Geographic distribution of Thysanoteuthis rhombus ( Cephalopoda , Thysanoteuthidae ) on the Brazilian coast

Data on two female individuals of the diamonback squid, Thysanoteuthis rhombus , are presented with discussion of occurrences along the Brazilian coast.

possess similar measurements (Table 1) and represent the southern occurrence of the species on Brazil (Table 2) (Figure 1).
Despite the length of the Brazilian coast and the 200 miles of exclusive economic area offshore, the capture of Thysanoteuthis rhombus adults (Figure 2) in this country is rare.These are incidental and are part of the bycatch of fisheries targeting the ommastrephid squid Ommastrephes bartramii (Lesueur, 1821) (Haimovici and Peres 1991).There is no directed fishing fleet for T. rhombus in Brazil.Nevertheless, T. rhombus has been considered as a target species with commercial interest in the Canary Islands (Báez and Marrero 2007;Pérez et al. 2012).In Japan, the annual catch increased from 339 tons in 1989 to almost 6000 tons in 2001, and during 1998-2003 the average catch was close to 4900 tons (Bower and Miyahara 2005).In Brazil, their presence was generally recorded indirectly by larvae (Nigmatullin et al. 1995;Haimovici et al. 2002) or stomach contents with beaks and partially digested specimens (Santos andHaimovici 2001, 2002;Vaske 2005;Vaske and Lessa 2005).Their low incidence is seen by the lack of representativeness in the stomachs of oceanic fishes (Vaske 2005;Leite et al. 2009).
We observed that, despite the limited data available, distribution of mature individuals in the Atlantic South is connected to the Brazil Current, with northern and southern distribution between 23° and 36° S (Brunetti et al. 1999;Haimovici et al. 1989).The Brazil Current begins at about 10° S. Near 12° C the continental shelf becomes wider and this current separates slightly from the coast (Peterson and Stramma 1991).Here, Nigmatullin et al.

The diamondback squid, Thysanoteuthis rhombus
Troschel, 1857, is a large (100-130 cm mantle length), muscular, nektonic squid.The mantle is think and muscular, tapering to a blunt tip posteriorly.The fins are long, broad, and rhombic in form and occupy the entire length of mantle.The tentacular clubs have four rows of suckers, arm with two rows of suckers, buccal connectives attached to ventral borders of arms IV (Roper and Jereb 2010).As unique species of the family Thysanoteuthidae Keferstein, 1866, this species is a common circumglobal inhabitant of warm tropical and subtropical open waters.This species was already recorded at India (Batcha et al. 2009), Sulawesi (Billings et al. 2000), the Aegean (Salman et al. 2003;Salman 2012), Adriatic Sea (Bello 2009), Arabian Mediterranean (Chesalin and Zuyev 2002) and Caribbean Sea (Pulido-Lopez and Lopez-Pinto 2002;Salvat-Torres et al. 2009;Roper and Jereb 2010).
In the Atlantic Ocean, Thysanoteuthis rhombus occurs from latitude 30° N to 36° S and its southernmost distribution is bounded the displacement of the waters of the Brazilian Current (Brunetti et al. 1999).Thysanoteuthis rhombus has been known in Brazilian waters since 1985 but there is neither material deposited in scientific collections nor officially published records (Ferreira 1987).Records of both juvenile and adult individuals of T. rhombus from along the Brazilian coast are scarce, and for the Southern Atlantic Ocean, there are only three records in the literature (Haimovici et al. 1989;Haimovici and Perez 1991;Brunetti et al. 1999).Herein we report the presence of two adult specimens of the diamondback squid, T. rhombus, collected along the southern coast of Brazil.
The two female specimens were captured and collected by longline vessel at Mostardas, Rio Grande do Sul, Brazil (31°40′00″ S 49°27′00″ W) and are housed at the mollusc collection of the Museu de Zoologia da Universidade de São Paulo (MZSP 97741 and MZSP 97740).Measurements follow Jereb et al. (2010) and were taken with a measuring tape and a scale.The samples were fixed in 10% formalin solution and preserved in 70% alcohol.Both specimens Abstract: Data on two female individuals of the diamonback squid, Thysanoteuthis rhombus, are presented with discussion of occurrences along the Brazilian coast.(1995) recorded T. rhombus larvae.The Brazil Current separation from the continental shelf varies anywhere between 33° S-38° S but it is usually about 36° S (Podesta et al., 1991), where it collides with the north-flowing Malvinas (Falkland) Current.The Brazil Current is then, in part, deflected offshore east of Rio de la Plata, a region known as the Brazil-Malvinas Confluence Zone (Saraceno et al. 2004).We conclude that the distribution of the Thysanoteuthis rhombus is south of the confluence zone between the Brazil and Malvinas Currents.We also conclude that the presence of adult individuals indicate that this species can breed in Brazilian waters.

Table 1 .
Biometric data of the two adult specimens of Thysanoteuthis rhombus herein reported.

Table 2 .
Chronology of records of Thysanoteuthis rhombus in the Southern Atlantic Ocean.