Mugil curvidens Valenciennes, 1836

Menezes, Naércio A., Nirchio, Mauro, Oliveira, Cláudio De & Siccharamirez, Raquel, 2015, Taxonomic review of the species of Mugil (Teleostei: Perciformes: Mugilidae) from the Atlantic South Caribbean and South America, with integration of morphological, cytogenetic and molecular data, Zootaxa 3918 (1), pp. 1-38 : 21-23

Mugil curvidens Valenciennes, 1836

( Fig. 7 )

Mugil curvidens Valenciennes, 1836: 149 , pl. 314 (type locality: Ascension Island, South Atlantic; Bahia, Brazil); syntypes: MNHN A-3626 (5), Bahia (examined); A-3646 (3) Ascension Island; Hureau, 1972: 690 (type catalog); Menezes, 1983: 2 (only specimens originating from northern to eastern Brazil); Menezes & Figueiredo,1985: 22 (only specimens originating from northern to eastern Brazilian coast); Cervigón, 1992: 362 (northern coast of South America); Thomson, 1997: 489 (only specimens originating from Ascension Island and Bahia; description); Gasparini & Floeter, 2001: 1643 (Trindade Island); Harrison, 2003: 1081 (only specimens originating from Ascension Island and northern to eastern Brazilian coast (size, habitat, biology and fisheries; distribution); Menezes et al., 2003: 65 (only specimens originating from northern to eastern Brazilian coast).

Material examined. MNHN 2012-0400, SL 69.9 mm, herein designated as lectotype; MNHN A- 3226, 4, 57.5–60.1 mm, herein designated as paralectotypes; MZUSP 115080, 3, SL 54–87 mm, Brazil, Pará: Marapanim, 0°42’S, 47°42’W; MZUSP 115081, 4, SL 27–57 mm, Rio Grande do Norte: Ponta do Morcego, 5°47’S, 35°11’W; MZUSP 115083, 2, SL 35 and 38 mm, Pernambuco: Ponta de Pedras 7°37’32.6”S, 34°48’51.5”W; MZUSP 42030, 1, SL 148 mm: Coqueiro Seco, Canal do Cadajós, 9°24’54.7”S, 35°31’16.5”W; MZUSP 103994, 1, SL 191 mm SL, Barra de Santo Antônio, 9°24’16.8”S, 35°31’47”W; MZUSP 67449, 5, SL 147–196 mm, Lagoa Mundaú, 9°38’35.5”S, 35°46’44”W; MZUSP 67454, 1, 121 mm, Sergipe: Rio Sergipe, 10°51’49.8”S, 37°01’53”W; MZUSP 67448, 16, SL 45–96 mm, Bahia: Ilha de Itaparica, Rio Penha, 13°00’50”S, 38°44’01”W; MZUSP 67456, 10, SL 40–69 mm, Arembepe, 12° 45’47”S, 38°10’40”W; MZUSP 67450, 67451, 3, SL 97–138 mm, Salvador, Itapuã, 12°56’48”S, 38°22’28”W; MZUSP 67459, 3, SL 37–50 mm, Ilha de Itaparica, Mar Grande, 12°59’30.5”S, 38°41’25”W; MZUSP 67522, 1, SL 79 mm, Ilha de Itaparica, 13°00’S, 38°44’W; MZUSP 67465, 1, SL 73 mm, Ilhéus, 14°47’45.5”S, 39°02’77”W; MZUSP 60505, 5, SL 25–53 mm, Arquipélago dos Abrolhos, Ilha Siriba, 17°55’34”S, 38°56’07”W; MZUSP 114039, 8, SL 128–197 mm, Baía de Todos os Santos, Praia de Boa Viagem, 12° 56’06”S, 38°30’35.5”W; MZUSP 115082, 2, SL 41 and 42 mm, Espírito Santo: Guarapari, Praia dos Namorados, 20°40’12”S, 40°29’43”W; MZUSP 115085,1, SL 77 mm, Rio de Janeiro: Atafona, Ilha do Lima, 21°36’S, 41°01’W; MZUSP 115085,1, SL 60 mm, Atafona, Pontal, 21°06’33”S, 41°06’06”W; MZUSP 115086, 2, SL 31 and 34 mm, 21°30’S, 41°01’W; MNRJ 2977, 8, SL 32–36 mm, Baía de Guanabara, approximately 22° 48’43”S, 43°08’44”W.

Diagnosis. Mugil curvidens differs from congeners collected in the study area by the presence of conspicuously curved teeth on upper jaw (vs. teeth slightly curved on upper jaw) and from other species except M. trichodon and M. liza in having an anal fin with 3 spines and 8 branched rays in adults or 2 spines, 1 unbranched ray and 8 branched rays in juveniles (vs. 3 spines and 9–10 branched rays or 2 spines, 1 unbranched ray and 9–10 branched rays). Mugil curvidens is distinguished from M. trichodon by the presence of 1 unbranched ray and 8 branched rays in the second (soft) dorsal fin in adults or 2 unbranched and 7 branched rays in juveniles (vs. 1 unbranched ray and 7 branched rays in adults or 2 unbranched rays and 6 branched rays in juveniles) and from M. liza in having the second dorsal and the anal fins scaled except for their distal portions (vs. second dorsal and anal fins with the scales restricted to an anterior basal portion and a single posterior row of scales sometimes incomplete).

Description. Morphometric data presented in Table 9 . Maximum examined body length 197 mm SL. Body elongate, compressed, moderately deep compared to congeners. Greatest body depth at vertical through spinous dorsal-fin origin. Dorsal profile of head and body convex from tip of snout to caudal peduncle, straight to slightly concave along caudal peduncle. Ventral profile of head and body convex from tip of lower jaw to anal-fin origin, slightly concave above caudal peduncle. Orbital diameter greater than snout length. Eye covered with adipose tissue, except for narrow oval-shaped central area in adults. Adipose tissue almost absent in specimens smaller than 30–35 mm SL.

Anterior spinous dorsal fin with 4 slender spines connected by membrane, n = 96. Spinous dorsal fin-origin about midway between snout tip and caudal-fin base. Posterior soft dorsal-fin rays ii,7, n = 24 in specimens smaller than 30–35 mm SL, i, 8 in adults, n = 72. Unbranched pectoral-fin rays ii, first ray much smaller than second; branched rays 13–15, 14, n = 96. Tip of pectoral fin falling short of spinous dorsal-fin origin; extending to vertical through about middle of pelvic fin. Pelvic fin I,5. Tip of pelvic reaching vertical through base of first or second dorsal-fin spine. Anal fin with II,i, 8 in specimens smaller than 30–35 mm SL; III, 8 in adults, n = 96.

Mouth subterminal. Tip of maxilla extending slightly beyond vertical through anterior border of orbit. Teeth unicuspid, spatulate with slightly enlarged and conspicuously curved tips ( Fig. 7 A), visible with naked eyes in large specimens. External teeth on upper lip larger than scattered inner teeth. Single row of close set unicuspid finer teeth on lower lip.

Scales spinoid; spines rudimentary on free surface of scales, projecting along margin of scales ( Fig. 7 B). Transverse scale rows from dorsal limit of pectoral fin-base to caudal-fin base 32–36, 34, n = 86. Horizontal scale rows from spinous dorsal-fin origin to pelvic-fin origin 12–13, 11.6, n =94. Horizontal scale rows around caudal peduncle 17–18, 17.4, n = 90. Soft dorsal and anal fins densely scaled except for narrow scaleless marginal area. Basal portion of pectoral fin largely covered by small scales extending between interradial membranes but not reaching distal margin of fin. Modified axilla scale dorsal to pectoral-fin base 3 times as long as pectoral fin in 200 mm SL specimen (MZUSP 114039). Modified axilla scale dorsal to pelvic fin 2.4 times as long as pelvic fin in same specimen. Gill rakers close set; 22–56 rakers on ceratobranchial portion of first arch, increasing in number ontogenetically ( Fig. 2 )

Color in alcohol. Body dark dorsally; dark color fading ventrally towards midlateral region, whitish on abdominal region. Central portion of scales of longitudinal scale rows from midlateral region to dorsal midline of body darker, forming inconspicuous horizontal stripes in live or recently preserved specimens. Pelvic and anal fins pale with few scattered dark chromatophores. Spinous dorsal, soft dorsal, pectorals and caudal fins profusely covered with dark chromatophores. Distal margin of caudal fin darker than remaining parts of fin. Anterodorsal tip of soft dorsal fin with inconspicuous dark spot. Anterodorsal basal portion of pectoral fin with small dark spot extending over basal portions of unbranched rays, five dorsalmost branched rays and with vertically elongate whitish spot under it extending through bases of remaining ventralmost branched rays.

Remarks. The syntypes from Bahia, Brazil, MNHN 3626 are in poor condition, but it is possible to determine the following values for the specimen herein designated as lectotype (MNHN 2012-0400, SL 67.9 mm, Fig. 8 ): dorsal fin I,8; anal fin III,8; scales from dorsal-fin origin to pelvic-fin origin 12; lateral series scales 35. Lectotype designation is necessary because a single specimen of the species was not fixed as holotype in its original description (International Code of Zoological Nomenclature, 2000, Article 74). The remaining syntypes, including the specimen from Ascension Island, MNHN-3642 are herein considered paralectotypes.

Cytogenetic and molecular data. Cytogenetic data not available.

Molecular analyzes showed that the number of nucleotide differences between Mugil curvidens and the remaining analyzed species ranges from 31.0 to 69.0 (16s) and 73.2 to 105.7 (COI) (Tables 2 to 5). The genetic distance between this species and the remaining analyzed species ranged from 0.056 to 0.139 (16S) and 0.125 to 0.201 (COI) (tables 6 and 7). The dendrogram in Figure 3 shows that this species is genetically most similar to M. incilis , M. margaritae and M. curema .

Distribution. Within the study area, Mugil curvidens was collected only along the Brazilian coast, from Pará to Rio de Janeiro. It has been captured together with M. curema , M. incilis , and M. rubrioculus along the Brazilian coast ( Fig. 4 ).

No specimens of the species have been recently reported from the Southern Caribbean and Venezuela. The record of this species from the West Indies ( Thomson, 1997: 489) is based on a single not well-preserved small specimen (BMNH 1861.11.7.3, SL 78.8 mm) that has 3 spines and 9 branched anal-fin rays (vs. 3 spines and 8 branched rays in M. curvidens ). The presence of this species in Bermuda, the Bahamas and the Antilles ( Harrison, 2003, 2007) should be confirmed and it is quite possible they are based on specimens of Mugil trichodon Poey , the only other mugilid species having II+i or III+8 components in the anal fin with this and the dorsal fin almost fully scaled.

Figures

FIGURE 2. Regression of number of gill rakers versus standard length for the examined species of Mugil. Data from M. trichodon unavailable.

FIGURE 3. Dendrograms obtained by the neighbour-joining method using the Kimura- 2 - parameters model of nucleotide substitution for the data of genes COI (a) and 16 S (b). The numbers represent the groups frequencies observed using 1,000 bootstrap pseudoreplicas. Values below 50 % are not represented.

FIGURE 4. Map of central and northern South America showing collecting sites and type localities (white star and light blue star) of species of Mugil. Pink dot: Mugil trichodon, M. rubrioculus and M. incilis (Venezuela); white star: holotype of M. margaritae; white dot: M. margaritae; yellow dots: M. incilis (Brazil); green dots: M. rubrioculus (Brazil); light blue dot: M. brevirostris; blue star: neotype of M. brevirostris; red dots: M. curvidens. Some symbols may represent more than one locality.

FIGURE 7. Mugil curvidens, MZUSP 114039. A—Detail of mouth showing dentition. B—Detail of scales located on dorsal region of body below dorsal-fin base.

FIGURE 8. Mugil curvidens. Lectotype, MNHN 2012.0400, SL 69.9 mm.

Tables

TABLE 9. Morphometrics of Mugil curvidens. Standard length expressed in mm; measurements through head length are percentages of standard length; last eight entries are percentages of head length.

Characters	n	range	mean	SD
Standard length	96	25.0–197.0	72.2
Body depth	96	22.8–033.3	29.0	0 2.6
Snout to dorsal-fin origin	96	74.0–083.3	79.1	0 1.8
Snout to pectoral-fin origin	96	27.0–033.3	30.6	0 1.6
Snout to pelvic-fin origin	96	38.2–045.0	41.7	0 1.4
Snout to anal-fin origin	96	70.3–080.3	74.6	0 2.1
Caudal peduncle depth	95	09.1–012.5	11.0	0 0.8
Caudal peduncle length	96	13.6–018.8	15.5	0 1.2
Pectoral-fin length	89	18.0–022.6	20.8	0 1.2
Pelvic-fin length	95	14.6–018.7	17.2	0 1.0
Head length	96	26.2–034.2	30.6	0 2.0
Head width	96	53.3–066.0	60.3	0 2.8
Head depth	96	62.5–073.3	69.0	0 2.2
Lip thickness	86	04.0–007.4	0 5.3	0 0.7
Mouth width	95	22.7–029.4	25.0	0 1.3
Mouth depth	94	20.0–026.1	22.6	0 1.4
Horizontal orbital diameter	96	24.0–033.3	29.2	0 2.0
Snout length	95	20.0–025.8	22.6	0 1.6
Upper jaw length	95	22.1–029.4	25.4	0 1.6