Gymnura lessae, Carvalho, 2017

Carvalho, Marcelo Rodrigues De, 2017, Taxonomic and morphological revision of butterfly rays of the Gymnura micrura (Bloch & Schneider 1801) species complex, with the description of two new species (Myliobatiformes: Gymnuridae), Zootaxa 4332 (1), pp. 1-74 : 20-34

Gymnura lessae , sp. nov.

( Figs. 11–20 , 34b , 36b – 38b , 42b – 44b , 46b – 48b ; Tabs. 3–4)

Pteroplatea maclura : Jordan & Gilbert, 1883: 46 (description, North America, distributional range including G. micrura ); Jordan & Evermann, 1896: 86 (description, North and Middle America, distributional range including G. micrura ); Linton, 1905: 348 (stomach contents, Beaufort, N. Carolina); Smith, 1907: 45 (description, North Carolina, maximum size probably wrong); Wilson, 1908: 626 (parasites, North Carolina); Weymouth, 1910: 135 (Louisiana); Coles, 1915: 94 (C. Lookout, North Carolina); Nichols & Breder, 1927: 27 (Sandy Hook Bay and Woods Hole).

Pteroplatea maclura (in part): Müller & Henle, 1841: 169 (description, only specimen(s) from New York); Duméril, 1865: 614 (description, only specimens from USA, size probably erroneous as the New York specimen recorded with a width of 2 meters is the same analyzed by Müller & Henle 1841, who had earlier termed it as small); Günther, 1870: 487 (description, only specimen from Texas).

Pteroplatea micrura: Garman, 1913: 414 , pl. 33, figs. 3–4 (description, color, illustration); Fowler, 1920: 146 (listed, C. May County, New Jersey); Hildebrand & Schroeder, 1928: 67, fig. 37 (description, Chesapeake Bay); Breder, 1931: 39 (listed, Sandy Hook Bay, New Jersey); Fowler, 1931: 46 (listed, Port Aransas, Texas); Beltran, 1934: 10 (listed, Mexico, not seen); Gunter, 1935: 39 (listed, Louisiana & Gulf of Mexico); Fowler, 1936: 132 (West Africa references for G. sereti , sp. nov., description of mid-Atlantic U.S. specimen); Gunter, 1941: 196 (listed, Louisiana).

Pteroplatea micrura (in part): Meek & Hildebrand, 1923: 87 (no Panama record, color description matching G. lessae , nov. sp., probable area of occurrence of G. micrura ).

Gymnura micrura: Bigelow & Schroeder, 1953: 408 –416, figs. 97, 98 (description, illustrations, U.S. [Gulf of Mexico and North Coast] and Mexico); Joseph & Yerger, 1956: 119 (biological notes, Alligator Harbor, Florida); Daiber & Booth, 1960: 138 –139 (biological notes, Delaware and Chincoteague Bays); Schwartz, 1961: 390 (size, embryos, listed, Chincoteague & Sinepuxent Bays); Hoese, 1962: 170 –171 (occurrence, Virginia’s Seaside); Snelson & Williams, 1981: 6, 8 (biological notes, Florida); Schmid et al. 1988: 123 –124 (biological notes, Florida); Wourms, 1993: 271, 283 (embryonic development, South Carolina); Maruska, 2001: 52, 55–57, 59, 62, figs. 6, 9b (lateral line canal system); Rosenberger, 2001b (locomotion, pectoral fin); González-Isáis, 2003: 260, 262, 264–266, 269–271, figs. 2a, 5 (cephalic musculature; Veracruz, Mexico); Wigley et al. 2003: 7, 17 (length-weight relationships, Northeast Coast of the U.S.); González-Isáis & Domínguez, 2004: 518, 521–524, 527, 528, 530, 532, tab. 1, figs. 3a, 4b, 5b, 6b, 7a, 9a (skeletal morphology, cephalic musculature; Veracruz, Mexico); Kobelkowsky, 2004: 185 –192, figs. 1–3 (morphology of urogenital system; Veracruz, Mexico); McEachran & Aschliman, 2004: 87, fig. 3.8 (clasper; Florida, Gulf of Mexico); Shepherd & Myers, 2005: 1097 – 1100, 1102 (population decline, Gulf of Mexico); Smith et al., 2009: 761 –763, 765, 766, 768, 772–778 (morphometry, molecular data); Schwartz, 2011: 35 –36 (distributional pattern, North Carolina); Kobelkowsky, 2012: 36, 38–41 (heart anatomy, Mexico); Cu-Salazar et al. 2014: 109 –117 (reproductive biology; Tabasco and Campeche, Mexico).

Gymnura micrura (in part): McEachran et al. 1996: 67 –68, 70–75, 83 (lateral line, skeletal morphology, cephalic and branchial musculature; only specimen TCWC 642.08 [Florida, Gulf of Mexico],?TCWC [uncataloged specimen]); Rosenberger, 2001a: 615, 616, 618, 620, 621, 623–627 (in systematics analysis; only specimen FMNH 46250 [Florida, Gulf of Mexico] and probably FMNH 40363 [ Dominican Republic],?FMNH 89992); McEachran & Carvalho, 2002: 577 (identification guide, illustration, Western Central Atlantic, G. micrura also included).

Gymnura altavela: Fowler, 1945: 162 (embryos, South Carolina , Bigelow & Schroeder analyzed the specimens and found them to be G. micrura [= G. lessae , sp. nov.]).

Holotype. USNM 51940 (420 mm DW, adult male), North Carolina , Beaufort, Collector: G. Bean, Accession num. 0 43551, USNM 440342 recatalogued from USNM 51940 ( Fig. 11 ).

Paratypes. USNM 440342 (4 specimens: adult male, 370 mm DW; adult male, 342 mm DW; juvenile female, 280 mm DW; skeleton of a dissected specimen), North Carolina , Beaufort, collector: G. Bean, accession num. 0 43551, date cat: 0 9 Feb 2017, recatalogued from USNM 51940 ( Figs. 12–14 )

Diagnosis. A medium size butterfly ray occurring in the central and northwestern Atlantic Ocean. Gymnura lessae , sp. nov. may be distinguished from other species of butterfly rays (except G. micrura and G. sereti , sp. nov.) by the combination of the following characters: absence of spiracular tentacle, caudal stings, and dorsal fin; tail relatively short (mean post-cloacal length 19% DW) and prominently banded, presenting 3 to 5 black bands that may be less distinct in large adults. Gymnura lessae , sp. nov. may be distinguished from G. micrura and G. sereti , sp. nov. by the dorsal contour of its hyomandibula with a conspicuous proximal protuberance followed by a inconspicuous distal protuberance (vs. dorsal contour of hyomandibula with two conspicuous protuberances); projection of the anteroventral fenestra on the floor of the coracoid bar taking the form of a funnel with relatively narrower opening and end (in G. micrura this projection takes the shape of a funnel with large opening and closing; in G. sereti , sp. nov. the funnel has a large opening, but presents an abrupt tapering at its half length, with the end of the funnel relatively narrow), and higher number of pectoral radials (ranges 118–127 vs. 112–119 in G. micrura and 109–115 in G. sereti , sp. nov.). Gymnura lessae , sp. nov. may be further distinguished from G. sereti , sp. nov. by the following characters: clasper of mature males more slender and longer, Lclasper 9.4–14.3% DW (vs. clasper stouter and shorter, Lclasper 6.8–9.2% DW); cranial fontanelle U-shaped (vs. keyhole-shaped); mesopterygium divided into one anterior solid element and 5–7 smaller fragments (vs. mesopterygium divided into two solid elements); distance between anteroventral and posteroventral fenestrae of scapulocoracoid representing 35–40% of scapulocoracoid length (vs. distance between AVF and PVF about 20% of scapulocoracoid length); lateral projection of the base of synarcual starting at its anterior third (vs. lateral projection of the base of synarcual starting at its half length); lower number of diplospondylous vertebrae (means 97 vs. 110), and higher number of radials in the mesopterygial fragments compared to the second mesopterygial element of G. sereti , sp. nov. (ranges 14–19 vs. 10–15). Gymnura lessae , sp. nov. is most similar to G. micrura , and may be further differentiated from it by its brownish dorsal side with a vermiculate background (vs. dorsal side usually uniformly brown or gray without any vermiculate pattern).

Description. Measurements are presented in Table 3; meristic data in Table 4. The following description is based on all specimens examined. Throughout the text the proportions are presented as: minimum value–maximum value (mean). See Figs. 11–17 , 18a , and 19 and 20 for external morphology and color, Fig. 34b for ventral lateralline pattern and Figs. 18b , 36b – 38b , 42b – 44b and 46b – 48b for skeletal morphology.

External morphology. Disc lozenge shaped, 1.54–1.94 (1.75) times broader than long [1.54–1.70 (1.61) for adult males; 1.71–1.89 (1.80) for adult females]. Trunk strongly flattened, slightly raised above scapular region and posterior head. Snout relatively short and obtuse with a subtle lobe at snout tip. Sexual dimorphism evident in disc shape mainly between adults, with adult males presenting proportionally longer snouts with smaller angles, which confers a triangular shape to the anterior half of their disc ( Fig. 15 ). Preoral snout length 7.6–16 (12)% DW [8–11 (10)% DW in adult females; 13–16 (14)% DW in adult males], preorbital snout length 6.8–14 (9.7)% DW [7–9 (8)% DW in adult females; 10–14 (12)% DW in adult males], preorbital snout width 31–41 (36)% DW, postspiracle snout width 40–54 (48)% DW. Anterior margins of disc with a slight medial concavity and becoming weakly convex towards extremities (in adult males these curves may be less noticeable, with the anterior margins almost straight in some males) ( Fig. 15 ); pectoral-fin apices acutely angular (sometimes moderately angular in adult males); posterior margins weakly convex; free rear tip broadly rounded; axis of greatest width positioned posteriorly to disc half-length. Pelvic fin single lobed, rectangular, their corners rounded ( Fig. 16 ). Skin entirely smooth, without denticles on the dorsal and ventral surface of the disc.

Interorbital space broad, interorbital width 7.4–10 (8.6)% DW. Eyes dorsolateral, small, oval and protruding slightly ( Fig. 17a ); eye diameter 1.1–2.2 (1.7)% DW, representing 11.5–26.3 (19.5)% of interorbital width; orbit diameter 2–3.9 (2.8)% DW, representing 61–175 (96)% of spiracle length. Eyes more protruded and relatively larger in embryos. Spiracles immediately posterior to eyes, relatively large, lozenge-shaped, contour of the inner spiracular margin concave to rectilinear ( Figs. 17b, c ); spiracle length 2.1–3 (1.8)% DW, 1.1–3 (1.8) times eye diameter; its inner posterior margin without tentacles.

Ventral head length 20–28 (23)% DW. Nostril narrowly oval, diagonally directed, only the circular distal margin not covered by nasal curtain, posterior lateral margin with lobe; nostril length 2.0–4.1 (3.2)% DW [2.7–3.4 (3.1)% DW in adult females; 3.1–4.1 (3.5)% DW in adult males], 0.9–2.7 (1.7) times internasal width; internasal width 1.4–3.1 (1.9)% DW. Anterior nasal flaps medially expanded and fused into a broad, skirt-shaped, posteriorly expanded nasal curtain that covers internasal space and reaches mouth ( Fig. 17d ). Nasal curtain skirt shaped, weakly to moderately bilobed, wide, its width 2.4–4.3 (3.1) times its length; lateral margin concave; posterolateral apices rounded; posterior margin straight to weakly concave, a small medial gap may be present.

Mouth relatively wide, its width 7.9–11 (9.1)% DW, 30–48 (39)% head length, 0.9–1.7 (1.2) times nasal curtain width; without papillae on floor or labial folds, although some striations may originate radially from mouth corners ( Fig. 17d ); lower lip arched rearward toward corners, uniformly convex or weakly to moderately concave along medial region, without any lump or knob ( Fig. 17d ); a strip of corrugate skin forms a half circle below mouth, ending at mouth corners. Small, numerous and closely crowded teeth in bands; teeth similar to teeth in G. micrura , with one medial, pointed cusp directed towards inside of mouth and the base somewhat expanded, entirely twisted in opposite direction; in labial face, tooth resembling a three-armed boomerang; teeth similar between jaws and sexes, their number increasing with growth.

Gill slits moderately S-shaped, first four gill slits markedly larger than fifth ( Fig. 17d ). Distance between gill slits decreasing posteriorly; distance between inner ends of fifth pair 62–79 (73)% distance between inner ends of first pair; distance between inner ends of first pair 15–19 (16) % DW, 57–84 (70)% ventral head length, 4.8–13.0 (8.5) times internasal width; distance between inner ends of fifth pair 10–13 (12)% DW, 40–60 (51)% ventral head length, 4.0–9.2 (6.2) times internasal width.

Tail slender and short, whip-like, cross-banded (see color description), tapering toward tip, without caudal stings and dorsal fin ( Figs. 20d, e ); postcloacal tail 15–24 (19)% DW, 28–42 (34)% DL, 32–48 (39)% precloacal length; low longitudinal skin folds present on dorsal and ventral surfaces, skin folds not reaching tail tip.

Clasper of mature males cylindrical, somewhat depressed, relatively slender and long (compared to G. sereti , sp. nov.) ( Fig. 18 ); distance from posterior margin of cloaca to clasper tip 9.4–14.3 (11.9)% DW; clasper tapering slightly distally; tip conical, bluntly pointed to pointed, not calcified; non-calcified portion relatively long compared to G. micrura , but shorter than in G. sereti , sp. nov.; apopyle (on the anterior dorsal surface) connected to hypopyle by a long, dorsomedial, posteriorly curved clasper groove; spermatic duct ending before reaching clasper tip; rhipidion and pseudorhipidion absent; a long ventral pseudosiphon laterodistally situated to hypopyle; welldeveloped dorsal pseudosiphon on inner margin of clasper, dorsal pseudosiphon more posteriorly located when compared to G. sereti , sp. nov.; ventral surface of clasper entirely smooth.

Coloration. Dorsal side brownish, grayish or purplish, vermiculated. The vermiculate pattern varying from less conspicuous with lighter and darker shades to a conspicuous pattern where the lighter areas become larger and more remarkable ( Figs. 19a–h ), with light bands regularly distributed on outer anterior margins of disc ( Figs. 20a, b ). Living specimens may vary their color according to the environment, but maintain the color pattern described above when preserved. Ventral surface whitish to brownish, copper; generally darkening toward edges. Tail prominently cross-banded, with 3–5 black bands ( Fig. 20d ); bands diffuse or less distinct in large specimens ( Fig. 20e ).

Size, reproduction, diet and habitat. Small juveniles with 168, 171 and 174 mm DW from Gulf of Mexico and Bahamas were analyzed by us, at the same time we have observed term embryos from Virginia and North Carolina ranging from 235 to 258 mm DW, so the birth size may be estimated as ranging from 170 to 260 mm DW. The largest juvenile male was 342 mm DW (FLMNH 45943, Georgia), while the smallest adult male measured 274 mm DW (BMNH 1948.8.6.20, Texas). Three individuals with 306, 333 and 333 mm DW were near maturity; all males larger than 342 mm DW were adults. The maturation size of males is estimated between 270–340 mm DW. The largest male analyzed by us measured 420 mm DW. Schwartz (2011) mentioned males up to 609 mm DW, which should be close to the maximum size for males of this species. Bigelow & Schroeder (1953) state that females produce young when reaching 625–650 mm DW, and maybe even smaller. Daiber & Booth (1960) reported that a female with 669 mm DW was becoming sexually mature and observed pregnant females only with 800 mm WD. Cu-Salazar et al. (2014), working in the southern Gulf of Mexico, estimated the size at 50% maturity at 568 mm DW. Therefore, the size at maturity should be between 550–600 mm DW. The largest female examined by us was 732 mm DW (FLMNH 29943, Florida, Atlantic coast), and the largest female reported that could be referred with confidence to the present species rather than to G. altavela measured 899 mm DW ( Hoese 1962). Females of G. lessae , sp. nov. should attain a maximum breadth of 1000–1100 mm. Schwartz (2011) comments on a female of 1660 mm DW caught in North Carolina, a size that is well above the size that has been undoubtedly reported for this species (as G. micrura ). Individuals from North Carolina, Virginia and regions farther north reach larger sizes (birth, maturity and maximum) than individuals from Gulf of Mexico. The species is matrotrophic viviparous (lipid histotrophy). Bigelow & Schroeder (1953) suggest that the young are produced from late May through July and into August, and perhaps even later in the season. Daiber & Booth (1960) indicate that pregnancy occurs during the summer months for this species. In the few analyzed stomachs were found fishes, crustaceans, mollusks and other invertebrates ( Bigelow & Schroeder 1953, Daiber & Booth 1960, Schmid et al. 1988). Also a demersal species, living along the coast on sandy and muddy bottoms.

Geographical distribution. Gymnura lessae , sp. nov. is distributed in the north and central western Atlantic from Woods Hole in southern Massachusetts and Buzzards Bay to the Gulf of Mexico (including the Gulf Coast of the United States and Mexico) ( Fig. 21 ). Both previously unidentified specimens from Bahamas and Jamaica (SMF 2398 and ZMB 34702, respectively) were classified by the discriminant model as G. lessae , sp. nov. (99.9 and 99.8% probability, respectively), so the distributional range of the species may be extended to the northern Caribbean Sea. The occurrence of G. lessae , sp. nov. in North Carolina and regions farther north seems to be seasonal, related to summer months ( Bigelow & Schroeder 1953). The northernmost specimen analyzed in this study was MNHN 7938 from New York, however there are records of the species (as G. micrura ) from Chincoteague, Sinepuxent and Delaware Bays, Cape May and Sandy Hook Bay (New Jersey), New York, Narragansett and Buzzards Bays, and Woods Hole (Massachusetts) ( Daiber & Booth 1960, Schwartz 1961, Fowler 1920, Nichols & Breder 1927, Breder 1931, Müller & Henle 1841, Bigelow & Schroeder 1953). Although we have not analyzed any specimens from Mexico, the species is commonly caught in Mexican waters of the Gulf of Mexico ( Bigelow & Schroeder 1953, González-Isáis 2003, González-Isáis & Domínguez 2004, Kobelkowsky 2004, Cu-Salazar et al. 2014).

Etymology. The name lessae is a tribute to Dr. Rosângela Lessa, a highly esteemed Brazilian researcher who has been struggling valiantly for the conservation of sharks and rays in Brazil, and has contributed significantly to the knowledge of this group. Prof. Rosângela Lessa has been a valued mentor and friend of the first author.

Remarks. Müller & Henle (1841) included the specific name maclura in G. micrura , their material of which comprised both G. micrura and G. lessae (these authors also included G. poecilura in G. micrura ; see above). This error was perpetuated by subsequent studies until the end of the 1930s ( Duméril 1865, Günther 1870, Jordan & Gilbert 1883, Jordan & Evermann 1896, Linton 1905, Smith 1907, Wilson 1908, Weymouth 1910, Fowler 1913, Gudger 1913, Coles 1915, Breder 1926, Nichols & Breder 1927, Breder & Nigrelli 1934, Puyo 1936, Breder 1938). Raja maclura (= Gymnura maclura ) was described by Lesueur (1817) from the Northeastern coast of North America and is a synonym of the Atlantic congener G. altavela (e.g. Krefft & Stehmann 1973), so this name may not be applied to the form described herein as G. lessae .

Material examined (94 specimens). New York, USA (1 specimen): MNHN 7938 (juvenile female, 215 mm DW), 40o40’01”N, 73o49’59”W. Delaware, USA (7 specimens): ANSP 121562 (3 embryos: female, 204 mm DW; male, 208 mm DW; female, 219 mm DW), S. of Old Bare Shoal, mouth of Delaware Bay; USNM 187293 (4 embryos: 59–64 mm DW), Indian River Inlet. Virginia, USA (9 specimens): USNM 19480 (juvenile female, 285 mm DW), eastern shore of Virginia; USNM 25452 (male, 390 mm DW), Willoughby Point; USNM 26551 (juvenile female, 327 mm DW), Willoughby Point; USNM 42502 (adult male, 402 mm DW), Cape Charles; USNM 169930 (2 specimens: male, 355 mm DW; female, 366 mm DW), Chesapeake Bay, East shore of Hampton Roads Beach, just below Willoughby Bay; USNM 196538 (3 embryos: 235–244 mm DW), Accomack Co., mouth of inlet Chincoteague Bay. North Carolina, USA (22 specimens): AMNH 44039 (juvenile male, 312 mm DW), Carteret, Beaufort, bogue sound; AMNH 220825 (juvenile female, 253 mm DW), 36o32’N, 75o47’W; AMS IA-78 (adult male, 440 mm DW), Beaufort; AMS IA-79 (adult male, 396 mm DW), Beaufort; ANSP 167406 (juvenile male, 270 mm DW), flats south of Pirer Isle, Beaufort; CAS 19834 (juvenile female, 296 mm DW), Beaufort Harbor, 34o43’28”N, 76o39’56”W; CAS 19835 (juvenile male, 244 mm DW), Beaufort Harbor, 34o43’28”N, 76o39’56”W; CSIRO H7510.01 (juvenile female, 258 mm DW), NE of Albemarle Sound, 36o34’N, 75o46’W; CSIRO H7511.01 (adult male, 363 mm DW), Pamlico Sound, 35o51–53’N, 75o32–33’W; FLMNH 5412 (juvenile female, 312 mm DW), Carteret Co. about 1 mi off Beaufort Inlet, 34o40’44”N, 76o40’32”W; FLMNH 45942 (adult male, 339 mm DW), Carteret, Onslow Bay, 34o40’30”N, 76o51’30”W; FLMNH 184152 (2 specimens: juvenile female, 269 mm DW; juvenile female, 258 mm DW), off Cape Lookout; NCSM 49395 (2 specimens: juvenile female, 292 mm DW; juvenile male, 290 mm DW), Carteret Co., beach near Bridge Pier in Bogue Banks, Morehead City; SU 10839 (juvenile male, 289 mm DW), Beaufort Harbor, Beaufort, Carteret, 34o42’40”N, 76o38’38”W; SU 10841 (juvenile male, 308 mm DW), Beaufort Harbor, Beaufort, Carteret, 34o42’40”N, 76o38’38”W; USNM 19680 (male, 350 mm DW), Beaufort; USNM 51897 (juvenile male, 338 mm DW), Beaufort; USNM 89937 (2 embryos: female, 120 mm DW; male, 117 mm DW), Pivers Island, Beaufort; ZMH 10329 (embryo female, 101 mm DW), Carteret Co. South Carolina, USA (7 specimens): AMNH 73805 (juvenile female, 268 mm DW), North Inlet, Jones Creek, 33o18’N, 79o10’W; AMNH 73872 (subadult male, 333 mm DW), North Inlet, Old Man Creek, Georgetown, 33o20’08”N, 70o10’05”W; AMNH 73890 (adult male, 338 mm DW), North Inlet, Town Creek, Georgetown, 33o20’N, 79o10’W; AMNH 73915 (adult male, 348 mm DW), North Inlet, Town Creek, Georgetown, 33o20’N, 79o10’W; USNM 26524 (2 specimens: juvenile male, 257 mm DW; adult male, 300 mm DW), Charleston; USNM 25988 (juvenile female, 200 mm DW), Charleston. Georgia, USA (2 specimens): FLMNH 29977 (female, 368 mm DW), Glynn, Jekyll Island, 31o03’44N”, 81o24’44”W; FLMNH 45943 (juvenile male, 342 mm DW), Camden, St. Andrews Sound off Jekyll Island, 30o59’48”N, 81o24’32”W. Florida, USA (20 specimens): AMNH 84277 (2 specimens: adult male, 308 mm DW; not measured), Gulf of Mexico, Sarasota, North end of Siesta Key; FLMNH 25979 (2 specimens: not measured), Gulf of Mexico, Franklin County, mud cave on Alligator Harbor, 29o53’45”N, 84o21’32”W; FLMNH 29943 (adult female, 732 mm DW), Brevard County, Mosquito Lagoon, 28o42’30”N, 80o42’00”W; FLMNH 29981 (adult female, 695 mm DW), Volusia County, N. end of Mosquito Lagoon, near Oak Hill, 28o51’30”N, 80o49’00”W; FLMNH 51071 (cleared & stained, 3 specimens), Gulf of Mexico, Franklin County, Alligator Harbor 100–300 yd. W of FSU Marine Lab, 29o54’52”N, 84o30’36”W; FLMNH 73634 (3 term embryos, 145–164 mm DW), Gulf of Mexico, Franklin County, Apalachicola Bay, ca. 1 mi E. of Bob Sikes Cut on St. George Isl., 29o36’50”N, 84o57’33”W; FLMNH 233554 (female, 495 mm DW), Miami- Dade Co., Biscayne Bay from UMIM, 25o42’43”N, 80o14’25”W; LACM 2462 (juvenile male, 222 mm DW), Gulf of Mexico, vicinity of Fort Walton Beach, 30o24’08”N, 86o37’17”W; LACM 38147-2 (jaws), Gulf of Mexico, Franklin Co., end of Alligator Harbor; SMF 6992 (adult female, 600 mm DW), Sarasota, Gulf of Mexico; SU 14336 (adult male, 312 mm DW), Gulf of Mexico, Sanibel Island, Tarpon Bay, 26o27’19”N, 82o04’31”W; USNM 127298 (juvenile male, 217 mm DW), Apalachicola Bay, Gulf of Mexico; USNM 127300 (juvenile female, 223 mm DW), Apalachicola Bay, Gulf of Mexico; USNM 127302 (juvenile male, 220 mm DW), Apalachicola Bay, Gulf of Mexico. Alabama, USA (1 specimen): AMNH 86386 (adult male, 414 mm DW). Mississippi, USA (1 specimen): USNM 143221 (female, 327 mm DW), Mississippi Miss. Sound, Eastend, Gulf of Mexico. Louisiana, USA (5 specimens): USNM 131275 (juvenile female, 201 mm DW), one mi. S. of Wine Island, Gulf of Mexico; USNM 155734 (adult male, 336 mm DW), off northern edge of Chandeleur Islands, Gulf of Mexico, 30o05’N, 88o50W; USNM 157745 (2 term-embryos?: male, 195 mm DW; female, 201 mm DW), off the Mississippi River Delta, Gulf of Mexico, 29o15’N, 88o48W; USNM 186406 (juvenile female, 174 mm DW), Grand Island, Gulf of Mexico. Texas, USA (16 specimens): ANSP 53264 (juvenile female, 235 mm DW), Port Aransas; BMNH 1948.8.6.20 (adult male, 274 mm DW), Rockport; BMNH 1948.8.6.21 (female, 561 mm DW), Rockport; SU 38663 (juvenile male, 214 mm DW), Aransas Pass; USNM 94545 (2 specimens: adult male, 327 mm DW; adult male, 337 mm DW), from the vicinity of Corpus Christi, Gulf of Mexico; USNM 116452 (6 specimens: female, 397 mm DW; juvenile male, 244 mm DW; juvenile male, 253 mm DW; subadult male, 294 mm DW; adult male, 288 mm DW; juvenile male, 306 mm DW), Galveston, Gulf of Mexico; USNM 118613 (juvenile male, 195 mm DW), Galveston, Gulf of Mexico, 28o17’16”N, 94o48’48”W; USNM 121611 (2 specimens: juvenile male, 263 mm DW; juvenile male, 266 mm DW), Galveston, Gulf of Mexico; USNM 127073 (juvenile female, 287 mm DW), off Galveston, Gulf of Mexico. Gulf of Mexico (1 specimen): USNM 160832 (adult male, 396 mm DW). Bahamas (1 specimen): SMF 2398 (juvenile female, 171 mm DW). Jamaica (1 specimen): ZMB 34702 (juvenile female, 219 mm DW).

Figures

FIGURE 11. Dorsal (A) and ventral (B) views of holotype of Gymnura lessae, sp. nov. (USNM 51940, adult male, 420 mm DW).

FIGURE 12. Dorsal (A) and ventral (B) views of Gymnura lessae, sp. nov. (paratype, USNM 440342, adult male, 370 mm DW).

FIGURE 13. Dorsal (A) and ventral (B) views of Gymnura lessae, sp. nov. (paratype, USNM 440342, adult male, 342 mm DW).

FIGURE 14. Dorsal (A) and ventral (B) views of Gymnura lessae, sp. nov. (paratype, USNM 440342, juvenile female, 280 mm DW).

FIGURE 15. Specimens of Gymnura lessae, sp. nov., dorsal view. A) Adult male, 440 mm DW (AMS IA- 78); B) Adult female, 695 mm DW (FLMNH 29981); C) Juvenile male, 244 mm DW (CAS 19835); D) Juvenile female, 296 mm DW (CAS 19834).

FIGURE 16. Ventral view of pelvic fin of Gymnura lessae, sp. nov. A) Male (AMNH 84277, unregistered size); B) Female (CAS 19834, 296 mm DW).

FIGURE 17. Morphological details of Gymnura lessae, sp. nov. A) Dorsal view of head (CSIRO H 7511.01, 363 mm DW); B) Detail of eye and spiracle, showing straight contour of inner margin of spiracle (CSIRO H 7511.01); C) Detail of eye and spiracle, showing concave contour of inner margin of spiracle (AMNH 84277); D) Ventral view of head (paratype, USNM 440342, 280 mm DW).

FIGURE 18. Clasper of Gymnura lessae, sp. nov. A) Illustration in dorsal view, right clasper, showing external morphology; B) Radiograph, dorsoventral view (holotype, USNM 51940) showing skeleton. Abbreviations: ap, apopyle; at, accessory terminal cartilage; ax, axial cartilage; B, beta cartilage; b 1, first basal segment; b 2, second basal segment; cg, clasper groove; dp, dorsal pseudosiphon; DT 1, dorsal terminal 1 cartilage; DT 2, dorsal terminal 2 cartilage; hpp, hypopyle; pf, pelvic fin; VM, ventral marginal cartilage; vp, ventral pseudosiphon; VT, ventral terminal cartilage.

FIGURE 19. Dorsal view of disc of Gymnura lessae, sp. nov., showing variation in vermiculate color pattern. B, D, F and H are amplifications of the white squares in A, C, E and G, respectively. A. NCSM 49395, 292 mm DW; C. AMNH 84277, 308 mm DW; E. CSIRO H 7511.01, 363 mm DW; G. FLMNH 29981, 695 mm DW.

FIGURE 20. Specimens of Gymnura lessae, sp. nov., showing variation in dorsal color. A) Dorsal view of anterolateral disc region showing light bands on outer anterior margin of disc (CAS 19834, 296 mm DW); B) Dorsal view of head showing light bands on outer anterior margin of disc (CSIRO H 7511.01, 363 mm DW); C) Detail of central region of dorsal disc showing vermiculate pattern (USNM 26551, 327 mm DW); D) Tail cross-banded (CAS 19834, 296 mm DW); E) Tail of a larger specimen, with diffuse, less distinct bands (FLMNH 29981, 695 mm DW).

FIGURE 21. Map showing geographical distribution of Gymnura lessae, sp. nov. Black star represent approximate locality of holotype, red circles represent approximate localities of material examined in the present study; grey circles represent approximate localities based on literature (as G. micrura; Fowler 1920, Nichols & Breder 1927, Breder 1931, Müller & Henle 1841, Bigelow & Schroeder 1953, Daiber & Booth 1960, Schwartz 1961, González-Isáis 2003, 2004, Kobelkowsky 2004, Cu- Salazar et al. 2014). B is a detailed view of darker rectangle in A. Localities may represent more than one specimen. Abbreviations: NC, North Carolina; VA, Virginia; DE, Delaware; NJ, New Jersey; PA, Pennsylvania; NY, New York; MA, Massachusetts.

FIGURE 34. Ventral lateral line system. A) Gymnura micrura (RN F 43, female, 339 mm DW); B) Gymnura lessae, sp. nov. (NCSM 49395, female, 292 mm DW); C) Gymnura sereti, sp. nov. (FLMNH 29993, juvenile male, 290 mm DW). Subpleural tubules omitted. Canals on the left side not shown in their entirety. Differences between species observed in the pictures but not mentioned in the text were not considered consistent enough to be diagnostic. Colors: red, hyomandibular canal; green, infraorbital canal; brown, supraorbital canal; blue, nasal canal; yellow, prenasal canal. inl, innernasal loop; lh, lateral hook; pl, prenasal loop; spl, subpleural loop.

FIGURE 36. Outline of dorsal cranial fontanelle, dorsal view. A) Gymnura micrura (ANSP 120086, 185 mm DW); B) Gymnura lessae, sp. nov. (USNM 155734, 336 mm DW); C – D) Gymnura sereti, sp. nov. (C. BMNH 1963.8. 9.3, 337 mm DW; D. FMNH 118133, 368 mm DW).

FIGURE 38. Mandibular arches, radiograph, dorsoventral view. A) Gymnura micrura (USNM 222622, 323 mm DW); B) Gymnura lessae, sp. nov. (USNM 25452, 390 mm DW) C) Gymnura sereti, sp. nov. (holotype, USNM 193741, 383 mm DW). Abbreviations: ap, anterior process; hyo, hyomandibula; mc, Meckel’s cartilage; pq, palatoquadrate; tb, tooth band. Black arrows indicate the most convex dorsal portion of the palatoquadrate; white arrow indicates the furrow at the ventral border of palatoquadrate of G. lessae.

FIGURE 42. Synarcual cartilage (radiograph, dorsolateral view). A) Gymnura micrura (USNM 222622, 323 mm DW); B) Gymnura lessae, sp. nov. (SU 14336, 312 mm DW); C) Gymnura sereti, sp. nov. (holotype, USNM 193741, 383 mm DW). Abbreviations: assp, articular surface for scapular process; isv, intersynarcual vertebrae; lap, lateral anterior process; ls, lateral stay; mdc, medial crest; op, odontoid process; sc, suprasynarcual cartilage; snf, spinal nerve foramina; sp, scapular process; scp, scapulocoracoid. Arrows indicate the point where the synarcual base projects laterally and extends posteriorly.

FIGURE 44. Scapulocoracoid (radiograph, dorsoventral view). A) Gymnura micrura (USNM 222622, 323 mm DW); B) Gymnura lessae, sp. nov. (CSIRO H 7511.01, 363 mm DW); C) Gymnura sereti, sp. nov. (holotype, USNM 193741, 383 mm DW). Abbreviations: adf, anterodorsal fenestra; avf, anteroventral fenestra; co, coracoid cartilage; fmes, fragments of mesopterygium; mes 1, mesopterygium 1; mes 2, mesopterygium 2; met, metapterygium; msc, mesocondyle; mtc, metacondyle; pc, procondyle; pdf, postdorsal fenestra; pro, propterygium; S, synarcual; ssc, suprascapular cartilage.

FIGURE 46. Radiograph of head region (dorsoventral view) showing the arching of propterygium and shape of the inner space between propterygia (black line). A) Gymnura micrura (USNM 222622, 323 mm DW); B) Gymnura lessae, sp. nov. (CSIRO H 7511.01, 363 mm DW); C) Gymnura sereti, sp. nov. (holotype, USNM 193741, 383 mm DW). Abbreviations: anto, antorbital cartilage; f, fontanelle; mc, Meckel’s cartilage; mes, mesopterygium; nc, nasal capsule; pq, palatoquadrate; pro, propterygium; rad, radials; scp, scapulocoracoid; S, synarcual.

FIGURE 48. Pelvic girdle and pelvic fin (radiography, dorsoventral view). A) Gymnura micrura (USNM 222622, 323 mm DW); B) Gymnura lessae, sp. nov. (holotype, USNM 51940, 420 mm DW); C) Gymnura sereti, sp. nov. (holotype, USNM 193741, 383 mm DW). Abbreviations: bpt, basipterygium; ip, iliac process; isp, isquial process; lpp, lateral prepelvic process; of, obturator foramina; pb, puboischiadic bar; ppp, medial prepelvic process; ppv, pelvic propterygium; rad, radials.