Flavio Mattavelli - matta.a@tiscali.it - August 2017 release.


Marginella glabella Complex Atlas

(ex Quick reference guide, January 2015 revision).


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 kleptons.

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 "La variabilità fatta specie" (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 Marginella glabella = G & Marginella irrorata = I.

The second page introduces Marginella glabella mutabilis Mattavelli 2005, hybridation subspecies GXI.

The third page regard Marginella glabella antinea & problematica ("hybrid" forms between GXP).  

By writing "species" I mean a biological category which may be either a true species or a true klepton.

D = Marginella desjardini Marche-Marchad, 1957, Guinea, 59,6 mm length, true species.

Marginella goodalli Sowerby, 1825, Senegal, 35 mm + 28 mm lengths, true species.

Marginella goodalli is unmistakable, except for with some "stocky & dark" forms of M. sebastiani.

Forms of S = Marginella sebastiani Marche-Marchad & Rosso, 1979, true species.


"stocky & dark" varieties, 45 + 38 mm, well toothed margin.

"lellia" varieties, in honour to my wife Lella. 41 + 41 mm, vinated body, smooth margin. The specimen on the extreme right is juvenile, with thin margin.


"mixed & elongate", different varieties; it follows a particular specimen, Guinea, 52 mm. These forms are confusable with M. pseudosebastiani; to distinguish them, see "The discriminating factor", mainly in M. sebastiani note the absence of subsutural axial flames.

P = Marginella pseudosebastiani Mattavelli 2001, the biggest specimen of the sintypes, 64,4 mm length,

typical form pseudosebastiani. Also see: the links page.


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)


The livery of Marginella glabella is very variable, usually between 30 & 50 mm length. 

The distribution of M. glabella is generically West Africa (Marocco to Guinea?), indeed one should investigate on the place of origin and on the bathymetry of all varieties.


Right: M. glabella, almost "subtypical" (couloured) & almost "albino" mixed forms, different localities, Senegal & Mauritania, medium size. 


Trend of some varieties towards M. glabella mutabilis Mattavelli 2005 new subspecies, descripted in "La variabilità fatta specie", second page.


However the variety "mutabilis" could be instead a possible but improbable new klepton:

Marginella (kl.?) mutabilis, hybridogenetic hybrid between M. glabella X M. irrorata (pictured on the left, 33,7 mm length).

Since there is a clear biological separation between the species G & I, I think this klepton is improbable, but genetic evidences on the mollusks are necessary.

In the Canary Islands M. glabella is smaller, namely dwarf glabella

Left: M. glabella, 25 & 30 mm length, Lanzarote Island, depth - 20 m, sand soundings.


M. glabella albida, "albino", 35 mm, Mauritania (picture from eBay). In Mauritania there are entire populations of so-called "albinos", or better leucistic forms, if not different species.

They could be also hybridogenetic hybrids (kleptons) between M. glabella X M. irrorata, namely Marginella kl. mutabilis albida, but the exact biological category is to be investigated (* see Intermediate forms of G towards P).

I = Marginella irrorata Menke, 1828 true species

M. irrorata irrorata, 25 mm, "almost albino" ("common" M. irrorata is usually pink, see "La variabilità fatta specie", first page).

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.



The light spots may be well located in M. irrorata var. pseudoirrorata Mattavelli, 2017 (see pseudoirrorata.htm ).
Specimen 21,5 mm, West Sahara, strangerly amber-coloured.
Usually the background colour verges on amaranth.


M. glabella atlantidis Buey Suarez, 1980 = M. pseudosebastiani Mattavelli, 2001.

In my opinion, this "glabella gigas" is just M. pseudosebastiani. Buey Suarez identified a lot of varieties of the Complex, but he did not separate M. pseudosebastiani as a new species (article of Buey Suarez: 1980, La Conchiglia magazine, Roma, Italia, n°138/139 settembre/ottobre, Evolver publisher)


Intermediate forms of M. glabella towards M. pseudosebastiani. 

It is opportune to report the variety M. glabella antinea Mattavelli 2005: wide treatment in my web article: "La variabilità fatta specie", third page, regarding the "problematica" variety.

Another interesting variety of M. glabella is the "deep water form" of Lipe (1991, Marginellas, THE SHELL STORE, St. Petersburg Beach, Florida, USA, booklet with pictured specimen 44 mm length), pale form characterized by prolonged conoidal apex, instead of usually lowered puffed out apex of "standard" M. glabella. In my opinion this "deep water form" is M. glabella hybrid towards M. pseudosebastiani. This "deep water form" can be framed as a subvariety of M. glabella antinea too. But the "deep water form" is also inclined to M. glabella mutabilis. So the variability is very complex and the identification is morfologically difficult. 

In other cases the identifications of some shells, shared by the morphologic hybridation G X P, are much more uncertain.

In 2001 generically I have named "problematica" a stocky form, with lowered conoidal apex.

Left: Marginella glabella named "problematica" form (Mattavelli 2001, Malacologia Mostra Mondiale magazine, n°34, page 6), Mauritania, 36,7 mm length, in Mattavelli collection, strange "hybrid" towards M. pseudosebastiani. Subsutural flames are present, but they are disguised as " almost albino". Small white points are perceptible on the pale hazel background, on the back of the shell.

In fact this "problematica" is not a single variety, but an archipelago of similar little varieties. So generically, in my opinion, with after-wit, other "problematica" morphs could be subvarieties of M. glabella antinea 2005, in most cases (if antinea was a variety of the species M. glabella).

Right: Marginella..."antinea", 40,8 mm length, probable klepton.

Actually M. glabella antinea 2005 could be instead a true hybridogenic hybrid between G X P: Marginella (kl.?) antinea Mattavelli 2011, splittered in the subvarieties of this klepton: typical (morph as antinea Mattavelli 2005), problematica (Mattavelli 2005), "deep water form" (Lipe 1991) and their prospective leucistic forms (*).  

The stated subvarieties of supposed M. kl. antinea 2011 sometimes can seem in alternative subvarieties of supposed Marginella kl. mutabilis. Well the apparent same forms sometimes may be a morphologic bridge between "antinea" & "mutabilis". Supposing it is not a mistake of morphologic identification, could we presume a true superklepton "antinea" X "mutabilis" in the extended M. glabella Complex? No, because a morphologic bridge is not a true biologic bridge.  

I think M. glabella, pseudosebastiani & irrorata are 3 different species, with only 2 different hypothetical possible relative kleptons (kl."antinea" = glabella X pseudosebastiani & kl. "mutabilis" = glabella X irrorata). 

As to morphology and sizes the klepton "antinea" is very probable; on the contrary the klepton "mutabilis" is criticizable: it may be instead a variety of the species M. glabella.

I would exclude the third (logically hypothetical) klepton M. pseudosebastiani X irrorata, since I don't think a true hybridation is possible between P (too big) & I (too small), judging by sizes of the shells and by their too different morphology.

In the future the answer, since it is necessary to add the new "species" M. (kl.?) pseudoglabella to the Complex. Genetic evidences are necessary on the mollusks.


(*) The cases of "albinos", or better leucistic forms, complicate the situation, if they not are different species, or varieties of species, but if they are kleptons. In the species M. pseudosebastiani, desjardini, sebastiani, I think "albinos" are rare. However they may exhist. The "albinos" are mostly in the species M. glabella & irrorata and in their "hybrids", almost always in the supposed hybridogenetic hybrid Marginella kl. mutabilis albida. I have thought "albida" as a leucistic form of the supposed klepton "mutabilis". On the contrary the various "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. 


L = Marginella (kl.?) pseudoglabella Mattavelli, 2017 new "species"


The photo of the side specimen (n ° 926624) is owned by Conchology, Inc., a Web site where similar morphs are all referred as "lamarcki cf.", that is to compare with M. lamarcki, although the true species M. lamarcki Boyer, 2004 is much smaller and different, framable out of the M. glabella Complex, and therefore here neglected.
The specimen of the photo is from Senegal, 50.1 mm long, and belongs to the series of sintypes of the new "species" M. (kl.?) pseudoglabella, which I refer to 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 length.
The topic was first discussed in the
Universo lumperia article and then on the Links page.
For considerations that I hope will be conclusive see the article:
<< New look at the worlds of M. glabella & pseudoglabella >>

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.  

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.

Example of doubtful form, verso & recto 43 mm length, Nouadhibou, Mauritania, 1,87 total stretch, juvenile specimen, because of the thin lip.


In my first opinion the form was a specimen of M. pseudosebastiani, but subsequently I thought it was a klepton, maybe PXG.

An identification with 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, LXP o LXS.

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 (see the stretches table) and with different pattern, with clear spots in the clear bands around the shell.

typical form "pseudodesjardini", pictures from the "Synthese" of Roger Le Béon 2008. 

The typical form appears as a "hybrid" S X D (legenda in the stretches table); denomination ex and alias synonymous of the form "incredibilis" Mattavelli 2011.


form giselica Mattavelli 2013, Senegal, 73,5 mm length (Gisela's pictures).

It could be or a variety of M. pseudosebastiani, but more probably it is a variety of M. pseudodesjardini, or less probably a true hybrid or a possible klepton P X D or P X R. The adult form "giselica" has the margin towards the shell mouth smooth, while "typical pseudodesjardini" has the same margin finely serrulated.


Shell total stretch = Shell length / Longest diameter (including the shell margin jut width).

Summary of the approximate

shell total stretches  




Small specimens stretches





mean stretches

Big specimens stretches








M. irrorata = I









M. glabella = G









M. sebastiani = S









M. pseudoglabella = L









M. pseudosebastiani = P









M. pseudodesjardini = R









M. desjardini = D









Distribution & dappling of the spots



























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, including in this complex also the species M. pseudosebastiani for shell affinities, but excluding all other species which are also very close to the G, S, P.


This reductive idea of ​​the strict complex was born to qualify the biological situation, but 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": M pseudodesjardini = R and M. pseudoglabella = L.


All the above-mentioned 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 (a topic that is however unmanageable elementary), 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.

Flavio Mattavelli

In this page all specimens and pictures come from Mattavelli's collection, except specimens and 2 pictures of the typical form pseudodesjardini Le Béon, from Le Béon Web site, the 2 pictures of the giselica form from Gisela Shells Shop, the image of M. pseudoglabella from Conchology Inc.. Non-profit reproduction authorized only citing the sources and names of the respective Authors.


Home (in 2020 there are 41 pages in total)


Alcune pagine della Sez. Conchiglie (16 pag.)

Some pages of the Shell Section (16 pag.)

Marginella pseudosebastiani Mattavelli, 2001 nuova specie. Precisazioni sul complesso di M. sebastiani e glabella (archivio 2004, solo lingua inglese)

Marginella pseudosebastiani Mattavelli, 2001 new species. Statements on the M. sebastiani & glabella Complex (2004 archives, English only)

Marginella klepton pseudodesjardini? Altri klepton nel Marginella glabella Complex? Con tabella fotografica degli ibridi e delle specie base. Revisione 2014.

M. klepton pseudodesjardini? Other kleptons in the Marginella glabella Complex? With photografic table of the different hybrids & basic species. 2014 revision (Italian only).

Universo lumperia.Morfi ibridi SXP e SXG = possibile nuovo Marginella kl.? pseudoglabella Mattavelli, 2014.

Universo lumperia. Morphologic hybrids SXP and SXG. Possibility of the new M. kl.? pseudoglabella Mattavelli, 2014 (Italian only)

Concetti di Specie/klepton, relaise 2014

Specie/klepton Concepts, 2014 relaise (Italian only)

Marginella pseudodesjardini Le Béon, 2012 vera nuova specie (ex et alias "kl.? incredibilis" Mattavelli, 2011), ma che potrebbe essere invece un notevole ipotetico klepton. Note anche sulla diversa forma "pseudodesjardini giselica" Mattavelli, 2013.

Marginella pseudodesjardini Le Béon, 2012 new species, today studied as a true species,but which could be a remarkable klepton instead, ex et alias "kl.? incredibilis"  Mattavelli, 2011. Notes on the different "pseudodesjardini giselica" Mattavelli, 2013 form. (Italian only)

(pagina doppia italiano e inglese, aggiornamento 2017)

(English/Italian double page, 2017 update)

Marginella irrorata pseudoirrorata Mattavelli, 2017

pseudoirrorata” 2017, variety of Marginella irrorata (Italian only)

Nuovo sguardo ai mondi di M. glabella e M. (kl.?) pseudoglabella Mattavelli, 2017

"pseudoglabella supposed new species", 2017 (Italian only)

Descrizione comparativa di Marginella (Kl.?) pseudoglabella Mattavelli, 2018 nuova "specie"

"pseudoglabella settled new species", 2018 (Italian only)

ex Guida in italiano di identificazione fotografica delle specie attuali del Marginella glabella Complex e di alcuni loro ibridi morfologici, con disegno riassuntivo delle taglie e puntinature delle conchiglie. Aggiornamento 2017.

ex Quick reference guide (present page, English only). Pictures of Marginella sebastiani, desjardini, pseudosebastiani, pseudodesjardini, goodalli, glabella, irrorata, pseudoglabella & some morphologic hybrids. Update 2017.

Individuazione dell'ipotetica Marginella (Kl.?) visayae Mattavelli, 2018, che viene ipotizzata come nuova "specie", insieme con M. lellae & M. pseudoirrorata, tuttavia ritenute rispettivamente “varietà” M. pseudoglabella lellae & M. irrorata pseudoirrorata.

 Marginella (Kl.?) visayae Mattavelli, 2018, supposed new “species” or klepton G X I (Italian only)

Articolo “La variabilità fatta specie” (3 pag.) da revisionare

La variabilità fatta specie” article (3 pages only in Italian) to be revised


Other Sections pages, accessible from the home pages of the single other 3 Sections:


Model Aircraft Section (16 pages only in Italian: “aeromodellismo”, canard & flying wings in paper & cardboard models).

Machinery Section (7 pages, some in English) with references to the machines built by the Cavalleri Mattavelli Sas company.

Gorgonzola Section (2 pages, only in Italian). Long monograph on "My Gorgonzola after 1990", miscellany with origins of the city and the homonymous cheese, supplemented by some chatter from a conchologist.