Pacific Guitarfish, Pseudobatos planiceps
Pacific Guitarfish, Pseudobatos planiceps. Underwater photographs taken in Zihuantanejo Bay, Guerrero, March 2018 and November 2023. Photographs courtesy of Ron Woheau, Zihuantanejo.
The Pacific Guitarfish, Pseudobatos planiceps, is a member of the Guitarfish or Rhionobatidae Family, that is also known as the Flathead Guitarfish and in Mexico as pez guitarra and guitarra del Pacifico. There are eight global members of the genus Pseudobatos, of which seven are found in Mexican waters, two in the Atlantic and five in the Pacific Ocean.
The Pacific Guitarfish has a shark-like body and a large triangular head that tapers to a long, pointed snout that incorporate the fused pectoral fins. Their discs are elongated being 1.3x longer than wide. The dorsal side is brown, gray or olive in color and the ventral side is white. The snout is pale brown and lighter between the 2 head crests and on each side. Some fish have 5 pairs of dark blotches along the back and base of the caudal fin. Some juveniles have white spots on their backs. Their head has 2 narrow central cartilaginous crests that are set close together for the front third and one spiracle that is smaller than the eye. The caudal fin does not have a lower lobe and is convex below; and, they have two equal sized dorsal fins. The have skin with a sandpaper texture with a row of small tubercles along the midline of the back, 2 groups on each shoulder and several around the eyes and spiracles.
The Pacific Guitarfish is a demersal coastal species that is found from the surface to depths up to 50 m (165 feet) over sandy substrate. They reach a maximum of 1.14 m (3 feet 9 inches) in length and 6.3 kg (13 lbs 14 oz) in weight. Reproduction is ovoviparious (aplacental viviparity) with embryos feeding initially on yolk and then receiving additional nourishment via indirect absorption of uterine flue enriched with fat, protein and mucus as from their months, with offsprings born live as miniature adults. The Pacific Guitarfish is considered to be rare and seldom seen by humans. The Pacific Guitarfish is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.
The Pacific Guitarfish is a resident of Mexican waters of the Pacific Ocean but has a limited range being found only from the Golfo de Tehuantepec south to Guatemala. The fish photographed below extends this known range northwards along the coast of mainland Mexico to the coastal waters off the State of Guerrero.
The Pacific Guitarfish is a straight forward identification that within its range in Mexico can only be confused with the Speckled Guitarfish, Pseudobatos glaucostigma (spiracle with two folds; covered with blue-gray spots) and the Whitesnout Guitarfish, Pseudobatos leucorhynchus (spiracle with two folds; transparent white snout).
From a conservation perspective the Pacific Guitarfish is currently considered to be Data Deficient. They are thought to be “uncommon” but in South American they are retained on a limited basis and sold commercially.