Eurycheilichthys vacariensis, Reis, 2017

Reis, Roberto E., 2017, Unexpectedly high diversity in a small basin: A taxonomic revision of Eurycheilichthys (Siluriformes: Loricariidae), with descriptions of seven new species, Neotropical Ichthyology 15 (1), No. e 160068, pp. 1-28 : 24-26

Eurycheilichthys vacariensis , new species

urn:lsid:zoobank.org:act:DBB7C806-28CE-4D85-819E-622288DD3ADD

Fig. 15; Tabs. 2-4

Eurycheilichthys sp. 6 .- Reis, Carvalho, 2007: 84 [listed].

Holotype. MCP 40659, 47.6 mm SL, male, Brazil, Rio Grande do Sul, Muitos Capões, arroio Espeto, also known as rio Soares , rio Taquari basin, on road from Muitos Capões to Vacaria (28º23’26”S 51º03’22”W), 3 Apr 1999, V. A. Bertaco et al.

Paratypes. Brazil: Rio Grande do Sul: upper rio Taquari drainage: MCP 22782, 16 , 26.1-47.5 mm SL, 2 c&s, 42.1- 45.0 mm SL (10, 36.2-44.8 mm SL), MZUSP 92421 , 3 (3, 35.4-40.0 mm SL), and AMNH 238570 , 3 (3, 37.6-46.1 mm SL), collected with the holotype. MCP 22790, 6 , 23.4- 46.4 mm SL (1, 46.4 mm SL), arroio Carazinho , on road between Lagoa Vermelha and Vacaria, Lagoa Vermelha (28º17’36”S 51º24’42”W), 3 Apr 1999, V. A. Bertaco et al. MCP 22801, 8 , 30.8-40.6 mm SL (5, 32.9-40.6 mm SL), arroio Tavoqua, near Fazenda Cambará, Muitos Capões (28º21’51”S 51º17’53”W), 3 Apr 1999, V. A. Bertaco et al. MCP 35037, 7 , 41.9 -48- 7 mm SL, 13 tis, 28.9-46.9 mm SL, arroio Atanásio, on road from Nova Bassano to Nova Prata, Nova Bassano (28º44’25”S 51º41’15”W), 22 May 2004, R. E. Reis et al .

Genseq- 2 16S. MCP 35037; GenBank accession number KX355636 .

Genseq-2 COI. Sequences deposited in GenBank by Cristian Cramer for COI ( MCP 22790; GenBank accession number EU370993 ) .

Non-types. Brazil: Rio Grande do Sul: upper rio Taquari drainage: MCP 35125, 10 , 35.0- 46.1 mm SL, 15 tis, 23.0- 43.4 mm SL, rio Turvo near Turvo , on road from André da Rocha to Barretos , Turvo (28º24’19”S 51º29’25”W), 22 May 2004, R. E. Reis et al. MCP 35123, 10 tis, 22.4-44.7 mm SL, arroio Espeto or rio Soares , on road from Muitos Capões to Vacaria, Muitos Capões (28º23’26”S 51º03’22”W), 23 May 2004, R. E. Reis et al. MCP 22257, 11 , 44.5-52.6 mm SL, arroio Atanásio, on road from Nova Bassano to Nova Prata, Nova Bassano (28º44’25”S 51º41’15”W), 20 Jan 1999, R. E. Reis et al .

Neotropical Ichthyology, 15(1): e160068, 2017 Roberto E. Reis

Diagnosis. Eurycheilichthys vacariensis is distinguished from E. limulus , E. castaneus , E. paucidens , and E. apocremnus by possessing 24-26 plates in middle lateral series (vs. 27-30 plates – occasionally 26 in E. paucidens , and E. apocremnus ). It is further distinguished from E. limulus and E. castaneus by possessing a body and head with dark blotches and spots (vs. body and head plain dark brown, without blotches or spot, and with thin light stripes from snout tip, crossing above the eye and predorsal area); from E. paucidens by a shorter pelvic-fin spine (14.6-20.1 vs. 19.4-24.2% SL), larger orbital diameter (12.5-16.9 vs. 9.3-12.4% HL), and numerous (35-45) accessory teeth on premaxilla in several irregular series (vs. fewer, 2-10 accessory teeth on premaxilla, in one irregular series); and from E. apocremnus by a shorter pelvicfin spine (14.6-20.1 vs. 20.4-23.3% SL). Eurycheilichthys vacariensis is distinguished from E. coryphaenus by having the parieto-supraoccipital without a conspicuous elevation (vs. parieto-supraoccipital conspicuously elevated - Fig. 3); from E. pantherinus and E. planus by having the abdomen incompletely covered with granular platelets (vs. abdomen naked in E. planus and fully plated in E. pantherinus ); and from E. luisae by the large, irregular, dark spots on body, with head mostly dark (vs. body and head covered with many small, roundish, dark spots), and by the lower lip hardly reaching the anterior margin of the pectoral girdle (vs. lower lip extending past the pectoral girdle).

Description. Proportional measurements and counts in Tabs. 2, 3, and 4. Dorsal body profile gently arched from snout tip to parieto-supraoccipital bone, straight to slightly arched from that point to dorsal-fin origin. Trunk generally straight and tapering slightly to caudal-fin base. Trunk and caudal peduncle rounded in cross section, slightly flattened at and behind base of dorsal and anal fins and compressed caudally. Greatest body depth at dorsal-fin origin. Head and snout broad and rounded anteriorly, with body progressively narrowing from cleithrum to caudal peduncle. Interorbital space flat to slightly convex; superior margin of orbits slightly elevated. Snout slightly convex anterior to nares. Nostrils located at posterior terminus of pair of elongate, shallow depressions beginning close to snout tip. Eye comparatively small to medium, orbit diameter 12.5-16.9% HL, dorsolaterally placed.

Pectoral fin of moderate size, spine moderately arched, posterior fin-margin rounded; reaching from half to twothirds length of pelvic fin when depressed. Fleshy flap along posterodorsal margin of pectoral-fin spine low in both male and female adults. Pectoral-fin axillary slit present, with large opening ventral to tip of posterior process of cleithrum. Pelvic fin of females short, reaching to point midway between anus and anal-fin origin when depressed. Thickened first pelvic-fin ray of males slightly longer, falling short of anal-fin origin. Males with well-developed

fleshy flap along posterodorsal margin of thickened first

pelvic-fin ray. Dorsal-fin origin slightly posterior to vertical line through posterior of pelvic-fin base; spinelet present, reduced and plate-like; dorsal-fin locking mechanism nonfunctional. Adipose fin absent.

Body entirely covered by dermal plates except for area around anus, opening of swimbladder capsule posteroventrally to compound pterotic, around pectoral- and pelvic-fin insertions, and ventral surface of head around lips. Body and head lacking crests. Coracoid and cleithrum exposed laterally, covered medially by skin or few isolated platelets. Arrector fossa open. Lateral abdominal plates absent. Middle abdominal plates few and granular, typically arranged longitudinally on middle of abdomen, though sometimes covering most of abdominal surface between pectoral girdle and anal opening ( Fig. 2i). Posterior tip of parieto-supraoccipital with small patch of enlarged odontodes compared to those on remainder of head and predorsal area - especially in smaller individuals. Head and body plates covered with odontodes, these larger on ventral face of pelvic and pectoral spines. Odontodes on head and trunk otherwise of uniform size and distribution, not arranged in conspicuous rows.

Lips roundish and wide, papillose, and extending posteriorly to end of canal-bearing lateral cheek plate or between that point and anterior margin of pectoral girdle. Lower lip margin smooth to slightly fringed. Maxillary barbel short, mostly adnate to lower lip. Teeth slender, bifid; major (medial) cusp large, bladelike, and slightly rounded; minor (lateral) cusp minute, pointed. Accessory patch of unicuspid teeth on premaxilla and dentary attached to dermal bone posterior (premaxilla) and anterior (dentary) margin of tooth cup, which encloses main series of emergent and pre-emergent bifid teeth. Accessory teeth elongate, sharply pointed, directed posteroventrally (premaxilla) and anteroventrally (dentary).

Color in alcohol. Background color of dorsal surface of head and body grayish brown; yellowish tan, mostly unpigmented ventrally. Dorsal surface with many dark grayish brown, roundish dots scattered all over head and occasionally predorsal area; dots coalesce into larger blotches on trunk and caudal peduncle. Dorsum with four inconspicuous dark saddles: first on dorsal-fin origin, second posterior to dorsalfin base, and two on caudal peduncle. First thickened ray of dorsal, pectoral, pelvic, and anal fins and external rays of caudal fin with chromatophores arranged in three to five discernible blotches. Branched rays in these fins with similar color pattern, forming bands. Caudal fin hyaline to yellowish tan, with three or four dark irregular vertical bands.

Distribution and habitat. Eurycheilichthys vacariensis is known from localities in the upper reaches of rio Turvo, a tributary to the rio das Antas, rio Taquari basin, Rio Grande do Sul, Brazil ( Fig. 7) - an area located at the extreme northern headwaters of the rio Taquari basin. One

population from the rio Atanásio in the rio Guaporé basin

differs slightly in color pattern from those in the rio Turvo basin and this population is excluded from the type series. The localities are small creeks with medium flowing water and substrate covered with rocks and stones.

Etymology. Eurycheilichthys vacariensis is named after the town of Vacaria, a historical place in the highlands of Rio Grande do Sul that exemplifies the traditional Gaucho culture of the region in which this species occurs.

Conservation status. Eurycheilichthys vacariensis is relatively frequent and moderately abundant in the upper rio Turvo basin. Despite the small Extent of Occurrence (EOO) of approximately 2,700 km 2, no specific threats were detected, and the species can be categorized as Least Concern (LC) according to IUCN criteria (IUCN, 2016).