Paratrygon parvaspina, Loboda & Lasso & Rosa & Carvalho, 2021

Loboda, Thiago Silva, Lasso, Carlos A., Rosa, Ricardo de Souza & Carvalho, Marcelo Rodrigues de, 2021, Two new species of freshwater stingrays of the genus Paratrygon (Chondrichthyes: Potamotrygonidae) from the Orinoco basin, with comments on the taxonomy of Paratrygon aiereba, Neotropical Ichthyology (e 200083) 19 (2), pp. 1-80 : 25-39

Paratrygon parvaspina , new species urn:lsid:zoobank.org:act:5EF6A291-D95A-4E29-AD87-EDF4BFF635F8

( Figs. 19‒31 , Tabs. 3‒4)

Paratrygon aiereba . —Maldonado-Ocampo et al., 2006:117 [occurrence in the Tomo River, specimen IAvH-P 4684]. —Mejía-Falla et al., 2007:125 [checklist of the species of sharks, rays and skates of Colombia, specimen IAvH-P 4684]. —Maldonado-Ocampo et al., 2008:150 [checklist of the freshwater fishes of Colombia]. —Lasso, Sánchez-Duarte, 2012:134 [citation of specimen IAvH-P 4684].

Paratrygon sp. 2 : —Loboda, 2016: vol.1. vii-ix, 33, 60, 75‒76, 87, 97, 100, 112‒123, 126‒127, 142, 156, 190‒192, 237‒241, vol.2. xvi-xvii, 91‒103, fig. 127, p. 91, fig. 128, p. 92, figs. 129‒130, p. 93, figs. 131‒132, p. 94, figs. 133‒134, p. 95, fig. 135, p. 96, fig. 136, p. 97, fig. 137, p. 98, fig. 138, p. 99, figs. 139‒140, p. 100, figs. 141‒142, p. 101, figs. 143‒144, p. 102, fig. 145, p. 103 [morphometry, morphological description, taxonomic revision, diagnosis, previous misidentifications, distribution].

Holotype. IAvH-P 12447, female, 450 mm DW, Colombia, State of Vichada, Municipality of Puerto Carreño, río Bita , 06°06’07.2’’N 67°29’11.9’’W, 2 Feb 2014, C. Lasso & M. A. Morales-Betancourt.

Paratypes. (3 specimens). IAvH-P 12441, female, 225 mm DW, Colombia, State of Vichada, Locality of PNN El Tuparro, río Tomo, 05°21’09.8’’N 67°55’04.4’’W, 3 Mar 2014, C. Lasso & M. A. Morales-Betancourt. IAvH-P 12446, male, 212 mm DW, same data as previous specimen. MZUSP 117836 , female, 266 mm DW, Venezuela, State of Amazonas, Municipality of Puerto Ayacucho , río Orinoco , 23 Jan 2013, F. Marques .

Non-type. IAvH-P 4684, female, 345 mm DW, Colombia, State of Vichada, Municipality of Cumaribo, Caño Peinilla , tributary of río Tomo , 05°35’08.3’’N 68°0.3’44’’W, 1 Feb, J. Maldonado-Ocampo .

Diagnosis. A species of Paratrygon diagnosed by the following combination of characters. Spiracular process extremely short and reduced, slightly more developed in adults, and with few dermal denticles (vs. P. aiereba with large and knob shaped spiracular processes that almost cover the spiracle aperture, and P. orinocensis with short and straight spiracular process with developed dermal denticles). Caudal sting very reduced, with mean of its length 6.2% DW [5.6‒7.1% DW] (vs. longer caudal stings in P. aiereba and P. orinocensis with means and ranges, respectively, 11.3% DW [3‒17.9% DW], and 11.9% DW [6.7‒15.3% DW]). Tail short, with means of the pre-caudal sting region and the distance between cloaca and tail tip, respectively, 21.1% and 50.4% DW (vs. longer tails in P. aiereba and P. orinocensis , with means of the pre-caudal sting region and the distance between cloaca and tail tip, respectively, 23.5% and 87.8% DW in P. aiereba , and 25.2% and 115.4% DW in P. orinocensis ). Anterior disc margin broadly rounded (vs. P. aiereba and P. orinocensis with well developed and visible concave anterior disc margins, especially the latter). Spiracles small and quadrangular, with mean length 5.2% DW [4.9‒5.8% DW] (vs. larger spiracles in P. aiereba , with mean length 6% DW [4.4‒11.6% DW], and P. orinocensis with triangular and slightly smaller spiracles, with mean spiracle length 5.6% DW [4.5‒7.9% DW]). Rostral projection relatively large (vs. small or minute in P. aiereba and P. orinocensis , respectively). Preorbital processes more laterally projected, externally exceeding level of nasal capsules (vs. preorbital processes less laterally projected, not exceeding level of nasal capsules in P. aiereba and P. orinocensis ). Lateral stay of synarcual cartilage long, exceeding the lateral level of anterior ventral condyle (vs. short in P. aiereba and P. orinocensis not exceeding the lateral level of anterior ventral condyle). Dorsolateral crest of scapular process not pronounced and not exceeding laterally the level of mesocondyle (vs. pronounced dorsolateral crests that laterally exceed the level of mesocondyle in P. aiereba and P. orinocensis ). Propterygium robust (vs. more slender in P. aiereba and P. orinocensis ). Concavity of the internal face of mesopterygium not so pronounced and curved (vs. very pronounced and curved in P. aiereba and P. orinocensis ). Metapterygium robust and highly curved (vs. metapterygium slender and more straight in P. aiereba and P. orinocensis ).

Description. For the general apperance of Paratrygon parvaspina , see Figs. 19‒20 , for morphological characters examined see Figs. 21‒31 . Measurements and counts are showed in Tabs. 3‒4, respectively, and S3.

Paratrygon parvaspina presents a more rounded than oval disc format, with mean of disc length in 106.5% DW [104.9‒110.4% DW]. Anterior margin of disc with an extremely reduced and discrete concavity in its medial portion ( Figs. 19 , 20 ). Disc briefly longer than P. orinocensis , distance from anterior margin of disc to cloaca with mean in 90.3% DW [87.6‒98.6% DW].

Head with greater interorbital distance than P. orinocensis , with mean in 11.6% DW [10.5‒12.2% DW; interspiracular distance short, with mean 15.5% DW and [15‒16.2% DW] ( Tab. 3). Eyes moderately large (mean 2.2% DW) and little pedunculated ( Figs. 4 D-F, 21). Spiracles quadrangular, small, being narrow and slightly larger than eyes, with mean of its lenght 5.2% DW [4.9‒5.8% DW] ( Fig. 21 ). Spiracular process extremely short, underdeveloped, with few dermal denticles, being in juvenile specimens pratically inconspicous; however, some slight development occurs according to the maturity of specimens ( Fig. 21 ). Paratrygon parvaspina with preorbital, prenasal and preoral distances greater than P. orinocensis (means respectively 32.2, 31.5 and 35% DW), being its head slighltly farther from anterior margin of disc than that species. Mean internasal distance 8.1% DW, and mean mouth width 9.8% DW. Teeth triangular, cuspidate, arranged in quincunx in both jaws, and without size difference between teeth from lateral and central rows; teeth of central rows with more developed cusps than laterals, however cusps more similar in height with P. aiereba ’s teeth and minor than P. orinocensis ones. Tooth rows of holotype (IAvH-P 12447, adult female) 31/22 ( Tab. 4).

Branchial basket broad laterally, with mean of distance between first pair of gill slits (anterior part) 20.5% DW, and mean of distance between fifth pair of gill slits (posterior part) 17.6% DW; branchial basket also short, with mean of distance between first and fifth pair of gill slits 10.4% DW ( Tab. 3). Pelvic fin triangular and dorsally covered by disc ( Figs. 20B,D , 21B,D ) its mean anterior margin length 16.6% DW; distances between distal portions of pelvic fins, and between axils of pectoral and pelvic fins respectively 42.5 and 4.1% DW ( Tab. 3). Single male specimen of P. parvaspina examined, IAvH-P 12446 (juvenile specimen) with external and internal clasper lengths respectively 2.8 and 6.6% DW ( Tab. 3).

Tail reduced compared to P. orinocensis and P. aiereba , with narrow base, and short pre-caudal sting portion; post-caudal sting portion prolonged and filiform. Mean distance between cloaca and caudal sting insertion 21.1% DW; mean tail width 6.6% DW ( Tab. 3). Distance from cloaca to tail’s tip measured in all specimens, show a proportional decrease from juveniles to adult specimen (holotype IAvH-P 12447): with range in juveniles from 40.3 to 82.5% DW, whereas adult possess 25.1% DW (S3). Lateral tail folds slightly developed, from tail’s base to caudal sting insertion; dorsal and ventral folds also present and poorly developed, more easily recognizable in region immediately after caudal sting, with dorsal fold more evident. Some specimens with medial ventral groove in tail more developed than others, occurring from tail base to origin of ventral fold.

Squamation. Dermal denticles scattered throughout the dorsal disc and tail ( Fig.

22A). Dermal denticles in central region of disc bigger, more concentrated and visible than denticles on disc margins. Posterior margins of disc with notable concentration of developed thorns with large basal plate (bp) ( Figs. 22B‒C ); some of these thorns may exceed

10 mm in diameter and five mm in height, and possess some minute dermal denticles in its

bp. On the tail, dermal denticles occur only in pre-caudal sting portion. Dermal denticles in central disc generally with 0.5 mm in diameter, presenting a high and narrow crown

( Fig. 23 ). Central coronal plate (ccp) well developed, high and with pointed format; lateral coronal ridges (lcr) small, pointed and generally in number from two to five ( Fig. 23D ).

Female adult specimen (holotype IAvH-P 12447) with just one dorsal and one lateral rows of thorns on tail ( Figs. 24A‒B ). Thorns developed, high and with a broad tubercular base throughout all extension of dorsal row, which originates at tail base and reaches caudal sting insertion. Lateral rows begin just before medial portion of tail and reach caudal sting insertion level; thorns of lateral rows very similar to dorsal ones, also well developed, high and with a broad tubercular base ( Figs. 24A‒C ). Juveniles with just the dorsal row developed, only in pre-caudal sting portion; thorns developed but smaller than in adults, also with tubercular base ( Figs. 24D‒F ).

Caudal sting very reduced, its mean length 6.2% DW [5.6‒7.1% DW] (smallest caudal sting among the three species of Paratrygon ); mean sting width 0.9% DW [0.8‒0.9% DW] ( Tab. 3). One female adult specimen (IAvH-P 4684) with lateral serrations of caudal sting poorly developed and present only on medial and distal portions ( Fig. 25A ). Juveniles with very few and poor developed lateral serrations, present only on third final portion of spine ( Figs. 25B‒D ).

Lateral line. Junction of four canals (JFC) of ventral lateral line in Paratrygon parvaspina longer than in P. orinocensis , with its posterior part formed by connection of hyomandibular (HMD) and infraorbital (IOC) canals, and its anterior extremity by the supraorbital ( SPO ) and nasal (NAS) canals connection ( Fig. 26 ). Angular (ang) and jugular (jug) components of HMD descend straight to posterior portion of disc, while in P. orinocensis these components show a conspicuous curve. Subpleural loop (spl) not so wide as in P. orinocensis , and with three short posterior subpleural tubules (pst), with most central one subdivided. Subpleural component (spc) ascends in straight line and begins an external curvature just before scapular girdle level. Subpleural tubules (spt) begin detaching from HMD at level of third pair of gill slits ( Fig. 26 ).

Infraorbital canal (IOC) descends from JFC as in P. orinocensis ; suborbital component (sub) with less honeycomb ramifications (mainly the small and anterior ones) than P. orinocensis ; sub presents two connection points with prenasal component (pnc) of nasal canal ( Fig. 26 ). Supraorbital canal ( SPO ) with orbitonasal component (orb) slightly curved, a broad prenasal loop (pnl), and with a nasointernal loop (nil) similar to P. orinocensis ; subrostral component (sbr) shorter than P. orinocensis , and with just five vesicles of Savi (vS) occurring next to nil ( Fig. 26 ).

Nasal canal (NAS) ascends from JFC similar as in P. orinocensis ; prenasal component (pnc) with a slightly internal curvature next to vesicles of Savi level. Mandibular canal (MNC) descends posteriorly from Meckel’s cartilage in straight line and externally curved next to adductor mandibulae muscle ( Fig. 26 ).

Skeleton. Meristic counts of vertebrae and radials of pectoral and pelvic fins just from MZUSP 117836 specimen ( Tab. 4). Differently from P. orinocensis , neurocranium of P. parvaspina not with an evident letter “T” format in dorsal view, with its preorbital process (PRP) extending laterally beyond nasal capsules (NC) level, being the widest portion of anterior part of neurocranium; orbit and otic capsules regions slighlty more robust in this species than in P. orinocensis , these regions not showing a clear difference in width with NC. Rostral projection (RPJ) also broad and with half circle format, with its tip reaching anterior level of NC s. Nasal capsules oval and separated by a large internasal septum (IS), not so encircled by first segment of propterygium (FSP) as in P. orinocensis ( Fig. 27 ). Supraorbital crest (SOC) with very evident small and triangular supraorbital process (SP). Frontoparietal component of fontanelle (FPF) in spoon format (posteriorly oriented), with its posterior portion wider than anterior and, broader and more developed than FPF of P. orinocensis ( Fig. 27 ). Mandibular arch very similar to P. orinocensis , with palatoquadrate (PQ) and Meckel’s cartilage (MC) slightly straighter in P. parvaspina , and MC slighlty robust, with its proximal portion (extremity which articulates with PQ and hyomandibula) wider than in that species. Hyomandibula (HYO) slightly curved in its medial part, and more robust than P. orinocensis ( Fig. 27 ).

Synarcual cartilage shorter and wider than P. orinocensis , with wider spinal nerve canal (SNC) than in that species. Dorsomedial crest (DMC) does not reach synarcual tip as in P. orinocensis ; dorsal socket (DS) in posterior region of synarcual cartilage deeper and tapered, anterior ventral condyle (AVC) with a convex surface (whereas AVC in P. orinocensis with straight surface), and posterior ventral condyle (PVC) also smaller than AVC. Lateral stay (LS) more expanded anterolaterally than in P. orinocensis ( Fig. 28 ). Scapulocoracoid with more robust and thicker coracoid bar (CB) than P. orinocensis ; anterior and posterior faces of CB respectively straight and curved in its central portions. Dorsolateral crest (DLC) of scapular process (SCP) not so pronounced as in P. orinocensis , and not passing laterally mesocondyle (MSC) level. Mesocondyle and metacondyle (MTC) slightly smaller and less projected than in P. oricocensis ( Fig. 29 ).

Propterygium (PPT) slightly more robust than in P. orinocensis , and slightly more arched in its distal portion. First segment of propterygium (FSP) one-fourth of PPT length, with just one pectoral radial directly connected ( P. orinocensis with two radials), and not encircling anteriorly the nasal capsules (NC) so closely as in P. orinocensis ( Fig. 30A ). Contact between small articulation surface (SAS) of PPT with mesopterygium (MSP) not so evident as in P. orinocensis ( Figs. 30A‒B ). Concavity of proximal face of MSP not so curved and pronounced as in P. orinocensis ; both extremities, anterior and posterior, contact respectively propterygium and metapterygium, however, junctions of medial radials (JMR) of pectoral fin appear only in anterior extremity of MSP ( Fig. 30B ). Metapterygium (MTP) more robust (mainly in its proximal portion), arched and slighlty shorter than in P. orinocensis ; posterior segments (PSM) also in pelvic girdle level ( Fig. 30C ).

Puboischiadic bar (PB), as in P. orinocensis , with arched shape, inclined and rectilinear in its anterior portion, and, its posterior portion presenting a curvature as a half circle (however slightly more closed than in that species). Iliac process (IP), ischial process (ISP) and lateral prepelvic process (LPP) slighlty less developed than P. orinocensis , and with more rounded tips. Three pairs of obturator foramina (OF) on lateral extremities of its PB ( Fig. 31 ).

Color in alcohol. Dorsal disc coloration gray or beige, with big dark and small light spots scattered all over dorsal disc ( Figs. 19A, C , 20A, C ). Dark spots in dark gray, dark brown or even black, with vermicular or dendritic format, slender or slightly thick in its central portions; spots more concentrated and smaller on disc margins. Light spots in light gray or light beige with rounded, oval or poligonal formats. Dorsal coloration of tail similar to disc, gray or beige with dark spots occurring from tail’s base to caudal sting insertion; posterior to caudal sting, tail in light beige or light gray with many small and dark gray, dark brown or even black specks. Ventral disc coloration in two tones: one light and predominant, white color, occurring on all central region, anterior margin and anterior portion of lateral margins of disc; and another one, slightly darker, beige or gray, occurring on posterior margins and posterior portion of lateral margins of disc; in this darker pattern occur numerous small and dark gray spots, with various formats, rounded, oval or vermicutale ( Figs. 19B, D , 20B, D ). Pelvic fins also with both tones present on disc, with light tone on anterior margin and on all central portion of pelvic fin, and darker one as a thin strip on posterior margin, slightly wider on posterior corner; darker areas also show small dark spots on pelvic fins as well as on disc. Clasper also with these two tones, with light one occurring just on base, and darker occurring on medial and terminal portions; darker tone on clasper without small dark spots. Ventral coloration on pre-caudal sting portion of tail with same light tone of disc; some specimens with gray spots. Posterior to caudal sting, ventral coloration of tail beige or gray, darker close to tail tip; tail tip with numerous small dark gray specks. As in P. orinocenis , the dorsal and ventral coloration of P. parvaspina is more intense and evident than in preserved specimens, especially concerning dorsal marks and spots.

Geographic distribution. Paratrygon parvaspina is also endemic to the Orinoco basin,

however with a more restricted distribution than P. orinocensis . Specimens analyzed in this study were collected in middle portion of the Orinoco River and its main affluents,

the Bita and Tomo rivers ( Fig. 32 ).

Etymology. From the Latin parvus, meaning small, and spina for spine; the epithet parvaspina refers to the diagnostic reduced caudal sting of this new species. Gender feminine. An adjective.

Figures

FIGURE 4 | Frontal view of eyes and spiracles of the three species of genus Paratrygon. Paratrygon orinocensis: A. IAvH-P 12449 (paratype), adult male, 573 mm DW, from Orinoco river. B. USNM 233944a (paratype). C. IAvH-P 11939 (holotype). Paratrygon parvaspina: D. IAvH-P 12447 (holotype), adult female, 450 mm DW, from Bita river. E. IAvH-P 12441 (paratype), juvenile female, 225 mm DW, from Tomo river. F. IAvH-P 12446 (paratype), juvenile male, 212 mm DW, from Tomo river. Paratrygon aiereba: G. MPEG uncatalogued, adult male, 578 mm DW, from Marajó island. H. MZUSP 14774, juvenile female, 256 mm DW, from Jutaí river. I. MUSM uncatalogued, juvenile male, 220 mm DW.

FIGURE 19 | Holotype and paratype of Paratrygon parvaspina. Holotype, IAvH-P 12447, adult female, 450 mm DW, from Bita river. A. dorsal and B. ventral views. Paratype, IAvH-P 12441, juvenile female, 255 mm DW, from Tomo river. C. dorsal and D. ventral views.

FIGURE 20 | Paratypes of Paratrygon parvaspina. IAvH-P 12446, juvenile male, 212 mm DW, from Tomo river. A. dorsal and B. ventral views. MZUSP 117836, juvenile female, 266 mm DW, from Orinoco river. C. dorsal and D. ventral views.

FIGURE 21 | Lateral view of spiracles and spiracles process of Paratrygon parvaspina. A. IAvH-P 4684, adult female, 345 mm DW, from Tomo river. B. IAvH-P 12441 (paratype). C. IAvH-P 12446 (paratype). D. MZUSP 117836 (paratype).

FIGURE 22 | Dermal denticles on the dorsal disc and tail of Paratrygon parvaspina, IAvH-P 12447 (holotype). A. distribution of dermal denticles. B. detail of some thorns with tubercular base on the posterior margin of the disc and tail’s basis. C. detail of basal plates of these tubercular spines. bp = basal plate.

FIGURE 23 | Dorsal view and details of central disc dermal denticles of Paratrygon parvaspina, MZUSP 117836 (paratype) (SEM images). A. and B. dorsal view of some denticles. C. dorsal and D. lateral details of central dermal denticles. ccp = central coronal plate, lcr = lateral coronal ridge.

FIGURE 24 | Dorsal and lateral rows of thorns in Paratrygon parvaspina. A. and B. IAvH-P 12447 (holotype). C. IAvH-P 4684. D. detail of dorsal pointed spines on the tail of IAvH-P 12441 (paratype). E. IAvH-P 12446 (paratype). F. MZUSP 117836 (paratype).

FIGURE 25 | Dorsal view of caudal stings of Paratrygon parvaspina. A. IAvH-P 4684. B. IAvH-P 12441 (paratype). C. IAvH-P 12446 (paratype). D. MZUSP 117836 (paratype).

FIGURE 26 | Ventral canals of lateral line system in Paratrygon parvaspina, IAvH-P 12446 (paratype). A. distribution of all ventral canals. B. detail of the anterior central disc ventral canals. Abbreviations see Fig. 12.

FIGURE 27 | Radiograph of neurocranium and mandibular arch of Paratrygon parvaspina, MZUSP 117836 (paratype), upper view. Abbreviations see Fig. 13. Arrow indicates to the anterior portion of specimen.

FIGURE 28 | Radiograph of synarcual cartilage of Paratrygon parvaspina, MZUSP 117836 (paratype), upper view. Abbreviations see Fig. 14. Arrow indicates to the anterior portion of specimen.

FIGURE 29 | Radiograph of scapulocoracoid of Paratrygon parvaspina, MZUSP 117836 (paratype), upper view. Abbreviations see Fig. 15. Arrow indicates to the anterior portion of specimen.

FIGURE 30 | Radiographs of basal elements of pectoral fin of Paratrygon parvaspina, MZUSP 117836 (paratype), upper view. Abbreviations see Fig. 16. Arrow indicates to the anterior portion of specimen. A. Propterygium region. B. Mesopterygium region. C. Metapterygium region.

FIGURE 31 | Radiograph of pelvic girdle of Paratrygon parvaspina, MZUSP 117836 (paratype), upper view. Abbreviations see Fig. 17. Arrow indicates to the anterior portion of specimen.

FIGURE 32 | Distribution of Paratrygon parvaspina throughout Orinoco basin. This species occurs in the mid portion of Orinoco river, and in some tributaries of this portion. Star = holotype specimen (IAvH-P 12447) locality.