet notwithstanding.
It appears the next available name for the Atlantic Partridge Tun is Dolium pennatum coined by the Danish conchologist Otto Andreas Lowson M°rch (he actually signed this work "M÷rch;" see below) from the "Antill." It was published in another public auction catalog - that of the Alphonso .... de Yoldi collection (its 4,012 lots rivaling the 4,156 of the Dutchess of Portland). M°rch's indication (lot 2058; p. 110) was an illustration in Martini - vol. 3, fig. 1078 (see figure 4). This is interesting because Martini himself called it a juvenile of Buccinum [now Tonna] perdix Linnaeus, 1758 and showed it alongside two adult T. perdix! Nonetheless this juvenile shell shows the color pattern of the W. Atlantic species (look at the smudgy pattern on the penultimate whorl in figure 1) - not the Indo-Pacific T. perdix, with which it seems to have been confused/associated by many authors. Ergo Tonna pennata (M°rch, 1852) refers to the Atlantic Partridge Tun, and the Partridge Tun, T. perdix (Linnaeus, 1758) from the Indo-Pacific is closely related - and not just biologically and by its vernacular name: Pennata probably means "feathered" in reference to its color pattern, which a century before likely inspired Linnaeus' perdix, Latin for "partridge."
Armed with all this
information about synonyms, homonyms, availability of nomina, etc., I was
getting ready to dismantle the underpinnings of the Atlantic Partridge Tun
nomenclature until a very perceptive correspondent of mine, Marien Faber
tactfully pointed out the value of "reading the directions" before launching
such an ambitious campaign. Marien indicated that the ICZN (1999;
fourth edition) contained an important policy change versus between the
third (1985) edition. Until 2000 a primary junior homonym (e.g., Buccinum
maculosum Gmelin, 1791; B. maculosum Dillwyn, 1817) was deemed
unavailable for taxonomic nomenclature (see end of
paragraph four) by the ICZN, and could only be conserved by petition to the
Commission to exercise its "plenary powers." The current (fourth; 1999) edition
states (Article 23.9.5): "When an author discovers that a species-group name in
use is a primary junior homonym of another species-group name also in use, but
the names apply to taxa not considered congeneric after 1899, the author must
not [our emphasis] automatically replace the junior homonym; the
case should be referred to the Commission for a ruling under the plenary power
and meanwhile prevailing usage of both names is to be maintained." Short
version: the burden of petition is shifted from authors who wish to conserve (a
majority of) primary junior homonyms to those authors who wish to suppress such
names. Ergo, until told otherwise, we are legit in using Tonna maculosa
(Dillwyn, 1817) as did the overwhelming majority of the authors who taught us
much of what we know of the Atlantic Partridge Tun.
Lady Margaret Cavendish Bentinck, Duchess of Portland, died in 1785 leaving
extensive and valuable collections, not the least of which was of shells. The
Rev. John Lightfoot (1735-1788), her librarian and chaplain, compiled and
annotated a list of her curios. This 194 page, 4,156 lot inventory was printed
early the next year and served as the catalogue at the auction of her
collections conducted from late that May to June 18 (Lightfoot, 1786; Dance,
1966; Kay, 1965; Rehder, 1967). Allison Kay (1965; p. 10) gave convincing
evidence that Daniel Solander, a pupil of Carl Linnaeus (in 1761 ennobled as
Carl von LinnÚ), a naturalist who curated material in the collection of the
Duchess, first penned many of the names employed by Lightfoot, but only in
form. Until 1965 most attributions for the "Portland Catalogue" nomina
were to Solander, but, after Kay's report, the consensus among malacologists is
Although a substantial number of zoological names were validly proposed by
Lightfoot in this "Portland Catalogue," only a handful of workers in the 18th
and 19th centuries put them to use, often without proper
acknowledgment. Even the work of Sherborn (1902; later corrected), which purported to list all
the zoological names introduced from 1758 to 1800, listed none of these names.
Tom Iredale (1912)
was the first to specifically wrest the names from near oblivion. William
Healy Dall (1921) investigated the "Portland Catalogue" mollusks and presented
selections of the Lightfoot text, which was always brief, but often cited an
illustration in an earlier work or two. A more exhaustive and definitive
treatment was provided by Rehder (1967), who edited out 15 species names as
nomina nuda (nude names) due to lack of rigorous descriptions or cited
illustration(s). The author added five molluscan species names overlooked by
Dall and proceeded to pare the total (111) as follows: 39 junior synonyms
(species validly named prior to the "Catalogue"); three junior homonyms (names
selected by Lightfoot but used by prior authors); nine nomina dubia
(descriptions and illustrations insufficient to diagnose the species) and three
nomina oblita (forgotten names not employed in the literature between
1917 and 1967): Voluta incompta, Mytilus castaneus, and Helix
This action was not consistent with the provisions of the second edition of the
Code (ICZN, 1964: 24, Article 23b), which required a petition to the Commission
for such suppression. Inasmuch as none of these three taxa had been placed on
the Official Lists two decades after Rehder's work (Melville and Smith,
1987), the names are very likely still available. Only the first, now placed in
Mitra, is recognizable and valid; the other two are considered available
but nomina dubia.
These machinations produce 56
available valid species-level
and two generic names for Recent mollusks attributable to The Rev. John
Lightfoot. Rehder's systematic list at the end of his paper omitted the valid
Subninella undulata and Strombus sinuatus, which were given proper
(and favorable) treatment in the text,
Voluta incompta discussed above.
An Emended List
Lately revisionists (including Turgeon, Quinn, et al., 1998, who also exalted Tonna pennata over T. maculosa) have worked hard to render vernacular names in lower case. For a rebuttal see Freaky Flatcoils.
Also see: Tonna pennata Atlantic