Somalipecten lessepsi (Fuchs, 1878)
FUCHS, T. 1878. Die geologische Beschaffenheit der Landenge von Suez. Denkschriften der kaiserlichen Akademie der Wissenschaften [mathematisch-naturwissenschaftliche Classe], 38 (2): 25-42, pls. 1-3. [p. 40, pl. 2, figs. 2a, 2b]
1878 Pecten lessepsii Fuchs, 1878
1878 Chlamys (Aequipecten) suezensis Fuch, 1878 [nomen nudum]
1878 Chlamys (Aequipecten) suezensis Fuch, 1878 [nomen nudum]
T. Fuchs, 1878, plate 2.
|
«Es liegen mir von dieser neuen Pecten-Art vier Klappen aus den gehobenen Strandterrassen nordwestlich von Suez vor, welche jedoch leider sämmtlich rechte Klappen sind. Dieselben sind mässig gewölbt, von kreisförmigen Umriss, mit 10-11 regelmässigen Radialrippen bedeckt. Rippen flach gewölbt, doppelt so breit als die dazwischen liegenden Furchen, glatt oder doch nur mit einer äusserst schwachen Längsstreifung versehen. In den Zwischenfurchen liegen feine shuppige Radiallinien, welche jedoch bisweilen auch ganz fehlen oder nur auf zwei Schuppenreihen reducirt sind, welche die Ilauptrippen zu beiden Seiten begleiten. Die Ohren sind kurz, breit und glatt, das rechte mit einem seichten Byssusausschnitte, Bandgrube breit, dreieckig. Innenfläche der Schale den Rippen entsprechend mit Radialfurchen versehen, welche in der Mitte der Schale ziemlich seicht sind, am Rande aber plötzlich tief werden. In der Mitte der Schale sind sie überdies meist durch eine dünne Kalklamelle verdeckt.
Längendurchmesser: 67 Mm., Querdurchmesser: 70 Mm. Von den beschriebenen lebenden Arten scheint der vorhergehenden am nächsten P. solaris Born, (siche Philippi, Neue und wenig gekannte Conchylien, I, p. 202, Tab. 2) von Amboina zu stehen, doch hat diese Art zahlreichere (15) und schmälere Rippen, und sind die Rippen mehr abgerundet. Aus dem Rothen Meere ist mir keine Art bekannt, welche der in Rede stehenden nahe stehen würde. Ich erlaube mir, diese neue Art dem genialen Schöpfer des grossen Unternehmens der Durchstechung der Landenge von Suez, Herrn F. v. Lesseps zu widmen.» THEODOR FUCHS, 1878
|
«Le type de ce groupe: Ch. Lessepsi FUCHS (1878, Suez [64], p. 40, pl. II, fig. 2 a, 2 b) provient d'une terrasse sableuse à 6 km. au NW de Suez. En synonymie avec lui, entre le P. Fischeri VASSEL (non Zittel) (1884, Description d'une nouvelle espèce de Pecten fossile du Canal de Suez. Journal de Conchyliologie, t. 32, p. 331 et 1885, Journal de Conchyliologie, t. 33, p. 46, pl. III, fig. 1), que nous avons pu examiner au Laboratoire de Paléontologie du Muséum de Paris. Nous le figurons pour donner une illustration des caractères généraux du groupe (pl. XX, fig. 1 a, 1 b, 1 c).
Cette espèce est signalée dans le Pliocène et dans le Quaternaire de Suez, du Sinaï, de différents points des rivages de la mer Rouge, du Golfe Persique près de Bardistan, Elle n'existe plus actuellement, et ses affinités sont uniquement indo-pacifiques. Autour de Ch. Lessepsi viennent se grouper les espèces suivantes: 1) Ch. isthmica FUCHS (1878, Suez [64], p. 40, pl. Il, fig. 1 a-1 b), qui a la même répartition stratigraphique et géographique.
2) Ch. Leesi COX (1929, Ostreidae and Pectinidae [199], p. 197, pl. XI, fig. 4.; pl. XIII, fig. 5 a, 5 b), dans le Pliocène des îles Mugersim (Mer Rouge), est bien proche de la précédente. 3) Ch. farsanensis COX (1929, loc. cit., p. 196, pl. XIII, fig. 2), dans le Quaternaire des îles Farsan (Mer Rouge). n'est connue que par une valve gauche. 4) Chlamys Humei COX (1929, loc. cit., p. 198, pl. XII, fig. 3) n'est connue que par deux valves droites: l'holotype du Pleistocène de l'W de Suez et une seconde du Pleistocène de l'Attaka, faisant partie des collections de l'Université de Lyon. Elle corrrespond peut-être simplement à la valve droite de l'espèce précédente. 5) Ch. sudanensis COX (1929, loc. cit., p. 197, pl. XI, fig. 1 a, 1 b, 1 c), du Pliocène des iles Mugersim sur la côte du Soudan égyptien, est remarquable par sa forme très convexe. 6) Ch. Wyllei COX (1929, loc. cit., p. 199, pl. XIII, fig. 4 a, 4 b), de la plage soulevée de Jebel Titaweb (côte du Soudan égyptien), est le terme exlrême de la série, n'ayant plus que 5 larges côtes à la valve gauche. Aucune des espèces précédentes ne pénètre dans la Méditerranée. Le seul groupe de cette région lui ressemblant un peu par la disposition des côtes est celui de Chlamys glabra. Des cr'actères importants, de la face interne principalement, que M. Cox a déjà soulignés, séparent ces deux séries. Dans le groupe de Ch. Lessepsi, les côtes internes sont bien saillantes, l'appareil cardinal est robuste, bien en relief. Il ne nous semble pas que les deux groupes soient en relation.
Le groupe de Ch. Lessepsi appartient donc à une toute autre région; il est uniquement indo-pacifique. Le traiter en détail serait sortir des limites de notre travail. Il était cependant intéressant de le signaler à l'attention des chercheurs, car la plupart de ses espèces ne sont connues que par un petit nombre d'exemplaires. En outre, il nous montre qu'au Néogène récent le domaine indo-pacifique était, comme actuellement, totalement différent des mers européennes, par sa faune de Pectinidés.» ROGER, J. 1939. Le genre Chlamys dans les formations néogènes de l'Europe. Conclusions générales sur la répartition géographique et stratigraphique des Pectinidés du Tertiare Récent. Mémoires de la Société Géologique de France [Nouvelle série], 17 (2-4):1-294, pls. 1-28. [p. 149]
|
Chlamys Lessepsi Fuchs; J. Roger, 1939, Le genre Chlamys dans les formations néogènes de l'Europe, plate 20, figures 1a-1c.
|
«Fuchs' type-specimen was a right valve with about eleven ribs, twice as broad as their interspaces ; a closely comparable specimen (L. 37816), from Mugersim Island, is figured in the present paper (PI. XI, figs. 1a, b). This latter specimen was associated with another (L. 37819) ornamented with thirteen ribs, separated by interspaces nearly as broad as themselves. A similar variability is evident among the specimens which I have examined from several Red Sea localities, and also from Persia. I have therefore no doubt at all that Vassel's P. fischeri, separated from P. lessepsi because of trifling differences (chiefly the possession of one or two more ribs) is a synonym. In any case, as shown above, the name had been used previously by Zittel for a New Zealand fossil. The following is a full description of Ch. lessepsi and its variations.
The shell is cquivalve and suborbicular, with its length slightly in excess of its height in full-grown specimens, but with the height greater than the length in earlier stages of growth. It is occasionally equilateral, but usually inequilateral to a varying extent. The inflation is usually slight, but also varies, and one right valve (L. 37819), from Mugersim Island, is fairly gibbous. The dimensions of a typical right valve (L. 51297), from Abu Mingarh, are: Length 95 mm., height 91 mm., inflation 17 mm. Those of the comparatively strongly inflated right valve just mentioned are: Length 75 mm., height 70 mm., inflation 21 mm. The number of ribs, counted near the umbo (the lateral ones may become obsolete), varies from ten to fourteen, most specimens having from eleven to, thirteen. The interspaces are usually narrower than the ribs, being sometimes less than half, but normally about two-thirds, qf their width. Specimens in which the interspaces arc of about the same width as the ribs are, however, not uncommon (cf. PL. XI, fig. 2). In specimens where the ribs are comparatively wide, they are flattopped, except near the umbones, but, in specimens where they are narrow, they are very prominent and convex. In some specimens the whole of the surface of the shell is ornamented with imbricating growth-lamellse, but when these are absent the ornamentation is seen to consist of fine longitudinal threads, which are most conspicuous in the interspaces and near the lateral margins. The ears are variable in size and shape; usually they are ornamented with a few radiating riblets. In immature specimens the byssal sinus is deep and a ctenolium is present; in larger specimens the ctenolium has become obsolete and the sinus shallower. The right anterior ear is not bordered by any rib-like swelling, such as is developed in Ch. isthmica. Internally, flat ribs, sharply limited by ridges near the ventral margin, correspond to the interspaces of the exterior. From each of the lower corners of the ligament-pit there originates a ridge which is sub-parallel to the hinge-margin for some distance before it curves up to meet the end of the hinge-margin; this ridge limits the hinge-plate. The cardinal crura are very conspicuous in immature specimens, although they tend to become rather obsolete in full-grown examples. In the right valve they consist of a pair of narrow ridges, sometimes bifid distally, making a small angle with the hinge-margin, and a pair of short, thick triangular ridges between these and the margins of the ligament-pit, which are sharply defined by a third pair of ridges. In the left valve the ridges correspond to the spaces between those of the right valve and the ligament-pit is less sharply limited. The auricular crura are fairly strong in some specimens. Young specimens of this species are very similar to the typical variety of the Zanzibar Pliocene species, Ch. werthi (E. Philippi) (see Cox, 1927, pl. xvii, figs. 5 and 8), but they have not the interstitial riblets usually found in that species. The living Indian Ocean species of the group of P. flabellatus, Lamarck (P. leopardus, Reeve), bear some resemblance to Ch. lessepsi, but they are inequivalve, and their ribs are much more depressed.» COX, L. R. 1929. Notes on the Post-Miocene Ostreidae and Pectinidae of the Red Sea region, with remarks on the geological significance of their distribution. Proceedings of the Malacological Society of London, 18: 165-209, pls. 11-13. [p. 193, 194]
|
Chlamys (Aequipecten) lessepsi (Fuchs); L. R. Cox, 1929, Notes on the Post-Miocene Ostreidae and Pectinidae of the Red Sea region, plate 12, figure 2.
|
«Shell suborbicular, sometimes slightly inequilateral, almost equivalve. Right valve moderately convex, furnished with 11-13 regular, radial ribs wich are prominent and evenly convex near the umbo, but become flattened towards the ventral margin; nearly trwice as wide as the interspaces which separate them.
The ribs are smooth or bear faint longitudinal striae, which are more pronounced in the furrows and on the anterior and posterior margins of the valve. Left valve with convexity about equal to or slightly less than that of the right valve, and bearing an equal number of rather more prominent ribs which are about half as broad as the interspaces. Longitudinal striae less marked except along the posterior margin, where several are grouped together to form a subsidiary rib. Both valves ornamented with numerous closely-set concentric striae with occasional more strongly-marked growth halts. Ears fairly large, subequal, ornamented with fine radial striae crossed by concentric threads. The right anterior ear with a shallow byssal notch but no ctenolium. Interior of both valves with prominent flat ribs corresponding to the external furrows. Along the ventral border they become slightly concave with raised margins. Remarks. The original description of this species given by Fuchs, was admittedly imperfect, being based on right valves alone, but through the kindness of Mr. L. R. Cox I have been enabled to compare the Persian shells with specimens from Suez preserved in the Natural History Museum, South Kensington, and there is little doubt thaf the two forms are inseparable. The Persian examples, however, seem to possess one or two extra ribs, and the longitudinal striae are less clearly marked than in the Egyptian specimens. In both instances they are associated with Pecten vasseli. The striation on the ears was evidently not visible in Fuchs's shells, but it is present in all the specimens that I have examined. Horizon. Pecten vasseli-beds (topmost beds of Mio-Pliocene series).» DOUGLAS, J. A. 1928. Contributions to Persian Palaeontology, III. 19 p., pls. 8-15. The Anglo-Persian Oil Company Lts. Printed at The Holywell Press, Oxford. [p. 5, 6]
|
Aequipecten lesseppsi [sic] (Fuchs.); J. A. Douglas, 1928, Contributions to Persian Palaeontology, III, plate 9, figures 1, 2; plate 11, figure 2.
|