Glaucostegus cemiculus

Glaucostegus cemiculus

  • Common name : Blackchin Guitarfish, Giant guitarfish
  • Order: Rhinopristiformes
  • Family: Glaucostegidae 
  • Synonyms: Rhinobatos cemiculus, Glaucostegus petiti
  • Misidentifications: None.
  • photo credit: Movses

Short description

Large to very large species with an elongated tubular body. Head, body and pectoral fins are combined in a triangular disc, with rostral ridges narrowly separated posteriorly and almost joined anteriorly. Small denticles cover a rough skin. Distance between dorsal fins is about equal to that between the base of the first dorsal fin and the axilla of the pectoral fin. A row of thorns from nape to the first dorsal fin. Thorns along the rostral cartilage, around orbits and spiracles, between dorsal fins.

Color: Beige to brownish dorsal surface. White ventral surface.


  • Total length (TL): 180 cm (max 265 cm).
  • Weight: up to 49.9 kg

Swimming pattern: Axial-undulatory locomotion.

Biology / Ecology

Feeds mainly on benthic crustaceans and small fishes.

Reproduction: Viviparous (aplacental viviparity with histotrophy). Annual reproduction cycle. Size at maturity in Mediterranean (TL): 110-138 cm female, 100-112 cm male. Size at maturity in Senegal (TL): 163 cm female at 5.1 years, 155 cm male at 3.9 years. Mature at smaller size in the Mediterranean Sea: males 100-110 cm TL, females ~110 cm TL. Juveniles per litter per year: 1-6. Size at birth (TL): ~34 cm.

Habitat:  Benthic species living on sandy and muddy bottoms from nearshore to 100 m of depth on the continental shelf.

Generally ambush crustaceans and small fish by pinning them down with their long snouts and then sucking them into their mouths.

Distinguishing characteristics

  • Rostral ridges narrowly separated.
  • Distances between dorsal fins are about equal to that between the base of the first dorsal fin and the axilla of the pectoral fin.

Glaucostegidae: Snout elongated and pointed. Strongly depressed trunk. Pectoral fins enlarged.


Worldwide: Atlantic, from Northern Portugal to Angola.

Mediterranean: Southern and eastern Mediterranean basin. A laying area has been identified from the Gulf of Gabès. One recent record from the Black Sea.

  • Occurence: Abundant.
  • Latest records:  Alexandria – Egypt (2018-2020), Cyprus (2019), Tunisia (2007-2008, 2016-2017), Lebanon (2012-2014), Izmir bay – Turkey (2013), Syria (2003), Iskenderun bay – Turkey (2010-2011), Black Sea (2009-2018), Adriatic Sea (before 1948), Ligurian Sea and upper Tyrrhenian Sea (before 1898).

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Threats: High fishing pressure from West Africa. Taken as bycatch by bottom trawlers with commercial value in some ports of the Mediterranean Sea.

Protection level:

  • Global: Critically Endangered (IUCN 2019, last assessment: 2018)

Key references

  • Carpentieri P., Nastasi A., Sessa M., Srour A. 2021. Incidental catch of vulnerable species in Mediterranean andBblack Sea fisheries – A review. General Fisheries Commission for the Mediterranean – Studies and Reviews 101: I-317.
  • Giovos I., Serena F., Katsada D., Anastasiadis A., Barash A., Charilaou C., Hall-Spencer J.M.,Crocetta F.,Kaminas A., Kletou D, Maximiadi M., Minasidis V., Moutopoulos D.K., Aga-Spyridopoulou R.N., Thasitis I., Kleitou P. 2021. Integrating literature, biodiversity databases, and citizen-science to reconstruct the checklist of Chondrichthyans in Cyprus (Eastern Mediterranean Sea). Fishes 6(3): 24.
  • Golani D. 2005. Checklist of the Mediterranean fishes of Israel. Zootaxa 947(1): 1-90.
  • Lteif M., Mouawad R., Jemaa S., Khalaf G., Lenfant P., Verdoit-Jarraya M. 2016. The length-weight relationships of three sharks and five batoids in the Lebanese marine waters, eastern Mediterranean. Egypt. J. Aquat. Res. 42: 475–477.