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A new species of proboscoid thornycat, Rhynchodoras castilloi, is described from the Río Apure, Orinoco basin, Venezuela. The new species is distinguished from R. woodsi (Essequibo and Amazon basins minus Xingu and Tocantins basins) by having a simple gas bladder (vs. each posterior chamber of gas bladder expanded into elongate horn-like diverticulum) and tubercles punctate and abundant (vs. tubercles elongate, dash-like, and sparse). The new species is distinguished from R. xingui (Xingu and Tocantins basins) by having all three tympanal scutes weakly developed (vs. second and particularly third well developed, latter with medial carina), midlateral scutes modally 35 per side, range 34–36 (vs. 34, range 33–34), and anterior midlateral scutes relatively shallow, depth about one-fifth (vs. about one-third to one-quarter) of corresponding body depth, with weakly developed dorsal and ventral laminae lacking distinct serrations along posterior margins (vs. dorsal and ventral laminae of midlateral scutes well developed with conspicuously serrated posterior margins). The type species, R. xingui, is distinguished from R. woodsi by having a simple gas bladder (vs. with two posterior horn-like diverticula), midlateral scutes modally 34 per side, range 33–34 (vs. 35, range 34–37), and anterior midlateral scutes with conspicuous medial thorns (vs. thorns absent or weak, procumbent). Notable features of the genus are discussed, including jaw and gas bladder morphology, development of anterior nuchal plate, presence of multiple pores in skin beneath postcleithral process, and tubercle morphology and distribution. Shared derived characters suggest a sister-group relationship between Rhynchodoras and Rhinodoras plus Orinocodoras.
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New Species of Rhynchodoras from the ´o Orinoco, Venezuela,
with Comments on the Genus (Siluriformes: Doradidae)
JOSE
´L. O. BIRINDELLI,MARK H. SABAJ,AND DONALD C. TAPHORN
A new species of proboscoid thornycat, Rhynchodoras castilloi, is described from the
´o Apure, Orinoco basin, Venezuela. The new species is distinguished from R. woodsi
(Essequibo and Amazon basins minus Xingu and Tocantins basins) by having a simple
gas bladder (vs. each posterior chamber of gas bladder expanded into elongate horn-
like diverticulum) and tubercles punctate and abundant (vs. tubercles elongate, dash-
like, and sparse). The new species is distinguished from R. xingui (Xingu and Tocantins
basins) by having all three tympanal scutes weakly developed (vs. second and
particularly third well developed, latter with medial carina), midlateral scutes modally
35 per side, range 34–36 (vs. 34, range 33–34), and anterior midlateral scutes relatively
shallow, depth about one-fifth (vs. about one-third to one-quarter) of corresponding
body depth, with weakly developed dorsal and ventral laminae lacking distinct
serrations along posterior margins (vs. dorsal and ventral laminae of midlateral scutes
well developed with conspicuously serrated posterior margins). The type species, R.
xingui, is distinguished from R. woodsi by having a simple gas bladder (vs. with two
posterior horn-like diverticula), midlateral scutes modally 34 per side, range 33–34 (vs.
35, range 34–37), and anterior midlateral scutes with conspicuous medial thorns (vs.
thorns absent or weak, procumbent). Notable features of the genus are discussed,
including jaw and gas bladder morphology, development of anterior nuchal plate,
presence of multiple pores in skin beneath postcleithral process, and tubercle
morphology and distribution. Shared derived characters suggest a sister-group
relationship between Rhynchodoras and Rhinodoras plus Orinocodoras.
Se describe una especie nueva de bagre sierra con trompa probo´scide, Rhynchodoras
castilloi, del ´o Apure, cuenca del ´o Orinoco en Venezuela. La nueva especie se distingue
de R. woodsi (de las cuencas de los ´os Essequibo y Amazonas con la excepcio´n del rı´os
Xingu y Tocantins) en tener la vejiga de gas con una ca´mara simple y sencilla (vs. ca´mara
posterior dividido y alargada en forma de cuernos de vaca) y en poseer tube´rculos en
forma de puntos redondos abundantes (vs. solo unos pocos tube´rculos alargados en forma
de guio´n). La nueva especie se distingue de R. xingui (del ´os Xingu y Tocantins) en tener
las tres placas dermales timpanales pobremente desarrolladas (vs. la segunda y
especialmente la tercera bien formadas, y ese ultimo con un gancho medial) escudetes
mediolaterales modalmente35 en cada lado del cuerpo, rango 34–36 (vs. 34, rango 33–34),
y escudetes mediolaterales anteriores relativamente mas cortos verticalmente, su altura
solo comola quinta parte (vs. la tercera a cuarta parte) de la profundidad correspondiente
del cuerpo, con la´minas (alas) dorsal y ventrales pobremente desarrolladas, sin el margen
posterior conspicuamente aserrado (vs. laminas dorsal y ventrales de los escudetes
mediolaterales bien desarrolladas y con el margen posterior conspicuamente aserrado). La
especie tipo, R. xingui, se distingue de R. woodsi en tener una vejiga de gas simple (vs. con
dos cuernos posteriores), los escudetes mediolaterales modalmente 34, rango 33–34, en
cada lado del cuerpo (vs. 35, rango 34–37), y los escudetes mediolaterales anteriores con
ganchos obvios en el medio (vs. ganchos ausentes o debiles y procumbentes). Se describen
los aspectos notables del ge´nero, incluyendo la morfologı´a de la mandı´bula y la vejiga de
gas, el desarrollo de la placa nucal anterior, la presencia de numerosos poros en la piel por
debajo del proceso postcleitral, y la morfologı´a y distribucio´n de los tube´rculos. Los
caracteres compartidos derivados sugieren una relacio´ n filogene´tica de hermanas entre
Rhynchodoras yRhinodoras ma´s Orinocodoras.
THE rare and bizarre genus Rhynchodoras was
described by Klausewitz and Ro¨ ssel (1961)
based on two specimens from the upper Rio
Xingu (Amazon basin), Brazil. Its ichthyological
discovery dates back over 150 years and is
attributable to the famous naturalist–explorer
Alfred Russel Wallace. From 1850–1852 Wallace
traveled up the Rio Negro to the sources of this
Copeia, 2007(3), pp. 672–684
#2007 by the American Society of Ichthyologists and Herpetologists
river and the ´o Orinoco (Wallace, 2002), and
he took notes on and prepared detailed
drawings of the fishes collected. Although his
collections were lost at sea, many of his notes
and illustrations survived. Wallace’s drawing of
aspeciesofRhinodoras (originally labeled
‘‘Doras’’ and numbered 175) include the
following comments: ‘‘In a small specimen very
closely resembling this [Rhinodoras] in all other
particulars the head is higher towards the snout
which turns down and is produced in a sort of
proboscis which is received in a sort of trough
formed by the produced lower lip—the teeth
are similar but are also continued in a row
round the margin of each lip. Perhaps this is
the male and the above [Rhinodoras] being the
female.’’ (Wallace, 2002:332). This description
was certainly based on a specimen of Rhyncho-
doras, the only doradid genus in which the
snout ends in a vertically oriented, stiffened
proboscis formed by the forceps-like upper and
lower jaws.
Rhynchodoras includes two nominal species: the
type species R. xingui described by Klausewitz
and Ro¨ ssel (1961) from the upper Rio Xingu,
Brazil, and R. woodsi described by Glodek (1976)
from the upper Amazon basin, Ecuador. The
genus is diagnosed from other Doradidae by its
modified jaws forming a vertical proboscis-like
bill, relatively small eyes (diameter 5.6–8.6%of
head length), dorsal-fin spine with proximal
teeth retrorse, and ventral surface of coracoid
without bony crest separating muscles used to
move the pectoral-fin spine (i.e., abductors super-
ficialis and arrector ventralis). Rhynchodoras is also
distinguished by a number of non-exclusive
characteristics: head, body, and fins variably
roughened with minute tubercles, adipose fin
thick and elongate (continuing anteriorly more
or less to midpoint between posterior base of
dorsal fin and that of adipose fin), presence of
bony plates along the dorsal and ventral midline
of caudal peduncle (‘‘modified fulcra’’ of
Eigenmann, 1925:336), and absence of anterior
nuchal plate in adults (not confirmed for R.
xingui).
Bottom trawling in the channels of large rivers
(e.g., Calhamazon Project led by John Lundberg)
has obtained specimens of Rhynchodoras as deep
as 35 m in the Rio Purus. These recent collec-
tions in the Amazon basin and similar efforts in
the Orinoco have yielded a great deal of new
material that has uncovered the presence of
a third species. This paper describes a new
species of Rhynchodoras from the Orinoco basin,
discusses the taxonomy, morphology, and phylo-
genetic relationships of the genus, and provides
a key to the three nominal species.
MATERIALS AND METHODS
Measurements were made to the nearest
0.1 mm using dial calipers; methodology and
terminology follow Sabaj (2005) with the follow-
ing additions and exceptions: head length 5
distance from snout tip to dorsal-most point of gill
opening; body depth at anal-fin origin 5vertical
distance through anal-fin origin to dorsal margin
of adipose fin; caudal-peduncle length 5distance
from posterior base of anal fin to vertical through
posterior margin of hypural plates (same point to
which SL is taken); dorsal-spine length 5distance
from point on spine even with dorsal margin of
body to distal tip when erect; snout length 5from
tip of snout to anterior margin of iris; eye
diameter 5horizontal diameter of iris (depig-
mented skin surrounding eye excluded); opercle
width 5distance between dorsal-most points of
gill openings; nuchal shield width 5minimum
width of nuchal shield; maxillary-barbel length 5
from inferior base of barbel (where it meets labial
tissue) to distal tip; mental barbel lengths 5from
base of inner (or outer) mental barbel to distal tip.
Standard length (SL) is expressed in mm. All
other measurements are expressed as percentage
of SL, except subunits of head (expressed as
percentage of head length).
Midlateral scute counts were taken on the left
side of the body and began with the infranuchal
(scute attached dorsally to posterior nuchal plate
and internally to first rib). Osteological counts
(i.e., branchiostegal rays, pleural ribs, and
vertebrae) were restricted to cleared-and-stained
specimens (abbreviated CS) prepared according
to the procedures of Taylor and Van Dyke
(1985). Vertebral counts included all vertebrae
with compound caudal centra (PU1 +U1)
counted as a single element. Museum abbrevia-
tons follow Leviton et al. (1985) with the
addition of MEPN for Museo de Zoologı´a,
Departamento de Ciencias Biolo´ gicas, Escuela
Polite´ cnica Nacional, Quito, Ecuador.
Rhynchodoras castilloi, new species
Figure 1, Table 1
Holotype.—MCNG 54510, 79.8 mm, Venezuela:
Barinas: Can˜o Bravo, Apure–Orinoco Dr., about
60 km west-northwest of San Fernando de Apure,
8u09N, 67u599W, 7 March 2001, O. Castillo, G.
Cortes, J. Escalona, and C. Montan˜a.
Paratypes.—Venezuela: Apure: MCNG 45977, 1, ´o
Apure, Orinoco Dr., in front of Las Vegas,
downstream from airport in San Fernando de
Apure, 29 Aug. 1986, O. Castillo et al., OC86-01;
INPA 25826, 2, 31.5–32.5 mm, Can˜o Bucaral,
Arauca–Orinoco Dr., south of San Fernando de
BIRINDELLI ET AL.—NEW RHYNCHODORAS 673
Fig. 1. Lateral, dorsal, and ventral views of Rhynchodoras castilloi, MCNG 54510, holotype, 79.8 mm SL
(scale bar equals 1 cm). Photos by M. Sabaj.
674 COPEIA, 2007, NO. 3
Apure, 7u37960N, 67u369540W, 9 March 2005, O.
Castillo et al.; MCNG 52609, 11, 29.5–34.8 mm,
MHNLS 18844, 2, 29.3–35.9 mm, UF 162301, 2,
31.3–32.5 mm, same data as INPA 25826. Barinas:
ANSP 181181, 3, 47.0–56.9 mm, AUM 44237, 1,
51.6 mm, FMNH 117222, 2, 47.2–63.3 mm,
MBUCV 32900, 2, 41.3–58.0 mm, MCNG 49338,
2, 34.1–41.7 mm, MCNG 49301, 2, and MZUSP
88604, 2, 39.1–60.6 mm, 1 CS, 45.5 mm, same data
as holotype; MCNG 49400, 1, 47.6 mm, same
locality as holotype, 29 March 2001, G. Cortes and
J. Escalona; MCNG 49465, 1, same locality as
holotype, 31 March 2001, G. Cortes and J. Escalona.
Non-type material.—Venezuela: Apure: MBUCV
15212, 1, ´o Apure, Orinoco Dr., in front of
the Fluvial Command of National Guard in San
Fernando de Apure, 15 May 1985, O. Castillo, D.
Taphorn, and L. Nico; MCNG 54511, 1, ´o
Apure, Orinoco Dr., San Fernando de Apure, 15
Feb. 1982, L. Astudillo, N. Ortia, and P. Jime´nez,
MAC-II-82-3; MCNG 54512, 1, ´o Apure, Or-
inoco Dr., in front of Jarina, 18 June 1983, F.
Provenzano, O. Castillo, L. Astudillo, C. Marrero,
and D. Arana; MCNG 54513, 1, ´o Apure,
Orinoco Dr., in front of Jarina Lagoon, 14 May
1985, O. Castillo, D. Taphorn, and L. Nico.
Diagnosis.—Rhynchodoras castilloi (Fig. 1) is distin-
guished from R. xingui (Fig. 2A) by having all
three tympanal scutes weakly developed (vs.
second and particularly third well developed,
latter with medial carina), midlateral scutes 34 (n
52), 35 (10), 36 (2) (vs. 33 [1] or 34 [3]), and
anterior midlateral scutes relatively shallow,
depth about one-fifth of corresponding body
depth, and with dorsal and ventral laminae
weakly developed, lacking distinct serrations
along posterior margins (vs. depth about one-
third to one-quarter of corresponding body
depth, and dorsal and ventral laminae well
developed with conspicuously serrated posterior
margins). Rhynchodoras castilloi is distinguished
from R. woodsi (Fig. 2B) by having a simple swim
bladder (Fig. 3B; vs. each posterior chamber of
gas bladder expanded into elongate horn-like
diverticulum, Figs. 3C, 3D), and tubercles punc-
tate and abundant (vs. tubercles elongate, dash-
like, and sparse).
Description.—See Table 1 for morphometric data.
Body elongate, moderately compressed, greatest
depth at dorsal-fin origin, gently tapering to
slender caudal peduncle. Ventral surface weakly
flattened to somewhat rounded (convex). Head
elongate, laterally compressed, dorsal profile
evenly oblique from dorsal spine to posterior
nares, then curving abruptly downward as bluntly
rounded snout that continues below ventral
profile of head as vertically oriented premaxillae.
Eyes very small (diameter 6.6–8.6%of head
TABLE 1. MORPHOMETRIC DATA FOR Rhynchodoras castilloi, NEW SPECIES.
Holotype nMean Range SD
Standard length (mm) 79.8 15 51.5 34.1–79.8
Percentages of SL
Predorsal distance 36.8 14 36.7 34.5–40.5 1.52
Prepectoral distance 26.6 14 25.6 24.0–28.1 1.1
Head length 30.1 14 29.0 27.7–30.5 0.76
Body depth at dorsal-fin origin 23.1 14 23.1 21.7–24.4 0.79
Body depth at anal-fin origin 17.2 14 17.6 16.6–19.4 0.8
Depth of caudal peduncle 6.1 14 6.5 6.1–7.0 0.24
Length of caudal peduncle 17.9 14 18.6 17.2–19.9 0.87
Dorsal-fin spine length 19.6 14 20 19.2–21.1 0.64
Pectoral-fin spine length 19.7 14 22.3 19.7–24.8 1.57
Anal-fin base length 12.7 14 13.3 12.2–14.7 0.84
Adipose-fin base length 25.1 14 24.2 19.0–27.0 1.99
Depth of the tenth midlateral scute 5.1 14 5.3 4.6–6.2 0.4
Percentages of HL
Snout length 53.8 14 52.8 48–56.1 1.88
Eye diameter 7.5 14 7.9 6.6–8.6 0.64
Interorbital length 16.7 14 19.2 16.7–21.3 1.64
Opercle width 45.8 14 52.1 45.8–56.8 2.54
Nuchal shield width 25.4 14 28.6 25.4–33.1 2.02
Cleithral width 67.9 14 71.7 67.9–76.7 2.89
Mental barbel length 30.4 14 35.0 30.3–40.2 2.99
BIRINDELLI ET AL.—NEW RHYNCHODORAS 675
length), covered by skin, positioned dorsolater-
ally and slightly anterior to midpoint between
snout tip and dorsal-spine origin. Jaws elongate,
vertically oriented, opening downward with long,
narrow gape. In lateral view, premaxillae more or
less straight, dentaries gently curved posteriorly
away from premaxillae and finishing even with or
slightly more ventral than dentaries (premaxilla
length 88–100%of dentary length). In ventral
view, lower jaw trough-shaped, opening towards
planar upper jaw to form a hemicircular channel.
Both jaws with tooth patches completely fused;
small acicular teeth arranged in a series of
parabolic rows decreasing in size and concentric
with outer margins of jaws. Maxilla small, located
aside base of premaxilla and supporting maxil-
lary barbel. Labial tissue thick and fleshy,
particularly around lower jaw.
Anterior and posterior nares surrounded by
short tubular skin; anterior nares about equidis-
tant between snout tip and posterior nares;
posterior nares larger than anterior, located
more or less at midpoint between snout tip and
center of eye. Cephalic shield with shallow yet
distinct medial groove that begins at or just
posterior to transverse plane through anterior
nares and finishes at posterior margin of middle
nuchal plate (groove usually with brief hiatus at
middle of supraoccipital). Single interorbital
fontanel elongate, narrow oval shape, bordered
by frontals posteriorly and laterally and meseth-
moid anteriorly. Nuchal foramina absent. Ante-
rior nuchal plate absent in cleared-and-stained
adult (45.5 mm SL) leaving straight transverse
suture between middle nuchal plate and supraoc-
cipital (condition as in R. woodsi,Fig.4A).
Epioccipital with posterior process long and
narrow, but not reaching infranuchal scute (tip
finishes below center of tympanal area). Nuchal
portion of cephalic shield transversely arched,
triangular roof-shape in cross-section. Eight
branchiostegal rays. Nine pairs of ribs, first pair
conspicuously larger than others and laterally
attached to medial face of infranuchal scute.
Forty-one vertebrae, sixth and seventh fused into
complex vertebrae.
Three pairs of barbels. Maxillary barbel simple,
without fimbriae, but with narrow tapering flap
along medial margin imparting dorsoventrally
flattened shape to entire structure; surface with
small papillae; distal tip reaching or falling just
short of ventral-most point of gill opening.
Mental barbels simple, inserted immediately
posterior to base of vertically oriented dentary;
Fig. 2. Lateral views of previously described Rhynchodoras. (A) R. xingui, SMF 5281, holotype, 63 mm SL;
(B) R. woodsi, FMNH 77008, holotype, 110.4 mm SL (scale bar equals 1 cm). Photos by S. Traenkner and M.
Littmann, respectively.
676 COPEIA, 2007, NO. 3
proximal portions of mental barbels conjoined to
point slightly beyond terminus of dentary; inner
mental barbel finishing slightly beyond outer.
Postcleithral process narrow, elongate with
pointed tip (lanceolate shape); surface flush with
body (margins inconspicuous). Ventral portion
of pectoral girdle (including posterior coracoid
processes) not exposed, covered with skin;
posterior coracoid processes short, extending to
slightly beyond insertion of pectoral fin. Pectoral
fin with elongate slit-like axillary pore. Skin
beneath entire length of postcleithral process
perforated with numerous smaller round pores.
Dorsal fin I,6; pectoral fin I,8; pelvic fin i,6;
anal fin iii–iv,8–9; caudal fin i,7+8,i. Dorsal-fin
origin located at about one-third body length
from snout tip. Dorsal-fin spine strong, laterally
compressed, and gently curved backward over
entire length with distal cartilaginous (break-
away) tip. Anterior margin of dorsal spine with
moderate teeth; proximal teeth small, crowded,
weakly retrorse; teeth becoming larger, well-
spaced, and more antrorse distally. Posterior
margin of dorsal spine with strong, well-spaced,
retrorse teeth larger than those along anterior
margin. Bony tip of adpressed dorsal fin reaches
to slightly beyond vertical through pelvic-fin
origin. Pectoral-fin spine strong, dorsoventrally
flattened, gently curved backward along anterior
margin with distal cartilaginous tip (spine length
equal to or slightly greater than that of dorsal
spine). Anterior margin of pectoral spine with
moderate teeth becoming slightly larger and
more antrorse distally; posterior margin with
strong retrorse teeth larger than those along
anterior margin. Pelvic fin triangular with weakly
rounded tip and relatively straight posterior
Fig. 3. Gas bladder morphology in Rhynchodoras
(left column ventral view, right column dorsal view).
(A) R. xingui, SMF 5282, paratype, 44.5 mm SL; (B)
R. castilloi, ANSP 181181, paratype, 58.3 mm SL; (C)
R. woodsi, ROM 62601, 44.2 mm SL; (D) R. woodsi,
ANSP 181042, 72.5 mm SL (scale bar equals 1 mm).
Fig. 4. Dorsal view of neurocranium in Rhynchodoras woodsi. (A) Adult, MZUSP 57316, 44.7 mm SL,
anterior nuchal plate absent; (B) juvenile, MZUSP 56872, 23.1 mm SL, anterior nuchal plate present. ANP
5anterior nuchal plate, APA 5autopalatine, DFS 5dorsal-fin spine, EPO 5epioccipital, FON 5anterior
cranial fontanel, FRO 5frontal, INS 5infranuchal scute, LAC 5lacrimal, LET 5lateral ethmoid, MES 5
mesethmoid, MNP 5middle nuchal plate, NAS 5nasal, pEPO 5epioccipital process, PMX 5premaxilla,
PNP 5posterior nuchal plate, PTE 5pterotic, SOC 5supraoccipital, SPC 5supracleithrum, SPH 5
sphenotic, SPI 5dorsal-locking spine.
BIRINDELLI ET AL.—NEW RHYNCHODORAS 677
margin when extended; origin near midpoint of
body, slightly posterior to vertical through tip of
adpressed pectoral spine. Anal fin prominent,
triangular with distal margin straight when
extended and vertical to body axis (margin
appearing weakly emarginate when fin partially
folded); first branched ray usually longest
(length greater than fin base). Caudal fin
distinctly forked with moderately pointed lobes;
lower lobe slightly larger than upper. Upper and
lower procurrent caudal-fin rays grading into
a series of flat, laterally expanded and weakly
overlapping plates; dorsal plates finish at or near
base of adipose fin and ventral plates finish
slightly before anal fin. Total count of dorsal
procurrent rays and plates 17–20 (mode 18 and
19); total count of ventral procurrent rays and
plates 18–21 (mode 18). Adipose fin with long
thick base, moderately deep and tapering ante-
riorly as fleshy keel to point slightly posterior to
tip of adpressed dorsal spine; distal free margin
thin and rounded.
Head, body, and fins covered by minute
tubercles. Tubercles most abundant on dorsal
portions of head and body and on adipose fin.
Tubercles almost always punctate, appearing as
minute dots (one specimen with a few tubercles
appearing as longer dashes).
Lateral line ossified with complete series of
scutes. First three scutes (tympanal, situated
between nuchal shield, postcleithral process, and
infranuchal scute) very small and inconspicuous,
without medial thorns in adults (third tympanal
scute may have medial thorn in small juveniles).
Infranuchal scute (first midlateral scute) tall,
without medial thorn in adults (thorn sometimes
present in juveniles). Infranuchal scute contacting
posterior nuchal plate dorsally and first rib
internally, but not contacting postcleithral process
ventrally. Postinfranuchal midlateral scutes taller
than wide, each with distinct medial thorn (thorns
largest on caudal peduncle), and shallow dorsal
and ventral laminae (wings) lacking conspicuous
serrations along posterior margins; depth of
scutes nearly uniform (becoming slightly shal-
lower posteriorly), covering about one-fifth of
body depth anterior to anal-fin origin. Midlateral
scutes (including infranuchal) per side: 34 (n5
2), 35 (10), or 36 (2).
Gas bladder (Fig. 3B) with abbreviated cordi-
form shape (width slightly greater than length),
reduced size (posterior chambers smaller than
anterior chamber), and occupying relatively
small portion of body cavity. Posterior chambers
without terminal horn-like diverticula.
Coloration in alcohol.—Dorsal and lateral surfaces
of head and body with light brown ground color
and heavily mottled with numerous dark brown
spots small to moderate in size; mottling stronger
on dorsal sides above midlateral scutes (Fig. 1).
Dark mottling sometimes loosely patterned (par-
ticularly in juveniles), forming three wide in-
completely pigmented bars on sides: first below
dorsal fin (finishing midlaterally), second below
adipose fin (finishing at anal-fin base), and third
on caudal peduncle. First and second bars joined
dorsally and laterally along dorsal laminae
(wings) of midlateral scutes, leaving relatively
pale lenticular patch on dorsal lateral side (above
pelvic fin). Second bar continues dorsally across
central portion of adipose-fin base (anterior-most
base and distal free lobe of adipose fin relatively
pale). Pale chevron (V-shaped saddle) on poste-
rior margin of nuchal shield (middle and
posterior nuchal plates) straddling anterior
dorsal-fin base. Ventral surfaces of head and
body either completely pale (some juveniles) or
with few brown spots scattered on abdomen and
sometimes gular region. Most specimens with
a conspicuous dark oblique streak immediately
below eye along infraorbitals from lacrimal to
sphenotic bones. Maxillary barbels pale with dark
brown spots near base; mental barbels complete-
ly pale or sometimes with a few light brown spots
near base.
All fins with pale yellow ground color and
highly mottled with dark brown spots, particular-
ly in adults. Dark mottling heaviest on basal
portions of dorsal, paired, and anal fins, becom-
ing less pronounced distally (often leaving pale
margin). Caudal fin darkly mottled, often with
wide dark crescent-shaped vertical band on base
(sometimes bordered posteriorly by a narrower
pale band); central portions of upper and lower
lobes mottled, distal margins relatively pale.
Distribution and ecology.—Known only from a few
sites in the middle to lower ´o Apure (Orinoco
basin) in the llanos region of Barinas and Apure
states, Venezuela (Fig. 5). All specimens were
collected by bottom trawling. Carvajal (2005)
reported diet composed completely of Trichop-
tera for two specimens.
Etymology.—Named in honor of Venezuelan bi-
ologist Otto E. Castillo G., who collected much of
the type material, for his lifelong dedication to
the study and stewardship of his country’s rich
diversity of freshwater fishes.
DISCUSSION
Taxonomic comments on Rhynchodoras.—Klause-
witz and Ro¨ ssel (1961) proposed the genus
Rhynchodoras for their new species, R. xingui
678 COPEIA, 2007, NO. 3
(Fig. 2A), based on two specimens (SMF 5281, SL
63 mm and SMF 5282, SL 45 mm) collected by
anthropologist and fish hobbyist Harold Schultz
from the upper Xingu basin, Brazil (Amazon
drainage, precise locality not known, Fig. 5).
They diagnosed the genus on the basis of its
unique jaw morphology and a number of other
features including head shape, eye size, fin and
barbel morphology, midlateral scutes, and cau-
dal-peduncle plates. The species was then di-
agnosed on the basis of its jaw morphology and
coloration. Two additional specimens of R. xingui
(INPA 26540) were recently discovered in a large
collection of Rhinodoras from the lower Rio
Tocantins, Brazil.
Glodek (1976) described a second species,
Rhynchodoras woodsi (Fig. 2B), from the Maran˜on
basin (Amazon drainage), Ecuador (Fig. 5). Glo-
dek (1976:43–44) rediagnosed the genus on the
sole basis of its ‘‘forcep-like’’ jaws. Although Glodek
(1976:45) did not examine the types of R. xingui,he
distinguished R. woodsi on the basis of its ‘‘smaller
eye, 16.4–24 in head length (vs. 12.5–13 in R.
xingui), dentary projecting ventrally past premaxil-
lary by slightly more than one eye diameter (vs. of
approximately equal length in R. xingui)’’, and two
tympanal scutes (vs. three in R. xingui).
Two of the diagnostic characters reported by
Glodek (1976) are not reliable for separating R.
xingui and R. woodsi. The relative lengths of the
jaws vary in both R. woodsi and R. xingui (e.g., jaws
nearly equal in holotype vs. dentary projecting
ventrally past premaxilla in paratype). Glodek
(1976) also reported two tympanal scutes in R.
woodsi. All specimens examined here have three
tympanal scutes (the first is small and often
covered with skin in all three species).
The difference in eye size does appear to
distinguish the two Amazonian species. Speci-
mens of R. woodsi examined here have a smaller
eye: diameter 5.6–7.5%of head length (n523)
vs. 8.3%in paratype of R. xingui (our measure) or
7.65–8%(as reported by Klausewitz and Ro¨ ssel,
1961), and 8.0–8.2%in two specimens from the
Tocantins. The number of midlateral scutes may
also distinguish specimens of R. woodsi and R.
xingui. Specimens of R. woodsi examined here
have 34 (n53), 35 (13), 36 (10), or 37 (1)
midlateral scutes (including infranuchal), where-
as the four specimens of R. xingui have 33 (1)
and 34 (3). The best character for separating the
two Amazonian species is the morphology of the
gas bladder: simple, without posterior diverticula
in R. xingui (Fig. 3A) vs. each posterior chamber
expanded into elongate horn-like diverticulum
in R. woodsi (Figs. 3C, 3D).
Comments on Rhynchodoras morphology.—The
complexity of gas bladder morphology in dor-
adids was noticed early by Kner (1853) who
Fig. 5. Distributions of species of Rhynchodoras.
BIRINDELLI ET AL.—NEW RHYNCHODORAS 679
introduced six new species on the sole basis of
illustrations of disembodied gas bladders. Later,
Eigenmann (1925) gave special attention to gas
bladder morphology in his remarkable mono-
graph of Doradidae, and used it to propose a new
genus, Hoplodoras. Risso and Morra (1964) also
used gas bladder morphology to distinguish their
new genus and species Parapterodoras paranensis.
In both of these cases, however, the reported
differences in gas bladder morphology are
attributable to ontogenetic change (Higuchi,
1992; pers. obs.). Nevertheless, gas bladder
morphology among doradids can be diagnostic
at the level of genera (Eigenmann, 1925; Sabaj,
2005) and species, as it is in Rhynchodoras, even
when ontogenetic changes are taken into ac-
count.
The gas bladder is reduced in all three
Rhynchodoras (Fig. 3) and in R. woodsi each
posterior chamber is expanded into a large
straight horn-like diverticulum (Figs. 3C, 3D). A
reduced gas bladder with similar pair of posterior
diverticula also is found in Leptodoras (Sabaj,
2005) and some auchenipterids such as Ageneio-
sus (Britski, 1972; Walsh, 1990, as ceacae). In
Leptodoras the gas bladder has additional ante-
rolateral diverticula (absent in Rhynchodoras) and
in Ageneiosus the gas bladder is encapsulated in
bone (Walsh, 1990).
In Doradidae and Auchenipteridae (including
ageneiosids) the anterior nuchal plate is primi-
tively large and shares a narrow to broad suture
with the epioccipital (Ferraris, 1988; Higuchi,
1992; pers. obs.). Alternatively, the anterior
nuchal plate is variable in size, reduced (i.e.,
bordered by supraoccipital and middle nuchal
plate) or even lost in some taxa. In Doradidae,
reduction of the anterior nuchal plate occurs in
a variety of fimbriate-barbel taxa: Oxydoras eigen-
manni, Nemadoras elongatus, N. hemipeltis, some
Opsodoras, Hassar, Hemidoras, Anduzedoras oxy-
rhynchus, and Leptodoras praelongus. The anterior
nuchal plate is totally absent and apparently lost
in Nemadoras trimaculatus, N. humeralis and
Opsodoras ternetzi. Some doradids, such as Oxy-
doras niger and Doras fimbriatus, are polymorphic
for this character with the anterior nuchal plate
either fully developed or reduced.
As in adult Rhynchodoras (Fig. 4A), the anterior
nuchal plate is absent in the doradid Physopyxis
and several genera of auchenipterids. Higuchi
(1992) and Sousa and Rapp Py-Daniel (2005)
speculated that the anterior nuchal plate is fused
to the middle nuchal plate in Physopyxis, whereas
Soares-Porto (1998) speculated that it is fused
with the supraoccipital in auchenipterids Centro-
mochlus, Glanidium, and Gelanoglanis.InRhyncho-
doras woodsi the anterior nuchal plate is present
but small (Fig. 4B) in two cleared-and-stained
juveniles (23.1 and 26.0 mm SL), whereas in two
cleared-and-stained adults (44.7 and 47.6 mm
SL) the anterior nuchal plate is absent (Fig. 4A).
This suggests not fusion but ontogenetic re-
duction and loss of the anterior nuchal plate in
R. woodsi. The anterior nuchal plate is absent in
a cleared-and-stained adult of R. castilloi
(45.5 mm SL). The condition of this plate could
not be confirmed in juvenile R. castilloi and R.
xingui due to lack of specimens for clearing and
staining.
A remarkable feature that may be unique to
doradids among siluriforms is the occurrence of
numerous pores crowded in the skin below the
postcleithral process (pectoral region) and im-
parting a sponge-like appearance. This porous
pectoral patch of skin may be glandular, and it is
conspicuously developed in several fimbriate-
barbel doradids such as Anduzedoras oxyrhynchus,
Doras, Hassar, some Leptodoras, most Nemadoras,
Opsodoras ternetzi, and Trachydoras (Sabaj, 2002;
pers. obs.). The porous pectoral patch is well
developed in Rhynchodoras but absent in all other
non-fimbriate taxa. It is uncertain whether these
porous pectoral patches evolved more than
once among doradids or have been lost multiple
times.
The skin of Rhynchodoras is roughened with
small pale mounds and ridges interpreted as the
unculiferous tubercles described by Roberts
(1982). The tubercles are evident in juveniles
and adults, and are therefore unlikely to be
associated with reproduction. Similar structures
are reported for many other catfishes in a diverse
array of families: Akysidae, Amphiliidae, Aspre-
dinidae, Loricariidae, Mochokidae, Sisoridae
(Roberts, 1982), Nematogenyidae, Pimelodidae,
Trichomycterdiae (Arratia and Huaquin, 1995),
Auchenipteridae (Ferraris and Vari, 1999),
Erethistidae (Ng, 2005), and Heptapteridae and
Pseudopimelodidae (pers. obs.). In Rhynchodoras,
the surface of these tubercles may be keratinized
to form a thin cuticle as in mochokid catfishes
(Wiley and Collette, 1970). Among doradids
(e.g., Leptodoras, Rhinodoras), the size, shape,
distribution, and abundance of tubercles have
taxonomic implications as in other catfishes such
as mochokids (Roberts, 1989; Ng, 2004).
The jaw morphology of Rhynchodoras is the
most striking and useful character for diagnosing
the genus. The modifications involve not only
the premaxillae and dentaries, but also the
mesethmoid (i.e., narrow, elongate, with small
anterior notch that articulates with the premax-
illae) and the articular (elongate and curved
ventrally). Such modifications appear to be
unique among catfishes.
680 COPEIA, 2007, NO. 3
In Rhynchodoras the dorsal and ventral procur-
rent rays of the caudal fin grade into a series of
flat, laterally expanded, and weakly overlapping
plates that continue to (or very near to) the base
of adipose and anal fin, respectively, thereby
framing the caudal peduncle dorsally and ven-
trally. This condition is also present in Agamyxis,
some Anadoras, Franciscodoras, Orinocodoras, Platy-
doras, and Rhinodoras.InAgamyxis the lateral
margins of the procurrent plates are ornamented
with raised spines (vs. absent in other taxa). The
anterior procurrent caudal-fin rays are modified
into plates to a lesser degree in a few additional
doradids. For example, in Astrodoras, Doras
fimbriatus, and some Oxydoras eigenmanni, the
anteriormost dorsal and ventral procurrent ray
may be slightly enlarged and moderately flat-
tened to form a single lenticular plate that may
or may not reach the base of the adipose and
anal fin, respectively. In Hypodoras, the anterior-
most dorsal and ventral procurrent elements
reach the base of the adipose and anal fin,
respectively, and are rounded, plate-like, and
distinctly enlarged relative to the following
elements that grade into procurrent rays. Plates
also occur middorsally and midventrally on the
caudal peduncle in Lithodoras; however, these
plates are irregularly shaped, non-overlapping,
and are not modified procurrent rays.
Comments on Rhynchodoras relationships.—Alfred
Russel Wallace noticed a resemblance between
Rhinodoras and Rhynchodoras,andquestioned
whether the differences were gender related
(Rhynchodoras being the male). Higuchi (1992)
hypothesized doradid relationships using a cladis-
tic analysis of morphological characters. Al-
though Higuchi (1992) did not include Rhynch-
odoras in his analysis, he did note that
Rhynchodoras and Rhinodoras share similarities in
the shape of the cephalic shield and in external
postcranial morphology. Both genera also exhib-
it similar patterns of pigmentation (i.e., mottled
with three dark bars on body and dark band on
caudal-fin base).
We corroborate Higuchi’s speculation and
consider Rhynchodoras to be related to a clade
composed of Rhinodoras plus the monotypic
Orinocodoras eigenmanni. These taxa share two
characters that appear to be uniquely derived in
Doradidae: medial inferior crest present on
ventral face of hyomandibula, and autopalatine
long, reaching to but not beyond anterior
margin of orbit. They also share a number of
characters that are restricted to a few taxa in
Doradidae: aortic channel partially or completely
open, caudal peduncle framed with plates de-
rived from procurrent caudal-fin rays, dorsal-fin
spine strong, curved, and with large well-spaced
teeth anteriorly and posteriorly, and adipose fin
thick and prolonged anteriorly as fleshy keel.
In addition to its highly modified jaws,
Rhynchodoras may be diagnosed by three char-
acters that appear to be unique (autapomorphic)
among doradids: proximal teeth on dorsal-fin
spine retrorse, transition between ventral sur-
faces of posterior coracoid process and anterior
limb of coracoid smooth, not marked by thin
crest separating muscles abdutors superficialis and
arrector ventralis, and eye extremely reduced,
diameter 5.6–8.6%of head length.
KEY TO THE SPECIES OF Rhynchodoras
1a. Posterior chambers of gas bladder not
expanded into horn-like diverticula
(Figs. 3A, 3B)
____________________________________________________
2
1b. Each posterior chamber of gas bladder
expanded into elongate horn-like di-
verticulum (Figs. 3C, 3D; Essequibo and
Amazon basins minus Xingu and To-
cantins basins)
______________
Rhynchodoras woodsi
2a. Midlateral scutes (beginning with infra-
nuchal) 34–36, anterior ones shallow
(depth about one-fifth of corresponding
body depth) with posterior margins of
dorsal and ventral laminae (wings)
lacking conspicuous serrations; all three
tympanal scutes poorly developed and
inconspicuous (Orinoco basin)
_____________
_______________
Rhynchodoras castilloi, new species
2b. Midlateral scutes 33–34, anterior ones
deep (depth about one-third to one-
quarter of corresponding body depth)
with posterior margins of dorsal and
ventral laminae (wings) well serrated;
second and third tympanal scutes well
developed, latter with medial carina
(Xingu and Tocantins basins)
_______________
___________________________________________
Rhynchodoras xingui
MATERIAL EXAMINED
Measurements refer to standard lengths.
Rhynchodoras woodsi: Brazil, Amazonas: ANSP
178547, 1, 33.7 mm, Rio Solimo˜es, 6.2 km
upstream from Santo Antoˆnio do Ic¸a, 35 km
downstream from Gr. Rural Muiraquita˜,
3u089440S, 67u539580W; ANSP 179122, 1,
42.5 mm, Rio Solimo˜es, upstream of Vila de
Careiro, 3u149180S, 59u549210W; ANSP 179123, 1,
34 mm, Rio Solimo˜ es, upriver of Vila de Careiro,
3u149190S, 59u549280W; ANSP 181050, 4, 30.6–
35.6 mm, Rio Amazonas, 4 miles downriver of
Novo Oriente, 30 miles upriver of Itacoatiara,
3u179130S, 58u569010W; ANSP 181051, 1,
BIRINDELLI ET AL.—NEW RHYNCHODORAS 681
37.6 mm, Rio Amazonas, 3 miles downstream of
Novo Oriente, 31 miles upstream from Itacoa-
tiara, 3u169520S, 58u569270W; ANSP 181052, 2,
29–30 mm, Rio Solimo˜es, 9 km upiver from
Santo Antoˆnio do Ic¸ a, 36.8 km downriver from
Gr. Rural Muiraquita˜, 3u089530S, 67u539290W;
ANSP 181053, 12, 26.0–33.7 mm, Rio Solimo˜es,
9.5 km upriver of Santo Antoˆ nio do Ic¸a, 38.1 km
downriver of Gr. Rural Muiraquita˜, 3u089480S,
67u539560W; ANSP 181054, 1, 31 mm, Rio Soli-
mo˜es, above mouth of Rio Negro, upriver of Vila
de Careiro, 3u149S, 59u549W; ANSP 181059, 2,
36.4–38 mm, Rio Purus, Solimo˜ es Dr., 3u419220S,
61u289190W; ANSP 181060, 1, Rio Amazonas,
14 km upriver from Jatuarana, 28.5 km downriv-
er of Manaus, 3u059330S, 59u469150W; ANSP
182853, 1, Rio Solimo˜es, 9.5 km upriver of Santo
Antoˆnio do Ic¸a, 38.1 km downriver of Gr. Rural
Muiraquita˜, 3u089480S, 67u539560W; INPA 15679,
2, Rio Branco, Negro Dr.; INPA uncat., 1, Rio
Branco, Negro Dr., Parana Paracarica, 1u189S,
61u429W; MZUSP 53308, 4, 27.3–41.2 mm, Rio
Amazonas, Parana´ do Serpa, 3u199S, 58u359W;
MZUSP 55819, 1, 35.1 mm, Rio Solimo˜ es, 3u099S,
67u549W; MZUSP 55820, 5, 29–36.3 mm, Rio
Solimo˜es, 3u099S, 67u549W; MZUSP 56173, 1,
38.6 mm, Rio Negro; MZUSP 56177, 1, 30 mm,
Rio Negro, 1u589S, 61u169W; MZUSP 56845, 5,
33.7–49.3 mm, Rio Solimo˜ es, 3u149S, 59u559W;
MZUSP 56848, 2, 23–32.8 mm, Rio Solimo˜es,
3u369S, 61u199W; MZUSP 56853, 7, 21.6–
31.2 mm, Rio Solimo˜es; MZUSP 56856, 11,
24.6–40.3 mm, 1 CS, 26.0 mm, Rio Solimo˜es;
MZUSP 56859, 11, 24.6–29.9 mm, Rio Solimo˜es,
3u359S, 61u079W; MZUSP 56862, 4, 26.6–29 mm,
Rio Amazonas, 3u169S, 58u579W; MZUSP 56872,
20, 24–40 mm, 1 CS, 23.1 mm, Rio Amazonas
near Madeira, 3u209S, 58u369W; MZUSP 56873, 7,
26.4–37.4 mm, Rio Amazonas near Madeira,
3u199S, 58u359W; MZUSP 57238, 10, 29.8–
46.8 mm, Rio Amazonas below mouth of Rio
Madeira, 3u209S, 58u359W; MZUSP 57241, 1,
30.7 mm, Rio Solimo˜ es; MZUSP 57242, 1,
31.8 mm, Rio Solimo˜es, 3u499S, 61u389W; MZUSP
57248, 5, 26.3–32.3 mm, Rio Amazonas below
mouth of Rio Madeira; MZUSP 57251, 1,
41.4 mm, Rio Solimo˜ es; MZUSP 57252, 1,
47.9 mm, Rio Amazonas above Madeira, 3u169S,
58u579W; MZUSP 57260, 1, 32.5 mm, Rio Soli-
mo˜es, 3u369S, 61u219W; MZUSP 57261, 6, 26.3–
33.5 mm, Rio Amazonas above Madeira, 3u169S,
58u579W; MZUSP 57262, 3, 28.5–36.8 mm, Rio
Solimo˜es, 3u149S, 59u549W; MZUSP 57292, 1,
44.4 mm, Rio Amazonas near Madeira, 3u209S,
58u369W; MZUSP 57308, 4, 27.0–39.8 mm, Rio
Solimo˜es, 3u279S, 60u459W; MZUSP 57309, 1,
38.5 mm, Rio Solimo˜es, 3u149S, 59u549W; MZUSP
57310, 1, 35.0 mm, Rio Amazonas above Madei-
ra, 3u169S, 58u569W; MZUSP 57313, 2, 38.5–
45.2 mm, Rio Amazonas near Madeira, 3u209S,
58u359W; MZUSP 57316, 1, 33.7 mm, 1 CS,
44.7 mm, Rio Amazonas below mouth of Rio
Madeira, 3u209S, 58u369W; MZUSP 57319, 1,
51.5 mm, Rio Solimo˜es, 3u279S, 60u459W; MZUSP
57328, 1, 47.9 mm, Rio Solimo˜es, 3u269S,
60u459W; MZUSP 57980, 3, 33.7–40.9 mm, Rio
Amazonas below mouth of Rio Madeira, 3u209S,
58u369W; MZUSP 57983, 4, 30.0–39.8 mm, Rio
Amazonas below mouth of Rio Negro; MZUSP
57985, 2, 32.5–37.6 mm, Rio Amazonas below
mouth of Rio Negro, 3u059S, 59u479W; MZUSP
57986, 3, 31.2–36.7 mm, Rio Amazonas below
mouth of Rio Madeira, 3u209S, 58u369W; MZUSP
57987, 2, 31.7–33.5 mm, Rio Amazonas below
mouth of Rio Negro, 3u059S, 59u469W; MZUSP
57992, 6, 33.4–67 mm, Rio Amazonas below
mouth of Rio Madeira, 3u209S, 58u359W; MZUSP
58011, 1, 48.5 mm, Rio Amazonas below mouth of
Rio Negro, 3u059S, 59u479W; MZUSP 58016, 2,
35.1–38.3 mm, Rio Amazonas below mouth of Rio
Negro, 3u169S, 58u569W; MZUSP 58017, 2, 31.5–
33 mm, Rio Amazonas below mouth of Rio Negro,
3u169S, 58u569W; MZUSP 58248, 2, 24.5–27.7 mm,
Rio Solimo˜es, 3u099S, 67u549W; MZUSP 86810, 1,
52.3 mm, Rio Amazonas above mouth of Rio
Madeira, 3u359S, 59u089W; MZUSP 86811, 2, 33.7–
62.6 mm, Rio Solimo˜es near Purus, 3u369S,
61u209W; MZUSP 86815, 14, 28.8–47.9 mm, 1
CS, 47.6 mm, Rio Amazonas below mouth of Rio
Madeira, 3u209S, 58u369W; MZUSP 86816, 5, 28.5–
37.8 mm, Rio Solimo˜ es below mouth of Rio Purus,
3u279S, 60u459W; Roraima: MZUSP 56174, 1,
30.5 mm, Rio Branco, 1u179S, 61u509W. Ecuador:
FMNH 77008, holotype, 110.4 mm, ´o Bobo-
naza, tributary ´o Pastaza, Maran˜ on Dr., Moreta
Bobonaza, between Sarayacu and Montalvo;
MEPN no catalog number (?ex. FMNH 77009, 1
of 2 paratypes), 108.4 mm, same data as holotype
(Ibarra and Stewart [1987] noted as missing the
two paratypes cited by Glodek [1976:44] as FMNH
77009, 85.2–103.8 mm SL; it seems likely but
remains uncertain whether this MEPN specimen
originated from FMNH 77009). Guyana: ROM
62601, 1, 44.2 mm, Essequibo River at Kurupu-
kari, 4u409S, 58u409W. Peru, Loreto Department:
ANSP 181042, 5, 64.0–84.3 mm, ´o Amazonas,
vicinity of Iquitos; MZUSP 86809, 1, 64.7 mm, ´o
Amazonas, vicinity of Iquitos; UF 131106, 1,
25 mm, Can˜ o Yarina–Rio Pacaya, Ucayali Dr.,
Reserva Nacional Pacaya Samiria, 5u19905.50S,
74u30918.060W.
Rhynchodoras xingui: Brazil: SMF 5281, holo-
type, 63 mm, upper Rio Xingu; SMF 5282,
paratype, 44.5 mm, same data as holotype; Para:
INPA 26540, 2, 62.8–64.2 mm, Rio Tocantins,
Tucuruı´, 3u429S, 49u429W.
682 COPEIA, 2007, NO. 3
ACKNOWLEDGMENTS
The manuscript benefited from the comments
and suggestions of A. Akama, C. Moreira, and L.
Sousa. For loans and exchanges of specimens we
thank: J. Armbruster, R. Barriga, N. Chao, B.
Collette, W. Crampton, E. Holm, F. Krupp, J.
Lundberg, O. Oyakawa, F. Provenzano, L. Rapp
Py-Daniel, M. Rogers, L. Sousa, D. Werneke, and
J. Williams. For field assistance we thank: M.
Arce, A. Bullard, O. Castillo, C. DoNascimiento,
C. Sabaj Pe´rez, and S. Snyder. Special thanks to F.
Krupp for use of photo of holotype of R. xingui
by S. Traenkner, and to M. Rogers for use of
photo of holotype R. woodsi by M. Littmann.
Study conducted in partial fulfillment of Masters
degree by JLOB funded by FAPESP (03/09304-
3). Additional funding for museum visits and
fieldwork in Brazil and Peru provided by the All
Catfish Species Inventory (NSF DEB-0315963).
LITERATURE CITED
ARRATIA, G., AND L. HUAQUIN. 1995. Morphology of
the lateral line system and of the skin of
diplomystid and certain primitive loricarioid cat-
fishes and systematic and ecological considera-
tions. Bonner Zoologische Monographien 36:
1–110.
BRITSKI, H. 1972. Sistema´tica e evoluc¸a˜o dos Auche-
nipteridae e Ageneiosidae (Teleostei, Siluri-
formes). Unpubl. Ph.D. diss., Universidade de
Sa˜o Paulo, Sa˜o Paulo, Brazil.
CARVAJAL, V. A. 2005. Diversidad y dieta de los bagres
de la familia Doradidae de Venezuela. Unpubl.
bachelor diss., Universidad Nacional Experimental
de los Llanos Occidentales ‘‘Ezequiel Zamora,’’
Guanare, Venezuela.
EIGENMANN, C. H. 1925. A review of the Doradidae,
a family of South American Nematognathi, or
catfishes. Transactions of the American Philosoph-
ical Society 22:280–365.
FERRARIS, C. J. 1988. The Auchenipteridae: putative
monophyly and systematics, with a classification of
the neotropical doradoid catfishes (Ostariophysi:
Siluriformes). Unpubl. Ph.D. diss., City University
of New York, New York.
FERRARIS, C. J., AND R. P. VARI. 1999. The South
American catfish genus Auchenipterus Valenciennes,
1840 (Ostariophysi: Siluriformes: Auchenipteri-
dae): monophyly and relationships, with a revision-
ary study. Zoological Journal of the Linnean
Society 126:387–450.
GLODEK, G. S. 1976. Rhynchodoras woodsi, a new catfish
from Eastern Ecuador (Siluriformes: Doradidae)
with a redefinition of Rhynchodoras. Copeia 1976:
43–46.
HIGUCHI, H. 1992. A phylogeny of the South
American thorny catfishes (Osteichthyes; Siluri-
formes, Doradidae). Unpubl. Ph.D. diss., Harvard
University, Cambridge, Massachusetts.
IBARRA, M., AND D. J. STEWART. 1987. Catalogue of type
specimens of Recent fishes in Field Museum of
Natural History. Fieldiana Zoology 35:1–112.
KLAUSEWITZ, W., AND F. RO
¨SSEL. 1961. Rhynchodoras
xingui, ein bemerkenswerter neuer Wels aus
Brasilien (Pisces, Siluroidea, Doradidae). Senck-
enbergiana Biologica 42:45–48.
KNER, R. 1853. Ueber einige Sexual-Unterschiede bei
der Gattung Callichthys und die Schwimmblase bei
Doras C. Val. Sitzungsberichte der Kaiserlichen
Akademie der Wissenschaften, Mathematisch-Nat-
urwissenschaftlichen Classe, Wien 11:138–146.
LEVITON, A. E., R. H. GIBBS,JR., E.HEAL,AND C. E.
DAWSON. 1985. Standards in herpetology and
ichthyology: part I. Standard symbolic codes for
institutional resource collections in herpetology
and ichthyology. Copeia 1985:802–832.
NG,H.H.2004.TheMicrosynodontis (Teleostei:
Siluriformes: Mochockidae) of the lower Guinea
region, west central Africa, with the description of
eight new species. Zootaxa 531:1–52.
NG, H. H. 2005. Pseudolaguvia foveata, a new catfish
(Teleostei: Eresthistidae) from northeast India.
Ichthyological Exploration of Freshwaters 16:183–
191.
RISSO, F. J. J., AND M. I. MORRA. 1964. Parapterodoras
paranensis: nuevo ge´ nero y nueva especies de
Doradidae. Notas del Museo de Ciencias Naturales
del Chaco 1:1–4.
ROBERTS, T. R. 1982. Unculi (horny projections
arising from single cells), an adaptative feature of
the epidermis of Ostariophysian fishes. Zoologica
Scripta 11:55–76.
ROBERTS, T. R. 1989. Systematic resivion and de-
scription of new species of suckermouth catfish
(Chiloglanis, Mochokidae) from Cameroun. Pro-
ceedings of the California Academy of Sciences
46:151–178.
SABAJ, M. H. 2002. Taxonomy of the Neotropical
thorny catfishes (Siluriformes: Doradidae) and
revision of genus Leptodoras. Unpubl. Ph.D. diss.,
University of Illinois, Urbana-Champaign, Illinois.
SABAJ, M. H. 2005. Taxonomic assessment of Leptodoras
(Siluriformes: Doradidae) with descriptions of three
new species. Neotropical Ichthyology 3:637–678.
SOARES-PORTO, L. 1998. Monophyly and relationships
of the Centromochlinae (Siluriformes: Auchenip-
teridae), p. 331–350. In: Phylogeny and Classifica-
tion of Neotropical Fishes. L. R. Malabarba, R. E.
Reis, R. P. Vari, Z. M. S. Lucena, and C. A. S.
Lucena (eds.). EDIPUCRS, Porto Alegre, Brazil.
SOUSA,L.M.,AND L. H RAPP PY-DANIEL.2005.
Description of two new species of Physopyxis and
redescription of P. lyra (Siluriformes: Doradidae).
Neotropical Ichthyology 3:625–636.
TAYLOR, R., AND C. C. VAN DYKE. 1985. Revised
procedures for staining and clearing small fishes
and other vertebrates for bone and cartilage study.
Cybium 9:107–119.
WALLACE, A. R. 2002. Peixes do Rio Negro [Fishes of
the Rio Negro]. Organization, introductory text,
and translation by Moˆnica de Toledo-Piza Ragazzo.
Editoria de Universidade de Sa˜o Paulo, Sa˜o Paulo,
Brazil.
BIRINDELLI ET AL.—NEW RHYNCHODORAS 683
WALSH, S. J. 1990. A systematic revision of the
Neotropical catfish family Ageneiosidae (Teleostei:
Ostariophysi: Siluriformes). Unpubl. Ph.D. diss.,
University of Florida, Gainesville, Florida.
WILEY, M. L., AND B. B. COLLETTE. 1970. Breeding
tubercles and contact organs in fishes: their
occurrence, structure and significance. Bulletin of
the American Museum of Natural History 143:
143–216.
( JLOB) MUSEU DE ZOOLOGIA DA UNIVERSIDADE DE
SA
˜OPAULO,CAIXA POSTAL 42494, CEP 04218-
970, SA
˜OPAULO,BRAZIL; (MHS) DEPARTMENT OF
ICHTHYOLOGY,THE ACADEMY OF NATURAL
SCIENCES, 1900 BENJAMIN FRANKLIN PARKWAY,
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MUSEO DE ZOOLOGI
´A,UNIVERSIDAD NACIONAL
EXPERIMENTAL DE LOS LLANOS OCCIDENTALES
EZEQUIEL ZAMORA,MESA DE CAVACAS,ESTADO
PORTUGUESA,GUANARE 3310, VENEZUELA .E-
mail: ( JLOB) jbirindelli@yahoo.com.br ;
(MHS) sabaj@acnatsci.org; and (DCT) taphorn@
gmail.com. Send reprint requests to MHS.
Submitted: 17 March 2006. Accepted: 26 Dec.
2006. Section editor: J. W. Armbruster.
684 COPEIA, 2007, NO. 3
... Sousa & Rapp Py-Daniel (2005) revisou o gênero Physopyxis, descrevendo duas espécies. Birindelli et al. (2007) descreveram ...
... Auchenipteridae é a única família de Siluriformes na qual os tubérculos podem ser, em alguns casos, chamados nupciais, por estarem relacionados à reprodução (ver caracteres abaixo). Em muitos casos, o tamanho, forma e distribuição dos tubérculos têm implicações taxonômicas e filogenéticas (e.g., Birindelli et al., 2007). ...
... Contudo, em Hypophthalmus e Loricarioidea os bulbos laterais da bexiga natatória são envolvidos pela expansão da parapófise da vértebra complexa e pelos ossos da porção posterior do crânio (Alexander, 1964: 428;Chardon, 1968;Arratia, 1992: #54). Em Agamyxis, Doras phlyzakion, Tocantinsia e Trachycorystes a bexiga natatória apresenta um par de divertículos posteriores digitiformes com constrição basal (Birindelli et al., 2009; (Walsh, 1990;Sabaj, 2002: #5;Akama, 2004;#71;Birindelli, 2006: #23;Birindelli et al., 2007;Birindelli et al., 2009). Em Pterodoras granulosus há um par de divertículos extremamente grandes e ramificados (Birindelli et al., 2009 ...
... Sabaj (2005) revised Leptodoras, describing three species as new. Two years later, Birindelli et al. (2007) described Rhynchodoras castilloi from Higuchi et al. (2007) described a new genus and species, Merodoras nheco; and Sabaj Pérez et al. (2007) described †Doras dionae, the only named fossil species. In 2008, described two new species of Rhinodoras; revised Doras, describing three species as new; described Leptodoras oyakawai; and Piorski et al. (2008) described Platydoras brachylecis and revalidated P. hancockii. ...
... The doradids Agamyxis and Doras phlyzakion, and auchenipterids Tocantinsia and Trachycorystes have a pair of digitiform subterminal diverticula (Fig. 14a-d;Birindelli et al., 2009;. The Doradids Leptodoras (except L. marki and L. oyakawai) and Rhynchodoras woodsi, and auchenipterid Ageneiosus (except A. pardalis and A. ucayalensis) have a pair of hornlike subterminal diverticula (Fig. 11;Walsh, 1990;Sabaj, 2002: #5;Akama, 2004: #71;Birindelli et al., 2007;Birindelli et al., 2009;. The doradid Pterodoras granulosus has a pair of extremely well developed and branched subterminal diverticula ( Fig. 14e; Birindelli et al., 2009;Sousa, 2010: #97). ...
... The number of midlateral scutes in doradids was conventionally established as beginning with the infranuchal scute, and is useful in species diagnosis (Sabaj, 2005;Birindelli et al., 2007). The number of midlateral scutes may vary significantly among species of a single genus (e.g., Oxydoras), but it is quite conservative within a single species. ...
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... Several Tertiary fossils belonging to typically lowland Amazonian taxa are present in regions currently lacking any Amazonian connection, such as Magdalena and Caribbean coastal rivers from the northern coast of Venezuela: Arapaima, Brachyplatystoma, Colossoma, Doras, Hydrolycus, and Phractocephalus (G. Ballen, personal communication;Lundberg et al., 1986Lundberg et al., , 1988Lundberg et al., , 2010Lundberg, 1997Lundberg, , 2005Sabaj Pérez et al., 2007). This demonstrates that such regions were in the past also part of some other distributional patterns described herein. ...
... Examples of this pattern here recognized are: Acnodon normani, Aspidoras poecilus (see Nijssen and Isbrücker, 1976), Astyanax argyrimarginatus, Bivibranchia velox (see Langeani, 1996), Centro mochlus simplex, Creagrutus britskii (see Meza-Vargas, 2015), Creagrutus mucipu (see Meza-Vargas, 2015), Hemiancistrus spilomma, Hemiodus tocanti nensis, Hyphessobrycon loweae (see Ingenito et al., 2013), Hypostomus faveolus (see Zawadzki et al., 2008), Laemolyta fernandezi, Melanocharacidium auroradiatum, Mesonauta acora (see Kullander and Silfvergrip, 1991), Moenkhausia loweae (see Marinho, 2009), Moenkhausia pyrophthalma, Rhyn chodoras xingui (see Birindelli et al., 2007), Semaprochilodus brama (see Castro and Vari, 2004), Sternopygus xingu, and Tometes ancylorhyn chus (see Andrade et al., 2016). ...
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We provide a general compilation of the diversity and geographical distribution of Amazonian fishes, updated to the end of 2018. Our database includes documented distributions of 4214 species (both Amazonian and from surrounding basins), compiled from published information plus original data from ichthyological collections. Our results show that the Amazon basin comprises the most diverse regional assemblage of freshwater fishes in the world, with 2716 valid species (1696 of which are endemic) representing 529 genera, 60 families, and 18 orders. These data permit a view of the diversity and distribution of Amazonian fishes on a basinwide scale, which in turn allows the identification of congruent biogeographical patterns, here defined as the overlapping distributions of two or more lineages (species or monophyletic groups). We recognize 20 distinct distributional patterns of Amazonian fishes, which are herein individually delimited, named, and diagnosed. Not all these patterns are associated with identifiable geographical barriers, and some may result from ecological constraints. All the major Amazonian subdrainages fit into more than one biogeographical pattern. This fact reveals the complex history of hydrographical basins and shows that modern basin-defined units contribute relatively little as explanatory factors for the present distributions of Amazonian fishes. An understanding of geomorphological processes and associated paleographic landscape changes provides a far better background for interpreting observed patterns. Our results are expected to provide a framework for future studies on the diversification and historical biogeography of the Amazonian aquatic biota.
... Whereas most species of Doradidae have a single-pored axillary gland, others possess a glandular tissue associated with (Birindelli et al. 2007), Doras (Sabaj Pérez and Birindelli 2008), Anduzedoras, Hassar (Birindelli et al. 2011), Nemadoras (Sabaj Pérez et al. 2014), Tenellus, Trachydoras, and the basal species of Leptodoras (Sabaj 2005). Nothing is known about the function and anatomical characteristics of the epidermal glands present in these species, how their structure is compared to that described here for Acanthodoras, or to that described for other singled-pored doradids (e.g., Lithodoras dorsalis). ...
Article
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Acanthodoras is the only genus of catfish known to secrete a conspicuous and abundant milky-looking substance through an axillary pore located just below the base of the posterior cleithral process. Despite this remarkable feature, there is no published information on the anatomical structures that produce the secretion and its possible biological/ecological functions. Dissection and histological analysis of preserved specimens of A. spinosissimus revealed the presence of a saccular axillary gland with large, binuclear secretory cells, similar to those found in other poisonous catfish. Secretory cells near the lumen appear to lose nuclei and become filled with secretory products, possibly with proteinaceous elements, as indicated by their eosinophilic appearance. As far as we know, the saccular morphology of the gland appears to constitute a unique characteristic of Acanthodoras among Doradidae catfishes. Further studies are necessary to determine the chemical composition of the secretion, as well as its possible uses by the catfish in its natural environment.
... sido intensamente melhorada por diversos trabalhos de descrições de espécies ( Birindelli et al., 2007;Higuchi et al., 2007;Sabaj Pérez et al., 2007;Birindelli et al., 2008;Piorski et al., 2008;Birindelli & Sousa, 2010) e revisões taxonômicas de gêneros ( Sabaj, 2005;Sousa & Rapp Py-Daniel, 2005;Sousa & Birindelli, 2011;Birindelli & Sabaj Pérez, 2011). Apesar disso, ainda existem algumas espécies esperando uma descrição formal, como, por exemplo, Nemadoras sp. ...
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The Neotropical catfishes of the genus Auchenipterus Valenciennes (1840) are reviewed. The genus is hypothesized to be a monophyletic assemblage on the basis of the shared presence of grooves in the ventral surface of the head that accommodate adducted mental barbels. A possible second synapomorphy, the presence of papillae on the dorsal and medial surface of the ossified maxillary barbel of mature males, is tentatively advanced pending discovery of adult males of three species. Contrary to previous hypotheses which considered Auchenipterus to consist of a maximum of five species, we recognize 11 species, including two previously undescribed forms, A. britskii and A. menezesi: Auchenipterus is broadly distributed through the Rio Orinoco, Rio Amazonas, and Rio de La Plata basins, and the coastal drainages of the Guianas, with one species in the Rio Pindare-Mirim and Rio Parnaiba basins of northeastern Brazil. Auchenipterus nuchalis, previously thought to be broadly distributed across the range of the genus, is found to rather have a restricted distribution in the eastern portions of the Amazon basin, the lower portions of the Rio Tocantins, and lower courses of some rivers in Suriname and French Guiana. Citations of A. nuchalis from elsewhere in the range of the genus are of other species. Euanemus Müller & Troschel (1842) and Ceratocheilus Miranda Ribeiro (1918) are considered synonyms of Auchenipterus. Euanemus colymbetes Müller & Troschel (1842) is considered a synonym of Auchenipterus (fen/ata Valenciennes (1840), and A. paysanduanus Devincenzi (1933) is placed into the synonymy of A. nigripinnis Boulenger (1895). A neotype is designated for Hypopthalmus nuchalis Spix & Agassiz (1829). Lectotypes are designated for Euanemus colymbetes and Auchenipterus nigripinnis.
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A second species of Rhynchodoras is described from eastern Ecuador. This new species was collected from the Rio Bobonaza of the upper Amazon drainage in eastern Ecuador, over 2735 km west of the type locality of Rhynchodoras xingui, the only other known member of the genus. A comparison is made with R. xingui from the Rio Xingu of eastern-central Brazil, along with a redefinition of the limits of the genus Rhynchodoras.