Serranus fusculus ( Poey, 1861 )

Carvalho-Filho, Alfredo, Baldwin, Carole C., Fischer, Luciano G., Robertson, D. Ross, Bertoncini, Athila, Garcia, Lucas Canes, Silva, Jodir Pereira Da & Sampaio, Claudio L. S., 2023, Generic reassignment of Centropristis fuscula Poey, 1861 (Teleostei: Serranidae), with re-description of the species and comments on its geographical range and sexual system, Zootaxa 5346 (1), pp. 51-73 : 54-63

Redescription of Serranus fusculus ( Poey, 1861)

( Figs. 2–4 ; Table 1 )

Twospot Sea Bass (English); Serrano, Serrano olivaceo (Spanish); Michole de fundo; Jacundá (Brazilian Portuguese) Centropristes fusculus, Poey, 1861: 342–343 ; Bortone 1977; Vandersea et al. 2008. Haliperca fusculus, Poey, 1868 . Haliperca fuscula, Poey, 1875: 22 ; Poey 2000: 97, lámina 55, fig. 1. Serranus fusculus , Jordan, 1887: 579; Jordan & Eigenmann 1890: 407; Claro 1994: 55–70. Prionodes fusculus , Jordan & Evermann,1896: 1211; Guitart 1979: 39–40. Centropristes fusculus, Howell Rivero, 1938 ; Robins & Starck 1961; Bortone 1977.

Centropristis fuscula, Breder & Rosen, 1966: 656–657 ; Robins & Ray 1986: 138; Robins et al. 1991: 45; Eschmeyer 1998: 622; Claro & Parenti 2001: 45; Heemstra et al. 2002; Nelson et al. 2004: 126; Richards et al. 2006: 1226; Weaver et al 2006: 67; Bertoncini 2007: 11 (pictures of species inverted); Bowling 2012.

Serranus atrobranchus, Figueiredo & Menezes, 1980: 32 , 78; Figueiredo et al. 2002: 171; Bernardes et al. 2005: 218.

Holotype: MCZ 10015, 141 mm SL, Havana, Cuba, collected by Felipe Poey, 1864; identified by W.N. Eschmeyer.

Non-type specimens (60): United States specimens (7): UF 44997 (3 preserved, 51.0–115.5 mm SL, 1 cleared/ stained), 33°15′59.8″N 77°12′59.8″W, off Cape Fear , North Carolina , USA, 98.7 m, col. E.P. Epperly, 9 Jul. 1982; UF 98613, 113.3 mm SL, 24°23′28.0″N, 82°11′51.7″W, S of Marquesas Key, Florida , USA, 112–121 m, col. G.H. Burgess, F.F. Snelson, M. Johnson, 26 Sep. 1992; UF 100391, 166.4 mm SL, hermaphrodite, 32°46′59.9″N, 78°10′59.9″W, SE of Georgetown , South Carolina , USA, 164.5 m, col. F/ V Miss Olive, 15 Jul. 1995; UF 180319 , 35.4 mm SL, 24°55′25.7″N, 80°37′40.8″W, off Islamorada, Florida , USA, col. M/ V Queen of Nassau , 3 Jun. 2009. Caribbean specimens (8): USNM 407616, 153.1 mm SL, 16°06′45.9″N, 86°16′05.9″W , Honduras, trawl, 204–248 m, col. D. R. Robertson , C.I. Castillo, B/O Miguel Oliver, Cruise for OSPESCA (Organización del Sector Pesquero y Acuícola del Istmo Centroamericano), 24 Jan. 2011; USNM 407807, 139.8 mm SL , same data as above; USNM 407811, 130 mm SL , same data as above; USNM 407812, 155.2 mm SL , same data as above; USNM 413784 , 60 mm SL, 12°04′59.5″N, 68°53′56.8″W, off Substation Curaçao, Curaçao, vessel Curasub, 123–160 m, col. A. Schrier, B. Brandt, C. Baldwin, A. Driskell, P. Mace, 10Aug. 2012; USNM 438670, 164.8 mm SL, 15°36′07.6″N, 61°28′14.5″W, near Portsmouth, Toucari , Dominica, vessel Curasub, 259 m, col. A. Schrier, C. Castillo, B. Van Bebber, P. Rjiskamp, Deep Reef Observation Project ( DROP), 3 May 2016; USNM 433449 , 94 mm SL, 12°04′58.8″N, 68°53′56.4″W east of Substation Curaçao, Curaçao, vessel Curasub, 241.7 m, col. C. Baldwin, C. Castillo, B. Van Bebber, 8 Dec. 2014; USNM 414810 , 89.2 mm SL, 12°04′59.5″N, 68°53′56.8″W, east of Substation Curaçao, Curaçao, vessel Curasub, 87–209 m, col. B. Brandt, B. Van Bebber, C. Baldwin, 15 Aug. 2012. Brazilian specimens (42): AZUSC 5962, 159.3 mm SL, off Camaçari / Arembepe , Bahia , Brazil, hook and line, 250–350 m, col. G. Harfush, Jul. 2008; CIUFESUFES 580 (2, 151.3–159.8 mm SL, 20°28′50″S, 39°52′35″W, Barranco, Vitória , Espírito Santo , Brazil, col. A.C.A. Santos, J.L.Gasparini, 10 Jun. 2003; LABIPE 2263, 127.9 mm SL, Bacia Potiguar, off Natal , Rio Grande do Norte , Brazil, bottom trawl, 145 m, 22 May 2011; LABIPE 2266, 137 mm SL, Bacia Potiguar, off Natal , Rio Grande do Norte , Brazil, bottom trawl, 145 m, 22 May 2011; MNRJ 42165 (2, 175.9–176.1 mm SL), 23º50′S, 42º50′W, off Rio de Janeiro , Brazil, 180–220 m, rocky bottom, col. D.F.Moraes, A.Galv „o, R.Galv„o, 6 Jun. 2013; MNRJ 45300, 149.2 mm SL, 23º41′S, 42º52′W, off Rio de Janeiro , Brazil, 123 m, col. D.F.Moraes Jr., R. Soares, R. Bordatur, 28 Mar. 2015; MNRJ 47081 (2, 150.6–160.6 mm SL), 23º50′S, 42º50′W, off Rio de Janeiro , Brazil, 225 m, col. D.F.Moraes Jr. 18 Apr. 2008; MNRJ 50678, 158.8 mm SL, 23º30′01″S, 42º33′52″W, off Rio de Janeiro , Brazil, 123 m, col. D.F.Moraes Jr., 22 May 2008; MZUSP 71057 , 98.7 mm SL, 22°44′S, 40°40′W, off Espírito Santo , Brazil, R / V Prof. W. Besnard, station 2206, bottom trawl, 180 m, 20 Feb. 1975; MZUSP 71079, 129.7 mm SL, off Rio Grande do Sul , Brazil, R / V Prof. W. Besnard, col. DZSP-IOUSP, 14–30 Aug. 1968; MZUSP 71081, 129.7 mm SL, 34°03′33″S, 51°50′00″W, off Rio Grande do Sul , Brazil, R / V Prof. W. Besnard, station 569, 96 m*, 12 Mar. 1969; MZUSP 86517 , 53.4 mm SL, 24°13′52″S, 44°16′49″W, off Rio de Janeiro , Brazil, R / V Soloncy Moura, REVIZEE SCORE Sul, station 1137, bottom trawl, 150 m, 22 Apr. 2002; MZUSP 86518, 131.9 mm SL (with oocytes and tests), 23°36′02″S, 42°17′31″W, off Rio de Janeiro , Brazil, R / V Soloncy Moura, REVIZEE SCORE Sul, station 602, bottom trawl, 161 m, 26 Jun. 2002; MZUSP 86519, 104.6 mm SL, 23°35′54″S, 42°17′13″W, off Rio de Janeiro , Brazil, R / V Soloncy Moura, REVIZEE SCORE Sul, station 1251, bottom trawl, 162 m, 27 Apr. 2002; MZUSP 86520 (3, 110.3–124.8 mm SL), 24°49′04″S, 44°40′29″W, off São Paulo , Brazil, R / V Soloncy Moura, REVIZEE SCORE Sul, station 534, bottom trawl, 206 m, 21 Oct. 2001; MZUSP 71080 (2, 137.2–140 mm SL), 30°30′0.00″S, 48°43′59.88″W, off Rio Grande do Sul , Brazil, R / V Prof. W. Besnard, station 541, bottom trawl, 195 m, 6 Mar. 1969; MZUSP 71060 (3, 115.1–154.8 mm SL), 29°55′59.88″S, 49°25′0.12″W, off Rio Grande do Sul , Brazil, R / V Prof. W. Besnard, station 435, 67–83 m, 4 Dec. 1968; MZUSP 71061, 148.2 mm SL, 31°01′59.9″S, 49°37′00.1″W, off Rio Grande do Sul , Brazil, R / V Prof. W. Besnard, station 300, 154 m, 23 Jun. 1968; MZUSP 71077 , 96.3 mm SL, 23°30′0.00″S, 42°27′0.00″W, off Rio de Janeiro , Brazil, R / V Prof. W. Besnard, station 1147, 134 m, 8 Aug. 1970; MZUSP 49001 (2, 74–109.8 mm SL), 30°36′00.0″S, 48°20′60.0″W, off Rio Grande do Sul , Brazil, 157 m, Projeto Talude 486 # 4, bottom trawl, 157 m, col. M. Haimovici, 20 Jul. 1986; MZUSP 71076 , 84.9 mm SL, 24°13′00.0″S 44°23′00.0″W, off São Paulo , Brazil, R / V Prof. W. Besnard, station 1021, bottom trawl, 145 m, 27 May 1970; MZUSP 80770 , 22.1 mm SL (juvenile), 29°29′47.0″S 48°06′41.0″W, off Santa Catarina , Brazil, R / V Atlântico Sul , REVIZEE SCORE Sul —station 373, midwater trawl (130 m), local depth 246 m, col. Equipe REVIZEE, 10 Dec. 1997; MZUSP 78287 , 17 mm SL (larva), 30°36′00″S, 48°21′00″W, off Rio Grande do Sul , Brazil, R / V Atlântico Sul — REVIZEE SCORE Sul —station 378, midwater trawl (75 m), local depth 980 m, col. Equipe REVIZEE, 11 Dec. 1997; MZUSP 80767 , 23 mm SL (juvenile), 27°33′41.0″S 47°25′30.0″W, off Santa Catarina , Brazil, R / V Atlântico Sul — REVIZEE SCORE Sul —station 357, midwater trawl (30 m), local depth 159 m, col. Equipe REVIZEE, 3 Dec. 1997; MZUSP 78185 , 23 mm SL (juvenile), 28°23′27.0″S 48°08′47.0″W, off Santa Catarina , Brazil, R / V Atlântico Sul — REVIZEE SCORE Sul —station 366, midwater trawl (30 m), local depth 102 m, col. Equipe REVIZEE, 8 Dec. 1997; MZUSP 71058, 127.9 mm SL, −30.066668, −50.049999, R / V Prof. W. Besnard , station 298, 27 m (questionable depth, see results), col. DZSP-IOUSP, 22 Jun. 1968; MZUSP 71059 , 25 mm SL (juvenile), 30°10′00.0″S 48°58′00.0″W, off Rio Grande do Sul , Brazil, R / V Prof. W. Besnard, station 1691, bottom trawl, 132 m, col. G.Q. Benvegnú, 29 Jan. 1972; MZUSP 80769 , 16 mm SL (larva), 33°00′37.80″S, 50°14′00.59″W, off Rio Grande do Sul , Brazil, R / V Atlântico Sul , REVIZEE SCORE Sul —station 208, midwater trawl (100 m), local depth 750 m, col. Equipe REVIZEE, 1 May 1997; MZUSP 80768 , 10.5 mm SL (larva), 28°51′43.19″S, 47°10′08.39″W, off Santa Catarina , Brazil, R / V Atlântico Sul , REVIZEE SCORE Sul —station 368, midwater trawl (50 m), local depth 1105 m, col. Equipe REVIZEE, 8 Dec. 1997; NPM 10150 (2, 78.7–80.2 mm SL), 20°41′47″S, 40°02′09″W, off Espírito Santo , Brazil, Projeto Habitat, R / V Gyre, bottom trawl, 76.3–87.4 m, col. P. Costa et al., 22 Apr. 2008; NPM 2134, 134 mm SL, 30°51′00.00″S, 49°16′59.98″W, off Rio Grande do Sul , Brazil, R / V Atlântico Sul , Projeto Talude, leg 3/87, station #18, bottom trawl, 186 m, col. M. Haimovici, 21 Mar. 1987; NPM 2458, 125 mm SL, 34°01′59.98″S, 51°32′59.99″W, off Rio Grande do Sul , Brazil, R / V Atlântico Sul , Projeto Talude, leg 3/87, station #7, bottom trawl, 150 m, col. M. Haimovici, 16 Mar. 1987; NPM 3564, 123 mm SL, 31°08′59.99″S, 49°32′59.99″W, off Rio Grande do Sul , Brazil, R / V Atlântico Sul , Projeto Talude, leg 3/87, station #16, bottom trawl, 188 m, col. M. Haimovici, 20 Mar. 1987; NPM 6366, 147 mm SL, 34°21′00″S, 51°42′00″W, off Rio Grande do Sul , Brazil, R / V Atlântico Sul , Projeto Talude, leg 3/87, station #5, bottom trawl, 233 m, col. M. Haimovici, 16 Mar. 1987. Uruguayan specimens (3): MZUSP 71078 (3, 84.7–104 mm SL), 33°52′59.88″S, 52°22′59.88″W, off Uruguay, R / V Prof. W. Besnard, station 407, 18 m (questionable depth, see results), 30 Oct. 1968 .

Note: all MZUSP specimens were labeled as Serranus atrobranchus .

Diagnosis: Serranus fusculus is distinguished from its congeners by the following combination of characters: caudal-fin branched rays 9 + 8; total gill rakers 18–21; pectoral rays 18, rarely 17; lateral line usually with 46–48 pored scales; scales around caudal peduncle 30 or 31, cheek scales 5 or 6; large teeth on both jaws; color pattern: yellowish, tan, olivaceous or light brown overall, with about six faint dark vertical cross bands (fainter below lateral line, first three slightly diagonal); two dark round to oval spots, conspicuous one at center of band that crosses caudal-fin base and second, more diffuse spot on third band behind head, under end of spinous dorsal fin; black, vertically lanceolate blotch under opercle, often not or scarcely visible externally; fins pale with yellow to green tints. Specific differences are enumerated in Comparisons.

Description. Proportional measurements and counts of the holotype and additional specimens from United States of America, the Caribbean, and Brazil are given in Table 1 ; some body proportions are slightly different between Brazilian and American/Caribbean specimens. Dorsal-fin rays X, 12, rarely 11; anal-fin rays III, 7; pectoral-fin rays 18, rarely 17 (four of 55 specimens examined); pelvic-fin rays I, 5; principal caudal-fin rays 17, all branched (9+8), lowermost usually split at base, upper part branched, lower entire; occasionally uppermost ray (in one of 6 fishes examined with X-rays) is split, lower part branched, upper entire; lateral-line scales usually 46–48 (in 40 of 47 specimens examined, three with 49, two with 50, one with 51, one with 45); scales above lateral line to origin of dorsal fin 4; scales below lateral line to origin of anal fin 12; scales around caudal peduncle 30 or 31; cheek scales 5–6, in 6–8 vertical/diagonal series; gill rakers, including rudiments, 18–21, rarely 22; branchiostegal rays 7; vertebrae 24 (X-rays of six specimens examined).

Body elongate, head sub-conical; mouth moderate, slightly oblique; maxilla reaching almost to vertical through middle of pupil. Upper jaw with band of minute teeth mixed with 2–3 large canines at symphysis, followed by outer row of very large, canine-like, pointed, stout, separated teeth (some curved backwards), and inner row of much smaller canine-like teeth, both sets followed by band of villiform teeth; lower jaw with band of minute teeth, few large teeth at symphysis, followed by outer row of very large teeth as in upper jaw, inner row of very small and sparse canine-like teeth, without villiform-teeth band posteriorly; villiform-teeth band on vomer and palatines, both mixed with 1–3 much larger canine-like teeth often curved backwards; tongue lanceolate, smooth, tip bluntly pointed, its base much wider. Gill rakers 18–21, moderate to short, not flexible, longest at first gill arch, about 25–30% of eye diameter. Nostrils before center of eye, not very close to one another; anterior nostril in very short tube with large lanceolate to heart-shaped flap posteriorly that, when deflected, reaches about half internarial distance; posterior nostril wide open, lacking raised rim. Smooth area on top of cranium large, long; supraoccipital crest low, short, not extending backwards to posterior border of cranium, which is nearly vertical in lateral profile.

Opercle with three flat spines, upper one poorly developed, central one straight, larger, and more conspicuous than lower; opercular membrane rounded at distal end. Preopercle profusely serrate on both limbs, serrae somewhat larger at angle. Preorbital narrow, about 25–33% of pupil diameter.

Lateral line slightly arched over pectoral-fin area, parallel to dorsal body profile from that point to caudal peduncle, where bends to middle of body and is straight to caudal-fin base. Scales ctenoid, firmly attached to skin; interorbital space, snout, preorbitals, jaws, chin, throat, and branchiostegal membranes naked; scales on top of head reaching anteriorly to between level of posterior border of eye or almost to middle of orbit (as in holotype and two other specimens examined: MZUSP 71060, 115 and 132 mm SL), arranged in 5–7 horizontal series followed by 11–15 transverse series of larger scales, from interorbital to dorsal-fin origin; cheek scales 5–6, in 6–8 vertical/ diagonal series, plus incomplete series posteriorly and/or anteriorly; interopercle smooth-edged, with ctenoid scales; no scales on fin membranes or basally on dorsal and anal fins; pectoral fin with scales only on base; pelvic fin with minute scales along inner one-third to half of rays.

Dorsal-fin origin slightly behind pectoral-fin base and fourth or fifth lateral-line scale; spiny portion incised; first spine about ¾ length of second; spines increasing in length through fifth spine, with fourth spine longest in holotype and seven other specimens, remaining spines decreasing in length, tenth about half length of fifth; dorsal-fin rays branched; posterior tips of soft dorsal and anal fins not reaching caudal-fin base when depressed. Anal-fin origin approximately below first to third dorsal-fin ray, just after dark blotch on mid-flank; first anal-fin spine about half length of second, which is stouter than, and slightly shorter or equal to, third. Caudal fin emarginated to forked, upper lobe slightly longer. Pectoral fin almost reaching vertical through anus, all rays branched except uppermost, eighth or ninth uppermost ray longest. Pelvic-fin origin slightly ahead of pectoral-fin base, posterior tip not reaching anus. Maximum known length 176.1 mm SL (MNRJ 42165).

Sagittal otolith has fusiform shape, sinuate margins, and slightly curved profile with moderate thickness ( Fig. 5 ). Sulcus acusticus well-marked, vertically positioned in median portion of otolith and presenting ostial opening, that is, ostium opens widely in anterior margin of otolith, and with cauda distinctly closed far away from posterior margin. Ostium narrow, elongated, shorter than cauda, which is straight with flexed end. Rostrum long and antirostrum short to absent. Dorsal area of otolith has elongated groove and well-developed narrow crista superior. Ventral area has broad crista inferior. Inner surface of otolith irregular without concretions. Sagitta similar to that of other Serranus species, especially S. hepatus ( Tuset et al. 2008) , but also similar to that of Centropristis species ( Bortone 1977).

Size: The largest adults collected were a 175 mm SL individual taken by submarine in the Caribbean ( USNM 438670 , from Dominica, collected at 259 m deep, now measuring 164.8 mm SL, probably a result of shrinkage in formalin after preservation) and a 176 mm SL fish collected by bottom trawl in Brazil ( MNRJ 42165 , from Rio de Janeiro, collected at 180–220 m deep). The smallest benthic-stage fish taken by submersible in the Caribbean was 35 mm SL, and a 25 mm SL individual was collected by bottom trawl in Brazil. Similarly sized fish were collected by midwater trawls, suggesting that the 25-mm fish from Brazil could have been taken in midwater as the bottom trawl was being deployed or retrieved. The length-weight relationship (TW=a× TLb; a=linear coefficient related to body shape; b=angular or allometric coefficient; TW= Total Weight, TL = Total Length ) obtained from 28 fresh specimens from the southwestern Atlantic (74–200 mm TL and 5.2–105 g TW) was: TW=0.00001TL 3.048 8, R 2 =0.9915.

Color pattern of live specimens: Body background varying from tan to pinkish white to light grey; seven (occasionally six) indistinct orangish to reddish to brownish crossbands between head and caudal fin, varying in width and sometimes merged, first four slightly diagonal, last 2–3 vertical: first beginning immediately behind head, running to pectoral-fin base; second from spinous dorsal-fin origin to below midbody; third from end of spinous dorsal fin to below midbody; fourth, thinner, from mid-base of soft dorsal fin to below midbody; fifth from rear end of soft dorsal-fin base almost to anal-fin base; sixth, thinnest, often indistinct, through mid-caudal peduncle; seventh at caudal fin base; third and last bars with conspicuous black blotch at midbody, anterior blotch irregular, subquadrate, posterior blotch oval to rounded or somewhat oblong. Upper portion of head to about middle of snout with elongated streaks colored as body bars; lower portion of head and belly conspicuously white, often with silver hue; cheeks with faint, diagonal reddish to golden bar from lower edge of eye to operculum lower corner. Black to greenish usually triangular blotch under preopercle, often observed externally as smudge, or irregular blotch, particularly in live fish ( Fig. 4A–C ). Pectoral, pelvic, and anal fins light yellow to white; spinous dorsal fin with upper third yellow, translucent below; soft dorsal-fin rays yellowish to lemon to whitish, their membranes translucent; caudal fin translucent to whitish, base usually darker; pupil greenish, encircled by thin golden ring. Older/larger fishes often with upper lip, and dorsal and caudal fins, yellow. Young with black body spots more conspicuous, body bars usually present with hues of electric blue, gold and silver sometimes present on dorsum and head.

Color pattern of preserved specimens: Tan to brownish overall, lower portion of head and belly whitish, two dark blotches on body midline present, dark body bars less distinct, mainly in juveniles; fins unmarked; dark preopercular blotch often visible.

Distribution: Serranus fusculus occurs from North Carolina ( USA) to northern Cuba, on the east, northwest and southern Caribbean ( Dominica, Honduras, Curaçao), to southern Brazil and Uruguay. Most specimens were collected with bottom trawls between depths of 80–300 m on gravel, rubble, and rocky bottoms, but juveniles and larva were also collected with midwater trawls between 30– 130 m. The body-length distribution in relation to the depth of collection ( Fig. 1 ) shows a tendency for larger specimens to occur in deeper waters. This effect, called “bigger-deeper” ( Macpherson 1979; Macpherson & Duarte 1991; Massutí et al. 2004; Moranta et al. 2004), and also known as “Heincke’s law,” ( Heincke 1913; Cushing 1975) occurs in various species due to ontogenetic displacement to deeper waters. The occurrence of larvae and juveniles up to 25 mm SL in the water column near the surface over deep water suggests that individuals under ~ 25 mm SL are pelagic, and that they settle at the bottom at about 25 mm SL. Although the smallest fish (n = 4) collected with bottom trawls in Brazil were ~ 40 mm SL, several benthic individuals of 35 mm SL were collected by submersible at Curaçao. The species is not common in the North Atlantic, despite Poey’s (2000: 98) statement that “no es raro”—i.e., “it is not rare,” but it has often been collected in deep-sea trawling from northeastern to southern Brazil, where it apparently is more abundant ( Weaver et al. 2006; Bernardes et al. 2005; Lins Oliveira et al. 2015; this work).

Habitat: Adults of the study species have been collected or observed by submarine in the Caribbean at depths between 76 and 308 m. We regard the two shallow records (17–23 m) from Uruguay as unreliable, as depth was not recorded during either collection, and those depths are inferred from georeferenced coordinates and could be erroneous. Adults are known from rocky and rubble bottoms. Settlement of pelagic juveniles into benthic habitats apparently occurs at about 25 mm SL.

Sexual system: Robins & Starck (1961) noted that the holotype of Centropristis fuscula from Cuba was a male. We visually examined the gonads of one specimen from South Carolina ( USA, UF 100391, hermaphrodite) and 20 specimens from Brazil (AZUSC 5962: “almost-female”; MZUSP 49001, 71057, 71060, 71076, 71079, 71080, 71081, 86518, 86519, and 86520: all simultaneous hermaphrodites; MZUSP 71061 and 71077: “almost-females”; and MZUSP 71058: “almost-male”); of these, we found one “almost-male,” seventeen synchronous hermaphrodites in which the amount of ovarian tissue exceeded that of testicular tissue, and three “almost-females” with very little testicular tissue and much more ovarian tissue than in the hermaphrodites. Histological analyses were done using gonads of 14 specimens ( Table 2 , Figs. 6–7 ). The gonadal and cellular structures of the testicular and ovarian portion seem to be like those of other hermaphroditic serranids studied so far, including S. annularis , S. phoebe , and S. tabacarius ( Petersen 1995) . In contrast to other serranid species, where protogyny is generally observed, testes and ovaries in Serranus fusculus develop synchronously ( Fig. 7 ). These data indicate that this species has a simultaneous hermaphrodite sexual system and there is no evidence of androdioecy, which occurs in two species of Serranus ( S. baldwini and S. psittacinus ), in which small hermaphrodites coexist with large males and the latter are produced by loss of female function in hermaphrodites ( Pannell 2002). Another important consideration to be made is that, although few specimens (only 14) of Serranus fusculus were analyzed, we found specimens in full reproductive activity, including the presence of post-ovulatory follicles (POF), which are temporary ovarian structures indicative of spawning. Even in works that collected and analyzed a greater number of fresh specimens of Serranus spp. , the presence of post-ovulatory follicles was relatively rare ( Neves et al. 2014, Alós et al. 2013). This may indicate intense reproductive activity for the species.

After examining the anatomy of the gonads of an “almost-female” fish (AZUSC 5962), it was discovered that: “The anterior part of both gonads presents an almost rigid tunic tissue with tubular formations which dissipate at the anterior quarter of the gonads, posterior to which they are replaced by ovocytic lamellae. This structure suggests a plesiomorphic character of a male or hermaphrodite becoming a female” (M. Rotundo, curator of the AZUSC ichthyology collection, pers. comm.). This “almost-female” is the third largest fish (159.3 mm SL) examined by us. The Brazilian “almost-male” measured 127.9 mm SL. Those we call pure hermaphrodites span the rest of the range of sizes down to the smallest fish, and the “almost-females” are among the larger fishes (96.3–148.2 mm SL). Future investigations will be needed to clarify the matter.

Figures

FIGURE 1. Linear correlation between depth of collection and size of Serranus fusculus. Gray dots denote specimens identified as post-larvae or juveniles.

FIGURE 2. Serranus fusculus illustration by Lucas Canes Garcia

FIGURE 3. Serranus fusculus, live specimen, approximately 140 mm SL, Curacao, August 2013. Image by D. Ross Robertson & Carole Baldwin

FIGURE 4. Serranus fusculus. A) AZUSC 5962, 159 mm SL, female, Bahia, Brazil, 2008; B) fresh specimen, off Rio Grande do Sul, Brazil, pictured in Bernardes et al., 2005; C) fresh specimen, off Natal, Rio Grande do Norte, Brazil, stationARMT53B, pictured in Lins Oliveira et al., 2015; D) Holotype, MCZ 10015, male, 141 mm SL, Havana, Cuba,1864. E) Radiograph, NPM 2458, 125 mm SL, off Rio Grande do Sul, Brazil, depth 186 m. Images by Sampaio, C.L.S. (A); Fischer, L.G. (B, C, E); Museum of Comparative Zoology, Harvard University © President and Fellows of Harvard College (D).

FIGURE 5. Otoliths from right side of Serranus fusculus with 200 mm TL, 188 mm FL, and 105 g TW in superior (A), inner (B), and outer view (C). TW=total weight, TL=total length, FL=fork length.

FIGURE 6. Photos of the mature testicular portion (full of spermatozoa) of the ovotestes specimen MZUSP 71061 (left) and the ovarian portion of specimen NPM6366 (right) containing a post-ovulatory follicle (POF). Staining: HE. Scale bar=150 μm.

FIGURE 7. Histological section of specimen MZUSP 71061, in which the synchronous development of testicular (1) portions, containing spermatozoa in the spermatic duct, and ovarian (2) portions, containing oocytes at an advanced stage of development, can be observed. Staining: HE. Scale bar=150 μm.