Peprilus xanthurus (Quoy & Gaimard, 1825)

(Fig. 2, Tables 3, 6)

Seserinus xanthurus Quoy & Gaimard, 1825: 384. [Type locality: Rio de Janeiro Bay. Syntypes: MNHN 0000-4060 (1), A- 5326 (1)].— De Lanois, 1963: 222 [MNHN type catalog].— Fowler, 1906: 119 [listed].

Rhombus xanthurus Cuvier & Valenciennes, 1833: 405 [description].— Jordan & Evermann 1896: 966 [comparison with Rhombus paru; distribution; synonymy].

Stromateus paru Fordice, 1884: 313 [in part; synonymy of R. xanthurus and R. argentipinnis; southward to Brazil].—von Ihering, 1897: 43 [in part; occurrence, Rio Grande do Sul; synonymy of Stromateus gardenii and S. alepidotus].— Pozzi & Bordale, 1935: 164 [in part; occurrence; Argentina, 35o30´S to 38o30’ S].

Seserinus paru, Fowler, 1916: 402 [in part; listed].— Fowler, 1942: 142 [error in spelling of generic name; referable to Seserinus xanthurus Quoy and Gaimard, 1824].

Peprilus paru, Meek & Hildebrand, 1925: 411 [in part].

Simobrama xanthura Fowler, 1944: 1 [new genus; description].

Peprilus xanthurus De Buen, 1950: 105 [Mar del Solias, Uruguay].

Seserinus paru Ringuelet & Aramburu, 1961: 83 [in part; Argentina].

Simobrama xanthurus Ringuelet & Aramburu, 1961: 83 [Argentina].

Peprilus paru (not of Linnaeus, 1758).—Miranda Ribeiro, 1915: 4 [description; distribution; comments on Sesserinus xanthurus].— Haedrich, 1967: 106 [in part; revision; synonymy]; Horn, 1970: 202 [in part; revision; synonymy].— Haedrich & Horn, 1972: 32 [in part; identification key; distribution, New York to Argentina].— Cervigón & Cousseau, 1971: 22 [in part; ichthyological collection Instituto de Biologia Marina, Mar del Plata, Argentina].— Menni et al., 1984: 196, 328 [in part; Uruguay and Argentina; illustrated].— Cerqueira & Haimovici, 1990: 599 −613 [in part; Rio Grande do Sul, Brazil; population dynamics].— Haimovici et al., 1994:66 [in part; fishes of Brazil Subtropical Convergence Ecosystem].— Lopes, 1992: 99 −100 [distribution; southeastern Brazilian coast, Baía de Guanabara].— Figueiredo & Menezes, 2000: 32 [in part; description; distribution], 98 [Fig. 32; Santa Catarina].— Menezes, 2003: 104 [in part; Brazilian coast].— Bernardes et al., 2005: 260 [southern Brazilian coast; description and photograph].— Azevedo et al., 2007: 10 −14 [southeastern Brazil, Rio de Janeiro; parasitology].— Mabragaña et al., 2011: 9 [in part; barcoding; fishes of Argentina].— Fischer, Pereira & Vieira, 2011: 101 [in part; Patos Laguna, Rio Grande do Sul, Brazil].

Diagnosis. Peprilus xathurus differs from its congeners by the presence, mainly in fresh specimens, of a conspicuous dark spot over the eyes, from snout to nape (vs. inconspicuous or indistinct marking in all other representatives, Fig. 2 e, f), 11−12 pre-caudal vertebrae (vs. 13 or more, rarely 12 in all other representatives, except P. x an t hu r u s, Table 3), 28−29 vertebrae (vs. 30 or more vertebrae in P. medius, P. ovatus, P. simillimus, and P. snyderi, Table 3), body height 58.5−74.1% SL (vs. 33.0−52% SL in P. bu r t i, P. ovatus, P. simillimus, P. s n y d er i, and P. triacanthus), moderately falcate dorsal fin (vs. not falcate in P. triacanthus, or conspicuously falcate in P. p ar u Figs. 2, 4), anal fin falcate (vs. not falcate P. simillimus, P. ovatus, P. snyderi, P. bu r t i, and P. t r i a c an t hu s, Fig. 2), and no series of pores along the front half of the body under the dorsal fin (vs. 17−25 conspicuous pores in P. triacanthus). Peprulis xanthurus is further distinguished from sympatric P. crenulatus by specimens smaller than 110 mm SL, with orbital diameter 5.1−8.0 in anal-fin height (vs. 1.6−5.0 in P. xanthurus, Fig. 3 a), and 5.5−9.2 in the specimens larger than 109 mm SL (vs. 3.2−5.2, Fig. 3 a), in the specimens larger than 109 mm SL, the orbital diameter 3.9−5.9 in pectoral-fin height (vs. 3.2−3.8 in P. xanthurus, Fig. 3 b), in the specimens larger than 109 mm SL, the orbital diameter 1.5−2.3 in post-orbital length (vs. 1.1−1.4, rarely 1.5, in P. xanthurus, Fig. 3 c). Peprulis crenulatus is additionally distinguished from C. paru by having moderately long to short dorsal fin and relatively long caudal fin lobe, the length of the lower lobe of the caudal fin is more than 1.2 times the length of the dorsal fin (vs. 1.2 times the length or less) (Figs. 1, 4).

Molecular diagnosis. The DNA barcode of P. xanthurus form a distinct cluster with genetic distances to all other representatives ranging from 9.0 to 13.0% (excluded P. ovatus from the Pacific coast of Mexico, and P. snyder from the eastern Pacific; Fig. 5). The genetic distance to P. crenulatus is 13.0%, and 10.0% to P. burti and P. paru (Table 4). The P. xanthurus haplotypes differ from those of all other members of the genus (excluded P. ovatus from the Pacific coast of Mexico and P. snyderi from the eastern Pacific) by 48 to 74 bases, 74 from P. crenulatus, 60 from P. burti and 58 from P. p ar u (Table 5).

Description. Morphometric data in Table 6, meristic data in Table 3. Counts D. III −IV.39 −47; A. II −III. 36 −42; P. 20−22; vertebrae 11−12+ 17−19; gill rakers 2−6+13−16. Body compressed, short and very deep. Dorsal profile steep at snout, convex from eye to origin of dorsal fin, descending, convex along dorsal base to caudal peduncle. Ventral profile steep to convex from snout to origin of anal fin, with small concavity in front of anal fin, ascending, mildly convex along anal fin base to caudal peduncle. Head, dorsum and nape with vertical rows of branched, subdermal canals. Head deep, with very short snout and small mouth, barely reaching anterior border of eye, upper jaw fixed, very slender, with teeth long, conical or tricuspid in upper jaw, conical in lower jaw. Eye lateral and small, slightly closer to ventral margin than dorsal margin, post-orbital region larger than eye diameter.

Peprilus xanthurus

Opercle with prominent lobe on posterior margin, sometimes with concavity on posterodorsal margin. Scales cycloid, small, deciduous on flanks and dorsal and anal fin bases to nape, present also on belly, under eye (4−5 horizontal rows) and preopercle, absent from pectoral base and opercle. Dorsal fin base long and falcate, anteriorly with small, plate-like spines partially embedded in skin. Pectoral fin falcate, 2nd and 3rd rays longest. Caudal peduncle short and relatively deep. Anal fin base longer than dorsal fin, very falcate. Caudal fin very forked, upper lobe slightly longer than lower lobe. Lateral line very arched in small individuals, less so in larger individuals, with 67−85 small scales, some of them pored, in upper margin of caudal peduncle.

Coloration of the fresh specimens. Upper head half dark gray, with a red-tinged snout in some specimens, upper third of trunk grayish blue, flanks silvery white. Dorsal fin dusky, sometimes with a light yellow hue, darker on the anterior rays, distal margin of soft rays black; anal fin gray, some specimens with yellow hue at base of the longer soft rays and black distal margin; pectoral fin dusky, darker at the tip, upper rays and base in some specimens. Caudal fin dirty yellowish, dusky on tips (Fig. 2 e, f).

Coloration of the preserved specimens. Brown with a silvery hue on the flanks, some specimens have small, black irregular spots on the snout, and others on the upper opercular margin. Dorsal and anal fins dusky, longer soft rays darker, pectoral fin dusky, with many melanophores on the base, upper rays and inter-radial membranes. The caudal fin is hyaline (Fig. 2 c, d).

Morphological variation. Significant variation in found in the development of P. xanthurus in the 70 to 194 mm SL size interval (Fig. 6), with negative or positive allometry in 14 of the 22 characters examined (Table 6, Fig. 7). Small specimens possess a deeper head and body (Fig. 7 b, c), larger eyes and wider mouth (Fig. 7 a, d). Negative allometry was observed in the pre-pectoral distance and dorsal fin height (Fig. 7 e, g). The distance between the snout to dorsal fin is the only character with positive allometry (Fig. 7 f). Similarly, P. x a nt h ur u s was characterized by isometric growth in the caudal peduncle height and post-orbital distance, whereas in P. crenulatus, these morphometric variables were positively allometric (Fig. 7 i, h).

Significant variation was observed in the anterior third of the lateral line profile, which is very curved in the small specimens and slightly curved in the large individuals, possible as a result of positive allometry in the ontogeny of the predorsal distance (Figs. 2 g, h, 3f).

Sexual dimorphism. Sexual dimorphism was observed between five females (126−206 mm SL) and five males (155−198 mm SL) in five morphological features (Fig. 2 e, f). The anterior portion of the body is longer in the males in comparison with the females, as shown by the distance from the tip of the snout to the dorsal fin (31.2 to 34.8% Sl vs. 27.8−31.8% Sl). Females have a taller body and broader head, as indicated by the body depth (63.9−72.7% Sl vs. 58.6−68.5% Sl) and interorbital distance (9.4−10.4% Sl vs. 9.1−9.8% Sl) and mouth width (7.1−8.4% Sl vs. 6.9−7.3% Sl). The dorsal fin base in longer in females than males (64.7−67.3% Sl vs. 60.2−63.8% Sl).

Distribution and habitat. Peprilus xanthurus occurs from Isla Margarita in Venezuela to Argentina (11°N to 38°S), inhabiting estuarine and coastal marine waters at depths of up to 95 m (Fig. 8 b). The species is very rare or absent on the northern and northeastern Brazilian coast (4°N to 13°S), but very common between the Brazilian state of Bahia-Espírito Santo and São Paulo (15° to 25°S), where it forms large schools and is caught in large quantities by trawlers, and abundant in local fish markets (A. Marceniuk, pers. obs.).

Remarks. Quoy & Gaimard (1825) described Seserinus xanthurus based on two specimens collected in Rio de Janeiro Bay, Brazil. The examination of the type specimens indicated that P. xanthurus is a valid species (Fig. 2 a), based on the relatively high anal fin to orbital diameter ratio, of 5.1−5.5 (vs. 3.2−5.0, rarely 5.1, in P. crenulatus). The type specimens also present a large dark spot from snout to nape (Fig. 2 a, e, f). The species status of P. xanthurus is further corroborated by the absence of P. crenulatus between Cape Frio, Rio de Janeiro and Paraná (23 o S to 25 o S), including the type locality of P. xanthurus (Fig. 8).

Bernardes et al. (2005) identified a specimen of Peprilus xanthurus based on the presence of a long falcate anal fin, and the smaller eye in comparison with the post-orbital region, a conspicuous characteristic in the adult specimens. Figueiredo & Menezes (2000) and Fischer et al. (2011) also contain images of specimens with a long, falcate anal fin and small eyes, similar to Peprilus xanthurus.

Material examined: Type specimens: MNHN 4060 Rio de Janeiro Bay, Brazil; MNHN 3326 Rio de Janeiro Bay, Brazil.

Non-type specimens. Venezuela: LBP 18874 (1, 135 mm SL), Isla Margarita, mouth of Rio Nueva Esparta. Brazil; MZUSP 60879 (1, 89 mm SL), Corumbau extractive reserve, Abrolhos, Bahia; MZUSP 67597 (1, 125.2 mm SL), 19 o25' S, 39 o35' W, 15 m deep, Espírito Santo, north to rio Doce; CIUFES 654 (2, 82− 146 mm SL), Camburi beach, Vitória, Espírito Santo; AZUSC s/n (3, 144− 166 mm SL), Vitória, Espírito Santo; MZUSP 67657 (2, 79− 84 mm SL), São João da Barra, Rio de Janeiro; MZUSP 67596 (3. 90−100 mm SL), Cabo de São Tomé, Rio de Janeiro; NPM 1914 (1, 99 mm SL), in front of the mouth of the rio Macaé, Macaé, Rio de Janeiro; LBP 8641 (1, 109− 152 mm SL), 23°30'22.6'' S, 45°02'01.7'' W, Ubatuba, São Paulo; LBP 10045 (2, 134− 186 mm SL), 23°51'38.7" S, 46°09'10.5" W, Bertioga, São Paulo; AZUSC 747 (3, 82− 129 mm SL), 23o57' 00'' S, 46 o03'30'' W, Indaíá beach, Bertioga, São Paulo; AZUSC 720 (4, 99− 140 mm SL), 23 o 53' 00'' S, 46o02' 00'' W, São Paulo; MZUSP 67584 (1, 88 mm SL), Bertioga, São Paulo; AZUSC 1402 (3, 81−104), 23o59' 00'' S, 46o08'00'' W, Arvoredo island, Guarujá; AZUSC 838 (1, 92 mm SL), 23o54'30'' S, 46o07'42'' W, Iporanga beach, Guarujá, São Paulo; LBP 10031 (2, 167− 194 mm SL), 24°37'00" S, 46°08'00" W, Santos, São Paulo; AZUSC 1333 (2, 142− 160 mm SL), 24o15'30'' S, 46o34'10'' W, Mongaguá, São Paulo; MPEG apm 432 (5, 122− 172 mm SL), industrial fishery, São Paulo; MZUSP 67632 (1, 160 mm SL), 27o33'S, 48o1'W, Santa Catarina; MZUSP 67672 (1, 91.8 mm SL), 28o26' S, 48o40' W, 43 m, Santa Catarina; MZUSP 67576 (2, 108− 132 mm SL), 28o42' S, 48o46' W, 54−56 m, Santa Catarina; MZUSP 67631 (3, 106− 136 mm SL), 29o43' S, 49o55' W, 24 m deep, Rio Grande Do Sul; MZUSP 67683 (57), 30o47' S, 50o28' W, Rio Grande do Sul; MZUSP 67682 (1), 31o30' S, 51o00' W, Rio Grande do Sul; MZUSP 67676 (6), 33o32' S, 52o53' W, Rio Grande do Sul; MZUSP 67593 (2, 129,7− 132.1 mm SL), 34o34' S, 53o58' W, 22 m deep, Uruguay.