Description of five new species of Acestrocephalus Eigenmann and redescription of A. sardina and A. boehlkei (Characiformes: Characidae)

385 Neotropical Ichthyology, 4(4):385-400, 2006 Copyright © 2006 Sociedade Brasileira de Ictiologia Description of five new species of Acestrocephalus Eigenmann and redescription of A.sardina and A.boehlkei (Characiformes: Characidae) Naércio A. Menezes Acestrocephalus maculosus,A. stigmatus,A. nigrifasciatus,A. acutus, and A. pallidus are described as new species and A. sardina and A. boehlkei are redescribed. Acestrocephalus ginesi is considered synonymous with A. sardina. Specimens of Acestrocephalus anomalus, a valid trans-Andean species, were not available for study. Acestrocephalus stigmatus,A. maculosus, and A. boehlkei have a dark humeral blotch not present in the remaining species and the species within the two species groups thus characterized are told apart by meristic and morphometric data as well as morphological structures associated with the pseudotympanum. Acestrocephalus maculosus,A. stigmatus,A. nigrifasciatus,A. acutus e A. pallidus são descritas como espécies novas, e A. sardina e A. boehlkei são redescritas. Acestrocephalus ginesi é considerada sinônimo de A. sardina. Não foram conseguidos para estudo exemplares de Acestrocephalus anomalus, espécie transandina válida. Acestrocephalus stigmatus,A. maculosus eA. boehlkei possuem uma mancha umeral escura que não está presente nas demais espécies e as espécies nos dois grupos de espécies caracterizados desta forma, são separadas através de dados merísticos e morfométricos, bem como estruturas morfológicas associadas com o pseudotímpano. Key words: Freshwater fish, South America, Brazil, Taxonomy, Systematics. Museu de Zoologia, Universidade de São Paulo, Caixa Postal 42594, 04218-970 São Paulo, Brazil. e-mail: [email protected] Introduction The genus Acestrocephalus Eigenmann was included with Galeocharax Fowler and Cynopotamus Valenciennes in the subfamily Cynopotaminae by Menezes (1976). Although not using a truly cladistic approach Menezes, based on a morphological character survey, considered the group monophyletic. In a subsequent contribution Lucena & Menezes (2003) did not recognize Cynopotaminae and the three genera formerly representing the subfamily were included in the characid subfamily Characinae. The phylogenetic relationships of all the characin genera have yet to be studied and as reported by Lucena & Menezes (2003) monophyly of the group is uncertain. Preliminary examination of the genera within the Characinae indicates that certain characters used by Menezes (1976) to define Cynopotaminae, including presence of ctenoid (actually spinoid) scales, shape, number and arrangement of premaxillary and dentary teeth and structure of the gill-rakers might be exclusive to Acestrocephalus,Galeocharax and Cynopotamus, suggesting that these genera are much more closely related among themselves than to any other genus in the Characinae. Acestrocephalus is presently represented by four species: A.anomalus (Steindachner), A.sardina (Fowler), A.boehlkei Menezes, and A.ginesi Lasso & Taphorn. Five new species were discovered in material recently collected in expeditions carried out in different regions of Brazil. Additional specimens of A.sardina and A.boehlkei were also obtained. The type specimen of A.sardina, a juvenile (31.4 mm SL) not previously seen by me was examined and photographed by my colleague Heraldo Britski. Recognition of new species and new data from A.sardina and A. boehlkei allowed for a better characterization of the species in the genus, with exception of A.anomalus as new material and previously examined specimens were unavailable. Herein, the five new species of Acestrocephalus are described and A.sardina and A. boehlkei are redescribed. Description of five new species of Acestrocephalus 386 Materials and Methods This research is based on specimens examined from the following institutions: Museu de Zoologia, Universidade de São Paulo, São Paulo (MZUSP); Museu Nacional, Rio de Janeiro (MNRJ); Museu de Ciências e Tecnologia, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre (MCP). Counts, measurements, and presentation of data follow Fink & Weitzman (1974) and Menezes (1976, 1977), unless otherwise stated. The number of scales above and below lateral line and around caudal peduncle correspond to the number of horizontal scale rows. The number of gill-rakers includes only developed elements, not rudiments in both the upper and lower gill-arches. Examination of mature males under the stereomicroscope did not reveal the presence of gill glands on the first gill-arch. Measurements were taken whenever possible on the left side of the specimens, using dial calipers, recorded to a tenth of a millimeter and expressed as percentages of standard length (SL), except for subunits of the head, expressed as percentages of head length (HL). Data from Acestrocephalus anomalus and A. boehlkei in part were extracted from Menezes (1976, 1977). All measurements were taken point to point. Meristic and morphometric data of males and females were treated separately to assess possible differences between sexes, but none were found. Immature as well as males and females were recognized by examination of gonads under the stereomicroscope. Vertebral counts were taken from radiographs and include the four vertebrae of the Weberian apparatus and the terminal “half centrum”. To show the arrangement of the muscles around the pseudotympanum the skin and adipose tissue covering the muscular hiatus were carefully removed and all muscles exposed (Fig. 1). In the schematic drawings prepared for each species muscles and other structures are represented as they appear after removal of skin and adipose tissue. The structure of the pseudotympanum does not seem to vary ontogenetically as no major differences were found in specimens of different sizes in all species examined. In the descriptions, counts pertaining to the holotype are presented first, followed in parentheses by the mean of the sample, range, and the total number of specimens counted. The statistical procedure was standardized for comparative purposes even though samples of some species are represented by very few specimens. Results Acestrocephalus Eigenmann, 1909 Acestrocephalus Eigenmann, 1910:447. Type species: Xiphorhamphus anomalus Steindachner, 1880. Type by original designation. Gender: masculine. Diagnosis. Acestrocephalus can be distinguished from the remaining genera of the Characinae sensu Lucena & Menezes (2003) by the following unique combination of morphological characters extracted from Menezes (1976: 37) with the addition of new ranges of meristic and morphometric characters for the genus due to the values of the new species described herein. Body comparatively small (SL 31.4-135 mm); anterior dorsal region not elevated; dorsal body profile regularly curved from tip of snout to caudal base; lower part of antorbital only in contact with maxilla; first infraorbital relatively short, high on its median part; nasal bone tubular; cleithrum not notched, just with a slight sinuosity along its ventral edge; ectopterygoid with a median ventral bony crest; supraoccipital spine short; dentary with two rows of teeth, anterior teeth of external row much larger than posterior ones; first and third anterior teeth canine-like, more developed than the other two; posterior dentary tooth row with 20-40 small conical teeth slightly curved posteriorly, their number tending to increase with an increase in standard length; inner row of teeth on dentary formed by 7-14 small conical teeth; scales comparatively large and numerous, perforated lateral-line scales 67-79, 10-15 above and 9-13 below lateral line; anal fin comparatively short, with iv-v,25-36 rays, its origin situated on vertical line always crossing behind middle of dorsal-fin base length; pectoral fin with i,11-16 rays. Fig. 1.Acestrocephalus maculosus, MNRJ 12657, paratype, 44 mm SL. External view of muscles covering the anterior portion of the swim bladder. Anterior towards left; skin and adipose tissue removed. Fig. 2.Acestrocephalus sardina, ANSP 39307, holotype, 31.4 mm SL; rio Madeira, Brazil. N. A. Menezes 387 Key to species of Acestrocephalus 1. A black spot at humeral region slightly posterior and dorsal to pseudotympanum, very small and sometimes indistinct in very young specimens .....................................................2 1’.No black spot at humeral region ......................................... 4 2. Horizontal scale rows around caudal peduncle 24-25; 10-12 small conical teeth between first and last larger conical teeth in the external premaxillary tooth row; 75-78 lateral line scales ........................................................... A. boehlkei 2’.Horizontal scale rows around caudal peduncle 22-23; 7-9 small conical teeth between first and last larger conical teeth in the external premaxillary tooth row; 70-74 lateral line scales ............................................................................... 3 3. Branched anal-fin rays 25-27; 7-8 developed gill-rakers on first branchial arch; 22-29 small conical teeth in posterior dentary tooth row ........................................... A. maculosus 3’.Branched anal-fin rays 29-31; 5-6 developed gill-rakers on first branchial arch; 33-37 small conical teeth in posterior dentary tooth row ............................................ A. stigmatus 4. A triangular dark blotch on caudal base anteriorly continuous with dark longitudinal stripe approximately on midbody in freshly preserved specimens; 40-46 maxillary teeth ......... 5 4’.Dark blotch on caudal base absent or oblong, oval-shaped, anteriorly continuous with dark longitudinal stripe; 24-38 maxillary teeth ....................................................................... 6 5. Horizontal scale rows around caudal peduncle 20-22; 10-12 horizontal scale rows above lateral line, 10-12 below lateral line ......................................................................... A. sardina 5’.Horizontal scale rows around caudal peduncle 23-24; 13-14 horizontal scale rows above lateral line, 12-13 below lateral line ............................................................... A. nigrifasciatus 6. Caudal-fin base with few scattered dark chromatophores never forming a conspicuous dark blotch ....... A. pallidus 6’. Caudal-fin base with oblong dark blotch, conspicuous and continuous with longitudinal dark stripe on body .......... 7 7. Posterior dentary tooth row with 23-28 teeth; 8-11 small conical teeth in external tooth row on premaxilla; 9-11 inner dentary teeth ..................................................... A. anomalus 7’.Posterior dentary tooth row with 28-36 teeth; 6-8 small conical teeth in external tooth row on premaxilla; 10-13 inner dentary teeth .......................................................... A. acutus Acestrocephalus sardina (Fowler, 1913) Figs. 2-3 Charax sardina Fowler, 1913: 566, fig. 2 (type locality: Madeira River, about 200 miles east of W. long. 60º20’W, Brazil); Böhlke, 1984: 32 (catalog); Eschmeyer, 1998: 1507 (catalog). Cyrtocharax sardina; Fowler, 1950: 312 (listed). Cynopotamus (Acestrocephalus)sardina; Géry, 1972: 28 (diagnosis in key). Acestrocephalus sardina; Menezes, 1976: 39 (in part, only specimens from rio Aripuanã, MZUSP 10423); Eschmeyer, 1998: 1507 (catalog); Lucena & Menezes, 2003: 200 (in check list; maximum length, distribution). Acestrocephalus ginesi Lasso & Taphorn, 2000: 443 (type locality: Venezuela, Apure State, Río Cinaruco, playa en frente de Laguna Larga, Distrito Muñoz (06º33’45"N 67º24’W); holotype not seen; topotypes examined); Lucena & Menezes, 2003: 200 (in check list; maximum length; distribution); Lasso, Lew, Taphorn, Nascimiento, Lasso-Alcalá & Machado-Allison, 2004: 148 (listed). Acestrocephalus cf. ginesi; Lima et al., 2005: 166 (description; habitat; feeding habits; fisheries). Material examined. ANSP 39307, holotype, 31.4 mm SL, (data taken by H.A. Britski; digital image and radiographs examined), Brazil, Mato Grosso: rio Madeira system, by Edgar A. Smith, 1912; MZUSP 10423, 1, 89 mm SL, Aripuanã: rio Aripuanã, 9º34’S 59º25’W; MZUSP 60396, 1, 94 mm SL, rio Aripuanã, Porto de Balsa on the road between Colmiza and Panela, 10º09’S 67º27’W. MZUSP 29237, 11, 49-65 mm SL, Amazonas: ilha de Tamaquaré, rio Negro; MZUSP 29239 and 29241, 36, 50-71 mm SL, Marauiá: rio Negro; MZUSP 29240, 5, 51-66 mm SL, Massarabi: rio Negro; MZUSP 31140, 1, 84 mm SL, Cachoeira de São Gabriel: rio Negro; MZUSP 29238 and 31036, 6, 47.5-86 mm SL, Paraná do Jacaré: rio Negro. MZUSP 81209 and 81259, 4, 81-94 mm SL, rio Tiquié, indian village of Cururu, 0º16’N 69º54’W . MZUSP 56558, 2, 62 and 65 mm SL, rio Jutaí, 2º57’S 67º0’W; MZUSP 35498, 3, 52-69 mm SL,Venezuela, Apure: Río Orinoco system, 1º55’N 67º04’W. MZUSP 35499, 5, 53.7-82.6 mm SL, Rio Negro: Río Negro, near San Carlos do Rio Negro. Diagnosis. Acestrocephalus sardina is most similar to A. nigrifasciatus, both having identical color patterns consisting of a triangular dark blotch on caudal-fin base, anteriorly continuous with a longitudinal dark stripe extending along lateral line (Figs. 3 and 12) not found in any other species of the genus. In addition, both have the eye diameter greater than their congeners (Fig. 4). Acestrocephalus sardina can be distinguished from A. nigrifasciatus by having fewer horizontal scale rows above lateral line (10-12 vs 13-14) and below (10-12 vs 12-13). See Tables 1 and 2. Acestrocephalus nigrifasciatus also has the muscular hiatus over the anterior part of the swim bladder which is longer than and narrower than A. sardina and the fibers of the obliquus inferioris muscle, visible in the latter are entirely covered by the obliquus superioris muscle in the former (compare Figs. 5a and 5e). Description. Morphometrics of holotype and additional specimens presented in Table 3. Meristic and morphometric data based on all lots for this species because no statistical Table 1. Frequency distribution of scales above lateral line in the species of Acestrocephalus. Scales above lateral line 10 11 12 13 14 15 A. sardina 1 51 24 A. boehlkei 12 6 3 A. pallidus 48 12 A. nigrifasciatus 7 5 A. acutus 5 40 1 A. stigmatus 4 2 A. maculosus 6 Description of five new species of Acestrocephalus 388 differences found among population samples studied, in spite of wide distribution of species. Body elongate, relatively large (SL= 31.4-90 mm), compressed and not very deep; greatest body depth between occiput and dorsal-fin origin near middle of pelvic-fin length. Dorsal body profile nearly straight, but inclined ventrally from snout tip to base of supraoccipital spine, slightly convex between that point and dorsal-fin origin, nearly straight along dorsal-fin base, and straight or nearly so from base of dorsal-fin termination to caudal peduncle. Ventral body profile convex from tip of lower jaw to anal-fin Table 2. Frequency distribution of scales below lateral line in the species of Acestrocephalus. Scales below lateral line 10 11 12 13 A. sardina 58 16 2 A. boehlkei 18 3 A. pallidus 5 55 A. nigrifasciatus 5 7 A. acutus 1 22 23 A. stigmatus 3 3 A. maculosus 6 Table 3. Morphometrics of Acestrocephalus sardina. Standard length is expressed in mm; measurements through head length are percentages of standard length; last four entries are percentages of head length. Specimens are from ANSP 39307 (holotype), MZUSP 29237-241, 31140, 31036, 81209, 35498, 35499, 60396, 10423, 56558. Characters Holotype N Range Mean SD Standard length 31.4 76 31.4-90.0 Body depth 26.1 66 24.9-30.8 28.0 1.2 Snout to dorsal-fin origin 49.0 76 48.2-50.3 50.1 0.9 Snout to pectoral-fin origin 31.2 76 28.6-33.4 30.4 1.2 Snout to pelvic-fin origin 42.0 76 40.4-45.6 43.0 1.2 Snout to anal-fin origin 57.3 76 56.1-62.7 58.9 1.5 Caudal peduncle depth 8.6 76 6.1-8.6 7.9 0.3 Caudal peduncle length 10.8 76 9.2-12.6 10.7 0.8 Pectoral-fin length 17.5 76 16.2-19.4 17.6 0.6 Pelvic-fin length 16.8 76 13.1-17.8 15.5 0.9 Dorsal-fin base length 11.1 76 11.0-14.3 12.7 0.6 Dorsal-fin height 27.4 76 22.7-28.0 25.1 1.1 Anal-fin base length 37.2 76 31.4-37.3 34.0 1.0 Anal-fin lobe length 20.0 76 16.3-21.8 18.3 1.1 Eye to dorsal-fin origin 35.0 76 31.7-36.0 33.2 0.8 Dorsal-fin origin to caudal-fin base 52.2 76 49.5-54.3 51.8 0.9 Head length 30.2 76 30.1-33.3 31.8 0.7 Horizontal eye diameter 31.5 76 31.3-37.4 34.4 1.2 Snout length 28.4 76 26.0-31.5 28.0 0.9 Least interorbital width 21.0 76 16.6-21.4 19.3 1.0 Upper jaw length 67.3 76 62.4-69.1 65.2 1.4 Fig. 3. Acestrocephalus sardina, MZUSP 81209, 93 mm SL, immature female, rio Tiquié, rio Negro drainage. Fig. 4. Scatter plot of eye diameter on head length for specimens of Acestrocephalus sardina, A. boehlkei, A. pallidus, A. nigrifasciatus and A. acutus. Acestrocephalus sardina and A. nigrifiasciatus have larger eye diameters than the other species suggesting the recognition of two species groups with respect to this character (see diagnoses of A. sardina and A. nigrifasciatus). 2 3 4 5 6 7 8 9 10 11 818283848 Head Length - mm Eye Diameter - mm A . sardina A . boehlkei A . pallidus A . nigrifasciatus A . acutus N. A. Menezes 389 origin, nearly straight and dorsally inclined along anal-fin base and slightly concave from base of posterior most analfin ray to origin of procurrent caudal-fin rays. Snout pointed. Lower jaw included in upper jaw when mouth is fully closed. Mouth angled posteroventrally from anterior tip of snout to posterior part of mandibular joint. Maxilla extending slightly beyond vertical line passing through posterior border of orbit. Dorsal-fin rays ii,9 in all specimens, n=76, including holotype. Posterior most ray unbranched, n=76. Adipose fin present. Anal-fin rays iv,32 (iv or v, usually iv unbranched, branched rays mean=30.3, range 28-33, n=76, posterior ray split to its base and counted as 1). Moderately developed anterior anal-fin lobe including anterior unbranched rays and first 7-8 branched rays. No hooks on anterior rays of males, Fig. 5. Schematic drawings of external view of muscles covering the anterior portion of the swim bladder in A – Acestrocephalus sardina (MZUSP 29241); B – A. boehlkei (MZUSP 38699); C – A. maculosus (MNRJ 12657); D – A. stigmatus (MZUSP 10422); E – A. nigrifasciatus (MCP 30420); F – A. acutus (MNRJ 17612); G – A. pallidus (MZUSP 73471). Anterior towards left; 1 plr (first pleural rib); 2 plr (second pleural rib); os (obliquus superioris); ls (lateralis superficialis); oi (obliquus inferioris). Not drawn to scale. Fig. 6. Scatter plot of number of maxillary teeth on standard length for specimens of Acestrocephalus sardina, A. boehlkei. Acestrocephalus nigrifasciatus, A. pallidus, and A. acutus. The figure is not intended to show species differences therefore regression lines were not drawn and regression analyses were not performed. The primary purpose is to express the tendencies of the number of teeth on the maxilla to increase according to an increase in standard length. For the species represented by large number of specimens the data points are widely scattered. Fig. 7. Scatter plot of number of posterior dentary teeth for specimens of Acestrocephalus sardina,A. boehlkei,A. pallidus,A. nigrifasciatus, and A. acutus. The figure is not intended to show species differences therefore regression lines are not drawn and regression analyses were not performed. The primary purpose is to express the tendencies of the number of teeth on the posterior row on the dentary to increase according to an increase in standard length. For the species represented by large number of specimens the data points are widely scattered. 27 32 37 42 47 52 57 20 40 60 80 100 120 140 Standard Length - mm Number of Maxillary Teeth A . sardina A . boehlkei A .pallidus A . nigrifasciatus A . acutus 17 22 27 32 37 42 20 40 60 80 100 120 140 Standard Length - mm Number of Posterior Dentary Teeth A . sardina A . boehlkei A . pallidus A . nigrifasciatus A . acutus Description of five new species of Acestrocephalus 390 but very few sexually mature males represented in examined sample. Pectoral-fin rays i,13 (anterior unbranched ray i, n=76) branched rays mean=13.6, range 12-15, n=76. Posterior tips of longest pectoral-fin rays reaching slightly beyond pelvic-fin origin. Pelvic-fin rays i,7, n=76. No hooks on pelvic-fin rays of sexually mature males. Distal tips of longest pelvic-fin rays extending to or slightly beyond anterior border of anus. Principal caudal-fin ray count 10/9 in all specimens, n=76. Lateral line complete, perforated scales 73 (mean=71.3, range 67-74, n=76). Scale rows above lateral line 12 (mean=11.3, range 10-12, n=76). Scale rows below lateral line 10 (mean=10.3, range 10-12, n=76). Scale rows around caudal peduncle 20 (mean=20.7, range 20-22, n=76). Premaxilla with two slightly enlarged inner conical teeth, an outer row with one anterior canine followed by row of small conical teeth and one posterior canine. Anterior canine outside anterior border of lower jaw when mouth closed. Outer row small conical teeth 8 (mean=7.7, range 7-9, n=75). Maxillary teeth 44 (mean=43.6, range 40-53, n=75). Maxillary teeth conical with tendency to increase in number according to increase in standard length (Fig. 6). Dentary with outer row of conical teeth of which four anterior most spaced and first and third larger than third and fourth, these followed by posterior row of close-set smaller conical teeth that show tendency to increase in number with increase in standard length (Fig. 7). Posterior dentary teeth 28 (mean=29.4, range 26-33, n=75). Teeth in inner row on dentary conical, very small, slightly inclined proximally to four anterior spaced larger conical teeth of outer row. Inner row dentary teeth 9 (mean=9.8, range 7-12, n=75). Vertebrae 38 (mean=39, range 38-40, n=35). Total number of gill-rakers on first gill-arch 7 (mean=7, range 6-8, n=76). Muscular hiatus of pseudotympanum (Fig. 5a) relatively large, dorsally limited by lateralis superficialis muscle, posteriorly by large exposed portion of second pleural rib, anteriorly by small exposed portion of first pleural rib, anteroventrally by large portion of the obliquus superioris and posteroventrally by small portion of obliquus inferioris muscle. Small opening anterior to first pleural rib visible. Color in alcohol. Body pale to dark yellow, slightly darker dorsally than ventrally due to presence of dark chromatophores. Dark chromatophores on dorsal and lateral parts of trunk mostly concentrated along free border of scales. Dorsal part of head from tip of snout to supraoccipital region darker than remaining dorsal surface of body. Premaxilla, median part of maxilla and lower jaw densely pigmented with dark chromatophores. Scattered dark chromatophores on infraorbital and opercular bones. Lateral dark body stripe extending from upper opercle to caudal peduncle where fused with triangular dark blotch on caudal base, dark color extending to base of principal caudal rays. Lateral body stripe narrower anteriorly and posteriorly and sometimes obscured by guanine. Anterior part of lower jaw bordered with dark pigmentation. Mental area of lower jaw with diffuse dark blotch in some specimens. Dorsal-fin origin with black dot extending to base of first unbranched dorsal-fin ray. Pectoral, pelvic, dorsal, and caudal fins pale, with few scattered dark chromatophores. Distribution. This species is known from tributaries of the rio Madeira, Mato Grosso, rio Jutaí and rio Negro, Amazonas, Brazil and of the Orinoco Basin, Venezuela (Fig. 8). Remarks. Menezes’ redescription of A. sardina (1976) was based on the examination of two specimens, one of them from rio das Mortes near Xavantina, Mato Grosso. It was mentioned that no differences had been found among them and a small dark blotch at the humeral region was described for the species. Actually, this spot is present only in the specimen from rio das Mortes considered to belong to A. stigmatus herein described. A dark humeral spot is never present in specimens of A. sardina. At that time it was predicted that the taxonomic status of A. sardina would be cleared up only after a study based on a large series of specimens. Acestrocephalus ginesi Lasso & Taphorn is herein considered a junior synonym of A. sardina. Five paraypes from Río Negro, near San Carlos de Río Negro, Venezuela (MZUSP 53499) and three specimens collected in the Apure State, near the type locality were studied and proved to be morphologically indistinguishable from specimens of the population samples representing A. sardina. Acestrocephalus boehlkei Menezes, 1977 Fig. 9 Acestrocephalus boehlkei Menezes, 1977: 186, fig. 1 (original description, type locality: Río Punino, tributary of Río Payamino (Napo River system), above Coca, Ecuador). Material examined. MCZ 51473, holotype, 135 mm SL (radiograph examined), Ecuador: Río Punino, tributary of Río Payamino, Río Napo system, by T. Roberts and Parker, 25-27 November 1971; MZUSP 12993-94, 2, paratypes 85-116 mm SL, taken with holotype; MZUSP 12995, 1 paratype, 40 mm SL, Río Payamino and tributary 3-4 miles upriver from mouth of Río Payamino into Coca, by T. Roberts, Garcia, Parker and Herrera, 20 November Fig. 8. Map of northern and central South America showing the geographic distribution of the species of Acestrocephalus. Some symbols may represent more than one locality. N. A. Menezes 391 1971; MZUSP 38699, 2, 76-87.5 mm SL, Napo: Río Aguarico in Quarumo, Río Napo system, 0º1’S, 76º37.5’W. MZUSP 1299698, 3, paratypes, 59-85 mm SL, Peru, Huanuco: backwater near Pueblo Novo flowing into Río Tulumayo, by Catherwood Expedition, 27 September 1955. Diagnosis. Acestrocephalus boehlkei,A. maculosus sp.n. and A stigmatus sp.n. are the only species of the genus bearing a dark spot at the humeral region (Figs. 9, 10, and 11). Acestrocephalus boehlkei, however, has more anal-fin rays (34-36) than A. maculosus (25-27) and A. stigmatus (29-31) and more scale rows around caudal peduncle (25) than A. maculosus (23) and A. stigmatus (22-23). See tables 4 and 5. Additionally, A. boehlkei differs at once from A. maculosus and A. stigmatus in number of perforated lateral line scales (74-78 vs 70-73 in A. stigmatus and 71-73 in A. maculosus) and in number of small conical teeth between anterior and posterior canines of outer row premaxillary teeth(10-12 vs 7-9 in both A. stigmatus and A. maculosus (see Tables 6 and 7). The muscular hiatus of the pseudotympanum in A. boehlkei (Fig. 5b) is also wider than those of A. maculosus (Fig. 5c) and A. stigmatus (Fig. 5d). Description. Morphometrics of holotype and additional specimens presented in table 8. Meristic and morphometric data based on all examined lots of this species because no statistical differences found among them. Body moderately large (SL=31.5-135.0 mm). Body form, dorsal and ventral body profiles, shape of snout and mouth and extension of maxilla as in A. sardina. Dorsal-fin rays ii,9 in all specimens, n=21, including holotype. Posterior most ray unbranched, n =21. Adipose fin present. Anal-fin rays v,34 (iv or v, usually v unbranched, branched rays mean=34.5, range 33-36, n=21, posterior ray split to its base and counted as 1). Slightly developed anterior anal-fin lobe including anterior unbranched rays and first 9-10 branched rays. Anal fin of three sexually mature males with bilateral hooks on posterior part of anterior branched rays. In a specimen 87.5 mm SL (MZUSP 38699) hooks present on anterior 11 branched rays and number of hooks per ray vary considerably: first branched ray with 9, third with 17, sixth with 24 and eleventh with 8. Pectoral-fin rays i,14 (anterior branched ray i in all specimens, n=21), branched rays mean 14.6, range13-16, n=21. Posterior tips of longest pectoral-fin rays reaching beyond pelvic-fin origin. Pelvic-fin rays i,7, n=21. No hooks on pelvic-fin rays of sexually mature males. Distal tips of longest pelvic-fin rays extending to or slightly beyond posterior border of anus, but not reaching anal-fin origin. Principal caudal-fin ray count 10/9, n=21. Lateral line complete, perforated scales 74 (mean=76.1, range 74-79, n=21). Scale rows above lateral line 13 (mean=13.5, range 13-15, n=21). Scale rows below lateral line 12 (mean=12.1, range 12-13, n=21). Scale rows around caudal peduncle 25 in all specimens, n=9. Shape, size and arrangement of teeth on premaxilla, maxilla and dentary as in A. sardina. Outer row small conical teeth on premaxilla 12 (mean=10.1, range 9-12, n=21. Maxillary teeth 44 (mean=37.6, range 32-44, n=21), increasing in number according to increase in standard length (Fig. 6). Posterior row dentary teeth 33 (mean=26.3, range 20-33, n=21), increasing in number ontogenetically (Fig.7). Inner row dentary teeth 11 (mean=12, range 10-14, n=21). Vertebrae 39 (mean=39.6, range 39-41, n=9). Total number of gill-rakers on first gill-arch 6 (mean=6.1, range 6-8, n=21). Arrangement of muscles limiting muscular hiatus of pseudotympanum and degree of exposition of first and second pleural ribs as in A. sardina (compare figs. 5a and 5b). Color in alcohol. Body light brown to pale yellowish, darker dorsally. Dorsal head and snout more densely pigmented with dark chromatophores compared to lateral part of head. Lateral body stripe broader from below dorsal-fin origin to below adipose-fin origin, narrower from dorsal-fin origin anteriorly Table 4. Frequency distribution of branched anal-fin rays in the species of Acestrocephalus. Branched anal-fin rays 25 26 27 28 29 30 31 32 33 34 35 36 A. sardina 2 13 32 19 8 2 A. boehlkei 2 1 11 5 2 A. pallidus 11 14 26 8 1 A. nigrifasciatus 1 4 4 1 1 A. acutus 1 2 7 20 5 6 1 A. stigmatus 2 2 2 A. maculosus 1 1 4 Table 5. Frequency distribution of scales around caudal peduncle in the species of Acestrocephalus. Scales around caudal peduncle 20 21 22 23 24 25 A. sardina 25 47 3 A. boehlkei 9 A. pallidus 31 25 4 A. nigrifasciatus 10 2 A. acutus 15 25 6 A. stigmatus 3 3 A. maculosus 6 Lateral line scales 67 68 69 70 71 72 73 74 75 76 77 78 A. sardina 1 4 4 14 14 19 17 2 A. boehlkei 3 5 5 3 5 A. pallidus 1 1 12 14 15 14 3 A. nigrifasciatus 2 1 2 4 1 2 A. acutus 3 3 2 6 15 14 1 2 A. stigmatus 1 1 1 2 1 A. maculosus 1 1 4 Premaxillary teeth 6 7 8 9 10 11 12 A. sardina 26 43 4 A. boehlkei 7 1 A. pallidus 19 32 8 1 A. nigrifasciatus 1 7 4 A. acutus 1 4 23 A. stigmatus 3 2 1 A. maculosus 1 2 4 Table 6. Frequency distribution of lateral line scales in the species of Acestrocephalus. Table 7. Frequency distribution of premaxillary teeth in the species of Acestrocephalus. Description of five new species of Acestrocephalus 392 to upper opercle and on caudal peduncle, dark color sometimes obscured by guanine. Lateral stripe starts from behind upper opercle extending posteriorly to caudal-fin base where connecting to oblong dark blotch posteriorly extending to middle caudal-fin rays. Irregularly shaped, vertically elongated dark blotch at humeral region over anterior lateral body stripe, vertically above anterior pectoral fin. Mental area of lower jaw with diffuse dark blotch, sometimes unconspicuous or even absent. Small black dot at origin of dorsal-fin origin, extending to first unbranched dorsal-fin ray base. Dorsal, anal, and caudal fin dusky with scattered dark chromatophores along fin rays and membranes. Pectoral and pelvic fins pale with fewer dark chromatophores than other fins. Distribution. Upper Amazon River basin in tributaries of Río Napo, Ecuador and of Río Putumayo, Peru (Fig. 8). Remarks. Lasso & Taphorn (1992) reported A.boehlkei from the Ventuari River, Apure River system, in the upper Río Orinoco, but emphasized that the record should be confirmed. Lasso et al. (2004), in referring to this record added that the specimens probably belong to A. ginesi Lasso & Taphorn (= A. sardina) or to a species not yet described. Lasso & Taphorn (2000) compared meristic data with specimens from the Río Ventuari to data taken from specimens of A. ginesi (= A. sardina) and suggested that the former have more branched anal-fin rays and lateral-line scales than the latter (35-38 vs 29-36 and 73-76vs 63-71 respectively). In two specimens (MZUSP 37268) from the Río Suripa, a tributary of Río Apure, Barinas, Venezuela, the number of anal-fin rays (36 and 37) and maxillary teeth (35 and 38) are outside the range of values for A. sardina (28-33 and 40-53 respectively) and differ from A. boehlkei by having more posterior dentary teeth (32 and 34 vs 20-33 in A.boehlkei) and fewer small conical teeth in the outer row on the premaxilla (8 and 9 vs 9-12 in A. boehlkei). This strongly suggests that the specimens from the Apure River system in Venezuela, tentatively identified as A. ginesi (= A. sardina) and A. boehlkei probably belong to an undescribed species. Fig. 9.Acestrocephalus boehlkei, MZUSP 12993, paratype, 85 mm SL, mature male, Río Punino, Río Napo drainage. Table 8. Morphometrics of Acestrocephalus boehlkei. Standard length is expressed in mm; measurements through head are percentages of standard length; last four entries are percentages of head length. Specimens are from: MCZ 51473 (holotype), 51474-75 (paratypes), ANSP 134500-501 (paratypes), MZUSP 12993-998 (paratypes), 38699 and USNM 216140-141 (paratypes). Characters Holotype N Range Mean SD Standard length 135.0 21 31.5-135.0 Body depth 29.2 21 24.2-30.1 26.7 1.7 Snout to dorsal-fin origin 52.2 21 48.5-53.5 51.5 1.3 Snout to pectoral-fin origin 27.1 9 26.7-29.2 28.1 1.0 Snout to pelvic-fin origin 42.4 9 39.5-43.0 41.5 1.2 Snout to anal-fin origin 57.7 21 53.0-59.1 56.5 1.5 Caudal peduncle depth 7.4 21 7.4-10.5 8.5 0.7 Caudal peduncle length 8 9.0-10.3 9.8 0.4 Pectoral-fin length 8 16.4-18.3 17.3 0.5 Pelvic-fin length 8 13.1-15.0 14.5 0.8 Dorsal-fin base length 8 10.0-12.9 11.5 1.0 Dorsal-fin height 23.0 9 22.8-25.4 24.0 1.1 Anal-fin base length 35.6 9 35.6-38.7 36.6 1.0 Anal-fin height 8 16.3-19.0 17.2 1.0 Eye to dorsal-fin origin 8 36.1-38.0 37.0 0.7 Dorsal-fin origin to caudal-fin base 49.8 9 48.8-51.4 50.2 1.0 Head length 29.6 21 29.0-31.7 30.0 0.7 Horizontal eye diameter 31.2 9 28.1-32.5 30.2 1.5 Snout length 28.7 9 25.7-29.2 28.0 1.0 Least interorbital width 17.0 9 17.0-20.3 18.7 1.1 Upper jaw length 65.0 9 62.7-67.0 65.4 1.9 Table 9. Frequency distribution of total number of gill rakers in the species of Acestrocephalus. Lower limb gill rakers 5 6 7 8 A. sardina 4 66 6 A. boehlkei 6 1 1 A. pallidus 37 23 A. nigrifasciatus 9 3 A. acutus 22 24 1 A. stigmatus 2 4 A. maculosus 3 3 N. A. Menezes 393 Acestrocephalus maculosus, new species Fig. 10 Holotype. MZUSP 53974, 79 mm SL, immature female, Brazil, Goiás: Minaçu, córrego Água Parada, tributary of rio do Peixe, Serra da Mesa, Miguel T. Rodrigues et al., May 1996. Paratypes. MZUSP 90162, 1, 72 mm SL, taken with holotype. MNRJ 12714, 1, 42.3 mm SL, Brazil, Goiás: Uruaçu, rio Palmeira, left bank tributary of rio Maranhão, upper rio Tocantins basin, G.W. Nunan and D.F. Moraes Jr., 17 October 1985; MNRJ 12657, 3, 44-62 mm SL, Niquelândia: rio do Peixe, right bank tributary of rio Maranhão, upper Tocantins basin, G.W. Nunan & D.F. Moraes Jr, 08 October 1985. Diagnosis.Acestrocephalus maculosus has a dark blotch at the humeral region, a character shared only with A. boehlkei and A. stigmatus. In the diagnosis of A. boehlkei the differences among these species are discussed. Acestrocephalus maculosus can be easily distinguished from A. stigmatus by the number of anal-fin rays (25-27 vs 29-31), and total number of gill-rakers (7-8 vs 5-6). See Tables 4 and 9. The general structure of the pseudotympanum of A. maculosus (Fig. 5c) is quite peculiar and different from that of A. stigmatus (Fig. 5d) and all the other species of Acestrocephalus examined (Figs. 5a, b, e, f and g). In A. maculosus the muscular hiatus is very reduced as the result of the great development of the obliquus superioris muscle covering the anterior portion of the swim bladder. As a consequence, the opening anterior to first pleural rib, this and the second pleural rib as well as the obliquus inferioris muscle are not visible. Description. Morphometrics of holotype and paratypes presented in table 10. Body relatively small (SL=42.3-79 mm). Body form, dorsal and ventral body profiles, shape of snout and mouth and extension of maxilla as in A. sardina. Dorsal-fin rays ii,9 in all specimens, n=6, including holotype. Posterior most ray unbranched, n=6. Adipose fin present. Anal-fin rays iv,27 (iv or v, usually iv unbranched, branched rays mean=26.5, range 25-27, n=6, posterior ray split to its base and counted as 1). Moderately developed anterior anal-fin lobe including anterior unbranched rays and first 6-7 branched rays. No hooks on anterior rays of two sexually mature males (MZUSP 90162, 92 mm SL and MNRJ 12657, 62 mm SL). Pectoral-fin rays i,14 (anterior branched ray i, n=6) branched rays mean=14, range 13-15, n=6. Posterior tips of longest pectoral-fin rays reaching scarcely beyond pelvic-fin origin. Pelvic-fin rays i,7, n=6. No hooks on pelvic–fin rays of sexually mature males. Distal tips of longest pelvic-fin rays extending slightly beyond posterior border of anus, falling Fig. 10.Acestrocephalus maculosus, MZUSP 53974, holotype, 79 mm SL, immature female, córrego Água Parada, rio Tocantins drainage. Table 10. Morphometrics of Acestrocephalus maculosus. Standard length is expressed in mm; measurements through head are percentages of standard length; last four entries are percentages of head length. Specimens are from: MZUSP 53974, 90162, MNRJ 12714, 12657. Characters Holotype N Range Mean SD Standard length 79.0 6 42.3-79.0 Body depth 29.7 6 27.2-29.7 28.4 1.3 Snout to dorsal-fin origin 54.4 6 52.7-55.5 54.4 0.9 Snout to pectoral-fin origin 31.6 6 31.3-32.1 31.4 0.1 Snout to pelvic-fin origin 46.3 6 45.4-46.3 46.0 0.6 Snout to anal-fin origin 61.0 6 59.3-61.4 60.3 0.8 Caudal peduncle depth 8.8 6 8.0-9.3 8.7 0.4 Caudal peduncle length 11.4 6 11.0-12.5 11.6 0.6 Pectoral-fin length 17.3 6 17.2-18.5 17.7 0.6 Pelvic-fin length 15.2 6 15.2-16.7 15.7 0.5 Dorsal-fin base length 12.4 6 11.3-12.5 12.0 0.4 Dorsal-fin height 25.3 6 24.3-26.2 25.1 1.6 Anal-fin base length 30.7 6 30.7-33.7 31.6 1.5 Anal-fin height 16.9 6 16.3-19.6 18.0 1.5 Eye to dorsal-fin origin 38.0 6 37.5-38.8 38.2 0.5 Dorsal-fin origin to caudal-fin base 50.0 6 47.7-51.3 49.5 1.3 Head length 33.0 6 31.5-33.1 32.7 0.9 Horizontal eye diameter 29.6 6 29.1-31.7 30.5 0.9 Snout length 28.0 6 27.7-28.8 28.2 0.2 Least interorbital width 19.2 6 19.2-21.0 19.8 0.6 Upper jaw length 65.4 6 63.5-66.4 65.0 0.9 Description of five new species of Acestrocephalus 400 teeth on premaxilla 9 (mean=7.8, range 7-10, n=60). Maxillary teeth 31 (mean=33.8, range 30-38, n=60), tending to increase in number with an increase in standard length (Fig.6). Posterior row dentary teeth 34 (mean=32.2, range 29-37, n=60), also tending to increase in number with an increase in standard length (Fig. 7). Inner row dentary teeth 9 (mean=10.8, range 913, n=60). Vertebrae 38 (mean=38.7, range 38-39, n=47). Total number of gill-rakers on first gill-arch 7 (mean=6.4, range 6-7, n=60). Shape of muscular hiatus of pseudotympanum, arrangement of associated muscles and remaining structures (Fig. 5g) as in A. sardina. Color in alcohol. Body pale yellow with no distinct dark spots or blotches. Scatered dark chromatophores present on dorsal head and snout and along free edge of scales on dorsal trunk being slightly darker than remaining parts of body. Dark chromatophores on caudal-fin base scattered, visible only using stereomicroscope, not forming a blotch. Dark spot at dorsalfin origin weak and dark color on lower jaw mental area sometimes diffuse. Lateral body stripe largely consisting of guanine pigment extending from posterior section dorsal opercle to caudal-fin base. All fins pale. Distribution. Known only from rio Madeira and rio Machado, a tributary of rio Madeira (Fig. 8). Etymology. The species name pallidus, adjective, from the Latin for pale is in reference to the overall body color of this species. Acknowledgments For providing radiographs and digital images of type specimens I am grateful to David Catania (California Academy of Sciences, San Francisco, USA), Mark Sabaj (The Academy of Natural Sciences of Philadelphia), and Karsten Hartel and Andrew Williston (Museum of Comparative Zoology, Harvard University, USA). Heraldo A. Britski (MZUSP) examined, took data and photographed the holotype of Acestrocephalus sardina. The photographs of fishes, drawings and radiographs of fish structures in this paper were prepared by Eduardo Gouveia Baena (MZUSP). Assistance in the use of statistical computer programs was provided by Alberto Akama and José Luís O. Birindelli (MZUSP). Flávio C.T. Lima (MZUSP) and Mônica Toledo PizaRagazzo (Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo) helped in many ways, read the manuscript and made useful comments. This paper also benefited from review by M.W. Littman (Field Museum of Natural History, Chicago, USA). Osvaldo T. Oyakawa (MZUSP), Paulo A. Buckup (MNRJ) and Carlos A.S. de Lucena and Zilda Margarete de Lucena (MCP) arranged for the loan of specimens and provided useful information. The distribution map is based on a map of South America prepared by Marilyn Weitzman. Collecting permits were issued by Instituto Brasileiro do Meio Ambiente e dos Recursos Naturais Renováveis – IBAMA (processo IBAMA 02027.007616/99-98). Some specimens used in this study were obtained using financial support from Conselho Nacional de Desenvolvimento Científico e Tecnológico – CNPq, through PRONEX Project 661058/19972 to the author. Literature Cited Böhlke, J. E. 1984. Catalog of the type specimens in the ichthyological collection of the Academy of Natural Sciences of Philadelphia. Special Publication, 14: 1-246. Eschmeyer, W. N. (ed). 1998. Catalog of Fishes. California Academy of Sciences, San Francisco, 2905 p. Fink, W. L. & S. H. Weitzman. 1974. The so called cheirodontin fishes of Central America with descriptions of two new species (Pisces: Characidae). Smithsonian Contributions to Zoology, 172: 1-46. Fowler, H. W. 1913. Fishes of the Madeira River, Brazil. Proceedings of the Academy of Natural Sciences of Philadelphia, 65(3): 517579. Fowler, H. W. 1950. Os peixes de água doce do Brasil (2ª entrega). Arquivos de Zoologia, São Paulo, 6: 205-404. Géry, J. 1972. Corrected and supplemented descriptions of certain characoid fishes described by Henry W. Fowler, with revisions of several of their genera. Studies on Neotropical Fauna and Environments, 7: 1-35. Lasso, C. A. & D. Taphorn. 2000. A new species of Acestrocephalus (Characiformes: Characidae) from Venezuela. Revista de Biologia Tropical, 48(2): 443-447. Lasso, C. A., D. Lew, D. Taphorn, C. Nascimiento, O. Lasso-Alcalá, F. Provenzano & A. Machado-Allison. 2004. Biodiversidade ictiológica continental de Venezuela. Parte 1. Lista de espécies y distribución por cuencas. Memória Fundación La Salle de Ciências Naturales, 159-160 (for 2003): 105-195. Lima, F. C. T., L. Ramos, T. Barreto, A. Cabalzar, G. Tenório, A. Barbosa, F. Tenório, A. S. Resende & M. Lopes. 2005. Peixes do Alto Tiquié. Ictiologia e conhecimentos dos Tuyuka e Tukano. Pp. 111-304. In: A. Cabalzar, (org.). Peixe e gente no alto rio Tiquié. São Paulo: Instituto Ambiental, 339 p. Lucena C. A. S. & N. A. Menezes. 2003. Subfamily Characinae. Pp. 200-208. In: R.E. Reis, S.O. Kullander & C.J. Ferraris (eds). Check list of freshwater fishes of South and Central America. Edipucrs, Porto Alegre, 729 p. Menezes, N. A. 1976. On the Cynopotaminae, a new subfamily of the Characidae (Osteichthyes, Ostariophysi, Characoidei). Arquivos de Zoologia, São Paulo, 28(10): 1-91. Menezes, N. A. 1977. Acestrocephalus boehlkei, a new and disjunct Cynopotamine from Ecuadorean and Peruvian Amazon (Osteichthyes, Ostariophysi, Characidae). Papéis Avulsos de Zoologia, São Paulo, 30(3): 185-193. Submitted July 2006 Accepted November 2006