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Steno bredanensis (rough-toothed dolphin)
Taxonomy
Delphinus bredanensis was named by Lesson (1828). It is extant.
It was synonymized subjectively with Steno rostratus by Gray (1846); it was synonymized subjectively with Steno frontatus by Trouessart (1898); it was recombined as Steno bredanensis by Miller and Kellogg (1955), Scheffer and Rice (1963), Hershkovitz (1966), Barnes (1977), Vidal (1991), Rice (1998), Mead and Brownell (2005), West et al. (2011), Perrin et al. (2013) and Jefferson (2021).
It was synonymized subjectively with Steno rostratus by Gray (1846); it was synonymized subjectively with Steno frontatus by Trouessart (1898); it was recombined as Steno bredanensis by Miller and Kellogg (1955), Scheffer and Rice (1963), Hershkovitz (1966), Barnes (1977), Vidal (1991), Rice (1998), Mead and Brownell (2005), West et al. (2011), Perrin et al. (2013) and Jefferson (2021).
Synonyms
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Synonymy list
Year | Name and author |
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1828 | Delphinus bredanensis Lesson |
1829 | Delphinus bredanensis Fischer p. 505 |
1829 | Delphinus planiceps Van Breda p. 236 figs. Pl. 1, 2 |
1841 | Sotalia santonicus Lesson p. 15 figs. Pl. 2, Fig. 1, 2 |
1841 | Delphinus reinwardtii Schlegel p. 27 |
1841 | Delphinus chamissonis Wiegmann p. 359 |
1843 | Delphinus compressus Gray p. 105 |
1846 | Delphinus compressus Gray p. 17 |
1846 | Steno compressus Gray p. 17 |
1846 | Steno fuscus Gray p. 44 figs. Pl. 26, Fig. 1 |
1850 | Delphinus oxyrhynchus Gray |
1850 | Steno compressus Gray p. 128 |
1850 | Delphinus oxyrhynchus Gray p. 131 |
1850 | Steno fuscus Gray p. 131 |
1866 | Steno compressus Gray p. 213 |
1866 | Steno fuscus Gray p. 239 |
1868 | Steno compressus Gray p. 4 |
1868 | Steno fuscus Gray p. 5 |
1876 | Delphinus perspicillatus Peters p. 360 |
1877 | Delphinus (Steno) perspicillatus Peters |
1889 | Steno perspicillatus True p. 25 |
1898 | Sotalia santonicus Trouessart p. 1027 |
1898 | Steno perspicillatus Trouessart p. 1029 |
1904 | Sotalia santonicus Trouessart p. 763 |
1904 | Steno perspicillatus Trouessart p. 764 |
1955 | Steno bredanensis Miller and Kellogg |
1963 | Steno bredanensis Scheffer and Rice p. 7 |
1966 | Steno bredanensis Hershkovitz p. 16 |
1977 | Steno bredanensis Barnes p. 323 figs. Table 1 |
1991 | Steno bredanensis Vidal p. 5 |
1998 | Steno bredanensis Rice p. 102 |
2005 | Steno bredanensis Mead and Brownell p. 734 |
2011 | Steno bredanensis West et al. p. 177 |
2013 | Steno bredanensis Perrin et al. p. 571 figs. Table 1 |
2021 | Steno bredanensis Jefferson p. 23 |
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If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.
Steno bredanensis Lesson 1828 [rough-toothed dolphin]
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Invalid names: Delphinus (Steno) perspicillatus Peters 1877 [synonym], Delphinus chamissonis Wiegmann 1841 [synonym], Delphinus compressus Gray 1846 [synonym], Delphinus oxyrhynchus Gray 1850 [synonym], Delphinus perspicillatus Peters 1876 [synonym], Delphinus planiceps Van Breda 1829 [synonym], Delphinus reinwardtii Schlegel 1841 [synonym], Sotalia santonicus Lesson 1841 [synonym], Steno fuscus Gray 1846 [synonym], Steno perspicillatus True 1889 [synonym]
Diagnosis
Reference | Diagnosis | |
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K. L. West et al. 2011 | In the wild, Steno bredanensis can most easily be distinguished from other small delphinids by a forehead that gradually slopes into a long and slender rostrum, lacking the demarcation that separates the melon and beak (Fig. 1). Although Stenella and the Indo-Pacific bottlenose dolphin (Tursiops aduncus) have a similarly long rostrum, they have the clear demarcation that is absent in S. bredanensis. The bottlenose dolphin (T. truncatus) has a much shorter rostrum and a dorsal fin that is less erect but may still be confused with S. bredanensis (Jefferson and Leatherwood 1993; Perrin et al. 2007).
The color pattern appears to vary according to geographic location and age of the individual (Miyazaki and Perrin 1994). S. bredanensis is gray in color with a slightly darker gray cape and often has distinctive white lips (Baker 1987; Jefferson and Leatherwood 1993). The darker cape is apparent from above the eye to the dorsal fin, gradually widening, and extending down the sides of the animal (Miyazaki and Perrin 1994; Fig. 1). The sides of the animal are typically a lighter gray color, and there may be white, pink, or yellow splotches or scarring on the tip of the rostrum, along the lower jaw, and in the ventral region. The mottled appearance is more frequently seen in older individuals, whereas uniform shades of gray are common in younger animals (Miyazaki and Perrin 1994). The skull (Fig. 2) may be confused with that of the Indo-Pacific humpback dolphin (Sousa chinensis) or Stenella but the skull of S. bredanensis is generally longer than those of Stenella (condylobasal length . 472 mm—Miyazaki and Perrin 1994). The rostrum of S. bredanensis is also long, approximately 60% of the condylobasal length, similar to the ratio between condylobasal length and rostrum in the spinner dolphin (Stenella longirostris), Pantropical spotted dolphin (Stenella attenuata), and striped dolphin (Stenella coeruleoalba—Perrin and Gilpatrick 1994; Perrin and Hohn 1994; Perrin et al. 1994). The mandibular symphysis of S. bredanensis is about one-third the length of the mandible, whereas the mandibular symphysis does not generally exceed 30% of the mandibular length in Sousa (Ross et al. 1994). The orbits of S. bredanensis also are relatively large (. 13% of condylobasal length) compared to Sousa. There are 19–26 teeth on each side in the upper jaw and 19–28 teeth in the lower jaw (Miyazaki and Perrin 1994). Tooth counts also can be used to distinguish between S. bredanensis and Sousa because S. chinensis has 30–38 teeth in each jaw and alveoli that are larger and more widely spaced (Van Waerebeek et al. 1999). The common name comes from fine, longitu- dinal ridges apparent on the surface of the teeth (Fig. 3). This character can be diagnostic when comparing teeth from S. bredanensis side by side with teeth from other delphinids. |