Comment on Psonis et al. (2015): ‘ Evaluation of the taxonomy of Helix cincta (Muller, 1774) and Helix nucula (Mousson, 1854); insights using mitochondrial DNA sequence data’
Author
Neubert, Eike
Department of Invertebrates, Naturhistorisches Museum der Burgergemeinde Bern, Bern, Switzerland;
Author
Korábek, Ondřej
Department of Ecology, Charles University in Prague, Prague 2, Czech Republic
text
Journal of Natural History
2015
2015-03-31
49
37
2257
2263
journal article
21129
10.1080/00222933.2015.1021874
4b5110af-4195-46cb-bc6a-30668c21c25c
1464-5262
4000019
Helix nucula
Mousson, 1854
(
Figure 1A
)
Helix figulina
var.
nucula
Mousson, 1854
, Mittheilungen der naturforschenden Gesellschaft in
Zürich
, 3 (8): 367, 372–373 [
Smyrna
(Bellardi); =
Izmir
] [non
Helix nucula
sensu L.
Pfeiffer, 1859
].
Type specimens:
syntypes
ZMZ 506381, ZMZ 506394.
This name was introduced by Mousson for a white-lipped species from
Turkey
. The species is also known from a number of Aegean Islands, particularly from the Dodekanissos, and is widespread along the southern coast of
Turkey
, where it is usually recorded under the name of
H. figulina
. This taxon was originally described in the genus
Helix
and thus the taxon authority should be cited without brackets.
In 1859, Louis Pfeiffer used the same name,
H. nucula
, for a
Helix
species from
Egypt
that he had received under this name from Ludwig Parreyss, an Austrian shell dealer, as shown by the wording ‘Parreyss in sched.’ in his text. Pfeiffer was aware of Mousson’ s
nucula
from 1854 as he listed it in his synonymy, but regarded Parreyss (the ‘name supplier’) as the author of the name. As in many cases, Pfeiffer ‘re-described’ the species, which until today has been mistaken by subsequent researchers as the valid description for
Helix nucula
, and thus contributed to the present chaos. Unfortunately, the specimens from
Egypt
were dark-lipped, as can be seen from Pfeiffer’ s text: ‘perist. fuscum, marginibus callo nigro-castaneo intrante junctis’, and thus represent a species different from
H. nucula
Mousson, 1854
. So far, no original specimens of
H. nucula
sensu
Pfeiffer, 1859
could be traced in the major European museums which are known to hold Pfeiffer specimens.
It should be stressed that
Helix nucula
sensu
Pfeiffer, 1859
has been widely used since its ‘re-description’ (e.g.
Kobelt 1904
;
Kaltenbach 1950
;
Zilch 1952
) without recognising the nomenclatural situation.
Which species were analysed?
In the tree of
Psonis et al. (2015)
, the name ‘
H. cincta
’ appears in three genetically distinct clusters, a fact that shows the authors follow another concept of this also black-lipped species. Thus, a clarification of the question – Which species has been investigated? – is urgently needed. Without having seen the specimens investigated, we only can use our own knowledge on the whole genus, which among others is based on the investigation of almost all
type
specimens available for names published in the group (
Neubert 2014
).
We here follow the sequence of the black-lipped group from left to right (
Psonis et al. 2015
, fig. 2). The first problem arises by application of the name
H
. cf.
cincta
for the black-lipped species from
Tunisia
. No
Helix
specimens from Northern Africa have ever been placed in
H. cincta
. In their revision of the Tunisian continental malacofauna,
Letourneux and Bourguignat (1887)
did not mention
Helix cincta
O.F.
Müller, 1774
; however, they list
H. melanostoma
(together with
H. nucula
and other taxa) as very abundant from the area.
Helix melanostoma
is a well-known species, and has been depicted in several identification guides (
Kerney et al. 1983
;
Fechter and Falkner 1990
;
Welter-Schultes 2012
;
Neubert 2014
). It differs from
H. cincta
markedly, by both shell shape and colour. Our own unpublished data show the sequences of
Psonis et al. (2015)
to nest among the
H. melanostoma
populations from
Tunisia
, thus fully confirming our expectations (
Korabek et al. 2015
). We here figure the
syntype
specimen of a synonym name of
Helix melanostoma
Draparnaud, 1801
from
Tunisia
(
Figure 1B
).
The next problem is the presence of two widely separate ‘
cincta
’ clades in the tree.
Psonis et al. (2015)
have suggested
H. cincta anatolica
Kobelt, 1891
(in green) to be ‘raised to species level’. This claim is flawed because of a misunderstanding of the taxonomy of
H. cincta
. Within this species, three subspecies used to be recognised (
Knipper 1939
; Zilch 1960) found in (1) northern Adriatic coastlands (
H. cincta cincta
Müller, 1774
); (2) in
Greece
and the
Aegean
(
H. cincta ambigua
=
H. cincta borealis
Mousson 1859
); (3) in
Turkey
(
H. cincta anatolica
,
Figure 1C
). Out of these, Psonis et al. have sampled the last two, while the nominotypical subspecies is not included in their dataset. Therefore, their data cannot provide any support for the separation of
H. cincta anatolica
from
H. cincta cincta
. Based on anatomical, shell morphological and genetic investigations of Italian as well as Turkish specimens, we consider
Helix
(
Pomatia
)
cincta
var.
anatolica
Kobelt, 1891
a
junior synonym of
Helix cincta
Müller, 1774
(
Neubert 2014
;
Korabek et al. 2015
).
However, another aspect is much more interesting: the so-called ‘
Helix cincta
’ clade (
Psonis et al. 2015
, fig. 2, in red) comprises specimens originating from
central Greece
and western
Crete
, including a sample from Kerkyra Island, which is the
type
locality of
Helix ambigua
var.
borealis
Mousson, 1859
. These results clearly indicate that
H. cincta borealis
is a separate species. Actually,
H. borealis
has already been considered separate from
H. cincta
by E. Neubert, and his view has been followed by some projects (Fauna Europaea; International Union for Conservation of Nature [
IUCN
] Red List).
The central part of the Bayesian tree of
Psonis et al. (2015)
contains a cluster called ‘
Helix nucula
’ (in orange). It comprises specimens originating from localities in Crete, the island Anafi, the Cyclades and
Libya
. This result confirms that there is another black-lipped species living in the East Mediterranenan basin besides
H. cinta
and
H. borealis
, corresponding to ‘
H. nucula’
as understood by
Kaltenbach (1950)
, and comprising also populations from the southern Aegean. Accepting the existence of such an East Mediterranenan species, the next nomenclaturally available name has to be used for this taxon. This name would then be ‘
Helix pronuba
’ published in the original combination
Helix thiesseana
var.
pronuba
Westerlund & Blanc, 1879
, which originates from ‘Crete, Messarà’.
Figure 1. (A)
Helix nucula
Mousson, 1854
, syntype ZMZ 506381a, shell diameter 28.8 mm. (B)
Helix melanostoma
Draparnaud, 1801
, syntype of
Helix uthicensis
Pechaud, 1883
, ruins of Uthica, Tunisia, MHNG 18185, shell diameter 36.2 mm. (C),
Helix cincta
Müller, 1774
, syntype of
Helix
(
Pomatia
)
cincta
var.
anatolica
Kobelt, 1891
, ‘Hieronda’ (southwest Turkey), SMF 9949, shell diameter 34.9 mm. (D)
Helix pronuba
Westerlund & Blanc, 1879
, syntype of
Helix thiesseana
var.
pronuba
Westerlund & Blanc, 1879
, GNM 1723, shell diameter 26.3 mm. (E)
Helix borealis
Mousson, 1859
, possible syntype ZMZ 506307, Grecce, Argostoli, shell diameter 34.65 mm.
Conclusions
Molecular phylogenetics is an irreplaceable tool for taxonomists, but interpretation of the results must be based on clear taxonomic concepts corroborated by all available resources – that is, the primary reference, the subsequent taxonomic literature and the
type
specimens of the organisms of interest. Otherwise, molecular phylogenetics can cause confusion with detrimental consequences to follow-up studies (e.g. ecological and evolutionary). Probably, the authors followed the mainstream literature in the apparently wrong application of the names discussed above. In the course of his taxonomic revision of the genus
Helix
, the first author noticed the problem of the ‘
nucula
misidentification’ already years ago, and consequently recognised
Helix nucula
Mousson, 1854
as a valid species (
Neubert 2014
). This information was disseminated to the community and shared with many colleagues. Thus, findings of
H. nucula
Mousson, 1854
have been reported from southwestern
Turkey
in two papers cited by
Psonis et al. (2015)
,
Neubert et al. (2000)
and
Örstan et al. (2005)
, both referring to the white-lipped species. Later, these results were used for the preparation of the European Red List of Non-marine Molluscs (
Cuttelod et al. 2011
). These results were criticised by Psonis et al.; however, this opinion reflects their misinterpretation of the taxonomic and nomenclatural problem as explained above. They have probably followed AnimalBase and Welter- Schultes (2012), where these two taxa are confused and their distribution data pooled together.
Psonis et al. (2015)
also used sequences of
H. pomatia
and
H. lucorum
, both downloaded from GenBank and both from unknown localities, and we urge against this practice, where a voucher specimen is not available.
The results of our analysis are: (1) the name
Helix nucula
Mousson, 1854
has to be applied to a white-lipped species; (2)
Helix nucula
sensu L.
Pfeiffer, 1859
is a description without any nomenclatural meaning; (3) the species
Psonis et al. (2015)
referred to as ‘
H
. cf.
cincta
’ from
Tunisia
is in fact
H. melanostoma
Draparnaud, 1801
; (4) the species
Psonis et al. (2015)
referred to as ‘
Helix cincta
’ from western
Greece
is
Helix borealis
Mousson, 1859
; (5) the species
Psonis et al. (2015)
referred to as ‘
Helix cincta anatolica
’ is in fact
Helix cincta
Müller, 1774
; (6) the species ‘
Helix nucula
L.
Pfeiffer, 1859
’ sensu auctores is a species in its own right, and has to be called
Helix pronuba
Westerlund & Blanc, 1879
, because these authors published the first valid description.
In order to recognise the species involved, each taxon is here briefly diagnosed to prevent further misidentifications (copied from
Neubert (2014)
; see also
Figure 1A–D
):
Helix (Pelasga) nucula
Mousson, 1854
(
Figure 1A
): shell small to moderately sized, thin, spherical, protoconch small, teleoconch with coarse axial riblets and surface granulation, aperture always white; flagellum as long as epiphallus + penis, long diverticulum surmounting bursa copulatrix in length.
Helix
(
Helix
)
pronuba
Westerlund & Blanc, 1879
(
Figure 1D
): shell small to very small, spherical, white or with up to five spirals, teleoconch with fine and densely spaced riblets and a prominent granulation, aperture deep chocolate brown. Morphology of genital organs unknown.
Helix
(
Helix
)
melanostoma
Draparnaud, 1801
(
Figure 1B
): shell of medium size, greyish to brilliant white, spherical, teleoconch sculptured by coarse ribs, labial callus and palatal area deep brown to chocolate-coloured; penis and epiphallus of same length, flagellum moderately long, glandulae mucosae much shorter than dart sac, pedunculus with a thick and short diverticulum.
Helix
(
Helix
)
cincta
O.F.
Müller, 1774
(
Figure 1C
): shell of medium size, thick, protoconch small, spiral bands no. 1 to 3 usually fused, columellar side of aperture relatively straight, aperture reddish-brown coloured; flagellum extremely long, pedunculus stem long, usually without diverticulum.
Helix
(
Helix
)
borealis
Mousson, 1859
(
Figure 1E
): shell of medium size, thin, protoconch small, aperture very large, dark brown, palatal area with expanded dark brown colouration. Morphology of genital organs unknown.
The differences in shell morphology are sufficient to recognise the species:
H. nucula
has a white lip, and thus differs from all other species listed here. The shell of
H. pronuba
differs from the other dark-lipped species by the presence of heavy granulation of at least the body whorl. The differences between
H. cincta
and
H. borealis
are more peculiar: the first species has a heavy, rather small and globular shell with a rounded aperture and often-fused spiral colour bands, while in the latter species, the shell is thinner, larger, the aperture is more oblique, and the colour spiral bands are often reduced in intensity or even lacking.
Disclosure statement
No potential conflict of interest was reported by the author(s).