17
Basin, S. guianensis van Bénéden, 1864 in the northern South America, and
S. brasiliensis van Bénéden, 1875 strictly at Guanabara Bay in southeastern Brazil
(Hershkovitz 1966).
During the 1960s, some doubts arose about the validity of such names and in
1963, Carvalho reports for the municipalities of Santos and Cananéia the presence
of a common dolphin known as the boto-da-baía-de-guanabara (Guanabara Bay
dolphin) (Monteiro-Filho et al. 2008a). In the following years, the doubt remained
on which name should be given to animals observed in several spots of the Brazilian
coast. After short considerations about the species, Rice (1977) started to consider
the existence of a single species (Sotalia fluviatilis), with two subspecies being one
restricted to the Amazon Basin (S. f. fluviatilis) and the other to the marine coast (S.
f. guianensis).
For 25 years the classification proposed by Rice (1977) remained, even with
some authors arbitrarily refusing the possibility of the subspecies. In 2002,
Monteiro-Filho et al. (2002) published a paper questioning the name given to marine
and fresh water animals of Sotalia. Authors used geometric morphometric to access
the skull shape of 104 individual from different locals of the Brazilian coast and
Amazon fresh waters. In addition to biological knowledge already published about
the species (see Monteiro-Filho et al. 2008a), the results point to two distinct biological units, and therefore repurposing the use of S. fluviatilis to describe fresh
water animals and S. guianensis for marine ones (Monteiro-Filho et al. 2002,
2008a).
Latter, molecular studies (Cunha et al. 2005) converged to the same conclusion.
These morphometric and molecular studies surely contribute so that researchers can
designate the results of their own studies to specific biological units. However,
despite of the academic importance, such studies are no news since researchers
described the species as separate units more than 150 years before. This fact brings
up the fantastic capacity of natural observation of such researchers of the nineteenth
and twentieth century.
Fig. 2.1 A Guiana
dolphin, Sotalia
guianensis, photographed
at Cananéia Lagoon
Estuarine Complex, State
of São Paulo, Brazil
(Photo: Caio N. Louzada)
2 Long-Term Monitoring of Dolphins in a Large Estuarine System of Southeastern…
Basin, S. guianensis van Bénéden, 1864 in the northern South America, and
S. brasiliensis van Bénéden, 1875 strictly at Guanabara Bay in southeastern Brazil
(Hershkovitz 1966).
During the 1960s, some doubts arose about the validity of such names and in
1963, Carvalho reports for the municipalities of Santos and Cananéia the presence
of a common dolphin known as the boto-da-baía-de-guanabara (Guanabara Bay
dolphin) (Monteiro-Filho et al. 2008a). In the following years, the doubt remained
on which name should be given to animals observed in several spots of the Brazilian
coast. After short considerations about the species, Rice (1977) started to consider
the existence of a single species (Sotalia fluviatilis), with two subspecies being one
restricted to the Amazon Basin (S. f. fluviatilis) and the other to the marine coast (S.
f. guianensis).
For 25 years the classification proposed by Rice (1977) remained, even with
some authors arbitrarily refusing the possibility of the subspecies. In 2002,
Monteiro-Filho et al. (2002) published a paper questioning the name given to marine
and fresh water animals of Sotalia. Authors used geometric morphometric to access
the skull shape of 104 individual from different locals of the Brazilian coast and
Amazon fresh waters. In addition to biological knowledge already published about
the species (see Monteiro-Filho et al. 2008a), the results point to two distinct biological units, and therefore repurposing the use of S. fluviatilis to describe fresh
water animals and S. guianensis for marine ones (Monteiro-Filho et al. 2002,
2008a).
Latter, molecular studies (Cunha et al. 2005) converged to the same conclusion.
These morphometric and molecular studies surely contribute so that researchers can
designate the results of their own studies to specific biological units. However,
despite of the academic importance, such studies are no news since researchers
described the species as separate units more than 150 years before. This fact brings
up the fantastic capacity of natural observation of such researchers of the nineteenth
and twentieth century.
Fig. 2.1 A Guiana
dolphin, Sotalia
guianensis, photographed
at Cananéia Lagoon
Estuarine Complex, State
of São Paulo, Brazil
(Photo: Caio N. Louzada)
2 Long-Term Monitoring of Dolphins in a Large Estuarine System of Southeastern…