Boehlkea weitzmani, Soares & Bertaco & Ito & Zuanon, 2017

Soares, Isabel M., Bertaco, Vinicius A., Ito, Priscila Madoka M. & Zuanon, Jansen, 2017, A new species of Boehlkea (Characiformes: Characidae: Stevardiinae) from the rio Japurá, Amazon basin, Brazil, Neotropical Ichthyology 15 (3), No. e 170026, pp. 1-38 : 1-38

Boehlkea weitzmani , new species

u r n:l s i d:z o o b a n k. o rg:a c t: 2 4 4C2 4 8 0-D 4C E -4 0 4 6- 9B7 8- 4B87C8F3995B

Figs. 1-4, Tabs. 1 and 2

Holotype. INPA 53202 , male, 33.7 mm SL, Brazil, Amazonas State , rio Japurá, stream at 500 m of the left margin of the river, 01°42’52”S 69°07’41”W, 8 Sep 2014, P. M. Ito & R. Collins.

Paratypes. Brazil, Amazonas State, rio Japurá: ANSP 203166 , 2 , 25.4-31.2 mm SL, collected with the holotye ; INPA 48539 , 1 , 27.1 mm SL, stream on left margin of the river, 01°43’8”S 69°07’38”W, 1 Sep 2014, J. Zuanon, I. M. Soares, P. M. Ito ; INPA 48540 , 9 , 16.6-30.2 mm SL (2, 23.4-30.2 mm SL), collected with the holotype ; INPA 48541 , 7 , 14.0- 34.8 mm SL (3, 31.1-34.8 mm SL; 1 c&s, 32.8 mm SL), stream on left margin of the river, 01°42’52”S 69°02’55”W, about 400 m, 31 Aug 2014, J. Zuanon, I. M. Soares, P. M. Ito & R. Collins ; INPA 48542 , 4 , 23.8-28.5 mm SL (2, 24.8-28.5 mm SL), stream on left margin of the river, 01°43’08”S 69°07’37”W, 7 Sep 2014, P. M. Ito & R. Collins ; INPA 48543 , 5 , 17.8-30.9 mm SL (2, 25.8-30.9 mm SL; 1 c&s, 26.7 mm SL), stream on left margin of the river, about 400 m of the access track, 01°50’56”S 69°01’45”W, 6 Sep 2014, P. M. Ito & R. Collins ; INPA 48544 , 15 , 16.6 - 25.0 mm SL (4, 22.3-25.0 mm SL; 2 c&s, 26.4-29.4 mm SL), about 500 m of access track, on left track, right margin of the river, 01°42’52”S 69°02’51”W, 30 Aug 2014, J. Zuanon, I. M. Soares & P. M. Ito ; INPA 48545 , 8 , 22.7-31.7 mm SL (4, 25.5-31.7 mm SL), stream on left margin of the river, 01°42’43”S 69°07’10”W, 1 Sep 2014, J. Zuanon, I. M. Soares, P. M. Ito & R. Collins ; MCN 19980, 2 , 30.3- 31.2 mm SL, stream on left margin of the river, about 400 m of the access track, 01°50’56”S 69°01’45”W, 6 Sep 2014, P. M. Ito & R. Collins ; MCN 19981, 2 , 24.3-30.6 mm SL, about 500 m of access track, on left track, right margin of the river, 01°42’52”S 69°02’51”W, 30 Aug 2014, J. Zuanon, I. M. Soares & P. M. Ito ; MCN 19982, 1 , 28.5 mm SL, stream on left margin of the river, 01°42’43”S 69°07’10”W, 1 Sep 2014, J. Zuanon, I. M. Soares, P. M. Ito & R. Collins ; MZUSP 117172 , 1 , 28.1 mm SL, about 500 m of access track, on left track, right margin of the river, 01°42’52”S 69°02’51”W, 30 Aug 2014, J. Zuanon, I. M. Soares & P. M. Ito ; USNM 432545 , 1 , 30.1 mm SL, stream on left margin of the river, 01°42’43”S 69°07’10”W, 1 Sep 2014, J. Zuanon, I. M. Soares, P. M. Ito & R. Collins .

Diagnosis. Boehlkea weitzmani is differentiated from B. fredcochui by having a complete lateral line (vs. incomplete), four rows of scales below lateral line (vs. three), presence of a conspicuous vertically elongated humeral spot (vs. absence of a humeral spot), and by lower number of branched analfin rays (17-21 vs. 22-25), and from B. orcesi (sensu Bertaco, Malabarba, 2010) by the higher number of maxillary teeth (13-14 vs. 5-12), greater head length (27.9-29.9% vs. 24.3- 27.5% of SL), and by the color pattern (basal half of dorsal fin, distal portion of pelvic fin, lower caudal-fin lobe and anal-fin with black chromatophores vs. unpigmented fins).

Description. Morphometric data for Boehlkea weitzmani presented in Tab. 1. Body compressed and elongate; greatest body depth located anteriorly to dorsal-fin origin. Dorsal profile of head convex from tip of snout to anterior naris, straight from latter point to tip of supraoccipital spine. Dorsal profile of body slightly convex from tip of supraoccipital spine to dorsal-fin origin; slanted from this point to adiposefin origin and slightly concave along caudal peduncle. Ventral profile of body convex from tip of lower jaw to anal fin; slanted along anal-fin base and slightly concave along caudal peduncle.

Snout rounded. Mouth terminal; slit nearly at horizontal through middle of eye. Premaxillary teeth in two rows. Outer row with 4 * (6), 5(21), or 6(4), tricuspid teeth with central cusp slightly longer; inner row with 4 * (32) pentacuspid teeth, gradually decreasing in size from anteriormost teeth. Maxillary almost fully toothed with 5(1), 6(1), 7(5), 8(7), 9(10), 10 * (6), 11(1), or 12(1) uni- to tricuspid teeth, with central cusp longer. Three anteriormost dentary teeth larger, with five cusps, followed by a medium-sized tooth with three cusps, and 7(1), 8 * (2), 9(5), 10(4), 11(3), 12(6), 13(3), 14(2), 15(2), 16(3), or 17(1) smaller conical teeth ( Fig. 2).

Dorsal-fin rays ii,8(32); first unbranched ray smaller than half length of second unbranched ray. Dorsal-fin origin slightly posterior to body midlength and posterior to vertical through pelvic-fin origin. Adipose fin present. Pectoral-fin rays i,9 * (4), 10(20), or 11(8); pectoral-fin tip reaching pelvic-fin origin. Pelvic-fin rays i,6(31); pelvic fin reaching anal-fin origin. Anal-fin rays iii * (18), iv(13) or v(1), 17(1), 18(3), 19(12), 20 * (13) or 21(3); anal-fin origin approximately at vertical through insertion in last dorsal-fin insertion rays. Principal caudal-fin rays i,9 * (31) or i,10(1) + 8,i * (31) or 9,i(1). Dorsal procurrent caudal-fin rays 10(1), 11(2), or 12(1) and ventral procurrent caudal-fin rays 11(3) or 12(1). Caudal fin forked, lobes similar in size.

Scales cycloid. Lateral line complete, slightly curved anteriorly, with 36(2), 37(10), 38(11), 39 * (7), or 40(2) perforated scales. Longitudinal scale rows between dorsalfin origin and lateral line 5 * (30) or 6(2); longitudinal scale rows between lateral line and pelvic-fin origin 3 * (31) or 4(1). Predorsal scales row with 9(2), 10(5), 11 * (9), or 12(16) scales. Circumpeduncular scales 14 * (30). Scale sheath along anal-fin base with 13 * (3), 14(3), 15(6), 16(5), 17(7), 18(5), 19(2), or 21(1) small scales in single series, overlying almost entire length of basal portion of anal-fin rays. Small scales covering one third of base of caudal-fin lobes.

Supraneurals 5(4), “I”-shaped. Precaudal vertebrae 15(3) or 16(1); caudal vertebrae 21(2), 22(1) or 23(1); total vertebrae 36(1), 37(2), or 38(1). First gill arch with 5(3) or 6 * (25) gill-rakers on upper limb and 8(1), 9(3), 10 * (20), or 11(4) on lower limb.

and over three scale rows dorsal to lateral line. Longitudinal dark stripe along body midline, originating at end of humeral spot, extending to middle of caudal-fin rays, covering two rows of scales. Scattered dark chromatophores above anal-fin base. Distal portion of first to fourth dorsal-fin rays hyaline. Interadial membranes of dorsal fin with dense concentration of dark chromatophores, resulting in dark band. Adipose, pectoral and pelvic fins hyaline. Proximal portion of anal fin with few scattered dark chromatophores or hyaline. Distal portion of interadial membranes of anal fin with dense concentration of dark chromatophores, resulting in dark stripe-like pigmentation. Caudal fin with dark pigmentation along its lateral borders forming broad transversal stripe on both lobes. Tips of caudal-fin lobes hyaline. Middle portion of lower caudal-fin lobe with dark chromatophores forming vertical stripe-like blotch in interadial membranes along lower border without reaching tip of rays.

Color in alcohol. Overall ground color of body pale yellow. Upper jaw, anterior portion of maxilla, snout, top of head and dorsal portion of opercle with dense concentration of small dark chromatophores. Lower jaw, gular area and infraorbitals clearer. Dorsal surface of body with dark chromatophores from posterior region of supraocciptal spine to caudal peduncle, resulting in dark stripe on the dorsum. One conspicuous humeral spot vertically oriented, extending horizontally from second through third lateral-line scales, Color in life. Overall body color silvery on flanks, with dorsum light olive to yellow from snout tip to near insertion of adipose fin; ventral area silvery white. Black vertically elongated humeral blotch. Scattered melanophores forming faint band along midline just above lateral line scales of posterior half of body. Upper portion of iris red, with some small red markings also on its lower edge. Purple to bluish sheen on scales of caudal peduncle extending to the scales over caudal-fin base. Pectoral fin hyaline; pelvic fin hyaline to whitish. Adipose fin with basal two-thirds opaque white and hyaline outer edge. Dorsal, anal and caudal fins with scattered red chromatophores over interadial membranes, more pronounced on caudal-fin base ( Fig. 3).

Neotropical Ichthyology, 15(3): e170026, 2017 I. M. Soares, V. A. Bertaco, P. M. M. Ito & J. Zuanon

Sexual dimorphism. Mature males of Boehlkea weitzmani have slightly curved bony hooks on the pelvic- and analfin rays. Pelvic fin has one hook per segment, which are arranged on the distal portion of the first to fifth (rarely on the sixth) branched rays. One or two pairs of hooks per segmentlocated on the distal portions of the last unbranched anal-fin ray and up to the eighth or ninth (sometimes tenth) branched anal-fin rays.

Geographic distribution. Boehlkea weitzmani is currently known only from streams of the rio Japurá basin, a left margin tributary of the rio Solimões basin, Amazonas State, Brazil ( Fig. 4).

well oxygenated (3.49-7.8 mg /l), and with low electrical conductivity (<33.3 µS/cm). The streams were almost completely shaded by the forest canopy, and the channel substrate was predominantly composed by white silica sand and pebbles, with interspersed litter banks. Boehlkea weitzmani co-occurred in the streams with other fishes such as characids Bario steindachneri (Eigenmann, 1893) , Bryconella pallidifrons (Fowler, 1946) , Hemigrammus bellottii (Steindachner, 1882) , H. marginatus Ellis, 1911 , Knodus orteguasae (Fowler, 1943) , Moenkhausia agnesae Géry, 1965 , Tyttocharax madeirae Fowler, 1913 ; lebiasinid Pyrrhulina semifasciata Steindachner, 1876 ; heptapterid Nannoglanis fasciatus Boulenger, 1887 , and Myoglanis koepckei Chang, 1999 ; cetopsids Denticetopsis seducta Vari, Ferraris & de Pinna, 2005 , and Helogenes marmoratus Günther, 1863 ; rhamphichthyid knifefish Gymnorhamphichthys rondoni (Miranda Ribeiro, 1920) , and some cichlids Aequidens pallidus (Heckel, 1840) , and Bujurquina cf. robusta Kullander, 1986 . The rio Japurá region still has large areas of intact forests, favoring the conservation of the fish fauna that depends on the input of organic material from riparian vegetation.

Etymology. The specific epithet weitzmani is a patronym in honor of Stanley H. Weitzman, in recognition of his remarkable contributions to the knowledge of the characiform taxonomy.

Ecological notes. Specimens of Boehlkea weitzmani were collected in small upland forest streams (width: 1.1-2.7 m; depth: 0.07-0.33 m; current velocity 0.20-0.42 m /s) draining to both margins of the rio Japurá ( Fig. 5). The water was clear to yellowish, acidic (pH <6.6), cool (23.8-25.3°C), Conservation status. Considering the overall good environmental conditions of the known area of occurrence of Boehlkea weitzmani and the absence of signs of imminent impacts, and according to the International Union for Conservation of Nature (IUCN) categories and criteria ( IUCN Standards and Petitions Subcommittee, 2016), we suggest that Boehlkea weitzmani can be classified as a Least Concern (LC) species.