Comments on the proposed conservation of usage of Testudo gigantea Schweigger, 1812 (currently Geochelone (Aldabrachelys) gigantea) (Reptilia, Testudines) 3 (Case 3463)

Publication Type:Journal Article
Year of Publication:2010
Authors:Bour, R, Pritchard, PCH, Iverson, JB
Journal:Bulletin of Zoological Nomenclature
Volume:67
Issue:1
Start Page:73
Pagination:73-78
Date Published:03/2010
Type of Article:Comment
ISSN:0007-5167
Full Text

The present statement is proposed in order to establish definitely on which bases the
valid scientific name of the Aldabra tortoise rests. We specifically address the five
major points of contention which were disputed in the previous comments about this
case published in this journal (BZN, 66(1), 66(2) and 66(3)). We claim to be
professional taxonomists of some experience and we aspire to take into account only
factual, objective data. The articles and recommendations of the International Code
of Zoological Nomenclature presently in force, here the ‘Code’, are followed. The
colleagues who claim they refuse to make the adjustment of giving up the name
gigantea for the Aldabra tortoise need to agree that, for 200 years, many changes
were implemented in the phylogenetic and taxonomic appraisal of the group of
tortoises at stake. ‘Comfort levels’ are not pertinent to the case at hand, and emotion
and personal preference are not the criteria by which the case should be judged.The quality of Schweigger’s diagnoses and descriptions is poor
The work of Schweigger (1812) is based on actual specimens, and includes measurements
for the new species. It is without any doubt the best of its epoch. At that time,
other similar works were mainly founded on previous publications and on more or
less literary sources. If Schweigger’s descriptions are deemed inadequate, then all
descriptions prior to at least Duméril & Bibron (1835) could be called into question.
Schweigger mainly worked with the collections of the Paris Museum (MNHN), and
presently the type specimens of 14 distinct species described by this author have been
identified in this institution, thanks to the accuracy of the publication (see Bour,
2008b). We wonder who among the authors of the published comments have directly
read and/or translated the original Latin description, and who among those who have
questioned the rediscovery have actually seen the types of any of these early names.
Unfortunately, this case is not an isolated one. We predict that future morphological
and molecular analysis of type material will show that many names have been
misapplied or misunderstood in the past.
The holotype of Testudo gigantea Schweigger, 1812 was ‘lost’ for nearly two centuries
In fact this holotype was misplaced and wrongly identified for a long time. The
specimen was also studied and measured by Duméril & Bibron (1835), who did not
recognise it as being the ‘type’ of this species. A careful reading of their opus reveals
several other similar misinterpretations, but such an exposition is beyond this note.
The recent rediscovery of the type of T. gigantea in the MNHN is used by some as
argument against our proposition, but we will not debate the defamatory insinuation
of a timely rediscovery, like ‘rediscovered just when it was supportive for their point
of view’. Actually this is not unusual, especially given that few modern chelonian
researchers deem the examination of type material as essential to systematic study.
We can give several references of recent ‘rediscoveries’ of type specimens: Iverson &
McCord (1989) for Emys muticus Cantor, 1842; Pritchard (1996) for Testudo
ephippium Günther, 1875; Bour & Maran (1998) for Emys leprosa Schweigger, 1812;
Bour (2008a) for Testudo angulata Schweigger, 1812; Rhodin & Carr (2009) for
Testudo scripta Schoepff, 1792. In some cases, these discoveries challenged the
‘accepted’ nomenclature: that is science and science recognises change; if not, it is no
longer science, it is dogma.This is not the holotype of Testudo gigantea
Bour (2006) has extensively studied each of the details provided in the description(s)
of Testudo gigantea Schweigger, 1812, which led to the recognition that MNHN
9554, long identified as Chelonoidis denticulata (Linnaeus, 1766), a yellow-foot
tortoise, is undoubtedly the holotype. But who really understands the diagnostic
value of ‘testa cylindracea . . . pedes squamis robustis, latissimis robusti . . . marginis
viginti tres, aequalis’? Actually, among all known chelonians, a large and elongated
tortoise with large scutes on the forearms, no cervical (nuchal) scute, and rounded
flanks could only apply alternatively to a Mascarene tortoise (genus Cylindraspis);
but the origin of the specimen (Brazil, via Lisbon) removes any doubt. It must be
explained here that the MNHN collections have gone through a period of disorganisation
from 1965 to the opening in 1994 of the ‘Zoothèque’, an underground storagebuilding. Several comments allude to a deficient original description, but none of
them has provided any precise character that would support a refutation of the
identity of the type of T. gigantea; they have simply rejected our interpretation.
Moreover, no person among the detractors has asked either to examine the specimen,
nor for pictures of it. Finally, we will just mention again one measurement: the
holotype of Testudo gigantea had a curved length of 767 mm according to
Schweigger; the large specimen of C. denticulata measured by Duméril & Bibron had
a curved length of 770 mm; and the ‘rediscovered’ specimen of C. denticulata
(MNHN 9554) has a curved length of 770 mm. Sometimes numbers are more
eloquent than a long description.
The neotype designation is the solution
We here strictly quote the Code, precisely the relevant parts of Article 75.3. A valid
neotype is designated when the designation is published with the following particulars:
‘75.3.4. the author’s reasons for believing the name-bearing type specimen(s) (i.e.
holotype, or lectotype, or all syntypes, or prior neotype) to be lost or destroyed, and
the steps that had been taken to trace it or them’. Such mandatory statements are
completely wanting in Frazier’s (2006a) paper.
‘75.3.5. evidence that the neotype is consistent with what is known of the former
name-bearing type from the original description and from other sources’. This point
was already raised by Bour (2006), who noted these differences between the neotype
and the holotype: ‘e.g. absence vs. presence of a cervical scute; limbs shielded by
tough and very broad scales vs. only postcranial skeleton, and fragments of skin’; we
can also add: a full specimen (head, limbs, tail are described) vs. a shell.
‘75.3.6. evidence that the neotype came as nearly as practicable from the original
type locality [Art. 76.1] and, where relevant, from the same geological horizon or host
species as the original name-bearing type’. The neotype came from Aldabra, the
holotype from Brasil, unless someone can demonstrate that the latter is wrong.
‘Recommendation 75B. Consultation with specialists. Before designating a neotype,
an author should be satisfied that the proposed designation does not arouse
serious objection from other specialists in the group in question’. Nothing was
submitted at least to the present authors or to Justin Gerlach, who are among the
taxonomists who recently published the most extensively on the systematics of these
tortoises.
Finally, according to Article 75.8, a holotype always out-trumps a neotype: ‘If,
after the designation of a neotype, the name-bearing type (holotype, syntypes,
lectotype or previous neotype) of the nominal species-group taxon that was (were)
presumed lost is (are) found still to exist, on publication of that discovery the
rediscovered material again becomes the name-bearing type and the neotype is set
aside . . .’. The only conclusion is that the neotype designation is both unnecessary
and unacceptable.
The stability stands with the name T. gigantea Schweigger, 1812
Beside the rebuttal of the identity of the type specimen of T. gigantea, a major
expressed argument is the stability of the name in connection with the Aldabratortoise. First, we note that the most recent (1982–2006) 36 names (nominal
combinations) for the Aldabra tortoise, as listed by Fritz and Havaš (2007), only
include a single combination that contains the word gigantea. Second, in order to
have an idea about the respective importance of the main combinations used to name
the Aldabra tortoise, and the involved genera, we used ‘Google’ data, i.e. a procedure
which can be reproduced by anyone, but whose results may be very volatile, as
developed below. We limited our research to the species T. gigantea Schweigger,
1812, T. dussumieri Gray, 1831, and T. elephantina Duméril & Bibron, 1835. The
results (updated on 22 October 2009) are the following:
Combination used Occurrence % of subset
Testudo gigantea 8130 85.1
Testudo elephantina 1290 13.5
Testudo dussumieri 136 1.4
Geochelone gigantea 12500 91.6
Geochelone elephantina 71 0.5
Geochelone dussumieri 1080 7.9
Aldabrachelys gigantea 4130 38.5
Aldabrachelys elephantina 6360 59.3
Aldabrachelys dussumieri 234 2.2
Dipsochelys gigantea 255 1.3
Dipsochelys elephantina 2250 11.2
Dipsochelys dussumieri 17600 87.5
Aldabrachelys (alone or combined) 13700 16.8
Dipsochelys (alone or combined) 67900 83.2
TOTAL gigantea 25015 46.3
TOTAL elephantina 9971 18.5
TOTAL dussumieri 19050 35.3
These data reveal that an agreement on usage for the species or the genus names
does not exist. Actually these figures are continually moving and they obviously
reflect a drift, rather than providing an absolute amount. On 1 August 2009 the
number of returns for Aldabrachelys was 9510, for Dipsochelys 88100; as shown
above, on 22 October (when this paper was submitted for publication) this number
was 13700 for Aldabrachelys, 67900 for Dipsochelys; finally, on 28 December (a
corrective was sent to the editor) this number was 23200 for Aldabrachelys,
decreasing to 52700 for Dipsochelys. Moreover, within two months some references
have overwhelmingly increased: Testudo elephantina from 1290 to 5300, Testudo
dussumieri from 136 to 13800, Testudo gigantea from 8130 to 91200! These figures
greatly confirm that ‘Google’ numerical data, if applied for more than a brief period,
should be used and interpreted with caution, as already underlined by Dubois (2007)
and repeated by Frost et al. (2009). In fact, it could be argued that only figures
obtained prior to the raising of the case by Frazier (2006a) should be considered, as
they were not biased by the debate (see in this respect Dubois, 1997: 319). We must
also note that the title of the Case in the ICZN Bulletin was itself biased, including
‘Currently Geochelone (Aldabrachelys) gigantea’, despite a request by one of us
(PCHP). This combination only returned 76 ‘hits’.
Presently, all mentions of gigantea (including Testudo gigantea, which is obviously
an outdated combination, used by non-taxonomists) added together show that it isthe most used species epithet by only a moderate margin (46.3% vs. 35.3% for
dussumieri). On the other hand, the most used combination is Dipsochelys dussumieri:
17600 returns vs. 12500 for Geochelone gigantea (58.5% vs. 41.5%). However, it is
clearly evident that there is no consensus, no established name, i.e., there is not
current stability, contrary to the allegations of many comments and of the title of the
Case. It simply cannot be argued that the current name is gigantea. Furthermore, the
only numerically significant observation is the predominance of Dipsochelys over
Aldabrachelys (83.2% vs. 16.8%).
The ‘Code’ must not be taken apart; it must be understood, accepted and followed
Should zoological nomenclature be regulated by a set of rules or by ‘polls’ open to
anyone, even without any experience in taxonomy? If so, then the easiest way
would simply be to get rid of the Code, and let so-called ‘consensus’ establish the
valid names of taxa. Experience in the past has amply shown that consensus rarely
ever leads to stability and clarity in the use of names, and often leads to chaos,
which is precisely why a Code had to be established in the late 19th century. We
believe that dismantling the Code in favor of common opinion would be a
mistake.
Finally, why should we reject the name Testudo dussumieri, which honours the
memory of Jean-Jacques Dussumier, the first traveller who brought back an Aldabra
tortoise with its precise locality and offered it to science? If one operates by the letter
of the law (Code), as we have, and not by passion or emotion, it is clear that the first
valid name for the Aldabra tortoise is Testudo dussumieri.
Additional references
Bour, R. 2008a. The type specimens of Testudo angulata Schweigger, 1812 and Testudo bellii
Gray, 1828. Emys, 15(1): 28–34.
Bour, R. 2008b August Friedrich Schweigger (1783–1821). Pp. 7–54, in Bauer, A.M. (Ed.), The
life and herpetological contributions of August Friedrich Schweigger (1783–1821). Society
for the Study of Amphibians and Reptiles, Villanova, Pennsylvania, U.S.A.
Bour, R. & Maran, J. 1998. Taxinomie de Mauremys leprosa (Schweigger, l8l2) dans le sud du
Maroc: la ‘‘Tortue aux yeux bleus’’ (Reptilia, Chelonii, Geoemydidae). Manouria, 1(2):
22–52.
Dubois, A. 1997. Proposals concerning the conditions needed for a name being eligible for
conservation. Bulletin du Muséum National d’ Histoire. Naturelle, (4)18(3–4): 317–320.
Dubois, A. 2007. Naming taxa from cladograms: some confusions, misleading statements, and
necessary clarification. Cladistics, 23: 390–402.
Frost, D.R., McDiarmid, R.W. & Mendelson, J.R. III 2009. Response to the point of view of
Gregory B. Pauly, David M. Hillis, and David C. Cannatella, by the Anuran subcommittee
of the SSAR/HL/ASIH scientific and standard English names list. Herpetologica,
65(2): 136–153.
Iverson, J.B. & McCord, W.P. 1989. The proper taxonomic allocations of Emys nigricans
Gray, Emys muticus Cantor, and Geoclemys kwantgtungensis Pope. Amphibia-Reptilia,
10(1): 23–33.
Pritchard, P.C.H. 1996. The Galápagos tortoises: nomenclatural and survival status. Chelonian
Research Monograph, 1: 1–85.
Rhodin, A.J.G. & Carr, J. 2009. A quarter millenium of uses and misuses of the turtle name
Testudo scabra: Identification of the type specimens of T. scabra Linnaeus 1758 (=
Rhinoclemmys punctularia) and T. scripta Thunberg in Schoepff 1792 (= Trachemys scripta
scripta). Zootaxa, 2226: 1–18.

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