Comprehensive DescriptionRead full entry
“35. Parastenella Versluys, 1906
Not Stenella Gray, 1866b:213 [a cetacean].
Stenella.—Wright and Studer, 1889:56 [in part: S. doederleini, S. spinosa].— Kükenthal, 1915:151–152 [in part]; 1919:443–445 [in part: key to species]; 1924:303 [in part: key to species].—Aurivillius, 1931:289 [in part].
Stenella (Parastenella) Versluys, 1906:39, 45.
Candidella (Parastenella).—Bayer, 1956: F222.
Parastenella Bayer, 1961:295 [illustrated key to genus]; 1981b:936 [key to genus].—Bayer and Stefani, 1989:454 [key to genus].—Cairns, 2007a:245–247; 2007b:518, tbl. 2 [generic revision, tabular key to species].
Diagnosis. Colonies of most species planar dichotomous, occasionally slightly bushy. Calyces arranged in whorls (type species) of up to four, pairs or isolated, calyces standing perpendicular to the branch. Well-developed operculum present, the operculars prominently keeled (Figure 16f) on inner surface. Eight marginal scales present, alternating in position (offset; Figure 16a) from operculars. Most operculars bear an elongate, distal, concave to tubular extension (a fl ute; Figure 16a–b, d), although in some species these are missing from adaxial marginals. Abaxial body wall scales may also have distal flutes (Figure 16g). Each calyx completely covered with five to eight longitudinal rows of body wall scales (five in type species), their outer surfaces covered with small granules. Coenenchymal scales arranged in one layer. Tentacular rods are often present (Figure 16g).
Discussion. Originally proposed by Versluys (1906) as one of four subgenera of Stenella sensu Gray, 1870, the subgenus was raised to generic status by Bayer (1981b), who considered the alternation of marginal and opercular scales to be of generic significance. The genus was partially revised by Cairns (2007a), who provided a tabular key to the six species (Table 4). Characters used to distinguish species include colony shape, arrangement of calyces, size and presence of marginal flutes, and number of body wall scale rows.
Distribution. Known from all ocean basins except the eastern Atlantic and off continental Antarctica, 567–3,470 m.
Type Species. Stenella doederleini Wright and Studer, 1889, by subsequent designation (Bayer, 1956: F222). The type is deposited at the BM (18126.96.36.199), and a fragment of the type is deposited at the ZMA (Coel. 3085) (van Soest, 1979).”
(Bayer & Cairns, 2009)