Hyphessobrycon lucenorum, Ohara, Willian M. & Lima, Io. C. T., 2015

Ohara, Willian M. & Lima, Io. C. T., 2015, Hyphessobrycon lucenorum (Characiformes: Characidae), a new species from the rio Madeira basin, Rondônia State, Brazil, Zootaxa 3972 (4), pp. 562-572 : 563-567

Hyphessobrycon lucenorum , new species

( Figures 1 , 3 ; Table 1 )

Holotype. MZUSP 115556, 35.4 mm SL. Brazil, Rondônia, Vilhena, rio Madeira basin, upper rio Machado, tributary of igarapé Piracolina , near road BR 364, 12°48’56.5”S 60°06’37.6”W, 7 September 2014, W. M. Ohara & P. L. Cunha.

Paratypes. All from Brazil, Rondônia, Vilhena. MZUSP 115522, 16, 25.9–32.9 mm SL; ANSP 197264, 3, 25.9–29.6 mm SL; MCP 48326, 3, 25.7–26.7 mm SL; same data as holotype. UFRO-I 22909, 1, 20.4 mm SL; MZUSP 115558, 10, 16.0– 34.1 mm SL, 1 c&s, 29.3 mm SL; INPA 46073, 3, 19.4–31.9 mm SL same locality as holotype, 19 July 2013, I. D. da Costa; UFRO 22724, 14, 16.1–32.9 mm SL; MZUSP 115557, 10, 17.1–31.6 mm SL, 3 c&s, 17.7–33.6 mm SL; ZUEC 8573, 4, 17.8–31.4 mm SL; same locality as holotype, 14 September 2013, W. M. Ohara, D. B. Hungria & B. S. Barros. MNRJ 13456, 10, 22.1–31.2 mm SL, igarapé Piracolina , 12°43’34’’S 60°11’38’’W; 18 Jul 1986, G. W. Nunan & W. D. Bandeira.

Diagnosis. Hyphessobrycon lucenorum can be distinguished from all congeners by the combination of the presence of a single, conspicuous, rounded dark humeral blotch (vs. humeral blotch, when present and single, variously shaped but never well-defined and rounded, with the exception of Hyphessobrycon langeanii Lima & Moreira, 2003), and the presence of a broad, diffuse, dark longitudinal stripe extending from immediately posterior of the humeral blotch to the central caudal-fin rays (vs. longitudinal midlateral stripe, when present, relatively narrow and intensely pigmented, with exception of H. agulha Fowler, 1913 , H. herbertaxelrodi Géry, 1961 , H. loretoensis Ladiges, 1938 , H. metae Eigenmann & Henn, 1914 , H. mutabilis Costa & Géry, 1994 and H. peruvianus Ladiges, 1938 ). Additional features distinguishing the new species from the aforementioned species are presented in the Discussion.

Description. Morphometric data for the holotype and paratypes presented in Table 1 . Body compressed, moderately short and deep. Greatest body depth situated slightly anterior to vertical through dorsal-fin origin. Dorsal profile of head convex from tip of upper jaw to vertical through anterior nostril; straight or slightly concave from that point to tip of supraoccipital spine. Dorsal profile of body convex from supraoccipital spine tip to base of last dorsal-fin ray, approximately straight from that point to adipose-fin insertion and slightly concave between adipose-fin insertion and origin of anterior most dorsal procurrent caudal-fin ray. Ventral profile of head and body convex from tip of dentary to anal-fin insertion. Body profile along anal-fin base straight and posterodorsally slanted. Ventral profile of caudal peduncle slightly concave.

Jaws equal, mouth terminal. Posterior terminus of maxilla reaching vertical through slightly anterior to middle of pupil. Maxilla approximately at 45 degree angle relative to longitudinal axis of body. Nostrils close to each other, anterior opening circular, posterior opening crescent-shaped. Nostrils separated by narrow flap of skin.

Premaxillary teeth in two rows; outer teeth row with 2 (1), 3* (16) or 4 (9) tricuspid teeth; inner teeth row with 5* (28), 6 (1) or 7 (2) teeth with three to five cusps, symphyseal tooth of inner series narrow and asymmetric. Maxilla with 5 (4), 6 (13), 7* (5) or 8 (3) teeth along anteroventral margin, with one or three cusps ( Fig. 2 ); anterior most tooth usually largest. Dentary with 4 (1) or 5* (11) tri- to pentacuspid teeth, followed by series of 11 (2), 12 (1) or 13(1) small conical or tricuspid teeth, considerably smaller than anterior teeth. Central cusp of all teeth most developed than remaining lateral cusps; cusp tips slightly curved inward on dentary teeth, and outward on premaxillary teeth.

Scales cycloid, moderately large, circuli distributed over whole area of scales with five to seven slightly divergent radii extending to posterior margin of scales in longitudinal scale series. Lateral line slightly deflected downward and incompletely pored, with 5 (2), 6 (11), 7* (8), 8 (4) or 9 (2) perforated scales. Longitudinal scales series including lateral-line scales 30 (4), 31 (13), 32 (11) or 33* (5). Longitudinal scale rows between dorsal-fin origin and lateral line 5 (7) or 6* (26). Longitudinal scale rows between lateral line and pelvic-fin origin 3 (12) or 4* (24). Scales in median series between tip of supraoccipital spine and dorsal-fin origin 8* (4), 9 (13), 10 (7), or 11 (11). Horizontal scale rows around caudal peduncle 12* (31) or 13 (1). Single row of three (3), 4 (5), or 5 (5) scales covering base of anterior most anal-fin rays. Caudal fin with scales only basally.

Dorsal-fin rays ii, 9* (37) or iii, 8 (1). Dorsal-fin origin at middle of standard length and slightly posterior to vertical through pelvic-fin origin. First unbranched dorsal-fin ray shorter than second ray. First dorsal-fin pterygiophore located behind neural spine of 9th (4) vertebrae. Adipose fin present. Anal-fin rays iv, 17 (7), 18* (21), or 19 (9), anteriormost rays slightly longer, subsequent rays gradually decreasing in size; distal margin of anal fin slightly concave or straight. Pectoral-fin rays i, 10* (22), 11 (13) or 12 (3). Tip of pectoral fin reaching slightly beyond pelvic fin insertion. Pelvic-fin rays i, 7* (38). Tip of pelvic fin reaching anterior portion of anal fin. Principal caudal-fin rays 10+9 (24). Caudal-fin forked, lobes somewhat pointed and of similar size. Eight (1) or 9 (3) dorsal procurrent caudal-fin rays, and 8 (4) ventral procurrent caudal-fin rays. Vertebrae 32 (4). Supraneurals 4 (4) with bony lamellae on upper portion. Branchiostegal rays 4. First gill arch with one (3) or 2 (1) hypobranchial, 8 (3) or 9 (1) ceratobranchial, 1 on cartilage between ceratobranchial and epibranchial, and 5 (4) epibranchial gillrakers.

Color in alcohol. Overall body color beige, darker dorsally. Small dark chromatophores densely concentrated on dorsal surface of head, premaxilla, anterior portion of maxilla and dentary, antorbital and infraorbitals 1, 4 and 5. Infraorbitals 2–3, preopercle and lower half of opercle clear or with silvery tinge, with scattered dark chromatophores. Ventral portion of head clear. Dorsal region brown. First three dorsal horizontal scale rows on body with slightly reticulated pattern formed by dark pigmentation concentrated along scale borders. Narrow pale stripe situated immediately above humeral blotch and longitudinal stripe, extending posterodorsally from posterior upper corner of eye to caudal peduncle. Dark humeral blotch very conspicuous, typically rounded, slightly smaller than eye diameter. Humeral blotch in some specimens not perfectly rounded with ventral portion slightly blurred. A broad, 2 to 2.5 scales high, diffuse grayish-brown longitudinal stripe, extending immediately posterior to humeral blotch to end of caudal-peduncle, and extending over middle caudal-fin rays as faint stripe. Dark chromatophores on lower portion of body arranged along myosepta of the hypaxial muscle bundles from area above anal fin to caudal peduncle. Abdominal region beige with few small dark, sparsely distributed chromatophores. Dorsal, anal and caudal fins with dark chromatophores scattered mainly over interradial membranes and fin margins. Distal portion of pelvic and pectoral-fins with chromatophores on lepidotrichia and interradial membranes. Adipose fin with dark chromatophores present mainly along distal margin.

Color in life. Based on photographs taken in the field of twenty specimens. Males more vividly-colored but otherwise similar in color pattern to females. Overall body coloration light brown dorsally, light to yellowish color ventrally. Humeral blotch and longitudinal broad dark stripe conspicuous. Longitudinal stripe with plumbeous tinge. Lower half of opercle and infraorbitals 2–3 bones silvery. Upper half of opercle and infraorbitals 4–5 dark, with plumbeous tinge. Upper portion of eye red. Males with basal portion of the anal fin and basal portion of ventral lobe of caudal fin intensely red in some individuals, pale red, suffused with yellow in others. Posterior half of anal fin yellowish or reddish. Anal-fin base and lower half of caudal peduncle of males suffused with red pigmentation. Females with anal fin yellowish, without red pigmentation. Adipose-fin basally yellowish, with distal margin translucent; some males with adipose fin red. Pectoral fin yellow. Pelvic fin light yellow in females, dark yellow or orange with distal portion darkened in males. Basal portions of dorsal and caudal fins yellowish or with orange tint. Ontogenetic change in the color in life was not observed.

Sexual dimorphism. As described in “Color in life”, males are typically more brightly-colored than females, especially in the fins ( Fig. 3 ). Additionally, males possess a less pointed anal-fin lobe, imparting a straighter overall profile when compared with the slightly concave anal-fin profile in females. Bony hooks on fins, a common dimorphic feature in characids ( Malabarba & Weitzman, 2003), were not found in any specimen.

Ecological notes. The type locality of Hyphessobrycon lucenorum is a small, clear water stream 1.5–2.5 m wide and 0.3–1.5 m deep, with vegetation, swift water current, and a bottom composed by sand and dead leaves ( Fig. 4 ). Individuals of Hyphessobrycon lucenorum were observed during snorkeling singly or in small groups of 3–6 individuals, swimming in mid water settings. Other species sampled syntopically were Bryconops piracolina Wingert & Malabarba 2011 , Cetopsorhamdia sp. 3 (cf. Bockmann & Slobodian, 2013: 25), Hyphessobrycon aff. melonostichos Carvalho & Bertaco, 2006, Ancistrus verecundus Fisch-Muller, Cardoso , da Silva & Bertaco, 2005, Corydoras sp. and Hyphessobrycon sp. The type-locality is near the town of Vilhena and is surrounded by large cultivated farmlands.

The analysis of the stomach contents of four paratypes (c&s) revealed the presence of ants, larvae of Diptera (chironomids) and Odonata, unidentified insect fragments, copepods, unidentified vegetal fragments and sediment.

Distribution. The new species is known from its type locality, a headwater tributary of igarapé Piracolina and from the igarapé Piracolina iself, which is a tributary of the upper rio Machado, rio Madeira basin, Rondônia State, Brazil ( Fig. 5 ).

Etymology. The specific name is in honor of Carlos A. S. de Lucena and Zilda M. S. de Lucena, curators and researchers at the Museu de Ciência e Tecnologia da Pontifícia Universidade Católica do Rio Grande do Sul, in recognition of their contributions to the knowledge of the Neotropical ichthyofauna, especially of characid fishes. A genitive noun.

Figures

FIGURE 1. Hyphessobrycon lucenorum new species, holotype, MZUSP 115556, 35.4 mm SL, female.

FIGURE 2. Hyphessobrycon lucenorum, medial view of right side, premaxilla and maxilla, MZUSP 115557, paratype, 33.6 mm SL and dentary, MZUSP 11558, paratype, 29.3 mm SL. Scale bar: 1 mm.

FIGURE 3. Type-locality (square) of Hyphessobrycon lucenorum new species, a tributary of the igarapé Piracolina, upper rio Machado drainage, rio Madeira basin, Vilhena, Rondônia, Brazil.

FIGURE 4. Headwater of igarapé Piracolina, upper rio Machado, Vilhena, Rondônia, Brazil, type-locality of Hyphessobrycon lucenorum.

FIGURE 5. Hyphessobrycon lucenorum, paratypes: a) MZUSP 115522, female, 32, 9 mm SL; b) UFRO-I 22724, male, 29, 1 mm SL, immediately after capture.

Tables

TABLE 1. Morphometric data for holotype and paratypes of Hyphessobrycon lucenarum, included in number of specimens (n = 28). S. D = Standard Deviation.

	Holotype	Range	Mean ± S.D.
Standard length (mm)	35.4	19.4–35.4	28.8
Percents of standard length
Depth at dorsal-fin origin	35.5	31.3–37.8	35.2 ± 1.5
Snout to dorsal-fin origin	51.6	50.4–56.7	52.7 ± 1.4
Snout to pectoral-fin origin	30.0	28.2–35.6	30.3 ± 1.7
Snout to pelvic-fin origin	47.4	44.4–51.5	47.4 ± 1.4
Snout to anal-fin origin	62.0	59.1–64.5	61.9 ± 1.6
Caudal peduncle depth	12.5	9.4–13.1	11.6 ± 1.0
Caudal peduncle length	14.0	12.8–16.7	14.3 ± 0.9
Pectoral-fin length	21.9	18.1–25.0	22.2 ± 1.6
Pelvic-fin length	17.1	15.2–21.0	17.6 ± 1.2
Pelvic-fin origin to anal-fin origin	15.8	13.7–19.5	16.2 ± 1.2
Dorsal-fin base	14.1	12.8–15.7	14.3 ± 0.7
Dorsal-fin length	28.9	26.5–31.5	29.3 ± 1.4
Dorsal-fin origin to caudal-fin origin	54.6	48.7–56.1	53.5 ± 1.5
Anal-fin base	28.2	25.9–29.4	27.3 ± 0.9
Anal-fin length	20.8	19.0–23.8	21.3 ± 1.1
Posterior margin of eye to dorsal-fin origin	37.3	35.6–40.1	38.0 ± 1.0
Head length	27.4	27.4–31.7	29.3 ± 1.0
Percents of head length
Horizontal orbital diameter	40.2	34.4–44.0	39.6 ± 2.1
Snout length	22.3	21.1–25.3	22.5 ± 1.1
Least interorbital width	28.1	25.0–31.0	28.1 ± 1.3
Upper jaw length	46.4	42.3–48.7	45.2 ± 1.6