Copeia, 2006(3), pp. 412–422

The South American (Ostariophysi: Siluriformes: Auchenipteridae), with the Description of a New from the Paraguay River Basin

ROBERTO E. REIS AND THIAGO A. K. BORGES

The Neotropical auchenipterid catfish genus Entomocorus is reviewed and found to include four species widely distributed in lowland cis-Andean South America. Entomocorus benjamini is found in the Madeira River, E. gameroi occurs in the Orinoco River, E. melaphareus is from the lower Amazon River, and a previously undescribed species, E. radiosus, inhabits the upper Paraguay River. Entomocorus is diagnosed based on the shared presence of eight synapomorphies. Entomocorus radiosus is diagnosed by the unique combination of a long anal-fin base, 18–22 branched anal-fin rays, unpigmented pectoral and pelvic fins, and caudal fin hyaline, with distal half of dorsal and ventral lobes pigmented with black. All four species are diagnosed and illustrated, and a key to species is provided.

O geˆnero de Auchenipteridae Entomocorus e´ revisado e inclui quatro espe´cies amplamente distribuı´das em terras baixas da porc¸a˜o cis-Andina da Ame´rica do Sul. Entomocorus benjamini e´ encontrado no rio Madeira, E. gameroi ocorre no rio Orinoco, E. melaphareus e´ do rio Amazonas inferior, e uma espe´cie previamente na˜o descrita, E. radiosus, habita o rio Paraguai superior. Entomocorus e´ diagnosticado com base na presenc¸a compartilhada de oito sinapomorfias. Entomocorus radiosus e´ diagnosticado pela combinac¸a˜o u´nica de uma longa base da nadadeira anal, 18–22 raios ramificados na nadadeira anal, nadadeiras pe´lvicas e peitorais na˜o pigmentadas, e nadadeira caudal hialina com a metade distal dos lobos superior e inferior pigmentados de preto. As quarto espe´cies sa˜o diagnosticadas e ilustradas e uma chave para as espe´cies e´ fornecida.

HE Neotropical catfish genus Entomocorus is a manner similar to that in the other three T currently composed of three species distrib- species. uted in lowland cis-Andean South America. Entomocorus was first diagnosed subsequent to Entomocorus benjamini is endemic to the upper the original description by Britski (1972), who and middle Rio Madeira in Brazil and Bolivia, E. listed characters now considered to be synapo- gameroi occurs in the llanos of the Rı´o Orinoco in morphic for the genus. Ferraris (1988) was the Venezuela, and E. melaphareus was recently de- first to present a phylogenetic diagnosis for scribed from two specimens collected in the Entomocorus, demonstrating its monophyly and lower Amazon. A fourth species, endemic to the including this genus in two nested within Mato Grosso Pantanal area in the upper Rio the auchenipterids: the Auchenipterini and the Paraguay is described in this paper. Entomocorus Auchenipterus-Group. Curran (1989) also includ- are small, nocturnal paelagic auchenipterids ed Entomocorus in his phylogenetic analysis of the feeding near the surface mostly on invertebrates auchenipterids, suggesting a closer relationship (primarily insects) and zooplankton (mainly with Pseudauchenipterus; however, that study was microcrustaceans; Lasso et al., 1995; Resende based on a very limited data matrix and narrow and Pereira, 2000; Pouilly et al., 2003). Secondary taxon sampling, resulting in a weak phylogenetic sexual dimorphism is very prominent in E. hypothesis. No further phylogenetic studies in- gameroi, E. melaphareus, and the new species, cluding Entomocorus have been published, and where transformed males have stiff, ossified the interrelations of its species were never maxillary barbels, an elongated dorsal-fin spine, investigated. The objectives of this paper are to ventrally-directed pectoral-fin spine hooks, very review Entomocorus and to describe a new species elongated pelvic-fin unbranched rays, and a ro- from the upper Rio Paraguay. tated anal-fin base. A detailed description of these traits was presented by Akama and Ferraris MATERIALS AND METHODS (2003). No transformed males of E. benjamini have been examined so far, and it is uncertain Institutional abbreviations are as listed in whether males of this species ever transform in Leviton et al. (1985), with the addition of NUP,

# 2006 by the American Society of Ichthyologists and Herpetologists REIS AND BORGES—A REVIEW OF ENTOMOCORUS 413

Nu´cleo de Pesquisas em Limnologia, Ictiologia e transverse, deep canals in the dorsal surface of Aquicultura, Fundac¸a˜o Universidade Estadual de head, one in the posterior margin of the Maringa´, Maringa´, Brazil. Measurements, counts, supraoccipital and a second in the supraoccipital, and style of the species description in this paper epioccipitals, and the expanded first dorsal-fin follow Akama and Ferraris (2003). An additional pterigiophore; these canals, whose function is character measured is body depth at the origin of unknown, were first identified by Eigenmann the anal fin. Specimens cleared and stained for (1917), who included them in his illustration of inspection of bone and cartilage were prepared the head of E. benjamini, and Ferraris (1988) by the methods of Taylor and Van Dyke (1985). recognized them as a synapomorphy for Entomo- Geographic descriptors and names of localities of corus; (2) an accessory dermal bone at dorsal Spanish speaking countries and in Brazil are surface of the neurocranium at the point of cited in Spanish and Portuguese, respectively. In junction of the frontal, sphenotic, and the supraoc- the lists of specimens examined, the museum cipital (Britski, 1972; Ferraris, 1988); (3) second abbreviation and catalog number is followed by ural element (U2) of the caudal-fin skeleton the total number of specimens in that lot, range present as a fully formed half centrum (Ferraris, of standard length, and the number of specimens 1988; de Pinna and Ng, 2004). Ferraris (1988) measured for the morphometric comparisons in also included the dentition of the premaxilla parentheses. Outgroup specimens examined for reduced to one single row of small conical the assessment of phylogenetic relationships teeth as a derived character, which is also include other auchenipterids listed below as shared by some species of Auchenipterus. As material examined. Epapterus and Pseudepapterus have toothless premaxillae, as a possible further derivation of this character, and as a hypothesis of phyloge- RESULTS netic relationships for the species of Auchenip- Monophyly of Entomocorus.—Entomocorus was in- terus is presently unavailable, it is uncertain cluded by Ferraris (1988) as the genus in whether this trait is synapomorphic for the the Auchenipterus-Group, a further com- Auchenipterus-Group with a reversal in some posed of Auchenipterus, which is the sister-group Auchenipterus species or evolved independently to Epapterus plus Pseudepapterus. This clade is in Entomocorus and some Auchenipterus species. supported by 14 synapomorphies (Ferraris, 1988) In addition, Ferraris (1988) listed two charac- and represents the sister taxon to the Ageneiosus- ters present in transformed, mature males of Group, composed of Ageneiosus and Tetranema- Entomocorus gameroi, which are considered to be tichthys. The sister group to the above clades is synapomorphies: (1) anterior pectoral-fin spine the genus Trachelyopterus, and together they form serrae curved ventrally, with tips directed the tribe Auchenipterini (Ferraris, 1988). ventrally; (2) first pelvic-fin ray enlarged, with Although Entomocorus possesses all 14 synapo- distal segments expanded and flattened, form- morphies of the Auchenipterus-Group, its place- ing a paddle-like structure. These two traits, ment in the family as well as in the Auchenipter- along with a series of additional dimorphic ini is somewhat problematic (Ferraris, 1988). modifications (see detailed description in Entomocorus has apparently lost some characters Akama and Ferraris, 2003) are present in E. that diagnose the Auchenipteridae, such as the gameroi, E. melaphareus, and the new species. No attachment of the urogenital tube to the anterior transformed males of E. benjamini were exam- margin of the anal fin and a branched lateral-line ined. Sexual dimorphism is common among canal on the caudal fin. The urogenital tube is auchenipterids and would represent a plesio- present in all Entomocorus species, but it is free morphic trait in Entomocorus; however, the from the anterior margin of the anal fin. modifications found in mature males of En- Similarly, a bifid epioccipital posterior process, tomocorus are not all paralleled in other a trait synapomorphic for the Auchenipterini, is auchenipterids and represent derived features. absent in Entomocorus, which has the primitive Whether these features represent synapomor- condition of an unbranched epioccipital process phies for the genus, with secondary loss in E. (Ferraris, 1988). benjamini, or a synapomorphy for E. gameroi, E. The monophyly of Entomocorus was first dem- melaphareus, and the new species is not de- onstrated by Ferraris (1988), who presented termined at this time. a phylogenetic diagnosis for the genus, then In addition to the characters listed above, two composed of two species. The features men- other features represent synapomorphies for tioned in Ferraris’ diagnosis were assessed in the Entomocorus: (1) an elongate, posteroventrally two remaining species to verify their generality directed secondary hypurapophysis; outgroups and distribution. These characters are: (1) two examined have a small, anteroventrally directed 414 COPEIA, 2006, NO. 3 secondary hypurapophysis; (2) three or four ral and pelvic fins densely pigmented with black, neural spines just below the adipose fin slightly at least along anterior rays) and from E. radiosus longer than those immediately anterior and by having a shorter anal-fin base (16.5–21.0% SL posterior, providing additional support for the vs. 21.6–27.7% SL) and 14–17 (one specimen adipose fin. In all outgroups examined, the with 18) branched anal-fin rays (vs. 19–22, one neural spines lying below the adipose fin are specimen with 18). comparable in size to the surrounding ones. Despite a detailed analysis of external mor- Distribution.—Entomocorus benjamini is endemic to phology and skeletal anatomy of the four the Rio Madeira basin, in Bolivia and Brazil Entomocorus species that was performed in the (Fig. 3). present study, we were unable to uncover phylogenetically informative traits within the Comments.—No transformed, nuptial males of genus to reconstruct a hypothesis of relationships Entomocorus benjamini are known to date, even for its species. though large specimens collected in all seasons were examined in this and other studies. Pouilly Entomocorus Eigenmann, 1917 et al. (2003, 2004) examined 91 stomachs of E. benjamini in a two-year study in the floodplain Entomocorus Eigenmann, 1917:403. Type species: lakes in the Rı´o Mamore´ basin in Bolivia. They Entomocorus benjamini Eigenmann, 1917 by found aquatic and terrestrial invertebrates (pri- monotypy. marily insects), zooplankton (including cladocer- ans, copepods, and rotiferans), and both aquatic Diagnosis.—Small auchenipterid with and terrestrial vegetation remains, and they the following synapomorphies (most from Fer- classified this species as an invertivore. raris, 1988): (1) two transverse canals in the dorsal surface of the neurocranium, one in the Entomocorus gameroi Mago-Leccia, 1984 supraoccipital and another encompassing the Figure 4, Tables 1–3 supraoccipital, epioccipitals, and the expanded first dorsal-fin pterigiophore; (2) an accessory Entomocorus gameroi Mago-Leccia, 1984:217, figs. dermal bone at the dorsal surface of the head at 1–6 (type locality: mouth of Rio Apurito into the junction of the frontals, sphenotics, and the Rı´o Apure, near San Fernando de Apure, supraoccipital; (3) second ural element (U2) Gua´rico, Venezuela. Holotype: MBUCV V- with a fully formed half centrum; (4) a very 13808). elongate, posteroventrally directed secondary hypurapophysis; (5) three or four neural spines Diagnosis.—This species can be distinguished just below the adipose fin slightly longer than from its congeners by having the caudal fin immediate anterior and posterior ones. The hyaline, with a dark band crossing obliquely from following features are reversals of Entomocorus, the dorsal profile of the caudal peduncle to tip of representing additional synapomorphic traits: middle-upper caudal-fin rays (vs. different color (6) branched lateral-line canal absent on the patterns in remaining species; Fig. 1). It is caudal fin; (7) urogenital tube present but free further distinguished from E. melaphareus by from the anterior margin of the anal fin; (8) an having the pectoral and pelvic fins unpigmented unbranched epioccipital posterior process. (vs. pectoral and pelvic fins densely pigmented with black, at least along anterior rays), and from Entomocorus benjamini Eigenmann, 1917 E. radiosus by having a shorter anal-fin base Figure 2, Tables 1–3 (10.8–20.3% SL vs. 21.6–27.7% SL) and 15–17 branched anal-fin rays (vs. 18–22). Entomocorus benjamini Eigenmann, 1917:403, pl. 41 (type locality: San Joaquin, Bolivia. Holo- Distribution.—Entomocorus gameroi occurs in the type: FMNH 58109). lower Rı´o Orinoco basin of Venezuela, especially in the periodically flooded llanos (Fig. 3). One Diagnosis.—This species can be distinguished lot (UF 33595) apparently belonging to this from its congeners by having the caudal fin species came from the upper R´ıo Meta in hyaline, with distal half of dorsal lobe and Colombia. sometimes distal part of ventral lobe pigmented with black (vs. different color patterns in Comments.—Transformed, nuptial males of En- remaining species; Fig. 1). It is further distin- tomocorus gameroi have been known since the guished from E. melaphareus by having the original description, where secondary sexual pectoral and pelvic fins unpigmented (vs. pecto- dimorphism was carefully described (Mago-Lec- TABLE 1. DESCRIPTIVE MORPHOMETRICS OF Entomocorus radiosus, E. benjamini, E. gameroi, AND E. melaphareus. Values are given as percents of standard length or of head length. SD 5 standard deviation. TM 5 transformed male (n 5 1). TM are not included in range and mean. Holotype of E. melaphareus is a TM. Data in bold are distinguishing features.

E. radiosus n 5 27 E. benjamini n 5 22 Male E. gameroi n 5 8 Female E. gameroi n 5 12 E. melaphareus REIS Character Hol TM Low High Mean SD Low High Mean SD TM Low High Mean SD Low High Mean SD Hol Par

Standard length (mm) 45.0 52.9 35.8 51.0 40.2 41.0 56.9 48.5 52.8 50.3 58.4 54.2 39.5 57.3 47.4 57.5 42.7 AND Percents of standard length Head length 23.6 23.1 21.5 24.5 23.0 0.7 22.8 26.2 24.6 0.8 25.6 23.6 25.6 24.8 0.7 22.8 26.2 24.5 0.9 26.1 26.5 BORGES—A Body depth at dorsal fin 25.6 23.2 22.6 26.3 24.3 0.9 23.0 25.9 24.6 0.8 24.1 24.0 25.6 24.9 0.5 23.2 26.4 24.9 0.8 22.8 25.3 Body depth at anal fin 28.4 27.0 24.6 28.9 26.7 1.1 23.3 29.1 27.1 1.6 27.3 27.6 29.9 28.7 0.8 26.3 30.1 28.0 1.0 24.9 24.8 Body width at cleithrum 19.1 18.3 18.0 20.4 18.8 0.6 19.4 21.6 20.5 0.6 20.6 20.1 21.1 20.8 0.3 20.1 21.6 20.7 0.5 20.9 22.2 Predorsal length 31.1 31.2 29.9 32.1 31.3 0.5 30.6 33.9 32.4 0.9 31.4 30.7 34.0 32.3 1.1 31.0 34.5 32.7 1.2 32.2 34.9

Prepectoral length 23.6 24.9 23.1 25.8 24.6 0.7 23.0 27.2 25.1 1.1 26.9 25.0 27.2 26.0 0.6 24.8 26.9 25.9 0.8 28.2 26.9 REVIEW Pectoral-fin spine length 19.3 20.0 17.0 24.3 21.1 1.6 20.2 24.0 21.7 1.0 23.1 21.0 23.7 22.5 1.0 20.8 25.5 23.0 1.4 19.8 22.5 Dorsal-fin spine length 15.3 30.2 15.3 18.0 17.1 0.6 17.2 21.2 19.0 1.4 29.5 19.0 21.7 20.2 1.2 17.7 20.6 19.0 1.0 31.1 21.5 First pelvic-fin ray length 15.8 34.8 14.2 17.6 15.9 1.0 15.0 19.5 16.9 1.0 43.2 19.7 24.6 22.0 2.0 15.2 19.5 16.9 1.3 47.5 20.4

Caudal peduncle height 14.0 13.2 12.3 15.0 13.5 0.7 12.3 15.1 14.0 0.7 13.8 13.9 15.2 14.6 0.4 13.8 15.1 14.3 0.4 12.2 13.3 OF Caudal peduncle length 15.6 15.5 13.7 18.2 15.5 1.0 15.7 18.4 16.9 0.7 15.7 14.3 17.1 15.6 0.8 14.3 18.0 16.0 1.0 17.7 17.1 ENTOMOCORUS Adipose-fin base length 10.9 8.7 6.9 11.7 9.2 1.1 8.2 12.0 9.7 1.1 9.8 8.9 11.3 10.2 0.8 9.1 10.9 9.9 0.7 9.6 8.0 Adipose fin height 4.0 4.9 3.6 6.1 4.5 0.7 4.4 6.4 5.3 0.5 6.8 4.4 6.2 5.4 0.6 3.7 6.4 5.4 0.8 6.4 4.9 Anal-fin base length 23.6 18.5 21.6 27.7 25.2 1.6 16.5 21.0 18.8 1.3 10.8 15.7 18.8 16.8 1.1 17.2 20.3 18.7 1.0 9.9 15.9 Percents of head length Horizontal eye diameter 38.7 36.9 32.6 41.4 36.3 2.2 31.0 37.5 33.6 1.8 37.0 32.0 36.6 35.0 1.8 31.7 37.9 34.5 1.9 36.0 37.2 Snout length 37.7 41.0 31.3 43.8 39.5 2.6 37.7 45.8 41.6 1.9 40.7 38.5 41.3 39.7 0.8 37.9 46.8 41.8 2.4 42.0 42.5 Bony interorbital width 45.3 41.8 41.3 46.3 43.8 1.5 42.5 49.6 47.1 1.9 41.5 47.5 51.4 48.8 1.3 44.2 53.8 50.2 2.7 45.5 44.2 415 416 COPEIA, 2006, NO. 3

TABLE 2. FREQUENCY DISTRIBUTION OF VARIABLE COUNTS OF Entomocorus radiosus, E. benjamini, E. gameroi, AND E. melaphareus. Fin rays and spine serrae.

Anal-fin Pectoral-fin spine anterior Pectoral-fin spine posterior unbranched rays Anal-fin branched rays serrae serrae 4 5 6 7 14 15 16 17 18 19 20 21 22 16 17 18 19 20 21 13 15 16 17 18 19

E. radiosus 8 18 1 1 4 7 11 4 4 7 9 5 1 5 8 11 2 E. benjamini 7 12 3 2 8 8 3 1 4 3 3 5 3 2 3 4 7 6 E. gameroi 1 11 9 10 6 5 3 3 7 2 3 1 2 2 10 3 E. melaphareus 1 1 1 1 1 1 1 1 cia, 1984). During a 1.5-yr study in the lago remaining species; Fig. 1). It is further distin- Terecaya, lower Rı´o Orinoco, Rodriguez et al. guished from E. radiosus by a shorter anal-fin base (1990) examined the contents of eight stomachs (9.9–15.9% SL vs. 21.6–27.7% SL) and 14–15 of E. gameroi and classified the species as branched anal-fin rays (vs. 18–22). zooplanktivore. They found cladocerans, cope- pods, and water mites and noted that a single fish Distribution.—Entomocorus melaphareus is known could ingest as many as 1700 planktonic crusta- only from the holotype and one paratype from ceans in a single night, when this species feeds the lower Amazon (Fig. 3). near the water surface. Lasso et al. (1995) reported on the stomach contents of 27 individ- Comments.—The holotype of E. melaphareus is uals of E. gameroi from the vicinity of Can˜o a transformed, nuptial male. Secondary sexual Guaritico in the Apure State, Venezuela. They dimorphism was described in detail by Akama found cladocerans, ostracods, insects (coleopter- and Ferraris (2003). Nothing is known to date ans, dipterans, ephemeropterans, hemipterans, about diet or feeding habits of this species. and unidentified insects), seeds, and other vegetal matter and classified the species as an omnivore with a tendency towards insectivory. Entomocorus radiosus, new species Figure 6, Tables 1–3 Entomocorus melaphareus Akama and Ferraris, 2003 Holotype.—MCP 35902, 45.0 mm SL, Brazil, Mato Figure 5, Tables 1–3 Grosso, Rio Paraguay at neighborhoods of Ca´ceres, approx. 16u039S, 057u429W, 11 Aug. Entomocorus melaphareus Akama and Ferraris, 1991, R. E. Reis, L. R. Malabarba, N. A. Menezes, 2003:78 fig. 1 (type locality: Brazil, Para´ State, M. Weitzman, and F. A. Machado. Monte Alegre, left bank of the Amazon River at Costa do Curua´, 2u13946.20S, 054u01927.60W. Paratypes.—MCP 24296, 9+1 CS, 35.8–40.4 mm Holotype: MZUSP 76413). SL (9), collected with the holotype. MCP 35903, 1, 38.9 mm SL (1), Brazil, Mato Grosso, creek Diagnosis.—This species can be distinguished trib. to Rio Aguapeı´ on road MT 265, from its congeners by having distinctly black- 15u53956.50S, 058u36929.60W, 11 July 2004, R. E. pigmented pectoral and pelvic fins, at least along Reis, E. H. L. Pereira, F. Langeani, and P. A. anterior rays (vs. pectoral and pelvic fins un- Buckup. MCP 35904, 9+1 CS, 31.7–51.0 mm SL pigmented), and caudal fin hyaline, with an (5) and NUP 2216, 24, 23.3–39.5 mm SL (3), inconspicuous patch of black chromatophores Brazil, Mato Grosso, Bara˜o de Melgac¸o, Sinha´ on the dorsal lobe (vs. different color patterns in Mariana Bay on Rio Cuiaba´, 16u20920.50S,

TABLE 3. FREQUENCY DISTRIBUTION OF VARIABLE COUNTS OF Entomocorus radiosus, E. benjamini, E. gameroi, AND E. melaphareus. Vertebrae and procurrent caudal-fin rays (counted in cleared-and-stained or x-rayed specimens only).

Vertebrae Dorsal procurrent rays Ventral procurrent rays 38 39 40 16 17 18 19 20 14 15 16 17

E. radiosus 2 2 2 E. benjamini 1 1 1 1 1 1 E. gameroi 2 2 2 E. melaphareus 1 1 2 2 REIS AND BORGES—A REVIEW OF ENTOMOCORUS 417

Fig. 2. Entomocorus benjamini, MCP 35774, 56.9 mm SL, Rio Guapore´ near bridge from Pontes e Lacerda to Vila Bela da Santı´ssima Trindade, Mato Grosso, Brazil.

055u54910.30W, 25 May 2000, Nupelia techni- cians. MCP 38966, 3, 42.9–52.9 mm SL (1), Brazil, Mato Grosso, Bara˜o de Melgac¸o, Sinha´ Mariana Bay on Rio Cuiaba´, approx. 16u209S, 055u549W, 20 Nov. 2003, Nupelia technicians. MZUSP 36353, 1, 41.1 mm SL (1), Brazil, Mato Grosso do Sul, Corumba´, Lada´rio at Codrasa, Sept. 1985, G. M. Moura˜o, E. K. Bastos, and R. A. Mauro. MZUSP 52519, 6, 38.1–45.6 mm SL (6), Brazil, Mato Grosso do Sul, Pantanal de Paiagua´s, Rio Piquiri at Santo Antoˆnio Farm, 29 Sept. 1995, T. Lipparelli.

Diagnosis.—The new species can be distinguished from its congeners by having a longer anal-fin base (21.6–27.7% SL vs. 9.9–21.0% SL); 19–22 (one specimen with 18) branched anal-fin rays (vs. 14–17, but one specimens of E. benjamini with 18); and caudal fin hyaline, with distal half of dorsal and ventral lobes pigmented with black (vs. different color patterns in remaining species; Fig. 1). It is further distinguished from E. melaphareus by having the pectoral and pelvic fins unpigmented (vs. pectoral and pelvic fins densely pigmented with black, at least along anterior rays).

Description.—Morphometric data summarized in Table 1; variable counts in Tables 2 and 3. Head and body shape, form and position of fins, and pigmentation pattern illustrated in Figure 6. Body robust, short; head depressed anteriorly, trunk and caudal peduncle progressively more compressed towards caudal fin. Lateral line complete and midlateral; canal forming irregular zig-zag pattern, with oblique, short, posteriorly directed branches. Lateral-line canal not bifur- cating at caudal-fin base. Total vertebrae 40, 4 in

r

Fig. 1. Schematic drawing of caudal-fin color pattern of Entomocorus. (A) E. benjamini; (B) E. gameroi; (C) E. melaphareus; and (D) E. radiosus. 418 COPEIA, 2006, NO. 3

both medially and laterally; tooth in lower jaw in one row laterally, becoming two and then three irregular rows at symphysis. Dorsal-fin origin located posterior to vertical through opercular flap, approximately on verti- cal through middle of cleithral posterior process. Dorsal-fin spine slender, straight; its anterior margin smooth, posterior margin with medial row of widely spaced and reduced serrations. Dorsal fin with five branched rays, last very small. Adipose fin relatively large and triangular to oval- shaped. Caudal fin deeply forked, lobes pointed. Out- ermost simple rays twice as long as middle rays. Dorsal caudal-fin lobe slightly longer than lower. Caudal fin with seven upper and eight lower (one specimen with seven) branched rays. Procurrent Fig. 3. Geographic distribution of Entomocorus caudal-fin rays 17 upper and 14 lower (counted species. Triangles: E. benjamini; Circles: E. gameroi; in two cleared-and-stained specimens). Inverted triangles: E. melaphareus; and Squares: E. Anal-fin base long (but still short among radiosus. One symbol can represent more than one auchenipterids), its length approximately equal lot or locality. Open symbols represent non-exam- to head length. Anal-fin origin located well in ined records from collection databases. T 5 type locality. advance of the adipose-fin origin. Last un- branched and first branched anal-fin rays lon- gest; rays decreasing slightly in length posteriorly. Weberian complex, 7–8 additional precaudal (6– Anal-fin margin straight to slightly convex. Anal 7 with ribs), and 28–29 caudal (counted in two fin with five or six (one specimen with seven) cleared and stained specimens). unbranched, and 19 to 22 (one specimen with Head profile straight from snout tip to dorsal- 18) branched, rays. fin origin. Snout length slightly longer than Pelvic-fin margin rounded, first branched ray orbital diameter, snout margin rounded in dorsal longest; one unbranched and five branched rays. view. Eye large, lateroventrally placed, more Pelvic-fin origin located at or slightly posterior to visible from ventral than from dorsal view. vertical through base of last dorsal-fin ray. Barbels slender, maxillary barbel extending to Pectoral fin with one stout spine and eight or slightly beyond anal-fin origin; mental barbels (one specimen with seven) branched rays; first extending to pectoral-fin base, outer one some- branched ray longest, remaining rays decreasing times slightly longer. Branchiostegal membrane in size. Spine serrated along both margins, broadly attached to isthmus. Gill opening rela- antrorse serrae with 17–21 dentations on anterior tively wide, its ventral margin extending ventral margin and retrorse serrae with 15–18 dentations to horizontal through pectoral-spine base. Mouth on posterior margin. terminal to slightly subterminal, with upper jaw extending slightly beyond lower jaw. Teeth of Coloration in alcohol.—Ground color of head and upper jaw visible when mouth closed. Jaw teeth body pale yellowish. Middorsal line with wide minute, barely extending through epidermal black stripe extending from dorsal-fin origin to tissue; teeth in one irregular row in upper jaw base of upper caudal-fin rays; continuing from that point ventrally, on base of caudal-fin rays as cloud of dispersed chromatophores. Lateral and ventral surfaces of body with fine scattered dark pigmentation of variable intensity but more concentrated on dorsal portion of body; some individuals more heavily pigmented with indis- tinct blotches formed by concentrations of black chromatophores on flanks. Subcutaneous darker line present at midlateral line. Dorsal surface of head with large middorsal black spot extending Fig. 4. Entomocorus gameroi, INHS 30016, from posterior limit of cranial fontanel to base 50.3 mm SL, Can˜o Hondo, tributary to Rı´o Apure, of supraoccipital spine. Dorsal surface of snout Agua Negra, Barinas, Venezuela. with paired, dark ovoid spot extending between REIS AND BORGES—A REVIEW OF ENTOMOCORUS 419

Fig. 5. Entomocorus melaphareus, holotype, MZUSP 76413, 58.6 mm SL, transformed male, Rio Amazonas, Costa do Curua´, Monte Alegre, Para´, Brazil. anterior and posterior nares. Dorsal and lateral tions. In a 15-month study, Resende and Pereira surfaces of head with scattered dark chromato- (2000) examined stomach contents of 111 speci- phores, especially postorbitally. Dorsal, anal, mens of E. radiosus (identified as E. benjamini), pectoral, and pelvic fins hyaline; heavily pigmen- from the Rio Miranda basin, in southern ted individuals sometimes with scattered black Pantanal. Of these, 72 individuals had contents chromatophores on spine and outer rays of in their stomachs. The overall predominant item pectoral fin and on tip of pelvic-fin rays. Adipose consumed was microcrustaceans (cladocerans, fin with some scattered pigmentation, especially copepods, and ostracods). Secondary items were along base. Caudal fin with distinct black band insects (ephemeropterans, coleopterans, and on distal half of dorsal and ventral lobes, hemipterans). Other noted stomach items in beginning approximately at tip of middle cau- small and/or sporadic amounts include: water dal-fin rays. Barbels with scattered dark chroma- mites, rotifers, fish scales, bryozoans, unidenti- tophores, appearing pale or dusky. fied eggs, unidentified items, detritus, and sand. The species was noted to be a zooplanktivore Coloration in life.—Living specimens with same which also eats insects. pigmentation patterns as described above, but head and body bright white; large middorsal Etymology.—The specific epithet of E. radiosus is spot extending from posterior limit of cranial from the Latin radius, meaning rod, fin-ray, and fontanel to base of supraoccipital spine silvery -osus, having the nature or quality of something, dark. Caudal-fin band darkly pigmented, strongly usually in fullness or abundance, in allusion to contrasting with white color of body. the many anal-fin rays presented by this species. An adjective. Distribution.—Entomocorus radiosus is endemic to the Rio Paraguay basin (Fig. 3). KEY TO THE SPECIES OF Entomocorus

Ecology.—Except for lot MCP 35903, which was 1a. Anal-fin base long (21.6–27.7% SL, but caught in a creek, specimens were collected in shorter in transformed males), with 19– wide open environments, as river channels and 22 (rarely 18) branched rays ______bays of the upper Rio Paraguay basin, in the ______E. radiosus, new species (Paraguay basin) periodically flooded areas known as the Pantanal. 1b. Anal-fin base short (15.9–21.0% SL, but No specimens of Entomocorus radiosus are known shorter in transformed males), with 14– from the lower portions of the Rio Paraguay 17 (rarely 18 in E. benjamini) branched basin south of the Pantanal, either in Brazil, rays ______2 Bolivia, or Paraguay. Only one transformed male 2a. Pectoral and pelvic fins densely pigmen- is known of Entomocorus radiosus (MCP 38966, ted with black chromatophores, at least

52.9 mm SL, Fig. 7), suggesting that transformed along anterior rays ______males are comparatively rare in natural popula- ______E. melaphareus (Lower Amazon) 420 COPEIA, 2006, NO. 3

Fig. 6. Entomocorus radiosus, holotype, MCP 35902, 45.0 mm SL, Rio Paraguay at neighborhoods of Ca´ceres, approx. 16u039S, 057u429W, Mato Grosso, Brazil.

2b. Pectoral and pelvic fins hyaline or slightly upper caudal-fin rays (Fig. 1) ______

pigmented with black______3 ______E. gameroi (Orinoco basin) 3a. Caudal fin hyaline, with distal half of dorsal and sometimes ventral lobes pig- MATERIAL EXAMINED mented with black (Fig. 1)______E. benjamini (Madeira basin) Ageneiosus sp.: MCP 36338, 3+1 CS, Brazil, Acre, 3b. Caudal fin hyaline with a dark band Bujari, Rio Purus basin, Rio Riozinho do Andira´. crossing obliquely from the dorsal profile Auchenipterus osteomystax: MCP 13556, 1 CS, of the caudal peduncle to tip of middle- Brazil, Rio Grande do Sul, Roque Gonzales, Rio REIS AND BORGES—A REVIEW OF ENTOMOCORUS 421

Fig. 7. Transformed male of Entomocorus radiosus, paratype, MCP 38966, 52.9 mm SL, Sinha´ Mariana Bay on Rio Cuiaba´, Bara˜o de Melgac¸o, Mato Grosso, Brazil.

Uruguay basin. Epapterus dispilurus: MZUSP Monte Alegre, Rio Amazonas at Costa do Curua´, 26410, 6+1 CS, Peru, Loreto, Rı´o Ucayali near 7 March 2002; MZUSP 76445, 1, 42.7 mm SL Pucallpa; MZUSP 40084, 8, Brazil, Mato Grosso (paratype) (1), Brazil, Amazonas, Rio Amazonas do Sul, Rio Aquidauana, baia da Onc¸a. Entomo- between Itacoatiara and Parintins, 13 March corus benjamini: MZUSP 27817, 6+1 CS, 41.0– 2002. Pseudepapterus cucuyhensis: MZUSP 53311, 48.6 mm SL (3), Bolivia, Trinidad, Canal San 19+1 CS, Brazil, Amazonas, Cuieiras, Rio Negro. Gregorio, 27 April 1983; USNM 305539, 41, 37.4– P. hasemani: MZUSP 53323, 11+1 CS, Brazil, Para´, 50.3 mm SL (3), Bolivia, Beni, Rio Matos, trib. Porto de Moz, Rio Xingu basin, Rio Acarai. Tatia Rio Mamore´, Prov. Ballivia, 28 Aug. 1987; USNM boemia: MCP 12949, 13+2 CS, Brazil, Rio Grande 305655, 26, 21.8–51.4 mm SL (3), Bolivia, Beni, do Sul, Esmeralda, Rio Pelotas. Trachelyopterus Prov. Ballivia, Rio Matos, trib. Rio Mamore´, 24 lucenai: MCP 15432, 9+1 CS, Brazil, Rio Grande Aug. 1987; MCP 35773, 1, 49.6 mm SL (1), do Sul, Porto Alegre, ilhas das Flores, Rio Jacui. Brazil, Rondoˆnia, Jaci-Parana´, Rio Jaci-Parana´, T. galeatus: MCP 12402, 16+1 CS, Brazil, Rio trib. Rio Madeira, 18 July 2004; MCP 35774, 10, Grande do Sul, Pirapo´, mouth of Rio Ijuı´-Mirim. 47.2–56.9 mm SL (10), Brazil, Mato Grosso, Rio Tetranematichthys wallacei: MCP 27174, 2, Brazil, Guapore´ near bidge from Pontes e Lacerda to Para´, Rio Guama´ near Oure´m; MCP 37471, 1, Vila Bela da Santı´ssima Trindade, 11 July 2004; Peru, Loreto, Jenaro Herrera, Quebrada Sapue- MZUSP 27913, 2, 42.0–45.2 mm SL (2), Brazil, nilla. Amazonas, Humaita´, Igarape´ Joari, July 1975; MZUSP 48907, 1, 33.3 mm SL (1), Brazil, ACKNOWLEDGMENTS Amazonas, Igarape´ Aranaguara, trib. Rio Madei- ra, 26 Aug. 1976. E. gameroi: MCP 17459, 3, 39.5– We are much indebted to C. Pavanelli, L. Page, 42.3 mm SL (3), Venezuela, Apure, Otto Mun˜oz, M. de Pinna, M. Sabaj, O. Oyakawa, R. Vari, and dique NE in the Modulo Unellez, 3 Feb. 1981; S. Jewett for loan and exchange of specimens. MCP 15135, 7+1 CS, 50.9–58.4 mm SL (7), The manuscript benefited from the critical Venezuela, Anzoategui, Soledad, Rio Orinoco review of C. Ferraris, Jr., L. Finley helped with basin, Laguna Terecaya, 22 May 1986; INHS literature and data on ecology and feeding, and 30016, 10, 43.2–54.2 mm SL (one transformed C. Moreira assisted with the x-ray machine at male 52.8 mm SL) (6), Venezuela, Barinas, Agua MZUSP. Some specimens used in this study were Negra, Can˜o Hondo, trib. Rı´o Apure, 14 Jan. captured under IBAMA collecting permit 054/ 1993; INHS 29255, 15, 42.2–57.3 mm SL (5), 2004 to RER. Part of the fieldwork and research Venezuela, Portuguesa, Puerto Papelon, Can˜o associated with this paper were supported by Igues, trib. Rı´o Apure, 17 Dec. 1992; INHS the FINEP/CNPq (Pronex #661058/1997-2) 28072, 16, 28.1–39.6 mm SL, Venezuela, Apure, and the All Catfish Species Inventory (NSF-DEB 58 km SSW Bruzual, Can˜o Guaritico, trib. Rı´o #0315963). The authors are partially financed by Apure, 4 Jan. 1992. E. melaphareus: MZUSP 76413, CNPq (RER, process #305344/87-0 and TAKB, 1, 57.5 mm SL (holotype) (1), Brazil, Para´, Program PIBIC-CNPq). 422 COPEIA, 2006, NO. 3

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