Gymnura sereti, 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 : 35-46

publication ID

https://doi.org/10.11646/zootaxa.4332.1.1

publication LSID

lsid:zoobank.org:pub:C7D6FF64-5813-4AAB-AE40-C24ABB74433F

persistent identifier

https://treatment.plazi.org/id/03A787B2-FFBF-FFE8-A2BE-8B1035E5FE19

treatment provided by

Plazi

scientific name

Gymnura sereti
status

sp. nov.

Gymnura sereti , sp. nov.

( Figs. 22–31 View FIGURE 22 View FIGURE 23 View FIGURE 24 View FIGURE 25 View FIGURE 26 View FIGURE 27 View FIGURE 28 View FIGURE 29 View FIGURE 30 View FIGURE 31 , 34c View FIGURE 34 , 36c, d View FIGURE 36 , 37c View FIGURE 37 , 38c View FIGURE 38 , 42c View FIGURE 42 , 43c, d View FIGURE 43 , 44c View FIGURE 44 , 46c View FIGURE 46 – 48c View FIGURE 48 ; Tabs. 5, 6)

Pteroplatea micrura: Ehrenbaum, 1914 : (listed, Cameroon); Ehrenbaum, 1915: 73 (listed, Cameroon);? Barnard, 1925: 80 (description, reported from Agulhas Bank);? Monod, 1927: 650 (W. Africa, not seen).

Gymnura micrura: Fischer et al. 1981: 223 –224 (identification guide, Eastern Central Atlantic); Cappetta, 1984: 634, pl. 1, fig. 9 (teeth morphology, Ivory Coast); McEachran & Séret, 1990: 65 (checklist, Eastern Tropical Atlantic); Bianchi, 1986: 117 (identification guide, Angola); Séret & Opic, 1997: 68 –69 (identification guide, Tropical West Africa); Albaret et al. 2004: 41 (listed, Gambia estuary).

Holotype. USNM 193741 View Materials (383 mm DW, adult male), Liberia, off St. Paul River, 7-13 m, 0 6 Jan 1953, accession num. 202912 ( Fig. 22 View FIGURE 22 ).

Paratypes. USNM 193896 (338 mm DW, adult male), Liberia, Bushrod Island Beach, collector: G. Miller, 30 Oct 1952, field # 1791, accession num. 202912, date cat. 0 9 Jul 1963 ( Fig. 23 View FIGURE 23 ); USNM 279558 View Materials (289 mm DW, female), Sierra Leone, St. Anne Banana Islands, collector: G. Naylor, Feb 1986, field # 27, accession num 369276, remarks: from Sierra Fishing Co. (free town, Sierra Leone ) ( Fig. 24 View FIGURE 24 ) ; MNHN 1989-1216 (500 mm DW, adult male), Senegal, Bandiala, 15o00’00”N, 18o00’00”W, estuary, 14m, sector 3423, collectors: Cauri, Séret, 0 7 May 1983, n. station 02; MNHN 1989-1225 (gravid female, 665 mm DW with 3 embryos: female, 79 mm DW; male, 81 mm DW and male, 85 mm DW), Senegal, Saloum, Missira, 15o00’00”N, 18o00’00”W, estuary, 4–10m, sector 3423, collectors: Cauri, Séret, 0 7 May 1983, trawl, n. station 4; MNHN 1989-1229 View Materials (juvenile female, 324 mm DW), Ivory Coast, 0 5o 04’59”N, 0 3o 48’00”W, marine, 15m, sector 3434, donation: Campagne Chalci, n. 291, collectors: Andre Nizery, Camp. Chalci, Mar 1979, trawl, n. station 88 GoogleMaps ; MNHN 1989-1238 (juvenile male, 290 mm DW), Senegal, Saloum, Bandiala, 15o00’00”N, 18o00’00”W, estuary, 7–12m, sector 3423, collectors: Cauri, Séret, 0 7 May 1983, trawl, n. station 0 1.

Diagnosis. A medium size butterfly ray occurring in the eastern central Atlantic. Gymnura sereti , sp. nov. is distinguished from other species of butterfly rays (except G. micrura and G. lessae ) by the combination of the following characters: absence of spiracular tentacle, caudal stings and dorsal fin; tail relatively short (mean postcloacal length 24% DW), and prominently banded, presenting 3 to 6 (often 4) black bands that may be less distinct in large adults. Gymnura sereti , sp. nov. is distinguished from G. micrura and G. lessae by the following characters: clasper of mature males stouter and shorter, Lclasper 6.8–9.2% DW (vs. clasper slender and longer, Lclasper 9.3– 11% DW in G. micrura and 9.4–14.3% DW in G. lessae ); cranial fontanelle keyhole-shaped (vs. U-shaped); mesopterygium divided into two solid elements (vs. mesopterygium divided into one anterior solid element and 5– 7 smaller fragments); distance between anteroventral and posteroventral fenestrae of scapulocoracoid about 20% of scapulocoracoid length (vs. distance between AVF and PVF 30–40% of scapulocoracoid length); lateral projection of synarcual base starting at its half length (vs. lateral projection of the base of synarcual starting at its anterior third); higher number of diplospondylous vertebrae (mean 110 vs. 98 and 97 in G. micrura and G. lessae , respectively), and lower number of radials in the posterior mesopterygial element compared to the mesopterygial fragments in G. micrura and G. lessae (range 10–15 vs. 15–17 and 14–19 in G. micrura and G. lessae , respectively). Gymnura sereti , sp. nov. is further distinguished from G. micrura by its dorsal side brownish with a vermiculate background (vs. dorsal side usually uniformly brown or gray, without any vermiculate pattern), and basipterygium representing <50% of pelvic propterygial length (vs. basipterygium representing>60% of pelvic propterygial length). Gymnura sereti , sp. nov. is further distinguished from G. lessae by the dorsal contour of its hyomandibula with two conspicuous protuberances (vs. dorsal contour of the hyomandibula with a conspicuous proximal protuberance followed by a inconspicuous distal one) and lower number of pectoral radials (range 109–115 vs. 118–127). Other differences discussed in the text.

Description. Measurements are presented in Table 5; meristic data in Table 6. The following description is based on all specimens examined. Throughout the text the proportions are presented as: minimum value–maximum value (mean). See Figs. 22–28 View FIGURE 22 View FIGURE 23 View FIGURE 24 View FIGURE 25 View FIGURE 26 View FIGURE 27 View FIGURE 28 , 29a View FIGURE 29 , 30 View FIGURE 30 and 31 View FIGURE 31 for external morphology and color, Fig. 34c View FIGURE 34 for ventral lateral line pattern and Figs. 29b View FIGURE 29 , 36c, d View FIGURE 36 , 37c View FIGURE 37 , 38c View FIGURE 38 , 42c View FIGURE 42 , 43c, d View FIGURE 43 , 44c View FIGURE 44 and 46c View FIGURE 46 – 48c View FIGURE 48 for skeletal morphology.

External morphology. Disc lozenge shaped, 1.63–1.89 (1.77) times broader than long [1.64–1.76 (1.72) for adult males; 1.72–1.82 (1.79) 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. Although adult males present proportionally longer snouts, sexual dimorphism is not so evident in disc shape, and adult males do not possess a triangular anterior half of disc as observed in G. micrura and G. lessae ( Fig. 25 View FIGURE 25 ). Preoral snout length 8.7–13 (11)% DW [9–12 (10)% DW in adult females; 11–13 (12)% DW in adult males], preorbital snout length 7.1–11 (9)% DW [8–9 (8)% DW in adult females; 9–11 (10)% DW in adult males], preorbital snout width 34–44 (39)% DW, postspiracle snout width 48–57 (52)% DW. Anterior margins of disc with a medial concavity, becoming weakly convex towards extremities; pectoral-fin apices acutely angular; posterior margins convex; free rear tip broadly rounded; axis of greatest width positioned posterior to the half length of disc. Pelvic fin single lobed, rectangular, with rounded corners ( Fig. 26 View FIGURE 26 ). Skin entirely smooth, without denticles on the dorsal and ventral surfaces of the disc.

Interorbital space broad, interorbital width 8.4–11 (9.4)% DW. Eyes dorsolateral, small, oval, and protruding slightly ( Fig. 27 View FIGURE 27 ); eye diameter 0.9–2.2 (1.5)% DW, representing 9–23 (15)% of interorbital width; orbit diameter 1.7–3.2 (2.3)% DW, representing 41–94 (71)% of spiracle length. Eyes more protruded and relatively larger in embryos. Spiracles posterior to eyes, relatively large, lozenge-shaped, contour of the inner margin rectilinear to slightly concave ( Fig. 27 View FIGURE 27 ); spiracular length 2.3–4.2 (3.4)% DW, 1.6–4.1 (2.4) times eye diameter; its inner posterior margin without tentacles.

Ventral head length 21–26 (23)% DW. Nostril narrowly oval, diagonally directed, only the circular distal margin not covered by nasal curtain, posterior lateral margin with lobe; nostril length 2.7–4.3 (3.4)% DW, 1.0–2.2 (1.7) times internasal width; internasal width 1.6–2.7 (2.0)% 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. 28a View FIGURE 28 ). Nasal curtain skirt-shaped, weakly to moderately bilobed, wide, its width 2.5–4.1 (3.2) 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 7.6–9.9 (8.7)% DW, 31–42 (38)% head length, 1.0–1.4 (1.2) times nasal curtain width, without papillae on floor or labial folds, although some striations may originate radially from mouth corners; lower lip arched rearward toward corners, medial region moderately ( Fig. 28b View FIGURE 28 ) to strongly concave ( Fig. 28c View FIGURE 28 ); when strongly concave, medial region limited by angular projections which may form prominent rounded lumps or knobs ( Fig. 28d View FIGURE 28 ). A patch of corrugate skin forms a half circle below mouth, ending at mouth corners.

Small, numerous and closely crowded teeth in bands; teeth with one medial, pointed cusp directed towards inside of mouth; base somewhat broad, not twisted, practically straight; labial face of teeth T-shaped ( Fig. 28e View FIGURE 28 ); 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. 28a View FIGURE 28 ). Distance between gill slits decreasing posteriorly; distance between inner ends of fifth pair 58–74 (66)% distance between inner ends of first pair; distance between inner ends of first pair 16–19 (17)% DW, 67–84 (74)% ventral head length, 6.3–11.0 (8.7) times internasal width; distance between inner ends of fifth pair 10–13 (11)% DW, 42–54 (49)% ventral head length, 4.1–7.2 (5.7) times internasal width.

Tail slender and short, whip-like, cross-banded (see color section), tapering toward tip, without caudal stings or dorsal fin ( Fig. 31 View FIGURE 31 ); postcloacal tail 16–28 (24)% DW, 28–49 (42)% DL, 32–59 (50)% precloacal length; embryos with proportionally longer tails, postcloacal tail 29–35 (31)%; low longitudinal skin folds present on dorsal and ventral surfaces, skin folds not reaching tail tip.

Clasper of mature males cylindrical, somewhat depressed, relatively stout and shorter (compared to G. micrura and G. lessae ) ( Fig. 29 View FIGURE 29 ); distance from the posterior margin of cloaca to clasper tip 6.8–9.2 (8)% DW; tip somewhat depressed, rounded to bluntly pointed, not calcified; non-calcified portion relatively long when compared to G. micrura and G. lessae ; apopyle (on the anterior dorsal surface) connected to hypopyle by a long, dorsomedial, posteriorly curved clasper groove; spermatic duct ending well before reaching clasper tip; rhipidion and pseudorhipidion absent; a long ventral pseudosiphon laterodistally situated to hypopyle; a well-developed dorsal pseudosiphon on inner margin of clasper, the dorsal pseudosiphon more anteriorly located when compared to G. micrura and G. lessae ; ventral surface of clasper entirely smooth.

Coloration. Freshly caught specimens not analyzed, description based on preserved specimens from collections. Dorsal side brownish, vermiculated (similar to G. lessae ). 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. 30a–f View FIGURE 30 ). Light bands may be regularly distributed on outer margins of disc ( Fig. 30g View FIGURE 30 ) and round white spots may be present on disk ( Fig. 30h View FIGURE 30 ). Like its congeners, this species probably has the ability to vary its shade according to the bottom. Ventral surface whitish to brownish, creamy; generally darkening toward edges. Tail prominently cross-banded, with 3–6 black bands, often 4 ( Fig. 31a View FIGURE 31 ); a black dot may be present between the black bands ( Fig. 31b View FIGURE 31 ); bands less distinct in large specimens ( Fig. 31c View FIGURE 31 ).

Size. One litter presents embryos 183–199 mm DW without external yolk sac, but with the intestine full of yolk, while a term embryo 212 mm DW was found. The smallest juvenile analyzed measured 182 mm DW. Birth size is estimated around 180–220 mm DW. The largest juvenile male analyzed was 450 mm DW, while the smallest adult male was 338 mm DW. A 362 mm DW male was maturing, and all males larger than 450 mm DW were mature. The size at maturity of males should be around 300–450 mm DW. The largest male examined measured 560 mm DW ( AMNH 9897). The smallest gravid female examined was 665 mm DW ( MNHN 1989-1225), and the largest female examined (also pregnant) was 748 mm DW ( MNHN 1989-1247). This species should reach about 1000–1100 mm DW.

Geographical distribution and habitat. According to material examined, G. sereti , sp. nov., inhabits the West African coast from Senegal to Angola (south to Baía Farta, Benguela Province) ( Fig. 32 View FIGURE 32 ). A butterfly ray supposedly without spiracular tentacles, identified as Pteroplatea micrura , was recorded from Agulhas Bank, South Africa, by Barnard (1925). This may be the southernmost record of G. sereti , sp. nov. However, we can not confirm this since in the description of the genus provided in the same study, the author mentions that its tail has a sting; also, G. natalensis (commonly occurring in this area) may have extremely reduced spiracular tentacles, potentially a source of confusion with G. sereti , sp. nov. This species inhabits sandy and muddy bottoms in inshore waters, also entering estuaries.

Etymology. This species is a tribute to Dr. Bernard Séret, in honor of his important contributions to the systematics of elasmobranchs and to our knowledge of West African fishes. Bernard has contributed substantially to the collections of the MNHN, including thousands of specimens from West Africa, and is an esteemed friend of the second author.

Material examined (55 specimens). Senegal (8 specimens): FLMNH 176854 View Materials (female, 541 mm DW), Djifère , Djifère Senegal market ; MNHN 1989-1214 View Materials (juvenile male, 220 mm DW), estuary of Saloum river , 15o00’00”N, 18o00’00”W GoogleMaps ; MNHN 1989-1215 View Materials (adult male, 468 mm DW), estuary of Saloum river , 15o00’00”N, 18o00’00”W GoogleMaps ; MNHN 1989-1217 View Materials (adult male, 535 mm DW), estuary of Saloum river , 15o00’00”N, 18o00’00”W GoogleMaps ; MNHN 1989- 1218 View Materials (male, 510 mm DW), estuary of Saloum river , 15o00’00”N, 18o00’00”W GoogleMaps ; MNHN 1989-1220 (juvenile male, 207 mm DW), 12o58’01”N, 16o52’59”W; MNHN 1989-1223 View Materials (adult male, 451 mm DW), estuary of Saloum river , 15o00’00”N, 18o00’00”W GoogleMaps ; MNHN 1989-1224 View Materials (adult male, 404 mm DW), estuary of Saloum river , 15o00’00”N, 18o00’00”W GoogleMaps . Guinea-Bissau (5 specimens): MNHN 1989-1232 View Materials (gravid female, 730 mm DW with 3 embryos), Cacheu, 12o12’00”N, 16o 10’ 0 1 ” W GoogleMaps ; MNHN - 1235 (juvenile male, 246.5 mm DW), Cacheu, 12 o 12 ’ 0 0 ” N, 16o10’01”W GoogleMaps . Sierra Leone (2 specimens): FLMNH 29993 View Materials (2 specimens: juvenile male, 290 mm DW; female, 512 mm DW), upper Sierra Leone River, 0 8o 34’30”N, 13o06’00”W GoogleMaps . Liberia (3 specimens): BMNH 1911.6 .30.6 (juvenile male, 200 mm DW), Axim , Gold Coast ; USNM 222623 View Materials (2 specimens: female, 289 mm DW; female, 311 mm DW), 0 6o 18’N, 10o49’W GoogleMaps . Ivory Coast (5 specimens): MNHN 1989-1219 View Materials (juvenile male, 249 mm DW), 0 5o 04’59”N, 0 3o 48’00”W GoogleMaps ; MNHN 1989-1226 (female, 476 mm DW), 0 5o12’00”N, 0 4o21’00”W; MNHN 1989- 1227 (adult male, 397 mm DW), 0 5o12’00”N, 0 3o49’01”W; MNHN 1989-1240 (adult male, 432 mm DW), 0 5o12’00”N, 0 4o21’00”W; MNHN 1989-1242 (juvenile male, 213 mm DW), 0 5o04’59”N, 0 3o48’00”W. Ghana (3 specimens): BMNH 1930.3 .24.4 (juvenile male, 236 mm DW), Accra , Gold Coast; BMNH 1930.8 .26.9 (juvenile female, 184 mm DW), Accra , Gold Coast; USNM 222600 View Materials (juvenile female, 182 mm DW), Tema, Teshie Bay . Togo (13 specimens): MNHN 1989-1244 View Materials (female, 660 mm DW), 0 6o 13’01”N, 0 1o 37’59”E GoogleMaps ; MNHN 1989-1245 (gravid female, 692 mm DW with 4 embryos: male, 183 mm DW; male, 186 mm DW; male, 199 mm DW and male, 212 mm DW), 0 6o13’01”N, 0 1o37’59”E; MNHN 1989-1247 (gravid female, 748 mm DW with 4 embryos: female, 134 mm DW; female, 140 mm DW; female, 144 mm DW and male, 145 mm DW), 0 6o13’01”N, 0 1o37’59”E; SMF 3992 (female, 284 mm DW); SMF 3993 (juvenile male, 283 mm DW). Republic of Benin (4 specimens): MNHN 1967-0737 View Materials (juvenile male, 207 mm DW), 0 6o 19’01”N, 0 2o 24’00”E GoogleMaps ; MNHN 1969-0211 (3 specimens: juvenile male, 250 mm DW; juvenile male, 306 mm DW; juvenile male, 319 mm DW), 0 6o21’00”N, 0 2o54’00”E. Nigeria (2 specimens): MNHN 1985-0217 View Materials (female, 297 mm DW), 0 3o 49’59”N, 0 6o 13’59”E GoogleMaps ; USNM 198011 View Materials (female, 299 mm DW), vicinity of Lagos . Cameroon (1 specimen): ZMH 10333 View Materials (juvenile male, 261 mm DW), Duala . Gabon (1 specimen): MNHN 1985-0237 View Materials (juvenile male, 284 mm DW), 0 0o 00’00”N, 0 5o 00’00”E GoogleMaps . Angola (6 specimens): AMNH 9897 (adult male, 560 mm DW); FMNH 188133 View Materials (juvenile male, 368 mm DW); MB 2106 (subadult male, 362 mm DW), enseada Mucula; MB 2279 (adult male, 489 mm DW), Baía da Caota, Baía Farta ; MB 2297 (adult male, 490 mm DW); MB 2364 (female, 514 mm DW), Catumbo Dande , Bengo . West Africa (2 specimens): ZMB 8868 View Materials (female, 267 mm DW), Loango Coast ; BMNH 1963.8.9.3 (female, 337 mm DW).

PVF

Pusat Veterinaria Farma

AMNH

American Museum of Natural History

MNHN

Museum National d'Histoire Naturelle

ZMH

Zoologisches Museum Hamburg

Kingdom

Animalia

Phylum

Chordata

Class

Elasmobranchii

Order

Myliobatiformes

Family

Gymnuridae

Genus

Gymnura

Loc

Gymnura sereti

Carvalho, Marcelo Rodrigues De 2017
2017
Loc

Gymnura micrura:

Albaret 2004: 41
Seret 1997: 68
McEachran 1990: 65
Bianchi 1986: 117
Cappetta 1984: 634
Fischer 1981: 223
1981
Loc

Pteroplatea micrura: Ehrenbaum, 1914

Monod 1927: 650
Barnard 1925: 80
Ehrenbaum 1915: 73
1915