Elasmobranchii (sharks and rays) > Rajiformes
(Skates and rays) > Arhynchobatidae
Etymology: Rioraja: Latin, rivus = river (in Greek, rheo) + Latin, raja, -ae = ray, fish.
Environment / Climate / Range
Marine; demersal; depth range ? - 130 m (Ref. 26375). Subtropical
Size / Weight / Age
Maturity: Lm ?  range ? - ? cm
Max length : 33.0 cm WD male/unsexed; (Ref. 26408)
Southwest Atlantic: Espírito Santo, Brazil to Argentina.
A coastal species found on sand, mud or gravel bottoms (Ref. 26375). Feeds on crustaceans, mollusks and fishes (Ref. 26375). Oviparous (Ref. 50449). Eggs have horn-like projections on the shell (Ref. 205).
Life cycle and mating behavior
Maturity | Reproduction | Spawning | Eggs | Fecundity | Larvae
Oviparous, paired eggs are laid. Embryos feed solely on yolk (Ref. 50449).
McEachran, J.D. and K.A. Dunn, 1998. Phylogenetic analysis of skates, a morphologically conservative clade of elasmobranchs (Chondrichthyes: Rajidae). Copeia 1998(2):271-290. (Ref. 27314)
IUCN Red List Status (Ref. 96402)
CITES (Ref. 94142)
Threat to humans
ReferencesAquacultureAquaculture profileStrainsGeneticsAllele frequenciesHeritabilityDiseasesProcessingMass conversion
Estimates of some properties based on models
Phylogenetic diversity index (Ref. 82805
= 1.0000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.00525 (0.00327 - 0.00843), b=3.04 (2.90 - 3.18), based on LWR estimates for species & Subfamily-body shape (Ref. 93245
Trophic Level (Ref. 69278
): 3.6 ±0.0 se; Based on diet studies.
Resilience (Ref. 69278
): Low, minimum population doubling time 4.5 - 14 years (Assuming fecundity<100).
Vulnerability (Ref. 59153
): High vulnerability (64 of 100) .