Morphological features and molecular identification of African sicklefish, Drepane Africana (Osório, 1892) off the Niger Delta Coast, Nigeria

Abstract

African sicklefish, Drepane africana is the only member of the family Drepaneidae found and reported in Nigerian waters. Despite its prominence in catches there is a dearth of detailed published information on morphological features and molecular identification of the species off the Niger Delta coast. This study was carried out to assess its morphological, morphometric (truss and conventional) and meristic characters, as well as DNA sequence. Samples of D. africana (n=2,143) were collected between April, 2013 and September, 2015 from seven sampling stations off the Niger Delta coast, Nigeria. The morphometrics (conventional and truss) and meristic characters of the fish were studied. DNA sequencing of the samples were also carried out. Data were analyzed using descriptive statistics and Principal Component Analysis (PCA). There was no variation in the numbers of all the meristics characters counted except in the number of pelvic fin spine, anal fin spine and atlas. The mean of total length, body depth and pectoral fin were 26.6±5.5, 15.1±1.8 and 11.7±1.0 cm respectively. The first four principal components (PCs) of the truss measurement accounted for 93% of the variation in the population, PCA revealed that the observed differences mainly were from the posterior and dorsal part of the fish. The range of 98-100% definitive identity matches of the species with GenBank records shows that all the sequenced samples have been correctly identified as Drepane africana.