The neotropical catfish genus Epapterus Cope (Siluriformes: Auchenipteridae): a reappraisal

16 Pages·1998·6.8 MB·

by  Richard P Vari

PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Ill(4):992-I007. 1998.
The Neotropical catfish genus Epapterus Cope (Siluriformes:
Auchenipteridae): a reappraisal
Richard P. Vari and Carl J. Ferraris, Jr.
(RPV) Department ofVertebrate Zoology, National Museum of Natural History,
Smithsonian Institution, Washington, D.C. 20560, U.S.A.;
(CJF) Department of Ichthyology, California Academy of Sciences, Golden Gate Park,
San Francisco, California 94118, U.S.A.
—
Abstract. The Neotropical auchenipterid catfish genus Epapterus Cope is
reviewed. Epapterus was found to share synapomorphies with Auchenipterus
Valenciennes and Pseudepapterus Steindachner and within that clade it is the
sister-group to Pseudepapterus. Epapterus lacks an adipose dorsal fin, aderived
reductive feature unique to the genus within the clade consisting ofEpapterus,
Auchenipterus, and Pseudepapterus and which is hypothesized to be a syna-
pomorphy for the genus. The extension ofthe interradial membrane tojoin the
contralateral pelvic fins is identified as an additional possible synapomorphy
for Epapterus. Contrary to recent practice, Epapterus is considered to consist
ofonly two species, E. dispilurus Cope (1878) and E. blohmi Vari et al. (1984).
Examination of Epapterus samples from a number of localities in the Rio
Amazonas and Rio Paraguay basins failed to reveal differences between the
populations of the genus in those drainage systems. As a consequence Epap-
&
terus chaquensis Risso Risso (1962), described from the Rio Paraguay sys-
tem, is placed as a synonym of E. dispilurus originally described from the
western portion of the Amazon basin. Euanemus longipinnis Steindachner
(1881) is retained as a synonym ofEpapterus dispilurus as proposed by Stein-
dachner (1882) and Eigenmann & Eigenmann (1888). Epapterus dispilurus is
found to have a broad distribution in the central and western portions of the
Rio Amazonas system and the Rio Paraguay basin. The distribution ofE. bloh-
mi is extended from the state of Guarico, Venezuela to include other portions
ofthe Rio —Orinoco basin and the Rio Tuy ofthe Caribbean coast ofVenezuela.
Resumo. O genero de bagres neotropicais Epapterus Cope e revisado.
Epapterus compartilha varias sinapomorfias com Auchenipterus Valenciennes
e Pseudepapterus Steindachner, e dentro deste grupo e o grupo irmao de Pseu-
depapterus. Epapterus nao possui nadadeira adiposa, uma caracteristica redu-
tiva derivada unica para o genero dentro do grupo composto por Epapterus,
Auchenipterus e Pseudepapterus, e proposta como sinapomorfica para o ge-
nero. A extensao da membrana inter-radial que une as duas nadadeiras pelvicas
e uma outra possivel sinapomorfia para Epapterus. Contrariamente a opiniao
corrente, Epapterus e composto de apenas duas especies, E. dispilurus Cope
(1878) e E. blohmi Vari et al. (1984). O exame de amostras de Epapterus
provenientes de varias localidades no rio Amazonas e Rio Paraguay naorevelou
nenhuma diferen^a entre as popula9oes daquelas duas drenagens. Conseqiien-
&
temente, E. chaquensis Risso Risso (1962), descrito da bacia do Rio Para-
guay, e colocado como sinonimo de E. dispilurus, originalmente descrito da
por^ao ocidental da bacia amazonica. Euanemus longipinnis Steindachner
(1881) e mantido como sinonimo de E. dispilurus conforme proposto porStein-
dachner (1882) e Eigermiann & Eigenmann (1888). Epapterusdispiluruspossui
VOLUME HI, NUMBER 4 993
ampla distribui9ao nas por96es central e ocidental do sistema do rio Amazonas,
assim como na bacia do Rio Paraguay. A distribui^ao geografica de E. blohmi
e ampliada do estado de Guarico, Venezuela, para outras por96es da bacia do
rio Orinoco e ao norte para o Rio Tuy na costa caribenha de Venezuela.
In his original description of the auchen- totype of the latter species published twice
ipterid catfish genus Epapterus fromthe Pe- by Fowler (1941:468, fig. 26; 1945:66, fig.
ruvian Amazon, Cope (1878:677) distin- 26).
guished the genus and its single species Vari et al. (1984) described another spe-
from the other then-known genera now as- cies, E. blohmi, from samples originating in
signed to the Auchenipteridae by a combi- the central portions of the Rio Orinoco sys-
nation of characters, most notably the lack tem. Epapterus blohmi is readily differen-
of the adipose fin, the reduced dorsal fin, tiated from nominal congeners by its dis-
and the absence of jaw teeth. Soon there- tinct caudal-fin pigmentation pattern, a dif-
after Steindachner (1881) described another ference supplemented by other features. In
auchenipterid, Euanemus longipinnis, from their discussion of E. blohmi Vari et al.
specimens collected in the westernAmazon (1984) also commented on the pronounced
along the present Peru-Brazil border. Stein- sexual dimorphism in the species of Epap-
dachner (1882:31) noted that the two nom- terus and noted a series of characters po-
inal species were apparently identical and tentially informative as to the phylogenetic
Eigenmann & Eigenmann (1888:152) for- position of the genus within the Auchen-
mally proposed that Euanemus longipinnis ipteridae. Those authors noted, however,
was a synonym of Epapterus dispilurus. that definitive statements on the questions
&
Soon thereafter Eigenmann Eigenmann of the monophyly and relationships of
(1890) redescribed E. dispilurus on the ba- Epapterus necessitated an encompassing
sis of specimens that they considered to be phylogenetic analysis of the Auchenipteri-
syntypes of Euanemus longipinnis (see, dae, an effort which was beyond the scope
however, under "Remarks" for Epapterus of their study. Vari et al. (1984) also briefly
dispilurus). The seven decades following reported on new locality records forthe two
this series of publications saw only one ci- other Epapterus species {E. dispilurus and
tation ofEpapterus based on additional ma- E. chaquensis) generally recognized as val-
terial, that of Fowler (1940) of a single id at that time, but lacked the population
specimen of E. dispilurus collected in the samples necessary to address the utility of
Rio Ucayali in AmazonianPeru. Thishiatus the purported distinguishing features of
ended when Risso & Risso (1962) de- those species.
scribed E. chaquensis from five specimens In the course of our ongoing studies
&
collected in the Rio Paraguay basin of Ar- within the Auchenipterinae (Ferraris Vari
gentina. Risso & Risso distinguished their 1999) we have been able to examine nu-
nominal species from E. dispilurus on the merous specimens ofEpapterus in addition
basis of purported differences in the num- to those available to previous authors. This
ber of pectoral- and anal-fin rays, relative additional material led to a reappraisal of
eye size, and details of body and fin pig- the distinctiveness of E. dispilurus and E.
mentation. In the absence of available sam- chaquensis. We address that problem here-
ples of E. dispilurus, Risso & Risso com- in, discuss the phylogenetic information
pared E. chaquensis to data in the original pertinent to the monophyly of Epapterus,
description of£. dispilurus by Cope (1878) note broader meristic variation within E.
and a relatively simple drawing of the lec- blohmi revealed by the examination of ad-
994 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
ditional specimens, and report extensions of complex is composed of four centra. The
the known distribution of E. blohmi. fifth centrum is suturally united to the com-
plex and lacks articulated ribs. The firstrib-
Materials and Methods bearing centrum is the sixth vertebra.
Fin-ray counts include all elements and
Materials are listed alphabetically by treat the two posterior most dorsal- and
country and within country by district, anal-fin rays that articulate on the last distal
state, or province, and then repository ab- radial as separate rays. The last pelvic-fin
breviation. Specimen sizes are reported in ray is often branched at its base, which is
standard length (SL). Localities of speci- hidden beneath thick skin. Dissection was
mens, other than type-localities, are trans- sometimes performed to verify the pelvic-
lated into English when listed originally in fin ray count. Caudal-fin ray counts include
another language. Coordinates are either only the branched principal rays. Anal-fin
taken from labels associated with speci- ray counts from sexually mature, trans-
mens, or from publications, information formed males assume that the gonopodium
provided by collectors, or from gazetteers consists of one unbranched and one
when the locality is sufficiently precise. branched ray in the'few instances in which
Institutional abbreviations used are as separate elements could not be discerned
follows: ANSP, Academy of Natural Sci- from radiographs. The posterior most anal-
ences of Philadelphia; MCNG, Museu de fin rays are recorded as branched, although
Ciencias Naturales, Guanare; MCZ, Muse- many were too small and/or fine to discern
um of Comparative Zoology, Cambridge; whether they actually branch. Rudimentary
MHNG, Museum d'Histoire naturelle, Ge- anal-fin rays occur irregularly. Rudiments
neva; MLP, Museo de La Plata; MUSM, that appear to possess a base that articulates
Museo de Historia Natural de la Universi- with a basal radial element were included
dad Nacional Mayor de San Marcos, Lima; in counts, even if the rays do not extend
MZUSP, Museu de Zoologia, Universidade distally to the fin margin. The first two rays
de Sao Paulo; NMW, NaturhistorischesMu- posterior to the gonopodium in males often
seum Wien, Vienna; and USNM, National exhibit this rudimentary development. Ru-
Museum of Natural History, Smithsonian diments suspended in the fin margin and
Institution, Washington, D.C. fully formed rays that do not appear to ar-
Vertebrae and unpaired fin rays were ticulate with a radial element were not
counted, when possible, from radiographs. counted.
Comparative counts made directly from Gill rakers were counted on the first gill
specimens often failed to discern the ante- bar on the right side of the specimen.
rior most anal-fin ray(s) and the posterior Counts included all rakers, including ante-
most dorsal- and anal-fin rays in small spec- rior rudiments.
imens. Vertebral counts were separated into Measurements were made with digital
precaudal and caudal elements. The anterior calipers and were point-to-point, as follows:
most caudal vertebra is the element pos- body depth was taken at the anal-fin origin;
sessing an elongate hemal spine that ex- head length was measured parallel to the
tended just anterior to the first basal radial body axis, from the posteriortip ofthebony
of the anal fin. Usually, the last precaudal operculum to the snout tip; length of anal-
vertebra possesses a markedly shorter he- fin base was measured from the posterior
mal spine than does the first caudal verte- edge of the anus to the insertion of the last
bra, and is the anterior most vertebra with anal-fin ray; orbital width was taken as the
a closed hemal arch. The ural complex is horizontal measure across the middle ofthe
counted as one element. Precaudal and total eye, bounded by the infraorbital bones; pel-
vertebral counts assume that the Weberian vic-fin length represents the distance from
VOLUME 111, NUMBER 4 995
the attachment of the first branched ray to netic relationships and monophyly ofEpap-
the fin tip; pectoral-fin spine length is from terus"" below).
the anterior (or lateral) spine base to the tip Phylogenetic rela—tionships and mono-
of the bony spine not including the fleshy phyly of Epapterus. In his original de-
or flexible bony terminal parts; snout length scription of Epapterus, Cope (1878:677)
is from the snout tip to the anterior margin listed a series of "Char. Gen.", presumably
of the eye. the diagnostic features for the genus. These
Proportional measurements are presented features largely consisted of what would
as percentages of standard length (SL) or now be regarded as various plesiomorphic
head length (HL). Values for the lectotype characters, at least at the level of the Au-
of Epapterus dispilurus are indicated in chenipteridae. Nonetheless, three features
brackets in the description. cited by Cope as distinguishing Epapterus
Nuptial males are those individuals dem- from Euanemus (=Auchenipterus), the lack
onstrating the transitory sexually dimorphic of an adipose fin, the reduced number of
features ofthe maxillary barbels anddorsal- dorsal-fin rays, and the absence of teeth on
fin spine. the jaw and palate, are considered derived
within the Auchenipteridae under the con-
Epapterus Cope text of an encompassing phylogenetic anal-
ysis (Ferraris 1988). Steindachner (1915)
Epapterus Cope, 1878:677 (type species:
subsequently described Pseudepapterus as
Epapterus dispilurus Cope, 1878, by
— & a subgenus ofAuchenipterus. Pseudepapa-
monotypy). Eigenmann Eigenmann,
— & terus shares with Epapterus a lack of jaw
1888:152 [citation]. Eigenman—n Ei- dentition and a reduced dorsal fin but was
genmann, 1890:292 [citation].— Eigen- distinguished from the latter genus on the
mann, 1910:396 [citation]. Fowler
basis of the possession of an adipose fin.
1951:465 [citation].—Vari et al., 1984: Mees (1974:112) commented briefly on the
468 [discussion of relationships and po-
similarities between Auchenipterus, Epa-
tential synapomorphies].
— paterus, and Pseudepapterus. Vari et al.
Diagnosis. Epapaterus along with Au- (1984:467-468) identified a number offea-
chenipterus Valenciennes, in Cuvier and tures in Epapterus ofpotential phylogenetic
Valenciennes (1840) and Pseudepapterus importance. Those authors were unable to
Steindachner (1915) form a monophyletic make definitive statements on these ques-
assemblage within the Auchenipteridae de- tions in the absence of comparative speci-
fined by various synapomorphies (Ferraris mens of Pseudepapterus, and as a conse-
&
1988, Ferraris Vari 1999). The combi- quence of the lack, at that time, of a rig-
nation of the absence ofjaw teeth and the orous hypotheses of higher level groupings
possession ofa reduced dorsal fin with only within the Auchenipteridae.
two to four short rays and a poorly devel- Auchenipterus, Epapterus, and Pseude-
oped spine (other than in nuptial males) de- papterus comprise a monophyletic group
limits a clade formed by Epapterus and within the Auchenipteridae united by vari-
Pseudepapterus within the Auchenipteri- ous characters summarized by Ferraris
dae. The lack of an adipose fin is a syna- (1988) and Ferraris & Vari (1999). The re-
pomorphy for the species of Epapterus duced dorsal fin with only two to four short
within that lineage. Epapterus species also rays and a poorly-developed spine other
have the pelvic fins joined to each other than in nuptial males, along with the lack
across the ventral midline by extensions of ofdentition on both thejaws and palate, are
the interradial membrane; an additional po- derived features within the Auchenipteridae
tential synapomorphy for the members of uniting Pseudepapterus and Epapterus as
the genus (see comments under "Phyloge- sister-taxa. Epapterus has been traditionally
——
996 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
distinguished by its lack of an adipose dor- each other across the ventral midline by ex-
sal fin. An adipose fin is also absent else- tensions ofthe interradial membrane inAu-
where in the Auchenipteridae in Trachel- chenipterusfordicei and Epapterus is most
yopterus Valenciennes, Trachelyopteri- parsimoniously considered a result of con-
chthys Bleeker, and Trachelyichthys Mees vergence.
(the reported absence of the fin in Cerato-
cheilus by Miranda-Ribeiro (1918) was in Key to the species of Epapterus
error; see comments in Ferraris & Vari
(1999). The lack of an adipose fin is con- 1. Dorsal lobe ofcaudal finwithirregularly
rounded patch of dark pigmentation in
sidered synapomorphic for the species of
central portion oflobe, pigmentation not
Epapterus in the clade consisting of Au-
forming distinct transverse bar; ventral
chenipterus, Epapterus, and Pseudepapte- lobe of caudal fin with distinct patch of
rus under the overall most parsimonious dark pigmentation in middle of lobe;
hypothesis of intrafamilial relationships for pectoral-finrays 11 to 13, typically 12 or
the Auchenipteridae (Ferraris 1988). 13 E. dispilurus
Epapterus species also have the pelvic - Dorsal lobe of caudal fin with a dark
fins joined to each other across the ventral transverse bar extending from upper an-
midline by extensions of the interradial terodorsal margin to posterior margin of
membrane. Such continuity of the contra- middle rays of dorsal lobe; ventral lobe
lateral pelvic fins is hypothesized as derived of caudal fin without a distinct patch of
dark pigmentation; pectoral-fin rays 9 to
within the Auchenipteridae given the ab-
11 E. blohmi
sence of a comparable union of the fins in
most auchenipterids and in proximate out-
A
groups to the family. continuity between
Epapterus dispilurus Cope, 1878
the contralateral pelvic fins also occurs else-
Figs. 1-3, Table 1
where within the clade consisting of Au-
chenipterus, Epapterus, and Pseudepapte- Epapterus dispihirus Cope, 1878:677 (type
—
&
rus inAuchenipterusfordicei Eigenmann locality: Peruvian Amazon). Steindach-
Eigenmann (Ferraris &Vari 1999).Auchen- ner, 1882:31 [Euanemus longipinnis
ipterus fordicei, a poorly known species, Steindachner, 1881:17—equated with
shares with its congeners the presence of Epapterus dispilurus]. Eigen—mann &
grooves on the ventral surface of the head Eigenmann, 1888:152 [citation]. Eigen-
that accommodate adducted mental barbels, mann & Eigenmann, 1890:292 [rede-
a synapomorphy for the species ofAuchen- scription based on specimens erroneously
ipterus (Ferraris & Vari 1999). Nuptial thought to—be syntypes ofEuanemus lon-
males ofA. fordicei are unknown and it is gipinn—is]. Eigenmann, 1910:397 [cita-
uncertain whether A. fordicei has the sec- tion]. Fowler, 1915:222 [citation; orig-
ond potential synapomorphy for Auchenip- inal Cope specimens cited as cotypes].
terus, the presence ofpapillae on the dorsal Fowler, 1940:231 [Peru, Rio UcayaH].
and medial surfaces of the ossified maxil- Fowler, 1—941:468, fig. 26 [lectotype des-
&
lary barbel ofnuptial males (Ferraris Vari ignation]. Fowler, 1945:66, fi—g. 26 [re-
1999). Auchenipterusfordicei, nonetheless, production of Fowler, 1941]. Fowler,
lacks the derived features considered syna- 1951:465 [citation].—Bohl—ke, 1984:24
pomorphic for Epapterus and Pseudepap- [type holdings at ANSP]. Vari et al.,
terus and retains a relatively large dorsal fin 1984:470, fig. 2 [Brazil, Ihla da Mar-
and an adipose fin, contrary to the derived chantaria; Peru, Rio Ucayali bas—in; com-
reduction and absence, respectively, of parison with Epapterus blohmi]. Ortega
those structures in Epapterus. Thus, the & Vari, 1986:14 [as component of Peru-
common possession ofpelvic finsjoined to vian freshwater fish fauna].
.
VOLUME 111, NUMBER 4 997
Fig. 1. Epapterus dispilurus, nuptial male, USNM 273591, 106 mm SL; showing pronounced development
ofdorsal-fin spine and maxillary barbel.
Euanemus longipinnis Steindachner, 1881: the dorsal lobe, and by the lack ofa distinct
17 (type locality: Hyavary [^Brazil, patch of dark pigmentation on the ventral
—
Amazonas, Rio Javari]). Steindachner, lobe ofthe caudal fin in E. blohmi. The two
1882:31—[equated with Epapterus dispi- species also differ in the number of pecto-
lurus]. Eigenmann & Eigenmann, ral-fin rays (11 to 13, typically 12 or 13, in
1888:152 [citation—, as synonym ofEpap- E. dispilurus versus 9 to 11 in £. blohmi),
&
terus dispilurus]. Eigenmann Eigen- and in differences, other than for nuptial
mann, 1890:292 [citation,—as synonym of males ofE. dispilurus, in the relative length
Epapterus dispilurus] Eigenmann, of the maxillary barbel (166-194% of HL
1910:397 [citatio—n, as synonym ofEpap- in E. blohmi versus 122-163% of HL in E.
terus dispilurus]. Fowler, 1951:466 [ci- dispilurus). Epapterus dispilurus nuptial
tation, as synonym of Epapterus dispi- males also have a highly developed dorsal
lurus]. spine with well developed basal and distal
&
Epapterus chaquensis Risso Risso, 1962: anterior projections, modifications which
5, figs. 1-3 (type lo—cality: Argentina, are unknown i—n E. blohmi.
&
Chaco, Resistencia). Risso Risso, Description. Body elongate, distinctly
1964:5 [citation].—Vari et al., 1984:470, compressed, head depressed (Figs. 1, 2).
fig. 3 [—Paraguay, Rio Negro of Rio Par- Dorsal profile ofhead flat or barely convex.
aguay]. [not Burgess, 1989, pi. 113, un- Dorsal profile of body from rear of head to
numbered figure]. end ofcaudal peduncle slightly to distinctly
Auchenipterus nuchali—s. Sands, 1984:24, convex. Ventral profile ofhead slightly con-
unnumbered photo. Burgess, 1989; pi. vex. Ventral profile of body gently curved
13. to anal-fin origin. Intromittent organ of
Auchenipterus demerarae. Sands, 1986:43, males extending along entire anterior mar-
unnumbere—d photos. gin ofthird anal-fin ray. Anal-fin base gent-
Diagnosis. Epapterus dispilurus is di- ly convex to caudal peduncle.
agnosed by, and is readily distinguished Greatest body depth 19.3-25.6 [19.6] of
from its single congener, E. blohmi, by hav- SL; snout tip to dorsal-fin origin 19.3-22.5
ing a distinct, irregularly-shaped, patch of [19.7] of SL; snout tip to pelvic-fin origin
dark pigmentation on each caudal-fin lobe 33.2-37.1 [34.0] of SL; snout tip to anal-
which contrasts with the darktransversebar fin origin 39.0-45.6 [39.6] of SL.
extending from the upper anterodorsal mar- Head depressed. Snout viewed from dor-
gin of the dorsal lobe of the caudal fin to sal view somewhat more truncate in mature
the posterior margin of the middle rays of males than in females in which snout mar-
998 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
Fig. 2. Epapterus dispilurus, female, USNM 305651, 102 mm SL; showing form of dorsal-fin spine and
maxillary barbel in females and immature individuals.
gin distinctly rounded from that view. Head cation of barbel highly sexually dimorphic
length 18.3-21.6 [18.9] of SL. Lower jaw (see "Sexual dimorphism" below). Mental
slightly shorter than upper jaw in females barbels four, transversely rounded, arranged
and immature specimens, difference injaw in arc along ventral surface ofjaw, barbels
lengths slightly more pronounced in mature reaching posteriorly approximately to line
males; no teethpresent onpremaxillae, den- through middle of pectoral fin.
taries, vomer, and palatines. Lower pharyn- Lateral line complete, dendritic, with
geal tooth plates large and round with short short side branches atirregularintervals, di-
conical teeth; convex fourth upper pharyn- vided on caudal fin into 2 or 3 branches that
geal tooth plate with short conical teeth. run in some individuals through slightly os-
Snout length 36.2-40.9 [40.7] of HL. Or- sified tubes.
bital margin not free, horizontal width of Dorsal fin greatly reduced, with 1 spine
orbit 26.7-30.2 [29.2] of HL. Length of and 2 or 3 rays (2 rays present in 1 of 43
postorbital portion ofhead 41.5-46.7 [41.5] specimens examined for this feature). Dor-
of HL. Interorbital region gently convex. sal-fin spine non-serrate and sexually di-
Nares ofeach side ofhead separated by dis- morphic, relatively short and slender, length
tance approximately equal to 4.5-5.0 times 2.8-3.6 of SL in females, immatures, and
diameter ofposteriornostril; anteriornostril males not in reproductive condition. Dorsal
somewhat tubular, located on anterodorsal fin proportionally much thicker and dis-
surface of snout, above lip; posterior nostril tinctly elongate in one available nuptial
larger, oval. male, length 16.4 of SL (see "Sexual di-
Gill rakers on first arch 33 to 42. Bran- morphism" below for detailed description
chiostegal rays 6. Gill membranes broadly of spine). First dorsal-fin ray typically
attached to isthmus. Maxillary barbels slightly longer than dorsal-fin spine in fe-
rounded in cross section, elongate, length males and immature specimens. Single
122-163% of HL in females, immature available nuptial male with first dorsal-fin
specimens, and males without fully devel- ray distinctly longerproportionalto SLthan
oped ossification of barbel; barbel length in females, immature specimens, and males
191% of HL in single available nuptial not in reproductive condition, but with
male; tip of barbel reaching posteriorly to, lengthened ray extending only about three-
nearly or to, end of pectoral fin in females, quarters of length of greatly enlarged dor-
immature specimens, and males without sal-fin spine. Adipose dorsal fin absent.
fully developed ossification of the barbel, Pectoral fin with 1 spine and 11 to 13,
extending distinctly beyond tip of pectoral most often 12 [12], rays; pectoral-spine
fin in fully nuptial male; degree of ossifi- length 12.3-14.0 [13.0] of SL; medial mar-
VOLUME 111, NUMBER 4 999
gin of pectoral spine with series of serra- silvery pigmentation nor the white margin
tions, serrations absent basally and some- to the pectoral fin is apparent in the aquar-
times along distal one-fifth of spine; rayed ium specimen ofE. dispilurus published by
portion of fin pointed, longest pectoral-fin Sands (1984:24, photo; identified therein as
rays ranging from approximately same Auchenipterus nuchal—is).
length as, to somewhat longerthan, pectoral Color in alcohol. Overall ground col-
spine; length of longest pectoral-fin rays oration ranging from tan to light purplish
12.3-14.4 of SL; tip of pectoral fin not brown, overall pigmentation tending to in-
reaching to pelvic-fin origin. crease with increasing body size, but with
Pelvic-fin margin pointed, fin with 14 to population samples of similar size individ-
16 rays [15], lateral most rays longest, uals from different sites in the Rio Ucayali
length of longest pelvic-fin rays 16.0-19.3 basin showing notable difference in overall
of SL; pelvic fin with broad, posteroven- intensity of pigmentation.
trally sloping base with interradial mem- Dorsal surface of head in lighter colored
brane continuing across midline of body to specimens with scattered chromatophores
join interradial membrane of contralateral more concentrated lateral to, and particu-
pelvic fin; insertion of pelvic fin situated larly posterior to, fronto-parietal fontanel.
distinctly dorsal of ventral margin of body. Margin of upper lip in region anterior to
Anal-fin margin in females smoothly orbit with distinct patch of dark pigmenta-
convex anteriorly, straight for much of its tion. With increasing intensity of overall
length and convex posteriorly; last un- head and body pigmentation, chromato-
branched and first branched anal-fin rays in phore field on dorsal surface of head ex-
males greatly developed and conjoined for pands laterally and anteriorly to contact or-
support of intromittent organ (see "Sexual bit laterally and patch of pigmentation on
dimorphism" below for details); remainder upper lip anteriorly. In very dark individu-
of anal fin ofmales as in females; length of als entire dorsal portion ofhead dark, other
anal-fin base 51.4-56.0 [55.5] of SL. Anal- than for light anterior margin of upper lip.
fin rays 54 to 61 [59]. Caudal fin distinctly Lateral surface of head with scattered dark
emarginate. chromatophores in light specimens; darker
Precaudal vertebrae 14 to 16, typically 15 specimens with patches of dark pigmenta-
[15], caudal vertebrae 33 to 36 [35], total tion anterior and posterior to orbit contin-
vertebrae 48 to —50 [50]. uous dorsally with dark pigmentation on
Color in life. Sands (1986:43, unnum- dorsal portion of head.
bered photos) published two photographs of Dorsal portion of body with scattered
what is apparently the same individual of dark chromatophores in lighter specimens,
Epapterus dispilurus (identified by that au- but with nearly solid purplish pigmentation
thor asAuchenipterus demerarae). Theseil- in darker individuals. Distinct, dark humer-
lustrations were later reproduced by Bur- al spot present in all individuals; spot
gess (1989, pi. 113, unnumbered photo- slightly horizontally elongate in some
graphs) who identified the species as Au- smaller, lighter-colored specimens, more
chenipterus nuchalis. Overall dark rounded in larger specimens, with posterior
pigmentation on the head and body in spec- portion of spot continuous in some individ-
imen in the photos is as described below uals with variably developed zigzag pattern
for preserved specimens, but with more of dark chromatophores overlying lateral
lightly pigmented portions of body having line. Darker individuals with ventral and
a silvery sheen which also extends onto the sometimes midlateral portions ofbody with
basal portions of the caudal and anal fins. dusky purplish pigmentation.
The anterior margin of the pectoral fin Caudal fin with irregular patch of dark
white. Barbels with white tips. Neither the pigmentation on dorsal lobe; vertical extent
1000 PROCEEDINGS OF THE BIOLOGICAL SOCIETY OF WASHINGTON
of patch usually greater than its horizontal thickened, distinctly curved (Fig. 1), and
length. Ventral lobe of caudal fin with ir- somewhat lengthened relative to the con-
regular patch of dark pigmentation on cen- dition in females. When adductedthebarbel
ter of lobe; shape of patch ranging from of the nuptial male reaches distinctly be-
somewhat rotund to vertically elongate. yond the posterior tip of the pectoral fin.
Caudal pigmentation more intense in spec- The dorsal-fin spine in the single avail-
imens with overall darker coloration. Anal able nuptial male is distinctly thicker and
fin nearly unpigmented in some specimens, more notably is distinctly longer than the
with distal margin darker in most examined spines of immature individuals, females,
specimens. Dark pigmentation on distal and males not in reproductive condition
portions of fin limited to anterior one-half (compare Figs. 1 and 2). The spine in nup-
to two-thirds of fin in some specimens tial males is somewhat sinusoidal in lateral
whereas other individuals have field ofpig- view, with a distinct anterior process to-
mentation along distal region of fin more ward its base and a well developed anterior
elongate, occasionally with fin margin quite process toward its tip which gives the distal
dark along its entire length. Basal portions portion ofthe spine a harpoon-like shape in
ofanal fin purplish in very darkindividuals. lateral view (Fig. 1). The first dorsal-fin ray
Extent of dark pelvic fin pigmentation var- is also distinctly longer in the nuptial male
iable among specimens with differences in than in immature specimens, females, and
degree of development correlated with males not in reproductive condition. The
overall intensity of dark pigmentation of dorsal-fin spine of males can be hyperex-
specimen. Distal margin ofpelvic fin dusky tended anteriorly to an approximately 75°
in all specimens, more so in dark individ- angle relative to the predorsal profile, in-
uals. Lateral margin and basal portions of stead of the vertical or slightly posterodor-
pelvic fin in less intensely pigmented indi- sal fully adducted position of the spine in
viduals with scattereddarkchromatophores. females and juveniles. Mature males have
Pelvic fin with dark patch of pigmentation an anal fin with the last unbranched and the
in more intensely pigmented specimens. first branched anal-fin rays distinctly thick-
Pectoral fin with scattered dark chromato- ened and more elongate than those in fe-
phores more concentrated along distal mar- males and conjoined to form the structural
gin; more intensely pigmented individuals support of an intromittent organ. The gen-
with varyingly developed basal patch of ital pore of males is at the end of an elon-
dark pigmentation. — gate tube that extends along, and is bound
Sexual dimorphism. Females attain a to, the anterior margin of the anal fin. The
greater maximum size than do males. The tube terminates slightly beyond the end of
largest specimen examined by us was a 124 the tip ofthe conjoined last unbranched and
mm
female and a number of females ex- first branched a—nal-fin rays.
ceeded 110 mm. The largest identifiable Distribution. Central and western por-
male was 107 mm and the smallest was 97 tions of the Amazon basin along and south
mm. The snout in nuptial males is some- of the main channel of the Rio Amazonas,
what more truncate when viewed from a and the Rio Paraguay system in Paraguay,
dorsal view than that in females in which northern Argentina, and southern Brazil
the snout margin is distinctly rounded. Fe- (Fig. 3). —
males have the bony core of the maxillary Remarks. Epapterus dispilurus Cope
barbel relatively short with theremainderof (1878) was described on the basis of two
the barbel flexible, thin, and extending pos- specimens which originated in the upper
teriorly to the middle of, or to the posterior Amazon basin of Peru. These specimens
margin of, the pectoral fin. In the single ex- were cited as "cotypes" by Fowler (1915:
amined nuptial male the barbel is greatly 222). Some years later, and without any dis-
VOLUME 111, NUMBER 4 1001
Fig. 3. Map ofcentral portions ofSouth America showing known distribution ofEpapterusdispilurus(type
locality of E. dispilurus inexact = Peruvian Amazon; 1 = type locality of Euanemus longipinnis; 2 = type
locality ofEpapterus chaquensis; some symbols represent more than one locality or lot ofspecimens).
cussion, that author (Fowler 1941:468, fig. Mathematisch-Naturwissenschaftliche
26 repeated in Fowler 1945:66, fig. 26) pro- Klasse for 1882, but Troschel (1882) fisted
vided a cryptic, but valid, lectotype desig- the paper as having been published in 1881.
nation by the statement "tipo, largo 125 Barbara Hertzig (NMW, in litt.) indicated
mm" which accompanied his line drawing that separates ofthe publication were avail-
ofthe species. The cited length corresponds able, and probably distributed, in 1881,
with the total length ofthe larger ofthe two which would account for the date cited in
syntypes of E. dispilurus which we conse- Troschel's account. On the basis ofthis ev-
quently consider to be the lectotype (ANSP idence, we use the year 1881 as the date of
21353). This obscure lectotype designation description of E. longipinnis.
was overlooked in Bohlke (1984). Steindachner (1881:17) indicated that the
The name Euanemus longipinnis is gen- specimens on which he based his descrip-
erally cited as being published in 1882 with tion of the species were sent to him by Ag-
the author credited as being Agassiz in a assiz with the name ''Euanemus longipinnis
Steindachner paper. Both this date and au- Agass." Agassiz's contribution appears to
thor are questionable. The name was pub- be limited to the creation of the name and
lished as the first article of the Denk- sending the specimens to Steindachner giv-
schntten der Akademie der Wissenschaften, en that the format ofthe species description