Pectinella Verrill, 1897
VERRILL, A. E. 1897. A study of the family Pectinidae, with a revision of the genera and subgenera. Transactions of the Connecticut Academy of Arts and Sciences, 10: 41-95, pls. 16-21. [p. 68]
«Pectinella, gen. nov. Type, P. Sigsbei Dall.
Shell small, thin, swollen, nearly smooth, with convex and slightly unequal valves. Auricles very unequal, oblique, the anterior larger, with a deep byssal notch in the right valve, but without pectinidial teeth; posterior auricle small. The surface is smooth except for fine lines of growth. Camptonectes sculpture is not present. The texture is not hyaline.
The only known species is Pectinella Sigsbei (Dall), Bull. Mus. Comp. Zool., xii, p. 223, pl. iv, fig. 2, 1886. It was taken by the Blake Exped. in the West Indies, in 158 fathoms. This form differs so much from all the other divisions of Pectinidae that it seems necessary to form a new genus for it. In its swollen form, it approaches some of the species of Limopsis and allied forms.» ADDISON EMERY VERRILL, 1897
|
Pecten (Pseudamusium) Sigsbeei Dall; W. H. Dall, 1886, Report on the Mollusca, Part I. Brachiopoda and Pelecypoda. Reports on the results of dredging, under the supervision of Alexander Agassiz, in the Gulf of Mexico (1877-78) and in the Caribbean Sea (1879-80), by the U.S. Coast Survey Steamer “Blake”…., plate 4, figure 2.
|
Pectinella miyakoensis (Nagao); I. Hayami, 1965, Lower Cretaceous marine pelecypods of Japan, part I, plate 45, figures 2-11.
|
«Genus Pectinella VERRILL, 1897
Type-species.— Pecten (Pseudamussium) sigsbeei DALL, Recent, Caribbean Sea (original designation).
Remarks.— In the outline and many other characters "Camptonectes" miyakoensis NAGAO, 1934, and a few other Cretaceous pectinids, which show a Chlamys-like outline but lack external and internal radial ribs and a wide intermediate fasciole area, seem to be congeneric with Pecten (Pseudamussium) sigsbeei DALL, from the Caribbean Sea near Havana, a species for which VERRILL (1897) proposed the section Pectinella. VERRILL (1897) and THIELE (1935) treated Pectinella as a section of Palliolum, which they considered to be a subgenus of Propeamussium. Their classification, however, cannot be accepted here, because the three groups are at least generically distinct.
Crural ridges of Entolium-type are not developed in the type-species of Pectinella and P. miyakoensis, but a pair of shallow depressions on the antero- and postero-dorsal parts of the left valve of the latter species are comparable with those of Entolium. Therefore, I regard here Pectinella as a distinct genus of the Entoliinae, presuming the genus as a descendant of Entolium. Pectinella is considered to be related also to Syncyclonema MEEK, 1864, in view of the similar outline of the anterior auricle. However, prominent concentric ornamentation, which were reported to exist on the surface of the type-species of Syncyclonema, is absent in Pectinella. The precise characters of Syncyclonema are not as yet clarified, and the phylogenetic relationship between the two is an unsolved problem. Some authors have considered that Pectinella and Syncyclonema are more closely related to Pseudamussium H. and A. ADAMS, 1858 (type-species: Pecten hybridus GMELIN, 1792*) and Palliolum MONTEROSATO, 1884 (type-species: Pecten testae PHILLIPPI) including subgenus Delectopecten STEWART, 1930. These genera are also founded on small pectinids with nearly smooth internal and external surface and a more or less developed byssal auricle, although they are generally regarded as the members of the Pectinidae instead of the Amusidae. But the ratio of length/height and the apical angle are much larger and the byssal auricle is never salient above the hinge-line in these two genera. Moreover, in Palliolum the ctenolium is distinct and concentric undulations are developed on the surface.» * NORTH (1951) discussed the nomenclatural problems concerning Pseudamussium, and stated that the genus was formally established by H. and A. ADAMS (1858) and its valid type designation was first made by SUTER (1913).
HAYAMI, I. 1965. Lower Cretaceous marine pelecypods of Japan, part I. Memoirs of the Faculty of Sience, Kyushu University, [Serie D - Geology], 15 (2): 221-349, pls. 27-52. [p. 317, 318]
|