Interrelationships and Subgeneric Classification of Raja erinacea and R. ocellata Based on Claspers, Neurocrania and Pelvic Girdles (Pisces: Rajidae)

McEachran, John D.; Martin, Chester O.

doi:10.2307/1443685

Cited by 8 publications

(7 citation statements)

References 7 publications

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“…In the case of L. erinacea, the apparent abundance increase since 1970 could be artifactual due to misidentification issues, a hypothesis supported by both (1) the marked increase in mean number of L. erinacea per tow in the late 1970s (mature) and late 1980s (immature) coincident with improved identification techniques (McEachran & Musick, 1973) and (2) the great variability in L. erinacea adult abundance from year to year. Although identification issues are usually most applicable to immature skates <300 mm L T (McEachran & Musick, 1973;Alvarado Bremer et al, 2005), there are also many morphometric similarities between L. ocellata and L. erinacea of larger sizes (McEachran & Martin, 1978), making classification of the smaller L. erinacea potentially difficult for inexperienced observers. Alternately, an increase in L. erinacea abundance on the ESS could be partly due to competitive release, a theory used previously to explain increases in smaller skate species such as R. radiata Donovan in the North Sea (Walker & Heesen, 1996) following the removal of larger skates .…”

Section: Discussionmentioning

confidence: 99%

Reproductive characteristics and population decline of four species of skate (Rajidae) off the eastern coast of Canada

McPhie

Campana

2009

Journal of Fish Biology

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Four of the most common species of skate (Rajidae) were studied off eastern Canada to determine if their reproductive characteristics were linked to their population trajectories. The fecundity of the winter skate Leucoraja ocellata, the little skate Leucoraja erinacea, the thorny skate Amblyraja radiata and the smooth skate Malacoraja senta averaged between 41 and 56 egg cases per year for each species. For all species but L. ocellata, males matured at larger sizes and at later ages than females. Theoretical rates of population increase for non-equilibrium populations of L. ocellata (c. 0.07), M. senta (c. 0.14) and L. erinacea and A. radiata (c. 0.20) were low compared to most fishes, indicating that north-west Atlantic skates are intrinsically unproductive, yet are theoretically capable of supporting low-level fisheries. Nevertheless, the results of 36 years of research surveys indicate that the abundance of mature L. ocellata, A. radiata and M. senta all decreased by >90% since 1970, indicating that past fishing mortality (both directed and undirected) has outstripped the net productivity of the skate populations on the eastern Scotian Shelf. The relationship between maximum age (t(max)) and age of maturity (t(mat)) was a better predictor of population growth rate than was body size, with the species exhibiting the highest ratios of t(mat) :t(max) (L. ocellata = 0.68, M. senta = 0.66) having the lowest predicted population growth rates. L. ocellata appears to have the lowest productivity and has experienced the greatest population decline, thus raising concerns over its future status.

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Section: Discussionmentioning

confidence: 99%

Reproductive characteristics and population decline of four species of skate (Rajidae) off the eastern coast of Canada

McPhie

Campana

2009

Journal of Fish Biology

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“…A component promontory is absent in most taxa examined (68, 0) with the exception of the guitarfishes P. horkelii and Z. brevirostris , and the skates B. nigriventralis , D. clarkii and L. garmani (68, 1; Hulley, 1972; McEachran & Martin, 1978, figures 1–4; McEachran & Compagno, 1982, figures 1–21).…”

Section: Resultsmentioning

confidence: 98%

“…A component roll is present in B. nigriventralis , L. garmani and D. clarkii (67, 1; McEachran & Martin, 1978, figures 1–4; McEachran & Compagno, 1982, figures 1–21). This structure is absent in all other taxa examined (67, 0).…”

Section: Resultsmentioning

confidence: 99%

Phylogeny of the tribe Riorajini with comments on the morphological character evolution within Rajiformes (Chondrichthyes, Batoidea)

2023

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The tribe Riorajini is composed of four species, Rioraja agassizii, Atlantoraja castelnaui, A. cyclophora and A. platana, which are endemic to the inshore waters of the Southwestern Atlantic Ocean. Previous studies have hypothesized the monophyly of this group but interrelationships within its members remain not fully understood. In this study, we analysed quantitative as well as qualitative morphological characters related to external morphology, squamation, neurocranium, visceral arches, pectoral and pelvic girdles and claspers, totalizing 82 characters, representing a greater number than previously used in studies focused on rajiform systematics. 24 terminal taxa were included, and two different analyses were carried out testing Narcine brasiliensis and Pseudobatos horkelii as roots of the cladogram. The monophyly of Riorajini is supported by five quantitative and three discrete characters, including a caudal length smaller than disc length, sensory pores and mucous canals darkly pigmented on ventral surface of disc, and preorbital flange present. Clasper morphology was phylogenetically informative since it contributes to diagnose Rioraja in which an accessory terminal 2 cartilage is absent and to support a sister relationship between A. cyclophora + A. platana. Squamation, teeth and neurocranial morphology need to be thoroughly investigated in order to revise their terminology, propose and test hypotheses of homology and improve our knowledge on morphological variation regarding ontogeny and sexual dimorphism.

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“…Nevertheless, the interpretation of these features is often difficult, even for the experienced taxonomist. Classical pencil drawings have been considered the gold standard for more than 100 years in elasmobranch taxonomy, clearly outperforming photographs or radiographs, e.g., [ 7 , 27 , 30 , 31 , 38 , 41 , 50 , 51 , 55 , 58 , 59 , 60 , 61 , 62 ]. Recently, digital taxonomic drawings have emerged as an alternative, which has been employed to further simplify the features and, thereby, enable easier interpretation of the drawings, e.g., [ 9 , 53 , 54 ].…”

Section: Discussionmentioning

confidence: 99%

Description of a Remarkable New Skate Species of Leucoraja Malm, 1877 (Rajiformes, Rajidae) from the Southwestern Indian Ocean: Introducing 3D Modeling as an Innovative Tool for the Visualization of Clasper Characters

Weigmann,

Stehmann,

Séret

et al. 2024

Biology

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A remarkable new deep-water skate, Leucoraja longirostris n. sp., is described based on eight specimens caught during different expeditions to the southern Madagascar Ridge in the southwestern Indian Ocean. The new species differs from all congeners by its remarkably long and acutely angled snout (horizontal preorbital length 17.2–22.6% TL vs. 8.5–11.9% TL and 4.2–6.1 vs. 1.7–3.5 times orbit length, snout angle 65–85° vs. 90–150°). Furthermore, it is apparently endemic to the Madagascar Ridge, distant from the known distribution areas of all congeners. In addition to L. fullonica and L. pristispina, L. longirostris n. sp. is also the only species with plain dorsal coloration. Furthermore, the new species is the only Leucoraja species with an external clasper component dike and, besides L. wallacei, the only one with four dorsal terminal (dt) cartilages. The shape of the accessory terminal 1 (at1) cartilage with four tips is also unique within the genus. A new approach for the visualization of the clasper characters is introduced based on 3D models of all skeletal and external features. This enables a much easier and much more precise interpretation of every single clasper component, of the entire structure, and, in particular, the relationship between external features and skeletal cartilages. A new English translation of the first diagnosis of Leucoraja is provided, along with a revised generic diagnosis and a key to the species of Leucoraja in the Indian Ocean.

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Interrelationships and Subgeneric Classification of Raja erinacea and R. ocellata Based on Claspers, Neurocrania and Pelvic Girdles (Pisces: Rajidae)

Cited by 8 publications

References 7 publications

Reproductive characteristics and population decline of four species of skate (Rajidae) off the eastern coast of Canada

Reproductive characteristics and population decline of four species of skate (Rajidae) off the eastern coast of Canada

Phylogeny of the tribe Riorajini with comments on the morphological character evolution within Rajiformes (Chondrichthyes, Batoidea)

Description of a Remarkable New Skate Species of Leucoraja Malm, 1877 (Rajiformes, Rajidae) from the Southwestern Indian Ocean: Introducing 3D Modeling as an Innovative Tool for the Visualization of Clasper Characters

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