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🌊 Marine Critically Endangered 🌡️ Tropical

Widenose guitarfish

Glaucostegus obtusus Müller & Henle, 1841
Max Length
93 cm
Max Weight
-
Lifespan
-
Trophic Level
3.5
Depth
-
Climate
Tropical
Resilience
Low
Vulnerability
34.00/100
Typical Length
-
Depth Zone
demersal

📖 Overview

Found inshore and offshore . Ovoviviparous . Biology little known ; but males are known to be mature ca. 48 cm TL . Probably utilized where it occurs, but details lacking .

Scientific Name
Glaucostegus obtusus
Authority
Müller & Henle, 1841
Habitat
Marine
Climate
Tropical
Body Shape
Elongated
IUCN Status
CR
Max Length
93 cm
Trophic Level
3.5
Resilience
Low
Vulnerability
34.00/100
Salinity
30–40 ppt

🐟 Physical Description

This species is distinguished by the following: colour uniform greyish to brownish body and shovel-shaped disc; short snout broadly triangular, broad oblique nostrils with an oval anterior opening; disc flattened centrally, its length ca 1.2 times its width, anterior margin largely convex, outer corner broadly rounded to abruptly angular; snout relatively obtuse, ca. 80° angle, tip broadly rounded and not extended forward as a lobe, very small orbit its length ca 6.5 time preorbital length, 2.5-2.7 in interorbital space; rostral ridges are well separated, margin of cranium sharply demarcated before eyes; one small spiracular fold; nostrils much shorter than mouth, subequal to internasal width, ca. 50-52 nasal lamellae; anterior nasal flaps barely penetrating into internasal space, the interspace equal to 2.4-2.5 times length of posterior nasal aperture; rough skin covered with small denticles, enlarged slightly and more granular on dorsal surface than ventrally; along midline of the body in young are thorns in irregular row, irregular in shape, often obscure in adults; no obvious patch on each shoulder or greatly enlarged thorns in snout tip and around orbits; long tail, 1.4-1.6 times disc length; short dorsal fins, apices rounded, close together, interspace exceeding twice base length of first dorsal fin, well separated from pelvic fins .: elongated; Cross section: flattened.

🌀 Behaviour

Behavioural data for Widenose guitarfish is currently being reviewed.

🦐 Diet

aquatic invertebrates
small fish
algae
detritus

🥚 Reproduction

🐣 Oviparous 📦 Batch Spawner
Spawning Season
spring-summer
Spawn Location
Pelagic
Fertilization
External

Exhibit ovoviparity (aplacental viviparity), with embryos feeding initially on yolk, then receiving additional nourishment from the mother by indirect absorption of uterine fluid enriched with mucus, fat or protein through specialised structures .

🌍 Habitat & Distribution

Marine; demersal; depth range ? - 60 m . Tropical; 25°N - 0°N, 61°E - 105°E South African records refer to Rhinobatos blochii and Rhinobatos leucospilus (Compagno pers.

🌿 Ecology

Zone Preferences
🌊 Marine ⬇️ Benthic
Trophic Level
3.5±0.5

📐 Morphometrics

Length–Weight Relationship: W = 0.00347 × L3.1 (TL)
Max TL
93cm

🌡️ Water Parameters & Tolerance

Salinity Range
30–40ppt

🛡️ Conservation Assessment

IUCN Category
Critically Endangered
Assessment Date
2018

📊 Population Risk & Fisheries

Population Resilience
Low
Minimum doubling time
Fishing Vulnerability
34.00/100
Low vulnerability
Trophic Level
3.5
Predator
Body Shape
Elongated
Climate Zone
Tropical
Described By
Müller & Henle, 1841

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