A revision of the cis-andean species of the genus Brycon Müller & Troschel (Characiformes: Characidae)
Author
Lima, Flávio C. T.
text
Zootaxa
2017
4222
1
1
189
journal article
37268
10.5281/zenodo.257769
9ea59a17-588e-4af1-8c0d-ebcd50ad0395
1175-5326
257769
F0EC0A87-B1EE-4B5C-8F53-77A7EEA75F3A
Brycon coquenani
Steindachner, 1917
(
Fig. 21
)
Brycon coquenani
Steindachner, 1917
: 37
–38, pl. 1, figs. 1–2 (Type locality, “ Coquenanflusse in Venezuela”).
Diagnosis.
Brycon coquenani
can be distinguished from all remaining cis-andean
Brycon
species, except
B. stolzmanni
,
B. coxeyi
,
B. devillei
,
B. insignis
,
B. vermelha
,
Brycon howesi
,
B. dulcis
,
B. ferox
,
Brycon vonoi
,
B. opalinus
, and
B. nattereri
, by possessing a color pattern composed by a humeral blotch and a caudal peduncle blotch (vs. body stripes and caudal/anal fin color markings present; see
Fig. 5
).
Brycon coquenani
can be distinguished from all these species, except
B. insignis
,
B. vermelha
, and
B. howesi
, by possessing a fifth infraorbital bone wider than high (vs. fifth infraorbital bone about as wide as high; see
Fig. 6
).
Brycon coquenani
can be distinguished from these species by possessing pointed, tri- to tetracuspidate dentary teeth, with lateral cusps poorly developed (vs. pointed tri- to pentacuspidate dentary teeth, with moderately developed lateral cusps in
B. insignis
,
B. vermelha
, and
B. howesi
), and by mature males displaying hooks in all rayed fins (vs. hooks present generally only in the anal-fin, rarely also in the pelvic-fins in mature males in
B
.
insignis
, and
B
.
howesi
, and not present in
B
.
vermelha
).
Description.
Morphometric data are presented in
Table 4
. Relatively small-sized species, largest examined specimen
170.6 mm
SL. Body moderately slender. Largest body height slightly ahead of dorsal-fin origin. Dorsal body profile slightly convex from upper lip margin to vertical through anterior naris, slightly concave from latter point to basis of supraoccipital process, and moderately convex from latter point to dorsal-fin origin, straight along dorsal-fin basis, straight to slightly convex from dorsal-fin terminus to adipose-fin origin. Dorsal profile of caudal peduncle slightly concave. Ventral profile slightly convex from lower lip to pelvic-fin insertion, straight to slightly convex from this point to anal-fin origin and approximately straight along anal-fin base. Ventral profile of caudal peduncle slightly concave.
Head profile slightly acute anteriorly, mouth terminal. Maxillary extending posteriorly to vertical slightly anterior to middle of pupil. Adipose eyelid well developed. Premaxillary teeth in three rows; teeth of third row largest. Small specimens (<
84.2 mm
SL) with gaps (diastemas) between teeth. Eight (1), 9 (5), 10 (2), or 11 (1) unicuspidate teeth in outer series. Three (2), 4 (2), or 5 (1) tri- to pentacuspidate teeth in second, inner premaxillary row, plus 1(1), 2 (3), or 3 (1) tricuspidate teeth between the first and third rows. Two teeth in third premaxillary row, medial teeth largest, pentacuspidate, symphyseal teeth smaller, tricuspidate. Maxillary with distal portion expanded and rounded in profile. Twenty-five to 31 maxillary teeth, unicuspidate, slightly smaller than teeth of first premaxillary row. Dentary with 8 (1), 9 (2), 10 (1), 11 (3), or 12 (2) teeth in main series. Anterior four dentary teeth assymetrical, considerably larger than remaining teeth, tri- to tetracuspidate. Remaining dentary teeth progressivelly smaller, unicuspidate. Inner (lingual) series consisting of a single unicuspid symphyseal tooth, considerably smaller than teeth of main series anterior to it, plus a row of small, unicuspidate teeth. All teeth with well-developed, pointed central cusp, remaining cusps, when present, poorly developed or vestigial.
TABLE 4.
Morphometric data of
Brycon coquenani
(A: lectotype, NMW 62702).
A |
n |
Range |
Mean |
Standard length (SL) |
170.6 |
9 |
72.9–170.6 |
- |
Percentages of standard length |
Depth at dorsal-fin origin |
25.8 |
9 |
17.3–25.8 |
21.9 |
Snout to dorsal-fin origin |
56.9 |
9 |
54.3–56.9 |
55.9 |
Dorsal-fin base length |
11.4 |
9 |
11.1–14.8 |
12.5 |
Posterior terminus of dorsal fin to adipose fin |
21.7 |
9 |
17.0–21.7 |
18.6 |
Posterior terminus of dorsal fin to hypural joint |
33.1 |
9 |
31.6–34.3 |
32.9 |
Snout to pelvic-fin insertion |
50.7 |
9 |
50.7–56.2 |
54.3 |
Snout to anal-fin origin |
65.4 |
9 |
65.4–69.5 |
68.1 |
Anal-fin base length |
23.1 |
9 |
21.1–25.5 |
22.9 |
Caudal peduncle length |
15.2 |
9 |
12.2–15.2 |
14.4 |
Dorsal-fin height |
18.7 |
1 |
18.7 |
- |
Pectoral-fin length |
15.8 |
1 |
15.8 |
- |
Caudal peduncle depth |
7.7 |
9 |
6.5–7.7 |
6.8 |
Head length |
30.9 |
9 |
30.9–34.3 |
32.8 |
Percentages of head length |
Head height |
60.6 |
9 |
59.8–64.9 |
61.4 |
Snout length |
29.4 |
9 |
27.4–31.8 |
29.3 |
Upper jaw length |
46.8 |
9 |
46.8–51.7 |
49.7 |
Horizontal eye diameter |
23.1 |
9 |
23.1–26.6 |
25.7 |
Post-orbital length |
51.3 |
9 |
40.4–51.3 |
44.3 |
Least interorbital width |
27.1 |
9 |
18.0–27.1 |
20.6 |
Scales cycloid. Lateral line complete, from supracleithrum to caudal-fin base. Forty-four (1), 46 (3), 47 (2), or 48 (3) scales in lateral line series; laterosensory tube simple, straight or deflected downwards. Horizontal scale rows between dorsal-fin origin and lateral line 8 (6), or 9 (3). Horizontal scale rows between lateral line and pelvicfin 4. Circumpeduncular scales 17 (2), or 18 (1).
Dorsal-fin rays ii, 8 (2) or 9 (9). Dorsal fin origin slightly ahead from middle of SL. Dorsal fin displaying numerous (c. 15–30 per fin-ray main branch) small hooks on last unbranched and posterior main branch of all branched rays in one specimen (lectotype, NMW
62702, 170.6 mm
SL). Anal-fin rays iii (not including first, small unbranched ray only visible in the cs specimen), 18 (1), 19 (2), 21 (3), 22 (4), 23 (2), or 24 (2). Last unbranched and anterior 2–3 branched anal-fin rays longer, remaining rays progressively shorter towards anal-fin end. Anal fin displaying numerous (c. 20–30 per fin-ray main branch) small hooks associated with dense, gelatinous tissue on last unbranched and posterior main branch branched rays to antepenultimate branched ray in one specimen (lectotype, NMW
62702, 170.6 mm
SL). Sheath of scales composed of a single series composed by 15 rectangular scales, covering basis of anal-fin rays. Pectoral-fin rays i, 11 (2), 12 (4), or 13 (3). Branched pectoral-fin rays with minute hooks (c. 10 per branch) on distal portion of posterior ray branches in one specimen (lectotype, NMW
62702, 170.6 mm
SL). Pelvic-fin rays i,7. Branched pelvic-fin rays with minute hooks (c.10–20 per branch) on distal portion of posterior ray branches in one specimen (lectotype, NMW
62702, 170.6 mm
SL). Main caudal-fin rays 10/9. Small hooks (c. 5–10 per ray branch) on distal portion of inner caudal-fin rays in one specimen (lectotype, NMW
62702, 170.6 mm
SL). Caudal fin forked, lobes rounded.
FIGURE 21.
Brycon coquenani
, lectotype, NMW 62702, 170.6 mm SL: Venezuela, Bolívar, Río Kukenan.
Coloration in alcohol.
Color description based on the
lectotype
, NMW 62702;
paralectotypes
too faded to allow an accurate color description. Top of head, snout, supraorbital, sixth infraorbital bone, and dorsal portion of body dark brown. Dentary, maxillary, first, second, and upper portion of fifth infraorbital bone, gular area, and ventral portion of body cream-colored. Third, fourth, lower portion fifth infraorbital bones, and opercle silvery, with a brownish tinge. Humeral blotch present, relatively inconspicuous, rounded, extending from first through third lateral line scales. Lateral portions of body cream-colored, with a silvery hue. Caudal peduncle blotch present, conspicuous, rounded, extending throughout 6 last lateral line scales into basis of 4 innermost caudal-fin rays. Caudal, anal and dorsal-fins with numerous small dark chromatophores scattered over interradial membranes. Pectoral and pelvic-fins with relatively few dark chromatophores on interradial membranes. Adipose fin light brown.
Common name.
“Aruma”. This common name, mentioned by
Steindachner (1917: 37)
, was recorded by the collector of the
type
material, John Haseman. In an undated manuscript authored by
Haseman
, entitled “
Zoogeographical
expedition to northeastern
South
America”, he mentioned (p. 44) “aruma” as the “native” name of an undescribed species of
Brycon
collected in the
Río
Kukenan
.
The Amerindians which helped Haseman during his expedition into the tepuis of
northern Roraima
state in
Brazil
and southern
Bolívar
state in
Venezuela
belonged to the Arekuna (= Taulipang), so it can be assumed that this common name is originated from this language.
Sexual dimorphism.
The lectotype (NMW
62702, 170.6 mm
SL) possess numerous small hooks over all rayed fins, including the caudal-fin. However, a dissection was not performed to confirm the specimen’s sex.
Distribution.
Brycon coquenani
is only known from the upper
Rio
Kukenan (“Coquenanflusse”), a tributary of the upper
Río
Caroní,
Río
Orinoco basin, estado
Bolívar
,
Venezuela
(
Fig. 20
). The exact locality of
Brycon coquenani
is not known but according to the narrative of Haseman’s travel in the region referred above, the
type
series was collected in the
Rio
Kukenan at its valley between the mount
Roraima
and the Cerro Kukenan, below the “Moromelu Falls” (not located).
Remarks.
Steindachner (1917: 37–38)
described the species based on a syntypical series of “11 ... juveniles and a larger, very well preserved exemplar
210 mm
long” (our translation). We have examined the syntypical series of
Brycon coquenani
at the NMW. The largest specimen, NMW 62702, is herein designated as the lectotype of the species. The remaining, smaller syntypes, NMW 62703 (10 specimens) became, consequently, paralectotypes.
The
lectotype
is in very good condition, except for missing some scales and for having the top of head bruised, apparently by
Steindachner
himself, presumably for the examination of the fontanel.
In
spite of relatively recent collecting efforts in the upper
Río
Caroní basin, including the
Río
Kukenan, so far no additional specimens of the species were obtained (Lasso, 1990; Lasso
et al.
, 1990).
Material
examined.
Type
material:
NMW
62702 (
1, 170.6 mm
SL):
Venezuela
, Estado
Bolívar
,
Río Kukenan
,
upper Río Caroní
basin,
Gran Sabana
, approximately
5°12’N
,
60°46’W
;
J.D. Haseman
,
April 1913
.
Lectotype
of
Brycon coquenani
Steindachner
, by present designation.
NMW
62703 (10,
64.7–84.2 mm
SL): same data as lectotype
. Paralectotypes of
Brycon coquenani
.