![]() |
| Laimosemion laranja Abrantes, Lima, Nielsen, de Lira, da Silva & Berbel-Filho, 2026 |
Abstract
Based on morphological and molecular evidence, this study describes a new species of rivulid of the genus Laimosemion from the lower Rio Amazonas Basin in the south of the state of Amapá in northern Brazil. The new species, Laimosemion laranja sp. nov., exhibits a color pattern characteristic of the L. geayi species group, consisting of longitudinal rows of spots on the anterior portion of flank and oblique chevron-shaped bars on the posterior portion of flank. It can be distinguished from its congeners by unique combination of characters, including position of dorsal-fin origin relative to anal-fin rays, frontal squamation pattern of head, counts of transverse and longitudinal scale series, fin-ray counts, vertebral count, osteology of caudal fin, and number of neuromasts in infraorbital series. Partial sequences of the mitochondrial cytochrome c oxidase subunit I (cox1) gene indicates that the new species diverges genetically by 5.3% from its closest relatives, L. agilae and L. strigatus, by 9.2% from L. dibaphus, and 12.3% from L. geayi. We further discuss the systematic relationships within the L. geayi species group and the conservation status of the new species based on IUCN criteria, including recommendations for its conservation.
Key Words: Amapá State, Amazonas Estuary and Coastal Drainages Ecoregion, Amazonian ichthyofauna, conservation
Laimosemion laranja sp. nov.
Diagnosis. Laimosemion laranja differs from the six congeners of the L. geayi group by having eight scales in transverse series (vs.7 in L. dibaphus and L. strigatus, 9 in L. geayi, 9–10 in L. agilae and L. cladophorus, and 9–11 in L. mabura). It can be distinguished from all other congeners of the L. geayi group, except L. agilae and L. cladophorus, by dorsal-fin origin positioned on transversal plane through bases of 4th–6th anal-fin rays in both sexes (vs. of 7th–8th anal-fin rays). It differs from L. agilae by frontal squamation pattern of head (E squamation vs. F squamation) and from ...
Etymology. The specific epithet ‘laranja’ is a name with a dual allusion. It refers to the bright orange color pattern on males of the new species (‘laranja’ means the color, as it also means the fruit in Portuguese), and is also an homage to the municipality of Laranjal do Jari, founded on December 17, 1987, in the south of Amapá State, Brazil, from where the species is currently only found. A noun in apposition.
Yuri Gomes Abrantes, Sergio Maia Queiroz Lima, Dalton Tavares Bressane Nielsen, Fabio Origuela de Lira, Márcio Joaquim da Silva, Waldir Miron Berbel-Filho. 2026. A New killifish of the Genus Laimosemion (Cyprinodontiformes, Rivulidae) from Rio Cajari in the Brazilian Amazon. Zoosystematics and Evolution. 102(4): 1079-1088. DOI: doi.org/10.3897/zse.102.187659 [20 Aug 2026]


































