by E.L. Heiman*)

Abstract: Intraspecific variation in Erosaria lamarckii is studied statistically using 211 shells (batches of shells from different localities), in order to learn whether it is a monotypic species or it may be divided into two subspecies. This study confirmed that in the majority of shells from East Africa the dorsal spots are partially ocellated with purplish grey, whereas in shells of the species from India and Thailand all dorsal spots are pure white, except for a few lateral ones. An intermediate zone separating Erosaria lamarckii lamarckii of East Africa from Erosaria lamarckii redimita of India, Thailand and Indonesia probably stretches from northern Kenya to Pakistan. Nine formae of E. lamarckii are recognized and illustrated.

Key words: Mollusca, Gastropoda, Cypraeidae, Erosaria lamarckii lamarckii, Erosaria lamarckii redimita, variability, intraspecific variation.

Erosaria lamarckii (Gray, 1825) lives in the Indian Ocean. In the west it is known from South East Africa and Madagascar to Mombasa, Kenya. In the east it is found in Thailand and Indonesia (Fig. 1). Coulombel (1993) did not mention it from Djibouti; Wells & Bryce (1988), Wilson & Gillett (1982) and Wilson (1993) did not mention it from W. Australia.

Yates (1972) reported finding of two shells supposed to be E. lamarckii in the stomach of a Sea Carp caught off Lancelin Is., Central West Coast of Western Australia. Perhaps this is the reason why Lorenz & Hubert (1993, 2000) included W. Australia in the range of distribution of E. lamarckii although Burgess, as mentioned by Yates, stated that the above two shells are in fact Erosaria cernica.

It is apparently uncommon around Mauritius: Michel (1988) does not mention it although Drivas & Jay (1988) do.

In this article an attempt is made to summarize the current knowledge about intraspecific conchological variation in the species.

Definitions accepted in this study

Species are groups of populations the shells of which can be separated from shells of all other species in the family by at least one well-recognizable diagnostic shell character showing no intermediate forms.

Subspecies are geographically separated populations of a species, of which the majority of shells differs by at least one shell characteristic from other groups of populations of the same species.

Formae are regularly found unusual shells differing from the other shells of a population in shape, color or pattern. Unlike subspecies, several different formae of a single species can be found together at the same locality and may comprise a considerable part of that population.

The main criterion for diagnosing cowry subspecies: geographical separation of groups of populations of a given species from other populations of the same species, and the existence or absence of at least one well-recognizable shell characteristic distinguishing the majority of shells (70% or more) of the group of populations from all other populations of the same species.

Subspecies of E. lamarckii

In the Prodrome Schilder & Schilder (1938) separated two subspecies cited below; they maintained this approach in their last work Schilder & Schilder (1971).

“In the East African lamarckii ( the dorsal spots are partially ocellated with purplish grey, whereas in the Indian redimita ( all dorsal spots are purely white, a few lateral ones excepted, which may enclose some chestnut marginal spots; besides, in the much larger lamarckii the dorsum is greyish fulvous instead of ochraceous to olivaceous, the aperture is less curved behind, the fossula is crossed by 3-5 (instead of 1-3) ribs, the fossular denticles are more accentuated, and the terminal ridge is less broad and never slit longitudinally.”

Melvill (1888:45, 68) mentioned Mozambique as a locality of E. lamarckii and E. Indies as a locality of f. redimita.

Schilder (1966:214) mentioned that the holotype of f. redimita is unknown and confirmed its original type locality Phuket (East Indies). A name “redimita” is established and used in taxonomic practice as a subspecific name since 1938. It listed in monographs on cowries by Steadman & Cotton (1946), Allan (1956) and Schilder & Schilder (1971). Burgess (1970, 1985) did not recognize subspecies in principle.

Lorenz (1992) and Lorenz & Hubert (1993, 2000) treated E. lamarckii redimita (Melvill, 1888) as a forma. In their opinion the subtle distinguishing features of redimita as a subspecies are not related to the original description given by Melvill (1888). It seems that in this case these authors did not pay attention to the fact that many names, which the Schilders designated for new subspecies in the Prodrome, refer only to the subject on hand and do not relate to any historical application by the person who originally coined that name. The Schilders merely wanted to revive vacant names (names that originally were applicable but due to lack of usage or other infringements of ICZN rules were no longer applicable to any existing population) instead of creating new names. This well meaning but poorly thought out tactic has complicated what on several occasions should have been straight-forward diagnostic exercises.

The relevant examples are given and discussed in Heiman (2002, 2004). The procedure used by the Schilders for choosing names has left some cowry students with the erroneous supposition that the type specimens and original descriptions, which were relevant to those old taxa, also represent conchological characters of the new cowry populations that now carried these old names. In this case the original type material and a description by Melvill do not represent the subspecies lamarckii redimita designated in the Prodrome; they are simply not relevant because the Schilders used the name as if had no history behind it.


The Schilders studied 509 shells of the species. The main diagnostic shell characters of lamarckii subspecies—the diffe-rence in size, the dorsal spots and fossula—sound convincing. Schilder & Benton (1962) confirmed by means of a statistical study the difference in shell characteristics of the two subspecies and indicated the population thriving near Mombasa, Kenya, as “intermediate between the widely distributed Indian and African races” Perhaps intermediate populations occupy a larger area. Bosch et al. (1995) pictured a typical specimen of E. lamarckii lamarckii from East Arabia. Apte (1998) mentioned E. lamarckii only from Karachi, Pakistan, Okha, Malvan south of Bombay and the Strait of Malacca. Typical shells of E. lamarckii redimita are mostly found around the Indian Peninsula. Probably it is better to talk about intermediate zones from Mombasa to Pakistan and from eastern Madagascar and Mauritius to W. India.

1. An approximate distribution of E. lamarckii


Additional statistical study

In shells of E. lamarckii lamarckii the dorsal spots are partially ocellated with purplish grey whereas in E. lamarckii redimita ocellations are found sporadically and mainly on the shell sides. This statement is checked statistically below in order to learn whether these subspecies can be separated conchologically using this shell character. The results can be seen in Table 1.

Table 1

Shell characteristics and formae of different populations of E. lamarckii

(the percentage of shell with a given shell characters and formae in populations of different areas)


number of studied shells ®







shell characters and formae¯


Tulear, Mdagascar

Kenya, Zanzibar

Kilakarai, S. India

Phuket, Thailand

dorsal pattern

the dorsal spots are partially ocellated with purplish grey






dorsal spots are whitish to greyish, a few lateral ones excepted







confused: the dorsal pattern is confluent and/or displaced






deformed: unusual shell shape due to mechanical deformations






dilatata: the outer lip is dilated, shells mostly callused






“golden”: see text below; was described as Erosaria sharoni






incurvata: shells of unusual shape; was described as E. incurvata






pallida: shells with unusually pale coloration of the dorsum






rostrated: shells with unusually beaked extremities






saturated: shell very richly colored but markings as usual






suffused: shell with an enamel layer including particles of sand, mud







It follows from Table 1 that in the majority of shells from Mozambique (83%) the dorsal spots are ocellated with purplish grey. On the contrary, in 91% shells from Thailand these ocellations are absent. These data confirm the assumption that two geographically separated subspecies: E. lamarckii lamarckii (Gray, 1825), the nominal subspecies, and E. lamarckii redimita (Melvill, 1888) can be singled out because they conform to the criterion for diagnosing cowry subspecies.

Formae—nine formae of lamarckii are recognized in this study as listed in alphabethical order in Table 1.

Forma confused is characterized by the dorsal pattern irregularly confluent, displaced or distorted—Fig. 11. This forma is known in many cowry shells with an elaborated dorsal pattern: Erosaria macandrewi (Sowerby, 1870), Erosaria nebrites (Melvill, 1888), E. turdus (Lamarck, 1810) and many others.

Forma deformed is known in practically all cowry species—Fig. 14; it can be characterized by different kind of deformations usually of mechanical origin.

Forma dilatata: shell stunted, heavy, often small, margins calloused, thickened, or expanded—Fig. 9; it occurs in both subspecies and is especially frequent in the Phuket area.

According to the Prodrome “In redimita two ecological varieties can be distinguished in the whole area inhabited by the race: oblong shells…with angular margins, produced extremities, flattened base, finer and long columellar teeth and more conspicuous lateral spots than in the stunted callous shells (=inocellata Schil. 1930).” Calloused shells of E. lamarckii redimita, which are often also smaller than typical shells of the subspecies, can be treated as forma dilatata.





1.-3. E. lamarckii lamarckii, Mozambique


4. f. saturata




5.-7. E. lamarckii redimita, Thailand


8. f. pallida




9. f. dilatata


10. f. “golden”


11. f. confused


12. f. albinotic




13. f. incurvata


14. f. deformed + confused


15. f. rostrated


16. f. suffused


Martin, (1991) and Doneddu & Manunza (1993) reported an unusual population of E. lamarckii from Phuket, Thailand with small, calloused shells (f. dilatata).

Such shells are not only known in E. lamarckii redimita but also in the nominal subspecies and in several other species (Heiman, 2002) in the genus Erosaria.

Forma “golden”: shells are of an unusual appearrance because the upper layer of the dorsal pattern is absent—Fig. 10. One such shell has even been described as a new species Erosaria sharoni Walles, 1980 (now considered a synonym).

A similar phenomenon is known in shells of E. turdus pardalina (Dunker, 1852), Erosaria erosa (Linnaeus, 1758), Erosaria nebrites, Cypraea tigris (Linnaeus, 1758), and other cowry species.

Forma incurvata: the outer lip seems to be longer than the inner lip forming an “laughing” impression—Fig. 13. Shells of this kind have been described as a new species Erosaria incurvata Walles, 1980 (now considered a synonym).

Forma pallida: general coloring paler, markings often smaller and sometimes whitish—Fig. 8. The extreme case of this variety is f. albinotic when the dorsum has a very pale to almost white coloration—Fig. 12.

Forma rostrata: extremities produced, often recurved, base may be thickened or aperture abnormally dilated. I have only encountered this rare forma in shells from East Africa—Fig. 15.

Forma saturata: shell very richly colored to rather dark, but markings as usual—Fig. 4. This forma seems to be of clearly environmental origin and can be found in many cowry species.

Forma suffused: shell (or at least the dorsum) suffused with a uniform layer of rich white, gray, bluish, green, pink, fulvous, chestnut or blackish enamel often including particles of mud or sand—Fig. 16.

In practice, several formae may be combined (f. combined), for example, an unusual shell may be deformed with a confused dorsal pattern and so forth—Fig. 14.


I would like to thank Werner Massier (Namibia), Mike Woodcock (Canada), Rika and Fernand Dedonder (Belgium), Jean and Janine Demartini (France) for providing a background conchological material for this article, Henk K. Mienis (National Mollusc Collectios at the Department of Evolution, Systematics & Ecololgy, Hebrew University of Jerusalem and Zoological Museum, Tel Aviv University, Israel) for providing malacological information for this work and Solly Singer for reading and discussing the manuscript.


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