After intense search for this particular cowry, the time has now come to showcase its amazing variations assembled thoughout the years.
The history of the Dawn Cowry
Palmadusta diluculum (Reeve, 1845)
(Mollusca: Gastropoda: Cypraeidae)
Martini & Chemnitz 1884:
Cypraea undata Lamarck.
Taf. 28. Fig. 2-5.
Testa ovlata vel ovato-ventricosa, umbilicata, sulbtus alba lateribus albidis fusco minusve dense punctatis, extremitatibus nigriccante-fusco marginatis, dorso violaceo-fusco, albo tri vel quinque zonatis, zonis fusco varie lineatim et maculatim undatis; apertura latiuscula leviter arcuata, columella convexa in medio pallido caeruleo maculata, dense et breve dentata; labrum incrassatum, dentibus minus numerosis et minus densis armatum; sinus lati, parum profundi. Variat colore rufescente zonis inconspicuis.
Long. 31, diam. max. 20, minus 15 Mm.
Cypraea undata Lamarck hist. nat. VII p. 393 (auf Argenville Conch. t. 18 f. N. Favanne t. 29 f. L Martini Conch. Cab. I t. 23 f. 226, 227. Encycl. mÈth. t, 356 f. 11). Seba Conch. llI t. 55 Nr. 19. Wood lnd. test. t. 17 f. 18. Gray Monogr. in zool. Journ. I p. 372. Deshayes Encycl. meth. III p. 829. Gray Desc. Cat. p. 12. Sowerby Conch. 111. f. 109. Kiener Coq. viv. t. 30 f. 3. Deshayes Lamarck 2 Ed. X p 524 et nota. Sowerby Thes. Conch. t. 19 f. 131ã134 non Chemnitz.
ã ziczac pars Linne-Gmelin, Schroeter, Lamarck Ann. du hlus. Dillwyn etc.
ã diliculum Reeve Conch. Ic. t. 14 f. 65.
Luponia undata H. et A. Adams Gen. of shells p. 267 Chenu Man. f. 1724. 1725.
Schale eifrmig oder bauchig-eifrmig, genabelt mit kurzen hinten schwrzlich-braun gerandeten Enden; vorn weiss mit einem grossen verwischten blulichen Placken auf der Spindel, Seiten weiss mit mehr oder weniger dicht stehenden braunen Punkten, die oft bis nahe an die Ml¸ndung herantreten; R¸cken violett-braun mit 3 bis 5 weissen Spiralzonen geschm¸ckt, die in Zickzack liniirt und gefleckt sind, diese Zeichnung ist recht manigfaltig variirt, zwei dieser Zonen sind als Hauptzonen anzusehen, die nebstdem obern Halsband oft allein vorkommen, dann tritt eineBasal- und schliesslich eine schmale Mittelzone dazu, oft ist die ganze Zeichnung verwischt und die Frbung zuweilen ganz hell rothbraun. M¸ndung nicht eng, leicht gebogen, Spindel etwas convex mit zahlreichen kurzen, dicht stehenden Zhnchen bewaffnet, whrend die des ziemlich breiten Mundrandes minder dicht stehen, strker und lnger sind; Ausschnitte ziemlich gross, aber weit und flach.
Vaterland: Zanzibar (Sow.), Seychellen und Chagos Ins. (Lienard), Natal (Krauss), Philippinen (Cuming) Museum Loebbeckeanum.
Es ist unfruchtbar den Namen C. undata Lam. wegen C. undata Chemnitz zu ndern, der eine junge Schale von C. mauritiana bezeichnet, ganz abgesehen davon dass Chemnitz nicht im Linneschen Sinne benannte, wenn dies auch manchmal so erscheint.
Here, Martini and Chemnitz propose that changing the name undata because it is preoccupied by undata Chemnitz (a juvenile mauritiana).
Original description:
Reeve 1845: Conchologia Iconica: Shells of Molluscous Animals Vol. III
Cypraea diluculum
Cypr. testa subpyriformi-ovata, ventricosa, apertura flexuosa, dentibus brevibus fortiusculis; dorso violaceo-castaneo, zornis duabus aut pluribus undulato-albis ornantis, lateribus basique albis, punctis perpaucis fuscis notatis, extremitatibus nigricante-castaneo-marginatis.
holotype figure
The Day-Break Cowrey. Shell somewhat pyriformly ovate, ventricose, aperture flexuous, teeth short, rather strong; back violet-chesnut, ornamented with two or more zones of zigzag white, sides and base white, marked with a very few brown dots, extremities edged with dark chesnut.
Cypraea ziczac (pars), Linnaeus, Martini. Cypraea undata, Lamarck (not of Chemnitz.) Hab. Philippine Islands; Cuming.
This ancient and well-known species requires to be distiuguished by a new name in consequence of the word undata, applied to it by Lamarck, having been already used by Chemnitz in reference to a shell which proves to be the young of the C. Mauritiana (Conch. Cab. vol. V. p. 102). It was confounded by Linnaeus and Martini with the C. ziczac, and is extremely well figured by the latter in the first volume of his Conchylien Cabinet, published in 1769.
Illustration from Sowerby's Thesaurus
Schilder & Schilder 1938
Prodrome of a Monograph on Living Cypraeidae
diluculum Reeve 1845 (Two races in the Western Indian Ocean).
The Lemurian virginalis (16.62.21.18) is smaller than the S.E. African diluculum (24.61.19.17) with the dorsal zones obsolete or quite dissolving, into fine zigzag lines beautifu1ly contrasting with the pure white ground-colour; the lateral and terminal spots are less accentuated to absent, the teeth are finer and more numerous, and the aperture is less curved behind.
a virginalis nov. (= buttoni Oldroyd 1916). S. 134; K. 30: 3 a.
Seychelles to Chagos, Mauritius and N. Madagascar; Aden ? (5, M-R,)
b diluculum Reeve 1845 (= undata Lam. 1822). S. 131-3 =
T. 16 : 33 ; K. 30 : 3 ; R. 65.
S E Africa: Natal to Zanzibar; Aden 7 (4, M)
Schilder & Schilder 1952
Ph. Dautzenberg's Collection of Cypraeidae
Palmadusta (Palmadusta) diluculum REEVE, 1845
Races: virginalis SCHIL. & SCHIL. 1938 diluculum REEVE, 1845 Distribution: ERY, AFR, LEM ERY, CAP, AFR Formula: 16(61)20:17 24(61)19:17 Base: flattened less flattened Aperture behind: straight, excepted in its hindmost part curved behind Dorsal zones mostly: obsolete or dissolving well marked (in adult shells only) Lateral and terminal spots: less accentuated to absent distinct
The first formula expresses the number of the dorsal zones (i = dissolving into zigzac-lines, 4=four dark zones, 3 = the two central zones confluent) / and their colour (pel = pellucid); the second formula indicates the size of the lateral spots / and of the anterior + posterior terminal spots.
AFR. Cap Ste. Marie (DECARY):1 ex. = virrginalis ?: about 18, dent. 19: 15, quite worn, so that we could hardly determine the species; aperture much curved behind, base convex, anterior terminal blotch absent.
LEM. Glorieuses (BUREAU B): 1 ex. = virginalis: 17(61)18: 17, i/pel (ferrugineous), terminal spots n + v.
LEM. Nosy Irandja (GIVENCHY B): 1 ex.=virginalis: 19(61)22:16,i/pel (ferrugineous),fine/s + i.
LEM. Diego Suarez (DECARY A): 2 ex. = virginalis: (both as worn as the shell from Cap Ste. Marie): about 14, dent. 22: 15 and 16, dent. 19: 16, lateral spots distinct.
LEM. Madagascar ex. f. = diluculum: 20-30, dent. 18-21:16-17, the adult shells are 4-3/bp-pn and n/n+n, largest shell exhibits the right lateral spots confluent; the young shell is i/pb and v/n + n.
LEM. Bourbon (ROSSIER R):1 ex. f. + 1 j. ex. f. = diluculum: 22, dent. 19: 17, 4/bp; 25, young, 3/pb, lateral spots wanting.
LEM. Mahe (CHERUBIM B): 2 ex. + 2 j. ex. + 1 jj. ex. = virginalis: 11, oliviform, i/bp, protoconch dark pb; 13-14(60)18-21: 14-17, 4-3/bp-pb and often fine/ n + n.
MEL. Nouv. Caledonie (BOUGIER A): 1ex.f.= diluculum: 23, 4/7 pel(orange) terminal spots n+ i.
GEN. Indian Ocean K: 10 ex.= diluculum: 19-28.
GEN Indopacific D: 7 ex. f.= diluculum: 21-29, 3/pb.
? Loc. ign. (BAVAY): 1 ex.= virginalis: 16, dent. 22: 18, dorsum typical, n/n+n.
? Loc. ign. (coll. ign.): 3 ex. = virginalis: 14, i / suffused with white, n/v + i; 15, 3/bp, v/i + i; 15(57)20: 19, i/b+p, fine/i + i.ã12 ex. = diluculum: 5 shells 19-23, zones obsolete;
G shells 20-25, with 4 or 3 zones, the largest shell is monstr.; 1 shell Z3, 4/pel (Ib).
DAUTZENBERGS shells show that all coasts of of Madagascar seem to be inhabited by virginalis only. The chief characters distinguishing the two races of diluculum consist in the size, in the straightness of the aperture, and in the dorsal markings, while the difference in dentition and in the terminal spots is not essential.
Burgess 1970 (and 1985)
The Living Cowries
35. CYPRAEA DILUCULUM Reeve, I845
Conch. Icon., Pl. I4, f. 65
Cypraea buttoni Oldroyd, I9I6, The Nautilus, Vol. 29, No. 9, pp. I07-I08
Cypraea undata Lam., I822, sans vert., Vol. 7, n. 40, p. 393
Palmadusta (Palmadusta) diluculum virginalis Sch.-Sch., I938, Proc. Mal. Soc., Vol. 23, p. I60
Pl. 7 f. F,Fl,G 32-0 to I3-6 mm (4)
distribution map (1985)
Certainly Cypraea diluculum Reeve is one of the most spectacular species (Figs. F,F1) in the animal world. The contrast of color is well shown in the illustration. The variation (Fig. G) with a pure white unspotted base, Palmadusta (Palmadusta) diluculum virginalis Sch.-Sch. I938, has been found side by side under the same coral block with the more common C. diluculum on one occasion by Mr. Fred Mehta of Zanzibar (personal communication). The animals in these two specimens have been preserved. I doubt that study of the soft parts, which were grossly the same, will show significant differences.
Animal: The animal is jet black. The mantle in preserved shells appears thin and smooth. In Kiunga, Kenya, Ken Sargent reported the shell among mangrove roots in very quiet water (un published report). The animal there was also jet black.
Habitat: This cowrie is found in shallow water in dead coral heads and under stones and coral slabs on a hard reef. Range: Cypraea diluculum is found in Mauritius, in Zanzibar, in Mozambique, and on the African coast between these areas. It has also been reported from the Seychelles and southeast Africa.
Lorenz (1999)
Kauris von Ostafrika (Schr. Malak.)
Lorenz & Hubert (2000)
"A Guide to Worldwide Cowries"
In our book, we dedicated a full colour plate only to P. diluculum, but the information in total was still superficial....
Now lets get to the point
An Update to the knowledge of Palmadusta diluculum
The animal of Palmadusta diluculum has been described by Burgess (1970) but to my knowledge, never has a living animal been illustrated. The photos confirm the description given by Burgess. The papillae are very fine and branched. The animal resembles P. clandestina, which apparently is the closest relative, as it occasionally interbreeds with diluculum (see below).
The radula has been illustrated by Bradner and Kay (1996) and by me in 1999, but till today I had no opportunity to study in detail the radulae of diluculum in comparison to d. virginalis. The habitat was also described by Burgess, I have found the species in sandy to muddy areas, under small stones and pieces of coral, in the intertidal.
Msasani Bay, Dar-es-Salaam.
It appears that the species occurs in seasons, with long intervals in which it is very rare. It is widespread throughout the western Indian Ocean, but only in two areas it is common: Pemba Island and Zanzibar Island. Morphologically, there are three branches into which the species can be split: the classic diluculum-branch comprises shells with dense basal spotting, a dark stripe over the anterior extremity, and by the white dorsal zigzag-bands being narrower than the dark component, which dominates. Asecond branch, which has largely been omitted in literature, was described as magnifica Coen 1949. These shells are dark spotted basally, the dark stripe on the anterior terminal is present, but the dorsal colour components are equally white and dark, making the shell look much brighter. This form, in contrary to typical diluculum, is commonly found as callous shell. Finally, the third branch comprises the totally unspotted shells we know as virginalis. The status of this taxon has been subject of many discussions, as it occurs alongside with diluculum, but only in certain places.
left: diluculum, middle: magnifica, right: virginalis
The distribution of these three forms is not homogenous, which implies that they are not mere individual variations but genetically determined. Another factor that speaks in favour of this is that magnifica is the rarest form. If virginalis and diluculum were extremes of just one variable species, the intermediate form should be most common.
Distribution of diluculum
distribution of magnifica
distribution of virginalis
What these three really are in respect of their systematic position cannot be said at this stage, but at least it is known what they look like: the following gallery will illustrate their beauty and characteristic features.
Even though these maps suggest it, diluculum in NOT found on Mauritius itself, but on St Brandon Shoal, 450 km northeast, which is part of the Mauritius Outlying Territories.
first uploaded in August 2000.
