New records of the occurrence of Megaleporinus macrocephalus (Garavello & Britski, 1988) (Characiformes, Anostomidae) from the basins of the Itapecuru and Mearim rivers in Maranhão, Northeastern Brazil Author Almeida, M. S. Universidade Estadual do Maranhão - UEMA, Departamento de Química e Biologia, Programa de Pós-Graduação em Recursos Aquáticos e Pesca, São Luís, MA, Brasil Author Moraes, P. S. S. Universidade Estadual do Maranhão - UEMA, Laboratório de Genética e Biologia Molecular - GENBIMOL, Caxias, MA, Brasil Author Nascimento, M. H. S. Universidade Estadual do Maranhão - UEMA, Centro de Ciências Agrárias - CCA, Programa de Mestrado em Ciência Animal - CCMA, São Luís, MA, Brasil Author Birindelli, J. L. O. Universidade Estadual de Londrina, Departamento de Biologia Animal e Vegetal, Londrina, PR, Brasil Author Assega, F. M. Universidade Estadual de Londrina, Departamento de Biologia Animal e Vegetal, Londrina, PR, Brasil Author Barros, M. C. Universidade Estadual do Maranhão - UEMA, Laboratório de Genética e Biologia Molecular - GENBIMOL, Caxias, MA, Brasil Author Fraga, E. C. Universidade Estadual do Maranhão - UEMA, Departamento de Química e Biologia, Programa de Pós-Graduação em Recursos Aquáticos e Pesca, São Luís, MA, Brasil text Brazilian Journal of Biology 2022 e 232868 2020-06-15 82 1 6 http://dx.doi.org/10.1590/1519-6984.232868 journal article 298203 10.1590/1519-6984.232868 6239dea8-6764-4071-b423-ed8f0b1b85e4 1678-4375 11494278 3. Results On the Mearim River , one M. macrocephalus specimen was collected on the lower course of the river at Laje dos Currais , in the municipality of São Mateus , during the flood season, while two specimen was obtained on the middle course of the river in the town of Pedreiras during the dry (low water) season. The M. macrocephalus specimen was collected at the locality of Pé da Serra in the municipality of Caxias during the dry season. The four M. macrocephalus specimens ( Table 1 ) present a characteristic coloration pattern, with a darker superior half of the body, three large black spots on each flank, and dark lines between the rows of scales ( Ramirez et al., 2017 ). The body is robust, and the mouth terminal, with three teeth in the pre-maxillary bone and three teeth in the dentary bone ( Figure 2 ). The specimens have 42–43 scales in the lateral line, seven rows of scales between the lateral line and the origin of the dorsal fin, six rows of scales between the lateral line and the origin of the pelvic fin, and 16 rows of scales around the caudal peduncle. These characteristics, together with the morphometry of the specimens, are fully consistent with the descriptions of M. macrocephalus published Garavello and Britski (1988) and Britski et al. (1999) , and leave no doubt with regard to the identity of the taxon. Figure 2. Megaleporinus macrocephalus , MZUEL 20221, 387.10 mm SL. Table 2. Similarity percentage obtained by comparing the sequences of the COI gene on the BOLDSystems platform (The Barcode of Life Data System) for the M. macrocephalus species from the Itapecuru and Mearim rivers, Maranhão, Brazil, identified morphologically and which were confirmed with the molecular data.

Identificação
Código	N	Taxonômica	Molecular: Bold
MEA 831	1	M. macrocephalus	M. macrocephalus (99. 66%)
MEA 835	1	M. macrocephalus	M. macrocephalus (99. 66%)
MEA 836	1	M. macrocephalus	M . macrocephalus (99. 66%)
LEP 158	1	M. macrocephalus	M. macrocephalus (99. 66%)

Four COI sequences were obtained, one from the specimen collected from the Itapecuru River, and three from the specimens obtained from the basin of the Mearim River. Comparisons with the sequences available in the BOLDSystems database confirmed the morphological identification of the specimens.The COI sequences obtained from the specimens collected in the present study were more than 99% similar to that of M. macrocephalus from the basin of the Paraná River ( Table 2 ). This value is well within the 2% threshold for the identification of fish species by DNA barcoding ( Ward et al., 2009 ; April et al., 2011 ; Carvalho et al., 2011 ; Mabragaña et al., 2011 ; Castro Paz et al., 2014 ).