Morphological Characters of the Thickbody Skate Amblyraja frerichsi (Krefft 1968) (Rajiformes: Rajidae), with Notes on Its Biology

Abstract

Detailed descriptions of morphological features, morphometrics, neurocranium anatomy, clasper structure and egg case descriptions are provided for the thickbody skate Amblyraja frerichsi; a rare, deep-water species from Chile, Argentina and Falkland Islands. The species diagnosis is complemented from new observations and aspects such as colour, size and distribution are described. Geographic and bathymetric distributional ranges are discussed as relevant features of this taxońs biology. Additionally, the conservation status is assessed including bycatch records from Chilean fisheries.

Ontogenetic development of the otic region in the new model organism, Leucoraja erinacea (Chondrichthyes; Rajidae)

“…Anatomical terms of the skull of Leucoraja erincaea follows Bustamate et al . (2012). Measurements of the neurocranium are defined as (Fig.…”

New records and range extension of two deep-sea skate genera, Amblyraja and Notoraja (Elasmobranchii: Rajiformes), in the southeastern Pacific Ocean

“…Furthermore, on a biological note, it is interesting to remark that in the Peruvian specimen (the only juvenile male known), the snout appears relatively shorter than that of the adult male holotype, and is more similar in shape to that of the female specimens depicted in the original description, suggesting secondary sexual dimorphism in the species, as Concha et al (2016) hypothesize. Krefft (1968) described the thick body skate, A. frerichsi, on the basis of 34 specimens (the female holotype and 33 paratypes), collected off Argentina and Uruguay by the R/V Walther Herwig at a depth between 600 and 1000 m. Subsequently, it has been recorded near Rio de Janeiro (Gomes et al, 2019) and probably around the Falkland/Malvinas Islands (Bizikov et al, 2004;Pollom et al, 2021) in the Atlantic Ocean, and along much of the Chilean coast (Bustamante et al, 2012;Ñacari et al, 2019) in the Pacific. The records documented in this study represent a range extension of approximately 530 km (∼5°of latitude) north of its earlier known distribution (bottom right; Figure 3).…”

“…Data taken fromBustamante et al (2012) andKrefft (1968). a For meristics, Krefft analysed 16 individuals.…”

Description and quantitative analysis of the dentition of the southern thorny skate Amblyraja doellojuradoi

“…In the case of A. doellojuradoi the range in the number of rows of teeth (24–37 upper jaw; 24–35 lower jaw) are very different from those that have been observed in other species of this genus: e.g. A. radiata has 36–46 rows (Shark Trust, ); A. frerichsi has 36–42 rows in the upper and 37–40 in the lower jaw (Bustamante et al ., ); A. jenseni has 52–63 in the upper and 54–61 in the lower jaw (Orlov & Cotton, ). This marked difference in the number of tooth rows between A. doellojuradoi and other species of Amblyraja may be due to the maximum size of each species.…”

“…(, , ) conducted a thorough review of the tooth morphology of skates, describing and illustrating the dentition of 26 representative genera worldwide, allowing subsequent comparison with other species and subsequent analysis and interpretation of these variations. Of the 10 species that comprise the genus Amblyraja Malm 1877, only the dentition of the starry skate Amblyraja radiata (Donovan 1808) has been analysed in detail so far and few data on the dentition of the thickbody skate Amblyraja frerichsi (Krefft 1968) and the Jensen's skate Amblyraja jenseni (Bigelow & Schroeder 1950) were published (Orlov & Cotton, ; Bustamante et al ., ). In the south‐west Atlantic Ocean Amblyraja doellojuradoi (Pozzi 1935) is the most common species of its genus, but little is known of its biology so far.…”