Description of a new species of annual fish, Maratecoara gesmonei (Cyprinodontiformes: Rivulidae) from the rio Xingu system, Amazon basin, Brazil.

Abstract

Maratecoara gesmonei n. sp., found on a temporary pool at a fluvial island in the middle rio Xingu, Pará State, Brazil, is described herein. This is the first occurrence of this genus in the Rio Xingu drainage, Amazon basin. The new species differs from all congeners by its unique color pattern which lacks horizontal rows of small dark orange spots on the antero-dorsal portion of the flanks (vs. 2-3 on M. lacortei, 3 on M. formosa and M. splendida), or orange oblique bars on anteroventral portion of trunk (vs. 4-5 orange oblique bars on anteroventral portion of trunk in M. formosa, 3-4 in M. splendida or a broad blotch in M. lacortei). In addition, the new species can be diagnosed from congeners by its lower body depth (23.7-25.9% SL vs. 30.4-40.0% SL), lower caudal peduncle depth (13.0-15.5% SL vs. 17.1-21.6% SL), and lower number of vertebrae, 25-26 (vs. 27-28 in M. lacortei, 26-27 in M. formosa, and 27 in M. splendida).

Full text

Abstract
Maratecoara gesmonei n. sp., found on a temporary pool
at a fluvial island in the middle rio Xingu, Pará State,
Brazil, is described herein. This is the first occurrence of
this genus in the Rio Xingu drainage, Amazon basin. The
new species differs from all congeners by its unique color
pattern which lacks horizontal rows of small dark orange
spots on the antero-dorsal portion of the flanks (vs. 2-3 on
M. lacortei, 3 on M. formosa and M. splendida), or orange
oblique bars on anteroventral portion of trunk (vs. 4-5 or-
ange oblique bars on anteroventral portion of trunk in M.
formosa, 3-4 in M. splendida or a broad blotch in M. la-
cortei). In addition, the new species can be diagnosed from
congeners by its lower body depth (23.7-25.9% SL vs.
30.4-40.0% SL), lower caudal peduncle depth (13.0-
15.5% SL vs. 17.1-21.6% SL), and lower number of ver-
tebrae, 25-26 (vs. 27-28 in M. lacortei, 26-27 in M. for-
mosa, and 27 in M. splendida).
Resumo
Maratecoara gesmonei n. sp., encontrada em uma poça tem-
porária em uma ilha fluvial no médio rio Xingu, estado do
Pará, Brasil, é aqui descrita. Esta é a primeira ocorrência do
gênero na drenagem do Rio Xingu, bacia Amazônica. A no-
va espécie difere de todas as congêneres pelo padrão único de
cor com ausência de linhas horizontais e pequenas manchas
laranjas escuras na porção antero-dorsal dos flancos (vs. 2-3
na M. lacortei, 3 em M. formosa e M. splendida), ou barras
oblíquas laranjas (vs. 4-5 barras oblíquas laranja em M. for-
mosa, 3-4 em M. splendida ou uma grande mancha em M.
lacortei). Adicionalmente, a nova espécie pode ser diagnosti-
cada de suas congêneres pela menor altura do corpo (23.7-
25.9% SL vs. 30.4-40.0% SL), menor altura pedúnculo
caudal (13.0-15.5% SL vs. 17.1-21.6% SL) e pelo menor
número de vértebras, 25-26 (vs. 27-28 em M. lacortei, 26-
27 em M. formosa e 27 em M. splendida).
Zusammenfassung
Beschrieben wird hier Maratecoara gesmonei n. sp, deren
Vertreter in einem zeitlich begrenzten Tümpel auf einer
Flussinsel im mittleren Rio Xingu im Bundesstaat Pará in
Brasilien entdeckt wurden. Es handelt sich um den ersten
Nachweis dieser Gattung im Einzugsgebiet des Xingu im
Amazonasbecken, Brasilien. Die neue Art unterscheidet sich
von allen anderen Angehörigen der Gattung durch das un-
verkennbare Farbmuster: die waagerechten Reihen kleiner,
dunkel orangefarbener Flecken im vorderen Rückenbereich
der Flanken fehlen hier (im Gegensatz dazu sind bei M. la-
cortei 2-3 Reihen, bei M. formosa und M. splendida 3 Fleck-
enreihen vorhanden); auch fehlen hier die orangefarbigen
schrägen Streifen im vorderen bauchseitigen Teil des
Rumpfes (bei M. formosa sind 4-5 schräge orangefarbene
Streifen vorhanden, bei M. splendida 3-4, bei M. lacortei ein
breiter Fleck). Weitere Unterscheidungsmerkmale von den
anderen Art der Gattung sind: eine geringere Körpertiefe
(23,7-25,9 % der Standardlänge SL im Gegensatz zu 30,4-
40,0% der SL bei den anderen Arten), eine geringere
Schwanzstieltiefe (13,0-15,5% der SL vs. 17,1-21,6% der
SL) sowie eine kleinere Wirbelzahl (25-26 im Vergleich zu
27-28 bei M. lacortei, 26-27 bei M. formosa und 27 bei M.
splendida).
Résumé
Maratecoara gesmonei n. sp., trouvé dans une mare tem-
poraire sur une île fluviale du moyen Rio Xingu, état de
Pará, Brésil, est décrit ci-après. C’est la première occur-
rence de ce genre dans le système du Rio Xingu, bassin de
l’Amazone. La nouvelle espèce se distingue de tous ses con-
génères par un patron de coloration unique qui ne com-
prend pas de rangées horizontales de petites taches orange
foncé sur la partie antérodorsale des flancs (contre 2-3
pour M. lacortei, 3 pour M. formosa et M. splendida) ou des
barres obliques orange sur la partie antéroventrale du tronc
aqua vol. 20 no. 2 - 15 April 2014
87
aqua, International Journal of Ichthyology
Description of a new species of annual fish, Maratecoara gesmonei
(Cyprinodontiformes: Rivulidae) from the rio Xingu system,
Amazon basin, Brazil
Dalton Tavares Bressane Nielsen1, Mayler Martins2and Ricardo Britzke3
1) Laboratório de Zoologia, Departamento de Biologia, Universidade de Taubaté,
Pça Marcelino Monteiro 63, CEP: 12030-010, Taubaté, SP, Brazil. E-mail: dnielsen@uol.com.br
2) Instituto Federal Minas Gerais- Campus Bambuí- Fazenda Varginha-Estrada Bambuí-Medeiros Km 5,
CEP: 38900-000, MG, Brazil. E-mail: maylermarins@yahoo.com.br
3) Universidade Estadual Paulista, Instituto de Biociências, Departamento de Morfologia, Rubião Jr. s/n.
CEP 18618-970. Botucatu, SP, Brazil. E-mail: britzke_r@yahoo.com.br
Received: 13 February 2014 – Accepted: 03 April 2014

(contre 4-5 barres obliques orange sur la partie antéroven-
trale du tronc pour M. formosa, 3-4 pour M. splendida ou
une large tache pour M. lacortei). En outre, la nouvelle
espè ce peut être séparée de ses congénères par sa plus faible
hauteur du corps (23,7-25,9 % de LS vs. 30,4-40,0 de LS),
une plus faible hauteur du pédoncule caudal (13,0-15,5 %
de LS vs. 17,1-21,6 % de LS) et un nombre inférieur de
vertèbres, 25-26 (vs. 27-28 pour M. lacortei 26-27 pour M.
formosa et 27 pour M. splendida).
Sommario
Maratecoara gesmonei n. sp., trovata in una pozza tempo-
ranea su un'isola fluviale del medio corso del Rio Xingu,
Stato di Parà, Brasile, viene qui descritta. Questa è la prima
segnalazione di questo genere nel sistema del Rio Xingu,
bacino idrografico amazzonico. La nuova specie si differen-
zia da tutte le congeneri per la particolare colorazione
caratterizzata dall’assenza di righe orizzontali di piccole
macchie di colore arancione scuro sulla porzione antero-
dorsale dei fianchi (vs. 2-3 a M. lacortei, 3 su M. formosa e
M. splendida) o barre oblique arancione sulla parte an-
teroventrale del tronco (vs. 4-5 barre oblique arancione su
parte anteroventrale del tronco in M. formosa e 3-4 in M.
splendida o un’estesa macchia in M. lacortei). Inoltre, la
nuove specie può essere diagnosticata dalle congeneri per
una minore altezza del corpo (23.7-25.9% SL vs. 30.4-
40.0% SL), una minore altezza del peduncolo caudale
(13.0-15.5% SL vs. il 17.1-21.6% SL) e un minor numero
di vertebre, 25-26 (vs. 27-28 in M. lacortei, 26-27 in M.
formosa e 27 in M. splendida).
INTRODUCTION
In the middle of the 1980’s, annual fish enthusiasts
collected three undescribed species of annual fish
from the family Rivulidae in a temporary pool near
the city of Aruanã, located on the right bank of the
rio Araguaia, Goiás state, Brazil. These three new
species were then temporarily identified by the codes
GO-1, GO-2, and GO-3. All three species were very
beautiful and distinct from what was then known to
ichthyologists and aquarists at the time. One of
them, GO-3, called a great deal of attention because
it possessed a metallic blue coloration and long ex-
tensions on the dorsal and anal fins, recalling anoth-
er species of annual fish, Terranatos dolichopterus
Weitzman & Wourms, 1967, from the río Orinoco
basin in Venezuela. Not until 1991 were these three
species finally described as belonging to the genus
Cynolebias Steindachner, 1876. The species that was
initially designated with the code GO-3 was de-
scribed as Cynolebias lacortei (Lazara, 1991).
Costa (1995a) erected a new genus, Maratecoara,
and the species Cynolebias lacortei became the type
species of this new genus. In the same work, a sec-
ond species of Maratecoara was described, Marate-
coara formosa Costa & Brazil, 1995. It originates
from the city of Brejinho do Nazaré, Tocantins state,
and was found in an annual pool in the left bank of
the rio Tocantins. More recently, Costa (2007), de-
scribed one additional new species, Maratecoara
splendida Costa, 2007, originating from an annual
pool located close to the rio Canabrava, a tributary
of the left bank of the rio Tocantins.
The genus Maratecoara belongs to the subfamily
Rivulinae Myers 1925, tribe Rachoviini Costa,
1990 and the subtribe Plesiolebiina Costa, 1990.
Within the subtribe Plesiolebiina, are also included
the genera Plesiolebias Costa 1989, Pituna Costa
1989, Papiliolebias Costa 1998, and Stenolebias
Costa 1995a. So far, the genus Maratecoara species
is known exclusively from the rio Tocantins/
Araguaia basin in central Brazil. The new species
described herein is the first found outside this sys-
tem, at the middle rio Xingu basin, a the right
bank tributary of the Amazon River. It is also the
first species described from the Amazon forest do-
main - the other species are found in the savannah-
like Cerrado domain.
MATERIAL AND METHODS
Measurements were taken point-to-point under
the stereomicroscope with the digital caliper to the
nearest 0.01mm, on the left side of the specimen
whenever possible, following Costa (1995b, 2007).
Measurements are expressed as percentages of stan-
dard length (SL), except subunits of the head,
which are recorded as percentages of head length
(HL).
In the description, counts of vertebrae and pleural
ribs were taken from cleared and stained (c&s)
specimens, one male and one female paratypes,
prepared according to Taylor & Van Dyke (1985).
Terminology for frontal squamation follows
Hoedeman (1958) and Costa (2006). For vertebral
counts the caudal compounded centrum was
counted as a single element. Osteological features
included in the description are those considered
phylogenetically informative by recent studies on
Plesiolebiasiina (Costa 2007). Institutional abbre-
viations are LBP (Laboratório de Biologia e
Genética de Peixes, Universidade Estadual Paulista,
Botucatu, Brazil), UNITAU (Universidade of
Taubaté, Taubaté, Brazil), and ZUEC (Museu de
Zoologia da Universidade Estadual de Campinas,
Campinas, Brazil). Comparisons with congeners
were based primarily on the literature (Costa,
2007).
aqua vol. 20 no. 2 - 15 April 2014 88
Description of a new species of annual fish, Maratecoara gesmonei (Cyprinodontiformes: Rivulidae) from the rio Xingu system, Amazon basin, Brazil

Maratecoara gesmonei, n. sp.
(Figs 1-2; Table I)
Holotype: ZUEC 7851, male 23.4 mm SL: Brazil,
Pará state, São Félix do Xingu, temporary pool at
island in the middle of the rio Xingu 06°39’33.3’’
S 52°00’21.9’’ W; 17 May 2013, Ricardo Britzke
& Mayler Martins.
Paratypes: LBP 18387, four males, 18.5-20.4 mm
SL, six females, 17.9-24.5 mm SL, collected with
the holotype. ZUEC 7852 (2 c&s), one male 19.6
mm SL and one female 18.8 mm SL, collected
with the holotype.
Diagnosis: Males of Maratecoara gesmonei differs
from the remaining congeners by a lower body
depth (23.7-25.9% SL vs. 30.4-40.0% SL); lower
caudal peduncle depth (13.0-15.5% SL vs. 17.1-
21.6% SL); lower length of dorsal-fin base (13.5-
14.5% SL vs. 14.9-19.6% SL); lower length of
anal-fin base (19.7-21.5% SL vs.20.3-27.2% SL);
lower caudal-fin length (34.1-41.4% SL vs. 49.2-
62.5% SL); lower pelvic-fin length (12.2-14.8%
aqua vol. 20 no. 2 - 15 April 2014
89
Dalton Tavares Bressane Nielsen, Mayler Martins and Ricardo Britzke
Fig. 1. Maratecoara gesmonei, ZUEC 7851, holotype, male, 23.4 mm SL. Photo by M. Martins.
Fig. 2. Maratecoara gesmonei, LBP 18387, paratype, female, 24.5 mm SL. Photo by M. Martins.

SL vs.15.0-20.0% SL); lower head depth (62.5-
64.6% HL vs.92.2-112.4% HL); lower head
width (33.8-35.7% HL vs.54.9-65.8% HL); pec-
toral-fin posterior margin reaching vertical be-
tween base of the 1st and 2nd anal-fin rays (vs.
5thand 7th in M. lacortei, 4th and 5th in M. formosa,
and 4th and 6th in M. splendida); contact organs
absent (vs. 3-5 on posterior margin of each scale on
ventral portion of flanks in males in M. lacortei, M.
formosa, and M. splendida); anal-fin origin between
pleural ribs of 12th and 13th vertebrae (vs.10th and
11th in M. lacortei and M. formosa, 10th and 12th
in M. splendida); lower number of caudal-fin rays,
24-25 (vs. 27-30 in M. lacortei, 25-26 M. formosa,
and 25-27 M. splendida); lower number of pelvic-
fin rays, 7 (vs. 8 in M. lacortei, M. formosa, and M.
splendida); lower number of transverse series of
scales, 8 (vs.9-10 in M. lacortei, 9 in M. formosa,
and M. splendida); lower number vertebrae, 25-26
(vs. 27-28 in M. lacortei, 26-27 M. formosa, and 27
in M. splendida). Additionally, males of Marate-
coara gesmonei differs from males of the remaining
species of the genus Maratecoara by presenting a
body color pattern without horizontal rows of
small dark orange spots on the antero-dorsal por-
tion of flanks (vs. 2-3 in M. lacortei, 3 in M. for-
mosa and M. splendida), by lacking orange oblique
bars on anteroventral portion of trunk (vs. 4-5 or-
ange oblique bars on anteroventral portion of
trunk in M. formosa, and 3-4 in M. splendida, and
a broad blotch in M. lacortei), and by presenting
overall body coloration with irregular stains of or-
ange and metallic blue (vs.overall body coloration
metallic blue with horizontal orange spots in M. la-
cortei, metallic blue with horizontal and oblique
orange spots in M. formosa and M. splendida).
aqua vol. 20 no. 2 - 15 April 2014 90
Description of a new species of annual fish, Maratecoara gesmonei (Cyprinodontiformes: Rivulidae) from the rio Xingu system, Amazon basin, Brazil
Table I. Morphometric and meristic data for the holotype (H) and paratypes of Maratecoara gesmonei. SD = Standard devi-
ation.
H Paratypes Mean±SD
Male Male n=5 Females n=7
Standard length (mm) 23.4 18.5-20.4 17.9-24.5 19.4±1.53
Percents of SL
Body depth 25.9 23.7-25.9 23.9-25.9 24.9±0.87
Caudal peduncle depth 15.5 13.0-15.5 12.7-12.9 13.8±1.26
Pre-dorsal length 66.8 63.2-67.8 60.1-66.8 65.9±1.82
Pre-pelvic length 51.8 49.5-51.8 52.8-53.2 52.1±1.12
Length of dorsal-fin base 14.5 13.5-14.5 11.3-13.3 13.2±1.17
Length of anal-fin base 19.7 19.7-21.5 15.9-18.1 18.4±2.05
Caudal-fin length 41.4 34.1-41.4 31.9-37.2 36.0±3.17
Pectoral-fin length 23.3 23.3-27.2 19.1-23.8 23.7±2.27
Pelvic-fin length 14.8 12.2-14.8 12.7-14.9 13.5±1.02
Head length 37.3 34.6-37.7 33.6-36.2 35.5±1.47
Percents of HL
Head depth 62.5 62.5-64.6 63.0-64.7 06.7±0.83
Head width 34.7 33.8-35.7 35.3-39.7 63.4±2.37
Lower jaw length 13.8 13.8-15.4 12.8-14.4 14.3±0.67
Eye diameter 31.9 30.8-34.3 30.8-33.3 32.0±1.10
Counts
Dorsal fin 11 11 10
Caudal fin 24 25 24
Anal fin 14 14-15 14
Pelvic fin 7 7 7
Pectoral fin 13 13 13
Meristic
Scales in longitudinal series 25-26 25
Scales in transversal series 8 8
Horizontal scales around caudal peduncle 16 16

Females of Maratecoara gesmonei differ from fe-
males of remaining species of the genus Marate-
coara by presenting a lower body depth (23.9-
25.9% SL vs.28.2-34.3% SL); lower caudal pe-
duncle depth (12.7-12.9% SL vs.15.1-18.4% SL);
lower length of dorsal-fin base (11.3-13.3% SL vs.
13.6-16.5% SL); lower length of anal-fin base
(15.9-18.1% SL vs.19.3-22.2% SL); lower caudal-
aqua vol. 20 no. 2 - 15 April 2014
91
Dalton Tavares Bressane Nielsen, Mayler Martins and Ricardo Britzke
Fig. 3. Geographic distribution of the species of the genus Maratecoara.

fin length (31.9-37.2% SL vs.39.6-43.2% SL);
lower pectoral-fin length (19.1-23.8% SL vs.24.5-
29.7% SL); lower head depth (63.0-64.7% HL vs.
78.1-90.1% HL); lower head width (35.3-39.7%
HL vs.53.3-61.5% HL); and lower eye diameter
(30.8-33.0% HL vs.34.4-37.9% HL).
Description: Morphometric data presented in
Table I. Largest male examined 23.4 mm SL, largest
female examined 24.5 mm SL. Dorsal profile slight-
ly concave between head and base of dorsal-fin,
slightly convex at caudal peduncle. Ventral profile
gently convex from lower jaw to end of anal-fin base
and nearly straight from latter point to caudal pe-
duncle. Body moderately slender, greatest body
depth at level of pelvic-fin base. Jaws short, prog-
nathous, snout slightly pointed. Dorsal fin elongat-
ed in males, pointed, rays 7-8 much more elongated
than remaining rays, filamentous, tips reaching at
least distal margin of caudal fin when adpressed to
the body; anal fin pointed in males, pointed, rays 7-
8 much more elongated than remaining rays, fila-
mentous, tips reaching distal margin of caudal fin
when adpressed to body; dorsal and anal fins just
slightly pointed in females. Caudal-fin lanceolate in
males, middle caudal-fin rays filamentous, caudal-
fin rounded in females. Pectoral-fin elliptical, distal
margin reaching vertical between base of 1st and 2nd
anal-fin rays in males, between urogenital papilla
and anal-fin origin in females. Pelvic-fin elliptical,
without filaments; tip of each pelvic fin reaching be-
tween base of 3rd and 4th anal-fin rays in males,
reaching to between base of 1st and 2nd anal-fin rays
in females. Pelvic-fin bases in close proximity medi-
ally. Dorsal fin origin on vertical between base of 3rd
and 5th anal-fin rays, and between neural spines of
11th and 12th vertebrae in males and 13th and 14tth
in females. Anal fin origin between pleural ribs of
12th and 13th vertebrae. Dorsal-fin rays 10-11; anal-
fin rays 14-15; caudal-fin rays 24-25; pectoral-fin
rays 13; pelvic-fin rays 7.
Scales cycloid: No scales on caudal, dorsal and anal-
fins bases. Frontal squamation F-patterned; E-scales
not overlapping medially; scales arranged in regular
transverse pattern. Longitudinal series of scales 25-
26; transverse series of scales 8; scale rows around
caudal-fin peduncle 16. Contact organs absent.
aqua vol. 20 no. 2 - 15 April 2014 92
Description of a new species of annual fish, Maratecoara gesmonei (Cyprinodontiformes: Rivulidae) from the rio Xingu system, Amazon basin, Brazil
Fig. 4. Type locality of Maratecoara gesmonei, pool at island at the middle of the Rio Xingu, in front of São Félix does Xingu,
Pará, Brazil. Photo by M. Martins.

aqua vol. 20 no. 2 - 15 April 2014
93
Dalton Tavares Bressane Nielsen, Mayler Martins and Ricardo Britzke
Fig. 5. Physical map of eastern South America, showing the Araguaia-Tocantins depression and the Transbrasiliano Linea-
ment.

aqua vol. 20 no. 2 - 15 April 2014 94
Description of a new species of annual fish, Maratecoara gesmonei (Cyprinodontiformes: Rivulidae) from the rio Xingu system, Amazon basin, Brazil
Fig. 6. Geographic distribution of the genera Pituna and Plesiolebias.

Cephalic neuromasts: supraorbital 6+3, parietal 3,
anterior rostral 1, posterior rostral 1, infraorbital 1 +
25, preorbital 4, otic 1, post-otic 2, supratemporal 1,
median opercular 1, ventral opercular 1, preopercu-
lar 14, mandibular 8, lateral mandibular 5.Two neu-
romasts on fin base. Total vertebrae 25-26.
Coloration in life (Figs 1-2). Males: Sides
of body metallic blue and orange with irregular col-
or distribution, without bars or lines, dorsally or-
ange. Abdominal region clear. Sides of head metal-
lic blue and orange. Jaws orange. Iris bright green;
a black bar vertically crossing the eye. Dorsal-fin or-
ange with metallic blue blotches. Anal-fin metallic
blue with slightly orange stains. Caudal-fin orange
with metallic blue spots. Pectoral-fins hyaline.
Pelvic-fins metallic blue with an orange spot.
Females: Overall color light brownish gray, with
longitudinal rows of pale brown dots on the sides
of body. Abdominal region clear. Sides of head and
jaws gray, with a pale greenish yellow hue. Iris yel-
low, with a dark gray vertical bar through center of
eye. Fins hyaline.
Distribution: Currently only known from the
type-locality, a temporary pool at an island from
middle rio Xingu, Amazon basin, Pará state, Brazil
(Fig. 3).
Habitat (Fig. 4): The type-locality lies in a
plateau area of Brazil (198 m a.s.l.), on an island in
the middle of the rio Xingu, in front of the city of
São Félix do Xingu. The island has a total area of
about 465m2and a perimeter of about 3.160 km.It
lies about 330 m from the left bank of the river and
about 540 m from the right bank. The annual pool
is very large with most of its area within a dense
forest. Water temperature, at the depth of 25 cm
was 26.5°C, whereas at the marginal area of the
pool, at the depth of 5 cm, was 27.5°C. The aver-
age depth of the pool was 0.5 m, with the deepest
portions about 1.20 m. Water color was dark and
acidic, with pH 5.5. Other physic-chemical para-
meters were: electric conductibility 8 µS, total
hardness (GH) 0°dGH, carbonate hardness (KH)
0°dGH, dissolved iron (Fe) 0.5 mg/l, dissolved cal-
cium (Ca) 0 mg/l, dissolved copper (Cu) 0 mg/l,
dissolved phosphate (PO4) 0.1 mg/l, and ammoni-
um/ammonia (NH3/NH4) 0 mg/l.
Other annual fish species collected syntopically
were Pituna xinguensis and Plesiolebias altamira.
The pool was beginning to dry up and the collec-
tors also found juveniles of the following characi-
form fish species living syntopically: Moenkhausia
xinguensis, M. ceros, Jupiaba sp., Hyphessobrycon sp.,
Thayeria boehlkei; Serrassalmus sp., and Hoplias
malabaricus. Other aquatic animals recorded at the
site were tadpoles and freshwater crabs. Aquatic
vegetation was not present and the bottom was
composed of clay, leaves, sand and mud. Marate-
coara gesmonei was always found in areas close the
margin of the pool, nearby submerged trunks, at
about 50 cm depth, while Pituna xinguensis was
found in more shallow areas (about 5 cm deep) and
Plesiolebias altamira in deeper areas (about 1 meter
deep).
Etymology: The specific name gesmonei is treated
as a patronym in gratitude and recognition to Ges-
mone Fernandes Godoy, who discovered the
species.
DISCUSSION
The genus Maratecoara is defined by the follow-
ing synapomorphies: long dorsal and anal fins with
tips extending beyond the posterior margin of cau-
dal-fin; caudal-fin lanceolate, tip with two or three
filamentous rays; long opercular membranes with
blue iridescence, extending on to the anterior por-
tion of pectoral-fin; and flanks metallic blue with
orangish golden spots (Costa, 2007).
The discovery of annual pools in São Félix do
Xingu increases the knowledge of distribution of
annual fishes in the rio Xingu basin, which were so
far only known to the neighborhoods of Altamira,
where the Belo Monte dam is currently being
build. The building of this dam will probably de-
stroy the known habitat of the annual fishes that
were so far known from the rio Xingu basin, i.e.,
Spectrolebias reticulatus, Plesiolebias altamira, Pitu-
na xinguensis and Rivulus xinguensis. Fortunately,
Pituna xinguensis and Plesiolebias altamira were
found occurring syntopically with Maratecoara ges-
monei, and consequently will not be extirpated by
the building of the Belo Monte dam. São Felix do
Xingu is about 384 km in a straight line from Al-
tamira, and very likely, more habitats for annual
fishes exist in the intervening area.
The type locality of Maratecoara gesmonei is con-
siderably distant from the other known localities of
Maratecoara species, i.e., 932 km from the type-lo-
cality of M. lacortei, 815 km from the type-locality
of M. splendida and 640 km from the type-locality
of M. formosa (Fig. 3). All Maratecoara species are
only known from their type localities locations,
with the exception for M. lacortei, which is known
from several sites at the rio Araguaia at the city of
Aruanã and its tributary, the rio das Mortes, and
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95
Dalton Tavares Bressane Nielsen, Mayler Martins and Ricardo Britzke
AQUA20(2)-LAYOUT.qxp_AQUA 18/04/14 13:37 Pagina 95

downstream into the Ilha do Bananal. Although
the genus probably has a natural patchy distribu-
tion, this disjunctness may be a sampling artifact,
both due to the relatively little fieldwork directed
to the search of annual fishes, and also due to a
possible great contraction of available habitat for
the species of the genus and for annual fishes as a
whole caused by the massive destruction of the
Cerrado vegetation domain in Central Brazil,
which is being replaced by large monoculture plan-
tations.
The occurrence of the new species Maratecoara
gesmonei in the rio Xingu basin might be associated
to the neotectonic activity across the Transbrasil-
iano Lineament area, a mega linear structure with
about 2700 km, which begins in upper Paraguay
River, crossing the Brazilian Shield to the northeast
coast of Brazil, which also is hypothesized as the
geological drive behind current ranges of other fish
taxa occurring across shield-draining river basins of
Central Brazil (Lima & Ribeiro 2011) (Fig. 5).
These authors reported that the distribution of sev-
eral fish taxa was probably shaped by several head-
waters captures generated by neotectonic activity
between the Pantanal depression and Araguaia-To-
cantins depression, which probably allowed a inter-
change of fish populations among distinct river
basins. Other genera of the subtribe Plesiolebiina,
like Plesiolebias and Pituna, possess a similar distri-
bution along the Transbrasilian Lineament and
they also occur in the middle and lower rio Xingu
region (Fig. 6).
ACKNOWLEDGEMENTS
We are grateful to Flávio C. T. Lima (ZUEC) and
Claudio Oliveira (LBP) for curatorial assistance
and Itamar Alves Martins from Universidade de
Taubaté (UNITAU) for laboratory support; Dr.
Roger David Brousseau who reviewed the English
version and Flávio C. T. Lima (ZUEC) for reading
the manuscript and for offering useful suggestions.
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aqua vol. 20 no. 2 - 15 April 2014 96
Description of a new species of annual fish, Maratecoara gesmonei (Cyprinodontiformes: Rivulidae) from the rio Xingu system, Amazon basin, Brazil