Sexual dimorphism in the Spotted Stinger Inimicus sinensis (Valenciennes, 1833) and notes on pore structures on the body

Abstract

Spotted stinger individuals, Inimicus sinensis, collected from Carles, Iloilo, Philippines exhibited previously-unreported sexual dimorphism. Thirty-three morphological measurements, including standard length, and fourteen meristic counts from 99 specimens (47 males and 52 females) were analyzed for sexual dimorphism. Most morphometric characters differed significantly between the sexes, whereas no differences were found in meristic counts. Dorsal and anal-fin and free pectoral-fin ray lengths were greater in male specimens. On the other hand, the head and body region were relatively larger in female specimens. Principal Component Analysis (PCA) extracted two principal components from significantly different parameters, which explained 62.29 % of the cumulative variances. Variations in the two major components resulted from: head width, upper jaw, lower jaw, snout, pre-dorsal, pre-anal-fin, and anal-fin base lengths in PC1 (45.65 %); and orbit diameter and anal-fin base length in PC2 (16.64 %). Additionally, a single anterolateral pore on the body and pores above the lateral-line are described, although no evidence of association with other organs was found.