Riorajaagassizii pertence ao gênero monotípico Rioraja e difere das demais espécies da tribo Riorajini classificadas no gênero Atlantoraja pelo formato da aba nasal anterior, escamas, esqueleto do clásper, medidas corpóreas e padrão de coloração. Embora R. agassizii seja uma espécie bem conhecida, comumente capturada em águas costeiras do Atlântico Sul Ocidental, sua morfologia externa e anatomia interna não foram totalmente descritas e pouco se sabe sobre a variação intraespecífica nesta espécie. Espécimes juvenis, adultos, machos e fêmeas foram examinados, medidos e dissecados. Neste estudo, a espécie é redescrita e descrições detalhadas e ilustrações da morfologia externa, neurocrânio, maxilas, arcos hioide e branquiais, nadadeira e cintura pélvicas são apresentadas. Adicionalmente, notas sobre dimorfismo sexual e variação ontogenética na coloração, medidas corpóreas e craniais, e dentículos dérmicos são fornecidas.

Palavras-chave:
Anatomia; Dimorfismo sexual; Taxonomia

Autoria

Karla D. A. Soares

Laboratório de Ictiologia, Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, Trav. 14, 101, 05508-900 São Paulo, SP, Brazil. (KDAS) karlad.soares@yahoo.com.br (corresponding author); (RAM) moreirarandrade@gmail.com.Universidade de São PauloBrazilSão Paulo, SP, BrazilLaboratório de Ictiologia, Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, Trav. 14, 101, 05508-900 São Paulo, SP, Brazil. (KDAS) karlad.soares@yahoo.com.br (corresponding author); (RAM) moreirarandrade@gmail.com.

https://orcid.org/0000-0002-8984-495X

Renan A. Moreira

https://orcid.org/0000-0002-9908-6259

Ulisses L. Gomes

Laboratório de Taxonomia de Elasmobrânquios, Departamento de Zoologia, Instituto de Biologia, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, Maracanã, 20550-900 Rio de Janeiro, RJ, Brazil. (ULG) ulisseslg@netscape.net.Universidade do Estado do Rio de JaneiroBrazilRio de Janeiro, RJ, BrazilLaboratório de Taxonomia de Elasmobrânquios, Departamento de Zoologia, Instituto de Biologia, Universidade do Estado do Rio de Janeiro, Rua São Francisco Xavier, 524, Maracanã, 20550-900 Rio de Janeiro, RJ, Brazil. (ULG) ulisseslg@netscape.net.

https://orcid.org/0000-0002-7088-4134

Edited-by

Lisa Whitenack

Correspondence

Karla D. A. Soares karlad.soares@yahoo.com.br

Author's Contribution

Karla D. A. Soares: Data curation, Formal analysis, Investigation, Methodology, Project administration, Visualization, Writing-original draft, Writing-review and editing.

Renan A. Moreira: Data curation, Formal analysis, Writing-original draft, Writing-review and editing.

Ulisses L. Gomes: Conceptualization, Data curation, Formal analysis, Funding acquisition,

Investigation, Methodology, Project administration, Writing-original draft, Writing-review and editing.

Competing Interests

The authors declare no competing interests.

Ethical Statement

Not applicable.

SCIMAGO INSTITUTIONS RANKINGS

Figuras | Tabelas

Figuras (9)
Tabelas (3)

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FIGURE 1 |
Terminology of thorns. alt, alar; idt, interdorsal; iot, interorbital; ist, interespiracular; mct, mediocaudal; mdt, middorsal; mot, midorbital; nut, nuchal; pet, preorbital; pot, postorbital; rst, rostral; sct, scapular; spt, spiracular.

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FIGURE 2 |
A. Drawing of Rioraja agassizii provided by Müller, Henle, (1841)Müller J, Henle FGJ. Systematische Beschreibung der Plagiostomen. Berlin: Veit; 1841. Available from: https://www.biodiversitylibrary.org/item/30065#page/5/mode/1up
https://www.biodiversitylibrary.org/item... . B. Dorsal view of MNHN 2430, male, 405 mm TL (lectotype designated herein and modified from MNHN database). Scale bar = 20 mm.

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FIGURE 3 |
External morphology and color pattern of Rioraja agassizii. A. dorsal view and B. ventral view of MZUSP (uncatalogued), 424 mm TL; C. dorsal view and D. ventral view of UERJ 1569, female, 466 mm TL; E. MZUSP 117280, female, 543 mm TL; F. MNRJ 50512, female, 505 mm TL. Scale bars = 10 cm.

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FIGURE 4 |
Ventral view of the head of Rioraja agassizii. A. MZUSP 117280, female, 543 mm TL. B. USP (uncatalogued), male. Scale bars = 20 mm.

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FIGURE 5 |
Neurocranium of Rioraja agassizii, MZUSP 117280, female, 543 mm TL. A. dorsal, B. ventral views. af, anterior fontanelle; bp, basal plate; epb, epiphysial bridge; end, endolymphatic foramen; icf, internal carotid artery foramen; inc, inner nasal cartilage; ins, internasal space; ja, jugal arch; na, nasal aperture; nc, nasal capsule; oc, otic capsule; occ, occipital condyle; onc, outer nasal cartilage; opf, ophthalmic foramen; peri, perilymphatic foramen; pf, posterior fontanelle; pnc, posterior nasal cartilage; pos, postorbital process; pre, preorbital process; ptp, pterotic process; ra, rostral appendix; rb, rostral base; rn, rostral node; rs, rostrum. Scale bar = 10 mm.

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FIGURE 6 |
Neurocranium of Rioraja agassizii, MNRJ 50512, female, 505 mm TL. A. dorsal, B. ventral, C. lateral views. II, foramen for the optic nerve; III, foramen for the oculomotor nerve; IV, foramen for the trochlear nerve; VI, foramen for the abducens nerve; acvf, anterior canal vein foramen; af, anterior fontanelle; antf, antorbital facet; apba, foramen for the afferent pseudobranchial artery bp, basal plate; epb, epiphysial bridge; end, endolymphatic foramen; ethn, foramen for the passage of the ethmoidal nerve; fm, foramen magnum; hf, hyomandibular facet; hVII, foramen for the passage of the hyomandibular ramus of the facialis nerve; icf, internal carotid artery foramen; inc, inner nasal cartilage; ins, internasal space; ja, jugal arch; na, nasal aperture; nc, nasal capsule; oc, otic capsule; occ, occipital condyle; onc, outer nasal cartilage; opc, opistotic crest; opd, optic pedicel; opf, ophthalmic foramen; ornc oronasal canal; peri, perilymphatic foramen; pf, posterior fontanelle; pfc, prefacial commissure; pnc, posterior nasal cartilage; pos, postorbital process; pre, preorbital process; prf, parietal fossa; prof, prootic formamen; ptp, pterotic process; ra, rostral appendix; rb, rostral base; rn, rostral node; rs, rostrum; soc, supraorbital crest; sopf, superficial ophtalmic foramen.

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FIGURE 7 |
Visceral arches of Rioraja agassizii, MNRJ 50512, female, 505 mm TL. A. jaws; B, D. dorsal and C, E. ventral views of hyoid and gill arches. abc, anterior portion of basibranchial copula; bbc, basibranchial copula; bh, basihyal; cb 1–5, ceratobranchials I–V; mck, Meckel’s cartilage; cph, cerato-pseudohyoid; eb 1–5, epibranchials I–V; eph, epi-pseudohyoid; hb 2–4, hypobranchials II–IV; lpbh, lateral projection of basihyal; pb 1–5, pharyngobranchials I–V; pq, palatoquadrate. Scale bar = 5 mm.

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FIGURE 8 |
Pelvic girdle and fin skeleton of Rioraja agassizii, MNRJ 50512, female, 505 mm TL. 1pvr, first pelvic radial segment; 1pvrc, condyle for the first pelvic radial segment; bpt, basipterygium; lpp, lateral pelvic process; obf, obturator foramen; pib, pubischiadic bar; pvr, pelvic radial segments. Scale bar = 10 mm.

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FIGURE 9 |
Map showing the geographic distribution of Rioraja agassizii based on material examined in this study (red) and literature (blue).

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TABLE 1 |
Body measurements of males and females of Rioraja agassizii. Total length (TL) in millimeters and other measurements as percentages of total length (% TL).

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TABLE 2 |
Meristic counts of males and females, juveniles and adult specimens of Rioraja agassizii.

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TABLE 3 |
Neurocranial measurements as percentages of neurocranium total length (% NTL).

FIGURE 1 | Terminology of thorns. alt, alar; idt, interdorsal; iot, interorbital; ist, interespiracular; mct, mediocaudal; mdt, middorsal; mot, midorbital; nut, nuchal; pet, preorbital; pot, postorbital; rst, rostral; sct, scapular; spt, spiracular.

FIGURE 2 | A. Drawing of Rioraja agassizii provided by Müller, Henle, (1841)Müller J, Henle FGJ. Systematische Beschreibung der Plagiostomen. Berlin: Veit; 1841. Available from: https://www.biodiversitylibrary.org/item/30065#page/5/mode/1up
https://www.biodiversitylibrary.org/item... . B. Dorsal view of MNHN 2430, male, 405 mm TL (lectotype designated herein and modified from MNHN database). Scale bar = 20 mm.

FIGURE 3 | External morphology and color pattern of Rioraja agassizii. A. dorsal view and B. ventral view of MZUSP (uncatalogued), 424 mm TL; C. dorsal view and D. ventral view of UERJ 1569, female, 466 mm TL; E. MZUSP 117280, female, 543 mm TL; F. MNRJ 50512, female, 505 mm TL. Scale bars = 10 cm.

FIGURE 4 | Ventral view of the head of Rioraja agassizii. A. MZUSP 117280, female, 543 mm TL. B. USP (uncatalogued), male. Scale bars = 20 mm.

FIGURE 5 | Neurocranium of Rioraja agassizii, MZUSP 117280, female, 543 mm TL. A. dorsal, B. ventral views. af, anterior fontanelle; bp, basal plate; epb, epiphysial bridge; end, endolymphatic foramen; icf, internal carotid artery foramen; inc, inner nasal cartilage; ins, internasal space; ja, jugal arch; na, nasal aperture; nc, nasal capsule; oc, otic capsule; occ, occipital condyle; onc, outer nasal cartilage; opf, ophthalmic foramen; peri, perilymphatic foramen; pf, posterior fontanelle; pnc, posterior nasal cartilage; pos, postorbital process; pre, preorbital process; ptp, pterotic process; ra, rostral appendix; rb, rostral base; rn, rostral node; rs, rostrum. Scale bar = 10 mm.

FIGURE 6 | Neurocranium of Rioraja agassizii, MNRJ 50512, female, 505 mm TL. A. dorsal, B. ventral, C. lateral views. II, foramen for the optic nerve; III, foramen for the oculomotor nerve; IV, foramen for the trochlear nerve; VI, foramen for the abducens nerve; acvf, anterior canal vein foramen; af, anterior fontanelle; antf, antorbital facet; apba, foramen for the afferent pseudobranchial artery bp, basal plate; epb, epiphysial bridge; end, endolymphatic foramen; ethn, foramen for the passage of the ethmoidal nerve; fm, foramen magnum; hf, hyomandibular facet; hVII, foramen for the passage of the hyomandibular ramus of the facialis nerve; icf, internal carotid artery foramen; inc, inner nasal cartilage; ins, internasal space; ja, jugal arch; na, nasal aperture; nc, nasal capsule; oc, otic capsule; occ, occipital condyle; onc, outer nasal cartilage; opc, opistotic crest; opd, optic pedicel; opf, ophthalmic foramen; ornc oronasal canal; peri, perilymphatic foramen; pf, posterior fontanelle; pfc, prefacial commissure; pnc, posterior nasal cartilage; pos, postorbital process; pre, preorbital process; prf, parietal fossa; prof, prootic formamen; ptp, pterotic process; ra, rostral appendix; rb, rostral base; rn, rostral node; rs, rostrum; soc, supraorbital crest; sopf, superficial ophtalmic foramen.

FIGURE 7 | Visceral arches of Rioraja agassizii, MNRJ 50512, female, 505 mm TL. A. jaws; B, D. dorsal and C, E. ventral views of hyoid and gill arches. abc, anterior portion of basibranchial copula; bbc, basibranchial copula; bh, basihyal; cb 1–5, ceratobranchials I–V; mck, Meckel’s cartilage; cph, cerato-pseudohyoid; eb 1–5, epibranchials I–V; eph, epi-pseudohyoid; hb 2–4, hypobranchials II–IV; lpbh, lateral projection of basihyal; pb 1–5, pharyngobranchials I–V; pq, palatoquadrate. Scale bar = 5 mm.

FIGURE 8 | Pelvic girdle and fin skeleton of Rioraja agassizii, MNRJ 50512, female, 505 mm TL. 1pvr, first pelvic radial segment; 1pvrc, condyle for the first pelvic radial segment; bpt, basipterygium; lpp, lateral pelvic process; obf, obturator foramen; pib, pubischiadic bar; pvr, pelvic radial segments. Scale bar = 10 mm.

FIGURE 9 | Map showing the geographic distribution of Rioraja agassizii based on material examined in this study (red) and literature (blue).

TABLE 1 | Body measurements of males and females of Rioraja agassizii. Total length (TL) in millimeters and other measurements as percentages of total length (% TL).

Measurement s	Males (n = 13)		Females (n = 25)
Measurement s	Range	Mean	Range	Mean
Total length (mm)	355–470	418.0	364–561	471.0
Disc width	58.0–68.0	64.3	55.9–70.3	62.9
Disc length	48.0–55.7	51.2	44.2–60.4	55.6
Prenasal length	8.0–11.4	9.7	9.2–13.8	10.9
Preoral length	10.7–13.7	12.9	11.6–15.7	13.5
Preorbital length	12.6–15.1	12.7	12.8–15.2	13.7
Eye length	2.4–4.8	3.3	1.8–3.2	2.5
Interorbital distance	4.5–6.4	5.9	4.6–7.7	6.0
Eye-spiracle distance	0.6–0.9	0.7	0.5–0.9	0.7
Spiracle diameter	2.3–2.8	2.5	1.8–3.0	2.7
Interespiracular distance	5.1–6.0	5.6	5.4–6.2	5.8
Anterior nasal flap length	3.1–3.6	3.4	2.6–4.3	3.5
Internarial distance	4.5–7.1	6.0	5.4–7.8	6.5
Mouth width	5.5–7.6	6.2	5.8–8.4	7.2
First gill width	1.2–1.8	1.2	1.4–2.3	1.7
Third gill width	1.2–1.9	1.4	1.1–2.8	1.9
Fifth gill width	0.8–1.3	1.1	0.9–1.2	1.0
Distance between first gill openings	11.6–13.1	11.9	12.1–14.6	12.5
Distance between fifth gill openings	5.4–6.0	5.7	6.4–8.3	6.6
Pelvic anterior lobe length	10.2–11.6	10.9	9.1–12.3	10.9
Pelvic posterior lobe length	9.5–16.0	12.8	10.2–12.7	11.8
Clasper outer length	12.7–15.2	14.1	–	–
Clasper inner length	20.7–23.2	21.5	–	–
Clasper base length	2.5–3.3	2.8	–	–
Tail width at axil of pelvics	3.7–4.0	3.8	2.9–4.1	3.4
Snout-cloaca length	43.9–48.2	46.1	41.2–50.4	45.5
Cloaca-caudal length	51.5–54.0	52.3	47.8–54.1	51.0
Distance between pelvic and first dorsal fins	24.5–29.6	26.2	22.1–27.5	24.9
Distance between first dorsal and caudal fins	19.6–25.2	23.1	15.9–24.3	22.6
Interdorsal distance	3.9–6.8	5.4	3.0–4.3	3.5
First dorsal fin base	3.2–3.9	3.6	3.2–4.0	3.5
First dorsal fin height	2.3–3.0	2.5	2.2–2.8	2.4
Second dorsal fin base	3.2–4.2	3.5	2.5–4.4	3.9
Second dorsal fin height	2.0–2.5	2.2	1.8–2.4	2.2

TABLE 2 | Meristic counts of males and females, juveniles and adult specimens of Rioraja agassizii.

Counts	Males		Females
Counts	Juveniles	Adults	Juveniles	Adults
Mediocaudal thorns	7–10	10–27	8–13	23–31
Interdorsal thorns	1–4	1	1–4	1–4
Rostral thorns	–	–	–	1–3
Postorbital thorns	–	–	–	1–2
Spiracular thorns	–	–	–	1–2
Interspiracular thorns	–	–	–	1
Nuchal thorns	–	–	–	4–5
Scapular thorns	–	–	–	2–3
Alar thorns	–	72–76	–	–
Upper tooth counts	–	40–45	–	39–51
Lower tooth counts	–	37–42	–	36–48

TABLE 3 | Neurocranial measurements as percentages of neurocranium total length (% NTL).

Counts	Males		Females
Counts	Juveniles	Adults	Juveniles	Adults
Mediocaudal thorns	7–10	10–27	8–13	23–31
Interdorsal thorns	1–4	1	1–4	1–4
Rostral thorns	–	–	–	1–3
Postorbital thorns	–	–	–	1–2
Spiracular thorns	–	–	–	1–2
Interspiracular thorns	–	–	–	1
Nuchal thorns	–	–	–	4–5
Scapular thorns	–	–	–	2–3
Alar thorns	–	72–76	–	–
Upper tooth counts	–	40–45	–	39–51
Lower tooth counts	–	37–42	–	36–48

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E-mail: neoichth@nupelia.uem.br

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[1] Edited-by

Lisa Whitenack