Marginella glabella & sebastiani Complex Atlas
(ex Quick reference guide).
I have developed my ideas regarding the Marginella glabella Complex. Today I believe it is possible that there are some hybridogenic categories in it, that is some
Yet I have left unchanged, as archives, some pages regarding the varieties previously thought only as varieties of species, without reference to kleptons.
See many pictures in the wide & exaustive article " " (3 archives pages only in Italian), regarding the variability of Marginella glabella, M. irrorata, M. pseudosebastiani, without klepton concept.
The starting page is about the basic distinction between .
The second page introduces hybridation subspecies GXI. Mattavelli 2005,
The third page regards .
By writing "species" I mean a biological category which may be either a true species or a true klepton.
O = Marginella goodalli Sowerby, 1825, Senegal, specimens 35 mm and 28 mm length, true species.
Marginella goodalli is unmistakable, except for with some "stocky & dark" forms of M. sebastiani.
S = Marginella sebastiani Marche-Marchad & Rosso, 1979, true species. Different varieties:
S = mixed & elongate, nearly typical “sebastiani", further divisible in different sub varieties, not pictured.
It's shown a particular specimen, Guinea, 52 mm.
These forms are confusable with M. pseudosebastiani; to distinguish them, see , mainly in M. sebastiani note the absence of subsutural axial flames.
F = "sebastiani lellia" varieties, in honour to my wife Lella.
There are 2 basic sub varieties of “lellia”, represented specimens 40 and 40 mm length, vinated body, toothed adult specimens, with large light spots on the livery:
left “lellia tondapex”,
right “lellia acutapex”.
There are also “stocky & dark” varieties, like as the 2 next “sebastiani lellia acutapex”, 45 and 38 mm:
P = Marginella pseudosebastiani Mattavelli 2001, ,4 mm length, typical form. Also see: . , 64
Clarification concerning M. glabella atlantidis Buey Suarez, 1980.
This marginella was then named M. pseudosebastiani Mattavelli, 2001 new species.
Buey Suarez (in an article of the magazine La Conchiglia, Rome, n ° 138/139 September / October 1980, Evolver edizioni) identified a form "glabella gigas" calling it "glabella atlantidis", without separating it as a new species. Instead it is a very different species from M. glabella.
Direct comparison between Marginella sebastiani & Marginella pseudosebastiani.
On the left Marginella pseudosebastiani Mattavelli 2001, 58,4 mm, sintype.
On the right Marginella sebastiani Marche-Marchad & Rosso 1979, 59,6 mm, "elongate" form.
G = Marginella glabella (Voluta glabella Linneus, 1758-1767; Genus Lamarck, 1799). True species, type of the Genus Marginella.
There are many and very variable subspecific forms of Marginella glabella that can be confused with M. irrorata. For the basic identification of these 2 species, I refer to my article " " (only Italian language, 2005-2006), where, however, I did not suppose the possible existence of klepton, nor of M. pseudoglabella or of M. visayae yet.
In 2021 I analyzed different morphological forms of glabella-like etc., looking . The livery of G is very variable, with shells usually between 30 and 50 mm length. The distribution is generally West Africa, from Morocco to Senegal, however it would be better to investigate the places of origin and the bathymetry of all the individual numerous varieties.
The 6 specimens depicted are almost typical of M. glabella, 2 more colored, 2 almost "albino" and 2 intermediate forms with degrading liveries towards a light background. Personally I consider the intermediate liveries to be typical, as the more colored ones may, on the other hand, encroach on the burgundy typologies of the morphs of some M. pseudoglabella, which however are also more elongated and, in adults, larger in size (see and definition of “”).
I remember the presence of some forms that before were all G mutabilis and G antinea, but now they should instead converge in part mostly in M. visayae and in a minimal residual part remain forms of G. Some morphs of M. glabella show notable tendencies of morphological hybridization towards M. irrorata, to be assumed the existence of a form . The "mutabilis" variety could perhaps even be a form of a between M. glabella X M. irrorata. However, since there is a clear biological separation between these 2 species, I think this klepton is unlikely, while the identification of almost all "mutabilis" with "visayae" is highly probable. Genetic analyzes of molluscs are needed to settle the issue.
In the Canary Islands M. glabella is smaller, namely dwarf glabella, like as this other 6 specimens , from 25 to 30 mm length, Lanzarote Island, depth - 20 m, sand soundings. The small “glabella” of the Canary Is. can also be well confused with M. irrorata and M. velai, especially if in “albino” forms.
The cases of "albinos" complicate the Complex specific situation.
On the left M. glabella albida, "albino", 35 mm, Mauritania, where “albida” constitute entire populations of so-called "albinos", or better leucistic forms, If they not are different species, or varieties of species, they could be kleptons.
In other species of the Complex I think "albinos" are rare, however they may exhist. The "albinos" are mostly in the species M. glabella & irrorata and in their "hybrids". The exact biological category is to be investigated.
The various similar "albida" forms really could be in alternative or a form of the species M. irrorata or of the species M. glabella, or they could be at a time a new species too, to be defined genetically.
In the article irrorata albinea”, unclassifiable “tizianica” and M. mattavellii Cossignani, 2021 new species. I considered the forms “
I = Marginella irrorata Menke, 1828, true species.
I = Marginella irrorata irrorata, 25 mm, "almost albino". Usually M. irrorata is pink, see "
By morphology it is very difficult to distinguish M. irrorata from M. glabella. Generally M. irrorata is under 30 mm length. The mollusk is different but the shell is similar. I think that most "irrorata gigas" on sale with exceptional size (40 mm) are simply varieties of M. glabella, or more likely varieties of M. visayae.
T = Marginella
irrorata pseudoirrorata Mattavelli, 2017.
Specimen 21,5 mm, West Sahara, strangerly amber-coloured.
Usually the background colour verges on amaranth.
The light spots may be well located in M. irrorata variety
Some consider “pseudoirrorata” a separate species, above all due to the presence of decidedly “
V = Marginella (kl.?) visayae Mattavelli, 2021. In October 2021 I introduced M. visayae in , n ° 113, p. 36/41, as a possible "sibling species" of G & I. Some "G mutabilis" and "G antinea", varieties so called by me in 2005, then understood as of M. glabella towards M. irrorata and M. pseudosebastiani, are now considered M. visayae.
Holotype of V, 41 mm length, deposited at the Malacology Museum of the World Exhibition, Cupra Marittima.
The holotype is characterized by an ultra-fine clear speckling, which is best distinguishable with a magnifying glass.
Today I identify the majority of the "antinea" and "mutabilis" morphs as varieties of the "visayae" species, see article , 2021, as well as ".
There are also specimens with coarser dots, called M. visayae pseudovisayae. The one shown, 41.4 mm long, is part of a syntypical series presented in ", where in 2018 the specimen was declared "ex antinea".
Some other morphs of "antinea" or "mutabilis" could still be identified as klepton, not well specified morphologically (GXP? Or GXI?), perhaps also converging towards M. (kl.?) pseudoglabella = L and/or towards M sebastiani = S, in addition to the hypothetical supposed hybridizations GXP and GXI.
W = Marginella velai Ahuir Galindo & Tiziano Cossignani, 2020.
In July 2020, a new species, of which this specimen is almost typical, was introduced in issue 108 of the (Malacology World Exhibition of Cupra Marittima). Average length of the various paratypes about 30 mm, place of origin Morocco. The species can be confused with some already known species of the Marginella glabella Complex, intended to include Marginella irrorata Menke, 1828 and even Marginella lamarcki Boyer, 2004.
L = Marginella (kl.?) pseudoglabella Mattavelli, 2018 new species.
The photo of the side specimen (n °
926624) is owned by Conchology Inc., a Web site where similar morphs were all
referred as "lamarcki cf.", that is
to compare with M. lamarcki, although the true
species is much smaller
and different, framable out of the M. glabella
Complex, and therefore here neglected.
The specimen of the photo is from Senegal. It is 50.1 mm long and belongs to the series of sintypes of the new "species" M. (kl.?) pseudoglabella. I refer to it as a new biological category of clear morphology, different from the previous species, but of dubious biological nature, probable klepton of hybrid morphology GXS, with a tendency to PXS; anyway with a different morphology both from G, S, P and I.
The other approximately 30 sintypes of Conchology Inc. range from 46 to 68.8 mm shell
The topic was first discussed in the article and then on the
For considerations that I hope will be conclusive, see the article , finally
E = Marginella (kl.?) pseudoglabella lellae Mattavelli, 2018, perhaps a new "species", not common.
The specimen on the side is 52.5 mm long.
It is characterized by a regular dotting of the livery, analyzed in the article
Be careful not to confuse the name with the forms M. sebastiani lellia = F, analyzed in the article
Morphologic "hybrids" of GXP or GXS or PXS, or GXL or PXL or SXL. Note that the term "hybrid" frequently is used only with a morphological purpose, but the introduction of the klepton concept (hybridogenetic hybrid) upsets any identification based only on the biological species concept, or species varieties (and their sterile hybrids) concepts.
There may also be hybrids of M. visayae & irrorata, etc., but they are not considered here for simplicity.
The Complex of the "species" G, P, S, L is morphologically hybridable with difficult identification of some forms of the single species or their "hybrids". The apparent hybrids are mostly referable to a single one of the species, but in some cases that is almost impossible.
On the left example of doubtful form, verso & recto 43 mm length, Nouadhibou, Mauritania, 1,87 total stretch, juvenile specimen, because of the thin lip. If it is not probably a specimen of M. pseudosebastiani, I think it is a , maybe PXG, or PXS, or PXL.
An identification with only typical L is not acceptable, because the mouth of the shell is too lengthened.
However an identification is possible with an atypical variety of M. (kl.?) pseudoglabella, or with one of its "hybrids", among LXG, or LXS.
In other cases there are also few morphological hybrids that can be estimated M. glabella X M. sebastiani and it may seem easy to attribute them only to one or the other species. In reality, this is not easy at all.
R= Marginella pseudodesjardini Le Béon, 2012. It is longer and more coloured than typical M. pseudosebastiani.
M. pseudodesjardini is coloured as M. sebastiani and on the contrary it presents the subsutural axial flames.
Besides M. pseudodesjardini is generally less elongate than M. desjardini and with different pattern, with clear spots in the clear bands around the shell.
typical form "pseudodesjardini", pictures from
The typical form appears as a "hybrid" S X D; denomination ex and alias synonymous of the form
form “giselica” Mattavelli 2013, Senegal, 73,5 mm length (Gisela's pictures).
It could be or apseudodesjardini, or less probably a true hybrid or a possible The adult form "giselica" has the margin towards the shell mouth smooth, while "typical pseudodesjardini" has the same margin finely serrulated. but more probably it is a variety of M.
D = Marginella desjardini Marche-Marchad, 1957, Guinea, 59,6 mm length, true species.
Table of approximate average total shell lengths and shell elongations (= stretches).
Observe that the average lengths are not arithmetic, but the average is shifted towards the maximum lengths for the specimens of the small species and towards the minimum ones for the specimens of the large species. Tot. elongation = Tot. length / Maximum diameter including the expansion of the shell margin.
Extended Complex graph.
Being able to easily separate the species M. goodalli and M. desjardini and considering M. irrorata biologically well different from M. glabella (but non morphologically), in 2001 I proposed a Marginella glabella & sebastiani Complex in the strict sense, by including in this Complex also the species M. pseudosebastiani for shell affinities, but excluding all other species which are also very close to G, S, P.
Undoubtedly we must also take into account the neighboring species, better meaning a Marginella glabella & sebastiani Complex extended to all known species morphologically similar to G, S, P, including the latest "discoveries", but
Besides in the next graph I neglected the small sp. M. aurantia, lamarcki, mattavellii, velai, etc. mentioned in the
Some species and some of their varieties have been set in the drawing by comparing the size of the shell and the distribution of the livery dotting. The most evasive species as to morphological identification is in the bottom left (M. irrorata), while, increasing the coordinates, the identification of the varieties appears facilitated by the size and livery of the shells.
Note: the size of the dots and the size of the shells are chosen as Cartesian coordinates, but some other morphological characteristics could be chosen. For example we could choose on the abscissa the total stretch = maximum length / last round diameter, or the mouth stretch = shell length / maximum mouth width, and on the ordinate the subsutural flammulation, or the profiling of the shell or of the single loop.
They are evanescent topics, but partially quantifiable with one of the previous stretches, adding other treacherous concepts, such as the curvature of the loop and the last turn, and mathematicising the curvatures with the introduction of the measures of the various angular determinants, identifiable in the profile of the shells, which is practically impossible.
By changing the reference coordinates, the mutual positions of the species and their varieties in the design could change, however they would always remain in conditions of relative proximity between the species and their most similar varieties.
Update 25/09/22. Non-profit reproduction authorized only citing the sources and names of the respective Authors of the images. If necessary, I recommend printing with minimum margins (9 sheets A4).
The site is divided into 4 Sections (a total of 51 pages in 2022. The individual sectional pages are accessible by linking the Homes of the individual Sections., , , ), for
All pages are also accessible from the
Green in English, a list of 24 sectional pages (including this one), regarding Shells Section only.