Leptotocinclus madeirae, Delapieve & A. & Reis, 2017

Delapieve, Maria Laura S., A., Pablo Lehmann & Reis, Roberto E., 2017, An appraisal of the phylogenetic relationships of Hypoptopomatini cascudinhos with description of two new genera and three new species (Siluriformes: Loricariidae), Neotropical Ichthyology 15 (4), No. e 170079, pp. 1-38 : 28-30

Leptotocinclus madeirae , new species

u r n:l s i d:z o o b a n k.o rg:a c t: 3 7 9 B5 5F 7-D F 5 3-4 3D 5-9E B9- 5651BE6E36AF

Fig. 18

Holotype. MCP 51352, female, 30.4 mm SL, Brazil, Amazonas , Humaitá , igarapé do Vinte e Dois at Recanto do Sanari , Transamazon road ca. 20 km SW of rio Madeira towards Lábrea, 07°35’36”S 63°10’27”W, 27 July 2004, P. Lehmann, P. Buckup, F. Lima, V. Bertaco & J. Pezzi.

Paratypes. Brazil: Amazonas State, Rio Madeira basin: MCP 35888, 3 , 20.5 - 23.4 + 2 c&s, 23.7-23.8 mm SL, same data as holotype. MCP 35886, 4 , 18.4 - 23.9 + 1 c&s, 24.8 mm SL, igarapé do Doze at Transamazon road, ca. 12 km W of Humaitá towards Lábrea , 07°34’25”S 63°06’39”W, 27 July 2004, P. Lehmann, P. Buckup, F. Lima, V . Bertaco & J. Pezzi. UFRO-I 15682 , 5 , 19.7-24.8 mm SL, creek on Transamazon road, ca. 18 km W of Humaitá, 07°35’36.7”S 63°10’31”W, 9 August, 2012, D. Hungria . Rio Purus basin: MCP 35885, 1 ,

20.4 mm SL, creek tributary to rio Açuá , ca. 136 km SW of Humaitá on road BR-319, Humaitá , 08°12’13”S 63°53’01”W, 28 July 2004, R. Reis, F. Langeani, E. Pereira & A. Cardoso. UFRO-I 16658 , 11 , 16.2-30.6 mm SL, rio Fortaleza on road BR-319, near Realidade village , ca. 90 km N of Humaitá, 07°05’04.5”S 63°06’35”W, 9 August 2012, W. M. Ohara. UFRO-I 15681 , 11 , 19.0- 25.6 mm SL + 1 c&s, 22.9 mm SL, rio Realidade on road BR-319, at Realidade village , ca. 100 km N of Humaitá, 06°59’07”S 63°05’54.4”W, 9 August 2012, W. M. Ohara. UFRO-I 17317 , 2 , 20.2-23.1 mm SL, rio Realidade on road BR-319, at Realidade village, ca. 100 km N of Humaitá, 06°59’07”S 63°05’53.4”W, 9 August 2012, W. M. Ohara. UFRO-I 15704 , 4 , 21.6-25.7 mm SL, mouth of lago Comprido into rio Ipixuna, near Transamazon road, ca. 38 km W of Humaitá, 07°30’37”S 63°20’23.6”W, 21 July 2012, W. M. Ohara .

Diagnosis. Leptotocinclus madeirae is distiguished from L. ctenistus by lacking a median series of abdominal plates (vs. median series of plates present and arranged in one single row); and by 1-2 (except one specimen with 3) lateral abdominal plates (vs. 3-6). Additionally, Leptotocinclus madeirae is distinguished by the smaller size of the preanal plate (1.5-6.4% SL, Fig. 7e vs. 7.0-12.0% SL, Fig. 7f).

Description. Proportional measurements and counts in Tabs. 2-3. Body relatively small and slender, moderately elongated; head moderatly depressed. Dorsal profile of head and body slightly convex from snout tip to dorsal-fin origin; parietosupraoccipital slightly elevated leaving interorbital region convex. Trunk profile descending from dorsal-fin origin to anteriormost procurrent caudal-fin ray. Body deepest at dorsal-fin origin; body shallowest at posterior portion of caudal peduncle. Body ovoid to transversely depressed in cross section, progressively compressed posterior to anal-fin base. Greatest body width at cleithrum.

Anterior margin of snout broadly rounded in dorsal view. Snout with slight depression anterior to each nostril. Eye large, laterally positioned, barely visible in ventral view; iris operculum absent. Compound pterotic perforate only laterally, fenestrae increasing in size towards posterolateral margin of bone. Pore between canal-bearing cheek plate and fourth infraorbital present. Three predorsal plates anterior to trapezoidal nuchal plate. Odontodes on dorsal margin of snout slightly larger than other odontodes on head. Odontodes on ventral margin of snout distinctly enlarged. Posterior tip of parieto-supraoccipital with small tuft of enlarged odontodes in specimens smaller than 20 mm SL; without other crests on dorsal surface of head. Lips rounded and covered with globular papillae. Teeth slender, bifid, with blade-like larger medial cusp and smaller lateral cusp. Plates anterior to cleithrum absent.

Median series of lateral plates complete with continuous lateral line. Odontodes on head and trunk pointed, uniform in size and shape and conspicuously aligned; odontodes on caudal peduncle slightly larger. Odontodes on ventral surface of body smaller and scattered, not arranged in lines. Body covered by plates, except area around anus, region overlying lateral opening of swimbladder capsule, area between lower lip and pectoral girdle, and area around fin bases. Ventral portions of cleithrum and coracoid completely exposed and supporting odontodes. Abdomen covered by 1-3 (mean 2) small, ovate lateral abdominal plates; middle abdominal plates absent. Single, small preanal plate between pelvic fins. Anal tube slightly right turned. Total vertebrae 26; ribs 7, beginning on eighth vertebral centrum, in addition to large rib on sixth centrum.

Dorsal fin I,7, its origin at vertical through middle of pelvic fin. Dorsal-fin spinelet absent. Pectoral fin I,6, with small axillary slit in skin behind fin insertion. Serrae absent along mesial margin of pectoral-fin spine. Pectoral fin reaching to vertical through midpoint of pelvic-fin unbranched ray. Adipose fin absent. Pelvic fin i,5, short, with robust thickened first ray shorter than two first branched rays. Odontodes on pelvic-fin unbranched ray turned and strongly pointing mesially. Anal fin i,5; first anal-fin pterygiophore exposed in front of unbranched fin ray. Caudal fin i,12,i, forked, upper and lower lobes equal.

Color in alcohol. Ground color of dorsal surface of head and body tan to medium brown. Dark brown melanophores on head more densely concentrated on compound pterotic, parieto-supraoccipital, frontals, postrostral plates, anterior surface of upper lip, and posterior and mesial portions of naris flap. Melanophores on body concentrated on predorsal area and lateral stripe. Longitudinal dark brown lateral stripe on midlateral surface of head and body; lateral stripe from snout tip partially covering ventral half of eye and continuing to end of caudal peduncle. Light brown melanophores arranged in four inconspicuous dorsal blotches; one anterior to dorsal fin, one on posterior portion of dorsal fin, two at caudal peduncle. Posteriormost plates of both dorsal and ventral series of lateral plates less pigmented. Ventral surface of body mostly unpigmented except for ventral portion of snout plates, canal-bearing cheek plate, lateral region of pectoral girdle, and lateral portions of caudal peduncle. Dorsal and pectoral fins with 5-6 dark brown spots, continued as irregular bands on branched rays. Pelvic fin with 3-4 and anal fin with two spots. Caudal fin with trapezoidal dark brown spot at base and 3-4 bands of brown melanophores on unbranched and branched rays. Interradial membrane of all fins unpigmented.

Sexual dimorphism. A single known male (UFRO-I 16658) with a small urogenital papilla behind the anal tube.

Distribution and habitat. Leptotocinclus madeirae is known from tributaries to the middle rio Madeira and Purus in Brazil ( Fig. 16). Collecting localities are blackwater creeks and small rivers.

Etymology. Leptotocinclus madeirae is named after the rio Madeira, in which basin is the type-locality. An adjective.

Conservation status. Leptotocinclus madeirae is relatively frequent and abundant in the tributaries of the middle rio Madeira, with an EOO of approximately 2,700 km 2. As the population is not fragmented, continuing decline cannot be inferred, and no eminent threats are detected, L. madeirae can be categorized as Least Concern (LC) according to the International Union for Conservation of Nature (IUCN) categories and criteria ( IUCN Standards and Petitions Subcommittee, 2016).