Fishes · Rays · Guitarfish

Whitespotted Guitarfish

Rhinobatos punctifer Compagno & Randall, 1987

89 cm70-150 mCITES IINear Threatened

751

The Whitespotted Guitarfish (Rhinobatos punctifer) is a key species inhabiting marine benthopelagic environments, with a depth range spanning from 70 to 150 meters. It is known to reach a maximum length of 89 cm. Predominantly demersal, it is found inshore on the continental shelf up to a depth of 70 meters, where it primarily feeds on small crustaceans and fish.

This species undergoes ovoviviparous (aplacental viviparous) reproduction, wherein embryos initially subsist on yolk, subsequently obtaining additional nutrients from uterine fluid enriched with mucus, fat, or protein through specialized maternal structures. It produces litters of up to seven pups, maturing at an approximate length of 62 cm and measuring about 25 cm at birth.

The Whitespotted Guitarfish can be identified by the following morphological characteristics: a wedge-shaped disc with a width constituting 29-34% of the total length (TL) and a length 1.2-1.3 times the width. The snout is relatively short, with a length 2.2-2.6 times the inter-spiracular distance, and 3.6-3.9 times the interorbital width in males (2.9-3.4 times in females). The orbit diameter is 1.2-1.7 times the spiracle length, and the nostrils are weakly oblique, their length being 1.3-1.9 times the interna nasalis distance. The mouth, narrow in structure, has a width that is 5.4-5.6% of TL in large males (5.8-6.2% in females). The posterior nasal flaps are broad, with two spiracular folds where the outer fold is slightly taller.

Additional distinguishing features include almost parallel ridges of the rostral cartilage, a subtriangular to sickle-shaped anterior cartilage that is relatively blunt, and a discernible prebranchial sensory pore patch extending to the first gill slit. The postscapular sensory canal is typically notched with visible lateral pores, and there are inconspicuous thorn patches on the supraorbit and scapular region. Denticles are primarily located on the anterior portion of the dorsal fins, with the posterior two-thirds remaining bare. The dorsal fins are relatively tall, with the height of the first being 7.6-9.5% of TL. Notably, the pelvic-fin inner margin is shorter than its base, with an interdorsal distance of 2.1-2.7 times the first dorsal-fin base length.

The coloration of the Whitespotted Guitarfish varies widely, with a dorsal side ranging from plain brownish to greenish-brown, sometimes faintly or strongly marked with small white spots or ocelli, or exhibiting a combination of reticulations and ocelli. The posterior half of the dorsal and caudal fins is usually dusky or blackish, while the snout may display a pale or dusky tip without long teardrop-shaped markings.

The natural habitat of this species includes the 🌊 Western Indian Ocean, specifically the Gulf of Aqaba, Gulf of Suez, the 🌊 Red Sea, and regions extending from Muscat (🇴🇲 Oman) to 🇵🇰 Pakistan.

Why it's threatened

Residential & commercial development

Housing & urban areas

Biological resource use

Intentional use: (subsistence/small scale) [harvest] · Intentional use: (large scale) [harvest] · Unintentional effects: (subsistence/small scale) [harvest] · Unintentional effects: (large scale) [harvest]

The Spotted Guitarfish is taken in a variety of fisheries including demersal trawls, inshore set gillnets and set nets operating that are common throughout its range or through targeted fisheries in the northern Red Sea (Bonfil and Abdallah 2004). There is little information on catches of the Spotted Guitarfish as species-specific data is not always recorded, however, the high level of exploitation on its habitat is of concern. For example, in the Saudi Red Sea, the number of traditional vessels operating increased from about 3,100 to 10,000 between 1988 and 2006 (Bruckner et al. 2011). In Iran, there is increasing fishing effort with the number of fishermen going from 70,729 in 1993 to 109,601 in 2002 (Valinassab et al. 2006). In Pakistan waters, about 2,000 trawlers operate in shelf waters, targeting shrimp in shallow waters and fish in outer shelf waters (M. Khan pers. comm. 06/02/2017). The species is also taken as bycatch off Oman and the UAE but is usually only seen in small numbers at the markets (R.W. Jabado pers. obs.).

Marine habitats in the Gulf are experiencing high levels of disturbance and quickly deteriorating due to major impacts from development activities (including dredging and reclamation), desalination plants, industrial activities, habitat destruction through the removal of shallow productive areas and major shipping lanes (Sheppard et al. 2010) which is likely to impact this species. Little is known of this species’ biology or habitat but, like other guitarfishes this species may be vulnerable due to similar life history characteristics that lead to low productivity. Their young may use coastal nursery grounds that are easily impacted by habitat degradation through pollution and coastal development.

Threat classification from the IUCN Red List.