Ophidion zavalai Rotundo & Caires & Oliveira & Kuranaka & Figueiredo-Filho & Marceniuk 2023, new species

Ophidion zavalai new species

Figs. 1, 3, 5 and 6, Table 3

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Ophidion holbrookii (not of Putnam 1874) — Menezes & Figueiredo 1980: 47 (guide of fishes of southeastern Brazil; short description; first report from western South Atlantic)— Robins & Ray 1986: 99 (in part; assigned to Southeastern Brazil}— Smith 1997: 361 (in part; assigned to Southeastern Brazil)— McEachran & Fechhelm 1998: 748 (in part; assigned to Southeastern Brazil)— Nielsen et al. 1999: 41 (in part; FAO Fisheries Synopses; short description; illustration; occurrence in Southeastern Brazil)— Nielsen & Robins 2002: 972 (in part; reported to Southeastern Brazil)—Menezes & Figueiredo in Menezes et al. 2003: 59 (catalog of marine fishes of Brazil; listed)— Lea & Robins 2003: 7 (in part; assigned to Southeastern Brazil)— Zavala-Camin & Rotundo 2011: 3–10 (anatomy of the head lateral line and hearing system)— Britski & Figueiredo 2019: 204 (plate 004 from Burkhardt 1865–1866; Rio de Janeiro, Brazil; regarded as new species of “ Ophidium ”).

Doubtful references for this species

Ophidion cf. holbrookii — Garcia Jr. et al. 2010: 47; 2015: 51 (fishes of Bacia Potiguar, coast of Rio Grande do Norte; Brazil. Short description; photograph).

Holotype: MPEG 039113 (1, 271 mm SL, male), 24º14’59” S / 46º41’32” W, laje da Conceição, Itanhaém, São Paulo, Brazil

Paratypes: MPEG 039114 (1, 250 mm SL, female), laje da Conceição, Itanhaém, São Paulo, Brazil; NPM 6885 (2, 195 mm SL, male, 294 mm SL, female), 24º14’59” S / 46º41’32” W, laje da Conceição, Itanhaém, São Paulo, Brazil; MZUSP 125946 (2, 208 mm SL, female, 271 mm SL, male), 24º14’59” S / 46º41’32” W, laje da Conceição, Itanhaém, São Paulo, Brazil; AZUSC 6916 (1, 218 mm SL, female), 24º14’59” S / 46º41’32” W, laje da Conceição, Itanhaém, São Paulo, Brazil; ZUEC 17383 (2, 190 mm SL, female, 296 mm SL, male), 26º15’23” S / 48º01’58” W, barra de S„o Francisco, S„o Francisco do Sul, Santa Catarina, Brazil; LPB 31046 (2, 188 mm SL, female, 278 mm SL, male) 26º15’23” S / 48º01’58” W, barra de São Francisco, São Francisco do Sul, Santa Catarina, Brazil; AZUSC 6917 (1, 281 mm SL, male), 26º15’23” S / 48º01’58” W, barra de São Francisco, São Francisco do Sul, Santa Catarina, Brazil.

Non-type specimens: AZUSC 1616 (9, 250– 291 mm SL), 24º34’50” S / 46º39’01” W, Parcel Pedro II, Praia Grande, S„o Paulo, Brazil; AZUSC 1698 (5, 244– 285 mm SL), 25º15’45” S / 47º39’55” W, Ilha do Bom Abrigo, Cananéia, S „o Paulo, Brazil; AZUSC 6917.1 (15, 148– 217 mm SL, male), 26º15’23” S / 48º01’58” W, barra de São Francisco, S„o Francisco do Sul, Santa Catarina, Brazil; AZUSC 6685 (1, 255 mm SL), 26º38’16” S / 48º37’43” W, barra de Barra Velha, Barra Velha, Santa Catarina, Brazil.

Diagnosis. Ophidion zavalai n. sp. is distinguished from its western Atlantic congeners as follows: from O. antipholus by the rear of skull not outlined in dark pigment (Fig. 5) (vs. rear of skull broadly outlined in dark pigment); lacking a dark streak along the lateral line (vs. may have a dark streak along the lateral line, Fig. 5); from O. dromio by having 63–65 vertebrae, rarely 67 or 68 (vs. 67–69, Table 3); 14–16 caudal vertebrae (vs. 17, rarely 16, Table 3); from O. grayi by lacking irregular rows on body (vs. 2 irregular rows of dark brown spots, upper row from top of body to lateral line, lower row from lateral line down, Fig. 5); lacking dark brown spots on head and dorsal fin (vs. top of head and dorsal fin with scattered dark brown spots, Fig. 5); from O. guianense by rocker bone present (vs. absent, Fig. 6); 7.9–11.4 body height at center of the eye (vs. 13–14, Table 3); from O. josephi by having 107–135 dorsal-fin rays (vs. 138–146, Table 3), 88–107 anal-fin rays (vs. 114–121, Table 3), lacking dark spots on body (vs. 3 rows of dark spots along body, Fig. 5); from O. lagochila by having 2 upper gill rakers (vs. 3), rear of top of head not outlined in black (vs. outlined in black, Fig. 5), juvenile without a dark streak along the lateral line (vs. with a dark streak along the lateral line, Fig. 5); from O. marginatum by having 107–135 dorsal-fin rays (vs. 147–158, Table 3), 88–107 anal-fin rays (vs. 118–124, Table 3), body and lateral line without dark stripes (vs. with 2–3 dark stripes along its body and one at lateral line, Fig. 5); from O. puck by having 63–68 vertebrae (vs. 70, Table 3), 14–16 preanal vertebrae (vs. 17–18, Table 3); from O. robinsi by lacking dark brown spots (vs. with dark brown spots, Fig. 5); from O. selenops by having 88–107 anal-fin rays (vs. 123–129, Table 3), lacking a dark line along top of back before dorsal fin (vs. with a dark line along top of back before dorsal fin, Fig. 5); from O. holbrookii by caudal-fin length 0.7–2.8 (vs. 2.9–7.7, Table 3); postorbital length 8.4–11.2 (vs. 11.7–15.3, Table 3) in specimens less than 230 mm SL.

Description. Meristic and morphometric characters are shown in Table 3. Body moderately compressed, elongate with tapering tail. Head moderately broad, not depressed, bones firm in touch. Scales elongate, not overlapping, present on flanks and belly, 32 to 40 scales transversely across trunk above beginning of anal fin, 152 to 230 scales in transversal rows from pectoral base to caudal fin base. Pectoral fin pointed, shorter than postorbital distance; pelvic fin origin below anterior margin of orbit to mid-eye, longest ray not reaching pectoral fin base. Head without scales, except on predorsal region to supratemporal canal (about 27–41 predorsal scales). Anterior nostril a small tube over upper lip, posterior nostril slender, oval, over horizontal imaginary line through mid-eye. Snout rounded to slightly pointed, roughly equal to eye diameter. Eye large, oval, slightly elongated, lens well developed. Upper jaw ends just below mid-eye to posterior margin of orbit, rear upper jaw border partially covered by infraorbital regions in young specimens, exposed in adults; 3–4 rows of villiform teeth on jaws, larger on outer series, 3–4 rows of villiform teeth on vomer, palatines long with 3 rows of villiform teeth. Opercular and nasal spines absent. Upper branch of anterior gill arch with 2 knob–like rakers, lower branch with 4–7 short rakers. Head canals: supraorbital 2, infraorbital 3, supratemporal 4, preopercle to lower jaw 5.

Rocker bone with sickle to semicircular, half-doughnut shape, dorsal profile semicircular, ventral profile with anterior arm moderately long, slightly triangular to rounded, rear arm with ventral margin truncate to slightly indented. Concavity between arms gentle to semicircular, more so on largest specimens. Swimbladder carrot-like, pointed on rear portion, with two small, fringed anterior horns, sulcus present on ventral portion. Rocker bone abuts anterior portion of the bladder.

Color in life. Dark brown to tan on dorsum and flanks, whitish or light tan on belly, head tan, with whitish or silvery hue on opercle, eye lens dark, cornea dark brown with some golden hue. Pectoral fin dusky, pelvic fin whitish, dorsal and anal fins dusky with narrow black margin. Younger specimens pale or more yellow in ground color than adults.

Morphological variation. Significant developmental morphological variation was identified in two meristic and six morphometric characters in specimens ranging from 148 to 325 mm SL (Table 3). Smaller specimens have fewer dorsal-fin and anal-fin rays (Table 3); a shorter postorbital distance (Fig. 3e), a shorter outer and inner pelvic ray (Figs. 3f,g), shallower body at dorsal- and anal-fin origin (Figs. 3h,i), and a narrower interorbital distance. In addition, head shape and coloration vary between young and adult specimens (Fig. 5, see Color in life). Females exhibit a cylindrical gas bladder, posterior portion narrow, anterior portion with 2 small lateral chambers, this condition does not vary during ontogenetic development (Fig. 6), they also lack of rocker bone and parapophyses modifications that compose sonic apparatus (Fig. 6). Adult males present a posterior portion of gas bladder distended and narrow (Fig. 6), a differentiated chamber in anterior portion of gas bladder articulating with the reniform rocker bone (shape of a human kidney) (Fig. 6), and parapophyses modified at first neural spine (Fig. 6). n males, the rocker bone and parapophyses exhibit evident ontogenetic differentiation, being reduced at juvenile stages when the rocker bone is less evident in lateral view radiographs and differentiated from parapophyses which are clearly distinguishable (Fig. 6).

Sexual dimorphism. In a sample of 15 females (158–250 mm SL) and 35 males (148–296 mm SL), we observed a difference in the pattern related to dorsal outline between males and adult females (rectilinear and steeply inclined vs slightly rounded, Fig. 5). Examinations of gas bladder and x-ray reveal that males possess a rocker bone and modifications to the anterior vertebral parapophyses (Fig. 6).

Distribution and habitat. Ophidion zavalai is found on soft bottom associated coastal marine habitats. It occurs in the western South Atlantic, off the eastern to southeastern coast of Brazil (Fig. 4),

Etymology. The new species is named in honor of Dr. Luis Alberto Zavala-Camin, researcher at the Instituto de Pesca, S„o Paulo, Brazil, and professor at the Universidade Santa Cecília in Santos, Brazil, for his great contribution to the knowledge of marine fishes in Brazil.

Remarks. The description of O. zavalai is based on the knowledge and account of variation associated with ontogenetic and sexual development, yet not described for gas bladder and sonic apparatus (Lea & Robins 2003). Also, structures used by males for sound production and display for females (Rose 1961; Marshal 1967; Courtenay 1971; Parmentier et al. 2006; Nguyen et al. 2008; Zavala-Camin & Rotundo 2011) are likely important in species recognition. The gap observed between the distribution of O. holbrookii and O. zavalai (Fig. 4) is supported by an extensive search of zoological collections and literature of the northeastern coast of Brazil. Material from Brazilian collections (Universidade Federal da Paraíba; Universidade Federal de Alagoas) regarding Ophidion were either based on identifications or specimens deposited were too small to be properly identified. Personal communication with colleagues (Dr. Claudio Sampaio, UFAL) support absence of these taxa from northeastern Brazil. Also, there is no mention of this species taxa in most of the known literature for the region (Eskinazi 1972; Araújo et al. 2004; Nobrega et al. 2009).A presumable report of Ophidion (as Ophidion cf. holbrookii) from Northeastern Brazil (Bacia Potiguar) has been made by Garcia Jr. et al. (2010, 2015), but regardless of the similarity of specimen depicted to O. zavalai, the description is rather short and with no meristic data, and material of this specimen is not available. Specimens from this area previously identified as O. holbrookii (MNHN 00005772) were found to be Lepophidium. Thus, the occurrence of Ophidion holbrookii and O. zavalai in northeastern Brazil has yet to be confirmed.