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Micromyzon akamai, Gen. et Sp. Nov., a Small and Eyeless Banjo Catfish (Siluriformes: Aspredinidae) from the River Channels of the Lower Amazon Basin

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A new genus and species of aspredinid catfish, Micromyzon akamai, is described from trawl collections made in river channels of the Brazilian Amazon. This taxon is uniquely diagnosed by several apomorphies including lack of eyes, reduced melanic pigmentation, extremely reduced premaxillae and hypertrophied development of skull roofing elements and body armor. Its sister-group relationship to a clade containing Dupouyichthys and Ernstichthys is supported by the lack of lower jaw dentition, well-developed dorsal armor plates, and an anterior shift in the origin of the anal fin. /// Micromyzon akamai, novo gênero e nova espécie de Aspredinidae, é descrito procedente de coletas de arrasto de fundo nas calhas dos rios da Amazônia brasileira. Este taxon é diagnosticado por várias apomorfias exclusivas, incluindo a ausência de olhos, redução da pigmentação melânica, extrema redução dos prémaxilares e desenvolvimento hipertrofiado dos elementos da base do crânio e da armadura óssea. Possui como grupo mais próximo o clado contendo Dupouyichthys e Ernstichthys, com o qual compartilha a ausência de dentição da mandíbula inferior, placas ósseas dorsais muito desenvolvidas e o deslocamento da origem da nadadeira anal para uma posição mais anterior.
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Copeia, 1996(3), pp. 641-648
Micromyzon
akamai, Gen. et Sp. Nov., a Small and Eyeless Banjo
Catfish (Siluriformes: Aspredinidae) from the River Channels
of the Lower Amazon Basin
JOHN P. FRIEL AND JOHN G. LUNDBERG
A new genus and species of aspredinid catfish, Micromyzon akamai, is described
from trawl collections made in river channels of the Brazilian Amazon. This
taxon is uniquely diagnosed by several apomorphies including lack of eyes,
reduced melanic pigmentation, extremely reduced premaxillae and hypertro-
phied development of skull roofing elements and body armor. Its sister-group
relationship to a clade containing Dupouyichthys and Ernstichthys is supported
by the lack of lower jaw dentition, well-developed dorsal armor plates, and an
anterior shift in the origin of the anal fin.
Micromyzon akamai, novo genero e nova especie de Aspredinidae, e descrito
procedente de coletas de arrasto de fundo nas calhas dos rios da Amazonia
brasileira. Este taxon e diagnosticado por varias apomorfias exclusivas, incluindo
a ausencia de olhos, reduiao da pigmentaiao melanica, extrema reduco dos pre-
maxilares e desenvolvimento hipertrofiado dos elementos da base do cranio e
da armadura 6ssea. Possui como grupo mais pr6ximo o clado contendo Dupouy-
ichthys e Ernstichthys, com o qual compartilha a ausencia de denti0ao da man-
dibula inferior, placas osseas dorsais muito desenvolvidas e o deslocamento da
origem da nadadeira anal para uma posiaio mais anterior.
ERNANDEZ-YEPEZ (1953) first recog-
nized a small clade of aspredinid catfishes,
now known as the tribe Hoplomyzontini (My-
ers, 1960), for the genera Hoplomyzon,
Dupouy-
ichthys,
and Ernstichthys.
More recently, Stewart
(1985), Taphorn and Marrero (1990), and Friel
(1994) have further documented monophyly of
the Hoplomyzontini with numerous unique
morphological characters, including an unusual
body armor formed by dorsal and ventral ver-
tebral processes and expanded lateral-line os-
sicles. Hoplomyzontines are phenotypically dis-
tinctive catfishes of small body size (the largest,
Ernstichthys
intonsus, attain only approximately
50 mm SL). The majority of hoplomyzontine
species have distributions in the western Ama-
zon, western Orinoco, Maracaibo, and Mag-
dalena basins. Until now, there were only two
records of this group from the big lowland riv-
ers of eastern South America, one in the lower
Orinoco (Baskin, Lundberg, and Mago-Leccia
paper, without published abstract, read at 1979
meeting of the American Society of Ichthyol-
ogists and Herpetologists, Orono, Maine) and
another from the lower Tapajos (Friel, 1994).
The species described here is the first hoplo-
myzontine known from the lower Amazon and
Tocantins rivers.
The new aspredinid was collected with bot-
tom trawls during the 1994 expedition of a US-
Brazilian collaborative project ("Calhamazon")
that is surveying the fishes of the major channels
of the Amazon River and its larger tributaries
in Brazil. Catfishes dominate the Amazon River
channel fauna, accounting for more than half
of over 240 species collected by the project to
date. Many of the catfishes living in the channels
of South American rivers are highly specialized.
Lundberg and Rapp Py-Daniel (1994) described
Bathycetopsis
oliveirai,
a small cetopsid catfish with
no eyes and greatly reduced pigment but with
hypertrophied olfactory organs. Similarly, the
aspredinid catfish treated here lacks eyes and is
reduced in size and pigmentation (Fig. 1), but
it exhibits extreme hypermorphic characteris-
tics of its skeleton. In this paper, we describe
the new taxon and discuss its relationships with-
in the Hoplomyzontini.
MATERIALS AND METHODS
Skeletal characters of the new catfish and re-
lated taxa were examined on cleared-and-stained
specimens or radiographs. Anatomical illustra-
tions were done using a camera lucida attached
to a Wild M-8 microscope. Osteological termi-
nology generally follows Lundberg (1975, 1982)
and Royero (1987).
Measurements were made to the nearest 0.1
mm from scaled distances between magnified
landmark points recorded on paper using a Wild
M-8 microscope equipped with a camera lucida.
? 1996 by the American Society of Ichthyologists and Herpetologists
COPEIA, 1996, NO. 3
Fig. 1. Micromyzon
akamai,
Holotype MZUSP
48550, 13.6 mm SL from Rio Tocantins, Brazil;
(A) dorsal
view;
(B) lateral view; (C) ventral view.
In this procedure, specimens are sequentially
oriented in dorsal, ventral, and lateral view on
moistened cheesecloth so that their target land-
mark points are in the same focal plane. Re-
peated measurements on the same individual
yielded measurement error estimates of less than
4%. This was less than error estimates for re-
peated measurements made directly with cali-
pers in this study. Fish lengths are given as stan-
dard length (SL). Caudal peduncle depth is its
minimum depth. All lepidotrichs are included
in the fin-ray counts. Total vertebral counts in-
clude the five fused vertebrae in the Weberian
complex and the compound caudal vertebra
which is counted as one. Institutional abbrevi-
ations follow Leviton et al. (1985).
Micromyzon
n. gen.
Figures 1-5, Table 1
Type species.-Micromyzon akamai sp. nov.
Diagnosis.-A miniature hoplomyzontine as-
predinid (maximum observed SL less than 16
642
FRIEL AND LUNDBERG-NEW DEEP WATER ASPREDINID
PTr-
(
SC
V5tp-
soc
I I
Fig. 2. Dorsal view of neurocranium and Weber-
ian complex of Micromyzon
akamai,
Paratype
USNM
337566; ACF = anterior cranial fontanel, FRT =
frontal, LET = lateral
ethmoid, MET = mesethmoid,
PTO = pterotic, SCL = supracleithrum,
SOC = su-
praoccipital,
SPO = sphenotic,
V4tp = transverse
pro-
cess of vertebra
4, V5tp = transverse
process of ver-
tebra 5. Scale bar = 1 mm.
mm) distinguished by the following apomor-
phies: eyes absent (Fig. 1A-B); anterior cranial
fontanel highly reduced and posterior cranial
fontanel absent (Fig. 2); paired foramina bor-
dered by supracleithra, supraoccipital and We-
berian complex highly reduced or absent (Fig.
2); premaxillae extremely reduced; limb of pal-
atine posterior to lateral ethmoid articulation
much shorter than anterior limb; lateral-line
ossicles hypertrophied to form an armor of
overlapping crescentic plates with dorsal and
ventral limbs tilted anteriorly (Fig. 3); absence
of rows of large tubercles along lateral line and
posterior portion of body; postcleithral pro-
cesses short, rounded; posterior coracoid pro-
cesses very short, not extending past anterior
limit of basipterygia; typical banding pattern of
other hoplomyzontines reduced (Fig. 1
A-B). See
description and discussion for contrasting char-
acter states and comparisons with other hoplo-
myzontines.
Fig. 3. Right side, lateral view of lateral-line
os-
sicles of Micromyzon
akamai,
Paratype
USNM 337566.
Scale bar = 1 mm.
Etymology.-The name is a combination of mi-
cro, referring to small size, and myzon,
meaning
sucker which is the suffix of Hoplomyzon,
the type
genus of the tribe Hoplomyzontini. Gender
masculine.
Micromyzon
akamai, sp. nov.
Holotype.-MZUSP 48550, 13.6 mm, Brazil,
Para State, Rio Tocantins, above confluence
with Rio Para, 02'02'S, 49'17'W, collected 20
Nov. 1994, with 3 x 1 m bottom trawl at 10-
14 m depth by A. Akama,J. Lundberg, R. Pinto
Ribeiro, F. Langeani, L. Rapp Py-Daniel, A.
Zanata.
Paratypes.-All specimens from Brazil, Para
State. Rio Amazonas: MZUSP 48552, 1 spec.
(cleared and stained), 13.0 mm, 4 Nov. 1994,
south side of river, across from Monte Alegre,
approximately 115 km down river from mouth
of Rio Tapajos, 02?04'S, 53'59'W, collected with
3 x 1 m bottom trawl at 9 m depth by A. Akama,
A. Zanata. FMNH 105106, 2 spec., 14.1-15.3
mm, 5 Nov. 1994, south side of river, across
from Monte Alegre, approximately 115 km
down river from mouth of Rio Tapajos, 02?05'S,
54?00'W, collected with 3 x 1 m bottom trawl
at 8-12 m depth by A. Akama, A. Zanata. MCP
18169, 1 spec., 14.3 mm, 6 Nov. 1994, south
side of river, across from Monte Alegre, ap-
proximately 115 km down river from mouth of
Rio Tapajos, 02005'S, 54?00'W, collected with
3 x 1 m bottom trawl at 5-12 m depth by A.
Akama, J. Lundberg, F. Langeani, L. Rapp Py-
Daniel, R. Pinto Ribeiro, A. Zanata. Rio To-
cantins: USNM 337566, 5 spec. (1 cleared and
stained), 11.0-15.7 mm, 20 Nov. 1994, above
confluence with Rio Para, 02002'S, 49?17'W,
643
COPEIA, 1996, NO. 3
TABLE 1. MEASUREMENT DATA FOR
Micromyzon
akamai,
SL IN
mm, OTHER
LENGTHS
EXPRESSED
IN
THOUSANDTHS
OF SL.
Character Holotype Range Mean n
Standard length (SL) 13.6 11.0-15.8 13.9 15
Predorsal length 434 385-489 427 11
Prepectoral length 243 234-281 255 11
Prepelvic length 368 340-373 355 10
Preanal length 551 490-551 523 11
Pectoral-spine
length 191 120-200 177 11
Dorsal-spine length 169 121-191 158 11
Pelvic-fin length 184 170-191 179 9
Anal-fin
base length 184 161-222 192 11
Caudal-fin length 272 182-272 231 10
Caudal-peduncle length 265 252-322 281 11
Caudal-peduncle
depth 42 34-50 44 10
Depth at dorsal-fin
origin 147 118-156 137 11
Maximum depth of head 176 131-176 147 11
Body width at pectoral
spine insertion 316 281-345 306 11
collected with 3 x 1 m bottom trawl at 9-12 m
depth by A. Akama, R. Pinto Ribeiro, A. Zan-
ata. MZUSP 48551,2 spec., 14.3-15.8 mm, col-
lected with the holotype.
Additional specimens.-All specimens from Bra-
zil, Para State. Rio Amazonas: UAZ 95-151-1,
1 spec., 14.3 mm, 4 Nov. 1994, south side of
river, across from Monte Alegre, approximate-
ly 115 km down river from mouth of Rio Ta-
pajos, 02'04'S, 53'59'W, collected with 3 x 1
m bottom trawl at 8-10 m depth by A. Akama,
A. Zanata. UAZ 95-152-1, 1 spec., 13.8 mm, 4
Nov. 1994, south side of river, across from
Monte Alegre, approximately 115 km down riv-
er from mouth of Rio Tapajos, 02'06'S,
54'00'W, collected with 3 x 1 m bottom trawl
at 15-20 m depth by A. Akama, A. Zanata. Rio
Tocantins: UAZ 95-153-1, 1 spec., 13.5 mm,
20 Nov. 1994, above confluence with Rio Para,
02002'S, 49017'W, collected with 3 x 1 m bot-
tom trawl at 18 m depth by A. Akama, R. Pinto
Ribeiro, A. Zanata.
Diagnosis.-Same as genus.
Description.-Dorsal, lateral, and ventral views
in Figure 1A-C illustrate the general body shape
and pigmentation. Morphometric measure-
ments for holotype and paratypes are summa-
rized in Table 1.
Head depressed, convex in dorsal profile, flat
in ventral profile. Skull ornamentation reduced
relative to other hoplomyzontines; three dor-
somedian bony knobs (supraoccipital, dorsal
lamina of Weberian apparatus and middle nu-
chal plate; Fig. 1B). Both snout and underlying
mesethmoid with a slight notch (Fig. 1A). An-
terior cranial fontanel reduced to a small open-
ing between mesethmoid and margins of fron-
tals, frontals mostly in contact on midline, pos-
terior cranial fontanel absent (Fig. 2). Paired
foramina bordered by supracleithra, supraoc-
cipital and Weberian complex highly reduced
or absent due to broad contact between We-
berian complex and neurocranium (Fig. 2). An-
terior lateral-line ossicles fused to transverse
processes of vertebra 4 (Fig. 2). Transverse pro-
cesses of vertebra 5 slender and project slightly
posteriorly (Fig. 2). Eyes absent (Fig. 1A-B).
Body armored with three series of bony plates.
Dorsal and ventral armor with concave surfaces,
bordered by lateral ridges, lateral armor with
convex surface and lateral ridge. Dorsal series
of bony plates consists of the middle and pos-
terior nuchal plates followed by plates derived
from the expanded tips of vertebral processes
(Fig. 4A). Posterior nuchal plate supported by
processes of vertebra 8; dorsal plates present on
vertebra 9 to compound ural vertebra. The most
anterior plates derived from vertebrae contact
one another.
Ventral series of bony plates begins imme-
diately posterior to the urogenital pore. Typi-
cally two (occasionally three) unpaired plates
derived from vertebral processes precede an
unpaired plate derived from the first anal-fin
pterygiophore; all other plates derived from
vertebral processes, ventral plates present on
vertebra 9 (occasionally 8) to last vertebra be-
644
FRIEL AND LUNDBERG-NEW DEEP WATER ASPREDINID
fore compound ural vertebra; first anal-fin ray
directly posterior to bony plates of vertebra 12
(Fig. 4B).
Lateral armor formed by hypertrophied lat-
eral-line ossicles. Free ossicles begin posterior
to the transverse processes of vertebra 4. First
three ossicles simple, followed by 38-44 en-
larged ossicles which form crescentic plates with
dorsal and ventral portions bending anteriorly
(Fig. 3). No bony knobs present on any ossicles
as in other hoplomyzontines, instead each os-
sicle bears a posteriorly pointed process which
overlaps the next ossicle forming a serrated ridge
along the lateral line. Expanded ossicles contact
the dorsal armor for most of the lateral line
forming the most complete body armor of other
hoplomyzontines. In other hoplomyzontines, the
ossicles only contact the dorsal plates along the
caudal peduncle. Alternating pattern of large
and small ossicles only at anterior end of lateral
line. In all other hoplomyzontines, this alter-
nating pattern is expressed throughout the
length of the lateral line. Total vertebral counts:
modally 30; range 28-32; ribs absent.
Small unculiferous tubercles widely scattered
on body. No longitudinal rows of unculiferous
tubercles appear along lateral line and the pos-
terior portion of the body as in other Aspre-
dinidae.
Anterior nares tubular, each with a low pa-
pilla on its anteroventral margin; posterior nos-
trils with low raised rims. Lower jaw much
shorter than upper, mandibles closing behind
premaxillae, mouth opening anteriorly. Jaw
bones weak and edentulous; premaxillae re-
duced to small nodules articulated to meseth-
moid cornua with no contact on midline, easily
overlooked even in cleared-and-stained speci-
mens; mandibular symphysis without bony ar-
ticulation. Lips smooth, except for a pair of
upper-lip papillae each near rictus and base of
maxillary barbel. All barbels simple without ac-
cessory branches. Maxillary barbels doubly ad-
nate each from its proximoventral surface to
rictus and proximal half of its posterior surface
to side of snout ventral to olfactory organ. Skin
folds form a deep pocket lateral to rictus and
anterior to coronoid process of mandible. Men-
tal barbels inserted at level of hyoid bar; lateral
pair slightly longer than medial pair. Ventral
surface of head in some specimens with small
papillae. Branchiostegal membranes broadly
united to each other and to isthmus, with four
branchiostegal rays. Gill openings ventral, re-
duced to small transverse slits anteromedial to
insertions of pectoral spines.
Two rows of about five gillrakers present on
branchial arches 1-3. Upper pharyngeal tooth
V12pt/ K-
DR2
A' B
Fig. 4. Body armor ofMicromyzon
akamai, (A) dor-
sal body armor of Paratype
USNM 337566; (B) ven-
tral body armor of Paratype
MZUSP
48552; MNP =
middle nuchal plate, PNP = posterior nuchal plate,
DR2 = dorsal spine, V9p-V13p = plates formed by
vertebrae
9-13, AFP = anal-fin
pterygiophore,
AR1
= first anal-fin ray. Scale bar = 1 mm.
plates with 6-7 rows of teeth; each lower pha-
ryngeal tooth plate with single row of teeth along
medial edge. First and third basibranchials ab-
sent, all hypobranchials absent, first and second
pharyngobranchials absent, third ossified, and
fourth cartilaginous.
Dorsal-fin adnate posteriorly; dorsal spinelet
absent, dorsal spine flexible without serrations;
modally four dorsal rays, (range 3-4). Anterior
nuchal plate absent; middle nuchal plate pen-
tagonal with an anterior process; posterior nu-
chal plate laterally expanded, forming anterior
limit of dorsolateral armor-plate series (Fig. 4).
Adipose fin absent; anal fin not adnate with body,
modally eight anal-fin rays (range 7-9).
Caudal fin with elongate lower rays; five up-
per and four lower principal caudal rays, no
upper procurrent caudal rays, 1-2 lower pro-
current rays. Pectoral spine strongly curved, 12-
20% of standard length, no anterior serrations,
modally four posterior serrations (range 3-6).
Modally five pectoral-fin rays (range 4-5). Po-
stcleithral processes short and rounded; axillary
pore present; posterior coracoid processes short,
not reaching anterior limit of basipterygia. Pel-
vic fin with six rays. Basipterygia with raised,
ornamented posterior and anterolateral exten-
sions.
Color.-Pigment greatly reduced in life and al-
cohol, but most specimens exhibiting five dif-
fuse bands (at level of pectoral-fin insertions, at
level of dorsal fin, two bands along posterior
part of body, and a band or dark spot at base
645
COPEIA, 1996, NO. 3
Fig. 5. Distribution of Micromyzon
akamai.
Type
locality
designated by the diamond symbol.
of caudal fin). Areas between bands without pig-
ment. Many specimens also have a dusky area
surrounding the nasal capsules. Ventrally, be-
tween pectoral and pelvic fins, the peritoneum
exhibits
a triangular
or mushroom-shaped
patch
of sparse but large melanophores (Fig. 1C).
Size
and maturity.-Specimens range in size from
11-15.8 mm, and coincidentally
these extreme
individuals are females with mature
eggs. These
represent the smallest sexually mature aspre-
dinids known.
Etymology.-Specific name, akamai, patronymic
in honor of Alberto Akama for his enthusiastic
help in collecting the type series.
Distribution.-All known localities for the new
species are concentrated in two areas (Fig. 5):
Rio Amazonas approximately 115 km below the
mouth of Rio Tapajos near the town of Monte
Alegre, and lower Rio Tocantins about 30 km
above confluence with Rio Para. Because col-
lecting effort was generally comparable in sev-
eral other proximate areas in the lower Amazon
Basin, it appears that M. akamai may have a
patchy distribution.
Habitat.-All specimens taken with benthic
trawls (3 x 1 m try-net trawl nets equipped with
quarter-inch mesh and plastic fly-screen liners).
Present in samples 100-700 m from shore and
at depths from about 5-20 m in channels of the
white-water
rivers on sandy
substrates. Current
speeds in the open channels of the Amazon and
its large tributaries
can reach approximately
1-
1.5 m/sec, but flow rates adjacent
to substrates
would be less. No specimens
have been collected
along beaches, in small streams, or other mar-
ginal habitats. Commonly co-occurring fishes
include gymnotiforms (Apteronotus,
Sternarchel-
la, Sternarchorhamphus,
Sternarchogiton, Eigen-
mannia, Steatogenys,
and Gymnorhamphichthys),
and catfishes (Aspredo,
Leptodoras,
and Pimelo-
dus).
DISCUSSION
This new taxon is the second known ano-
phthalmic hoplomyzontine collected from the
deep river channels of South America.
The first
was a single 15-mm specimen collected with a
bottom trawl at 11-18 m in the lower Orinoco
near Ciudad
Guayana
(Baskin
et al., paper,
with-
out published
abstract,
read at 1979 meeting of
the American Society of Ichthyologists and
Herpetologists, Orono, ME). This Venezuelan
specimen was completely unpigmented unlike
M. akamai which still retains some melano-
phores. Unfortunately this specimen is mis-
placed, and its affinities to other hoplomyzon-
tines remain unknown.
Although the majority
of miniature fishes dis-
play paedomorphic
features including reduced
skeletons, hypermorphic
characters are known
from other miniature catfishes such as scolo-
placids (Schaefer, et al., 1989) and the aspre-
dinid
Acanthobunocephalus
nicoi
(Friel, 1995). Al-
though not closely related to M. akamai,
A. nicoi
also displays
hypertrophied
development of the
supraoccipital
and loss of the posterior cranial
fontanel. The reduction of fontanels in M. ak-
amai would strengthen the cranium and com-
plement the well-developed
body armor of this
new taxon.
Some form of body armor has
evolved at least
six times within the order Siluriformes: one or
more times within Neotropical loricarioid cat-
fishes,
once in the Asian sisorid
Sisor,
once with-
in the subfamily
Doumeinae of the African Am-
philiidae, twice in the neotropical Doradidae,
and once in the tribe Hoplomyzontini of the
neotropical Aspredinidae. These body armors
are of three general types (dermal plates, ver-
tebral processes, and lateral-line
ossicles). The
entire body armor of loricarioids and dorsal ar-
mor of Sisor consists
of one or more rows
of free
dermal plates within the skin. Similar free der-
mal plates also develop in large specimens of
the doradid Lithodoras
(Higuchi, 1992). These
plates may be supported
by vertebral
processes
in some loricarioids such as scoloplacids
(Schae-
fer, 1990) and in Sisor
(Mahajan,
1967), but the
processes never fuse to the plates nor do they
form any of the exposed armor. In contrast,
the
dorsal and ventral body armors of amphiliids,
and hoplomyzontines
are formed solely by ver-
tebral processes
which are expanded distally
to
646
FRIEL AND LUNDBERG-NEW DEEP WATER ASPREDINID
form superficial plates. Finally, the lateral ar-
mor of doradids, Sisor, and hoplomyzontines
consists of hypertrophied lateral-line ossicles
with dorsal and ventral lamina.
The hoplomyzontines are unique among cat-
fishes in having body armor formed of both
vertebral processes and lateral-line ossicles. The
hypertrophied ossicles often contact both the
dorsal and ventral plates to form a complete
armor around the posterior portion of the fish.
This is best developed in M. akamai. The func-
tion of body armor in hoplomyzontines is un-
clear, but Taphorn and Marrero (1990) spec-
ulate that it prevents these fishes from being
crushed by shifting substrate.
Variation in the ventral armor plates is often
used to distinguish different genera of hoplo-
myzontines. These "pre-anal-fin" plates include
the first anal-fin pterygiophore plus the ex-
panded vertebral processes that lie lateral and
anterior to it. We find considerable variation in
the size, shape, and number of these plates with-
in any one hoplomyzontine species. Based on
observations of cleared-and-stained specimens
of all genera, we suggest a more appropriate
way to describe the differences between genera
is to refer to the position of the first anal-fin
ray along the vertebral column. In Hoplomyzon,
which has the largest number of "pre-anal-fin"
plates of any hoplomyzontines, the first anal-ray
articulates with its pterygiophore immediately
posterior to the plates projecting from vertebra
13. In Dupouyichthys,
Ernstichthys,
and Micromy-
zon, the anal fin is shifted anteriorly such that
the first ray originates posterior to the plates of
vertebrae 12. This anal-fin position is the most
anterior of any aspredinid, and we hypothesize
that it is a derived state within hoplomyzontines.
In addition to the anal-fin position, a clade
containing Micromyzon,
Dupouyichthys,
and Ern-
stichthys
is further supported by two other apo-
morphies. All three genera lack teeth on their
dentaries and have more elaborate dorsal and
ventral body armor. In Hoplomyzon,
the verte-
bral plates are relatively small, and plates on
adjacent vertebrae only contact each other at
the very posterior portion of the caudal pedun-
cle. In Micromyzon, Dupouyichthys, and Ernsti-
chthys,
these plates are enlarged and contact or
overlap one another from the dorsal fin to the
caudal fin.
The relationship among the three genera in
this clade can be further resolved since Micro-
myzon
lacks two apomorphies shared by the oth-
er genera. Both Dupouyichthys
and Ernstichthys
have elongate pectoral spines which are greater
than 25% of standard length (Stewart, 1985)
and have the distal tips of the transverse pro-
cesses of vertebra 5 expanded. In contrast, Mi-
cromyzon
has relatively shorter pectoral spines,
less than 20% of standard length, and the distal
tips of the transverse processes of vertebra 5
are not expanded (Fig. 2). Thus, the phyloge-
netic relationships of the four genera in the
tribe Hoplomyzontini are fully resolved as (Hop-
lomyzon (Micromyzon (Dupouyichthys, Ernstich-
thys))).
ADDITIONAL MATERIAL EXAMINED
Dupouyichthys
sapito MCNG 25015 (1 cleared
and stained, 7 alcohol preserved) Venezuela;
USNM 121073 (paratype, 1 cleared and stained)
Venezuela; Ernstichthys
anduzei MCNG 2762 (1
cleared and stained, 1 alcohol preserved) Ven-
ezuela; Ernstichthys megistis UAZ 95-150-1 (1
cleared and stained, 2 alcohol preserved) Ec-
uador; Ernstichthys
intonsus FMNH 94603 (ho-
lotype, radiograph and alcohol preserved) Ec-
uador; Hoplomyzon atrizona MCNG 24796 (1
cleared and stained, 4 alcohol preserved) Ven-
ezuela; Hoplomyzon
papillatus FMNH 94908 (ho-
lotype, radiograph and alcohol preserved) Ec-
uador; Hoplomyzon
sexpapilostoma
MCNG 28919
(6 alcohol preserved) Venezuela; UF 47525
(paratypes, 1 cleared and stained, 4 alcohol pre-
served) Venezuela.
ACKNOWLEDGMENTS
For loans of comparative specimens, we thank
G. Burgess, B. Chernoff, S. Jewett, D. Stewart,
and D. Taphorn. For translation of the abstract
to Portuguese, we thank L. Rapp-Py Daniel.
This material is based upon work supported by
the National Science Foundation and by the
Office of Forestry, Environment and Natural
Resources, Bureau of Science and Technology,
of the US Agency for International Develop-
ment under NSF Grant Number DEB-9300151.
Permission for non-Brazilian participants in this
project to conduct research and collecting in
Brazil was granted by the Conselho Nacional
de Desenvolvimento Cientifico e Tecnologico
(Brazilian National Research Council, CNPq).
Additional support for fieldwork in Brazil came
from grants from the Charles A. Lindbergh
Fund and Harry Frank Guggenheim Founda-
tion, National Science Foundation (INT-
9213839), Duke University Research Council,
Mellon Foundation Grant to the Duke Univer-
sity-University of North Carolina Latin Amer-
ican Studies Program. Radiographic and mi-
croscopic equipment used in the preparation of
this manuscript was provided by the Duke Uni-
versity Morphometric Laboratory for Biologi-
647
COPEIA, 1996, NO. 3
cal Sciences supported by the National Science
Foundation (DIR-9014289).
LITERATURE
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, AND L. RAPP PY-DANIEL. 1994. Bathycetopsis
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sis, Universidad Central de Venezuela.
SCHAEFER,
S. A. 1990. Anatomy and relationships of
the scoloplacid catfishes. Proc. Acad. Nat. Sci. Phil-
adelphia 142:167-210.
, S. H. WEITZMAN,
AND H. A. BRITSKI. 1989.
Review of the neotropical catfish genus Scoloplax
(Pisces: Loricaroidea: Scoloplacidae) with com-
ments on reductive characters in phylogenetic anal-
ysis. Ibid. 141:181-211.
STEWART, D. 1985. A review of the South American
catfish tribe Hoplomyzontini (Pisces, Aspredini-
dae), with descriptions of new species from Ecua-
dor. Fieldiana, New Series, No. 25(1360):1-19.
TAPHORN, D., AND C. MARRERO. 1990. Hoplomyzon
sexpapilostoma,
a new species of Venezuelan catfish
(Pisces: Aspredinidae), with comments on the Ho-
plomyzontini. Fieldiana, Zoology, New Series 61:
1-9.
(PF) DEPARTMENT OF ZOOLOGY, DUKE UNIVER-
SITY, DURHAM, NORTH CAROLINA 27708; AND
(JGL) DEPARTMENT OF ECOLOGY AND
EVOLUTIONARY BIOLOGY, UNIVERSITY OF
ARIZONA, TUCSON, ARIZONA 85721. PRESENT
ADDRESS: (JPF) DEPARTMENT OF BIOLOGICAL
SCIENCE, FLORIDA STATE UNIVERSITY, Box
3050, TALLAHASSEE, FLORIDA 32306-3050.
Send reprint requests to JPF. Submitted: 24
Aug. 1995. Accepted: 3 Nov. 1995. Section
editor: R. Winterbottom.
648
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... The Hoplomyzontinae is currently composed of four genera: Dupouyichthys (monotypic), Ernstichthys (3 species), Hoplomyzon (4) and Micromyzon (2). Based on morphology (Friel, 1994;Friel and Lundberg, 1996), Hoplomyzon is the first genus to diverge, followed by Micromyzon sister to Dupouyichthys + Ernstichthys. The molecular analyses similarly support Hoplomyzon sister to Ernstichthys + Micromyzon (Dupouyichthys not analyzed). ...
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