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| Astronotus mikoljii Lozano, Lasso-Alcalá, Bittencourt, Taphorn, Perez & Farias, 2022 |
Abstract
Based on morphological and molecular analysis of Astronotus species, a new species is described from the Orinoco River and Gulf of Paria basins in Venezuela and Colombia. Morphologically, it differs from Astronotus crassipinnis and Astronotus ocellatus in pre-orbital depth, caudal peduncle depth, head width, and caudal peduncle length, with significant differences in average percentage values. Osteologically, it differs from the two described species by lacking a hypurapophysis on the parahypural bone (hypural complex) and having two or three supraneural bones. Another characteristic that helps diagnose the new species is the morphology of the sagitta otolith, which is oval with crenulated dorsal and ventral margins and a rounded posterior edge. Genetically, the new species is distinct from all the other lineages previously proposed for the genus, delimited by five single locus species delimitation methods, and also has unique diagnostic nucleotides. Phylogenetic analyses support the monophyly of the new species as well as all other species/lineages. Astronotus species have considerable genetic, anatomical, and sagitta otolith shape differences, but have few significant traditional morphometric and meristic differences, because there is high variability in counts of spines, soft dorsal-fin rays, and lateral-line scales. It is clear that this new species is genetically and anatomically differentiated from all other species within the genus, and deserves recognition as a new valid species.
Keywords: DNA, fish, freshwater, morphometrics, osteology, sagitta otoliths, taxonomy
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| 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. |
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| 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. |
Astronotus mikoljii sp. nov.
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).
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.
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.
Alfredo Perez Lozano, Oscar M. Lasso-Alcalá, Pedro S. Bittencourt, Donald C. Taphorn, Nayibe Perez and Izeni Pires Farias. 2022. A New Species of Astronotus (Teleostei, Cichlidae) from the Orinoco River and Gulf of Paria Basins, northern South America. ZooKeys. 1113: 111-152. DOI: 10.3897/zookeys.1113.81240
