Potamotrygon boesemani (Chondrichthyes: Myliobatiformes: Potamotrygonidae), a new species of Neotropical freshwater stingray from Surinam
Rosa, Ricardo S.
de Carvalho, Marcelo R.
Wanderley, Cristiane de Almeida
Neotropical Ichthyology
2008
2008-03-31
6
1
1
1
4M4QG
Rosa & de Carvalho & Wanderley, 2008
Rosa & de Carvalho & Wanderley
2008
[237,519,1003,1027]
Elasmobranchii
Potamotrygonidae
Potamotrygon
Animalia
Myliobatiformes
1
Chordata
species
boesemani
sp. nov.
Holotype. USNM 225574(male, 377 mmDW), Matapi Creek, ca. 1 kmfrom Corantijn River, Nickerie District, Surinam, 5º00’N 57º16’W, R. Vari et al., 9 Sep 1980. ( Figs. 1, 2). Paratypes. USNM 225216(female, 153 mmDW), stream about 0.5 kminland of Camp Mataway, Nickerie District, Surinam, 4º48’N 57º43’W, Vari et al., 12 Sep 1980; USNM 225575(male, 250 mmDW), Corantijn Riverat km 180, Nickerie District, Surinam, 5º08’N 57º18’W, R. Vari et al., 8 Sep 1980( Fig. 3); USNM 388849(male [ Fig. 4], 413 mmDW; female [ Fig. 5], 427 mmDW), same data as holotype. Non-type specimens. RMNH 26188(two females, 275 and 364 mmDW), tributary of Kabalebo river, ca. 8 mi.below Avanavero Falls, Corantijn riverdrainage, Surinam( Fig. 6); USNM 226191(male, 128 mmDW), same data as USNM 225575; USNM 226192(one male and two female embryos aborted by adult female), same data as USNM 225574; USNM 226193(two females, 134 and 150 mmDW), stream on south bank of Lucie River, ca. 6 kmupstream of ferry crossing on Amotopo-Camp Geol. Rd., Corantijndrainage, Nickerie District, Surinam, 3º36’N 57º37’W, R. Vari et al., 18 Sep 1980; USNM 226194(male, 163 mmDW), small creek entering Corantijn riveron east side approximately 300 m North of Amotopo Boat Landing, Nickerie District, Surinam, 3º33’N 57º40’W, R. Vari et al., 19 Sep 1980.
Diagnosis.Dorsal region of disc of dark brown background coloration, with deep orange to red ocellated spots of irregular form, encircled by relatively broad black rings, in irregular concentric series, and frequently in pairs around disc center; buccal cavity dark-pigmented with orange spots in adult specimens. This species is distinguished from the ocellated congeners P. motoro(Natterer in Müller & Henle), P. henlei(Castelnau), and P. leopoldiCastex & Castelloby the more intensely colored ocelli, which are usually yellow in the latter species. From P.motoro, it is also distinguished by the darker Fig. 1. Potamotrygon boesemani. Dorsal ( A) and ventral ( B) views of holotype (USNM 225574, 377 mm DW), Corantijn river. R. S. Rosa, M. R. de Carvalho & C. de A. Wanderley3 Fig. 3. Potamotrygon boesemani. Dorsal view of paratype (USNM 225575, 250 mm DW), from Corantijn river. Fig. 2. Potamotrygon boesemani. Detailed view of interorbital region ( A) and of mouth and nasal cavity ( B) of holotype (USNM 225574, 377 mm DW). dorsal background coloration, by the broader black contour of the dorsal ocelli, and by the irregular form of the ocelli as compared to the rounded shape in the latter species. From P. henleiand P. leopoldi, it is distinguished by the lack of ocelli on tail. From the tentatively identified specimen of P. ocellata(Engelhardt), which also has dark orange ocelli, the irregular contour of the ocelli in the new species is also distinctive. The teeth are relatively smaller and in greater number (up to 45 rows in the upper jaw) than in P.motoro(23 to 32) and P. ocellata( 24 inspecimen 190 mmDW). The number of pectoral-fin radials (98 to 104) is also slightly higher than in P. ocellata(94).
Description.Measurements are given in Table 1and counts in Table 2. Disc subelliptic, disc length 1.02-1.17 times its width. Tail flattened dorsoventrally, tail length 0.9-1.3 times DW in intact specimens. Dorsal surface of disc rough in adults, with denticles more developed and concentrated on midline and anterior portion. Tail with 12-27 median dorsal spines in young specimens and 28-42 inadults, in irregular rows; tail spines relatively high, acute and less curved when compared with congeners. Tail with well-developed lateral spines in adults, shorter than dorsal spines. One or two serrated caudal stings, inserted relatively close to tail base; sting length 1.6 to 2.5 times tail width. Eyes relatively large, eye length 1.6- 2.9 ininterorbital distance, 3.5-6.4 ininterocular distance. Spiracle length 1.4-2.1 times eye length, 2.0- 3.4 ininterspiracular distance. Mouth with five buccal papillae in all specimens; mouth width 9.2-13.6 inDW, 0.8-1.1 times internarial width. Teeth relatively small, set in quincunx, in 24 to 45 longitudinal rows in upper jaw, 24 to 43 inlower jaw, 5 to 10 exposed teeth in median row of lower jaw. Tooth rows increase in number with body size ( Fig. 7). Teeth sexually dimorphic, females and immature males with rhombic posterior margin, mature males with cuspidate posterior margin. Nostrils oblique to midline, nostril length 1.2-1.6 (x=1.4) in internarial distance, 2.3-2.9 (x=2.6) in prenarial distance. Branchial basket relatively broad, its greatest width at level of first pair of gill openings 3.6-4.2 inDW. Neurocranium ( Fig. 8) relatively long, cranium length 26.7- 27.7% DW (x=27.3, n=5, SD=0.4). Nasal capsules anteriorly convex with a median concavity between them; cranium width at nasal capsules 17.0-18.0% DW (x=17.5, n=5, SD=0.4). Preorbital processes laterally prominent and subtriangular; cra- 4 A new species of Neotropical freshwater stingray from Surinam Fig. 4. Potamotrygon boesemani. Dorsal ( A) and ventral ( B) views of paratype (USNM 388849, male, 413 mm DW), from Corantijn river. Fig. 5. Potamotrygon boesemani. Dorsal ( A) and ventral ( B) views of paratype (USNM 388849, female, 427 mm DW), from Corantijn river. R. S. Rosa, M. R. de Carvalho & C. de A. Wanderley5 nium width at preorbital processes 18.9-21.6% DW (x=20.3, n=5, SD=1.0). Supraorbital processes short; cranium width at supraorbital processes 9.8-10.4% DW (x=10.1, n=4, SD=0.3). Postorbital processes laterally expanded and flattened; cranium width at postorbital processes 20.2-22.0% DW (x=21.2, n=3). Cranial fontanelle elongate and anteriorly broad, with slight constriction between precerebral and frontoparietal portions; fontanelle length 16.6-17.9% DW (x=17.1, n=5, SD=0.5), fontanelle width 6.6-9.2% DW (x=7.7, n=5, SD=1.1). Antorbital cartilage triangular and elongated, tapering towards posterior end ( Fig. 8b). Upper jaws (palatoquadrates) slender and separated at symphysis. Lower jaws (Meckel’s cartilages) broad, stout and separated at symphysis; distance between lateral margins of lower jaws nearly equal to preorbital width of cranium. Hyomandibular cartilage slender and slightly arched at its anterior end. Two parallel angular cartilages at the articulation of hyomandibular cartilage and lower jaw. Claspers relatively long, clasper length in immature specimens 8.6 to 13.3 inDW, clasper length in adults 3.6-3.7 inDW. Table 1.Proportional measurements on specimens of Potamotrygon boesemani, as percent of disc width. Asterisks indicate the broken tail of the holotype (H). H n Range Mean SD Disc width (100%) 377 13 87-427 Disc length 110 13 102.2-117.1 108.41 4.39 Total length * 4 201.5-219.5 210.30 7.51 Disc length to axil of pectoral fin 95.4 13 86.3-105.1 93.99 5.16 Preoral length 19.1 13 19.1-24.5 21.85 1.72 Mouth to scapulocoracoid 34.7 13 30.5-37 33.25 2.18 Mouth to cloaca 65.5 13 60.5-70.8 64.63 2.73 Snout to cloaca 85.6 13 80.1-92.6 86.02 3.95 Cloaca to sting base 39.7 12 37.5-50.4 41.91 3.50 Tail length * 5 91.5-128.7 112.88 13.93 Sting length 23.2 12 16.5-26 22.17 3.32 Tail width at base 10.6 13 8.9-13.2 10.82 1.09 Tail width at insertion of sting 5.2 13 5-7.3 5.93 0.64 Tail height at base 5.7 13 5-8.8 6.61 1.13 Pelvic fin anterior margin 25.4 13 22.4-30.5 27.02 2.61 Pelvic fin posterior margin 26.5 13 18.7-27.1 22.52 2.50 Clasper length from cloaca 27.5 6 7.5-27.5 15.57 9.11 Eye diameter 3.6 13 3.1-6.3 4.66 1.09 Spiracle length 6.4 13 5.9-12 8.05 1.69 Preocular distance 26.6 13 25.5-29.9 25.31 7.72 Interorbital distance 9.0 12 8.8-11.2 10.08 0.89 Interocular distance 19.0 13 18.4-28.2 21.58 2.72 Interspiracular distance 20.1 13 19-24 20.93 1.31 Internarial distance 9.0 13 7.2-9.5 8.72 0.60 Mouth width 8.3 13 7.3-10.9 8.75 0.86 Nostril length 5.7 11 5.6-7.5 6.25 0.70 Distance between first pair of gill 26.3 13 23.5-27.9 26.02 1.39 slits Distance between first and fifth 15.5 13 14.5-17.6 16.22 0.94 gill slits Upper dental plate width 7.8 10 5.2-8.5 7.78 0.96 Lower dental plate width 6.6 10 5.2-8.2 7.31 0.89 Color in alcohol.Dorsal surface of disc with dark brown background coloration and deep orange to red ocellated spots of irregular format, surrounded by thick black rings. Black ring width usually equal to or larger than diameter of corresponding ocellus. Some ocelli with light yellow center, gradually darkening to orange towards margin. Some ocelli joined in pairs, mainly in disc center, where they are more irregularly shaped. Ocelli diminish in size towards disc margins. Dorsal surface of pelvic fins with same color as disc, bearing smaller 6 A new species of Neotropical freshwater stingray from Surinam Fig. 6. Potamotrygon boesemani. Dorsal views of non-type specimens (RMNH 26188), from Corantijn river: ( A) 275 mm DW; ( B) 364 mm DW. Table 2.Counts on specimens of Potamotrygon boesemani. Holotype n Range Mean SD propterygial radials 46-47 6 44-47 45.3 1.2 mesopterygial radials 16-16 6 14-19 16.5 1.4 metapterygial radials 38-38 6 37-41 38.7 1.2 total pectoral-fin radials 100-101 6 98-104 100.5 1.6 pelvic-fin radials (?) 20-20 3 20-22 21 0.8 pelvic-fin radials (?) - 3 24-27 25.1 1.1 precaudal vertebrae 27 6 27-30 28.1 0.9 caudal vertebrae 92 6 92-101 97.5 3.2 caudal vertebrae to insertion 72 6 63-73 69.2 3.6 of sting total vertebrae 119 6 119-129 125.7 3.5 diplospondylous centra - 2 0-12 - - centra in posterior synarcual 2 6 2-4 3.0 0.6 Fig. 7.Number of longitudinal tooth rows in upper (a) and lower (b) jaws of Potamotrygon boesemani, relative to disc width. Adjusted straight lines of both regression functions nearly coincident. orange ocelli and irregular lighter spots. Ventral surface of disc medially white and laterally with broad areas pigmented in dark brown, with scattered ocellated or vermiculated spots, ranging from light yellow to orange. Ventral disc surface of adult specimens usually with one central dark spot over pectoral girdle. Embryos and young specimens with completely creamy white ventral surface. Tail dark brown dorsally, with irregular orange spots but no large ocelli beyond its base. Lateral surface of tail with alternate black bars with white spots in the interspaces. Spiracular cavity, floor and ceiling of mouth cavity pigmented with dark and orange spots in adult specimens. Holotypewith dark pigment also in nasal cavity ( Fig. 2b). The coloration of preserved specimens does not differ significantly from freshly collected material, as confirmed by color slides taken in the field shortly after capture. Geographic Distribution. This species is known from the Corantijn riverdrainage, in Sipaliwiniand Nickeriedistricts, Surinam( Fig. 9).
Etymology.The specific name honors the late Dutch biologist Marinus Boeseman (1916-2006), who contributed substantially to our knowledge of both South American ichthyology (including chondrichthyans) and zoological history.
3313908305
1980-09-09
R
Suriname
Vari
5.0
Matapi Creek
1305
-57.266666
Corantijn River
1
USNM 225574
1
Nickerie
holotype
3313908306
1980-09-12
USNM
Suriname
4.8
Camp Mataway
1306
-57.716667
Vari
1
USNM 225216
1
Nickerie
paratype
3313908309
USNM
Suriname
5.133333
Corantijn River
1305
-57.3
1
USNM 225575
1
Nickerie
paratype
3313908302
[906,1230,376,397]
1980-09-08
R
Suriname
Vari
1
1
Nickerie
paratype
3313908310
1980-09-09
USNM
Suriname
Vari
5.0
Matapi Creek
1305
-57.266666
Corantijn River
1
USNM 388849
1
Nickerie
paratype
3313908312
RMNH
Suriname
Kabalebo river
Corantijn river
1
RMNH 26188
1
3313908308
USNM
Suriname
Kabalebo river
Corantijn river
1
USNM 226191
1
3313908303
USNM
Suriname
Kabalebo river
Corantijn river
1
USNM 226192
1
3313908301
USNM
Suriname
Corantijn
3.6
Lucie River
1307
-57.616665
Amotopo-Camp Geol. Rd.
1
USNM 226193
1
Nickerie
3313908311
1980-09-18
R
Vari
Suriname
1
1
Nickerie
3313908304
USNM
Suriname
300
3.55
Corantijn river
1307
-57.666668
North of Amotopo Boat Landing
1
USNM 226194
1
Nickerie
3313908307
1980-09-19
R
Vari
Suriname
1
1
Nickerie
3313908313
Suriname
Corantijn river
5
1
Sipaliwini