Eigenmannia matintapereira, Peixoto & Dutra & Wosiacki, 2015

Peixoto, Luiz Antônio Wanderley, Dutra, Guilherme Moreira & Wosiacki, Wolmar Benjamin, 2015, The Electric Glass Knifefishes of the Eigenmannia trilineata species-group (Gymnotiformes: Sternopygidae): monophyly and description of seven new species, Zoological Journal of the Linnean Society 175 (2), pp. 384-414 : 396-398

EIGENMANNIA MATINTAPEREIRA SP. NOV.

( FIGS 1A , 4A , 11 , 12 ; TABLE 1)

Diagnosis: Eigenmannia matintapereira differs from other species in the E. trilineata species group by the pectoral-fin, which is uniformly dark or has a dark medial blotch (versus hyaline), and the anal-fin coloration of a uniformly darkened (versus hyaline). Eigenmannia matintapereira can be further distinguished from species of the E. trilineata species group, except E. vicentespelaea , by the ii,16–17 pectoral-fin rays (versus ii, 13–14 in E. antonioi and E. pavulagem ; ii, 11–12 in E. guairaca and E. muirapinima ; ii, 12–14 in E. desantanai ; ii, 14–15 in E. microstoma and E. trilineata ; and ii, 13–15 in E. waiwai ). Eigenmannia matintapereira can be distinguished from E. vicentespelaea by the terminal mouth (versus subterminal); the number of total anal-fin rays 216– 222 (versus 169–191); between ten and 12 scales above lateral line (versus seven or eight); and 130–145 scales to the end of anal fin (versus 110–125). Eigenmannia matintapereira also differs from species allocated to the E. trilineata species-group, except E. trilineata , by the number of total anal-fin rays 216–222 (versus 166– 207 in E. antonioi ; 170–198 in E. desantanai and E. muirapinima ; 151–170 in E. guairaca ; 173–207 in E. microstoma ; 176–201 in E. pavulagem ; 197–201 in E. vicentespelaea ; and 167–195 in E. waiwai ). Eigenmannia matintapereira can be distinguished from E. trilineata by the suborbital depth 18.2–26.1% HL (versus 32.5–46.6%); the orbital diameter 21.6–28.8% HL (versus 15.3–21.6%); and the ii,16–17 pectoral-fin rays (versus ii,14–15).

Description: Morphometric data in Table 1. Body elongate and laterally compressed. Dorsal profile of body straight from rear of head to vertical through middle of anal fin; then posteroventrally aligned with distal portion of caudal filament. Ventral profile of body slightly concave or posteroventrally aligned along anterior half of abdominal cavity; then posterodorsally aligned with last anal-fin ray. Ventral margin of caudal filament straight. Greatest body depth at vertical through distal margin of pectoral fin.

Head laterally compressed with greatest width at opercular region and greatest depth at posterior margin of supraoccipital. Dorsal profile of head posterodorsally aligned from upper lip to posterior margin of orbit, concave to vertical through posterior margin of opercle, and straight to vertical through branchial opening. Ventral profile of head posteroventrally aligned from anterior margin of lower lip to branchial opening. Snout rounded in profile. Mouth terminal. Upper lip slightly overlapping lower lip or anterior profile of lips in same vertical. Premaxillary teeth 22(1) or 24(1) distributed in four rows [outermost row with 3(1) or 4(1) teeth; second row with 5(1) or 6(1) teeth; third row with 7(2) teeth; innermost with 6(1) or 8(1) teeth]. Maxilla with sickle-shaped anterodorsal process equal to width of posterior nostril. Dentary teeth 25(1) or 27(1) distributed in two series [outermost row with 15(1) or 16(1) teeth; innermost row with 9(1) or 11(1) teeth]. Dentary teeth similar in size. Coronomeckelian bone equal to 20% of length of Meckel’s cartilage. Endopterygoid with 9(1) or 12(1) teeth in one or two series. Mouth rictus at vertical through anterior nostril or in region between nares. Anterior naris tube-like, with posterior margin located at vertical through posterior margin of rictus or in median portion of rictus. Posterior naris elliptical, without tube, located closer to anterior margin of eye than snout tip. Eye approximately circular, covered by skin, laterally located on anterior half of head. Antorbital and infraorbitals 1–4 in form of enlarged, partial cylinders with slender osseous arches. Fifth and sixth infraorbitals slender and tubular. Depth of posterodorsal expansion on infraorbitals 1 + 2 equals 50% length of infraorbitals 1 + 2. Branchial opening moderately elongate. Branchial membrane joined to isthmus. Anus and urogenital papilla shifting anteriorly ontogenetically. Anus and urogenital papilla at vertical through middle of, or posterior margin of, orbit in mature specimens.

Cycloid scales present from immediately posterior to head to distal portion of caudal filament. Lateral line complete, with 130(2), 131(1)*, 132(2), 136(3), or 145(2) perforated scales to vertical through end of anal fin. Longitudinal series of scales above lateral line, 10(3), 11*(4), or 12(3). Scales over anal-fin pterygiophores approximately one-half the size of others.

Pectoral-fin rays, ii,16(4) or ii,17*(6). Distal margin of pectoral fin approximately straight. Tip of pectoral fin reaching vertical through base of anal-fin rays 28– 35. Anal-fin origin at vertical on base of first pectoralfin ray; total anal-fin rays, 216–222 (206*, N = 10; Table 2). Distal margin of anal fin straight. Caudal filament cylindrical, tapering gradually distally; relatively short and approximately 50% LEA in mature specimens.

Precaudal vertebrae 13(2). Anterior vertebrae 9(1) or 10(1). Transitional vertebrae 3(1) or 4(1). Displaced haemal spines 2(1) or 3(1).

Coloration in alcohol: Background colour dark. Head dark dorsally and gradually becoming lighter ventrally. Lips and suborbital region dark. Body dark dorsally and gradually becoming lighter to region overlying anal-fin pterygiophores. Specimens up to 80.0 mm LEA, with background colour yellowish. Four longitudinal dark stripes along body. Lateral-line stripe thin, one scale deep, extending from first perforated lateralline scale to distal portion of caudal filament. Superi- or medial stripe thick, between three and five scales deep, tapering from vertical between base of anal-fin rays 25–31 to posterior one-third of body. Inferior medial stripe thick, two scales deep, extending from vertical between base of anal-fin rays 27–30 to posterior onethird of body. Anal-fin base stripe thick, six or seven scales deep, extending from vertical through base of first to vertical through base of last anal-fin ray. Stripes in specimens up to 80.0 mm LEA, less conspicuous. Pectoral fin uniformly darkened or with dark blotch in median portion, distal margin hyaline. Anal fin uniformly dark. Pectoral and anal fins hyaline, with scattered tiny chromatophores on interradial membranes in juveniles up to 80.0 mm LEA.

Distribution: Eigenmannia matintapereira sp. nov. is known from Rio Uneiuxi and Rio Urubaxi, tributaries of the Rio Negro, Amazonas, Brazil ( Fig. 6 ).

Etymology: The epithet ‘ matintapereira ’ is a reference to ‘Matinta Pereira’, the mythical figure that haunts people in search of tobacco and coffee in northern Brazil. According to reports, its appearance is marked by a blackened aspect, an allusion to the colour pattern present in Eigenmannia matintapereira sp. nov.

Remarks: Eigenmannia matintapereira sp. nov. has an intensely dark background colour, a pectoral fin that is black or with a dark blotch, and an anal fin uniformly darkened. This colour pattern is similar to that in E. nigra ; however, it can be easily distinguished from E. nigra by: the presence of four stripes along the body (versus stripes absent); 216–222 anal-fin rays (versus 231–247); body depth at the vertical through the tip of longest pectoral-fin ray, 14.1–15.0% LEA (versus 16.6– 18.9%); body depth at the vertical through first analfin ray, 11.6–12.5% LEA (versus 13.3–15.0%); orbital diameter, 21.6–28.8% LEA (versus 15.1–20.0%); and suborbital depth 18.2–26.1% HL (versus 28.9–35.2%).

Material examined

Holotype: Brazil. Amazonas : MZUSP 109618, 152.9 mm LEA, Rio Uneiuxi , Rio Negro basin, Município de Santa Isabel do Rio Negro, 0°21′45.0″ S, 65°04′13.0″ W, collected by M. Toledo-Piza, O. Oyakawa, G. Mattox, and J. Santana, 8 February 2011.

Paratypes: Brazil. Amazonas : MZUSP 117004 , 3 + 1CS, 79.7–143.6 mm LEA, collected with holotype . MZUSP 109695 , 5 + 1CS, 65.7–167.7 mm LEA, Rio Urubaxi , Rio Negro basin, 0°30′6″ S, 64°49′11″ W, collected by M. Toledo-Piza, O. Oyakawa, G. Mattox, and J. Santana, 9 February 2011 ; MPEG 963 , 1 , 91.62 mm LEA, Rio Negro , collected by M. Goulding, 24 October 1979 ; MPEG 1314 , 2 , 76.9 – 94.6 , Ilha Gavião , Rio Negro basin, collected by T. Bullock, 15 May 1967 . MZUSP 29973 , 1 , 99.7 mm LEA, Rio Arirará , collect- ed by M. Goulding, 6 October 1979 . MZUSP 29974 , 1, 123.6 mm LEA, Rio Marauiá , Rio Negro Basin, collected by M. Goulding, 13 October 1979 . MZUSP 29975 , 3 , 100 – 120.6 mm LEA (1 specimen damaged) Rio Negro , collected by M. Goulding, 18 October 1979 . MZUSP 29981 , 1, 120.3 mm LEA, Rio Negro , collect- ed by M. Goulding, 16 February 1980 .

Non-type specimens: LBP 18301, 9 , 49.1–142.3 mm LEA, Rio Negro, 0°30′5.3″ S, 64°49′12.2″ W (all specimens damaged) .

Figures

Figure 1. Scanning electron micrographs (SEMs) of infraorbitals 1 + 2, lateral view, anterior to left: A, Eigenmannia antonioi sp. nov. (MPEG 10182, 88.7 mm LEA); B, Eigenmannia matintapereira sp. nov. (MZUSP 109618, 118.3 mm LEA). Arrow indicates the posterodorsal expansion. Abbreviations: DPE, depth of the posterodorsal expansion; LIB, length of the infraorbital bones 1 + 2. Scale bar: 1 mm.

Figure 4. Schematic illustration of lateral view of maxilla: A, Eigenmannia matintapereira sp. nov. (MZUSP 109618, 118.3 mm LEA); B, Eigenmannia antonioi sp. nov. (MPEG 10182, 88.7 mm LEA). Cartilage represented by grey. Arrow indicates anterodorsal process. Scale bar: 1 mm.

Figure 6. Map of South America showing the distribution of Eigenmannia antoinoi sp. nov., Eigenmannia desantanai sp. nov., Eigenmannia guairaca sp. nov. sp. nov., Eigenmannia matintapereira sp. nov., Eigenmannia microstoma (1 = type locality), Eigenmannia muirapinima sp. nov., Eigenmannia pavulagem sp. nov. (2 = type locality), Eigenmannia trilineata (3 = type locality), Eigenmannia vicentespelaea, and Eigenmannia waiwai sp. nov. Some symbols represent more than one lot and/or locality.

Figure 11. Lateral view of Eigenmannia matintapereira sp. nov., holotype, MZUSP 109618, 152.9 mm LEA, Rio Uneiuxi, Rio Negro basin, Município de Santa Isabel do Rio Negro, Amazonas, Brazil, 0°21′45″ S, 65°04′13″ W.

Figure 12. Lateral view of head of Eigenmannia matintapereira sp. nov., holotype, MZUSP 109618, 152.9 mm LEA, Rio Uneiuxi, Rio Negro basin, Município de Santa Isabel do Rio Negro, Amazonas, Brazil, 0°21′45″ S, 65°04′13″ W.