Copeia 2009, No. 3, 446–452
Two New Species of Acestridium Haseman, 1911 (Loricariidae: Hypoptopomatinae) from the Rio Madeira Basin, Brazil Roberto E. Reis1 and Pablo Lehmann A.1 Acestridium gymnogaster and A. scutatum are described as new from small tributaries to the middle Rio Madeira, Amazonas, Brazil. Acestridium gymnogaster is most similar to A. discus from which it differs in the number of medial unpaired predorsal plates, the arrangement of chromatophores in predorsal area, and the absence of contact midventrally between the lateral abdominal plates. Acestridium scutatum is most similar to A. triplax from which it differs in having a longer snout and by the shape of the preanal plate. A key to the species of Acestridium is provided. Acestridium gymnogaster e Acestridium scutatum, espe´cies novas, sa ˜ o descritas de pequenos rios tributa´rios do me´dio Rio Madeira, Estado do Amazonas, Brasil. Acestridium gymnogaster e´ mais semelhante a` A. discus, de quem difere pelo nu ´ mero de placas ´ımpares me´dias pre´-dorsais, arranjo dos cromato ´ foros na a´rea pre´-dorsal, e a ause ˆ ncia de contato entre as placas laterais abdominais na linha media. Acestridium scutatum e´ mais semelhante a` A. triplax, de quem difere por ter o focinho mais longo e pela forma da placa pre´-anal. Uma chave para as espe´cies de Acestridium e´ apresentada.
A
CESTRIDIUM has been known since the description of A. discus by Haseman (1911) almost a century ago based on specimens that originated in the Igarape´ da Cachoeira Grande near Manaus. However, it was only in the last decade that we began to develop an understanding of the species-level diversity within this highly distinctive hypoptopomatine genus. Since 1999, four additional species were described: A. dichromum, A. martini, and A. colombiensis from the Rı´o Orinoco basin in Venezuela and Colombia, and A. triplax from the lower Rio Amazonas. Sampling small tributaries to the Rio Madeira along the Trans-Amazonica road, east of Humaita´, Amazonas, Brazil, we discovered two additional species of Acestridium that we describe herein. We also provide a key to the species of Acestridium. MATERIALS AND METHODS The morphometric variables were measured with digital calipers (0.1 mm precision) and follow Rodriguez and Reis (2007). Proportional ranges presented in couplet 4 of key are from Retzer (2005). Names and counts of lateral, abdominal, and rostral plates follow Schaefer (1997). Prenuchal plate definition follows Rodriguez and Reis (2007). Specimens were cleared and stained (CS) for bone and cartilage according to the procedures of Taylor and Van Dyke (1985). In the lists of material examined, museum abbreviations and catalog numbers are presented first, followed by the number of specimens examined, number of cleared-andstained specimens, size range of specimens, and locality information. Accounts of new species also include number and size range of specimens measured for the morphometric comparisons, and date of collection and collectors. Institutional abbreviations follow Leviton et al. (1985). Acestridium gymnogaster, new species Figure 1, Table 1
Holotype.—MCP 43199, 59.1 mm SL, female, Brazil, Amazonas, Municı´pio de Humaita´, Rio Traira, approximately 35 km E of Rio Madeira on Trans-Amazonica road, 1
7u359330S, 62u449450W, 27 July 2004, R. E. Reis, F. Langeani, E. H. L. Pereira, and A. R. Cardoso. Paratypes.—Brazil, Amazonas, Humaita´: MCP 37784, 12+2 CS, 25.2–61.8 mm SL, 3, 40.2–61.8 mm SL, same data as holotype. MCP 37783, 10, 27.9–60.1 mm SL, 6, 38.0– 60.1 mm SL, MNRJ 32558, 2, 41.6–42.4 mm SL, creek ca 68 km E of Rio Madeira on Trans-Amazonica road, 7u439580S, 62u299400W, 27 July 2004, R. E. Reis, F. Langeani, E. H. L. Pereira, and A. R. Cardoso. MCP 37786, 1, 43.9 mm SL, ANSP 189026, 2, 39.9–44.4 mm SL, Rio Maici-mirim, ca 45 km E of Rio Madeira on Trans-Amazonica road, 7u379560S, 62u399440W, 27 July 2004, R. E. Reis, F. Langeani, E. H. L. Pereira, and A. R. Cardoso. Diagnosis.—Acestridium gymnogaster differs from all remaining Acestridium species except for A. discus in having three or four medial unpaired predorsal plates (one nuchal and two or three prenuchal plates), versus two median unpaired predorsal plates (one nuchal and one prenuchal plate). Acestridium gymnogaster is distinguished from A. discus by having two or three (usually three) prenuchal plates anterior to the nuchal plate (versus two or three, but usually two), in having chromatophores arranged in lines between the aligned odontodes of predorsal area (versus chromatophores concentrated in skin around the predorsal plates, giving a reticulated appearance to the predorsal area), by having the lateral abdominal plates extending to midventral line only posteriorly and always leaving a naked midventral area anteriorly (versus lateral abdominal plates extending to midventral line from the pectoral bridge to the preanal plate), and in possessing a nasal plate short, not reaching the anterior margin of the lateral ethmoid (versus nasal plate long and reaching the anterior margin of the lateral ethmoid). Acestridium gymnogaster is further distinguished from A. colombiensis and A. martini by having 12 branched caudal-fin rays (versus 10), the first bilateral postrostral plates not contacting each other midventrally (versus plates contacting each other midventrally), possessing one or two paired predorsal plates anterior to the prenuchal plates (versus four or five), and possessing a connecting bone present (versus absent). Acestri-
Laborato´rio de Sistema´tica de Vertebrados, Pontifı´cia Universidade Cato´lica do Rio Grande do Sul, P.O. Box 1429, 90619-900 Porto Alegre, RS, Brazil; E-mail: (RER)
[email protected]; and (PLA)
[email protected]. Send reprint requests to RER. Submitted: 26 August 2008. Accepted: 30 January 2009. Associate Editor: C. J. Ferraris. DOI: 10.1643/CI-08-150 F 2009 by the American Society of Ichthyologists and Herpetologists
Reis and Lehmann—Two new species of Acestridium
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Fig. 1. Acestridium gymnogaster, MCP 43199, holotype, 59.1 mm SL, female, Rio Traira, ca 35 km E of Rio Madeira on Trans-Amazonica road, 7u359330S, 62u449450W, Humaita´, Amazonas, Brazil.
dium gymnogaster is further distinguished from A. dichromum by having 12 branched caudal-fin rays (versus 11) and by lacking serrations on the inner margin of the pectoral-fin spine (versus conspicuous serrations present). Finally, A. gymnogaster is distinguished from A. scutatum and A. triplax by lacking a midventral series of plates between the lateral abdominal plates (versus abdomen with a middle series of plates). Description.—Morphometric data given in Table 1. Head, trunk, and caudal peduncle depressed, elongate, and narrow. Body width 6.0–6.6% of standard length. Dorsal profile of head and body straight or slightly concave from snout tip to eye, straight or slightly convex from eye to origin of dorsal fin, straight from last dorsal-fin ray to penultimate plate of caudal peduncle. Body covered with bony plates except for ventral part of head, midventral portion of abdomen between lateral abdominal plates, and very narrow area surrounding pelvicfin base and anus. Body plates uniformly covered by small odontodes arranged in longitudinal rows. Predorsal area with two paired plates followed by three median prenuchal plates (but one specimen with two and other with four prenuchal plates) and one nuchal plate anterior to dorsal fin. Connecting bone present, linking distal portion of first rib to anteriormost prenuchal plate. Postdorsal plates 15 (one specimen with 14, n 5 12). Postanal plates 14 or 15 (mean 5 14.5, n 5 12). Four lateral series of plates, mid-dorsal series absent. Parietosupraoccipital bone and predorsal plates with keels formed by ridges of aligned odontodes. Profile of head acutely triangular from dorsal view, with ovate spatulate projection on tip of snout. Spatulate projection formed by anterior portion of rostral plates and bearing large odontodes. Tip of spatulate projection of snout with small naked area. Rostral plate short, spatulate projection approximately one-half length of rostral plate. Two postrostral plates on each side follow rostral plate. Anterior portions of first postrostral plates not contacting each other along ventral midline. Postrostral plates and cheek plate bent ventrally and
visible in ventral view. Cheek plate with canal continuous with canal in fifth infraorbital. Eye placed laterally, not visible from ventral view. Iris operculum present. Mouth rounded, with globular papillae on both upper and lower lips. Maxillary barbel shorter than eye diameter. Premaxilla with ten to 18 (mean 5 13.5, n 5 12) bilobed teeth in functional series. Dentary with nine to 14 (mean 5 11.4, n 5 12) bilobed teeth in functional series. All teeth with uneven cusps, with reddishbrown tip. Mesial cusp longer and wider than lateral one. Abdomen with naked area anteriorly between lateral abdominal plates. Naked area also present between pectoral girdle and first pair of lateral abdominal plates. Three to five (mean 5 3.5, n 5 12) lateral abdominal plates on each side. Preanal plate roughly triangular, more acute anteriorly and wider posteriorly. Dorsal-fin rays i,7. Distal margin of dorsal fin straight or slightly convex, with first or second branched ray longest. Tip of depressed dorsal fin reaching third plate posterior to fin base. Dorsal-fin spinelet absent. Pectoral-fin rays I,6. Pectoral spine without serrae on inner margin. Ossified portion of spine reaching beyond middle of first branched ray. Distal margin of pectoral fin convex, with longest rays (first or second branched ray) falling short of pelvic-fin origin. Pelvicfin rays i,5. Unbranched ray very thick with enlarged odontodes turned mesially. Distal margin of pelvic fin convex. Second, third, or fourth branched pelvic-fin ray longest, reaching approximately one-half distance to anal-fin origin. Anal-fin rays i,5. Unbranched anal-fin ray reaching about four-fifths of length of first branched ray. Posterior margin of anal fin rounded, with first, second, or third branched ray longest. Tip of depressed anal fin reaching third plate posterior to fin base. Two or three plates along anal-fin base. Posterior margin of caudal fin truncate or slightly concave. Principal caudal-fin rays i,12,i. Adipose fin absent. Color in alcohol.—Dorsum light brown with thin stripes of dark pigmentation running between longitudinal rows of odontodes. Dark brown stripe running from snout along
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Table 1. Morphometrics of Holotype and Paratypes of Acestridium gymnogaster (n 5 12) and Acestridium scutatum (n 5 10). Values are given as percents of standard length or head length. SD 5 standard deviation, Holo 5 holotype.
Acestridium gymnogaster
Acestridium scutatum
Holo
Min
Max
Mean
SD
Holo
Min
Max
Mean
SD
Standard length (mm) Percent of standard length
59.1
38.0
61.8
47.0
—
62.7
36.4
62.7
40.9
—
Predorsal length
51.1
47.8
51.1
48.9
0.90
46.3
46.3
49.6
47.5
0.97
Postdorsal length
44.0
44.0
47.7
45.9
0.91
45.2
44.8
48.1
46.7
1.09
Postanal length
42.6
42.6
46.9
44.4
1.23
46.1
44.2
47.4
45.6
1.01
Body width at dorsal-fin origin
6.4
6.0
6.6
6.3
0.17
6.5
5.9
7.1
6.5
0.35
Body depth at dorsal-fin origin
5.4
4.5
5.8
5.2
0.38
4.5
4.5
5.5
4.9
0.28
Body width at anal-fin origin
6.1
5.4
6.2
5.8
0.26
6.1
5.7
6.6
6.0
0.27
Body depth at anal-fin origin
4.6
4.2
5.3
4.7
0.28
3.8
3.8
4.9
4.5
0.31
Preventral length
40.1
35.8
40.1
38.9
1.22
38.6
38.6
41.2
39.9
0.86
Supraoccipital-dorsal fin distance
18.1
13.9
18.1
16.1
1.28
15.1
12.1
15.2
13.2
0.96
Minimum depth of caudal peduncle
1.0
0.8
1.3
1.1
0.15
0.8
0.8
1.1
1.0
0.08
10.5
10.0
13.9
11.7
1.21
9.6
9.6
11.6
10.8
0.71
Length of pectoral-fin spine
8.5
8.2
10.2
9.0
0.68
8.1
7.7
9.7
8.6
0.75
Length of first pelvic-fin ray
5.7
5.5
7.2
6.4
0.52
5.1
5.1
5.9
5.6
0.28
Length of dorsal-fin spine
Length of first anal-fin ray
9.0
8.2
12.6
10.3
1.45
7.3
7.3
10.7
8.8
0.96
Snout tip to eye distance
22.2
19.6
22.9
21.6
0.89
21.7
21.5
23.5
22.4
0.69
Distance from pectoral-fin origin to pelvic-fin origin
10.6
9.2
10.8
10.3
0.58
10.7
9.5
11.1
10.5
0.53
Eye to dorsal-fin origin length
26.4
23.4
26.4
25.0
0.82
22.6
21.6
23.6
22.6
0.64
Oral disk width
6.4
5.5
8.2
7.0
1.01
5.3
5.3
7.0
6.3
0.46
Head length Percent of head length
33.2
30.9
34.1
33.0
1.14
30.8
30.8
35.3
34.1
1.33
Head depth
17.8
16.8
19.7
18.4
0.89
16.6
14.6
17.3
16.1
0.93
Head width
26.0
24.7
29.9
26.8
1.75
25.4
24.1
26.3
25.1
0.56
Interorbital width
17.8
15.3
19.4
17.9
1.10
15.5
14.8
17.3
16.0
0.83
Length of lower armored snout
18.9
11.4
25.7
18.2
3.68
30.0
19.5
30.1
22.1
3.05
6.6
6.3
8.5
7.5
0.82
6.7
6.7
8.9
8.0
0.67
24.5
18.3
27.0
25.2
2.28
23.8
23.3
26.9
25.3
1.27
Maximum eye diameter Length of postorbital head
side of head through eye and onto body. Stripe becoming less distinct on body and indistinct after vertical through dorsal fin. Cheek light yellow ventral of longitudinal stripe. Ventral surface of body yellowish, with sparse dark pigmentation ventrally between anal and caudal fins. Snout brownish ventrally. All spines and unbranched rays except on caudal fin yellowish tan with round black spots distributed regularly and interradial membranes hyaline. Caudal-fin rays brown, with numerous darker spots sometimes forming one or two dark bands. Color in life.—Mostly grass green dorsally, with brown lateral stripe from snout to middle of body; light brown or yellowish tan ventrally (based on field observations). Distribution and habitat.—Only known from the typelocality and two other creeks near Humaita´, in the Rio Madeira drainage (Fig. 2). The three localities are shallow streams (0.5–1.5 m deep, 5–20 m wide), with a sandy
bottom, clear or slightly black water, moderate water current, and dense aquatic and marginal vegetation. Etymology.—The species epithet, gymnogaster, from the Greek gymnos, bare, naked, and gaster, belly, referring to the naked area of skin between the anterior lateral abdominal plates. A noun in apposition. Acestridium scutatum, new species Figure 3, Table 1 Holotype.—MCP 43198, 62.7 mm SL, female, Brazil, Amazonas, Municı´pio de Humaita´, Rio Traira, ca 35 km E of Rio Madeira on Trans-Amazon Road, 7u359330S, 62u449450W, 27 July 2004, R. E. Reis, F. Langeani, E. H. L. Pereira, and A. R. Cardoso. Paratypes.—Brazil, Amazonas, Humaita´: MCP 37785, 9+2 CS, 28.6–39.7 mm SL, 9, 37.1–39.7 mm SL, MNRJ 32557, 2,
Reis and Lehmann—Two new species of Acestridium
449
predorsal plates (one nuchal and one prenuchal plate), versus three or four medial unpaired predorsal plates (one nuchal and two or three prenuchal plates). Acestridium scutatum is further distinguished from A. colombiensis and A. martini by having 12 branched caudal-fin rays (versus 10), in having the first bilateral postrostral plates not contacting each other midventrally (versus plates articulating to each other midventrally), in possessing one or two paired predorsal plates anterior to the prenuchal plates (versus four or five paired predorsal plates), and in having the connecting bone present (versus absent). Acestridium scutatum is further distinguished from A. dichromum by having 12 branched caudal-fin rays (versus 11) and by lacking or having very delicate serrations on inner margin of the pectoral-fin spine (versus conspicuous serrations present). Fig. 2. Distribution of Acestridium gymnogaster (dot) and A. scutatum (triangle). Symbols represent more than one locality.
33.9–39.1 mm SL, ANSP 189025, 2, 34.2–39.0 mm SL, same data as holotype. Diagnosis.—Acestridium scutatum differs from all remaining Acestridium species except for A. triplax in having a middle series of abdominal plates between the lateral abdominal plates (versus abdomen without a middle series of plates). Acestridium scutatum is distinguished from A. triplax by having a long snout (distance from the snout tip to the posteroventral margin of the rostral plate 24.7–33.6% of head length), versus snout short (22.0– 24.5% of head length), and in having a preanal plate with well developed anterior and posterior lateral expansions (Fig. 4A), versus preanal plate with slightly developed anterior and posterior lateral expansions (Fig. 4B). Acestridium scutatum is further distinguished from A. gymnogaster and A. discus by having two median unpaired
Description.—Morphometric data given in Table 1. Head, trunk, and caudal peduncle depressed, elongate, and narrow. Body width 5.9–7.1% of standard length. Dorsal profile of head and body slightly concave from snout tip to eye, straight to supraoccipital tip and slightly convex from that point to origin of dorsal fin, straight from last dorsal-fin ray to penultimate plate of caudal peduncle. Body covered with bony plates except for ventral portion of head and narrow area surrounding pelvic-fin base and anus. Body plates uniformly covered by small odontodes arranged in longitudinal rows. Predorsal area with two paired plates followed by one median prenuchal plate and one nuchal plate located anterior to origin of dorsal fin. Connecting bone present, linking distal portion of first rib to prenuchal plate. Postdorsal plates 16 (one specimen with 15, n 5 10). Postanal plates 15 or 16 (mean 5 15.6, n 5 10). Four lateral series of plates, mid-dorsal series absent. Parietosupraoccipital bone and predorsal plates with keels formed by ridges of aligned odontodes.
Fig. 3. Acestridium scutatum, MCP 43198, holotype, 62.7 mm SL, female, Rio Traira, ca 35 km E of Rio Madeira on Trans-Amazonica road, 7u359330S, 62u449450W, Humaita´, Amazonas, Brazil.
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Fig. 4. Preanal plate of species of Acestridium: (A) A. scutatum, MCP 43198; and (B) A. triplax, MPEG 12467. Scale bar: 1 mm.
Profile of head acutely triangular from dorsal view, with ovate spatulate projection on tip of snout. Spatulate projection formed by anterior portion of rostral plates and bearing large odontodes. Tip of spatulate projection of snout with small naked area. Rostral plate long, spatulate projection approximately one-third length of rostral plate length. Two postrostral plates on each side follow rostral plate. Anterior portion of first postrostral plates not contacting each other along ventral midline. Postrostral plates and cheek plate bent ventrally and visible from ventral view, cheek plate with canal from fifth infraorbital. Eye placed laterally, not visible from ventral view. Iris operculum present. Mouth rounded, with globular papillae on both upper and lower lips. Maxillary barbel shorter than eye diameter. Premaxilla with 14 to 19 (mean 5 16.1, n 5 10) bilobed teeth in functional series. Dentary with 11 to 16 (mean 5 12.9, n 5 10) bilobed teeth in functional series. All teeth with uneven cusps, with reddish-brown tip. Mesial cusp longer and wider than lateral one. Abdomen fully plated except for region of pectoral girdle. One series of middle abdominal plates present between lateral abdominal plates. Four to six (mean 5 4.5, n 5 10) lateral abdominal plates on each side. Preanal plate wide and distinctly expanded laterally both anteriorly and posteriorly. Dorsal-fin rays i,7. Distal margin of dorsal fin straight or slightly convex, with first or second branched ray longest. Tip of depressed dorsal fin reaching third plate posterior to fin base. Dorsal-fin spinelet absent. Pectoral-fin rays I,6. Pectoral spine with delicate serrae on inner margin. Ossified portion of spine reaching beyond middle of first branched ray. Distal margin of pectoral fin convex, with first or second branched ray longest (but not reaching to pelvic-fin origin). Pelvic-fin rays i,5. Unbranched ray very thick with enlarged odontodes turned mesially. Posterior margin of pelvic fin convex. Second, third, or fourth branched pelvic-fin ray longest, reaching less than one-half distance to anal-fin origin. Anal-fin rays i,5. Unbranched anal-fin ray reaching about four-fifths length of first branched ray. Posterior margin of anal fin convex, with first, second, or third branched ray longest. Tip of depressed anal fin reaching third or fourth plate posterior to fin base. Two or three plates along anal-fin base. Posterior margin of caudal fin truncate or slightly concave. Principal caudal-fin rays i,12,i. Adipose fin absent.
Fig. 5. Predorsal region of species of Acestridium: (A) A. martini, MZUSP 74275; (B) A. scutatum, MCP 37785; and (C) A. gymnogaster, MCP 37784. CP 5 compound pterotic, NP 5 nuchal plate, PNP 5 prenuchal plates, PPP 5 paired predorsal plates, SOC 5 supraoccipital. Scale bar: 5 mm.
Color in alcohol.—Dorsum light brown with thin stripes of dark pigmentation running between longitudinal rows of odontodes. Inconspicuous brown stripe running from snout along side of head through eye, becoming less distinct as it reaches body and becoming indistinct at vertical through dorsal fin. Cheek light yellow ventral of longitudinal stripe. Ventral surface of body yellowish. Body with sparse dark pigmentation ventrally between anal and caudal fins. Snout brownish ventrally. All spines and unbranched rays except for caudal fin yellowish tan with round dark spots distributed regularly; interradial membranes hyaline. Caudal-fin rays brown, with numerous darker spots sometimes forming one or two dark bands. Color in life.—Mostly grass green dorsally, with brown lateral stripe from snout to middle of body; light brown or yellowish tan ventrally (based on field observations). Distribution and habitat.—Only known from the Rio Traira, a small river near Humaita´, in the Rio Madeira drainage (Fig. 2). The type-locality is a shallow stream (0.5–1.5 m deep, 5–20 m wide), with a sandy bottom, slightly black water, moderate water current, and dense aquatic and marginal vegetation. Etymology.—The species epithet, scutatum, from the Latim scutum, shield, plate, referring to the three series of abdominal plates present in the new species. An adjective. KEY TO THE SPECIES OF ACESTRIDIUM 1a.
Two median unpaired predorsal plates (one nuchal 3 and one prenuchal plate; Fig. 5A, B) Three or four median predorsal plates (one nuchal and two or three prenuchal plates; Fig. 5C) 2 Lateral abdominal plates extending to midventral line from pectoral bridge to preanal plate (Fig. 6A); two or three (usually two) prenuchal plates anterior to the nuchal plate; chromatophores concentrated in skin around predorsal plates, giving reticulated _____________________________
1b.
_______________
2a.
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Fig. 6. Abdominal plates of species of Acestridium: (A) A. discus, MZUSP 85322; (B) A. gymnogaster, MCP 37784; and (C) A. scutatum, MCP 43198. CL 5 cleithrum, CO 5 coracoid, LAP 5 lateral abdominal plate, MAP 5 middle abdominal plate, PAP 5 preanal plate. Scale bar: 5 mm.
aspect to predorsal area; nasal plate long, reaching anterior margin of lateral ethmoid A. discus Lateral abdominal plates extending to midventral line only posteriorly, always leaving naked area anteriorly (Fig. 6B); two or three (usually three) prenuchal plates anterior to nuchal plate (Fig. 5C); chromatophores not concentrated in skin around predorsal plates, but arranged in lines between aligned odontodes of predorsal area; nasal plate short, not reaching anterior margin of lateral ethmoid A. gymnogaster, new species Caudal fin with 11–12 branched rays; first bilateral postrostral plates not contacting each other midventrally (Fig. 7A, B); one or two paired predorsal plates anterior to prenuchal plates (Fig. 5B, C); connecting bone present 5 Caudal fin with 10 branched rays; first bilateral postrostral plates articulating to each other midventrally (Fig. 7C); four or five paired predorsal plates anterior to prenuchal plates (Fig. 5A); con4 necting bone absent Interorbital distance wide (25.0–29.0% of distance between eye and origin of dorsal fin and 10.6– 13.0% in postdorsal distance) A. colombiensis Interorbital distance narrow (17.0–24.0% of distance between eye and origin of dorsal fin and 7.0– 10.5% in postdorsal distance) A. martini Abdomen without series of plates between lateral abdominal plates (Fig. 6A, B); caudal fin with 11 branched rays; pectoral-fin spine with conspicuous serrations on inner margin A. dichromum Abdomen with a middle series of plates between the lateral abdominal plates (Fig. 6C); caudal fin with 12 branched rays; pectoral-fin spine without serrations or with very delicate serrations on inner margin 6 Snout long (distance from snout tip to posteroventral margin of rostral plate 24.7–33.6% of head length); preanal plate with well developed anterior and posterior lateral expansions (Fig. 4A) A. scutatum, new species Snout short (distance from snout tip to posteroventral margin of rostral plate 22.0–24.5% of head length); preanal plate with slightly developed anterior and posterior lateral expansions A. triplax (Fig. 4B) ________________
2b.
____________________________
3a.
_____________________________________________________
3b.
______________________________________________________________
4a.
____________
4b.
_______________________
5a.
_____________________
5b.
_________________________________________________________________________________________
6a.
________________________________
6b.
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Fig. 7. Spatulate projection of snout of species of Acestridium: (A) A. triplax, MCP 41746; (B) A. discus, MZUSP 85322; and (C) A. martini, MZUSP 74275. RP 5 rostral plates, PRP 5 postrostral plate. Scale bar: 1 mm.
MATERIAL EXAMINED Acestridium colombiensis: Venezuela, Amazonas: ANSP 165830, 1, 44.0 mm SL, Rı´o Matiyure, at Achaguas, 7u459N, 68u119W. Acestridium dichromum: Venezuela, Amazonas: ANSP 187061, 2+1 CS, Rı´o Sipapo, approximately 6 km upstream of Pendare´, 4u519N, 67u439W. ANSP 160692, 1, 40.8 mm SL, Rı´o Sipapo, 500 m upstream of Pendare´, 4u549N, 67u439W. ANSP 161494, 6+2 CS, 34.6–50.7 mm SL, outflow stream from series of morichales ca 5.0 km from mouth of Rı´o Pamoni, 2u489N, 65u539W. ANSP 187061, 2+1 CS, 32.2– 38.8 mm SL, Rı´o Sipapo, ca 6 km upstream of Pendare, 4u519N, 67u439W. MCP 35016, 3, 37.4–56.1 mm SL, Can ˜o Cucurito, ca 1 km upstream mouth of Rı´o Autana, 4u449N, 67u419W. FMNH 103326, 6 paratypes, 27.2–57.4 mm SL, Can ˜ o Cucurito, ca 1 km above mouth in Rı´o Autana, 4u439480N, 67u379120W. Acestridium discus: Brazil, Amazonas: FMNH 54339, holotype, 69.1 mm SL, FMNH 54340, 1 paratype, 52.1 mm SL, Igarape´ de Cachoeira Grande, near Manaus. MHNG 2575.61, 2, 31.2–39.7 mm SL, Rio Cuiuni, Rio Negro basin. MZUSP 85320, 7+2 CS, 26.8–56.6 mm SL, Igarape´ Barroso, tributary to Rio Preto da Eva on Francisco Mendes road, 2u449N, 59u389W. MZUSP 85321, 12+2 CS, 22.4–62.4 mm SL, bathing spot at Igarape´ do Manu, Rio Preto da Eva basin, 2u409N, 59u429W. MZUSP 85322, 9+1 CS, 16.3–64.5 mm SL, Igarape´ near Sitio Bom Jesus, km 13 of Francisca Mendes road Rio Preto da Eva basin, 2u459N, 59u379W. MZUSP 85323, 6+1 CS, 18.8–55.3 mm SL, Rio Preta da Eva, 15 km N of town of Rio Preto da Eva, 2u359N, 59u459W. MZUSP 88878, 6, 30.4–64.3 mm SL, bathing spot ca 2 km downstream of Rio Preto da Eva, 2u429420S, 59u419360W. MZUSP 88944, 7, 32.8–65.1 mm SL, MZUSP 88966, 4, 35.4–66.9 mm SL, creek tributary to Rio Preto da Eva, below bathing spot Encanto da Mata, 2u379100S, 59u449300W. MZUSP 88962, 15, 19.9–62.1 mm SL, Rio Preto da Eva, ca 4 km upstream of town, 2u409490S, 59u439150W. MZUSP 88986, 10, 17.0– 63.4 mm SL, creek on road from Rio Preto da Eva to Pousada do Paraı´so, 2u459340S, 59u399490W.
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Acestridium martini: Venezuela, Amazonas: ANSP 160701, 7+1 CS, 31.9–42.9 mm SL, Rı´o Sipapo, approximately 6 km upstream of Pendare´, 4u519N, 67u439W. ANSP 160644, 1, 40.8 mm SL, Rı´o Sipapo, backwater channel behind sandbar 6–7 km above Pendare´, 4u519N, 67u439W. ANSP 165831, 6, 43.3–62.8 mm SL, Can ˜ o Horeda, at border of Bolı´varAmazonas Territories, ca 68 km NE of Puerto Ayacucho, 6u089N, 67u229W. MCP 35015, 4+1 CS, 46.5–69.7 mm SL, Rı´o Sipapo, above Pendare´, 2u319N, 66u309W. Brazil, Amazonas: MHNG 2577.55, 4, 33.7–44.6 mm SL, Rio Arac¸a´, Rio Negro basin. MZUSP 26820, 3+1 CS, 46.6–48.2 mm SL, Rio Cuieiras, Rio Negro basin, 2u509S, 60u309W. MZUSP 61945, 4, 38.6–54.6 mm SL, Rio Aiuana ˜ , near Santa Isabel do Rio Negro (5Tapurucuava). MZUSP 74275, 6+1 CS, 41.6– 60.5 mm SL, Igarape´ Jarada´, tributary to Rio Cuieiras, ca 40 km upstream mouth. MZUSP 77945, 2, 54.4–54.9 mm SL, Rio Aiuana˜, tributary to Rio Negro. Acestridium triplax: Brazil, Para´: MPEG 13355, holotype, 55.5 mm SL, MCP 41745, 9+1 CS, 41.8–52.8 mm SL, MPEG 12461, 9, 28.9–50.4 mm SL, Juruti, Igarape´ Mutum, tributary to Rio Arua˜, lower Rio Tapajo´s basin, 2u369450S, 56u119370W. MPEG 12614, 8+2 CS, 41.0–53.5 mm SL, MCP 41746, 8+2 CS, 30.6–52,0 mm SL, same locality as holotype. MPEG 12468, 10, 34.1–53.3 mm SL, MPEG 12475, 7, 34.1– 52.3 mm SL, creek at 2u279540S, 56u009250W. ACKNOWLEDGMENTS Special thanks to the All Catfish Species Inventory (NSF-DEB #0315963), which financed the Transcontinental Catfish Expedition, during which all type material of the two new
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species were collected. PLA was financed by a doctoral fellowship from CNPq (process #190033/02-9). RER is partially financed by CNPq (process #303362/2007-3). LITERATURE CITED Haseman, J. D. 1911. Descriptions of some new species of fishes and miscellaneous notes on others obtained during the expedition of the Carnegie Museum to central South America. Annals of the Carnegie Museum 7:315–328. Leviton, A. E., R. H. Gibbs, Jr., E. Heal, and C. E. Dawson. 1985. Standards in herpetology and ichthyology: part I. Standard symbolic codes for institutional resource collections in herpetology and ichthyology. Copeia 1985:802–832. Retzer, M. E. 2005. Description of a new species of Acestridium (Siluriformes: Loricariidae) from Colombia. Zootaxa 972:1–6. Rodriguez, M. S., and R. E. Reis. 2007. A new species of Acestridium Haseman, 1911 (Loricariidae: Hypoptopomatinae) from the eastern Amazon basin, Brazil. Neotropical Ichthyology 5:429–434. Schaefer, S. A. 1997. The Neotropical cascudinhos: systematics and biogeography of the Otocinclus catfishes (Siluriformes: Loricariidae). Proceedings of the Academy of Natural Sciences of Philadelphia 148:1–120. Taylor, W. R., and G. C. Van Dyke. 1985. Revised procedures for staining and clearing small fishes and other vertebrates for bone and cartilage study. Cybium 9:107–119.
