A new species of Moenkhausia Eigenmann (Characiformes: Characidae) from the upper rio Machado at Chapada dos Parecis, rio Madeira basin, Brazil

Abstract

Uma espécie nova de Moenkhausia é descrita do alto rio Machado na Chapada dos Parecis, bacia do rio Madeira, Rondônia, Brasil. Entre as congêneres, a espécie nova é semelhante à Moenkhausia chlorophthalma , M. cotinho , M. lineomaculata , M. plumbea e M. petymbuaba por ter manchas escuras na região anterior das escamas, que estão ausentes nas demais espécies do gênero. A espécie nova difere das espécies mencionadas acima por possuir olhos azuis em vida, 15-18 raios ramificados na nadadeira anal e uma mancha arredondada bem definida no pedúnculo caudal, que não alcança o limite superior e inferior do pedúnculo caudal, e não se estende sobre os raios medianos da nadadeira caudal.

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Neotropical Ichthyology, 14(1): e150041, 2016 Journal homepage: www.scielo.br/ni
DOI: 10.1590/1982-0224-20150041 Published online: 07 April 2016 (ISSN 1982-0224)
37
A new species of Moenkhausia Eigenmann (Characiformes: Characidae)
from the upper rio Machado at Chapada dos Parecis,
rio Madeira basin, Brazil
William M. Ohara and Manoela M. F. Marinho1
A new species of Moenkhausia is described from the upper rio Machado at Chapada dos Parecis, rio Madeira basin, Rondônia
State, Brazil. Among congeners, the new species is similar to Moenkhausia chlorophthalma, M. cotinho, M. lineomaculata,
M. plumbea, and M. petymbuaba by having dark blotches on the anterior portion of the body scales, which are absent in the
remaining species of the genus. The new species differs from aforementioned species by possessing blue eyes in life, 15-18
branched anal-n rays, and a well-dened, round caudal-peduncle spot that does not reach the upper and lower margins of
the caudal peduncle and does not extend to the tip of the middle caudal-n rays.
Uma espécie nova de Moenkhausia é descrita do alto rio Machado na Chapada dos Parecis, bacia do rio Madeira, Rondônia,
Brasil. Entre as congêneres, a espécie nova é semelhante à Moenkhausia chlorophthalma, M. cotinho, M. lineomaculata, M.
plumbea e M. petymbuaba por ter manchas escuras na região anterior das escamas, que estão ausentes nas demais espécies
do gênero. A espécie nova difere das espécies mencionadas acima por possuir olhos azuis em vida, 15-18 raios ramicados
na nadadeira anal e uma mancha arredondada bem denida no pedúnculo caudal, que não alcança o limite superior e inferior
do pedúnculo caudal, e não se estende sobre os raios medianos da nadadeira caudal.
Keywords: Amazon basin, Fish, Moenkhausia cotinho, Ostariophysi, Taxonomy.
Museu de Zoologia da Universidade de São Paulo, Caixa Postal 42494, 04299-970 São Paulo, SP, Brazil.
(WMO) willianmohara@gmail.com (corresponding author), (MMFM) manumfm@yahoo.com.br
Introduction
The species of Moenkhausia Eigenma n n, 1903 are
widely distributed throughout the Neotropical Cis-Andean
river basins, except for those in Patagonia, with greatest
diversity occurring in the basins of the Amazon and
Guianas (Lima et al., 20 03). Moenkhausia is one of the most
species-rich characid genera, currently comprising 80 valid
species (Eschmeyer, 2015). Eigenmann (1903) proposed the
genus based mainly on the combination of the presence of
two rows of premaxillary teeth, ve teeth on the inner row,
completely pored lateral-line scales, a relatively straight
lateral line, and small scales partially covering the caudal-
n lobes.
Lima et al. (2013) recorded twenty species of
Moenkhausia in the rio Madeira basin, two of which were
considered putatively new. During recent eldwork in the
upper rio Machado drainage, which is a major tributary
of the rio Madeira in the state of Rondônia, an additional
undescribed species was discovered and is herein described.
The aim of the present contribution is to describe this new,
beautifully-colored and apparently range-restricted species,
and discuss its taxonomic placement among its congeners.
Material and Methods
Counts follow Fink & Weitzman (1974), except for the
number of horizontal scale rows below lateral line, which is
counted to the pelvic-n insertion (excluding the axillary
scale) rather than to the anal-n origin. Measurements
follow Fink & Weitzman (1974) with the addition of the
distance from pelvic-n origin to anal-n origin. Standard
length (SL) is expressed in millimeters (mm) and all other
measurements are expressed as percentages of SL, except
subunits of the head, which are expressed as percentages
of head length. In the description, counts are followed by
their absolute frequency in parentheses. Asterisks indicate
the counts of the holotype. Scale circuli and radii were
counted from the scale row immediately dorsal to the lateral
line at the vertical through the dorsal-n origin. Counts of
supraneurals, branchiostegal rays, gill-rakers of the rst
branchial arch, tooth cusps, diminutive dentary teeth,
unbranched anal-n rays, procurrent caudal-n rays, and
the position of pterygiophores were taken from cleared and
stained (c&s) specimens prepared according to Taylor &
Van Dyke (1985). Vertebrae of the Weberian apparatus are
counted as four elements and the compound caudal centrum

New Moenkhausia from the rio Madeira basin
Neotropical Ichthyology, 14(1): e150041, 2016
38
(PU1+U1) as a single element. Precaudal vertebral counts
include the Weberian apparatus and the vertebrae lacking
haemal spines. Caudal vertebral counts include all vertebrae
with haemal spines. Catalog numbers are followed by the
total number of specimens and their SL range. The number
of measured and counted specimens (if any) and the number
of cleared and stained specimens (indicated by c&s) is
given in parentheses, followed by their respective SL range.
Institutional abbreviations follow Ferraris (2007) with the
inclusion of UFRO-I (Universidade Federal de Rondônia,
Porto Velho, Brazil).
Results
Moenkhausia parecis, new species
urn:lsid:zoobank.org:act:92DC6275-7ED7-46AE-97DF-
2C4F4FBA9FC4
Figs. 1-2
Holotype. MZUSP 116070, 77.9 mm SL, Brazil, Rondônia,
Vilhena, rio Madeira basin, upper rio Machado, tributary
of igarapé Piracolina, near road BR 364, 12°48’56.5”S
60°06’37.6”W, 14 Sep 2013, W. M. Ohara, D. B. Hungria
& B. S. Barros.
Paratypes. All form Brazil, Rondônia State, Vilhena.
ANSP 198235, 5, 27.8-48.7 mm SL; INPA 46708, 10, 28.0-
52.8 mm SL; MCP 48398, 10, 25.3-51.8 mm SL; MZUSP
116071, 57 (4 c&s, 28.8-42.6 mm SL), 22.0-65.5 mm SL;
UFRO-I 22721, 84, 16.2-67.3 mm SL (18 measured, 44.7-
77.9 mm SL); same data as holotype. MZUSP 115509, 47,
24.1-72.8 mm SL (12 measured, 44.0-71.6 mm SL), same
locality as holotype, 3 Sep 2014, W. M. Ohara & P. L.
Cunha. MZUSP 116072, 9, 23.0-59.6 mm SL; UFRO-I
22906, 7, 20.1-30.4 mm SL, same locality as holotype,
19 Jul 2013, I. da Costa. MZUEL 11836, 7, 22.9-60.6 mm
SL; MZUSP 117066, 8, 26.5-71.2 mm SL, same locality as
holotype, 12 Nov 2014, W. M. Ohara, F. C. P. Dagosta &
V. Giovannetti.
Diagnosis. Moenkhausia parecis is distinguished from all
congeners, except M. clorophthalma Sousa, Netto-Ferreira
& Biri n delli, 2010, some populations of M. cotinho
Eigen mann , 1908 (see Discussion), M. lineomaculata
Dagosta, Marinho & Benine, 2015, M. petymbuaba
Lima & Birindelli, 2009, and M. plumbea Sousa, Netto-
Ferreira & Birindelli, 2010 by the presence of a dark
blotch on the anterior portion of each scale of the second
to seventh longitudinal series (vs. pigmentation absent
or, when present, concentrated at the posterior margin of
scales, forming a reticulate pattern). Moenkhausia parecis
can be readily distinguished from all aforementioned
species by having completely blue eyes in life (vs. green
in M. clorophthalma, mostly green with some red in
M. petymbuaba, lower portion blue and upper portion
orange in M. lineomaculata, clear or red in M. cotinho,
and clear, with a longitudinal dark stripe in M. plumbea).
Additionally, it is distinguished from M. clorophthalma,
M. petymbuaba and M. plumbea by having 15-18 (rarely 18)
branched anal-n rays (vs. 18-24), from M. cotinho and M.
lineomaculata by having a smaller caudal-peduncle spot,
with only the base of the middle caudal-n rays pigmented
(vs. blotch larger, base of all caudal-n rays pigmented in
M. cotinho and M. lineomaculata, except the outermost
unbranched rays in some specimens of M. lineomaculata)
and by the absence of a light area preceding caudal-
peduncle spot (vs. presence of a light area preceding
caudal-peduncle spot). It can be further distinguished
from M. clorophthalma, M. petymbuaba and M. plumbea
by having a well-dened, round caudal-peduncle spot, that
does not extend to the tip of the middle caudal-n rays
(vs. caudal-peduncle spot absent or poorly dened in M.
clorophthalma and M. plumbea or caudal-peduncle spot
conuent with longitudinal stripe on body, reaching the
tip of middle caudal-n rays in M. petymbuaba).
Description. Morphometric data of the holotype and
paratypes presented in Table 1. Body compressed,
moderately deep. Greatest body depth anterior to vertical
through dorsal-n origin. Dorsal prole of head convex
from anterior tip of upper jaw to vertical through anterior
nostril; straight or slightly concave from that point to tip
of supraoccipital spine. Dorsal body prole convex from
tip of supraoccipital spine to base of last dorsal-n ray,
approximately straight from that point to adipose-n
insertion and slightly concave along caudal peduncle.
Ventral prole of body convex from anterior tip of dentary
to anal-n origin, straight along anal-n base and slightly
concave along caudal peduncle.
Mouth terminal, upper jaw slightly longer than lower
jaw. Posterior terminus of maxilla reaching vertical
through middle of pupil. Maxilla approximately at 45
degree angle relative to longitudinal axis of body. Nostrils
close to each other, anterior opening circular, posterior
opening crescent-shaped. Nostrils separated by narrow
skin ap.
Premaxillary teeth in two rows; outer tooth row with
3(2), 4*(20), or 5(12) tricuspid teeth; inner tooth row with
5*(34) teeth bearing three to ve cusps, symphyseal tooth
of inner series narrow, asymmetric, with four cusps.
Tooth cusps of the inner premaxillary row arranged in
semicircular line, directed inward. Maxilla with 2(8),
3*(21), or 4(5) teeth along its anterodorsal margin, bearing
three to ve cusps (Fig. 2); anterior tooth usually largest.
Dentary with 4*(31) or 5(2) larger tri- to pentacuspid teeth,
followed by a series of 9(1), 10(1), 11(1), or 12(1) diminutive
teeth, conical or tricuspid, considerably smaller than the
anterior larger teeth. Cusps of large dentary teeth arranged
in semicircular line, directed outward. Central cusp of all
teeth more developed than lateral cusps.

e1500XX39
W. M. Ohara & M. M. F. Marinho
Neotropical Ichthyology, 14(1): e150041, 2016
39
Fig. 2. Medial view of left side of premaxilla, maxilla and
dentary of Moenkhausia parecis, MZUSP 116071, paratype,
26.2 mm SL. Scale bar = 1 mm.
Scales cycloid, moderately large, circuli distributed over
whole area of scales; six to twenty radii well-dened and
slightly divergent posteriorly. Lateral line complete, slightly
curved downward, with 32(10) or 33*(20) perforated scales.
Longitudinal scale rows between dorsal-n origin and
lateral line 5*(30). Longitudinal scale rows between lateral
line and pelvic-n origin 4*(30). Median series of scales
along dorsal line between tip of supraoccipital spine and
dorsal-n origin 9(22) or 10*(6). Horizontal scale rows
around caudal peduncle 14*(30). Single row of 5(1), 6(7),
7*(7), 8(7), 9(4), or 10(1) scales covering base of anterior
most anal-n rays. Caudal-n lobes with small scales on
basal third, squamation slightly more extensive on ventral
lobe than on dorsal.
Dorsal-n rays ii,9*(29) or iii,8(2). Dorsal-n origin
approximately at midpoint of standard length, slightly
posterior to vertical through pelvic-n origin. First
unbranched dorsal-n ray half length of second or
less. Distal prole of dorsal n round. First dorsal-n
pterygiophore posterior to neural spine of 9th (4) vertebrae.
Adipose n present. Pectoral-n rays i,11*(17) or i,12(13). Tip
of adpressed pectoral n reaching vertical through pelvic-n
Fig. 1. Moenkhausia parecis new species, (a) holotype, MZUSP 116070, 77.9 mm SL (b) paratype, MZUSP 115509, 41.7 mm
SL, immediately after capture, upper rio Machado, rio Madeira basin, Rondônia, Brazil.

New Moenkhausia from the rio Madeira basin
Neotropical Ichthyology, 14(1): e150041, 2016
40
or igin or fall i ng just short of tha t point. Pelvic- n rays i,7(30).
Tip of adpressed pelvic n not reaching anal-n origin,
except in specimens smaller than 42.0 mm SL. Unbranched
anal-n rays iv(4). Branched anal-n rays 15*(5), 16(20),
17(6), or 18(3). Posterior unbranched and anterior branched
anal-n rays longest, subsequent rays gradually decreasing
in size. Distal margin of anal n slightly concave. Principal
caudal-n rays i,9,8,i*(28); caudal n forked, lobes somewhat
pointed and of similar size. Dorsal procurrent caudal-n rays
12(1) or 13(3), ventral procurrent caudal-n rays 11(4).
Total vertebrae 32(1) or 33(3): precaudal vertebrae 16(4)
and caudal vertebrae 17 (1) or 16(3). Supraneurals 4(3) or
5(1), slightly wider dorsally. Branchiostegal rays 4. First gill
arch with one (4) gill-raker on hypobranchial, 7(2) or 9(2) on
ceratobranchial, one (4) on cartilage between ceratobranchial
and epibranchial, and 6 (4) on epibranchial.
Table 1. Morphometric data of the holotype and paratypes
of Moenkhausia parecis. Paratype range includes the values
of the holotype. N = 30; S.D. = Standard Deviation.
Characters
Holotype Range Mean±S.D.
Standard length (mm) 77.9 41.7-77.9
Percentage of standard length
Depth at dorsal-n origin 38.7 35.6-40.1 38.0±1.1
Snout to dorsal-n origin 54.7 53.0-56.9 54.5±1.0
Snout to pectoral-n origin 30.1 29.6-33.0 31.4±0.9
Snout to pelvic-n origin 51.7 51.6-55.2 53.4±1.0
Snout to anal-n origin 71.9 67.6-72.7 70.6±1.3
Caudal peduncle depth 13.2 12.7-14.4 13.5±0.4
Caudal peduncle length 14.5 11.4-14.6 13.2±0.8
Pectoral-n length 21.8 20.0-24.4 22.7±1.0
Pelvic-n length 15.3 15.0-18.4 17.0±1.0
Pelvic-n origin to anal-n origin 21.6 17.8-21.6 19.5±1.0
Dorsal-n base 14.5 14.3-16.6 15.3±0.5
Dorsal-n length 24.0 24.0-30.1 27.2±1.5
Dorsal-n origin to caudal n origin 51.9 45.9-54.0 52.1±1.4
Anal-n base 22.2 22.0-25.0 23.3±0.9
Anal-n length 17.3 16.7-21.5 19.4±1.1
Posterior margin of eye to dorsal-n origin
40.9 38.1-41.0 39.5±0.8
Head length 29.0 28.6-32.2 30.9±0.9
Percentage of head length
Horizontal eye diameter 33.8 31.1-37.9 35.0±2.0
Snout length 26.6 24.5-30.1 27.3±1.4
Interorbital width 40.9 33.8-40.9 36.7±1.5
Upper jaw length 54.2 50.6-55.0 52.1±1.2
Color in alcohol. Overall ground color pale, with small dark
chromatophores covering the entire head and body, densely
concentrated on dorsal portion, gradually fading ventrally
(Fig. 1a). Dorsal midline of head and body dark brown.
Jaws, opercular and infraorbital areas densely pigmented
with small dark chromatophores. Opercular areas with
guanine. Humeral blotch vertically oriented, extending two
scale rows above and one or two scale rows below lateral
line. Dorsal portion of humeral blotch spanning three scales
in width; ventral portion narrower, spanning just over one
scale. Area posterior to humeral blotch followed by faint
and wide horizontal dark stripe spanning two scale rows
above lateral line that fades posteriorly on caudal peduncle;
horizontal dark stripe not conspicuous in specimens smaller
than 44.5 mm SL. Deeper and narrower longitudinal
dark stripe at horizontal septum, formed by underlying
chromatophores, extending from vertical through dorsal-n
origin to caudal peduncle. One dark blotch at the anterior
portion of each scale of the second to seventh dorsalmost
scale rows. Well-dened, black, round caudal-peduncle
spot, extending from posterior portion of caudal peduncle
to base of middle caudal-n rays, not extending to tip of n
rays. Caudal-peduncle spot not reaching upper and lower
margins of caudal peduncle and restricted to middle caudal-
n rays. All ns with scattered dark chromatophores. Distal
portion of interradial membranes of anal n with increased
concentration of dark chromatophores.
Color in life. Dorsal portion of head and body light
brown; ventral half yellowish (Fig. 1b). Eyes bright blue.
Longitudinal iridescent clear stripe at midline of body.
Second to seventh dorsalmost scale rows with brown
blotches on its anterior portion. Humeral blotch and caudal-
peduncle spot conspicuous. All ns intense orange to yellow.
Sexual dimorphism. No sexually dimorphic characters
were found among analyzed specimens.
Et y molog y. The specic name parecis refers to the Chapada
dos Parecis (plateau including the t ype locality), an important
watershed that separates tributaries of three basins: rio
Madeira, rio Tapajós and rio Paraguai. A noun in apposition.
Distribution. Moenkhausia parecis is known only from its
type locality, a headwater tributary of igarapé Piracolina,
itself a tributary of the upper rio Machado at Chapada dos
Parecis, rio Madeira basin, about 9 km south of Vilhena,
near the border of Rondônia and Mato Grosso States, Brazil
(Fig. 3). Moenkhausia parecis is possibly an additional
species endemic to the rivers draining the Chapada dos
Parecis (see list in Ohara & Lima, 2015).
Ecological notes. The type locality of Moenkhausia parecis
is located at 585 m above sea level on the Chapada dos Parecis.
It is a small “terra-rme igarapé” (= highland creek) with
little preserved riparian vegetation and surrounded by large
plantation elds (mostly soy and corn), near Vilhena, Mato
Grosso. It is a clear water stream 1.5-2.5 m wide and 0.3-0.8
m deep, with swift currents, and a bottom composed of sand
and dead leaves (Fig. 4). During snorkeling, Moenkhausia
parecis was observed in small groups of 10-15 individuals
swimming in midwater. Syntopic species included Ancistrus
verecundus Fisch-Muller, Cardoso, da Silva & Bertaco,
2005, Bryconops piracolina Wingert & Malabarba, 2011,

e1500XX41
W. M. Ohara & M. M. F. Marinho
Neotropical Ichthyology, 14(1): e150041, 2016
41
Cetopsorhamdia sp. 3 (cf. Bockmann & Slobodian, 2013:
25), Corydoras sp., Hyphessobrycon lucenorum Ohara &
Lima, 2015, Hyphessobrycon aff. melonostichos Carvalho &
Bertaco, 2006 and Pyrrhulina sp. The stomach contents of
the four (c&s) paratypes included ants, scales, unidentied
insect fragments, seeds, unidentied vegetal fragments and
sediments.
Fig. 3. Type locality (blue square) of Moenkhausia parecis,
a tributary of the igarapé Piracolina, upper rio Machado
drainage, rio Madeira basin, Brazil.
Fig. 4. Tributary of igarapé Piracolina, upper rio Machado,
Vilhena, Rondônia, Brazil, type locality of Moenkhausia
parecis.
Conservation status. Despite intensive and broad
collecting efforts in the rio Madeira basin during 2009 to
2013 (Queiroz et al., 2013) and recent surveys conducted
in the southeastern portion of Rondônia State and
northwest of Mato Grosso State undertaken in 2010-2011
an d 2013 -2 014, Moenkhausia parecis was only collected at
its type locality. Additionally, examination of several sh
collections failed to reveal additional specimens. Thus, it
is possible that the species is restricted to the upper rio
Machado, at the Chapada dos Parecis. The type locality of
M. parecis is a small forest fragment near Vilhena town
that is surrounded by farms. According to the Inter national
Union for Conservation of Nature (IUCN) categories and
criteria (IUCN Standards and Petitions Subcommittee,
2014), Moenkhausia parecis might be considered as
‘Vulnerable (D2)’, based on its occupation area (AOO)
apparently less than 20 km2 and the plausible future threat
(agricultural development and expansion of Vilhena town
around its very restricted distribution) that could lead the
species to become critically endangered or extinct.
Discussion
The traditional classication system of the Characidae
developed by Eigenmann (1917, 1918, 1921) delimited
several genera based on morphological characters such as
the form of the teeth, squamation of the caudal-n, presence
or absence of the adipose n, and length of the lateral line.
These characters were found subsequently to be highly
homoplastic within the Characidae (Weitzman & Fink,
1983; Mirande, 2010; Marinho et al., 2014; Dagosta et al.,
2014). As a consequence, Eigenmann’s classication scheme
resulted in the articial delimitation of many groups of
species.
The genus Moenkhausia still lacks a phylogenetic
denition. Recent cladistic analyses (Mirande, 2010;
Oliveira et al., 2011; Mariguela et al., 2013) have conrmed
previous suggestions of its non-monophyly (e.g. Fink, 1979;
Costa, 1994). Meanwhile, putative monophyletic groups
including members of Moenkhausia have been suggested
mainly based on color pattern and some of them conrmed
by cladistic studies (e.g. the “Moenkhausia oligolepis /M.
sanctaelomenae-species complex” (Benine et al., 20 09).
One of the most remarkable features of Moenkhausia
parecis is the presence of a dark blotch at the anterior portion
of each scale of the second to seventh scale rows. This color
patter n, which is relatively unusual within Characidae, is also
present in Moenkhausia chlorophthalma, M. lineomaculata,
M. plumbea, M. petymbuaba, and some populations of M.
cotinho. Such feature was used by Sousa et al. (2010) to
indicate a possible close relationship among the former three
species. Based on body coloration and aspects of external
morphology such as the relatively large head, the vertical
orientation of the humeral blotch, the round dorsal-n distal
margin, and the relatively short anal-n base, Moenkhausia
parecis is similar to these species and may be closely related

New Moenkhausia from the rio Madeira basin
Neotropical Ichthyology, 14(1): e150041, 2016
42
to them. However, such relationships are speculative and
the monophyly of this group of species should be tested in a
cladistic context.
A few other small characids possess similar
body coloration to Moenkhausia parecis, such as A.
maculisquamis Garutti & Britski, 1997, which is a member
of the Astyanax bimaculatus ( Li nnaeus, 1758) complex.
However, that species complex is dened by possession of
a black, horizontally ovate humeral spot, and two diffuse
vertical dark bars in the humeral region (Garutti & Britski,
1997; Garutti & Britski, 2000; Gar utti & Langeani, 2009),
neither of which occurs in Moenkhausia parecis. Therefore,
there is no further evidence of a close relationship of
the new species to members of this group. Two species
of Jupiaba Zanata, J. kurua Birindelli, Zanata, Sousa &
Netto-Ferreira, 2009 and J. meunieri (Géry, Planquette &
Le Bail, 1996) possess dark blotches on the anterior portion
of the body scales, as does Moenkhausia parecis. Birindelli
et al. (2009) used that color pattern to indicate a close
relationship between these species of Jupiaba. However,
Moenkhausia parecis lacks the synapomorphic features of
Jupiaba (Zanata, 1997; Zanata & Lima, 2005) including
the presence of pelvic bone anteriorly developed as a spine,
with its anterior portion free from musculature, and clearly
does not belong to Jupiaba.
As mentioned, series of dark blotches on the body
scales are also found in some populations of Moenkhausia
cotinho, a widespread species of the Amazon, Orinoco and
Essequibo basins. Members of Moenkhausia cotinho have
a light area anterior to a large dark blotch on the caudal-n
base. These caudal marks, along with dark pigmentation
concentrated on the distal border of the scales, forming a
dark reticulate pattern, characterizes the “Moenkhausia
oligolepis/M. sanctaelomenae-species complex” (Costa,
1994; Lima & Toledo-Piza, 200; Lima et al., 2007).
According to Lima & Toledo-Piza (2001) and Lima et
al. (2007), M. cotinho is closely related to this group of
species, despite not having the characteristic reticulate
pattern on the majority of the body. Sousa et al. (2010),
however, mentioned the presence of such reticulation on
the scales below the lateral line in M. cotinho, and also
noted the blotches on the anterior portion of the scales.
Given the divergent information regarding the
coloration of Moenkhausia cotinho and presence of a series
of dark blotches on body scales in some populations, by
which it resembles Moenkhausia parecis, we conducted
a broader examination of several lots of M. cotinho
deposited at MZUSP in order to better understand the
coloration pattern of the widespread species. According to
our investigations, the species varies in both the series of
blotches on the body scales and the reticulate color pattern.
Most analyzed specimens have small, approximately round
blotches located beneath the posterior portion of each scale
and over the base of the subsequent, especially dorsal to
the lateral line. It also possesses the reticulate pattern
on body, formed by a thin patch of dark pigmentation
on the posterior scale borders. This reticulation is more
conspicuous in adult specimens (e.g. MZUSP 106355,
107442, 109594, 115856). Other specimens possess only
small blotches on the scales, and lack reticulation (e.g.
MZUSP 7274, 100593) and others lack both patterns (e.g.
MZUSP 40372, 105307, 106825), resulting in an overall
pale body. Given the wide geographical distribution of
M. cotinho and the substantial color variation, a detailed
taxonomic revision should be conducted in order to clarify
whether we are dealing with a species complex. For the
purpose of the present contribution, all populations of
M. cotinho can be easily diagnosed from M. parecis by
having the caudal-peduncle blotch wide, reaching upper
and lower margins of caudal peduncle (vs. spot smaller, not
reaching upper and lower edges of caudal peduncle), and
by possessing a light area devoid of dark chromatophores
anterior to the caudal-peduncle spot, which is bright yellow
in life (see Dagosta et al., 2015, g. 5) (vs. pigmentation
pattern of body extending to the end of caudal peduncle,
not leaving a clear area anterior do the caudal-peduncle
spot; no distinct coloration in this region in life).
Comparative material. Brazil, except when noted. Astyanax
maculisquamis: MZUSP 48181, 72 paratypes, 35.3-76.4
mm SL, Mato Grosso, rio Madeira basin. Moenkhausia
clorophthalma: MZUSP 97092, 28 paratypes, 38.0-64.8 mm SL,
MZUSP 107307, 75, 23.0-38.2 mm SL, Pará, rio Xingú basin.
Moenkhausia cosmops: All from the rio Tapajós basin, Mato
Grosso State. MZUSP 93494, holotype, 42.9 mm SL. MZUSP
93495, 17 paratypes, 22.3-48.4 mm SL. MZUSP 93551, 3, 22.2-
31.5 mm SL. MZUSP 96042, 5, 37.3-50.7 mm SL. MZUSP
93552, 2, 17.2-25.4 mm SL. LIRP 8181, 3 of 6, 45.3-53.1 mm
SL. MZUEL 8750, 1, 33.5 mm SL. MZUEL 8749, 18 of 95,
19.5-30.8 mm SL. Moenkhausia cf. cotinho: MZUSP 7274, 9,
51.9-59.2 mm SL, Amazonas, rio Amazonas basin. MZUSP
58335, 8, 31.8-38.2 mm SL, MZUSP 109594, 29, 19.2-49.0 mm
SL, Amazonas, rio Negro basin. MZUSP 61956, 32, 28.6-37.3
mm SL, MZUSP 100593, 2, 47.3-50.5 mm SL, Mato Grosso, rio
Madeira basin. MZUSP 105318, 5, 43.3-61.2 mm SL, MZUSP
106321, 1, 38.5 mm SL, MZUSP 107442, 24, 39.4-53.6 mm
SL, MZUSP 107635, 9, 34.2-39.0 mm SL, MZUSP 107651, 21,
32.4-52.1 mm SL, MZUSP 115856, 19, 28.4-42.4 mm SL, Mato
Grosso, rio Tapajós basin. MZUSP 98316, 2, 39.7-53.6 mm SL,
MZUSP 99867, 3, 47.9-62.2 mm SL, Pará, rio Tapajós basin.
MZUSP 91408, 1, 49.0 mm SL, Mato Grosso, rio Xingu basin.
MZUSP 97192, 5, 31.8-41.7 mm SL, MZUSP 111592, 3, 40.7-
45.7 mm SL, Pará, rio Xingu basin. MZUSP 40372, 18, 23.1-
34.0 mm SL, Goiás, rio Tocantins basin. MZUSP 105307, 31,
25.6-47.4 mm SL, MZUSP 106825, 4, 32.4-34.5 mm SL, Pará,
rio Tocantins basin. Vene z u e l a: MZUSP 106355, 3, 17.3-42.1
mm SL, Amazonas, rio Orinoco basin. Moenkhausia diktyota:
MZUSP 62615, 9 paratypes, 28.4-52.3 mm SL, Amazonas, rio
Negro basin. Moenkhausia oligolepis: MZUSP 100669, 11, 34.6-
48.5 mm SL, Pará, rio Tapajós basin. MZUSP 115994, 1, 63.3
mm SL, Pará, rio Xingu basin. MZUSP 115631, 14, 31.1-37.8 mm
SL, Mato Grosso, rio Madeira basin. Moenkhausia petymbuaba:

e1500XX43
W. M. Ohara & M. M. F. Marinho
Neotropical Ichthyology, 14(1): e150041, 2016
43
MZUSP 30231, 5 paratypes, 44.8-51.1 mm SL, MZUSP 96867,
37, 35.7-49.2 mm SL, Pará, rio Xingú basin. Moenkhausia
plumbea: MZUSP 101435, 24 paratypes, 20.4-45.9 mm SL,
Pará, rio Tapajós basin. Moenkhausia pyrophthalma: MZUSP
45290, 7 paratypes, 20.4-30.0 mm SL, MZUSP 91286, 63, 23.3-
26.5 mm SL, Mato Grosso, rio Tocantins basin. MZUSP 89128,
24, 28.3-33.2 mm SL, Goiás, rio Tocantins basin. Moenkhausia
sanctaelomenae: MZUSP 47399, 9, 33.6-64.3 mm SL, Minas
Gerais, rio Jequitinhonha basin. MZUSP 89946, 9, 32.2-48.0
mm SL, Mato Grosso, rio Paraguai basin. MZUSP 115581, 2,
38.8-42.1 mm SL, Mato Grosso do Sul, rio Paraguai basin.
MZUSP 113917, 2, 45.0-45.5 mm SL, Bahia, rio São Francisco
basin.
Acknowledgements
We are grateful to Bruno Barros (Naturae), Digo
Hungria (GIA), Paula Cunha (UFRO) Fernando Dagosta
(MZUSP) and Victor Giovannetti (USP-IB) for help during
eldwork; to Carol Doria, Mariluce Messias, Ângela
Araujo (UFRO), Osvaldo Oyakawa and Michel Gianetti
(MZUSP) for curatorial assistance and loan of specimens.
We are indebted to Brian Sidlauskas, José Birindelli, and
two anonymous reviewers for their valuable comments
and suggestions on the manuscript. Part of the type series
was collected during an expedition funded by the South
American Characiformes Inventory (FAPESP 2011/50282-
7, http://www.projeto-saci.com). The authors are supported
by FAPESP (WMO: 2013/22473-8; MMFM: 2014/11911-7).
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Submitted April 03, 2015
Accepted Ja nuar y 21, 2016 by Brian Sidlauskas