Revision of the South American genus Tetragonopterus Cuvier, 1816 (Teleostei: Characidae) with description of four new species
Author
Silva, Gabriel S. C.
Author
Melo, Bruno F.
Author
Oliveira, Claudio
Author
Benine, Ricardo C.
text
Zootaxa
2016
4200
1
1
46
journal article
37756
10.11646/zootaxa.4200.1.1
834295d1-63b4-4951-a5ea-f2d3ec0228f3
1175-5326
177598
911ECACD-8903-405E-AAA4-8300901D69C7
Tetragonopterus georgiae
(
Géry, 1965
)
,
new combination
(
Fig. 5
,
Table 4
)
Moenkhausia georgiae
Géry, 1965
: 104
(original description;
type
locality: “between ‘Saut-Chien’ and ‘Saut-Topi-Topi’, middle Mana River, French
Guyana
);
Géry, 1977
: 443
(in key to the genus
Moenkhausia
).
Vari
et al.
, 2009
: 32
(listed;
Guiana
shield);
Mol
et al.
, 2012
: 270
(listed;
Suriname
).
Melo
et al.
, 2016
: 709
–717 (molecular phylogeny).
Diagnosis.
Tetragonopterus georgiae
is distinguished from all congeners, except
T. rarus
, by having 4.5–5.5 scale rows between lateral line and pelvic fin origin (
vs.
3.5 scale rows). It can be diagnosed from
T. rarus
by the absence of longitudinal dark stripes on the trunk (
vs.
the presence of stripes).
Tetragonopterus georgiae
differs from
T. anostomus
,
T. denticulatus
,
T. kuluene
and
T. juruena
by having 4 principal teeth in dentary (
vs.
5–6) and by having larger and more robust teeth (
vs.
thinner and sharper teeth).
Tetragonopterus georgiae
differs from
T. anostomus
and
T. kuluene
by the presence of two conspicuous humeral marks (
vs.
only one inconspicuous humeral mark); it also differs from
T. anostomus
by having a terminal mouth (
vs.
subsuperior mouth).
Tetragonopterus georgiae
differs from
T. anostomus
and
T. araguaiensis
by the presence of 10–12 gill rakers on the upper limb (
vs.
17–20) and 7–8 gill rakers on the lower limb (
vs.
10–12) of the first gill arch.
Tetragonopterus georgiae
also differs from
T. argenteus
by the presence of 8 predorsal scales (
vs.
11–17), and from
T. carvalhoi
by the presence of a rounded dark mark on the caudal peduncle (
vs.
a lozenge-shaped dark mark).
Tetragonopterus georgiae
differs from
T. ommatus
by having 1–4 teeth on maxilla (
vs.
7–8) and by having a dark mark centered on caudal peduncle (
vs.
mark limited to the posterior portion of the caudal peduncle).
Description.
Morphometric data summarized in
Table 4
. Body shape compressed and deep. Greatest body depth at dorsal-fin origin. Dorsal profile slightly convex between tip of snout and vertical through middle of orbit; slightly concave from this point to end of occipital process; convex from tip of occipital process to dorsal-fin origin; then slightly convex between dorsal-fin origin and rear of adipose fin. Prepelvic region transversely flattened with distinct, longitudinally aligned lateral keels. Ventral profile of body slightly convex from lower lip to slightly behind vertical through pectoral-fin origin; convex from that point to anal-fin origin; straight along base of anal fin. Caudal peduncle with dorsal and ventral profiles slightly concaves.
TABLE 4.
Morphometric data for
Tetragonopterus georgiae
(n=22). Range includes paratypes.
Range |
Mean |
Standard length (mm) |
33.7–68.0 |
56.8 |
Percentages of standard length |
Greatest depth |
44.7–53.4 |
48.5 |
Predorsal length |
49.7–53.3 |
51.4 |
Prepectoral length |
25.5–29.6 |
27.2 |
Prepelvic length |
45.8–54.8 |
51.1 |
Preanal length |
64.1–70.8 |
67.6 |
Caudal peduncle depth |
9.5–11.7 |
10.9 |
Caudal peduncle length |
6.5–11.7 |
1.32 |
Pectoral-fin length |
22.1–26.0 |
24.6 |
Pelvic-fin length |
17.5–20.0 |
18.9 |
Dorsal-fin length |
31.4–39.9 |
35.3 |
Length of dorsal-fin base |
15.5–18.0 |
16.8 |
Anal-fin length |
18.1–22.6 |
20.1 |
Length of anal-fin base |
30.4–34.0 |
32.4 |
Distance from eye to dorsal-fin origin |
40.1–48.9 |
46.6 |
Distance from dorsal-fin origin to caudal-fin base |
54.6–60.4 |
57.4 |
Head length |
26.5–29.8 |
28.0 |
Head depth |
22.5–20.7 |
24.8 |
Percentages of head length |
Snout length |
13–22 |
16.4 |
Maxillary length |
38–46 |
41.4 |
Horizontal orbital diameter |
47–57 |
50.8 |
Least interorbital width |
27–32 |
30.6 |
FIGURE 5.
Tetragonopterus georgiae
.
(a–b)
Moenkhausia georgiae
, ANSP 94708, paratype, 58.3 mm SL, French Guyana, Litany river, upper Marowijne river basin; c)
T. georgiae
, Suriname, live specimen. Photos (a–b) by K. Luckenbill and (c) by R. Covain.
Olfactory lamellae 20 (3), 22 (2), 23 (1), 24 (1) or 25 (3). Mouth terminal. Upper and lower jaws of similar size. Premaxilla in two rows of relatively robust teeth. Outer row with 4 (7), 5 (9) or 6 (1) teeth with three cusps, central cusps longest. Inner row with 5 (14) or 6 (1) teeth with three or five cusps, central cusps twice as long as the lateral cusps. Maxilla with 2 (7) or 3 (8) either conic or tricuspidate teeth. Dentary bearing 4 (16) or 5 (1) anteriormost teeth with 3 to 5 cusps.
Dorsal-fin rays ii,9 (18). First unbranched ray shorter than second one. Dorsal-fin origin anterior to middle of body in SL. Anal-fin rays iv,23 (6), iv,25 (4), iv,26 (6) or iv,27 (1); posterior unbranched rays and anterior branched rays slightly longer than following rays. Anal-fin origin situated posterior to vertical line through posterior most branched dorsal-fin rays. Pelvic-fin rays i,7 (18); origin situated anterior to vertical line through dorsal-fin origin; tip of adpressed pelvic fin reaching first unbranched anal-fin ray. Pectoral-fin rays i,11 (1) i,12 (1), i,13 (10), i,14 (3) or i,15 (2). Caudal fin forked.
Scales large and cycloid. Lateral line complete and slightly bent downward anteriorly. Longitudinal scales 31 (5), 32 (8), 33 (4) or 34 (2). Scale rows between lateral line and dorsal-fin origin 6 (17) or 7 (1). Scale rows between lateral line and pelvic-fin origin 4.5 (18). Predorsal scales 7 to 9. Scale rows around caudal peduncle 13 (3) or 14 (15). Anal-fin base covered by a single row of small scales. Caudal-fin base covered by small scales in both lobes; such scales smaller than those covering lateral surface of body.
First gill arch with 7 (3), 8 (13) or 9 (1) gill rakers on upper limb and 11 (4), 12 (11) or 13 (1) gill rakers on lower limb. Total vertebrae 29, precaudal vertebrae 12, intermediate vertebrae 2 and caudal vertebrae 17 (3 c&s). Supraneurals 3 (2 c&s).
Color in alcohol.
General body color yellowish. Dorsal portions of head and body darkly pigmented. Dorsolateral portion of body with few minute chromatophores along distal margin of scales; scales of ventrolateral portion of body unpigmented. Opercular and infraorbital bones silvery. Two conspicuous vertical dark humeral marks separated by one scale, with anterior mark more evident. Anterior humeral mark extending over four horizontal scale rows above and one horizontal scale rows below lateral line. Posterior humeral mark located over three horizontal scales rows above lateral line. Caudal peduncle with a distinctly rounded dark mark. Midlateral silvery stripe broad, extending from supracleithrum to caudal peduncle. Anal, pelvic, and dorsal fins hyaline, with chromatophores concentrated at distal portions of the rays. Adipose fin hyaline covered by small chromatophores distally (
Fig. 5
a).
Sexual dimorphism.
None observed.
Distribution.
Tetragonopterus georgiae
is known from Siparuni, Rupununi and Potaro rivers of the
Essequibo
basin in
Guyana
; Río Nichare, Orinoco basin in
Venezuela
and the upper Rio Paru, a left tributary of the Amazon basin in northern
Brazil
.
Vari
et al.
(2009)
reported
Moenkhausia georgiae
(=
T. georgiae
) in French
Guyana
and
Suriname
.
Mol
et al.
(2012)
listed
M. georgiae
for the Corantijn,
Nickerie
, Coppename,
Suriname
, and
Marowijne
River basins of
Suriname
.
Le Bail
et al.
(2012)
reported
M. georgiae
for the Mana, Sinnamary, Comté, Orapu, Approuague, and Oyapock rivers of French
Guyana
at the boundary with
Amapá
in
Brazil
. We herein recorded
T. georgiae
for
Venezuela
at the Río Cuyuni (a tributary of
Essequibo
River) and Río Nichare (a tributary of Río Caura), the latter record extending the distribution of the species to the Río Orinoco basin. We also recorded
T. georgiae
in the upper Rio Paru, a left-margin tributary of the rio
Amazonas
with headwaters at the
Guiana
Shield (
Fig. 2
a).
Remarks.
Eigenmann’s (1917) definition of
Moenkhausia
is based on the presence of two parallel rows of premaxillary teeth, five or more teeth in the inner premaxillary tooth row, a completely pored lateral line, and the presence of scales covering the lobes of the caudal fin. Although
Moenkhausia
and
Tetragonopterus
are phenotypically similar in body shape, the later usually has a downward curved lateral line along with other apomorphic characters (
Mirande 2010
;
Melo
et al.
2011
).
Géry (1965)
described
M. georgiae
and allocated it in
Moenkhausia
due to the non-proeminent curvature of the anterior portion of the lateral line. Later,
Géry (1977)
cited
M. georgiae
as “a species strongly resembling
Tetragonopterus chalceus
. Four examined
paratypes
(ANSP 94708, ANSP
112246
, ANSP 139714) (
Fig. 5
a-b) have three supraneurals and a branched laterosensory canal in the sixth infraorbital, synapomorphies previously proposed for
Tetragonopterus
(
Melo
et al.
2011
)
. The later authors discuss that such features are not present in any other species of
Moenkhausia
(including its
type
species,
M. xinguensis
), except
M. georgiae
. A molecular phylogeny of the genus
Tetragonopterus
placed
M. georgiae
as the sister to all
Tetragonopterus
species (
Melo
et al.
2016
). Thus,
M. georgiae
is herein formally transferred to
Tetragonopterus
.
Material examined:
Types
:
ANSP
94708, 1
paratype,
57.9 mm
SL,
Suriname
/French
Guyana
, upper
Marowijne
,
Tampoc
(into Litany rivier),
J. Géry
,
29 Nov 1957
.
ANSP
112246
, 1
paratype,
33.7 mm
SL,
ANSP
139714, 2
paratypes,
35.9–48.4 mm
SL, French
Guyana
,
Marowijne
basin, middle
Mana River
, between Saut-
Chien
and Saut-Topi-Topi,
J. Géry
,
15 Oct 1957
.
Non-types:
Venezuela
:
ANSP
168083, 39
,
20.5–50.8 mm
SL
,
Bolivar
, Cuyuni basin,
Rio Hacha.
MZUSP
77808, 3
,
34.6–40.9 mm
SL
,
Bolivar
, Rio Nichare.
Guyana
:
ANSP
177000
, not measured
,
Essequibo
basin,
Siparuni river
,
4°44’41”N
59°00’18”W
.
ANSP
190828
, 16
, not measured,
Rupununi region
, upper
Essequibo
,
Yukanopito falls
.
ANSP
190465
, 4
,
35.3–41.5 mm
SL,
Rupununi region
,
Essequibo
basin,
Kuyuwini river
.
ANSP
190525
, 7
,
31.2–56.2 mm
SL,
Rupununi region
,
Essequibo
river,
Kassi-Atae
rapids
.
Suriname
:
ANSP
189638, 3
,
38.4–44.3 mm
SL
;
ANSP
189639, 3
,
38.4–44.3 mm
SL;
Marowijne
basin
,
Sipaliwini
, Anapaike,
Lawa river
.
USNM
229604, 3
,
37–61.9 mm
SL
,
Brokopondo
,
Marowijne
river,
63 km
Z. Van Afobaka.
Brazil
: LBP 21093, 1,
26.4 mm
SL
,
Amapá
,
Oiapoque
,
Rio Oyapock
,
Igarapé Pantanari
,
3°48’47.6”N
51°48’31.6”W
.
MZUSP
16758, 18
, 50.4–68.0 mm SL,
Pará
,
Alto Paru d’Oeste
,
Amazon
basin,
upper Rio Paru
.