Eigenmannia sayona, Peixoto & Waltz, 2017

Peixoto, Luiz A. W. & Waltz, Brandon T., 2017, A new species of the Eigenmannia trilineata (Gymnotiformes: Sternopygidae) species group from the río Orinoco basin, Venezuela, Neotropical Ichthyology 15 (1), No. e 150199, pp. 1-8 : 2-6

Eigenmannia sayona , new species

urn:lsid:zoobank.org:act:F127F01B-AC21-4D1B-BC4F-EBAB9EA64854

Fig. 1

Holotype. MZUSP 96497, 131.8 mm LEA, Venezuela, Bolivar, Cedeño, río Parguaza, río Orinoco basin, near the community of Puente Parhueña , 5°53’30”N 67°24’14”W, 19 Jul 2004, M. de Pinna & C. Oliveira.

Paratypes. All from Venezuela. Bolivar : FMNH 130239 , 1 , 95.4 mm LEA ; MPEG 33926 , 1, 103.7 mm LEA ; MZUSP 119711 , 6 + 2 c&s, 27.8-116.2 mm LEA, collected with the holotype . MZUSP 96465 , 1, 116.2 mm LEA, Caicara del Orinoco, río Orinoco, Laguna de Castilleros , 7°30’51”N 66°09’20”W, 22 Jul 2004, M. de Pinna & C. Oliveira .

Non-types. All listed specimens were directly preserved in alcohol (except USNM specimens). Venezuela. Apure: USNM 260225 , 13 , 47.1-68.5 mm LEA, Caño Caicara . Bolivar: LBP 2225, 1, 54.7 mm LEA, Caicara del Orinoco, río Orinoco, Laguna de Castilleros. LBP 2311, 3, 91.1-107.5 mm LEA, Cedeño , río Orinoco , río Parguaza. LBP 3083, 4, 53.6-65.1 mm LEA, Caicara del Orinoco , río Orinoco. LBP 9976, 3, 57.7-89.9 mm LEA (two specimens measured; one specimen damaged), Caicara del Orinoco , río Orinoco , Laguna de Castilleros .

Diagnosis. Eigenmannia sayona can be distinguished from its congeners, except species of the E. trilineata species group, by the presence of a superior midlateral stripe (vs. absence). Eigenmannia sayona can be differentiated from congeners in the E. trilineata species group by the ossification of the first basibranchial ( Fig. 2) (vs. unossified). The new species can be distinguished from congeners in the E. trilineata species group, except E. correntes , by the unique dentition pattern of the premaxilla, 17 teeth distributed in three irregular rows ( Fig. 3) (vs. eight to 12 teeth distributed in two rows in E. antonioi ; 18-29 teeth distributed in three or four rows in E. besouro ; 24 or 25 teeth distributed in four rows in E. desantanai ; nine or ten teeth distributed in two rows in E. guairaca ; 22-24 teeth distributed in four rows in E. matintapereira ; 16 teeth distributed in three rows in E. microstoma ; eight to ten teeth distributed in two rows in E. muirapinima ; 13-16 teeth distributed in three rows in E. pavulagem ; 31-33 teeth distributed in four rows in E. trilineata ; 25 or 26 teeth distributed in four rows in E. vicestespelaea ; 35 or 40 teeth distributed in five rows in E. waiwai ). The new species can be differentiated from E. besouro , E. correntes , E. desantanai , E. guairaca , E. matintapereira , E. microstoma , E. trilineata , E. vicentespelaea , and E. waiwai by the dentition pattern of the dentary, with teeth increasing abruptly in size from the sixth or seventh tooth ( Fig. 4) (vs. dentary teeth similar in size). Eigenmannia sayona can be further distinguished from other species in the E. trilineata species group, except E. antonioi , E. matintapereira , E. microstoma , E. muirapinima , E. pavulagem , and E. trilineata , by the number of anal-fin rays, 198-217 (vs. 150-181 in E. besouro ; 143-164 in E. correntes ; 170-196 in E. desantanai ; 151-170 in E. guairaca ; 169- 191 in E. vicentespelaea ; 167-195 in E. waiwai ). The new species can be distinguished from E. besouro , E. desantanai , E. muirapinima , E. vicentespelaea , and E. waiwai by the number of tooth rows on the endopterygoid, 1 (vs. 2). The new species can be differentiated from E. besouro , E. correntes , E. desantanai , E. guairaca , E. microstoma , and E. trilineata by the number of precaudal vertebrae, 13 (vs. 14; 14; 11-12; 15; 14-15; and 14, respectively). Eigenmannia sayona can be differentiated from E. antonioi , E. correntes , E. desantanai , E. guairaca , E. muirapinima , E. pavulagem , E. vicentespelaea , and E. waiwai by the length of the anterodorsal process of maxilla being equal to the width of the posterior nostril ( Fig. 5) (vs. equal to 1.5 times the width of the posterior nostril in E. waiwai ; or approximately 20-50% of the width of the posterior nostril in aforementioned species - Fig. 4b of Peixoto et al., 2015). Eigenmannia sayona can be further differentiated from E. besouro , E. correntes , E. matintapereira , E. trilineata , and E. waiwai by the depth of the posterodorsal expansion on infraorbitals 1+2, approximately equal to the total length of infraorbitals 1+2 ( Fig. 6) (vs. less than 50% of the length of infraorbitals 1+2). The new species differs from E. besouro , E. correntes , E. vicentespelaea and E. waiwai by possessing a terminal mouth (vs. subterminal). The new species can be distinguished from E. microstoma and E. trilineata by the suborbital depth, 20.6-26.8% HL (vs. 29.9-40.8%; and 32.5-46.6%, respectively). Eigenmannia sayona can be distinguished from E. microstoma and E. vicentespelaea by the number of scales above lateral line, 9-10 (vs. 11-15; and 7-8, respectively). Eigenmannia sayona can be differentiated from E. matintapereira , E. trilineata , and E. vicentespelaea by the number of pectoral-fin rays, ii,12-13 (vs. ii,16-17; ii,14- 15; and ii,15-17, respectively). Eigenmannia sayona can be differentiated from E. matintapereira , E. muirapinima , and E. waiwai , by oral width, 18.7-21.7% HL (vs. 12.6-16.1%; 13.2-18.1%; and 9.5-14.6%, respectively). Eigenmannia sayona can be further distinguished from E. guairaca and E. waiwai by orbital diameter, 17.3-22.4% HL (vs. 11.4-15.0%; and 22.6-28.8%, respectively). Eigenmannia sayona differs from E. guairaca by postorbital distance, 50.1-55.5% HL (vs. 56.8-61.9%). Eigenmannia sayona can be distinguished from E. matintapereira by the pectoral-fin coloration hyaline (vs. uniformly dark or with a median blotch); by the anal-fin distal margin coloration hyaline (vs. uniformly darkened); and by the posterior nostril to orbit distance, 6.9-9.9% HL (vs. 2.5-6.6%). The new species can be further distinguished from E. vicentespelaea by the snout length, 22.5-28.3% HL (vs. 28.6-36.8%).

Description. Species of small/medium size, maximum length recorded 131.8 mm TL. Morphometric data is presented in Tab. 1. Body elongate and laterally compressed. Dorsal profile of body nearly straight or slightly convex from posterior margin of head to vertical line through middle of anal fin, and then posterodorsally angled in a straight line to distal portion of caudal filament. Ventral profile of body slightly concave along anterior half of abdominal cavity; then posteriorly angled to last anal-fin ray. Ventral profile of caudal filament straight. Greatest body depth at vertical line through distal margin of pectoral fin. Head laterally compressed, greatest width at posterior opercular region and greatest depth at posterior margin of supraoccipital. Dorsal profile of head slightly convex or nearly straight from upper lip to vertical through branchial opening. Ventral profile of head slightly concave from anterior margin of lower lip to branchial opening. Snout rounded in profile. Mouth terminal. Upper lip slightly overlapping lower lip or lips equal in length. Premaxilla teeth 17(2) in three rows [outermost row with 4(2) teeth; median row with 6(2); innermost row with 7(2) teeth, Fig. 3]. Maxilla with sickleshaped anterodorsal process equal to the width of posterior nostril. Dentary teeth 19(1) or 26(1) in two irregular rows [outermost row with 11(1) or 14(1); innermost row teeth, 8(1) or 12(1), Fig. 4]. Dentary teeth increasing abruptly in size from the sixth or seventh tooth of outermost row towards rictus. Coronomeckelian bone equal to 30% of length of Meckel’s cartilage. Endopterygoid teeth 8(1) or 9(1) in a single row. Mouth rictus at vertical line through anterior nostril or in region between nostrils. Anterior nares tubular, posterior margin at vertical line through posterior margin or middle portion of rictus. Posterior nares elliptical, non-tubular, and closer to anterior margin of eye than tip of snout. Eye approximately circular, covered by skin, lateral on anterior half of head. Antorbital and infraorbitals 1-4 enlarged partial cylinders with slender osseous arches. Fifth and sixth infraorbitals slender and tubular. Depth of posterodorsal expansion on infraorbitals 1+2 equal to total length of infraorbitals 1+2 ( Fig. 5). Branchial opening moderately elongate. Branchial membrane joined with isthmus. Anus and urogenital papilla shifting anteriorly during ontogeny, from vertical line through posterior portion of opercle in juveniles [minimum examined 47.1 mm LEA] to vertical line through posterior portion of eye in adults. Anus and urogenital papilla at vertical line through posterior margin of eye in mature specimens.

Cycloid scales present from posterior margin of head to distal portion of caudal filament. Lateral line complete, 122(2), 124(1), 125(2), 127(2), 128*(1), 132(1), 134(2) or 136(1) perforated scales to vertical line through end of anal fin (N=12). Longitudinal series of scales above lateral line at distal margin of pectoral fin, 9*(5), 10(7) or 11(4). Scales over anal-fin pterygiophores approximately one-half size of others.

Pectoral-fin rays, ii,12*(6) or ii,13(11); distal margin slightly rounded; tip reaching vertical through 16 th to 27 th anal-fin ray. Anal-fin origin posterior to vertical line through pectoral-fin base; total anal-fin rays, 198*-217 (N=14); distal margin of anal fin slightly convex. Caudal filament cylindrical, tapering gradually distally, relatively short and approximately 40% of LEA in mature specimens.

Precaudal vertebrae 13(2). Anterior vertebrae 10(1) or 12(1), transitional vertebrae 1(1) or 3(1). Displaced hemal spines 3(2).

indicates the anterodorsal process. Scale bar: 0.5 mm. Coloration in alcohol. Background color dark yellow. Dorsal region of head dark yellow; gradually lighter ventrally with sparse chromatophores in ventral portion. Lips and suborbital region light brown. Dorsal region of body dark brown, gradually lighter ventrally towards region overlying anal-fin pterygiophores. Four dark longitudinal stripes along body. Lateral-line stripe thin, one or two scales deep, extending from first perforated lateral-line scale to distal portion of caudal filament. Superior midlateral stripe thick, two scales deep, tapering approximately from vertical line between base of 20 th to 28 th anal-fin ray to posterior second-third of body in specimens. Inferior midlateral stripe moderately thick, two or three scales deep, extending from vertical line approximately between base of 25 th to 30 h anal-fin ray to posterior-most one-third of body. Anal-fin base stripe thick, two scales deep, extending from vertical between base of first anal-fin ray to last anal-fin ray. Pectoral and anal fins hyaline, scattered tiny chromatophores on interradial membranes.

Geographic distribution. Eigenmannia sayona is known from río Orinoco basin, from río Parguaza, río Apure, and Laguna de Castilleros, Venezuela ( Fig. 7).

Etymology. The specific epithet “ sayona ” is assigned to the new species in reference to “La Sayona”, a spirit of philanderous vengeance in Venezuelan lore. A noun in apposition.