Forms of cribraria comma (Perry 1811) and of esontropia francescoi (Lorenz 2002)
Forms of cribraria comma (Perry 1811) and of esontropia francescoi (Lorenz 2002)
Author : Ronnie Watt, South Africa, 2005
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Forms of cribraria comma (Perry 1811) and of esontropia francescoi (Lorenz 2002) and a description of esontropia francescoi form mainland.
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| This paper presents a discussion of the following : |
| . A listing of the sp., ssp. and forms of the Cribrarula of Africa and the western Indian Ocean with their geographical ranges. . Is there a distinct form of cribraria comma? . Is esontropia francescoi form mainland indeed a ssp. of esontropia or should it be considered a ssp. of cribraria or even a form of cribraria comma? . A description of esontropia francescoi form mainland. . Could there be a distinct regional variation of esontropia francescoi form mainland? |
| THE CRIBRARULA OF AFRICA AND THE WESTERN INDIAN OCEAN |
| cribraria abaliena (LORENZ 1989) cribraria comma (PERRY 1811) esontropia esontropia (DUCLOS 1833) esontropia cribellum (GASKOIN 1849) esontropia francescoi (LORENZ 2002) esontropia francescoi form mainland (LORENZ 2002) pelliserpentis (LORENZ 1999) |
| DISCUSSION Material available to author in his own collection: c. comma (130), c. comma var. (3), e. francescoi (16), e. francescoi form mainland (34), intermediates of cribraria comma/esontropia francescoi (3) and varying numbers of specimens of c. abaliena, e. esontropia, e. cribellum and pelliserpentis. In addition, the author viewed specimens in the collections of Werner Massier (Swakopmund, Namibia), Clinton Matheson (Johannesburg, South Africa) and Vellie Veldsman and Laurie Smith (Pretoria, South Africa). |
| cribraria comma and its forms The shell is oval-pyriform with a callous base. The dorsal netting is dark brown and forms small, dense, regular lacunae. [Plate 1 and Plate 2] Marginal spotting is usually absent but specimens with faint spotting on the labral margin are known. [Plate 3] Much rarer are specimens with spotting on the columellar margin. [Plate 4] It is very variable in size, shape, dorsal coat colour and lacunae pattern. Specimens can be very elongated or globose and callussed. [Plate 5] The lacunae can be large or small and dense. Lacunae can be regular or irregular or diffused or even overlap similar to that of e. francescoi. [Plate 6] The pattern of the labral margin extends onto the margin but is frequently incomplete. [Plate 7] The dorsal coat colour can vary from dark brown to chestnut to pale-brown and even yellow-ish. [Plate 8] The dorsal ground colour ranges from creamy white to pale-purple. [Plate 9] |
| Lorenz refers to two variations of c. comma : c. comma Variation A The distribution extends from Tanzania to Somalia. The shells are elongate oval to cylindrical. The labral margin is rounded, hardly callous. The columellar margin is hardly callous. Marginal spotting is rarely found and if so, would be faint along the upper labral margin but absent on the base and columellar side. The ground colour is pale purple, showing very faint transverse banding. The dorsal netting is coarse, the coat colour is rather dark brown, forming small lacunae. He considers this to be the typical c. comma. c. comma Variation B |
| From the description and with specific attention to the references about labral margin spotting and the callussed labral and columellar margins, these specimens could only refer to e. francescoi form mainland which Lorenz described in 2002.
Merlin is of the opinion that specimens in his collection of Variation B from Mozambique and Madagascar, are similar to Variation A and that these are often confused with e. francescoi : "Dans la forme B toutes celles que nous avons du Mozambique et de Madagascar sont semblables à la forme A. Il semblerait qu'il y ait souvent confusion avec francescoi. |
| c. comma "form tanga" Lorenz makes a casual mention of this form. The locality is Prison Island in Tanga Bay off Tanzania. They are medium-sized (19.5 - 22.8 mm) with a blue-ish ground colour and chocolate dorsal colour forming round lacunae. The specimens show feint to distinct spotting on both margins. [Plate 10] Similar-looking specimens are also found on northern Unguja Island, Zanzibar, Tanzania. A sample of three specimens show lengths ranging from 14.2 - 18.8mm. Only one of these specimens shows spotting on both margins. Two further specimens from Shanzu Village and Diani Reef in Kenya also bear resemblance. All of the specimens except two have a dark base. The dark base is not seen in the Tanga Bay specimens. [Plate 11] The further discussion of this as a definite form of c. comma is inhibited by the lack of a sufficient number of specimens from these localities. The name "tanga" might well be invalid because the form could extend beyond Tanga Bay. |
| c. comma "form vallendum" I obtained a very globose specimen of c. comma from KwaZuluNatal Province, South Africa. It was dubbed "vallendum" on its original identification slip. The specimen was beach collected in 1985. I assume that the "val" in "vallendum" refers to the South African collector Val van der Walt from whom I obtained the specimen. It has some but not all of the features of e. francescoi form mainland. This should be considered an anecdotal exercise to identify a specimen with prominent differing features. However, if a case can be made out that this is indeed a specimen of e. francescoi form mainland, then it must be considered the earliest attempt to name the form. |
| c. comma cf c. abaliena Lorenz describes the shape of c. abaliena as oval, callous with the labral side rounded and callous and the columellar margin very callous and bent-up. The ground colour is pale orange with no conspicious transverse banding. The dorsal netting is wide, complete, pale brown and forms large lacunae. Specimens resembling c. abaliena in size and colour originate from Zanzibar, Tanzania and Reunion. These are adult shells. The length ranges between 11.5 mm - 16.2 mm. They differ from c. abaliena in that they are significantly more slender, do not have callous margins and the lacunae are smaller and more typical of c. comma. [PLATE 12] Is this a variation of c. comma? Or an intermediate between c. comma and c. abaliena? Lorenz accepts the sharing of the same geographical region of these two ssp. just as he acknowledges the co-existence of e. esontropia and e. cribellum and by cumingii cumingii (SOWERBY I 1832) and c. astarayi (SCHILDER 1971). |
| The taxonomic status of e. francescoi [Plate 13] Lorenz's description in "New Worldwide Cowries" reads: "The holotype is a moderately leightweight shell of elongate-pyriform shape, with slight development of callus around the margins but a rather thin base. The extremities are short and rather blunt. The aperture is wide and slightly curved behind. It widens anteriorly, the anterior canal is constricted. The labral teeth are evenly spaced, rather thin and extend slightly onto the lip. On the columellar side, the teeth are distant and rather thin, relatively few in number, with only the last anterior tooth being thickened. ... The extremities and margins are white, the orange embryonal shell is visible through the thin white basal callus. The dorsal ground is greenish-purple, with two paler transverse bands. The dorsum is covered with a dark reddish-brown coat forming numerous large, circular lacunae, many of which overlap. The dark coat ends abruptly towards the labral side, leaving about one-fourth of the dorsum exposed. Above the labral edge there are numerous distinct purple spots which form larger terminal spots towards the anterior extremity. Along the left side there are a few indistinct purple spots in the anterior third. The interior of the shell is dark purple. In the paratypes, the degree of marginal callosity varies considerably. There are slender, thin walled shells as well as very broad callussed specimens. The degree of marginal spotting varies too... the dorsal coat varies in the size and number of lacunae. In nearly all specimens studied, there is no pattern along the labral fourth of the shell." |
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Lorenz later revised this and assigned francescoi to esontropia rather than cribraria comma : In summary, Lorenz writes : However, spotting on the labral margin of Madagascar specimens, can be intensely dense and extensive to the point of having an appearance of a solid line. [Plate 14] Amongst malacologists there is disagreement about such a placement. Some would favour it to be a ssp. of cribraria, i.e. cribraria francescoi and there is also the opinion that it should be considered a form of c. comma, i.e. c. comma form francescoi. The latter opinion is that of Massier who motivates his arguement as follows: I can also conclude that francescoi should be called cribraria francescoi and not esontropia francescoi. Seeing that there are so many integrades with cribraria comma and that the geographical distribution overlaps I would call francescoi a form of c. comma and not a subspecies." Massier later added additional comments: The authorship of francescoi is disputed by Merlin and Philippe Quiquandon, France. They claim to have identified it as a ssp. of Cribrarula in advance of Lorenz's publication of his description. According to Merlin & Quiquandon they showed specimens of these shells that hailed from Madagascar, to Lorenz at the Paris Seashells Show 2002. Lorenz identified them as e. francescoi. The French then published their notes and photographs of specimens in Xenophora. They identified the specimens as e. francescoi but posed the question whether the ssp. should not rather be associated with cribraria. In an article in a later edition of Xenophora, Loïc Limpalaër endorses the Merlin & Quiquandon claim to have identified francescoi first: "As both the authors [Merlin & Quiquandon] explain they preceded the publication of this taxon by Felix Lorenz by a few weeks". And: "It was inadvertently christened in our columns of [Xenophoria] no 99: Cribrarula esontropia francescoi...". e. francescoi form mainland and a possible variation thereof Xenophora edition no 102 has photographs of specimens from Mozambique and Madagascar bearing the identification Cribrarula cribraria francescoi. The Madagascar specimen meets Lorenz's description of e. francescoi and the Mozambique specimen would then qualify as Lorenz's e. francescoi form mainland. Xenophora edition no 99 featured a photograph of a specimen from KwazuluNatal Province, South Africa which the authors labeled as c. comma. Because of the largely absent labral pattern and the spotting on both the labral and columellar margins, this specimen would also match Lorenz's e. francescoi form mainland. Based on the Lorenz and Xenophora photographs and with specific reference to my own collection of mainland forms (obtained from and verified as such by Lorenz and other sources), I wish to present the following as a discussion of and description for e. francescoi form mainland: 14 Specimens of e. francescoi and 34 specimens of e. francescoi form mainland were available for study. [Plate 15, Plate 16, Plate 17] I am indebted to Jean-Claude Merlin, France, for detailed notes of the e. francescoi form mainland specimens in his collection. Merlin concurs with most of my own observations. Following Lorenz's guideline, e. francescoi is restricted to Madagascar and e. francescoi form mainland is a relative found in Mozambique and the KwaZuluNatal and Eastern Cape Provinces, South Africa. Shape Massier concurs : "I agree with your statement that on average the mainland francescoi is more bulbous than their counterparts from Madagascar, but in-betweens do exist. Merlin also states this fact." Dorsal coat colour Dorsal base colour Transverse banding Lacunae pattern Labral pattern Marginal spotting Teeth Intermediates General comment The most southern specimens of e. francescoi form mainland With some exceptions, the specimens are of poor condition having lost most of the colour and lacunae pattern. The embryonic banding can be seen and the labral margin spotting is preserved. In most of the specimens the labral margin spotting is extensive, reaching from the posterior to the anterior extremities. Several specimens show very bold spotting. [Plate 18, Plate 19] Massier has specimens from the same region in his collection that differ as regards the marginal spotting: The shape and density of the lacunae and their overlapping are more reminiscent of e. francescoi from Madagascar. There is a far greater degree of lacunae overlapping than in the other e. francescoi form mainland specimens. In some specimens the netting pattern is vaguely similar to that of pelliserpentis. The three smallest specimens in the collection show heavy callussed margins. [Plate 20] The poor condition of the beached shells deters me from speculating whether this collection of specimens might constitute a valid variation of e. francescoi form mainland. On average they are, however, distinctly different from mainland specimens collected further north.
Plate 2: c. comma from various west Indian Ocean localities Plate 3: c. comma with labral margin spotting Plate 4: c. comma with columellar margin spotting Plate 5: Different shell shapes of c. comma Plate 6: Different lacunae forms and patterns of c. comma Plate 7: Labral margin patterns of c. comma Plate 8: Dorsal coat colours of c. comma Plate 9: Dorsal ground colours of c. comma Plate 10: c. comma "form tanga" Plate 11: Look-alikes of c. comma "form tanga" Plate 12: cribraria comma cf cribraria abaliena Plate 13: e. francescoi from Madagascar Plate 14: e. francescoi from Madagascar Plate 15: e. francescoi form mainland Plate 16: e. francescoi form mainland Plate 17: e. francescoi form mainland Plate 18: The most southern specimens of e. francescoi form mainland Plate 19: The most southern specimens of e. francescoi form mainland Plate 20: The most southern specimens of e. francescoi form mainland |
