Redescription of Odontostilbe pulchra (Gill, 1858) (Teleostei: Characidae: Cheirodontinae), and description of two new species from the río Orinoco basin
Author
Bührnheim, Cristina M.
Author
Malabarba, Luiz R.
text
Neotropical Ichthyology
2007
2007-03-31
5
1
1
20
http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252007000100001&lng=en&tlng=en
journal article
5735
10.1590/S1679-62252007000100001
be160b91-029a-4201-9739-ab3e8a242547
1982-0224
4567004
Odontostilbe splendida
,
new species
Fig. 12
Holotype
.
ANSP 181040
,
1 male
(
32.7 mm
SL),
Colombia
,
Meta
,
río Negrito
at bridge at
La Balsa
,
Meta
drainage,
J. E. Böhlke
et al
.,
27 March 1975
.
Paratypes
.
ANSP 181041
,
30
m, (8x of 30), (
8 males
29.4-36.4 mm
SL,
1 male
34.7 mm
SL c&s,
20 females
31.3-41.6 mm
SL,
1 female
32.1mm
SL c&s), same data as holotype
.
MCP
38862,
27
(
13 males
28.9-33.6 mm
SL,
1 male
29.5 mm
SL c&s, 13 unsexed
28.5-34.4 mm
SL), same data as holotype
, formerly
ANSP 139572
.
MCNG 54519
,
13
(
7 males
29.2-33.2 mm
SL, 6 unsexed
30.1-34.4 mm
SL), same data as holotype
.
MBUCV 32890
,
13
(
7 males
29.3-32.9 mm
SL, 6 unsexed
25.8-32.3 mm
SL), same data as holotype
.
ICNMHN 14168
,
13
(
7 males
29.0- 33.0 mm SL, 6 unsexed 31.0-
32.8 mm
SL), same data as holotype
.
INPA 25173
,
13
(
7 males
29.5-32.2 mm
SL, 6 unsexed 29.7-34.2), same data as holotype
.
Non types. Río
Meta
basin,
COLOMBIA
,
META
:
MHNG 2512.93
,
3
(unsexed 22.9-27.0 mm SL),
río Humadea
, near
El Merey
basin of río
Meta
.
ANSP 139484
,
7
(
2 males
32.8-33.9 mm
SL, 5 unsexed
29.7-33.6 mm
SL), confluence of
río Guayariba
and
río Metica.
Río
Apure
basin,
VENEZUELA
,
GUARICO
:
ANSP 181137
,
50
(
1 male
31.1 mm
SL, 49 unsexed
19.2-37.5 mm
SL), tributary of río
Guarico
,
3 km
S of Calabozo
on federal highway no. 2, formerly
ANSP 139696
.
MCP
14971,
11
unsexed
17.1-31.7 mm
SL, río
Apure
,
San Fernando
de
Apure
, formerly
ANSP 150111
.
VENEZUELA
,
PORTUGUESA
:
USNM 349419
,
7
unsexed 29.9- 33.0 mm SL,
río Las Marias
, quebrada
Seca
(town) approximately 45 min. upstream by car from hwy. 5, 22
Km
NNW Guanare.
Río Orinoco
basin,
VENEZUELA
,
BOLIVAR
:
ANSP 181136
,
30
(
1 male
32.8 mm
SL, 29 unsexed
26.2-33.5 mm
SL), caño
Caiman
, at crossing of
Caicara - Puerto Ayacucho
hwy,
19.2 km
W of Ciudad Bolivar-Caicara
highway, formerly
ANSP 159904
.
Diagnosis.
The anterior position of the adipose fin, at vertical through last 2
nd
or 3
rd
anal-fin ray insertions in
O. splendida
(
Fig. 12
) is noticeably distinct from all other
Odontostilbe
species, including the sympatric
O. pulchra
(
Fig. 1
) and
O. pao
(
Fig. 23
), in which the adipose fin is positioned at vertical through last anal-fin ray insertion.
Odontostilbe splendida
further differs from
O. pulchra
by a group of morphometric characters in males: snout pointed and longer in
O. splendida
(24.1-26.9% HL)
vs
short and blunt in
O. pulchra
(18.0-26.0% HL) (
Fig. 5
), shorter pectoral-fin length (20.9-23.5% SL in
O. splendida
vs
21.3-26.4% SL in
O. pulchra
) (
Fig. 13
), smaller anal-fin base (24.9-26.8% SL
vs
26.0-31.4% SL) (
Fig. 14
), shorter caudal peduncle length (11.5- 13.0% SL
vs
12.5-16.0% SL) (
Fig. 15
), longer snout-pelvic fin origin distance (45.1-48.7% SL
vs
42.3-47.9% SL) (
Fig. 16
), and longersnout-analfinorigindistance (63.7-68.6% SL
vs
58.6-64.0% SL) (
Fig. 17
). Additionally, mature males of
O. splendida
are remarkably distinguished by the presence of hooks on 1
st
to 6
th-
7
th
anal-fin rays,
vs
hooks on 1
st
to 22
nd
anal-fin branched rays in
O. pulchra
. Mature males of
O. splendida
usually have the 2
nd
unbranched dorsal-fin ray elongate, not present in
O. pulchra
. Females and immature specimens, and not well-developed males of
O. splendida
and
O. pulchra
, have overlapping ranges in many of the ratios cited above, and can be differentiated by the following characters:(1) presence of 3-4 (mostly 3) maxillary teeth in
O. splendida
,
vs
2-3 (mostly 2) in
O. pulchra
; 36 lateral line scales (one specimen 35) in
O. splendida
vs
33-37, mostly 34-35 lateral line scales in
O. pulchra
.
The number of gill rakers counts on lower branch differ
O. splendida
(averaging 11) from
O. fugitiva
(usually 12) (
Fig. 18
).
Description.
Morphometric data are given in
Table 2
. Largest male
36.4 mm
in.SL, largest female
41.6 mm
in SL. Body elongate and compressed. Body of males slightly more compressed and elongate than females. Greatest body depth at dorsal-fin origin. Snout short, somewhat pointed in males. Head profile pointed, gently convex to straight from snout to posterior tip of supraoccipital bone. Predorsal profile slightly convex to straight between posterior tip of supraoccipital bone and dorsal-fin origin, straight on dorsal-fin base, and then slightly convex to straight from end of dorsal-fin base to caudal peduncle. Ventral profile convex from mouth tip to anal-fin origin. Analfin base straight. Caudal peduncle slightly longer than deep.
Head relatively small. Posterior margin of opercle sinusoidal with upper portion concave and lower portion convex. Mouth terminal. Maxilla obliquely positioned ending at vertical through anterior border of eye, and at horizontal on inferior border of eye. Premaxillary teeth 5-6, bearing 8-11 cusps; central cusp longest (
Fig. 19
). Maxilla with 3-4 (mainly 3) teeth bearing 5-9 cusps, decreasing cusp number toward posterior tip of maxilla. Dentary teeth 9-10, gradually decreasing in size, anterior 5-6 teeth large bearing 7-8 cusps, 1 medium-sized tooth with 5-6 cusps, and posterior teeth small, conic or with 2-5 cusps. Smaller cusps of dentary teeth overlap cusps of adjacent tooth.
Fig. 12.
Holotype of
Odontostilbe splendida
, ANSP
181040, male 32.7 mm SL (top), and paratype ANSP 181041, female 32.1 mm SL (bottom).
Dorsal-fin rays
ii,9
(31). Dorsal-fin origin slightly posterior to mid body length, and slightly posterior to pelvic-fin origin. Second unbranched dorsal-fin ray slightly elongate in some males (not in
holotype
), extending beyond dorsal-fin distal profile. Anal-fin rays iv(6), or
v
(25),
19
(9), 20(16), 21(5), or 22(1). Anal-fin distal border concave, anterior 6-7 branched
rays longest. Pectoral-fin rays i(31), 9(2),
10
(9), 11(16), or 12(3). Pelvic-fin rays i(31), 6(1), or
7
(30). Unbranched pelvic-fin ray longest ray in mature males, extending beyond origin of anal fin. Lateral skin border of unbranched pectoral-fin ray and unbranched pelvic-fin ray slight thickened in males. Principal caudal-fin rays 19(31). Procurrent caudal-fin rays: dorsal 10(1), 11(4), 12(14),
13
(9), or 14(3), ventral 9(3), 10(17),
11
(10), or 12(1). Anterior 1 or 2 ventral procurrent caudal-fin rays sometimes laterally expanded or bifurcated. Caudal-fin ray flaps ventrally on 4
th-
8
th
branched rays of upper lobe, dorsally on 13
th
-16
th
branched rays of lower lobe. Adipose-fin at vertical through last 2
nd
or 3
rd
anal-fin ray insertions.
Fig. 16.
Snout-pelvic fin origin as a function of standard length for males of
Odontostilbe pulchra
, against
O. splendida
.
Fig. 13.
Pectoral-fin length as a function of standard length for males of
Odontostilbe pulchra
, against
O. splendida
.
Fig. 17.
Snout-anal fin origin as a function of standard length for males of
Odontostilbe pulchra
, against
O. splendida
.
Fig. 14.
Anal-fin base as a function of standard length for males of
Odontostilbe pulchra
, against
O. splendida
.
Fig. 18.
Lower gill rakers counts of
Odontostilbe pulchra
,
Odontostilbe fugitiva
(data from Bührnheim & Malabarba, 2006), and of two new species
Odontostilbe splendida
, and
Odontostilbe pao
.
Fig. 15.
Caudal peduncle length as a function of standard length for males of
Odontostilbe pulchra
, against
O. splendida
.
Fig. 19.
Dentition of
Odontostilbe splendida
, paratype ANSP 181041, female 32.1 mm SL: right side premaxilla (top), maxilla (middle), and dentary (bottom), lateral view. Scanning electron micrographs (SEM).
Fig. 20.
First gill arch of
Odontostilbe splendida
, MCP
38862, male 29.7 mm SL: left side, lateral view, showing gill gland (top), in detail gill rakers on upper branchial branch (middle), and gill rakers on lower branchial branch (bottom). Scanning electron micrographs (SEM).
Males with acute retrorse hooks on posterior border of pelvic- and anal-fin rays. One or two paired or unpaired hooks per segment of lepidotrichia, at distal half-length of last unbranched anal-fin ray, and 1
st
to 6
th-
7
th
branched anal-fin rays. One or two unpaired long hooks per segment of lepidotrichia along almost entire length of 1
st
to 7
th
branched pelvic-fin rays, reaching distal tip of fin ray (except on 1
st
branched pelvic-fin ray, on midlength portion). One or two unpaired hooks per segment of lepidotrichia on anterior border of branchings of pelvic- and anal-fin rays.
Scales cycloid: lateral line complete 35(1), or
36
(26); predorsal row
10
(10), or 11(20); scale rows between lateral line and dorsalfin origin
6
(28), or 7(2); scale rows between lateral line and analfin origin
4
(15), or 5(15); scale rows around caudal peduncle
14
(29). Triangular modified scale on pelvic-fin base extends posterior covering 2-3 scales. Scales on anal-fin base
6
or 7.
Cleared and stained specimens (3), and radiographs (8): supraneurals 4; precaudal vertebrae, including Weberian apparatus, 16(3), or 17(8); caudal vertebrae 17(3), 18(7), or 19(1); gill rakers, upper 5(1), or 6(2), lower 10, 11, or 12 (2-3 on hypobranchial). Alcohol specimens (22): gill rakers, upper 5(2),
6
(18), or 7(2), lower
11
(21), or 12(1). Upper gill rakers with none to 3 denticles on anterolateral border; lower gill rakers with 1-4 recurved denticles on anterolateral border; and posteriormost lower gill raker with none to 7 recurved denticles on posterior border, and 3 denticles on anterior border (
Fig. 20
). Denticulation mainly on basal portion of gill rakers.
Color in alcohol.
General ground body color pale yellow or pale orange. Dorsal part of body darker with chromatophores more concentrate on scales border, from head to caudal peduncle. Dark chromatophores along all dorsal-fin rays. Pectoral fin with chromatophores along 1
st
unbranched pectoralfin ray and 1
st
branched fin rays. Pelvic fin clear.Anal fin with dark chromatophores on central branched anal-fin rays, except at tips of last unbranched fin rays and 1
st
branched fin ray; hyaline in
holotype
. Adipose fin clear. Caudal fin almost entirely covered with diffuse dark chromatophores along fin rays, except clear areas on base of caudal-fin lobes just behind caudal-fin spot (chromatophores very faded in type material). Rounded brown to black spot on base of caudal fin, usually reaching upper border of caudal peduncle.
Fig. 21.
Caudal peduncle length as a function of standard length for males against females of
Odontostilbe splendida
.
Dark chromatophores on snout, upper lip, anteriormost portion of maxilla, and 1
st
to 2
nd
infraorbitals. Top of head on frontals and parietals pigmented, deep-lying dark chromatophores over brain membranes below frontals and parietals, and fontanels. Body with faint dark and silver midlateral stripe, beginning behind pseudotympanum, above lateral line, and reaching caudal spot. Guanine on eye iris, opercle, isthmus, and 2
nd
to 5
th
infraorbital. Presence or not of scattered chromatophores on pseudotympanum area. Below lateral line, belly faint usually unpigmented, chromatophores above anal-fin base area forming 10 to 11 chevron shaped markings (faint scattered chromatophores in
type
material).
Sexual dimorphism.
Males have hooks on anal and pelvicfin rays, and slight elongation of dorsal- and pelvic-fin rays, in contrast to the absence of these features in females (see description). A gill gland (Burns & Weitzman, 1996) is found in mature males of
Odontostilbe splendida
. The gill gland is present on the first gill arch, including about 7 to 9 anterior branchial filaments (
Fig. 20
). Males usually have longer snout length, and caudal peduncle length (
Fig. 21
).
Distribution.
Río Orinoco basin (
Fig. 22
).
Etymology.
Refers to the Latin word
splendidus
, meaning splendid, grand, admirable.
Ecological notes.
Field notes of
type
material indicate bottom with mud and sand, and water depth nearly
3 feet
.