Spondylopecten globosus (Quenstedt, 1843)
QUENSTEDT, F. A. 1843. Das Flözgebirge Württembergs. Mit besonderer Rücksicht auf den Jura. 560 pp. Tübingen (Laupp) [p. 476]
1843 Pecten globosus Quenstedt, 1843
1874 Pecten cordiformis Gemmellaro & Di Blasi, 1874
1898 Spondylopecten G. boehmi E. Philippi, 1898
1874 Pecten cordiformis Gemmellaro & Di Blasi, 1874
1898 Spondylopecten G. boehmi E. Philippi, 1898
Pecten globosus; F. A. Quenstedt, 1856-1858, Der Jura, plate 92, figure 20.
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«Beide Schalen sind aufgebläht, wie die gewölbte Schale des P. gryphaeatus der Kreide, und nähern sich insofern aufeinander geklappt der Kugelform, die Rippen markiert und nie dichotum, große Symmetrie, wie bei Pectunculus, auch stehen die Wirbel weit voneinander. Dem Pecten subpunctuatus sehr verwandt, nur werden sie viel größer.
Bemerkenswert sind die Formen welche dem Pecten aequicostatus Sow. (gryphaeatus SchI.) gleichen, und die namentlich im weißen Korallenkalke von Arnegg wie von Au bei Kelheim in so großer Häufigkeit vorkommen. Auch in den kieseligen Kalken von Nattheim fehlen sie nicht, und auffallenderweise erheben sich neben dem deltaförmigen Schloßmuskelloch zwei Zähne, von denen besonders der vordere sehr lange und kräftig wird.» FIEDRICH AUGUST QUENSTEDT, 1843
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«2. AMENDED DIAGNOSIS
Distinguished from all other species of S. (Spondylopecten) by the number of plicae (51-71).
3. AMENDED DESCRIPTION
Essentially similar to S. (S.) cardinatus. Differing by the diagnostic larger number of plicae (see Section 2), whose median value, if anything, oscillates phyletically (see Section 10), and by the generally lower umbonal angle and higher convexity. There is insufficient data from which to accurately assess the range of variation in the latter parameters. The lectotype of the species (see above) probably exhibits fairly typical proportions. The maximum height is 26.9 mm (STAESCHE, 1926).
4. DISCUSSION
QUENSTEDT's (1843) original hypodigm for 'P.' globosus is a matter of some doubt. A comparison with 'P.' subpunctatus MÜNSTER combined with a reference to very high convexity in the original description (see Section 1) suggests that it included forms referable to both S. (S.) subpunctatus and the species described in Section 3. This interpretation is borne out by the fact that the QUENSTEDT Collection (GPIT) used to contain two specimens labelled 'P.' globosus, one with moderate convexity and about 30 plicae and the other with high convexity and about 60 plicae, and by the fact that both specimens were figured by QUENSTEDT as 'P.' globosus in later works (1852, 1858). For the purposes or this work it is desirable to restrict QUENSTEDT's taxonomic species by designating one or other specimen as the lectotype. However, following Recommendation 74A of the ICZN ( N. R. STOLL et al.,1964) due weight is given in the choice to valid restrictions of the species by previous authors, as discussed below.
THURMANN and ÉTALLON (1862), DE LORIOL (1867), JOUKOWSKY and FAVRE (1913), PHILIPPI (1898), REMES (1903), FAURE-MARGUERIT (1920) and YIN (1931) all apply QUENSTEDT's specifc name to forms with about 30 plicae (see p. 99). However, only in the last four cases is it clear, from the fact that other specimens with about 60 plicae are referred to different species, that these authors actually restricted their concept of QUENSTEDT's taxonomic species to forms with about 30 plicae. In fact, PHILIPPI's citation of the specimen figured in pI. 92, fig. 20 of Der Jura (the form with about 60 plicae) as type ior his restricted concept of the species effectively re-expands his hypodigm to that probably envisaged originally by QUENSTEDT. BOEHM (1883), LISSAJOUS (1910), STAESCHE (1926), DECHASEAUX (1936) and YAMANI (1975) apply QUENSTEDT's specific name to forms with about 60 plicae. All but LISSAJOUS give a clear indication that their concept of QUENSTEDT's taxonomic species is restricted to such forms by referring other specimens with about 30 plicae to different species. STAESCHE suggests moreover that QUENSTEDT himself may have intended such a restriction in Der Jura. It is STAESCHE's contention that in the latter work (1858), in which 'P. ' aequatus, a new species with about 30 plicae is also figured, QUENSTEDT applied the name 'P.' globosus by mistake to an Illustration of the cardinal area of a form with about 30 plicae which he really meant to label as a second figure of 'P. ' aequatus. On these grounds STAESCHE draws the logical conclusion that in 1858 QUENSTEDT restricted his hypodigm for 'P. ' globosus to forms with about 60 plicae. There is however no a priori reason to think that QUENSTEDT made a nomenclatural error and furthermore there are no grounds for believing, as STAESCHE seems to imply , that QUENSTEDT intended such a restriction all along. The description in 1843 and the illustrations in 1852 belie this reasoning (see above). On the available evidence one must draw the conclusion that QUENSTEDT erected 'P.' aequatus as a species distinct from the original specimen of 'P. ' globosus with about 30 plicae. In summary it can be said that previous restricted usage of QUENSTEDT's taxonomic species is, on the basis of specimens described in the literature studied by the author, apparently equally divided between forms with about 30 and forms with about 60 plicae. Weight of numbers therefore gives no lead in the selection of an appropriate lectotype for 'P.' globosus. The first author to apply QUENSTEDT's specific name in a clearly restricted sense was BOEHM (1883) who used the name for forms with about 60 plicae. Therefore on grounds of historical precedence the original specimen with about 60 plicae is the most appropriate choice for the lectotype of 'P. ' globosus. Since this specimen appears to be the only one remaining of the two originally housed in the GPIT such a selection also avoids any possible need to designate a neotype. Accordingly the specimen with about 60 plicae (PI. 3, Figs. 22, 23) is herein designated as lectotype. As a result Spondylopecten G. Boehmi PHILIPPI, which was erected for this and another specimen (following restriction of QUENSTEDT's taxonomic species to the original specimen with about 30 plicae), would seem to become a junior objective synonym, and if so must be rejected. Non-synonymous and questionably synonymous usages of QUENSTEDT's specific name quoted in the synonymy are discussed on p. 99. All other usages are within the present author's hypodigm for S. (S.) globosus (see Section 3). 'P.' cordiformis GEMMELLARO and DI BLASI is inseparable from S. (S.) globosus by its inflation (C/L: 0.94) and number of plicae (56). Nevertheless BOEHM ( 1883) considered that the two species should be placed in separate genera (cordiformis in Pecten, globosus in Spondylus) on the basis of the lack of a cardinal area in the former and of a byssal notch in the latter. However, STAESCHE (1926) has pointed out that this is merely the result of poor preservation and that therefore the species cannot be separated at any level. Of the forms referred to GEMMELLARO and DI BLASI's species by YIN (1931) only one, with 60 plicae, is referable to S. (S.) globosus. The remainder, with 42-48 plicae, must be assigned to S. (S.) cardinatus.» JOHNSON, A. L. A. 1984. The palaeobiology of the bivalve families Pectinidae and Propeamussiidae in the Jurassic of Europe. Zitteliana, 11: 1-235, pls. 1-11. [p. 104, 105]
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Spondylopecten (Spondylopecten) globosus (Quenstedt, 1843); A. L. A. Johnson, 1984, The palaeobiology of the bivalve families Pectinidae and Propeamussiidae in the Jurassic of Europe, plate 3, figures 22-24.
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