A new species of Hyphessobrycon (Characiformes: Characidae) from río Portuguesa, río Orinoco basin, Venezuela
Author
Benine, Ricardo C.
Author
Lopes, Guilherme A. M.
text
Zootaxa
2008
1747
61
68
journal article
49706
10.5281/zenodo.181686
a8aa218a-a409-4aac-aa27-edbf56e3ae4f
1175-5326
181686
Hyphessobrycon otrynus
new species
(
Table 1
,
Figs. 1–4
)
Holotype
.
USNM
349418,
30.1 mm
SL.
Venezuela
, Portuguesa, río Portuguesa drainage, río Las Marias, at Quebrada Seca, aproximatelly 45 min upstream by car from Highway 5, 22 km NNW Guanare. J. Armbruster and
O
. Leon.
28 Feb. 1998
(fig. 1).
Paratypes
.
All from
Venezuela
.
USNM
392814,
29.7mm
SL (same data as
holotype
);
LIRP
6040,
8 specimens
,
21.5–25.7 mm
SL, and
2 specimens
C&S, 24.0–
24.2 mm
SL, Caño Falcon, río Portuguesa, J. N. Baskin.
24 Nov. 1974
.
FIGURE 1.
Hyphessobrycon otrynus
, USNM 349418, holotype, 30.1 mm SL, Venezuela, Portuguesa, río Portuguesa.
Diagnosis
. This species is distinguished from all other known congeners, except for
H. diancistrus
, by the presence of two very large bony hooks (in adult males) curving dorsally on each side of anal fin, and caudalfin rays black at distal third of their length (distal tips of caudal-fin rays hyaline).
Hyphessobrycon otrynus
is promptly distinguished from
H. diancistrus
by possessing iv,19–21 anal fin rays, versus iv,14 anal-fin rays in the latter. Adult males of
H. otrynus
are also distinguished from
H. diancistrus
by presenting very small analfin hooks, lacking from the latter species. Moreover, in
H. otrynus
, the very large bony hooks are located on the fourth or fifth segments of the last unbranched anal-fin ray and on the fifth segment of the first branched anal-fin ray, whereas in
H. diancistrus
the bony hooks are located on the first and third segments of the last unbranched and first branched anal-fin rays.
Among small characins,
Hyphessobrycon otrynus
is most similar to
Moenkhausia bonita
and
Hemigrammus marginatus
, from which it differs in having a naked caudal-fin (vs. a scaled caudal-fin), by presenting two large hooks on anal-fin of adult males (not observable in latter species), and ii,8 dorsal-fin rays (vs. ii,9 dorsalfin rays).
Hyphesssobrycon otrynus
is also distinguished from
M. bonita
in having an incompletely pored lateral line (vs. completely pored lateral line).
Description.
Morphometric data for
Hyphessobrycon otrynus
are summarized in
Table 1
. Body fusiform. Greatest body depth at dorsal-fin origin. Dorsal profile of head straight or slightly convex. Dorsal profile of body slightly convex from posterior tip of supraoccipital spine to dorsal-fin origin, straight or slightly convex and posteroventrally slanted along dorsal-fin base, straight or slightly convex from end of dorsal-fin base to end of adipose-fin, and slightly concave along caudal peduncle. Ventral body profile convex from anterior tip of lower jaw to caudal-peduncle origin, slightly concave along caudal peduncle. Pelvic region transversally flattened, more so proximal to pelvic-fin insertion, becoming somewhat obtuse toward anal-fin origin.
TABLE 1
. Morphometric data for
Hyphessobrycon otrynus
,
new species
.
holotype |
N |
paratypes |
limits |
mean |
Standard length (mm) |
30.1 |
11 |
22.4–29.4 |
24.5 |
Percentage of standard length |
Greatest depth |
29.8 |
11 |
28.8–33.8 |
31.6 |
Snout to dorsal-fin origin |
52.2 |
11 |
49.8–54.8 |
52.5 |
Snout to pectoral-fin origin |
29.6 |
11 |
26.7–31.8 |
30.2 |
Snout to pelvic-fin origin |
45.7 |
0 9 |
44.7–50.4 |
47.7 |
Snout to anal-fin origin |
64.0 |
11 |
63.1–66.4 |
64.9 |
Caudal peduncle depth |
10.7 |
11 |
9.4–10.7 |
10.1 |
Caudal peduncle length |
12.1 |
11 |
11.7–12.9 |
12.4 |
Pectoral-fin length |
22.9 |
10 |
22.0–25.2 |
23.2 |
Pelvic-fin length |
20.9 |
10 |
17.6–21.5 |
19.8 |
Dorsal-fin length |
26.8 |
10 |
20.0–28.8 |
27.0 |
Dorsal-fin base |
15.0 |
11 |
12.2–15.6 |
14.4 |
Anal-fin length |
20.2 |
10 |
18.0–20.2 |
19.9 |
Anal-fin base |
26.1 |
11 |
24.5–28.5 |
26.7 |
Eye to dorsal-fin origin |
38.9 |
0 9 |
38.1–39.7 |
39.1 |
Dorsal-fin origin to caudal-fin origin |
51.7 |
0 9 |
48.8–52.8 |
50.9 |
Head length |
26.5 |
11 |
26.3–29.1 |
28.0 |
Head depth |
16.7 |
11 |
16.6–19.6 |
18.3 |
Percentage of head length |
Snout length |
25.9 |
11 |
24.9–26.8 25.7 |
Upper jaw length |
41.4 |
11 |
38.7–41.5 40.3 |
Horizontal orbital diameter |
36.7 |
11 |
34.9–39.8 37.3 |
Least interorbital width |
31.0 |
11 |
27.6–31.3 29.6 |
Mouth terminal. Jaws equal or lower jaw slightly longer than upper jaw. Most posterior margin of maxilla trespassing vertical through anterior margin of orbit. Premaxillary teeth in two rows; outer tooth row with 3 (4), 4* (6) conical to tricuspid teeth, midcentral cusps longer than others; inner tooth row with 5 tri to pentacuspid teeth in all specimens, midcentral cusps longer than others. Maxillary with 0 (2) and 1*(8) conical tooth. Dentary with 4 tri to pentacuspid teeth followed by a smaller tricuspid one, and a short series of small conical teeth in all specimens (fig. 2). Palatine and pterygoid bones toothless.
Frontals contact each other at their anterior one-fifth and at epiphyseal bar. Parietal bones completely separated by frontal-parietal fontanel. Infraorbital series well ossified.
FIGURE 2.
Hyphessobrycon otrynus
, LIRP 6040, paratype, 24.2 mm SL, premaxillary, maxillary and dentary; left side, lateral view (maxillary and dentary) or frontal view (premaxillary). Scale bar = 1 mm.
Nostrils closer to anterior orbital margins than to each other. Supraoccipital process short, its posterior tip not reaching the vertical through posterior margin of opercle.
Dorsal-fin rays ii,
8 in
all specimens. Pectoral-fin rays i,10,i in all specimens. Distal tip of pectoral fin slightly trespasses vertical through pelvic-fin insertion. Adipose fin present. Pelvic-fin rays i,
7 in
all specimens; when adpressed, its tip reaches base of second branched anal-fin ray. Anal-fin rays v,19(6) or 21*(4). Principal caudal-fin rays i,17,i. Caudal-fin forked.
Scales cycloid, with few radii along posterior border. Lateral line incomplete, pored scales 8* (2), 9 (1), 12(3). Lateral series of scales including lateral-line pored scales 31*(3), 32(3). Scale rows between dorsal-fin origin and lateral line 5; scale rows between lateral line and pelvic-fin origin 3. Scale sheath along anal-fin base in a single series of 4 scales, extending posteriorly up to fourth branched anal-fin ray.
First gill arch with 13(4), 14*(5) gill rakers on ventral limb and 7(1), 8*(9) on dorsal limb. Total vertebrae 33, supraneurals 5 (fig.3).
Sexual dimorphism.
Adult males with two very large, dorsally curved hooks on both sides of anal fin, somewhat buried in thick tissue; anterior hook longest, being a process of the fifth (last unbranched) anal-fin ray; posterior hook being a process of sixth (first branched). Small hooks are located on the distal segments of most anterior anal-fin rays, more concentrated on the segments of the posterior branch of each hooked ray (figs. 3, 4). All small hooks are backward pointed and varying in number from one to four per ray segment. One individual also presented a somewhat more developed hook on each side of the second and third branched anal-fin rays.
FIGURE 3.
Radiograph of
Hyphessobrycon otrynus
, USNM 349418, holotype, 30.1 mm SL, Venezuela, Portuguesa, río Portuguesa.
Color in alcohol.
Overall coloration pale yellow. A dark stripe extending along horizontal septum, more intense from vertical passing through the origin of the second scale most anterior to dorsal fin. Median dorsal scale row, from nape to dorsal caudal-fin origin, densely scattered with dark chromatophores. Anterior to dorsal-fin end, scales of second and third scale rows ventral to median dorsal scale row posteriorly emarginated by dark chromatophores, with pigment concentration diminishing downward. From dorsal-fin end to adiposefin origin, scales of row immediately ventral to median dorsal scale row posteriorly emarginated by dark chromatophores. Very few chromatophores scattered on opercle. Lateral line sensorial canals bordered by few dark chromatophores. Limits of caudal epaxial and hipoaxial, and anal-fin inclinator muscle masses, partially outlined by dark chromatophores (see fig.1). Caudal peduncle with a somewhat horizontal lozenge-shaped black blotch that faint toward distal tips of middle caudal-fin rays.
Head with a dense field of dark chromatophores in region just posterior to epiphyseal bar. Sparsely scattered dark chromatophores anterior to epiphyseal bar. A dense patch of dark chromatophores dorsal to snout, between and surrounding area of nostrils, premaxillary bones and dorsal portion of maxillary bones. A dense patch of dark chromatophores on symphyseal area of dentary bones. A thin line of dark chromatophores bordering orbits. Remainder of head pale yellowish white.
Dorsal fin with scattered dark pigments bordering rays along their length. Anal fin with scattered dark pigments bordering fin rays, more concentrated along its proximal and distal length, resulting in a somewhat clearer medial area in few individuals. Adipose fin with scattered dark chromatophores along its area, except for its distal one third, which is hyaline. Paired fins hyaline with scattered dark pigments, more concentrated on intermembranes of unbranched ray. Midregion of both caudal-fin lobes with a field of dark chromatophores. Tips and base of both lobes of caudal fin hyaline (fig.1).
Distribution
. Known only from tributaries of the río Portuguesa, río Orinoco drainage,
Venezuela
(fig. 5).
FIGURE 4.
Hyphessobrycon otrynus
, LIRP 6040, paratype, 24.2 mm SL,. Partial view of anterior anal-fin rays showing the two large hooks on the last unbranched and first branched anal-fin rays, and the small hooks on the first to third branched anal-fin rays. Right side, lateral view. Scale bar = 1mm.
FIGURE 5.
Map showing the type locality of
Hyphessobrycon otrynus
.
Etymology
. The specific epithet
otrynus
is from the Greek meaning spur, in reference to the two very large spur-like hooks (processes of last unbranched and first branched anal-fin rays).
Comments
. According to Ellis (in
Eigenmann, 1918
),
Hyphessobrycon
is distinguished from
Hemigrammus
only by presenting a naked caudal fin in opposition of the scaled caudal fin in the last genus. However,
Weitzman (1977)
affirmed that these genera cannot be distinguished either phylogentically or typologically as separate taxa because, as
Böhlke (1955)
pointed out, there are species which are intermediate in their caudalfin squamation. Even so, this author recognized his new species as belonging to
Hyphessobrycon
rather than
Hemigrammus
, employing a practical, typological procedure (amount of caudal-fin squamation), and based on the traditional definitions of these genera provided by Ellis (in
Eigenmann, 1918
).
Hyphessobrycon otrynus
shares with
H. diancistrus
the identical color pattern and the presence of two large hooks on each side of the caudal fin, which are indicative of a close relationship. Thus, we follow
Weitzman (1977)
in recognizing this new species in the genus
Hyphessobrycon
, emphasizing the putatively close relationship between these species.
Weitzman (1977)
discussed that large anal-fin hooks are known in other species of
Hyphessobrycon
and
Hemigrammus
and cited
Hemigrammus occelifer
as an example, but emphasized that its unique and fairly large hook on each side of the anal fin, along with the several morphometric and meristic differences, indicate that there is no phylogenetic or typological proximity between
H. occelifer
and his
H. diancistrus
.
Moenkhausia ceros
Eigenmann (1908)
was described as having the third anal-fin ray of males provided with a large retrorse hooks on each side. Examination of the
holotype
of
M. ceros
confirmed that this species can be promptly distinguished from
H. otrynus
by presenting a single developed bony hook on each side of the anal fin (vs. two large bony hooks), by presenting a complete lateral line (vs. incomplete), and by a distinct caudal-fin color pattern, with the middle rays of caudal fin black pigmented instead of the black blotched caudal-fin lobes, as observed in the latter species.
The occurrence of two large anal-fin hooks was discussed by
Weitzman (1977)
as being restricted to
Tyttobrycon hamatus
and
Hyphessobrycon diancistrus
. Notwithstanding this comment, this author enumerated several distinguishing features between these species and stated that sharing anal-fin hooks is most likely a case of convergence.
Hyphessobrycon otrynus
displays a reduction to the number of the two anterior unbranched plus eight branched dorsal-fin rays, considering that the usual characid dorsal-finray count is two anterior unbranched rays plus nine branched rays (
Malabarba & Weitzman, 2003
). The presence of two branched plus eight unbranched dorsal-fin rays is only scarcely distributed among individuals of a few species of
Hyphessobrycon
(
e.g.
Hyphessobrycon eilyos
).
Malabarba & Weitzman (2003)
hypothesized that eight branched dorsal-fin rays and four teeth in the inner row of the premaxillary bones are synapomorphies for a group of characids that they termed Clade A. This clade is formed by the subfamily
Glandulocaudinae
and the genera
Cyanocharax
,
Attonitus
,
Boehlkea
,
Bryconacidnus
,
Bryconamericus
,
Caiapobrycon
,
Ceratobranchia
,
Creagrutus
,
Hemibrycon
,
Hypobrycon
,
Knodus
,
Microgenys
,
Monotocheirodon
,
Odontostoechus
,
Othonocheirodus
,
Piabarchus
,
Piabina
,
Rhynobrycon
, and
Rhinopetitia
. Comparisons with representative species of Clade A revealed no further similarities among these species and
H. otrynus
, and the common presence of only eight branched dorsal-fin rays is most likely homoplastic, possibly indicating the paedomorphic nature of this reduction in
H. otrynus
.
Comparative material examined.
Bryconamericus straemineus
, LBP 4978,
Creagrutus varii
,
LIRP
4342,
holotype
.
Hemigrammus marginatus
, LBP 268.
Hyphessobrycon diancistrus
,
MZUSP
13179,
paratype
,
Moenkhausia ceros
,
MCZ
49161,
holotype
.
Piabina argentea
LBP3886.