A new species of Characidium Reinhardt (Ostariophysi: Characiformes: Crenuchidae) from coastal rivers in the extreme south of Bahia, Brazil
Author
Zanata, Angela M.
Author
Sarmento-Soares, Luisa M.
Author
Martins-Pinheiro, Ronaldo F.
text
Zootaxa
2015
4040
3
371
383
journal article
39437
10.11646/zootaxa.4040.3.8
96814435-9a42-487e-9c56-e05486628602
1175-5326
241465
4B318B78-E866-41A1-9CFC-2515906231BF
Characidium helmeri
,
new species
(
Fig. 1–4
)
Characidium
sp. 2—
Sarmento-Soares
et al
., 2009
: 146
(species list).
Holotype
.
MNRJ
42610,
40.4 mm
SL
,
Brazil
, Bahia, Prado, rio Ribeirão, on road between Cumuruxatiba and Corumbau, tributary of rio Cahy,
17º00’45”S
39º12’07”W
,
17 m
above sea level, L.M. Sarmento-Soares, R.F. Martins-Pinheiro, A.T. Aranda & C.C. Chamon,
24 Oct 2004
.
Paratype
s. All from
Brazil
, Bahia. Prado:
MNRJ
29038, 14,
21.5–35.5 mm
SL
,
MBML
3834, 5,
19.5–26.8 mm
SL
,
MBML
7365, 1 CS,
26.9 mm
SL
, collected with
holotype
.
MZUSP
27003, 1,
32.2 mm
SL
, Cumuruxatiba, rio do Peixe Grande,
17°05’25” S
39°12’54”W
,
17 m
above sea level, R.M.C. Castro,
20 Feb 1979
.
MZUSP
74029, 4,
23.4–28.5 mm
SL
, rio Imbassuaba at Fazenda Embaçoaba,
17°04’53” S
,
39°15’56”W
,
33 m
above sea level, Expedição
MZUSP
/
USNM
,
20 Mar 1985
.
MZUSP
112666
, 24, 1 mol,
16.7–30.3 mm
SL
, rio Ribeirão, tributary of rio Cahy Braço Norte, on road between Barra do Cahy and Ponta do Corumbau,
17º00'45"S
,
39º12'05"W
,
27m
above sea level,
O
.T. Oyakawa, A.M. Zanata, P. Camelier & T.F. Teixeira,
9 Aug 2012
.
MZUSP
112653
, 21, 1 mol, rio Cahy Braço Norte, on road between Barra do Cahy and Ponta do Corumbau,
16º59’10”S
,
39º12’53”W
,
8 m
above sea level,
O
.T. Oyakawa, A.M. Zanata, P. Camelier & T.F. Teixeira,
9 Aug 2012
. Canavieiras:
MZUSP
93899, 1,
32.4 mm
SL
, affluent of rio Salsa, tributary of rio Pardo on road between Ouricana and Pimenteira,
15°43’53”S
,
39°07’44”W
,
19 m
above sea level, N.A. Menezes,
O
.T. Oyakawa, L.M. Sousa & J.C. Nolasco, 0
3 Apr 2006
.
MZUSP
112433
, 1,
32.2 mm
SL
, affuent of rio Salsa, tributary of rio Pardo, on road between Ouricana and Pimenteira,
15°43’55”S
,
39°07’45”W
,
24 m
above sea level,
O
.T. Oyakawa, A.M. Zanata, P. Camelier & T.F. Teixeira,
11 Aug 2012
. Porto Seguro:
MBML
531, 18, 1 CS,
17.2–36.3 mm
SL
, and
MBML
7363, 1 CS,
28.4 mm
SL
, rio Trancoso,
16º35’15”S
,
39º05’41”W
,
9 m
above sea level, R.L. Teixeira & G.I. Almeida, 0
7 Apr 2001
.
MBML
6633, 1,
29.1 mm
SL
, tributary of rio da Barra near boundaries of
RPPN
II Fazenda Sol Poente Trancoso,
16°31’49”S
,
39°08’56”W
,
30 m
above sea level, J.L. Helmer,
14 Nov 2012
.
MBML
6645, 2,
21.9–35.4 mm
SL
, tributary of Córrego Manoelzinho, affluent of rio do Norte, rio da Barra microbasin in
RPPN
II Fazenda Sol Poente in Trancoso village,
16°31’20”S
,
39°08’12”W
,
31 m
above sea level, J.L. Helmer,
17 Nov 2012
.
MBML
6652, 8,
29.6–33.4 mm
SL
, rio do Norte, tributary of rio da Barra, near boundary of
RPPN
V Fazenda Nova Esperança I in Trancoso,
16°32’39”S
,
39°06’50”W
,
9 m
above sea level, J.L. Helmer,
20 Jul 2012
.
MBML
6668, 4,
35.4–39.8 mm
SL
, Córrego Manoelzinho, tributary of rio do Norte, affluent of rio da Barra
RPPN
II Fazenda Sol Poente in Trancoso village,
16°31’21”S
,
39°08’29”W
,
56 m
above sea level, J.L. Helmer,
16 Nov 2012
.
MBML
6673, 1,
27.3 mm
SL
, rio do Norte, tributary of rio da Barra, near boundary of
RPPN
V Fazenda Nova Esperança I in Trancoso,
16°32’39”S
,
39°06’50”W
,
9 m
above sea level, J.L. Helmer,
16 Nov 2012
.
MBML
6680, 10,
18.2–28.6 mm
SL
, Rio do Norte, tributary of rio da Barra in
RPPN
rio do
Brasil
in Trancoso,
16°30’40”S
,
39°08’33”W
,
35 m
above sea level, J.L. Helmer,
23 Jul 2012
.
MBML
6688, 9,
26.5–27.2 mm
SL
, Rio da Barra near boundary of
RPPN
II Fazenda Sol Poente in Trancoso village,
16°32’18”S
, 39°08’34’W,
20 m
above sea level, J.L. Helmer,
19 Jul 2012
.
MBML
6700, 10,
24.3–32.1 mm
SL
, and
MBML
7368, 1 CS,
26.8 mm
SL
, Rio do Norte, tributary of rio da Barra in
RPPN
III Fazenda Sol Nascente, in Trancoso village,
16°31’44”S
,
39°07’18”W
,
24 m
above sea level, J.L.Helmer,
20 Jul 2012
.
MBML
6708, 5,
24.5–37.3 mm
SL
, Rio da Barra, near boundary of
RPPN
II Fazenda Sol Poente and Parque Nacional do Pau
Brasil
near Trancoso,
16°31’45”S
, 39°09’02’W,
32 m
above sea level, J.L.Helmer,
20 Jul 2012
.
MBML
6710, 13, 22,2–
31.5 mm
SL
, Rio da Barra after
RPPN
V Fazenda Nova Esperança I, in Trancoso village,
16°32’44”S
,
39°06’59”W
,
9 m
above sea level, J.L. Helmer,
20 Jul 2012
.
MBML
6720, 6,
19.9–30.5 mm
SL
, córrego Manuelzinho, tributary of rio do Norte, tributary of rio da Barra in the
RPPN
II F Sol Poente in Trancoso,
16°31’21”S
39°08’29”W
,
55 m
above sea level, J.L. Helmer,
21 Jul 2012
.
MBML
6725, 2,
23.8–40.7 mm
SL
, Córrego Manoelzinho, tributary of rio do Norte, tributary of rio da Barra,
RPPN
II Fazenda Sol Poente in Trancoso,
16°31’21”S
, 39°08’29’W,
55 m
above sea level, J.L. Helmer,
24 Jul 2012
.
MBML
6755, 2,
29.9–36.6 mm
SL
, Rio da Barra near boundary of
RPPN
II Fazenda Sol Poente in Trancoso,
16°32’18”S
,
39°08’34”W
,
20 m
above sea level, J.L. Helmer,
14 Nov 2012
.
MBML
6757, 2,
26.6–31.6 mm
SL
, Rio do Norte, tributary of rio da Barra in
RPPN
rio do
Brasil
in Trancoso,
16°30’40”S
,
39°08’33”W
,
35 m
above sea level, J.L. Helmer,
16 Nov 2012
.
MBML
3963, 4,
29.7–35.6 mm
SL
, rio das Águas, tributary of rio Trancoso,
16º33’13”S
,
39º10’03”W
,
42 m
above sea level, J.L. Helmer,
9 Dec 2010
;
MBML
3969, 1,
21.5 mm
SL
, same data,
8 Jun 2010
.
FIGURE 1.
Characidium helmeri
, (a) holotype, MNRJ 42610, 40.4 mm SL, rio Ribeirão, tributary of rio Cahy, Bahia, Brazil; (b) paratype, MBML 531, 36.2 mm SL, rio Trancoso, Bahia, Brazil; (c) paratype, MZUSP 112653, 30.6 mm SL, rio Cahy Braço Norte, Bahia, Brazil; (d) paratype, MNRJ 29038, 23.2 mm SL, same data as holotype.
FIGURE 2
. Paratype of
Characidium helmeri
, MZUSP 112666, 30.3 mm SL, stream on road between Barra do Cahy and Ponta do Corumbau, Bahia, Brazil; photographed live.
Diagnosis.
Characidium helmeri
can be distinguished from congeners by having dark, vertically elongated, irregular, narrow spots or dashes, usually more evident over the midlateral stripe and/or ventral half of body, formed by high concentration of melanophores on the posterior half of scales, occurring in a somewhat curved or zigzag-shape. Also differs from congeners by having extremely reduced or complete absence of supraorbital. The new species further differs by having lateral line reduced (
vs
. complete, except in
C. bahiense
Almeida
,
C. interruptum
Pellegrin
,
C
.
laterale
(Boulenger)
,
C. mirim
Netto-Ferreira, Birindelli & Buckup
,
C
.
nupelia
Graça, Pavanelli & Buckup
,
C
.
rachovii
Regan
,
C. stigmosum
Melo & Buckup
, and
C. xavante
Graça, Pavanelli & Buckup
); adipose fin absent (
vs
. present, except in
C. mirim
,
C. nupelia
,
C. stigmosum
, and
C. xavante
); and isthmus naked on its anteriormost portion (
vs
. isthmus completely covered by scales in most congeners, except in
C. alipioi
Travassos
,
C. boavistae
Steindachner
,
C. crandellii
Steindachner
,
C. declivirostre
Steindachner
,
C. fasciatum
Reinhardt
,
C. gomesi
Travassos
,
C. grajahuensis
Travassos
,
C
.
japuhybense
Travassos
,
C. lauroi
Travassos
,
C. macrolepidotum
(Peters)
,
C. oiticicai
Travassos
,
C. schubarti
Travassos
,
C. timbuiense
Travassos
, and
C. vidali
Travassos
).
Characidium helmeri
differs from
C. bahiense
,
C. interruptum
,
C
.
laterale
,
C. mirim
,
C
.
nupelia
,
C
.
rachovii
and
C. xavante
by having higher number of pored lateral line scales (13–22
vs
. 5–11) and two series of dentary teeth (vs. one). The new species further differs from
C. nupelia
and
C. xavante
by the absence of a dark humeral blotch (vs. present) smaller number of dark vertical bars on the body, 7–12 when present (vs. 12–18).
Characidium helmeri
can be differentiated from
C
.
vestigipinne
, a species with adipose fin absent or reduced, by having two dentary rows of teeth, the outer with tricuspid teeth (vs. one row of conical teeth); 4 scales above lateral line and 4 below (vs. 5 above; and 5 or 6 below); and absence of roundish black marks on pelvic, dorsal, and anal fins (vs. presence). It can be further distinguished from
C
.
stigmosum
by presence of a black basicaudal dot (vs. absence), and by having pelvic, pectoral, anal, and caudal fins not dark pigmented in males (vs. pigmented).
TABLE 1.
Morphometric data of holotype and paratypes of
Characidium helmeri
(number of specimens measured = 44). The range includes the holotype. SD = standard deviation.
Holotype |
Range |
Mean |
SD |
Total length (mm) |
51.6 |
26.7–51.6 |
– |
– |
Standard length (mm) |
40.4 |
20.1–40.4 |
– |
– |
Percents of standard length |
Depth at dorsal-fin origin |
30.9 |
23.8–30.9 |
26.6 |
1.5 |
Depth at anal-fin origin |
22.3 |
16.3–22.3 |
18.9 |
1.2 |
Caudal-peduncle depth |
13.9 |
11.0–14.5 |
12.8 |
0.8 |
Caudal-peduncle length |
18.8 |
15.9–21.6 |
19.0 |
1.3 |
Snout to dorsal-fin origin |
49.3 |
46.7–52.2 |
49.0 |
1.4 |
Snout to pectoral-fin origin |
23.3 |
22.6–29.4 |
26.3 |
1.6 |
Snout to pelvic-fin origin |
54.0 |
51.2–56.7 |
53.9 |
1.3 |
Snout to anal-fin origin |
77.2 |
72.7–79.9 |
76.7 |
1.5 |
Anal-apex distance |
98.5 |
94.2–100.7 |
98.0 |
1.8 |
Body width |
16.8 |
12.4–16.8 |
14.2 |
1.1 |
Head length |
23.5 |
22.3–28.9 |
25.9 |
1.4 |
Percents of head length |
Horizontal eye diameter |
26.3 |
26.3–34.4 |
31.3 |
1.4 |
Snout length |
20.0 |
19.0–25.4 |
21.3 |
1.6 |
Snout to maxillary tip |
26.3 |
22.8–29.2 |
25.9 |
1.5 |
Anterior naris to orbit |
9.5 |
6.3–11.6 |
9.3 |
1.2 |
Posterior naris to orbit |
4.2 |
2.8–5.1 |
3.9 |
0.7 |
Cheek depth |
9.5 |
6.2–11.3 |
8.3 |
1.2 |
Least interorbital width |
17.9 |
13.1–17.9 |
15.3 |
1.3 |
Description.
Morphometric data of
holotype
and selected
paratypes
presented in
Table 1
. Body elongate and moderately compressed. Greatest body depth at vertical through dorsal-fin origin. Dorsal profile convex from upper lip to end of occipital process, slightly convex or straight from this point to origin of dorsal-fin base, convex along dorsal-fin base, almost straight between end of dorsal-fin base to origin of anteriormost dorsal procurrent caudal-fin ray. Ventral profile of head straight, except for slightly convex portion close to dentary symphysis, slightly convex from isthmus to pelvic-fin origin, straight from latter point to anal-fin origin, straight from this point to origin of anteriormost ventral procurrent caudal-fin ray. Snout triangular in lateral view, rounded dorsally. Mouth subterminal, aligned or slightly lower than ventral edge of the orbit. Distal tip of maxilla barely reaching vertical through anterior margin of orbit. Orbit approximately round, larger than snout length. Cheek thin, its depth approximately one third to one sixth of orbit diameter. Nares separated; anterior naris with raised margins, mainly on its posterior border; posterior naris considerably closer to orbit than to anterior naris and with skin flap on its anterior border. Supraorbital absent or extremely reduced and present solely in one side of head (
Fig. 3
). Nasal bones restricted to the ossified canal, without lateral lamella. Parietal fontanel limited anteriorly by frontals. Parietal branch of supraorbital canal absent.
FIGURE 3.
Head dorsum of
Characidium helmeri
, MBML 531, 30.1 mm SL, rio Trancoso, Bahia, Brazil. Arrow indicates vestigial supraorbital.
Dentary teeth in two rows; outer series with 6(6), 7(23), 8*(16) or 9(4) teeth, anterior tricuspid, 3 or 4 posterior unicuspid; teeth decreasing in size from symphysis; inner series with 9(2) or 12(1) several minute conical teeth inserted on edge of replacement tooth trench. Premaxilla with single series of 5(3), 6*(29), or 7 (14) conical teeth, decreasing in size from symphysis. Maxillary edentulous. Ectopterygoid with a single series of 8(1) or 9(1) conical teeth. Mesopterygoid teeth absent.
Scales cycloid;
circulii
absent and around 10
radii
present on exposed portion of scales. Lateral line reduced; perforated scales 13*(7), 14(8), 15(6), 16(3), 17(7), 18(7), 19(2), 20(1), 22(1); total scales along longitudinal line 30(2), 31(12), 32*(22) or 33(5); horizontal scale rows above lateral line 4*(43); horizontal scale rows below lateral line 4*(43). Scales along middorsal line between supraoccipital and origin of dorsal fin around nine or ten, but usually irregularly arranged. Scale rows around caudal peduncle 13 (1) or 14*(40). Isthmus with anteriormost small portion without scales. Pseudotympanum represented by muscular hiatus at vertical through anterior portion of swimbladder and situated over rib of fifth vertebra (
Fig. 4
).
FIGURE 4.
Pseudotympanum of
Characidium helmeri
, MZUSP 112666, 24.9 mm SL, rio Ribeirão, tributary of rio Cahy Braço Norte, Bahia, Brazil.
Dorsal-fin rays ii,9(3), ii,10(12), iii,9*(25) or iii,10(2); distal margin of dorsal fin rounded. Adipose fin absent. Pectoral-fin rays 8–12 total rays, number of unbranched rays highly variable; unbranched anterior rays ii(2), iii(7), iii*(8), iv(28), ix(1) and posteriormost rays varying from by 1–4 unbranched; one specimen with all rays unbranched; number of branched rays ontogenetically variable, increasing in number with size; first and second branched pectoral-fin rays usually longest; posterior tip of pectoral fin extending beyond pelvic-fin insertion. Pelvic-fin rays highly variable, i,4,iii(1), i,4,iv (1), i,5,i (1), i,5,ii(6), i,5,iii(6), i,6,i(10), i,6,ii(7), ii,6,ii(1), i,7(1), i,7,i*(7), or i,8,i(1); second to fourth branched pelvic-fin rays longest; posterior tip of pelvic fin extending beyond anal-fin origin and usually reaching base of second branched anal-fin ray. Anal-fin rays ii,5(1) or ii,6*(42); iii,6(1); posterior margin of anal fin pointed posteriorly, with second branched usually longest; fin elements (i.e., adnate rays) on last pterygiophore 2*(43). Caudal-fin rays i,8,8,i(1), i,9,8,i(2). Dorsal procurrent caudal-fin rays 7(3); ventral procurrent caudal-fin rays 6(2) or 7(1).
Total number of vertebrae 33(1), 34(1) or 35(1); precaudal vertebrae 18(1) or 19(2); caudal vertebrae 15(2) or 16(1). Supraneural bones 4(1), 5(1) or 6(1). Epural bones 3(3). Uroneural bone 1(3). Branchiostegal rays 5(3); 4 connected to anterior ceratohyal, 1 connected to the posterior ceratohyal.
Color in alcohol.
Ground color of head and body pale yellow (
Fig. 1
). Dark stripe extending from snout to posterior margin of opercle. Dorsum of head with a large brown blotch posteriorly, occupying area from vertical through posterior margin of orbit to posterior margin of the supraoccipital bone. Ventral half of head clear, with sparse small melanophores. Dark midlateral stripe usually extending from rear of opercle to end of caudal peduncle; in some specimens stripe faded or absent. Dark humeral blotch absent. Basicaudal black spot well defined. Presence, form, and arrangement of blotches or bars on laterals of body variable. Most specimens with dorsal half of body with 7 to 10 usually inconspicuous dark primary vertical bars, broader dorsally (2 or 3 scales wide); dark and conspicuous narrow dark bars or traces vertically elongate, associated or not to the primary bars, usually more defined over longitudinal band and extending irregularly ventrally; bars on ventral half of body, when present, usually formed by high concentration of dark pigment on posterior half of scales, resulting in curved or somewhat zigzag-shaped spots or dashes, usually not reaching the midventral line of body; posterior half of body usually with vertical bars similarly shaped on dorsal and ventral half, continuous throughout midventral line. In some middle-sized or larger specimens (28.0–36.0 mm SL), spots on dorsolateral area isolated from those distributed over midlateral band and from those more ventrally positioned (when present), resulting in two or three series of spots somewhat horizontally arranged on lateral of body. Smaller specimens, up to 25.0 mm SL, usually with 10–12 continuous narrow vertical bars crossing the sides of the body; bars reaching its contralaterals ventrally on portion posterior to the pelvic fins. Dorsal, anal and caudal fins with melanophores distributed over rays; interradial membranes mostly transparent, except for a black bar near base of dorsal and anal fins. Pectoral and pelvic fins usually without pigmentation but some specimens with melanophores on fin rays.
Color in life
. Ground color of dorsal half of yellowish and ventral half whitish (
Fig. 2
). Pattern of dark spots and bars similar to specimens in alcohol; dark longitudinal stripe and spots on ventral half of body usually more evident than pigmentation on dorsal half. Fins yellowish.
Etymology.
The specific name,
helmeri
, is a genitive noun in honor of Dr. José Luis Helmer, who collected part of the material of the species, and in recognition of his pioneer studies on the natural history of the freshwater fishes in Espírito Santo and Southern Bahia, since 1976.
Sexual dimorphism.
No hooks on fins or other sexually dimorphic features were observed externally on specimens examined.
Distribution.
Characidium helmeri
is known from various small coastal rivers in Southern Bahia (
Fig. 5
), in the vicinity of Canavieiras, Porto Seguro, and Prado.
FIGURE 5.
Map of small coastal river drainages between Cumuruxatiba and Canavieiras, southern Bahia, northeastern Brazil, showing distribution of the new species (blue star represents type locality).
Habitat and ecological notes.
Characidium helmeri
is apparently restricted to slow flowing river stretches, situated
8–91m
above sea level, a few centimeters to
1.5 m
deep, with transparent or dark water running in substrate composed by pebbles, gravel, or organic debris (
Fig. 6
). The riparian vegetation is composed by secondary forest, with plenty floating meadows and submersed vegetation in portions of the river bank. The new species was collected syntopically with
Aspidoras virgulatus
Nijssen & Isbrucker,
Astyana
x s
p., Geophagus brasiliensis
(Quoy & Gaimard),
Hoplerythrinus uniaeniatus
(Agassiz)
,
Hoplias malabaricus
(Bloch)
,
Mimagoniates microlepis
Steindachner
,
M. sylvicola
Menezes & Weitzman
,
Scleromystax prionotos
(Nijssen & Isbrucker)
,
Otothyris travassosi
Britski & Schaefer
,
Phalloceros ocellatu
s Lucinda, including the endangered species
Acentronichthys lepto
s Eigenmann & Eigenmann and
Rachoviscus graciliceps
Weitzman & Cruz. The
stomach contents of four specimens of
C. helmeri
analyzed (
26.8–35.9 mm
SL) contained small aquatic insect larvae, mainly
Chironomidae
, nymphs, fragments of insects, vegetable debris and organic matter partially digested.