Hyphessobrycon rutiliflavidus, Carvalho, Fernando Rogirio, Langeani, Francisco, Miyazawa, Carlos Suetoshi & Troy, Waldo Pinheiro, 2008

Carvalho, Fernando Rogirio, Langeani, Francisco, Miyazawa, Carlos Suetoshi & Troy, Waldo Pinheiro, 2008, Hyphessobrycon rutiliflavidus n. sp., a new characid fish from the upper rio Paraguai, State of Mato Grosso, Brazil (Characiformes: Characidae), Zootaxa 1674, pp. 39-49 : 40-44

Hyphessobrycon rutiliflavidus new species

Fig. 1

Holotype. DZSJRP 7444, female, 50.7 mm SL: Brazil, State of Mato Grosso, Cuiabả, córrego Pipa (15°41’23.4”S 55°29’48.8”W), rio Paraguai drainage, next to Serra de São Vicente, col. W.P.Troy, 10 November 2002.

Paratypes. (same data as holotype) DZSJRP 5347, 8 (1 c&s), 38.8–42.0 mm SL, 10 December 2002; DZSJRP 6653, 9, 28.0–55.0 mm SL, 10 November 2002; DZSJRP 6654, 12 (1 c&s), 33.1–42.3 mm SL, 10 December 2002; DZSJRP 8502, 21 of 27 (1 c&s), 25.5–58.1 mm SL, 10 November 2002; LIRP 5945, 3, 27.6–35.1 mm SL, 10 November 2002; MCP 40975, 4, 38.9–44.3 mm SL, 10 November 2002; MNRJ 30121, 3, 34.2–39.5 mm SL, 10 November 2002; MZUSP 92438, 4, 35.8–37.4 mm SL, 10 November 2002.

Diagnosis. Hyphessobrycon rutiliflavidus differs from its congeners by the following combination of characters: black humeral spot, slightly diffuse at tips, and caudal-peduncle blotch present; midlateral longitudinal body stripe, most conspicuous in its posterior portion, from vertical through anterior third of pectoral fin to caudal-peduncle blotch, extending through median caudal-fin rays; anal fin with iii,15 to iv,19 rays (mode iv,17); upper jaw length 42.3 to 49.5% HL; maxilla with 2–5 teeth (mode 3); all fins of male reddish-orange and of female yellowish.

Description. Morphometric data in Table 1 . Body moderately deep, less so in individuals smaller than 28 mm SL; greatest body depth at vertical through dorsal-fin origin. Dorsal profile of head convex from snout to nostrils and slightly convex from nostrils to supraoccipital spine. Dorsal profile of body convex from head to dorsal-fin origin and slightly convex from dorsal-fin base to adipose-fin base, with inflection at dorsal-fin termination. Caudal peduncle slightly concave dorsally and straight ventrally. Ventral profile of head strongly convex anteriorly to isthmus. Ventral profile of body convex from pectoral-fin origin to pelvic-fin base; slightly convex or straight from pelvic-fin base to anal-fin origin; straight and ascendant along anal-fin base.

Head anteriorly rounded in lateral profile. Jaws equal, mouth terminal. Maxilla forming angle of approximately 45° relative to longitudinal axis of body, extending under orbit to vertical through posterior margin of pupil, but not reaching suture between second and third infraorbitals. Nostrils close to one another, anterior opening smaller and circular, posterior larger and oval. Eye relatively large and without adipose eyelid. Frontals slightly united anteriorly; median frontoparietal fontanel extending from mesethmoid to supraoccipital spine; width of fontanel approximately one-fourth of interorbital distance. Infraorbital series complete. First infraorbital, and usually second, with laterosensory canal close to inner margin of orbital rim; third to sixth infraorbitals with laterosensory canal away from orbital rim. Third infraorbital largest, double size of others and in contact with preopercle laterosensory canal inferiorly and laterally. Supraorbital absent. Four branchiostegal rays, 3 (3) along anterior ceratohyal, and 1 (3) along posterior ceratohyal. Gill-rakers of first branchial arch distinctly long, setiform and with small spines, decreasing in size progressively from first gill-raker from ceratobranchial to last from hypobranchial; epibranchial with gill-rakers of size same approximately; epibranchial with 7 (3) rakers, ceratobranchial with 9 (2) or 10 (1), cartilage between ceratobranchial and epibranchial with 1 (3), and hypobranchial with 2 (2) or 3 (1) gill-rakers.

Premaxillary teeth, tri- to pentacuspid, in two series: outer 2 (2), 3* (32), or 4 (11) and inner with 4 (3), 5* (42), or 6 (1) ( Fig. 2 ). Maxillary teeth 2 (5), 3 (31), 4 (15), or 5* (1), tri- to pentacuspid, in proximal portion. Dentary with 4 (12), or 5* (36) large, tri- to pentacuspid teeth, followed by 8 (3) teeth, smaller and conical, uni- to tricuspid in single row. All teeth with central median cusp larger than other cusps and curved posteriorly towards inside of mouth, except small teeth in posterior portion of dentary, not curved.

Scales cycloid and firmly implanted, with 9 to 20 radii. Lateral line incompletely pored, anteriorly curved, with 10 (3), 11 (5), 12 (12), 13* (16), 14 (6), 15 (5), 16 (4), or 17 (4) perforated scales; longitudinal series, including perforated scales, with 30 (3), 31 (11), 32 (17), 33* (14), or 34 (10). Transversal scale rows, from dorsal-fin origin to lateral line 5 (5) or 6* (50), and from lateral line to pelvic-fin origin, 4 (3), 4½ (11), 5* (39), or 5½ (2). Predorsal scales regular with 9 (2), 10 (7), 11 (33), 12* (12), or 13 (1), from tip of supraoccipital spine to dorsal-fin origin. Single row of 3 (6), 4 (13), 5 (8), 6 (13), or 7* (12) scales covering base of anteriormost anal-fin rays. Scale rows around caudal peduncle 13 (7), or 14* (48). Axillary scale present. Caudal fin scaled just at base.

Total vertebrae 32 (2) or 33 (1); precaudal vertebrae 16 (3) and caudal 16 (2) or 17 (1). First dorsal-fin pterygiophore inserted behind neural spine of 10th vertebra; first anal-fin pterygiophore just after 16th (2) or 17th (1) vertebrae. Supraneurals 4 (1) or 5 (2), filiform, sometimes slightly triangular or with upper portion enlarged.

Dorsal fin at vertical just posterior of pelvic-fin base with ii,9* (54) rays; first unbranched ray approximately half length of second unbranched ray, dorsal-fin margin distally rounded to slightly acute. Adipose fin origin at vertical just posterior of two posteriormost anal-fin rays. Pectoral-fin with i,9 (1), i,10 (22), i,11* (31), or i,13 (1) rays; distinctly acute in lateral view, never reaching pelvic-fin base. Pelvic-fin with i,5 (3), i,6* (50), or i,7 (1) rays, originating through vertical or little anterior of dorsal-fin origin, and rarely extending to anal-fin origin; shorter than pectoral fin and slightly acute in lateral view, with the first rays longest. Pelvicfin hooks on first three branched rays of males larger than 38 mm SL. Anal-fin rays iii,15 (1), iii,16 (9), iv,16* (9), iii,17 (7), iv,17 (22), iii,18 (2), iv,18 (3), or iv,19 (1). Anal fin of male larger than 38 mm SL with one pair of short hooks for hemitrichia, on distal portion of last unbranched ray and first three branched rays ( Fig. 3 ); its distal margin straight and usually longest at second or third branched rays, decreasing posteriorly. Anal fin of female with anterior distal margin slightly rounded, third or fourth unbranched rays longest, other rays moderately decreasing in length up to 9th or 10th and the slightly decresing in length. Caudal fin forked, dorsal and ventral lobes similar in size, distal tips slightly rounded to acute, i,8/8,i (2) or i,9/8,i* (48) principal rays; dorsal procurrent caudal-fin rays 12 (2), and ventral 10 (2) or 11 (1).

Color in life. Males and females grayish along dorsal and lateral portions of body, including longitudinal stripe; whitish ventrally. Fins of male reddish to orange with conspicuous reddish stripes along anal-fin base and ventral portion of caudal-peduncle; fins of female yellowish with more conspicuous yellowish stripe along anal-fin base.

Color in alcohol. Overall body coloration yellowish-brownish to dark grey. Snout and dorsal portion of head relatively dark. Dorsal portion of body, from supraoccipital spine to caudal peduncle, darker than remaining portions. Opercle, particularly upper portion, with more concentration of dark chromatophores than remaining portions of head. Humeral spot vertically elongate, diffuse, just posterior upper portion of opercular opening, at vertical through posterior portion of pectoral-fin base; second humeral spot not conspicuous, united to longitudinal stripe. Longitudinal stripe narrow anteriorly and wider posteriorly, extending from vertical through posterior third of pectoral fin to middle caudal-fin rays, between epaxial and hypaxial musculature, enlarged at caudal peduncle and proximal portion of middle caudal-fin rays, forming an oval, horizontally positioned, and relatively diffuse spot.

Fins hyaline, sometimes slightly dark grey. Border of anal fin and middle caudal-fin rays slightly darker.

Sexual dimorphism. Males with reddish fins, distal margin of anal fin relatively straight, and small hooks on pelvic and anal fins of mature specimens; females with fins yellowish, distal margin of anal fin slightly convex and hooks absent.

Distribution. Hyphessobrycon rutiliflavidus is until now only known from the type-locality: córrego Pipa, upper rio Paraguai drainage ( Fig. 4 ).

Etymology. The species name rutiliflavidus , from latin rutilus, reddish, plus flavidus, yellowish, referring to the in vivo coloration of fins, respectively, in males and females. An adjective.

Ecological notes. The córrego Pipa, in the Serra de São Vicente, State of Mato Grosso, is situated approximately 479 m above sea level. Its riparian vegetation is relatively well conserved, surrounded by cerrado formation. Riffles, runs, and pools are present, and Hyphessobrycon rutiliflavidus occurs preferentially in lentic portions. The water is cold and transparent; bottom is mostly of silt and rocks. Syntopic species, collected with cast nets and fish-hooks, were Parodon aff. nasus , Astyanax asuncionensis Gẻry, Knodus chapadae (Fowler) , Hypostomus sp., and Ancistrus sp. Stomach contents of five specimens of Hyphessobrycon rutiliflavidus examined contained debris of vascular plants, algae, and arthopods (Aranae and Hymenoptera - Formicidae ).

Figures

FIGURE 1. Hyphessobrycon rutiliflavidus, holotype, DZSJRP 7444, female, 50.7 mm SL; Brazil, State of Mato Grosso, Cuiab ả, córrego Pipa, rio Paraguai drainage, next to Serra de São Vicente.

FIGURE 2. Hyphessobrycon rutiliflavidus, paratype, DZSJRP 8502, 45.7 mm SL, premaxilla, maxilla and dentary, left lateral view. Scale bar 1 mm.

FIGURE 3. Hyphessobrycon rutiliflavidus, paratype, DZSJRP 6654, 39.8 mm SL, anal fin of male with hooks, lateral view, left side. Scale bar 1 mm.

FIGURE 4. Type-locality of Hyphessobrycon rutiliflavidus: córrego Pipa, (15 ° 41 ’ 23.4 ” S 55 ° 29 ’ 48.8 ” W), upper rio Paraguai drainage, next to Serra de São Vicente, State of Mato Grosso, Cuiab ả municipality.

Tables

TABLE 1. Morphometric values of Hyphessobrycon rutiliflavidus. Standard length in millimeters; SD = Standard Deviation; n = 55 specimens.

Holotype	Paratypes	Mean	SD
Standard length 50.7	28.0–58.1	39.8	5.2
Percents of standard length
Body depth 32.7	30.9–36.7	33.9	1.4
Head length 28.0	26.8–30.2	28.8	0.7
Head depth 29.6	27.4–33.3	30.5	1.0
Predorsal length 51.3	50.0–53.8	51.7	0.9
Preventral length 48.7	48.3–52.8	50.2	0.9
Pelvic-fin to anal-fin distance 16.8	13.9–18.6	16.5	1.1
Caudal peduncle depth 13.4	12.3–14.3	13.4	0.4
Dorsal-fin base length 15.8	14.3–16.5	15.3	0.6
Anal-fin base length 23.1	20.8–27.2	23.5	1.4
Pectoral-fin length 17.9	18.4–23.6	20.7	1.0
Pelvic-fin length 13.6	12.4–17.9	15.3	1.0
Dorsal-fin length 25.2	23.1–29.9	27.3	1.5
Anal-fin length 17.4	12.2–20.5	15.5	1.5
Caudal peduncle length 16.2	14.4–18.8	16.9	1.0
Dorsal-fin to adipose-fin distance 35.5	34.0–38.6	36.1	1.0
Eye to dorsal-fin origin 38.9	34.7–40.4	37.6	1.2
Dorsal-fin origin to caudal fin origin 51.3	49.9–55.5	53.2	1.2
Percents of head length
Orbital diameter 29.6	27.8–37.2	33.1	1.8
Snout length 25.4	22.3–26.6	24.6	1.0
Interorbital width 33.8	29.8–36.2	33.2	1.4
Upper jaw length 42.3	43.1–49.5	46.4	1.6