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Description of a new species of sand-dwelling catfish of the genus Stenolicmus (Siluriformes; Trichomycteridae) WOLMAR BENJAMIN WOSIACKI1, DANIEL PIRES COUTINHO2 & LUCIANO FOGAÇA DE ASSIS MONTAG3 Museu Paraense Emílio Goeldi (MPEG), Av. Magalhães Barata, 376, CP 399, CEP 66040-170, Belém, PA, Brazil. E-mail:
[email protected]. 2 Programa de Pós-Graduação em Zoologia, UFPA/MPEG, Av. Magalhães Barata, 376, CP 399, CEP 66040-170, Belém, PA, Brazil. E-mail:
[email protected] 3 Universidade Federal do Pará/UFPA, Laboratório de Ecologia e Zoologia de Vertebrados – Ictiologia, Instituto de Ciências Biológicas, Rua Augusto Corrêa, 01 - Guamá. 66075-110 Belém, PA Brazil, CP 479. E-mail:
[email protected] 1
Abstract Stenolicmus ix, new species, is described from Igarapé Curuá, left tributary of the Rio Amazonas, Pará, Brazil. It can be distinguished from S. sarmientoi by the length of the nasal barbels that reach the base of the first opercular odontodes; length of the maxillary barbels that reach the posterior margin of the opercular odontode plate; seven well-developed opercular odontodes; seven well-developed interopercular odontodes; color pattern of the dorsal region of trunk composed of agglomerated chromatophores forming circular patches twice the diameter of the eye; proportionally large eyes, 11.8% HL; caudal peduncle tall, 11.6% SL, without dark bar at base of the caudal fin; length of the head proportionately larger, 17.9% SL; unbranched rays of caudal fin reaching distal margin of fin. Comparisons with other Sarcoglanidinae and Trichomycteridae are presented. Some comments on the systematics and phylogenetic relationships of the group are made. Key words: New catfish, Sarcoglanidinae, lower Amazon basin
Resumo Stenolicmus ix, nova espécie, é descrita do Igarapé Curuá, afluente da margem esquerda do Rio Amazonas, Pará, Brasil. A nova espécie é distinta de S. sarmientoi pelo comprimento dos barbilhões nasais atingindo a base dos odontódios operculares anteriores; comprimento dos barbilhões maxilares atingindo a margem posterior da placa de odontódios operculares; sete odontódios operculares bem desenvolvidos; sete odontódios interoperculares bem desenvolvidos; padrão de coloração da região dorsal do tronco composto cromatóforos aglomerados formando manchas circulares com diâmetro duas vezes o do olho; olhos proporcionalmente grandes, 11.8% HL; pedúnculo caudal elevado, 11.6% SL; sem barra escura na base da nadadeira caudal; comprimento da cabeça proporcionalmente maior, 17.9%SL; raios não ramificados da nadadeira caudal longos, atingindo a margem distal da nadadeira. São apresentadas comparações com demais Sarcoglanidinae bem como outros trichomycterídeos. Tópicos sobre a sistemática e filogenia do grupo são comentados.
Introduction The subfamily Sarcoglanidinae (Trichomycteridae) is a monophyletic group (Costa, 1994; de Pinna, 1998) composed of six genera, four of which are, currently, monospecific (Malacoglanis, Sarcoglanis, Stauroglanis and Stenolicmus). Ammoglanis possesses three valid species (Mattos et al. 2008; Costa, 1994; and de Pinna and Winemiller, 2000), and Microcambeva, two described species with two species recognized but still undescribed (Wosiacki and de Pinna, 2007). In Sarcoglanidinae, except for A. pulex de Pinna and Winemiller and Microcambeva ribeirae Costa, Lima and Bizerril, all other known species were described based on one to three specimens. The reduced number of Sarcoglanidinae specimens in collections can be, partially, explained by the limited access to
Accepted by M.R. de Carvalho: 21 Dec. 2010; published: ?? Month 2011
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the areas where the species occur and inadequate collectiing methods. Additionally, species of Sarcoglanidinae are difficult to find in nature due to their diaphanous condition, small body size and sand-dwelling behavior. Sarcoglanidinae have a wide distribution across the Amazon and Orinoco basins, and costal rivers of southeastern Brazil (Myers and Weitzman, 1966; de Pinna, 1989; Costa and Bockmann, 1994; Costa et al. 2004). The genus Stenolicmus was established to include S. sarmientoi de Pinna and Starnes, described based on three small specimens from the Mamoré hydrographic system (Departmento de Beni, Bolivia). De Pinna and Starnes (1990) assigned Stenolicmus to Sarcoglanidinae based on the presence of several synapomorphies shared with the remaining genera of the subfamily. Conversely, the relationship among the genera of Sarcoglanidinae remained uncertain until Costa and Bockmann (1994) contributed to our understanding of subfamilial relationships. In the same year, Costa (1994) described Ammoglanis and proposed a hypothesis of relationship for all genera of Sarcoglanidinae (Ammoglanis (Microcambeva (Stenolicmus (Stauroglanis (Malacoglanis Sarcoglanis))))) which is currently accepted. Therefore, considering the overall value for biodiversity studies as well as the extreme difficulty in obtaining specimens of Sarcoglanidinae, a new species of Stenolicmus is described based on a single specimen. The new species was collected during an ichthyological survey of the headwaters of the Rio Curuá in Pará State, Brazil, a remote region accessible only by helicopter.
Material and methods All measurements were taken with calipers, using the left side when necessary and with the aid of a stereoscopic microscope. Morphometric measurements and meristic counts follow Tchernavin (1944), with the modifications in de Pinna and Starnes (1990). Counts of the lateral line pores follow Bockmann and Sazima (2004). The illustration of the holotype was made, based on the photo, using Adobe Photoshop software.
Stenolicmus ix, new species Figs. 1–3; Tab. 1 Holotype: MPEG 15101, 19.0mm SL, Brazil, Pará State, Alenquer Municipality, unnamed igarapé tributary of Igarapé Curuá, tributary of the left margin of the Rio Amazonas, 0°9'47.6''S and 55º11'1.2''W, L. F. A. Montag, D. P. Coutinho and W. B. Mota. Diagnosis. Stenolicmus ix can be distinguished from S. sarmientoi by the length of the nasal barbels, reaching the base of the first opercular odontodes (vs. reaching anterior margin of eyes); length of maxillary barbels reaching posterior margin of opercular odontode plate (vs. reaching posterior margin of interopercular odontode plate); seven well-developed opercular odontodes (vs. six); seven well-developed interopercular odontodes (vs. five or six); pelvic fin rays, i+4 (vs. iv); color pattern of posterior region of trunk composed of agglomerated chromatophores forming circular patches twice the diameter of the eye (vs. without circular patches twice the diameter of the eye); large eyes with 11.8% HL (vs. 6%); caudal peduncle depth, 11.6% SL (vs. 8.5–9.5%); absence of dark bar at the base of the caudal fin (vs. presence of dark bar); head length, 17.9% SL (vs. 14.9–15.1%); and unbranched rays of caudal fin long, reaching distal margin of fin (vs. rays short, not reaching half the length of caudal fin). Description. Morphometric data are provided in Table 1. Overall shape of body similar to that of S. sarmientoi (see de Pinna and Starnes, 1990, Fig. 1). Body elongate, head wider than trunk in dorsal view. Body slightly depressed at pectoral-fin insertion, gradually taller and more compressed posteriorly. Caudal peduncle gently tapering to caudal fin. Dorsal profile of head straight, gently convex from occipital to dorsal-fin origin, concave at dorsal-fin base. Dorsal profile of caudal peduncle straight; low cutaneous fold from close to last dorsal-fin ray to continuous caudal fin base. Ventral profile of head convex, pectoral-fin girdle concave, body convex to anal-fin origin, anal-fin base concave. Ventral profile of caudal peduncle straight; low cutaneous fold from close of last dorsalfin ray to continuous caudal-fin base. Head small, depressed, less deep than body, its dorsal surface flat. Branchial membranes united to isthmus, gill openings not constricted. Eyes small but well-defined margins, with distinct lenses and covered by thin transparent integument, located dorsolaterally on head. Posterior naris round, with similar diameter of eyes, located midway
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between these and anterior naris, and surrounded only anteriorly by low rim of integument. Anterior naris surrounded by short tube of integument, continuous posterolaterally with nasal barbel. Mouth subterminal, upper jaw slightly longer than lower, corners only slightly curved posteriorly. Upper lip continuous with remainder of dorsal surface of head, its anterior border abruptly thinner, forming a narrow fold. Lower lip narrow, limited by rictal barbel bases, scattered papiles over surfaces, cutaneous fold as discreet lobes at corners. Snout with flat lateral expansion along area between eye and maxillary barbel base. TABLE 1. Morphometric data for holotype of Stenolicmus ix n. sp. Holotype mm Standard length
19.0
Total length
23.1
%
SL Body depth
3.2
16.8
Predosal length
12.8
67.4
Preanal length
13.1
68.9
Prepelvic length
10.5
55.3
Caudal peduncle depth
2.2
11.6
Caudal peduncle length
4.2
22.1
Head length
3.4
17.9
Pectoral-fin length
4.0
21.1
Pelvic-fin length
1.8
9.5
Dorsal-fin base length
1.9
10.0
Anal-fin base length
1.9
10.0
Head width
3.4
100.0
Interobital
0.9
26.5
Eye diameter
0.4
11.8
Maxillary barbel length
2.4
70.6
Nasal barbel length
2.0
58.8
Rictal barbel length
1.8
52.9
Breadth of mouth
1.4
41.2
HL
All barbels with visible internal cores and similar to each other in general aspect. When completely extended, maxillary barbel reaching posterior margin of opercular patch of odontodes, rictal barbel to posterior margin of interopercular patch of odontodes, and nasal barbel to posterior margin of opercular patch of odontodes. Maxillary barbel with very broad base, corresponding to enlarged maxilla, visible by transmitted light. Internal core of maxillary barbel thick and slightly darker than surrounding tissues, easily seen along whole length of barbel. Rictal barbel shortest, narrow, completely overlain and partly surrounded by base of maxillary barbel. Nasal barbel thinnest. Internal cores of rictal and nasal barbels obvious, but not as conspicuous as that of maxillary barbel. Opercular patch of odontodes large, roundish, with seven odontodes surrounded by fleshy rim of integument. Interopercular patch of odontodes roundish, slightly longer than deep, with seven odontodes surrounded by rim of integument. Pores po1-2 (postotic sensory pores 1 and 2) representing limits of latero-sensory system of skull. Lateral line nearly absent, pores ll1-2, lateral line sensory branches 1 (supracleithral sensory branch) and 2 represent a short oblique branch dorso-posterior to base of pectoral fin. Pectoral fin long, narrow, originating immediately posterior to posterior margin of branchial membrane, at vertical through posterior margin of opercular patch of odontodes; pectoral-fin rays i+4; first ray unbranched, seg-
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mented, longer, thicker, prolonged as a filament 1/3 of its length; remaining rays branching once, becoming gradually shorter, and thinner. Axillary gland small, restricted to area dorso-posterior to base of pectoral fin, its small pore located immediately dorsal to pectoral-fin base.Pelvic-fin rays i+4, all segmented, first largest, rays gradually decreasing mesially; fin smaller than the others, origin slightly in front of anal and uro-genital openings, margin reaching area close anal-fin origin; bases of contralateral fins not in contact. Dorsal fin elongated, with rounded posterior profile, posteriorly placed, its origin located on 67.4% SL; dorsal-fin rays i+6, first, second and third longest, branched rays with incipient branching at tips. Anal-fin rays ii+4, segmented rays, first and second longest, branched rays branching once; origin located on 68.9% SL, adjacent to posterior margin of anus, continuous with integument surrounding vent, similar shape and size of dorsal fin. Caudal fin large and round, continuous with remainder of caudal peduncle; caudal-fin rays i+5/5+i, middle two rays longest, branched rays branching only once. Procurrent caudal-fin rays at least eight dorsally and ventrally forming large part of caudal peduncle depth and merging gradually into principal caudal rays. Exact number difficult to determine in alcohol preserved specimen. Five branchiostegal rays visible by transparency.
FIGURE 1. Left lateral view of Stenolicmus ix, holotype, MPEG 15101, 19.0mm SL.
FIGURE 2. Drawing of left lateral view of Stenolicmus ix, holotype, MPEG 15101, 19.0mm SL.
Pigmentation in alcohol. Background color cream, slightly darker dorsally. Dorsum and flanks partially covered with irregularly distributed black chromatophores, slightly more concentrated dorsally, gradually scarce ventrally through flanks, until no pigmentation on belly. Dark chromatophores equally scattered on caudal peduncle with same concentration as in flank. Melanophores, similar to few defined stars, concentrated, forming poorly defined blotches dorso-laterally more concentrated on upper half of body on trunk and caudal peduncle. Caudal peduncle with several series of dotted lines of small chromatophores, posteriorly oblique, over myosepta, toward dorsal and ventral profiles, forming poorly defined stripes. Dorsal head partially covered by small chromatophores, smaller than dorsal region of trunk, mostly concentrated in regions between nostrils, snout, upper lip, maxillary barbel bases, interorbital and supraoccipital. Eyes black, sharp edges. Small area lateral to eyes without chromatophores. Few minute melanophores on cheek region and surrounding opercular and interopercular patches of odontodes. Ventral portion of head white, with few chromatophores on corners of lower lip closer to rictal barbel base. Dorsal and pectoral fins with few minute chromatophores at bases. No pigmentation over anal and pelvic fins. Caudal fin with few minute chromatophores at base, a small blotch between bases of two middle-rays. Habitat and ecological notes. The specimen of Stenolicnus ix was collected in the headwaters of the Rio Curuá, from a lotic area about 5m wide and less than a meter deep. A large amount of leaf litter was present on the river bed, and the margins were dominated by amphibious vegetation (Fig. 4). Fifteen species of fishes, including Characiformes, Siluriformes and Perciformes occur syntopically with Stenolicnus ix.
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FIGURE 3. Dorsal view of head of Stenolicmus ix, holotype, MPEG 15101. Bar = 1mm.
Distribution. Stenolicnus ix is known only from the type locality in the lower Amazon basin at the igarapé Curuá, Alenquer, Pará State, Brazil (Fig. 5). Etymology. The specific epithet, ix, refers to the Mayan word "Ix", term used to describe the jaguar (Panthera onca). The name refers to the color pattern of grouped patches scattered from the flanks to the dorsum, unique among its congeners and similar to the jaguar. Name in apposition. Gender masculine. Discussion. Based on the single available individual of S. ix, it was only possible to conduct the observation and analysis of its external anatomy and color pattern but not of its internal structure. Thus, the three synapomorphies proposed for Sarcoglanidinae (see Costa, 1994) cannot be observed in S. ix. In contrast, the presence of several characters proposed by de Pinna and Starnes (1990) as diagnostic of Stenolicmus justify the inclusion of the new species in the genus. The diagnostic characters for Stenolicmus present in the S. ix are: (1) elongated body, HL 17.9%; (2) absence of frontal and parietal fontanels; analysis of the skull roof of S. ix under a stereoscopic microscope showed absence of fontanels, with no visible trace of this structure even when pressuring the tegument with a utility needle in the sagittal line, indicating that the frontal bones are completely fused together and to the supraoccipital, which also shows no evidence of a fontanel; (3) opercular and interopercular odontode plates are well developed with seven major odontodes each; and (4) eight dorsal and ventral procurrent rays, visible with transmitted light, a number consistent with that present in S. sarmientoi but differing from all remaining genera of the subfamily. Conversely, the three following additional diagnostic features proposed by de Pinna and Starnes (1990) for Stenolicmus were not analyzed, because these are minute osteological structures that can only be seen in clear and stained specimens: posterior process of dorsal expansion of quadrate straight and narrow, pointed; absence of metapterygoid; and expanded distal half of maxilla. Eight dorsal and ventral procurrent rays were visible under transmitted light, a number consistent with that seen in S. sarmientoi but different from other genera of the subfamily. De Pinna and Starnes (1990) proposed in the diagnosis of Stenolicmus sarmientoi that the caudal peduncle is tall, however, its measurement of 8.5–9.5% SL,
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agrees with the proportions in other species of Sarcoglanidinae (de Pinna, 1989; Costa, 1994; de Pinna and Winemiller, 2000). In contrast, S. ix does have a distinctly tall peduncle (11.6% SL) when compared to other members of Sarcoglanidinae.
FIGURE 4. Type-locality of Stenolicmus ix, an unnamed stream, tributary of Igarapé Curuá, right bank tributary of the Rio Amazonas, 0°9'47.6''S and 55º11'1.2''W.
FIGURE 5. Map showing the type locality of Stenolicmus ix.
Most of species of Sarcoglanidinae, except for S. ix and Microcambeva riberae, have a pale or translucent color pattern, with only minute chromatophores sparsely scattered over the body, usually more concentrated dorsally on the body but not forming visible patches with a diameter similar or larger than the eye. In contrast, the patches present in S. ix and M. riberae have a distinct pattern. In S. ix, the patches are large, poorly defined, with a diameter equal to or, twice the diameter of the eye and irregularly distributed over the body, more concentrated in the dorsal region. In M. riberae, there are conspicuous dark patches, but smaller than the diameter of the eye, arranged in
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series of 9–13 patches along the midline of the flanks and in two series of patches along the dorsolateral and dorsal midline portions. Costa (1994) hypothesized that the more densely pigmented pattern observed in S. sarmientoi is a reversal within Sarcoglanidinae, a pattern that is evidently shared with S. ix. Thus, considering the proposal of Costa (1994), it is more parsimonious to interpret the color patterns observed in M. riberae and in the species of Stenolicmus as independent reversals. The distribution of species of the genus, apparently, is not limited to the physical and chemical conditions of the rivers, since S. sarmientoi occurs in whitewater of the Río Matos, tributary of the Río Apero, Mamoré system (Bolivia), and S. ix occurs in clearwater, also recorded for species of Typhlobelus and Pygidianops (Schaefer et al., 2005), both Glanapteriginae. The individual of S. ix was collected with a sieve by scraping sand and leaf litter from the river bed. It is not possible, though, to assert the type of environment used by S. ix, because no observations were made of the species in its natural habitat. However, we can suggest a sand-dwelling behavior for this species, considering where it was collected and the fact that most species of Glanapteryginae and Sarcoglanidinae are associated with sandy environments (Schaefer et al., 2005).
Acknowledgements The authors are grateful to the Secretaria Estadual de Meio Ambiente (SEMA) and Conservação Internacional do Brasil (CI) for financial support; to the Mineradora Rio Tinto (MRT) for logistic support; to the coordinator of the Projeto Diagnóstico da biodiversidade das Unidades de Conservação Estaduais do mosaico Calha Norte do Estado do Pará, A. Aleixo; to C. D. Santana for the critical reading of the manuscript; and to W. S. B. Mota for help in the field.
Literature cited Bockmann, F. A. and Sazima, I. ( 2004) Trichomycterus maracaya, a new catfish from the upper rio Paraná, southeastern Brazil (Siluriformes: Trichomycteridae), with notes on the T. brasiliensis species-complex. Neotropical Ichthyology, 2, 61–74. Costa,W. J. E. M., Lima, S. M. Q. and Bizerril, C. R. S. F. (2004) Microcambeva ribeirae sp. n. (Teleostei: Siluriformes: Trichomycteridae): a new sarcoglanidinae catfish from the Rio Ribeira do Iguape basin, southeastern Brasil. Zootaxa, 563, 1–10. Costa, W. J. E. M. and Bockmann, F. A. (1994) A new genus and species of Sarcoglanidinae (Siluriformes: Trichomycteridae) from southeastern Brazil, with a re-examination of subfamilial phylogeny. Journal of Natural History, 28, 715–730. Costa, W. J. E. M. (1994) A new genus and species of Sarcoglanidinae (Siluriformes: Trichomycteridae) from the Araguaia basin, central Brazil, with notes on subfamilial phylogeny Ichthyological Exploration of Freshwaters, 5, 207–216. Mattos, J. L. O., W. J. E. M. Costa, and C. de S. Gama (2008) A new minature species of Ammoglanis (Siluriformes: Trichomycteridae) from the Brazilian Amazon. Ichthyological Exploration of Freshwaters v. 19 (no. 2): 161–166. Myers, G. S. and Weitzman, S. H. (1966) Two remarkable new trichomycterid catfishes from the Amazon basin in Brazil and Colombia. Journal of Zoology, 149, 277–287. de Pinna, M. C. C. (1989) A new sarcoglanidine catfish, phylogeny of its subfamily, and an appraisal of the phyletic status of the Trichomycterinae (Teleostei, Trichomycteridae). American Museum Novitates, 2950, 1–39. de Pinna, M. C. C. (1998) Phylogenetic relationships of netropical Siluriformes (Teleostei: Ostariophysi); Historical overview and synthesis of hypotheses. In: L. R. Malabarba, Reis, R. E., Vari, R. P., Lucena, Z. M. S. and Lucena, C. A. S. (eds) Phylogeny and Classification of Neotropical Fishes, Edipucrs, Porto Alegre, Pp 279–330. de Pinna, M. C. C. and Starnes,W. C. (1990) A new genus and species of Sarcoglanidinae from the Río Mamoré, Amazon basin, with comments on subfamilial phylogeny (Teleostei, Trichomycteridae). Journal of Zoology, 222, 75–88. de Pinna, M. C. C. and Winemiller, K. O. (2000) A new species of Ammoglanis (Siluriformes: Trichomycteridae) from Venezuela. Ichthyological Exploration of Freshwaters, 11, 255–264. Schaefer, S. A., Provenzano, F., de Pinna, M. C. C., and Baskin, J. N. (2005) New and noteworthy Venezuelan glanapterygine catfishes (Siluriformes, Trichomycteridae), with a discussion of their biogeography and psammophily. American Museum Novitates, 3496, 1–27. Tchernavin. V. (1944) A revision of some Trichomycterinae based on material preserved in the British Museum (Natural History). Proceedings of the Zoological Society of London, 114, 234–275. Wosiacki, W. B. and de Pinna, M. C. C. (2007) Família Trichomycteridae: Sarcoglanidinae. In: P. A. Buckup, Menezes, N. M., and Ghazzi, M. S. (eds). Catálogo das Espécies de Peixes de Água Doce do Brasil, Museu Nacional, Rio de Janeiro, p74.
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