Psammobatis lentiginosa McEachran, 1983

Santiago, Evelyn F. & Soares, Karla D. A., 2025, Taxonomy and morphology of three species of Psammobatis distributed in the Southwestern Atlantic Ocean (Rajiformes: Arhynchobatidae) with notes on intraspecific variation, Neotropical Ichthyology (e 240074) 23 (2) : -

Psammobatis lentiginosa McEachran, 1983

Psammobatis extenta —Norman, 1937:28 (in part) (Patagonia; catalogue).

Psammobatis lentiginosa McEachran, 1983:62 , fig. 17 (original description; type-locality: off the coast of Uruguay). —Andreata, Séret, 1995:581 ( Espírito Santo, Brazil; listed). —McEachran, Dunn, 1998 (systematic study). —Compagno, 1999:489 (listed). —Mazzoleni, Schwingel, 1999:114 (Itajaí, Santa Catarina, Brazil; listed). —Cousseau et al., 2000:29 ( Argentina and Uruguay; catalogue). —Menni, Stehmann, 2000:87 ( Argentina, Uruguay and Brazil; listed). —Paragó, 2001 (systematic study). — Gomes, 2002 (systematic study). —Gomes, Gadig, 2003:29 ( São Paulo, Brazil; listed). —Mabragaña, 2007 ( Argentina; biological and ecological study). —Cousseau et al., 2007:64 (Mar del Plata, Argentina; catalogue). —Perier et al., 2011 ( Argentina; reproductive biology). —Mabragaña et al. 2012 (reproductive biology). —Weigmann, 2016:100 (listed). —Last et al., 2016:458 (listed). —Nión et al., 2016:23 ( Uruguay; listed). —Gomes et al., 2019:300, fig. 292 ( Rio de Janeiro, Brazil; catalogue). —Brum-Neto, Lucena, 2020 ( Brazil; tooth morphology). —Mabragaña et al., 2020 (systematic study). —Sabadin et al., 2020:1900–1 ( Argentina, Uruguay and Brazil; listed). —Mabragaña, Cousseau, 2021:65 ( Argentina; listed). —Gabbanelli et al., 2022 (systematic and biological study).

Diagnosis. Psammobatis lentiginosa is distinguished from P. extenta and P. rutrum by the dark brown background color with darker spots distributed randomly throughout the dorsal region ( vs. smaller spots in P. extenta and whitish spots in P. rutrum ); thorns on the pectoral fin reduced or absent ( vs. present in P. extenta and P. rutrum ); interruption of only the middorsal thorn row up to the axillary region of pelvic fin ( vs. continuous dorsal thorns rows after the scapular region in P. extenta and interruption of all three rows in P. rutrum ); a rough band of denticles in dorsal central region, contrasting with the smooth aspect of pectoral fins ( vs. absence of contrast in P. extenta and P. rutrum ); thorns reduced or absent in the pectoral posterior region of males ( vs. present in P. extenta and P. rutrum ); females with well-developed prickles on the posterior lobe of the pelvic fins ( vs. dermal denticles poorly developed in P. extenta and P. rutrum ); anterior fontanelle trapezoidal ( vs. rectangular in P. extenta ); basal fenestrae kidney-shaped ( vs. rectangular and narrow in P. extenta ); dorsal terminal cartilage 2 plate-shaped ( vs. triangular in P. rutrum and absent P. extenta ); accessory terminal cartilage 2 projected transversely to lateral ( vs. flattened dorsoventrally in P. rutrum and absent in P. extenta ); accessory terminal cartilage 1 articulated with the ventral marginal cartilage ( vs. continuous in P. extenta ).

External description. Disc 1.6–1.8 times wider than long ( Tab. 3). Heart-shaped disc in juvenile and adult specimens; subtle in the former and accentuated in the latter. Adults with wide pectoral fins and convex margins in the posterior region, while the anterior region narrows towards the snout. Adult males with concave anterior disc margin close to the orbital region; disc width at eye line in females is 1.1 times longer than in males.

Preorbital length 2.9–3.2 times eye horizontal diameter and 3.0–3.3 times interorbital distance. Preoral length 1.4–1.7 times mouth width. Upper jaw arched, especially in middle region; lower jaw convex. First pair of gill openings 1.3–1.5 times larger than fifth. Distance between first gill slits 1.8–2.1 times the distance between fifth.

Pelvic fins convex externally with a notch forming anterior and posterior lobes. Pelvic anterior lobe shorter with convex anterior margin; posterior margin distinguished by radial tips and continuously connected to lateral margin of posterior lobe. Posterior lobe with a convex lateral margin and a straight inner margin. Dorsal fins similar in size and shape, with rounded apex. Distance from the pelvic posterior margin to origin of first dorsal fin 2.7–2.9 times the distance from first dorsal origin to posterior margin of caudal fin. Tail long, 1.7 times in total length and 1.3–1.4 times the snout-vent distance. Caudal fin rounded.

Coloration in alcohol. Dorsal coloration dark brown, covered with darker spots distributed randomly and sometimes forming circles ( Fig. 3C). Whitish spots distributed over the dorsal surface. Preorbital region with a lighter triangular area contrasting to the predominant background color as in P. extenta ( Figs. 3A, C). In juveniles, a dark spot located in the central region of each pectoral fin as in P. rutrum ( Figs. 3E, 5B). Black spot on the snout tip present in some specimens as in P. extenta and P. rutrum ( Figs. 3A, C, E). Tail region similar to that described for the rest of the body. Ventral region predominantly cream ( Fig. 3D).

Dermal denticles. Rostral and malar thorns forming rows with no differences between sexes; star-shaped base and a curved crown that narrows towards its distal end ( Fig. 10E). Rows of alar thorns of adult males situated posterior to the malars and positioned horizontally, close to pectoral lateral margin, with distal end oriented medially; elongated base and a thorn-shaped crown, arranged in one to three alternating rows, with around five to 20 denticles ( Fig. 10A; Tab. 2).

Head with one to four preorbital thorns, none to two midorbital thorns, none to two postorbital thorns, and none to four spiracular thorns. Thorns similar in structure to the nuchal and scapular. Nuchal and scapular thorns fworming a triangular grouping, organized into one to three nuchal thorns and three to 16 scapular thorns; leaf-shaped base with shallow grooves and a curved crown with an extremely sharp distal end ( Fig. 10C).

No mid-pectoral thorns on pectoral fins. Thorns reduced or absent on pectoral fins of adults, giving a smooth appearance. Posterior pectoral thorns present in females and reduced or absent in adults males; cross-shaped or star-shaped base, with a curved crown and tapered distal end ( Figs. 10B, D).

Males with no dermal denticles on their claspers ( Fig. 8B). Adult females with a cluster of prickles located on the posterior lobe of the pelvic fin; cross-shaped base and crown curved with a tapered distal end ( Fig. 10F). Adult males with reduced or absent dermal denticles on this region.

Middorsal row of thorns presenting an interruption that extends to pelvic insertion. Middorsal and dorsolateral thorns similar in structure to nuchal and scapular thorns but relatively smaller. Smaller denticles present posteriorly to scapula and around rows, giving a rough texture to this region ( Fig. 4E). Cross-shaped base and crown curved with a tapered distal end.

One row of mid-caudal thorns and two caudo-lateral thorns, one on each side of the tail, all oriented anterior-posteriorly. Caudo-lateral thorns with base and crown flattened dorsolaterally. Mid-caudal thorns similar in structure to the middorsal thorns and forming a continuous row with them, with around 26 to 54 denticles ( Tab. 2).

Geographical distribution. Examined specimens collected between Rio de Janeiro and Santa Catarina; most of the collection sites are concentrated in Santa Catarina ( Fig. 9). The geographic distribution of P. lentiginosa extends as far as the Gulf of San Jorge, Argentina (Mabragaña, 2007).

Material examined. BMNH 1935.9 . 11.2, holotype. ZMH 25230 [ex ISH 1034– 1966 ], 1 . ZMH 25231 [ex 1501–1966], 1. ZMH 25232 [ex 1622–1966], 1. ZMH 25233 [ex 1676–1966], 1. MZUSP 13089–102 , 14 , paratypes, off the coast of Uruguay, 34°S 50°W. Santa Catarina : MZUSP 42847 , male, 312 mm TL, 166 mm DW, between Rio de Janeiro and Santa Catarina. MZUSP 86551 *, male, 315 mm TL, 171 mm DW, 26°42’7.0”S 46°43’19.0”W . MZUSP 86758 *, female, 226 mm TL, 126 mm DW, between Rio de Janeiro and Santa Catarina. MZUSP 127757 , 4 , 280–406 mm TL, 146–215 mm DW. MZUSP 127758 , 6 , 283–345 mm TL, 153–185 mm DW, Bombinhas . MZUSP 127759 , 8 , 118.4 – 306 mm TL, 61.3–162 mm DW, Bombinhas. Locality undetermined : MNRJ 20608 , 2 , 290–296 mm TL, 150– 150 mm DW.