Astronotus mikoljii, Lozano & Lasso-Alcalá & Bittencourt & Taphorn & Perez & Farias, 2022

Lozano, Alfredo Perez, Lasso-Alcala, Oscar M., Bittencourt, Pedro S., Taphorn, Donald C., Perez, Nayibe & Farias, Izeni Pires, 2022, A new species of Astronotus (Teleostei, Cichlidae) from the Orinoco River and Gulf of Paria basins, northern South America, ZooKeys 1113, pp. 111-152 : 111

Astronotus mikoljii sp. nov.

; Figs 3 , 4 , 5 , 6 , 8a-8 , 9 , 10

Synonymy.

Astronotus ocellatus . Fowler 1911: 437 (first description with specimens from Venezuela); Luengo 1963: 337 (listed); León 1966: 1127-1134 (brief note); Fernández-Yépez and Antón 1966: 83 (listed); Mago 1967: 259 (listed); Mago 1970a: 76, 78, 80, 87, 88, 92, 96 (biological data), 1970b: 20 (picture, notes), 1978: 14, 15, 17, 22 (picture, brief description); Novoa and Ramos 1978: 134-138 (note, picture); Kullander 1981: 682, 683 (morphological description of Orinoco specimens, distribution); Román 1981: 62, 136 (identification key, picture, note); Cervigón 1982: 354 (picture); Novoa et al. 1982: 312-313, fig. 62 (biological and ecological data, picture); Cervigón 1983: 118-119 (experimental aquaculture); Ginéz and Olivo 1984: 159 (note); Ginéz et al. 1984: 184 (notes); Taphorn and Lilyestrom 1984: 70, 71, 74, 75, 75, 83, 84 (ecological data); Román 1985: 33 (brief morphological description, note, picture); Kullander 1986: 68 (taxonomic status); Novoa 1986: 245 (note); Machado-Allison 1987: 30, 31, 32, 39, 42,43, 47, 48, 60, 61, 62, 94, 114 (biological and ecological data, juvenile picture); Machado-Allison et al. 1987: 136 (listed); Lasso 1988: 371, 372, 381 (list, note); Román 1988: 62 (identification key, picture); Rengifo 1989: 9-16 (note); Winemiller 1989a: 180 (ecological data), 1989b: 241 (ecological data); Novoa 1990: 396 (listed); Rodríguez and Lewis 1990: 322 (listed); Winemiller 1990: 665-672 (ecological data), 1991: 360 (ecological data); Monente 1992: 137 (note); Román 1992: 33 (picture, notes); Machado-Allison 1993: 30, 31, 39, 43, 48, 61, 94, 114 (biological and ecological data, picture); Machado-Allison and Moreno 1993: 83 (note); Royero 1993: 98 (listed); Barbarino-Duque and Taphorn 1994: 100, 101 (note, picture); Winemiller 1996: 111, 112, 129 (ecological data); Winemiller et al. 1996: 26, 38 (biological and ecological data); Rodríguez and Lewis 1997: 114 (ecological data); Fuller et al. 1999: 415 (listed); Lasso et al. 1999: 28 (listed, note); Mojica 1999: 564 (listed, note); Maldonado-Ocampo 2001; 68, 71 (listed, note): Lasso et al. 2003a: 188 (listed, note), 2003b: 244 (listed, note), 2003c: 287 (listed, brief description, note); Machado-Allison 2003: 568 (listed, note); Ajiaco-Martínez et al. 2012: 144 (listed); Herrera et al. 2012: 65 (listed); Machado-Allison et al. 2013: 305, 307, 332 (listed, note); Ortega-Lara 2016: 81 (picture, listed); Ramírez-Gil and Ajiaco-Martínez 2016: 131 (table 3: listed); DoNascimiento et al. 2017: 99 (listed, note); Winemiller et al. 2018: 5, 6 (listed, ecological data).

Astronotus cf. ocellatus . Lasso et al. 1999: 28 (listed); Lasso and Machado-Allison 2000: 56, 57, 154 (diagnostic features, type locality, note, picture); Lasso et al. 2003b: 244 (listed, note), 2003c: 287 (listed, taxonomic note); Lasso 2004: 377,378 (diagnostic, features, biological and ecological data); Taphorn et al. 2005: 24, 30, 32, 34 (listed, notes); Medina and Bonilla 2006: 3, 4, 6, 9 (picture, genetic data); Marcano et al. 2007: 46 (listed); Brito et al. 2011: 310 (diagnostic features, note, picture); Echeverría and Machado-Allison 2015: 81, 83 (listed), Machado-Allison et al. 2018: 442, 443, 454, 455, 483 (picture, painting, morphologic description, biological and ecological data).

Astronotus sp. Lasso et al. 2003a: 188 (ecological data); Rodríguez-Olarte et al. 2003: 205, 211 (listed ecological data); Antonio and Lasso 2004: 92, 93, 107 (diagnostic features, comparative material, note); Campo 2004: 59 (listed); Hoeinghaus et al. 2004: 88, 92 (listed, notes); Lasso et al. 2004: 148 (listed, note); López-Fernández et al. 2005: 646, 649-651 (morphological characters); Galvis et al. 2007: 272, 394 (diagnostic features, note, picture); Lasso et al. 2009a: 119 (listed, note), 2009b: 143 (listed, note), 2010: 57, 71 (listed, brief description, note); Machado-Allison et al. 2010: 223 (listed); Lasso et al. 2011a: 64 (listed, note), 2011b: 102-108 (listed, identification key); Villa-Navarro et al. 2011: 277 (listed); Machado-Allison et al. (2013): 305, 307, 332 (listed, notes); Lasso et al. 2014: 103 (note, picture); Usma et al. 2016: 117 (listed).

Type material.

Holotype. MCNG 56677 (225.1 mm SL), Venezuela. Estado Apure, Pedro Camejo Municipio in a small stream (tributary of the Arauca River), 07°33'14.08"N, 67°38'44.06"W, 13 Jun 2015, Pérez A. and Alfonso R. leg. (Fig. 3 ; Tables 1 , 2 ).

Paratypes. MCNG 56678 (5, 175.3-200.4 mm SL); MBUCV 35750 (1,144.4 mm SL); MHNLS 26123 (1, 140.4 mm SL); INPA-ICT 057800 (2, 112.3-143.4 mm SL); EBRG 11061 (1, 152.2 mm SL), Venezuela, Estado Apure, Municipio Pedro Camejo, small tributary stream of the Arauca River, same date and collectors as holotype; Venezuela, ANSP 37896 (1, 124.5 mm SL). Estado Monagas, Las Piedritas Caño Uracoa, 24.9 km SW of Uracoa, 8°48'9.00"N, 62°28'25.00"W, 12 Feb 1911, Bond F. and Brown S. leg.; MHNLS 198 (5, 97.5-116.7 mm SL) Estado Apure, Achaguas, Río Apure, 7°55'35"N, 68°28'47"W, 10, Jan 1951, Fernández-Yépez A. leg.; MHNLS 3551 (2, 109.1-121.9 mm SL). Estado Anzoátegui Laguna de Mamo, 1 km south of Juasiullal, right bank of the Orinoco River, 7°25'57"N, 63°7'8"W, 22 Jan 1981, Feo G., Pérez L., Ovidio H. leg.; MHNLS 3776 (3, 98.7-115.9 mm SL) Estado Bolivar, Orinoco River, Fajardo Island Main channel, May 05, 1975, Köpke H.; MHNLS 3777 (1, 119.1 mm SL) Estado Bolivar, Orinoco River, Fajardo Island Main channel, 19 Apr 1974, Köpke H. leg.; MHNLS 4850 (1, 79.1 mm SL) Estado Bolivar, Rio Claro Lagoon, approximately 15 Km East of San Félix, 02 Apr 1986, Pérez L. leg.; MHNLS 4914 (1, 121.7 mm SL) Estado Bolivar, Residual Lagoon, Hato Puga; approximately 25 km East of San Felix, 11 Apr 1986, Pérez L. leg.; MHNLS 4915 (1, 121.6 mm SL) Estado Bolivar, Laguna Chirere approximately 30 km west of Puerto Ordáz, 04 Apr 1986, Pérez L. leg.; MHNLS 4916 (1, 117.3 mm SL) Estado Bolivar, Laguna Río Claro approximately 15 km East of San Felix, 07 Apr 1987, Lasso C. Pérez L. leg.; MHNLS 7860 (2, 94.0-107.5 mm SL) Estado Cojedes, El Baul, 8°54'48.60"N, 68°17'17.52"W, 15 Apr 1984, B. Román leg.; MHNLS 9022 (1, 85.3 mm SL) Estado Bolivar, Caicara del Orinoco, Rio Aripao to Chaviripa River, 26 Mar 1986, B. Román leg.; MHNLS 9050 (1, 125.6 mm SL) Estado Guárico, Esteros de Camaguán, 6 May 1984, B Román leg.; MHNLS 11719 (1, 118 mm SL) Estado Apure, Caño Guaritico Hato El Frío, 7°52'35.00"N, 66°55'57.00"W, 18 Jan 1991, Lasso-Alcalá O. Lasso C. leg.; MHNLS 13094 (1, 201.5 mm SL) Estado Bolivar, Laguna Patiquín floodplain Caño Mato, tributary of Caura River, 7°9'16.00"N, 65°11'57.00"W, 23 Mar 1998, Vispo, C. leg.; MHNLS 13812 (2, 108.7-119.3 mm SL) Estado Delta Amacuro, Orinoco River Delta, Caño Ibaruma, Serranía de Imataca, 8°1'0.00"N, 60°47'0.00"W, 24 Jan 2003, Ponte V. leg.; MCNG 3608 (1, 148.9 mm SL) Estado Apure, Modules of UNELLEZ area adjacent to south of dike Caño Caicara, 7°25'30.00"N, 69°32'20.00"W, 2 Jun 1981, Donald Taphorn leg.; MCNG 2522 (1, 106.6 mm SL) Estado Apure, 3.4 km south of Bruzual bridge west side of road, 8°01'20.00"N, 69°20'50.00"W, 17 Nov 1980, Donald Taphorn leg.; MCNG 1832 (1, 118.5 mm SL) Estado Apure, 3.4 km south of Bruzual bridge 8°01'20.00"N, 69°20'50.00"W, 15 Nov 1980, Donald Taphorn leg.; MCNG 5993 (1, 101.3 mm SL) Estado Apure, Hato el Frio, 30 Sep 1979, Craig Lilyestrom leg.; MCNG 4994 (3, 193.1-210.1 mm SL) Estado Apure, Modules Fernando Corrales (UNELLEZ) dike east, 7°29'30.00"N, 69°31'W, 27 Nov 1981, Donald Taphorn leg.; MCNG 32543 (1, 101.6 mm SL) Estado Barinas, culvert 10 km NW of Libertad on road to Barinas 8°20'3.00"N, 69°43'41.00"W, 25 Jan 1995, John Armbruster leg.; MCNG 1675 (4, 197.4-240.7 mm SL) Estado Barinas, borrow pit at end of runway at Arismendi, 8°29'50.00"N, 68°21'20.00"W, 14 Sep 1980, Donald Taphorn leg.; MCNG 32596 (1, 161.9 mm SL) Estado Barinas, Río Caipe, to the east of town La Luz, 8°24'31.00"N, 69°48'19.00"W, 26 Jan 1995, John Armbruster leg.; MCNG 26930 (2, 112.50-104.90 mm SL) Estado Cojedes, San Geronimo in Hato Santa Clara, 02 Nov 1991, Manuel Gonzalez Fernandez leg.; MCNG 789 (2, 185.6-193.4 mm SL) Estado Delta Amacuro, Caño Paloma Orinoco River Delta, 21 Feb 1978, John Lundberg leg.; MCNG 32033 (1, 195 mm SL) Estado Guárico, P.N. Aguaro-Guariquito, Río Aguaro at El Paso to Médano Gómez, 7°50'27.00"N, 66°30'23.00"W, 01 Nov 1995, Donald Taphorn leg.; MCNG 32006 (2, 152.2 mm SL) Estado Guárico, P.N. Aguaro-Guariquito, Río Aguaro in Laguna Begonia, 7°52'6.00"N, 66°30'36.00"W, 01 Nov 1995, Donald Taphorn leg.; MCNG 25187 (1, 183.3 mm SL) Estado Guárico, Calabozo highway, Camaguán, 14 Jan 1982, Otto Castillo leg.; MCNG 32739 (1, 180.1 mm SL) Estado Guárico, P.N. Aguaro-Guariquito, Laguna Médano Gómez, 06 Aug 1995, Aniello Barbarino-Duque leg.; MCNG 11580 (2, 101.8-122.3 mm SL) Estado Guárico, borrow pit in savannah 2.3 km from San Fernando de Apure between km 305 and 306, 7°55'20.00"N, 67°28'20.00"W, 22 Mar 1981, Donald Taphorn leg.; MCNG 26815 (3, 90.5-109.0 mm SL) Estado Portuguesa, Caño Maraca, 8°53'11.00"N, 69°29'18.00"W, 13 Jan 1992, Larry Page, Pat Ceas, Brooks Burr, Steve Walsh, Chris Taylor, Leo Nico, Kirk Winemiller leg.; MCNG 15461 (1, 127.4 mm SL) Estado Portuguesa, Brazo del Caño Maraca at ranch of Darío Urriola, 26 Oct 1984, Kirk Winemiller leg.; MCNG 9097 (3, 112.3-138.1 mm SL) Estado Portuguesa, borrow pit N of Moritas east of Guanare-Las Moritas road, 8°45'30.00"N, 69°34'30.00"W, 03 Jan 1979, Donald Taphorn leg.; MCNG 5740 (1, 110.6 mm SL) Estado Portuguesa, Caño Maraca at bridge via Guanarito, Km 60, 8°49'50.00"N, 69°20'20.00"W, 28 Aug 1980, Donald Taphorn leg.; MCNG 29650 (1, 112.3 mm SL) Estado Portuguesa, Caño San José between Guanarito and La Capilla, 8°41'9.00"N, 68°56'49.00"W, 01 Mar 1994, John Armbruster leg.; Colombia • MHNLS 23575 (1, 114.7 mm SL), Departamento de Vichada, Caño drainage of Laguna Cajaro right bank of the Guaviare River, 3°58'14.00"N, 67°59'8.00"W, 16 Feb 2008; C. Lasso M. Sierra. M. Patiño F. Villa. A. Ortega. leg.; MHNLS 24053 (1, 218 mm SL), Departamento de Vichada, Caño Vitina right bank affluent, Rio Inírida upstream from Caranacoa beach, 3°44'30.00"N, 67°56'10.00"W, 21 Feb 2008, C. Lasso. M. Sierra M. Patiño F. Villa A. Ortega. leg.; MHNLS 24054 (1, 227.5 mm SL), Departamento de Vichada, Caño Vitina tributary right bank Río Inírida, upstream from Playa de Caranacoa, 3°44'30.00"N, 67°56'10.00"W, 21 Feb 2008, C. Lasso M. Sierra M. Patiño F. Villa; A. Ortega leg.; MHNLS 24059 (1, 205.5 mm SL), Departamento de Vichada, Peluame Lagoon, left Bank Guaviare River, near Guaviare-Inírida Confluence, 3°57'51.00"N, 67°55'W, 17 Feb 2008, C. Lasso M. Sierra M. Patiño F. Villa A. Ortega; S. Usma leg.; MHNLS 24061 (1, 211.5 mm SL), Departamento de Vichada, Laguna Bolívar, left bank, flooded area, Orinoco River, between Guanayana and Amanaven farms, 4°7'N, 67°45'W, 26 Feb 2008, C. Lasso M. Sierra M. Patiño F. Villa leg.; MHNLS 24064 (1, 226 mm SL), Departamento de Vichada, Caño Vitina, tributary right bank Río Inírida, upstream of Playa de Caranacoa, 3°44'30.00"N, 67°56'10.00"W, 21 Feb 2008, C. Lasso M. Sierra M. Patiño F. Villa; A. Ortega leg.

Comparative material.

Astronotus ocellatus . NPA-ICT 026472 (1) Brazil, Amazonas, Catalão, rio Solimoes Bacia do Solimoes , 3°9'34.00"S, 59°54'44.00"W, 20 Dec 2002 ; INPA-ICT 050911 (1) Brazil, Amazonas, rio Solimões, Ilha da Paciencia , 3°20'5.60"S, 60°12'11.30"W, Manaquiri, 18 Dec 2011; J. Santos, R. Orta, F. Pena leg. ; INPA-ICT 050912 (1) Brazil, Amazonas, rio Solimões, Ilha da Paciencia , 3°20'5.60"S, 60°12'11.30"W, Manaquiri, 18 Dec 2011; J. Santos, R. Ota, F. Pena leg. ; INPA-ICT 033076 (1) Brazil, Tabatinga, rio Solimoes , 3°57'32.00"S, 69°20'19.00"W, town of Palmares, 02 Sept 2003; Jansen Zuanon leg. ; INPA-ICT 033913 (1) Brazil, Amazonas, São Sebastião de Uatumã, rio Uatuma , 30 Oct 2009; R. Leitão, R. Lazzarotto leg. ; INPA-ICT 033889 (1) Brazil, Amazonas, rio Nhamunda , 2°13'51.00"S, 56°46'23.00"W, município Nhamunda, 21 Sept 2009; R. Leitão, R. Lazzarotto leg. ; INPA 050452 (2) Brazil, Amazonas, rio Preto da Eva , 2°44'38.10"S, 59°28'38.60"W, highway AM-010, km 110, 20 Aug 2014 ; INPA 22331 (1) Brazil, Amazonas, Lago do Boto, RDS do lago Piranha, Manacapuru , 30 Jan 2003 ; Ivanildo; INPA-ICT 033437 (2) Brazil, Amazonas, Lago Ressaca Grande, rio Solimoes , 2°28'26.00"S, 66°9'17.00"W, Fonte Boa, 08 Sept 2003; Jansen Zuanon leg. ; INPA 17486 (1) Brazil, Amazonas, pool in Lago Secado, rio Purus , Santa Lucia, 03 Jun 2001; Lucia Rapp-Daniel leg. ; INPA 17364 (3) Brazil, Amazonas, Lago Campinas, rio Purus , 05 Jun 2001; Lucia Rapp Py-Daniel leg ; INPA-ICT 029312 (49) Brazil, Amazonas, RDS Uacari, stream near community of Pupunha ; 5°35'47.00"S, 67°47'13.00"W; 26 Nov 2007; Martins, A.R. leg. ; INPA-ICT 007143 (1) Brazil, Para, Rio Cupari, near mouth of Tapajon River , 3°44'31.00"S, 55°23'25.00"W, 27 Oct 1991; Zuanon, J.A. leg. ; INPA-ICT 007170 (1) Brazil, Para, Rio Cupari, near mouth of Tapajos River ; 27 Oct 1991; Zuanon, J.A. leg ; INPA-ICT 007333 (1) Brazil, Tocantins, Rio Tocantins, Icangui; Brazil, Pará, Tucuruí, 3°49'49.80"S, 49°38'21.84"W, 28 Jun 1980 ; Equipe de Ictiologia do INPA leg.; INPA-ICT 020454 (1) Brazil, Tocantins, Lago das Ariranhas , rio Araguaia ; Brazil, Tocantins, Caseara , 9°14'5.28"S, 49°57'59.76"W, 11 Nov 2000 ; Equipe de Ictiologia do INPA leg.; INPA-ICT 020663, (2) Brazil, Tocantins, Rio Tocantins, Jabutizão, 7°43'55.56"S, 49°28'31.80"W, 10 May 2000; Santos, G.M. leg ; INPA-ICT 040585 (1) Brazil, Pará, Mercado do Porto, collected from stream tributary to Xingu River, near Vitoria do Xingu , 2°52'51.00"S, 52°0'45.00"W, 23 Sept 2013; Sabaj, M. H. leg ; INPA-ICT 043339 (6) Brazil, Pará, Xingu River, specimens bought in market, near Tucuri stream around Vitoria do Xingu ; 07 Mar 2014; Martins, A.R. leg.

Astronotus crassipinnis . INPA-ICT 021697 (1) Brazil, Rondônia, rio Novo, Guaporé, 11°29'29.00"S, 64°34'34.00"W, 27 Jul 2003 ; Torrente Vilara; INPA-ICT 038549 (2) Lago do Bodo, Bom Jardim , Porto Velho ( Brazil, Rondônia), 8°32'31.00"S, 63°37'26.00"W, 12 Ago 2011, L. Costas, F. Viera, leg. ; INPA-ICT 049921 (3) Brazil, Rondônia, Rio Guaporé, Surpresa , 10°06'11"S, 65°38'44"W, 21 Set 1985; G.M. dos Santos leg. ; INPA-ICT 049922 (2) Brazil, Rondônia, mouth of Guaporé River, near Surpresa , 11°19'44"S, 64°60'11"W, 16 Jun 1984; Costa Marques, G.M. dos Santos leg. ; INPA-ICT 049923 (1) Brazil, Rondônia, Rio Pacaás-Novos, blackwater flooded forest ca. 15 km upstream from mouth of Pacaás Novos River, Guajará-Mirim, 02 Apr1987, G.M. dos Santos leg.

Diagnosis.

The new species is distinguished from congeners by the following combination of characters: two or three supraneural bones (Fig. 4 ) (vs. two); absence of the spinous process (hypurapophysis) on the anterosuperior border of the parahypural bone (hypural complex) in Astronotus mikoljii sp. nov. (vs. present in A. ocellatus and A. crassipinnis ) (Fig. 5 ). The sagitta otolith in A. mikoljii sp. nov. is oval, with strongly crenulated ventral and dorsal margins (vs. elliptical and smooth-lobed margins in A. crassipinnis , and elliptical and smooth-dentate margins A. ocellatus ); the rostrum is projected with an elongated process, in A. mikoljii sp. nov. (vs. rostrum process short in A. crassipinnis and A. ocellatus ); the posterior region of the sagitta otolith is rounded in A. mikoljii sp. nov. (vs. straight or flat in A. crassipinnis and A. ocellatus ) (Fig. 6 ). The aspect ratio of sagitta otoliths in A. mikoljii sp. nov. (AR = 0.665) is higher than that of A. ocellatus (AR = 0.606), and A. crassipinnis (AR = 0.585), and the differences are statistically significant at P <0.05. The roundness index was highest in A. mikoljii sp. nov. (Rd = 0.597) vs. A. ocellatus (Rd = 0.545) and A. crassipinnis (Rd = 0.543) (P <0.05). Also the morphometric index showed higher values in A. mikoljii sp. nov. compared to A. ocellatus (0.837 vs. 0.767) and A. crassipinnis (0.735) (Suppl. material 1: Table S2). The new species also is distinguished from congeners by the following combination of morphometric characters: the mean head length of A. mikoljii sp. nov. (36.72% SL) is longer than that of A. crassipinnis (35.01% SL), and also A. ocellatus (33.26% SL); the mean diameter of the orbit of A. mikoljii sp. nov. (9.06% SL) is greater than that of A. ocellatus (7.36%SL) and that of A. crassipinnis (7.73% SL); the mean pre-orbital depth of A. mikoljii sp. nov. (14.22% SL) is greater than that of A. crassipinnis (10.14% SL) but less than that of A. ocellatus (15.91% SL); the mean snout length of A. mikoljii sp. nov. (11.53% SL) is longer than that of A. crassipinnis (5.36% SL), and A. ocellatus (10.67% SL) (Tables 1 , 2 ).

Description.

Morphology. Morphometric and meristic data are presented in Table 3 . Body moderately oval; laterally compressed, widest at region of anterior flank and posterior part of head; Dorsal-fin base contour sloping from about middle of spinous portion. Caudal peduncle edges horizontal; ventral sometimes longer than dorsal. Head and snout short; orbit slightly below forehead contour, entirely in upper and anterior halves of head. Interorbital wide, slightly convex. Tip of exposed maxilla extending to anterior edge of orbit; lower jaw articulation below middle of orbit. Both lip folds interrupted, junction of upper and lower lips African type. Opercula and pectoral girdle bones smooth. Interorbital convex; pre-pelvic contour straight; greatest body depth at pelvic-fin bases.

Scales. Pre-dorsal midline scales irregularly arranged, ca. 14-18 along midline; posterior pre-pelvic scales about half size of flank scales, slightly smaller anteriorly, in ca. seven horizontal series. Scales around caudal peduncle 26-32; lower lobe of caudal fin with 1-8 tubed lateral-line scales, from base to middle usually with gaps between them, and from half to edge of fin continued by pored scales). Anterior 1/3 to 1/2 of the cheek naked, remainder with cycloid scales; cheek scale rows 3 (n = 65; range 7-9). Operculum covered with eight cycloid scales (n = 65; range 3-5); opercula scales in ca. four vertical series, sub-opercular scales in two or three series: inter-operculum with one or two scales close to pre-opercular corner and six or seven scales in principal series. Pre-operculum naked. Soft unpaired fins covered by dense scale layer. Spinous dorsal fin bordered by posteriorly progressively wider scale layer with straight margin. This basal scale layer continued onto basal 1/3 of soft dorsal fin but inter-radial scales distal to it widen scaly layer to basal 1/2 of fin medially. Pectoral and pelvic fins naked. Inter-pelvic squamation extended laterally to cover bases. Caudal fin completely scaled save for narrow zone along hind margin; basal scales ctenoid; inter-radial scales cycloid in three or four series between rays.

Fins. One continuous dorsal fin, with anterior portion of hard rays (spines) and posterior portion with soft rays. First dorsal-fin spine inserted slightly in advance of vertical from hind margin of operculum; relative length of spines increasing to 4th then subequal to last few which are longer, twice length of first or slightly longer. Soft part of dorsal fin with rounded tip, reaching to not quite middle of caudal fin or to 3/4 of caudal fin. D. XII.18 (3), XII. 19 (4), XII. 20 (5), XIII. 17 (5), XIII. 18 (8), XIII. 19 (14), XIII. 20 (12), XIII. 21 (5), XIV. 18 (4), XIV. 19 (5), XIV. 20 (3); Anal-fin origin opposite soft dorsal-fin origin; soft portion similar to soft dorsal fin, but not reaching beyond middle of caudal fin. A. III. 14 (5), III. 15(10), III. 16 (15), III. 17 (10), III. 18 (14), III. 19 (3), III. 20 (1). Pectoral-fin with blunt dorsal tip, 4th ray longest, hind margin truncate or slightly curved; sometimes reaching to first anal-fin spine P1. 15 (n = 65; range 14-17). Pelvic-fin spine inserted below pectoral axilla; fin pointed, with outer branch of first ray longest, reaching to first anal-fin spine to 1/3 of soft-anal fin base, inner rays gradually shorter P2, 1.5 (1.5). Caudal fin with hind edge rounded, with 22 (n = 65; range 19-24), total rays (Table 3 ).

Gills. First gill arch with rudimentary denticles exposed laterally, two or three on epibranchial, one in angle, and 8-11 on ceratobranchial. Tiny gill-rakers present externally on medial side short, compressed and heavily denticulate (Table 3 ).

Teeth. Lower jaw with two teeth rows on each side (external and internal). External tooth row in both jaws extends from tip to end of each bone (dentary and maxilla). Teeth in outer series stout, conical, pointed, little recurved; anterior three or four in each jaw half as strong as rest; outer series to near end of upper jaw (20) and of corresponding length in lower jaw; inner band of very small weak teeth, less than 0.4 mm long, only anteriorly in jaws.

Otoliths . Sagitta otoliths oval with crenulate posterior, dorsal, ventral margins; Ar was greater than 0.66, otolith Rd 0.59 (Suppl. material 1: Table S2). Anterior region (rostrum) projected with elongated process and rounded posterior region. Anti-rostrum short and rounded, moderately broad ostium incisure with notch. Acoustic canal (sulcus acoustics) heterosulcoid, ostial, medial; ostium rectangular and shorter than caudal colliculum, which is tubular, closed, and strongly curved along its posterior margin.

Dorsal and vertebral skeleton. Pre-caudal vertebrae 15, caudal vertebrae 17, and total vertebrae 32. Range in vertebral counts (pre-caudal, caudal, and total) is wide (14-16, 15-18, 30-33). Two or three supraneural bones present, first anterior to neural spine of first pre-caudal vertebrae, second and third, between that spine and second neural spine of second pre-caudal vertebrae (Fig. 4 , Suppl. material 1: Table S3).

Caudal skeleton. Includes hypural complex and 20-24 caudal rays. This complex has five vertebral elements, CP1, CUI, and CUII or urostyle (all fused), CP2 and CP3. This last element has HEM3 that can support one or two HPCR and a NEU3 that can be free or support up to two EPCR. The CP2 is articulated with HEM2, which can be free or articulated with up to two HPCR or one or two HC = R. Likewise, CP2 on its upper side almost converges with bone E1 that is free or articulated with EPCR or ECR. The complex CP1 + CUI + CUII, is articulated on its lower side with four elements, PH and HI, which are articulated with two to four HCR each, the HII, which is articulated with one or two HCR and the HIII, which can support two or three ECR. Complex CP1 + CUI + CUII articulated on its anterior side with bone HIV, which in turn can support two to five ECR. On its upper side this complex is articulated with the ES bone that is fused with HV and can support between one to three ECR. Above HV, and always separated from Complex CP1 + CUI + CUII, E2 is positioned, which can be found without rays or an EPCR or ECR. Next and always separated from the E2, E1 is found which along its upper side only supports an EPCR and on the lower edge may be articulated and even fused with NEU2. Finally, NEU3 is observed, originating along the upper edge of CP3, which can be free or articulated with up to two EPCR (Fig. 5 , Suppl. material 1: Table S4).

Color in alcohol. The background color varies from dark yellow to dark brown; chest color varies from pale to dark brown; abdomen whitish. Operculum and cheek pale brown. Snout and forehead chestnut. Sides of the body with irregular vertical bars (chestnut or pale brown) sometimes difficult to see, of different widths, individually variable. Sometimes with pattern of 1-3 pale and dark vertical bars, normally with pale, lambda-shaped bars; central part of these bars is usually divided at level of abdomen, forming lambda (λ) figure with bases extending to pelvic fins. Dorsal and anal fins pale or dark brown with paler edges on both. Caudal fin dark brown, darker on base, always with black ocellus surrounded by narrow white or grey ring, placed in superior part of caudal-fin base, and marginally extending onto caudal peduncle. Pectoral and pelvic fins hyaline. Dorsal fin without rings or ocelli (Fig. 3 ).

Color in life. Sexual dimorphism not observed. Ventrum pale grey, chest dark grey, abdomen whitish, operculum and cheek grey to brown, snout and forehead chestnut, underside of head dark grey with greyish or greenish tinge over chestnut. Sides of body with barely visible irregular vertical bars (chestnut or dark grey) of different widths and patterns, which may vary from one individual to another. Wide vertical bar of dark brown color crosses central part of body and reaches spinous portion of anal fin. Central part of said bar usually divided at level of abdomen, forming lambda (λ) shape with bases extending to pelvic fins. Posterior side of the body with abundant iridescent orange spots that can appear longitudinally. Dorsal and anal fins dark brown with paler edges. Caudal fin dark grey, darker on base. Always with black ocellus surrounded by orange or yellow ring that reaches center of lateral line of caudal fin and extends onto caudal peduncle. Pectoral fins hyaline, dorsal and pelvic fins without spots or ocelli (Fig. 8a ).

Molecular analysis.

We amplified 612 bp of the COI gene for the 24 Astronotus specimens used for genetic analyses. The addition of sequence data (58 sequences) of Colatreli et al. (2012) and the sequences obtained in GenBank (20 sequences) increased this dataset to 102 specimens. This alignment was then reduced to a total of 22 unique haplotypes of Astronotus plus two haplotypes of Cichla ocellaris as outgroups. Sequence length varied from 468 to 664 bp, with a mean sequence length of 626 bp; 23 sites were parsimony-informative. No indels were observed. No internal stop codons were found. All Astronotus species ( A. ocellatus , A. crassipinnis , and A. mikoljii sp. nov.) and additional suggested distinct lineages ( Astronotus sp. “Jurua”, Astronotus sp. “East”, and Astronotus sp. “Negro”) shows reciprocal monophyly in the maximum credibility tree, with high posterior probability support (≥ 0.95) (Fig. 9 ).

All five single-locus species delimitation methods delimited Astronotus mikoljii sp. nov. as a distinct lineage and, overall, the only discrepancy between the methods occurred in the method bGMYC, which identified A. crassipinnis and Astronotus sp. “East” as a single lineage. The maximum intraspecific distance within A. mikoljii sp. nov. was 0.163%, while minimum inter-specific distance was 0.98% (Table 4 ). The lineage Astronotus sp. “Negro” is the closest lineage to A. mikoljii sp. nov. The mean genetic distance between A. mikoljii sp. nov. and the currently valid species ( A. crassipinnis and A. ocellatus ) had values of 1.75% and 2.15%, respectively (Table 5 ). A total of three diagnostic sites segregates A. mikoljii sp. nov. from A. ocellatus and A. crassipinnis (Table 4 ).

Multivariate analysis.

The Canonical Discriminant Analysis (CDA) using morphometric data of the sagitta otoliths clearly identified three groups corresponding to each of the described species of the genus Astronotus (Fig. 10 ). A high level of successful classification among the species was obtained using the jack-knife procedure, reaching a value ± 90% in both cases (Suppl. material 1: Table S5). In this statistical analysis, including the measurements on the geometric shape of the sagitta otoliths separated A. mikoljii sp. nov. from A. ocellatus and A. crassipinnis .

Etymology.

The specific name is given to honor Mr. Ivan Mikolji, Venezuelan explorer, artist, author, underwater photographer, and audiovisual producer, in recognition for being a tireless and enthusiastic diffuser of the biodiversity and natural history of freshwater fishes, conservation of aquatic ecosystems of Venezuela and Colombia, and for logistic support for this work. Since 2020, Ivan Mikolji has been recognized as Associate Researcher of the Museo de Historia Natural La Salle, from the Fundación La Salle de Ciencias Naturales, in Caracas, Venezuela.

Distribution.

Astronotus mikoljii sp. nov. is distributed in all parts of the lower Orinoco River basin (Fig. 7 ), along the floodplain of its main channel and in the drainages of the following rivers (or sub-basins): Atabapo, Inírida, Guaviare, Vichada, Bita, Meta, Tomo, Arauca, Apure, Caura, Morichal Largo and Delta, in Venezuela and Colombia ( Fowler 1911; Novoa and Ramos 1978; Kullander 1981; Novoa et al. 1982; Román 1985; Novoa 1986; Román 1988; Winemiller 1989a, b, 1990; Lasso and Castroviejo 1992; Monente 1992; Machado-Allison 1993; Lasso et al. 1999; Mojica 1999; Ponte et al. 1999; Lasso and Machado-Allison 2000; Lasso et al. 2003a, b, c, 2004; Campo 2004, Lasso 2004; Machado-Allison 2003; Antonio and Lasso 2004; Taphorn et al. 2005; Galvis et al. 2007; Marcano et al. 2007; Lasso et al. 2009a, b; Brito et al. 2011; Lasso et al. 2011a, b; 2014; Echeverría and Machado-Allison 2015; Ortega-Lara 2016; DoNascimiento et al. 2017; Machado-Allison et al. 2018; Winemiller et al. 2018). It also occurs in the Gulf of Paria basin ( Caño La Brea, Forest Reserve of Guarapiche, sub-basin San Juan River, EBRG 5055) in Venezuela ( Lasso et al. 2010). It has been introduced in other watersheds of Venezuela such as Lago de Valencia and in reservoirs of the Mar Caribe basin (drainages of the Unare, Tuy, Coro and San Juan rivers (Isla de Margarita)) ( Luengo 1963; León 1966; Cervigón 1983; Ginéz and Olivo 1984; Ginéz et al. 1984).

Ecology.

Astronotus mikoljii sp. nov. usually inhabits the middle and lower reaches of the Orinoco River and the Gulf of Paria basin, at altitudes not exceeding 250 m a.s.l. (Fig. 8b ). It can be found in either lotic or lentic water bodies, large or small rivers, culverts, lagoons, and floodplains, with white, clear, and black waters (sensu Sioli 1965). In the Orinoco River Delta, it lives in slow-flowing channels and flooded forests, while in the middle Orinoco region; it has only been captured in flood and floodplain lagoons, on both banks of the river ( Novoa et al. 1982; Novoa 1986). In its first stages of development, it is associated with floating vegetation and semi-rooted plants formed mainly in grasses and water hyacinth ( Paspalum repens , Eichhornia crassipes ). In the adult phase they are located in riparian zones, generally among grasses and sedges ( Machado-Allison 1993; Lasso 2004; Lasso et al. 2011b; Echeverría and Machado-Allison 2015). Part of the type material was captured in the flooded savannah of a minor tributary of the Arauca River, in the floodplains of Apure State, Venezuela (Fig. 8b ). During sampling, the body of water was almost stagnant and the water temperature was 27 °C with abundant aquatic vegetation and muddy bottom.

This species was probably negatively impacted by the invasion of the Orinoco River Basin by transferred invasive cichlid Caquetaia kraussii (Steindachner, 1878) ( Royero and Lasso 1992; Señaris and Lasso 1993; Lasso and Machado-Allison 2000). For example, in one lagoon in the Portuguesa River drainage between Guanare and Guanarito, where one of the authors (DCT) commonly collected A. mikoljii sp. nov. (on many occasions over many years during student field trips from 1978 to 1988) it is now absent, having been completely replaced by C. kraussii .

Common names.

In Spanish and indigenous local languages, names which are known for Astronotus mikoljii sp. nov. in Venezuela are pavona, vieja, cupaneca, Oscar, mijsho ( Kariña), boisikuajaba (Warao), hácho ( Pumé = Yaruro), phadeewa, jadaewa ( Ye’Kuana = Makiritare), perewa, parawa ( Eñepá = Panare), yawirra ( Kúrrim = Kurripako), kohukohurimï, kohokohorimï, owënawë kohoromï” (Yanomami = Yanomamï) ( Barandiarán 1962; Mago 1967, 1970c; Novoa et al. 1982; Obregón et al. 1984; Román 1985; Novoa 1986; Román 1988; Bedoya 1992; Mattei-Müller et al. 1994; Lasso and Machado-Allison 2000; Mosonyi 2002; Machado-Allison 2003; Vispo and Knab-Vispo 2003; Mattei-Müller and Serowe 2007; Brito et al. 2011) and pavo real, carabazú, Oscar, mojarra, mojarra negra, eba (Puinave), Itapukunda (Kurripako), uan (Tucano) in Colombia ( Sánchez 2008). The suggested common name for this species in the aquarium hobby is “Mikolji’s Oscar" in English, "Oscar de Mikolji ‘’ in Spanish.

Figures

Figure 3. Astronotus mikoljii sp. nov., preserved holotype MCNG 56677 (240.12 mm SL), Venezuela., Estado Apure, Municipio Pedro Camejo in a small stream tributary of Arauca River. Photograph: Ivan Mikolji.

Figure 4. Radiographs of paratypes of Astronotus mikoljii sp. nov. and details of the supraneural bones A MHNLS 198 (116.7 mm SL) B MHNLS 26123 (140.4 mm SL) C MHNLS 24054 (227.5 mm SL). Scale bars: 10 mm.

Figure 5. Radiographs of the caudal skeleton in Astronotus species showing magnified details A A. mikoljii sp. nov. (MHNLS 24059, 205.5 mm SL) B A. crassipinnis INPA-ICT 33889 (204.3 mm SL) C A. ocellatus USNM 284442 (79.6 mm SL). Abbreviations: hypurapophysis (PP) of parahypural bone (PH), epurals (E 1 - E 2) and neural spine (NEU 2, diastema (D), preural centrum (CP), epaxial caudal rays (ECR), hypaxial caudal rays (HCR), epaxial procurrent caudal rays (EPCR) hypaxial procurrent caudal rays (HPCR). Scale bars: 2 mm.

Figure 6. Left sagitta otoliths (medial view) of A Astronotus mikoljii sp. nov. B A. crassipinnis C A. ocellatus. Scale bars: 1 mm.

Figure 7. Map showing all the sites sampled in this study. The circles represent sampling localities based on specimen records used for morphological analyses, the squares represent sampling localities of the genetic material analyses, and the stars represent the type locality of each species. The colors represent the consensus of the species delimitation methods. Astronotus mikoljii sp. nov. (red), A. crassipinnis (green), A. ocellatus (blue), Astronotus sp. " East " (yellow), Astronotus sp. " Jurua " (orange), and Astronotus sp. " Negro " (brown).

Figure 8. Astronotus mikoljii sp. nov. A live coloration of specimens collected with holotype B Natural shallow pond and type locality in floodplain of Arauca River Venezuela. Photographs: Ivan Mikolji.

Figure 9. Maximum clade credibility tree from 9,000 posterior trees generated using BEAST 2.6. Dataset comprised 22 unique haplotypes (from a total of 102) of Astronotus COI sequences. Bayesian posterior probabilities above 0.95 are shown as dark nodes. Species delimitations are shown by method as colored boxes. The number of collapsed individuals is indicated in parentheses and outside of it the locations where they were sampled. The scientific name of the new species is red. The figure was created in R 4.1.1 using the package ' ggtree' and the final graphic in Inkscape.

Figure 10. Plot of scores of Canonical Variants Analysis (CVA), from comparative sagitta otoliths morphometric data of Astronotus mikoljii sp. nov. (red crosses), A. ocellatus (blue squares), and A. crassipinnis (green triangles).