Leporinus sidlauskasi, Britski & Birindelli, 2019

Britski, Heraldo A. & Birindelli, José L., 2019, Description of a new species of Leporinus (Characiformes: Anostomidae) from the Rio Tapajós basin, Brazil, Zootaxa 4603 (1), pp. 183-191 : 184-188

Leporinus sidlauskasi , new species

( Figs. 1–2 )

Leporinus sp. 4 cf. vanzoi .— Buckup et al., 2011: 244 (checklist, rio Tapajós basin).

Leporinus vanzoi .— Ohara et al., 2017: 97 (field guide, rio Teles Pires basin) (in part, MZUSP 116700 and MZUSP 116677 [not MZUSP 116451], INPA specimens not examined).

Leporinus cf. vanzoi .—Birindelli & Britski, 2013: 1160 (comparative material, MZUSP 96136).

Holotype. MZUSP 123539, 116.8 mm SL, Brazil, Mato Grosso, Itaúba, creek tributary of the rio Teles Pires , at the margin of road, 11°08’42”S 55°35’21”W, J. L. Birindelli & P. Hollanda Carvalho, 30 Sep 2007 .

Paratypes. All from Brazil . MCP 39751, 6 , 77.8–102.8 mm SL, Mato Grosso, Alta Floresta, rio Teles Pires, road MT-320, between Nova Cana „ do Norte and Alta Floresta, 10°14’17”S 55°48’28”W, R. E. Reis, L. R. Malabarba & E. H. Pereira, 22 Jan 2002 . MNRJ 23412 , 1 , 111.0 mm SL, Mato Grosso, Tapurah, rio Teles Pires, near bridge of MT-220, 11°39’13”S 55°42’16”W, P. A. Buckup et al., 20 Jan 2002 . MZUEL 19547 , 2 , 86.8–108.8 mm SL, 2 CS, 88.8–104.0 mm SL, Mato Grosso, Itaúba, rio Teles Pires, 10°58’30”S 55°44’03”W, J. L. Birindelli & P. Hollanda Carvalho, 0 1 Oct 2007 . MZUSP 96136 , 8 , 84.69–109.17 mm SL, same data as MZUEL 19547 . MZUSP 96137 , 4 , 100.6 – 198.5 mm SL, Mato Grosso, Itaúba, rio Renato, tributary of rio Teles Pires, at bridge on road BR- 163, 11°03’24”S 55°16’22”W, J. L. Birindelli & P. Hollanda Carvalho, 25 Sep 2017 . MZUSP 96138 , 5 , 85.2–111.3 mm SL, same data as holotype . MZUSP 96139 , 10 , 85.7–101.7 mm SL, Mato Grosso, Itaúba, rio Teles Pires, 11°03’44”S 55°19’08”W, J. L. Birindelli & P. Hollanda Carvalho, 26 Sep 2007 . MZUSP 96140 , 2 , 88.0– 108.8 mm SL, Mato Grosso, Paranaíta, rio Teles Pires, near ferryboat on MT-416, 09°27’07” S 56°30’46”W, L. M. Sousa & A. L. Netto-Ferreira, 27 Sep 2007 . MZUSP 96141 , 14 , 60.8–76.6 mm SL, Pará, Jacareacanga, rio Teles Pires, downstream Sete Quedas waterfall, 09°19’01”S 56°46’47”W, L. M. Sousa & A. L. Netto-Ferreira, 26 Sep 2007 . MZUSP 96622 , 2 , 100.3 – 114.2 mm SL, Mato Grosso, Peixoto de Azevedo, rio Peixoto de Azevedo, tributary of rio Teles Pires, 10°13’14”S 54º58’02”W, J. L. Birindelli, A. L. Netto-Ferreira, L. M. Sousa, M. H. Sabaj-Pérez & N. Lujan, 16 Oct 2007 . MZUSP 98336 , 1 , 91.9 mm SL, Mato Grosso, Paranaíta, rio Teles Pires, left bank at Canal do Breda, 09°27’34”S 56°28’11”W, M. V. Loeb & A. de Castro, 21 Jan 2008 . MZUSP 98426 , 1 , 88.5 mm SL, Mato Grosso, Paranaíta, rio Teles Pires, at Lago do Socó, 09°25’03”S 56°33’03”W, M. V. Loeb & A. de Castro, 22 Jan 2008 . MZUSP 98922 , 4 , 63.0– 95.3 mm SL, Mato Grosso, Itaúba, river crossing road BR-163, 11°06’10”S 55°17’59”W, P. Hollanda Carvalho & S. Lima, 18 Feb 2008 . MZUSP 99377 , 9 , 81.1–96.2 mm SL, Mato Grosso, Itaúba, rio Teles Pires downstream mouth of rio Renato, 11°03’44”S 55°19’08”W, P. Hollanda Carvalho & S. Lima . MZUSP 99920 , 2 , 36.4–49.3 mm SL, Mato Grosso, Jacareacanga, tributary of left bank of rio Teles Pires, immediately below Sete Quedas, 09°18’27”S 56°47’38”W, L. M. Sousa & A. Netto-Ferreira, 9 Jun 2008 . MZUSP 100045 , 1 , 34.3 mm SL, Mato Grosso, Paranaíta, rio Teles Pires above Sete Quedas rapids, 09°23’53”S 56°34’37”W, L. M. Sousa & A. L. Netto-Ferreira, 16 Jun 2008 .

Non-types. All from Brazil . MCP 30759, 18 , 42-44 mm SL ; MCP 30760, 2 , 65-72 mm SL, Mato Grosso, Tabapor „, rio Teles Pires at MT-220, between Sinop and Porto dos Gaúchos, 11°39’15”S 55°42’18”W, R. E. Reis et al., 20 Jan 2002.

Diagnosis. Leporinus sidlauskasi is distinguished from congeners, except L. amblyrhynchus , L. britskii , L. geminis , L. microphysus , L. parvulus , L. taeniatus , L. taeniofasciatus , L. unitaeniatus , and L. vanzoi , by having a dark midlateral stripe on the body and dark transversal bars on the dorsum. Leporinus sidlauskasi is distinguished from L. microphysus by having gas bladder not reduced in size (vs. reduced in size), and 40 to 42 lateral-line scales (vs. 38 to 40); from L. amblyrhynchus and L. britskii by having 16 circumpeduncular scale series (vs. 12); from L. geminis , L. unitaeniatus and L. vanzoi for having three teeth on the premaxilla (vs. four); from L. parvulus , L. taeniatus and L. taeniofasciatus by having 40 to 42 lateral-line scales (vs. 36 to 38). See the Discussion, for additional comments on the diagnosis of the species.

Description. Morphometric data in Table 1 . Small-sized species when compared with congeners, largest examined specimen 198.5 mm SL. Head and body elongate and moderately compressed ( Figs. 1 and 2 ). Dorsal profile convex from snout tip to vertical through anterior nostril, straight or gently convex from latter point to supraoccipital spine, convex from that point to dorsal-fin origin, straight along dorsal-fin base, approximately straight from dorsalfin terminus to adipose fin, and distinctly concave from adipose fin to anteriormost dorsal caudal-fin procurrent ray. Ventral profile slightly convex from tip of lower jaw to vertical through pectoral-fin origin, distinctly convex from that point to pelvic-fin origin, approximately straight or gently convex from latter point to anal-fin origin, straight along anal-fin base, and distinctly concave from anal-fin terminus to anteriormost ventral caudal-fin procurrent ray. Greatest body depth at origin of dorsal fin. Head somewhat compressed; mouth subterminal, anterior opening of mouth positioned at horizontal bisecting inferior margin of eye or slightly below.

Premaxillary with three* (29) teeth decreasing in size posteriorly from symphyseal tooth ( Fig. 3 ). Dentary with four* (29) teeth also decreasing in size posteriorly symphysial tooth. Teeth incisiform, arranged in a stair-step pattern on both jaws.

Scales cycloid. Lateral line with 40* (13), 41 (10) or 42 (3) perforated scales extending from posterior margin of opercle to base of median caudal-fin rays. Horizontal scale rows between dorsal-fin origin and lateral line 6* (29). Horizontal scale rows between lateral line and pelvic-fin origin 5* (29). Horizontal scale rows around caudal peduncle (circumpeduncular scale series) 16* (29). Predorsal scales from tip of supraoccipital to dorsal-fin origin 12 (7), 13* (12) or 14(3). Dorsal scales from dorsal-fin posterior insertion (terminus) to adipose-fin origin 12 (2), 13* (12) 14 (10) or 15 (2). Dorsal scales between adipose-fin terminus and first dorsal procurrent caudal-fin rays 7* (8), 8 (19) or 9 (1). Prepelvic scales 17 (3), 18* (5), 19 (8) or 20 (5). Scales from pelvic-fin base to anus 8 (1), 9* (17) or 10 (9). Scales between anus and anal-fin origin 2 (4), 3* (11) or 4 (4). Scales from anal-fin terminus to first procurrent caudal-fin ray 6* (8), 7 (13), 8 (5) or 9 (1). Base of anal-fin rays covered by a single row of five to seven small elongate scales.

Dorsal-fin rays ii,9,ii*(28). Dorsal-fin origin at vertical through second or third scales in front of pelvic-fin origin. Dorsal-fin distal margin gently convex. Adipose fin small, its base at vertical through last anal-fin rays. Pectoral-fin rays i,14 (6), i,15 (14) or i,16* (9). Tip of pectoral-fin rays extending to fifth or sixth scale in front of pelvic-fin origin. Pelvic-fin anterior base at vertical through base of first to third branched dorsal-fin ray. Pelvic-fin rays i,8* (29). Tip of pelvic fin reaching fourth to sixth scale in front of anus. Anal-fin rays ii,7,ii* (28) or ii,8,ii (1). Anal-fin origin at vertical through fourth to fifth scale in front of adipose fin. Distal margin of anal fin convex, extending to last scales of ventral row or reaching procurrent caudal-fin rays. Anteriormost branched anal-fin ray about three times longer than posteriormost ray. Last anal-fin ray usually split to its base. Principal caudal-fin rays i,8,9,i* (29). Caudal fin forked, with lobes approximately similar in size or upper lobe slightly longer than lower lobe. Vertebrae 37 (2), with vertebrae 5 to 24 bearing ribs, 4 (2) branchiostegal rays.

Color in alcohol. Ground color light beige to light brown ( Fig. 1 ). Head and body slightly countershaded, gradually darker above midlateral line from mouth to caudal fin. Body with a dark midlateral stripe from opercle to base of caudal fin; midlateral stripe continuous at caudal peduncle in some specimens and interrupted at the caudal peduncle in others ( Fig. 2 ). Fourteen to 15 dark transverse bars on body dorsum, ventrally extended on two or three scale series below middorsal series, five or six dark bars between tip of supraoccipital and dorsal-fin origin, two on dorsal-fin base, five between dorsal-fin terminus and adipose-fin origin, two between adipose-fin terminus and caudal fin. In large individuals (above 100 mm SL), ventral portion of dark transverse bars typically darker, standing out as separate blotches. Midlateral dark stripe extending anteriorly throughout head and snout, inconspicuous in some specimens. Upper lip dark. Small specimens (up to 40 mm SL) with a distinct dark spot on median portion of caudal-fin base, gradually fading and disappearing completely in larger specimens. Fins hyaline, with tiny, scattered chromatophores. Dorsal, adipose and caudal fins slightly darker than pectoral, pelvic and anal fins.

Color in life. Similar to described above for alcohol-preserved specimens, except for overall coloration of body more silvery, and fins yellowish, especially the pectoral, pelvic and anal fins, the latter two with anteriormost rays whitish in some specimens, and adipose fin yellow at its proximal half and red in the distal half. Eye with a red spot at the postero-dorsal portion of the iris ( Fig. 2 ).

Etymology. The specific name honors Brian L. Sidlauskas, for the important contributions to our knowledge of the systematics of Anostomidae .

Geographic distribution. Leporinus sidlauskasi is known from the middle and upper portions of the rio Teles Pires basin and tributaries ( Fig. 4 ). Because all specimens were collected in rio Teles Pires upstream from or immediately below the rapids of Sete Quedas, the new species seems to be endemic from that area. The rio Teles Pires joins the rio Juruena forming the the rio Tapajós river, at the border of Mato Grosso and Pará states, Brazil ( Fig. 5 ).

Conservation status. Leporinus sidlauskasi is widely distributed in the most of the Rio Teles Pires, where it occurs preferably in large rivers. Despite existing habitat degradation due especially to expansion of farming, the species seems to be relatively abundant where it occurs. Therefore, L. sidlauskasi would be classified as Least Concern (LC) according to the International Union for Conservation of Nature (IUCN) categories and criteria.

Figures

FIGURE 1. Leporinus sidlauskasi, holotype MZUSP 123539, 116.8 mm SL: Brazil, Mato Grosso, Itaúba, Rio Teles Pires basin.

FIGURE 2. Live specimens of Leporinus sidlauskasi, showing slightly distinct color pattern on caudal peduncle, (A) MZUSP 96137, c.160 mm SL, paratype; (B) MZUSP 96138, c.100 mm SL, paratype.

FIGURE 3. Jaws and teeth of Leporinus sidlauskasi, MZUEL 19547, 108.8 mm SL, paratype, and L. vanzoi, MZUSP 98327, 96.5 mm SL.

FIGURE 4. Type locality of Leporinus sidlauskasi, rio Teles Pires at Itaúba, Mato Grosso, Brazil, and the creek where the holotype was collected (inset).

FIGURE 5. Map showing the distribution of Leporinus sidlauskasi. Red cross indicates the Sete Quedas rapids, and star indicates type locality.

Tables

TABLE 1. Morphometric data for Leporinus sidlauskasi. SD for Standard Deviation.

	N	Mean	Range	SD	Holotype
					(MZUSP 123539)
Standard length (mm)	29		77.80–130.97		116.69
Percentages of standard length
Body depth	29	23.6	20.6–28.2	1.936	22.4
Caudal peduncle depth Predorsal distance	29 29	8.7 48.1	7.8–9.4 42.1–50.5	0.351 1.535	8.4 49.8
Prepelvic distance	29	52.1	50.1–56.2	1.433	51.6
Pectoral length	29	16.2	12.4–25.7	2.609	17.9
Pelvic length	29	52.1	50.1–56.2	1.433	51.6
Head length	29	25.0	20.1–27.0	1.234	24.0
Percentages of head length
Eye diameter	29	26.5	24.4–31.1	1.644	27.1
Snout length	29	43.9	40.5–53.9	3.098	42.8
Bony interorbital	29	41.5	37.2–54.1	3.493	44.6