A Description of the Vexillifer Larvae of Pyramodon ventralis and Snyderidia canina (Pisces, Carapidae) with Comments on Classification

Abstract

The first identified vexillifers (4.4, 6.0 mm HL) and 2 juveniles (10.5, 11.4 mm HL) of Pyramodon ventralis are described and compared with vexillifer larvae of Snyderidia canina (3.6,5.7 mm HL). The presence of pelvic fins, a visceral cradle, and a greater number of pectoral-fin rays distinguishes larvae of P. ventralis from larvae of S. canina. Pyramodontine vexillifers are characterized as follows: a deep, compressed head and trunk with a depth at the first anal ray of 0.77-0.92 HL; a short predorsal distance of 1.12-1.27 HL; more than 24 pectoral-fin rays; a proximal vexillum radial with a descending anterior process, a wavy ventral contour, and a posterior process passing under the anterior dorsal-fin radials; a pronounced second neural spine; and long anal-fin radials. Identification of a vexillifer larva of Pyramodon establishes the vexillifer larva as a unique specialization of all Carapidae and reinforces the classification of Pyramodon as a close relative of Snyderidia.