Pseudobatos planiceps

Pseudobatos planiceps is a guitarfish in the family Rhinobatidae, order Rhinopristiformes, and is a marine fish that lives close to the bottom ^[1],[2]. Garman described it in 1880 in the genus Rhinobatos; in 2016 the genus Pseudobatos was created for the American guitarfishes that had until then been placed in Rhinobatos ^[1],[3]. In Peru it is known as «guitarra» ^[2].

Its global category on the IUCN Red List is Vulnerable ^[4]. In northern Peru there is a coastal fishery aimed at this species ^[5].

Like all batoids, it is a cartilaginous fish with a flattened body and the gill slits on the underside of the head ^[6]. Its whole skin, back and belly, is covered with very small dermal denticles whose crown averages 0.15 mm long in females and 0.16 mm in males; unlike the 2 rays studied alongside it, it has no thorns but tubercles instead ^[6].

The tubercles form series: one around the eye reaching to the end of the spiracle, a continuous row running down the midline from the nape to the tail, one row between the two dorsal fins and, over the shoulders, two rosette-shaped groups on each side, the outer one smaller than the inner ^[6]. The authors of that 2022 Peruvian study conclude that examining these skin structures is a simple way to tell batoid species apart ^[6].

In 36 individuals bought at the Chorrillos fish terminal, in Lima, total length ranged from 27 to 125 cm, with a mean of 85 cm ^[7]. Within the family Rhinobatidae, the checklist of Peruvian chondrichthyans also lists 3 other species that it then placed in Rhinobatos (Rhinobatos glaucostigma, Rhinobatos leucorhynchus and Rhinobatos prahli) and Zapteryx exasperata ^[8].

For a long time it was credited with a range from Mexico to Chile, but a 2026 review of verified records, combined with a distribution model, concludes that it lives only in southern Ecuador, the Galápagos Islands, Peru and northern Chile, and that there is no evidence of it in Central America or northern South America ^[9]. That review puts the old range down to taxonomic confusion ^[9].

It appears in the updated checklist of Peruvian chondrichthyans, which brings together 115 species ^[8]. In northern Peru it is caught with bottom-set gillnets in Sechura Bay ^[10], and in Lima it has been bought at the Chorrillos fish terminal ^[7].

Between December 2012 and June 2014, 796 guitarfish were recorded as taken in 183 sets off northern Peru; most were adults and males outnumbered females ^[5]. Females averaged 83.4 cm in total length and males 91.1 cm, and the length–weight relationship showed that males and females grow differently ^[5].

In the Chorrillos sample, gathered between September 2009 and August 2010, there were 14 females and 22 males ^[7].

In a study of the stomach contents of 9 commercial shark and batoid species from northern Peru, with 865 stomachs holding food, the guitarfish fell in the group of species that eat mainly bony fishes and invertebrates in the coastal environment, both on the bottom and in the water column ^[11]. The other group, made up of open-ocean sharks, ate mainly cephalopods ^[11].

It hosts many parasites. All 36 individuals examined at Chorrillos carried at least one species, and 10 were found in total: 3 monogeneans, 3 tapeworms, 1 nematode, 1 leech and 2 copepods ^[7]. The most important was the nematode Proleptus carvajali, present in 80.5 % of the fish ^[7]. The gill monogenean Rhinobatonchocotyle pacifica, found in 63.8 % of those fish, was redescribed in 2019 from the type material and new specimens taken off Chorrillos, when its first DNA sequences were also published ^[7],[12].

Its global category on the IUCN Red List is Vulnerable ^[4]. Since 23 February 2023 it has been in CITES Appendix II, through the listing of the whole family Rhinobatidae, so its international trade is regulated under that convention ^[13].

The 2026 review argues that, with a much smaller range than was believed, heavy fishing pressure and no management of its own, its extinction risk is higher than the current assessment indicates, and it calls for the species to be reassessed and protected with specific measures ^[9]. The study of the coastal fishery in northern Peru, which found guitarfish in 86.3 % of the sets, was the first with fishery data specific to this species ^[5].

In the bottom gillnet fishery of Constante, in Sechura Bay, fitting green LED lights to the nets did not significantly change the catch of the target species as a group, guitarfish among them, and cut the bycatch of green turtles by 63.9 % ^[10].

It is a resource of Peru's small-scale fisheries. At Constante, in Sechura Bay, boats 6 to 10 m long fish with bottom gillnets made of panels 56.4 m long with a mesh of about 24 cm, set in the late afternoon and hauled the next morning; their targets are flounders, guitarfish and other rays ^[10]. In the northern Peruvian fishery studied from 2012 to 2014, the catch per unit effort was 12.6 guitarfish per kilometre per 12 hours ^[5].

In an illegal shrimp-trawl fishery in northern Peru, whose main fishing ground lies off Los Órganos, guitarfish was one of the 6 main commercial species included in the mobile app that fishers used to log their catches between October 2019 and March 2020 ^[14].

It is sold along Peru's seafood supply chain: a DNA barcoding study identified the species in a sample from a landing site in Tumbes, and found that a fillet sold as guitarfish in a supermarket in Trujillo was in fact Myliobatis chilensis ^[15].

Peruvian studies record it mainly where it is fished. Sechura Bay, in Piura, is a key area for the species according to fishery data from 2012 to 2014 ^[5]. It has also been bought at the Chorrillos fish terminal, in Lima, according to samples from 2009 and 2010 ^[7], and in 2019 and 2020 the shrimp-trawl fleet working off Los Órganos counted it among its main commercial species ^[14].