Species: Poecilia petenensis, Petén molly

Poecilia petenensis Günther, 1866

Petén molly

Head and body relatively slender, moderately compressed at rear; head depressed;front nostril not tubular; covering of eye not continuous with skin of head; mouth small, at front, slightly oblique, lower jaw slightly projecting, top jaw protractile; jaw teeth consist of an outer row of large backward curved teeth with expanded tips, and several rows of small pointed teeth; inner row of teeth conical; dorsal fin with long base, 14 (14-16 rays), origin over or before pelvic origin; pelvic origin well behind pectoral base, near anal fin; tip of pelvic fin of males swollen, elongate;  pectorals high on flank, 14 or more rays, 5th ray not scalloped in male; anal fin origin under (female) or a little behind (male) dorsal fin origin; 3rd anal ray unbranched; anal fin modified in male to form an elongate sex organ, that organ short & with a straight tip that has small spines, two hooks and a long  fleshy palp on underside; tail base relatively narrow; tail fin bluntly straight, that of male with a short triangular point on lower rear corner; scales smooth and relatively large, 28-30 lateral scales, 20 scales around tail base.