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Introduction
Loricariidae is the largest family of the Neotropical Siluriformes and is widespread from Costa Rica in the north to Argentina in the south (Weber, 2003). Ancistrus is one of richest loricariid genera, with 70 valid species (Fricke et al., 2019). The genus is easily distinguished from the other Loricariidae by having well-developed cheek spines, and the border of the snout naked, without plates, but ornamented with fleshy tentacles. Ancistrus is abundant in most museums or collections of fishes around the world, but often misidentified at species level due to the limited knowledge of its taxonomy. The type species of the genus, Ancistrus cirrhosus (Valenciennes, 1836), was described from Argentina, Buenos Aires and Misiones, but the holotype has never been found and may have not even been preserved (Fisch-Muller, 2003). Lack of a taxonomic revision of the genus has been the main cause of a never-ending list of taxonomic problems and difficulties with species recognition due to incomplete descriptions and lack of type material. Six species have been described from the rio Madeira basin: A. heterorhynchus (Regan, 1912) and A. marcapatae (Regan, 1904) from río Madre de Dios basin, Peru; A. bolivianus (Steindachner, 1915), A. megalostomusPearson, 1924 and A. montanus (Regan, 1904) from río Beni basin, Bolivia; and A. verecundus Fisch-Muller, Cardoso, da Silva, Bertaco, 2005 from the igarapé Piracolina, upper rio Madeira, Brazil.
During an expedition to Mosaico do Apuí, a group of differently categorized but contiguous conservation units in the southern region of the Amazonas state, a new and peculiar species of Ancistrus was collected from the rio Sucunduri, rio Madeira basin. Almost all Ancistrus representatives possess light spots or vermiculations over a dark background. The new species is remarkable in having a unique color pattern among its congeners, and it is described here along with comments on the taxonomic status of A. bolivianus, A. heterorhynchus and A. marcapatae.
Material and Methods
Measurements were taken using digital calipers to the nearest 0.1 mm, and are presented as percents of standard length (SL) or head length (HL). Counts were made under a stereomicroscope. Measurements and counts followed Fisch-Muller et al. (2001) and Bifi et al. (2009). Body plate nomenclature was based on Schaefer (1997), with modifications of Oyakawa et al. (2005). Specimens were cleared and stained (c&s) according to Taylor, Van Dyke (1985). Institutional acronyms: BMNH, Natural History Museum, London; CAS, California Academy of Sciences, San Francisco; INPA, Instituto Nacional de Pesquisas da Amazônia, Manaus; MCP, Museu de Ciências e Tecnologia, Pontifícia Universidade Católica do Rio Grande do Sul, Porto Alegre; MPEG, Museu Paraense Emilio Goeldi, Belém; MUSM, Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima; MZUSP, Museu de Zoologia da Universidade de São Paulo, São Paulo; NMW, Naturhistorisches Museum, Wien; ZMB, Berlin Zoological Museum, Berlin.
Ancistrus miracollis, new species
urn:lsid:zoobank.org:act:4D62A4E1-4BAF-4A2E-9112-3941327D3618
Holotype. INPA 57624, male, 66.7 mm SL; Brazil: Amazonas State: Apuí, comunidade Terra Preta, igarapé do Mureru, tributary of rio Sucunduri, rio Madeira basin, 7°45’45”S 58°49’00”W, 29 Jun 2006, L. H. Rapp Py-Daniel, C. E. Marinelli & C. S. da Silva.
Paratypes. All from Brazil: Amazonas State: Apuí: rio Madeira basin: INPA 26144, 1, 59.0 mm SL, igarapé located just off the trilha do Inferno, tributary of rio Sucunduri, 8°34’41”S 59°9’13”W, 23 Jun 2006, O. S. Pereira. INPA 26433, 27 (25 alc., 21.7-64.4 mm SL and 2 c&s 48.9-54.0 mm SL); MCP 54133, 2, 45.0-48.7 mm SL; MPEG 38161, 2, 51.1-56.2 mm SL; MZUSP 124264, 2, 47.5-59.5 mm SL, same data of holotype.
Diagnosis. Ancistrus miracollis is diagnosed from its congeners by having thin light vertical bands on the trunk, sometimes incomplete (vs. plain, with black or white spots, or unpigmented body). Furthermore, the new species can be distinguished from other Ancistrus species described from the rio Madeira basin by pectoral-fin length surpassing the pelvic-fin origin (vs. not reaching or just reaching the pelvic-fin origin in A. marcapatae, A. megalostomus and A. montanus); larger cleithral width 33.5-36.9% in SL (vs. 27.7-33.0% in A. montanus); smaller dentary width 45.3-54.4% in interorbital distance (vs. 64.6-86.6% in A. marcapatae and 64.9-91.4% in A. melagostomus); and by possession of an adipose-fin (vs. adipose-fin absent in A. verecundus).
Description. Morphometric data and counts in Tab. 1. Head and trunk moderately depressed. Dorsal profile of body convexly raising from tip of snout to dorsal-fin origin, then straight or slightly convex to adipose fin, and concave from that point to caudal fin. Ventral profile of body straight, slightly convex on caudal peduncle. Caudal peduncle compressed; slightly flattened ventrally.
Tab. 1 Morphometric and meristic data of Ancistrus miracollis. SD= standard deviation, N= number (including holotype).
| Characters | Holotype | N | Range | Mean | SD |
|---|---|---|---|---|---|
| Standard length (mm) | 66.7 | 21 | 44.5 - 67.4 | 55.5 | - |
| Percent of standard length | |||||
| Predorsal length | 47.7 | 21 | 42.8 - 47.7 | 45.5 | 1.2 |
| Head length | 39.2 | 21 | 35.2 - 39.2 | 36.7 | 1.0 |
| Occipital depth | 20.6 | 21 | 16.8 - 20.6 | 18.4 | 1.1 |
| Cleithral width | 36.3 | 21 | 33.5 - 36.9 | 34.9 | 1.0 |
| Dorsal-fin base length | 23.8 | 21 | 21.9 - 24.2 | 23.5 | 0.6 |
| Interdorsal length | 14.5 | 21 | 14.5 - 17.6 | 16.0 | 0.8 |
| Prepectoral length | 30.7 | 21 | 27.4 - 31.4 | 29.3 | 0.9 |
| Prepelvic length | 49.4 | 21 | 49.1 - 53.8 | 51.2 | 1.2 |
| Dorsal-fin spine length | 25.5 | 21 | 25.3 - 28.7 | 27.0 | 0.9 |
| Pectoral-fin spine length | 31.4 | 21 | 29.2 - 32.6 | 31.0 | 1.0 |
| Pelvic-fin spine length | 27.8 | 21 | 26.3 - 29.1 | 27.4 | 0.8 |
| Adipose-fin spine length | 8.9 | 21 | 8.0 - 11.1 | 9.3 | 0.6 |
| Anal-fin spine lenght | 10.0 | 20 | 8.0 - 10.6 | 9.3 | 0.7 |
| Thoracic length | 22.1 | 21 | 22.1 - 26.8 | 25.2 | 1.3 |
| Abdominal length | 22.0 | 20 | 19.1 - 22.4 | 21.0 | 0.8 |
| Upper caudal-fin spine length | 22.0 | 12 | 20.8 - 23.9 | 22.4 | 0.9 |
| Lower caudal-fin spine length | 30.2 | 18 | 29.3 - 36.3 | 32.7 | 2.1 |
| Caudal peduncle length | 26.9 | 20 | 26.9 - 29.4 | 27.8 | 0.7 |
| Caudal peduncle depth | 11.7 | 21 | 10.7 - 12.3 | 11.6 | 0.4 |
| Adipose-fin to caudal-fin length | 11.6 | 21 | 11.6 - 15.5 | 13.9 | 0.9 |
| Anal-fin to caudal-fin length | 34.3 | 20 | 31.2 - 35.8 | 33.2 | 1.3 |
| Percent of head length | |||||
| Supracleithral width | 83.8 | 21 | 82.2 - 89.2 | 85.4 | 2.0 |
| Snout length | 57.7 | 21 | 54.6 - 60.5 | 57.6 | 1.4 |
| Interorbital distance | 38.3 | 21 | 34.4 - 40.6 | 37.4 | 1.6 |
| Orbital diameter | 15.8 | 21 | 15.8 - 19.8 | 17.7 | 1.1 |
| Occipital-orbital distance | 42.8 | 21 | 37.8 - 43.3 | 40.7 | 1.6 |
| Dentary width | 19.3 | 21 | 17.3 - 19.7 | 18.7 | 0.8 |
| Count | |||||
| Lateral median series | 23 | 21 | 22 - 23 | 23.0 | 0.2 |
| Dorsal-fin base | 7 | 21 | 6 - 7 | 6.6 | 0.5 |
| Between dorsal and adipose | 5 | 21 | 5 - 6 | 5.5 | 0.5 |
| Between adipose and caudal | 5 | 21 | 5 - 7 | 5.9 | 0.5 |
| Between anal and caudal | 11 | 21 | 11 - 12 | 11.1 | 0.3 |
| Premaxillary teeth | 57 | 21 | 50 - 65 | 55.7 | 4.3 |
| Dentary teeth | 61 | 21 | 52 - 69 | 58.1 | 3.7 |
| Cheek spines | 33 | 21 | 17 - 33 | 21.8 | 4.1 |
Snout large and rounded in dorsal view, with large naked margin bordered by dermal platelets on lateral portion; extension of naked area on snout large, representing ⅔ of snout length. Adult males with small- to middle size tentacles (sometimes branched) along lateral border of snout and longitudinally aligned along mesethmoid, bifurcating caudally to nares; tentacles small and less numerous in females, limited to one series on lateral border of snout. Evertible cheek plates supporting (17-33) hypertrophied odontodes (cheek spines). Head covered by dermal bones; dorsum covered by dermal plates, except at dorsal-fin base.
Eye mid-sized, 15.8-19.8% of HL, dorsal orbit not raised; dorsolaterally positioned. Interorbital region slightly concave. Exposed portion of opercle roughly triangular; supra-opercular region with few platelets near compound pterotic.
Oral disk circular covered with small papillae; lower lip wide with papillae reducing in size toward its margin; maxillary barbel short, attached to lip by membrane and with reduced free tip. Premaxillary and dentary tooth rows short; teeth short, thin, numerous, bifid and curved inward. Cusps spatulated and asymmetrical, with mesial cusp larger and wider than lateral cusp. Only one small buccal papilla positioned between premaxillae.
Five series of lateral plates, three lateral series on the narrowest portion of caudal peduncle. Mid-dorsal and mid-ventral series not surpassing adipose fin. Median series supporting lateral line. Short odontodes on fin rays and body plates. Ventral surface devoid of plates from snout tip to anal-fin insertion. Base of first anal-fin pterygiophore exposed, forming preanal platelet-like element, sometimes covered by skin but supporting small odontodes.
Dorsal-fin origin situated slightly anterior to vertical through pelvic-fin origin; dorsal fin usually reaching or surpassing preadipose plate when adpressed; dorsal-fin spine flexible, shorter than head length. Adipose-fin spine short, slightly curved downward. Pectoral-fin spine inflexible and slightly curved inward, with hypertrophied odontodes and tentacles on its distal portion; pectoral-fin surpassing adpressed pelvic-fin origin. Pelvic fin flexible and curved inward, depressed pelvic-fin spine surpassing origin of anal fin. Anal fin short. Caudal-fin margin obliquely truncate with ventral unbranched ray longer than dorsal one. Fin-ray formula: dorsal II,7; pectoral I,6; pelvic i,5; anal i,3-4; caudal i,14,i. Total vertebrae: 27 (two specimens).
Color in alcohol. Body background color dark gray or brown. Dorsal part of head with rounded light spots, on predorsal and dorsum region in some specimens; light vertical bars on trunk, variably incomplete, usually more conspicuous on caudal peduncle region. Barred pattern showing some variation (Fig. 2). Ventral surface of head and abdomen yellowish to light brown, brown on ventral surface of caudal peduncle. All fins with alternating dark and light spots on rays, organized in transverse bands in some specimens.
Fig. 1 Ancistrus miracollis, INPA 57624, holotype, 66.7 mm SL, male; Brazil, Apuí, rio Sucunduri drainage, lower rio Madeira basin.
Fig. 2 Color pattern variation in Ancistrus miracollis. Standard length from top to bottom, left to right: 27.7 mm SL, 30.3 mm SL, 35.5 mm SL, 41.2 mm SL, 48.4 mm SL, 51.6 mm SL, 58.4 mm SL (all from INPA 26433), 60.1 mm SL (INPA 24144).
Sexual dimorphism. Ten males and 11 females measured; largest male and female with 66.7 mm and 67.4 mm SL, respectively. Mature males have small- to middle-sized tentacles in the dorsal region and border of snout. Females can have fewer and shorter tentacles than males limited to one series on lateral border of snout, usually two to four on each side of snout.
Geographical distribution. Ancistrus miracollis is only known from the Mosaico of Conservation Units of Apuí on southern Amazon State, near the border with Mato Grosso State, Brazil. The new species was found in small streams flowing to the rio Sucunduri, affluent of lower rio Madeira (Fig. 3).
Fig. 3 Partial map of the Brazilian Amazon, showing the distribution of Ancistrus miracollis. Red star indicates type locality.
Etymology. From the latim mirus = wonderful, surprising and collis = hill, mountain, in allusion to the beauty of the species with unique pattern color of Ancistrus and its sampling site in the highlands of the Parque Estadual do Sucunduri, more specifically in the Sucunduri Dome, an allusion to its elevation that can reach up to 350 m, very peculiar for this area. An adjective.
Conservation status. The type locality of A. miracollis (igarapé do Mureru) is not an easily accessible place and the sampling was made possible through governmental funds from the state of Amazonas (Secretaria de Desenvolvimento Sustentável do Amazonas - SDS 2010). The Mosaic of Apuí comprises nine conservation units, seven considered of sustainable usage, and two State Parks under full protection. Thus, we suggest that A. miracollis be categorized as LC (Least Concern) under the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2017) of extinction risk.
Comments on taxonomic status of Ancistrus marcapate: Three species have been described from ríos Beni and Madre de Dios basins: A. bolivianus, A. heterorhynchus and A. marcapatae (Fig. 4). The examination of the type material revealed no differences between these three species, but that they share some uncommon features such as: teeth with elongated principal cusp sharpened and at least three times larger than lateral cusp; pectoral-fin not surpassing the pelvic-fin origin; and anterior adipose-fin keel formed by four to six plates. Furthermore, these species have a slightly concave profile between adipose and caudal fins; dentary length (24.9-29.5% in HL), and fins with dark spots forming transverse bands. These characters combinations distinguish them from the majority of Ancistrus species. Thus, based on these observations we recognize A. bolivianus and A. heterorhynchus as junior synonyms of A. marcapatae (Fig. 5).
Fig. 4 Dorsal, lateral and ventral views (left to right) of Ancistrus bolivianus: NMW 43475, 65.6 mm SL, syntype; A. heterorhynchus: BMNH 1911.12.20.35-36, 63.2 mm SL, syntype; A. marcapatae: BMNH 1902.5.29.211, 79.1 mm SL, holotype.
Ancistrus marcapatae (Regan, 1904)
Chaetostomus marcapataeRegan, 1904:246, pl.14 (Fig. 1) [original description; type locality: Marcapata Valley, río Inambari basin, Peru].
Xenocara heterorhynchusRegan, 1912:668, pl.76 (Fig. 2) [original description; type locality: Urohuasi, río Inambari basin, Peru].
Xenocara bolivianaSteindachner, 1915:95, pl.9 (Figs. 5-6) [original description; type locality: río Songo, río Beni basin, Bolivia].
Chaetostoma marcapatae. -Isbrücker, 1980:62 [check list]. -Ortega, Vari, 1986:16 [check list]. -Fish-Muller, 2003:346 [check list]. -Ferraris, 2007:221 [check list].
Ancistrus bolivianus. -Isbrücker, 1980:66 [check list]. -Fish-Muller, 2003:374 [check list]. -Ferraris, 2007:219 [check list]. New Synonym.
Ancistrus heterorhynchus. -Isbrücker, 1980:69 [check list]. -Ortega, Vari, 1986:17 [check list]. -Fish-Muller, 2003:381 [check list]. -Ferraris, 2007:229 [check list]. New Synonym.
Ancistrus marcapatae. -Lujan et al., 2015b:673 [comments; new genus combination].
Examined material: Bolivia. Ancistrus bolivianus. NMW 43475, 2, 40.8-58.0 mm SL, syntypes of Xenocara bolivianaSteindachner, 1915. Nord Yungas, río Madre de Dios basin, río Songo, 1914, Schnel; NMW 43476, 27, 31.2-65.6 mm SL, Nord Yungas, río Madre de Dios basin, río Songo, 1915, Fassl. Ancistrus heterorhynchus. BMNH 1911.12.20.35-36, 2, 45.7-63.2 mm SL, syntypes of Xenocara heterorhynchusRegan, 1912, Madre de Dios basin, río Inambari basin. Peru. Ancistrus marcapatae. BMNH 1902.5.29.211, 79.1 mm SL, holotype of Chaetostomus marcapatae Regan, 1904, Marcapata Valley, río Inambari basin; MUSM 10087, 1, 88.5 mm SL, río Inambari basin; MUSM 57498, 1, 66.6 mm SL, río Inambari basin; MUSM 58097, 2, 57.9-59.9 mm SL, río Yunguyo, río Madre de Dios basin.
Discussion
Although there are differences between Ancistrus based on morphological (Armbruster, 2004, 2008) and molecular analyses (Lujan et al., 2015a), there is some resemblance between Ancistrus and LasiancistrusRegan, 1904 and Pseudolithoxus Isbrücker, Werner, 2001. Among these genera, only two species of Pseudolithoxus have a similar color pattern to A. miracollis: P. tigris (Armbruster, Provenzano, 2000) and P. kelsorum (Lujan, Birindelli, 2011), besides other genera like Dekeyseria Rapp Py-Daniel, 1985, Hypancistrus Isbrücker, Nijssen, 1991, Peckoltia Miranda Ribeiro, 1912 and Panaqolus Isbrücker, Schraml, 2001. However, all can be distinguished from Ancistrus by having plates or odontodes on the snout and the lack of fleshy tentacles in adult male.
Seven valid species of Ancistrus are recorded from the rio Madeira basin (Fish-Muller, 2003; Ferraris, 2007): A. dolichopterus Kner, 1854; A. dubius Eigenmann, Eigenmann, 1889; A. hoplogenys (Günther, 1864); A. marcapatae; A. megalostomus; A. montanus and A. verecundus; and three additional species probably new to science: Ancistrus sp. “sideral”; Ancistrus sp.1 “baixinho” and Ancistrus sp.2 “sotério” (Zawadzki, Chamon, 2013). None of these species present the color pattern of A. miracollis, having instead a dark background with pale dots on the body or lacking spots.
The río Beni basin, upper rio Madeira, is included within the Mamore-Madre de Dios Piedmont Ecoregion with 21-29% endemic species of freshwater fish (Abell et al., 2008). However, few recent studies have been published contributing to the limited taxonomic understanding of the ichthyofauna from that region. Ancistrus marcapatae shares the presence of a keel formed by preadipose plates with A. bufonius (Valenciennes, 1840), A. greeni (Isbrücker, 2001), A. montanus, A. tolimaTaphorn, Armbruster, Villa-Navarro, Ray, 2013 and A. vericaucanus; and teeth with sharp elongated principal cusp, at least three times larger than lateral cusp with A. bufonius and A. montanus. Ancistrus marcapatae can be diagnosed by the orbital diameter (14.0-16.7% in HL vs. 12.3-14.1% in A. bufonius); tooth shape (bicusp vs. unicusp in A. greeni); and dentary width (24.9-29.5% in HL vs. 18.0-21.3% in A. montanus, 14.2-23.4% in A. tolima and 12.7-14.8% in A. vericaucanus, data on the last two species from Taphorn et al., 2013).
Despite major contributions to the knowledge of the ichthyofauna of the rio Madeira basin lately (Queiroz et al., 2013), the species composition of this basin is still poorly known. The apparent endemic presence of some loricariids suggests that the family is highly successful and diverse in the region.
Comparative material examined. Material examined in addition to that listed by Bifi et al. (2009) and de Oliveira et al. (2015, 2016). Ancistrus claro. MCP 28667 (ex ZMB 32918), 67.8 mm SL, holotype of A. claro Knaack, 1999, Brazil, Mato Grosso, rio Cuiabá basin. Ancistrus cryptophthalmus. MCP 10523, 1, 49.2 mm SL, paratype of A. cryptophthalmus Reis, 1987, Brazil. Ancistrus cuiabae. MCP 28671 (ex ZBM 32920), 112.8 mm SL, holotype of A. cuiabae Knaack, 1999, Brazil, Mato Grosso, rio Cuiabá basin. Ancistrus galani. MCP 15634, 1, 55.9 mm SL, paratype of A. galani Peres, Vilória, 1994, Venezuela, Zulia, río Socuy. Ancistrus greeni. BMNH 1903.10.12.3-4, 2, 44.8-51.4 mm SL, syntype of C. maculatusRegan, 1904, replaced by C. greeni Isbrücker, 2001, Peru, Rozmaiu. Ancistrus malacops. INPA 2393, 2, 55.0-69.1 mm SL, Brazil Amazonas, rio Japurá; INPA 49272, 7, 29.3-110.8 mm SL, Brazil Amazonas, rio Japurá. Ancistrus megalostomus. CAS 64614, 2, 81.7-83.5 mm SL syntypes of A. megalostomusPearson, 1924, Huachi, Bolivia, río Beni basin; MUSM 10366, 1, 64.9 mm SL, Peru, Sandia, rio Candamo; MUSM 11606, 2, 70.5-85.5 mm SL, Peru, rio Ebehuabaeji basin. Ancistrus montanus. BMNH 1902.12.18.4, 81.3 mm SL, holotype of X. montana Regan, 1904, Bolivia, Tumupasa, río Beni basin; MUSM 57817, 1, 82.0 mm SL, Peru, Paucartambo, rio Blanco; MUSM 57830, 1, 48.5 mm SL, Peru, rio Huacaria.
