Cyphocharax cramptoni, Bortolo & Lima, 2020

Bortolo, Gustavo Ceolin & Lima, Flávio César Thadeo de, 2020, A new species of Cyphocharax (Characiformes: Curimatidae) with a horizontal color pattern from the rio Tapajós drainage, Amazon basin, Brazil, Neotropical Ichthyology 18 (2), pp. 1-10 : 2-6

Cyphocharax cramptoni , new species

urn:lsid:zoobank.org:act:83830F09-3E3A-4D4D-AC98-4F6CC7E68C8D

( Fig. 1 ; Tab. 1 )

Holotype. ZUEC 17124 , 49.7 mm SL, Brazil, Pará , Santarém , rio Mentaí (trib. rio Arapiuns), village of Cachoeirinha, 2°43’28.64”S 55°36’5.60”W, F. C. T. Lima, B. B. Calegari, W. G. R. Crampton and E. Cerdeira, 26–27 Nov 2015.

Paratypes. MCP 54224 , 2 , 32.2–34.7 mm SL; MPEG 38861, 2 , 26.0– 29.8 mm SL; UF 243981, 2 , 31.2 –41.0 mm SL; ZUEC 12071, 4 , 22.9–30.2 mm SL (24.4 mm SL c&s), same data as holotype .

Diagnosis. Cyphocharax cramptoni is distinguished from most congeners, except C. helleri (Steindachner) , C. multilineatus (Myers) , and C. pantostictos by possessing series of horizontal stripes along the body on the lateral and dorsolateral surfaces of the body (vs. absence of a similar pattern in the remaining Cyphocharax species). It can be distinguished from Cyphocharax helleri and C. multilineatus by possessing horizontal stripes formed by series of conspicuous dark spots situated over the center of the scales on the lateral and dorsolateral surfaces of the body (vs. stripes along the areas of overlap of horizontal rows of scales along the body in C. helleri and C. multilineatu s). It can be additionally distinguished from C. multilineatus by possessing a rounded dark blotch at the caudal peduncle (vs. absence) and longitudinal dark stripes straight (vs. wavy). Cyphocharax cramptoni is distinguished from C. pantostictos by the presence of a rounded dark blotch at the caudal peduncle (vs. presence of a narrow, midlateral, horizontally elongate dark stripe on the caudal peduncle), by possessing a postorbital stripe (vs. absence), by possessing a smaller length of postorbital portion of head (28–37% HL vs. 42–46% of HL, respectively), and a larger orbital diameter (38–45% of HL vs. 24–33% of HL, respectively).

Description. Morphometric data of eleven specimens is presented in Tab. 1 . Body moderately elongate, somewhat compressed laterally. Dorsal profile of head slightly convex from upper lip to vertical line through posterior nostril; straight or slightly convex from that point to tip of supraoccipital spine. Dorsal profile of body straight or smoothly curved from tip of supraoccipital spine to dorsal-fin origin; dorsal-fin base straight to slightly convex in smaller individuals and posteroventrally slanted; straight from base of last dorsal-fin ray to adipose fin; slightly concave from adipose fin to first procurrent ray. Ventral profile of body gently convex from tip of lower jaw to caudal peduncle. Ventral profile of caudal peduncle slightly concave. Prepelvic region somewhat flattened transversely, with median series of scales not enlarged relative to those on adjoining portions of body.

Dorsal fin pointed, with distal margin straight and first and second branched rays longest. Pectoral-fin profile pointed. Tip of adpressed pectoral fin falls four or five scales short of vertical through pelvic-fin origin. Pelvic-fin profile pointed. Tip of adpressed pelvic fin falls one or two scales short of anus. Caudal fin forked, with lobe tips pointed. Adipose fin well developed. Anal fin emarginate with first branched ray longest and about three times length of ultimate ray.

Head profile anteriorly pointed overall from lateral view but rounded in region of mouth and snout. Upper jaw longer than lower jaw, with mouth slightly subterminal. Nostrils very close to each other; anterior circular to ovoid, posterior crescent-shaped with aperture closed by thin flap of skin separating nostrils. Adipose eyelid well developed and extending posteriorly onto anterodorsal portion of opercle. Smaller specimens (22.9–34.7 mm SL) with central aperture in adipose eyelid rounded, approximately corresponding to limits of pupil. Larger specimens (49.7 mm SL) with opening vertically-ovoid, with eyelid overlapping anterior and posterior portions of pupil.

All scales of lateral line pored, with primary laterosensory canal straight. Pored lateralline scales from supracleithrum to hypural joint 28(1), 29*(4) or 30(5). Pored scales on basal portions of caudal fin posterior to hypural joint 2(6) or 3*(2). Scales in transverse series from dorsal-fin origin to lateral line 5*(11). Scales in transverse series from anal-fin origin to lateral line 4*(11). Scales in transverse series from pelvic-fin origin to lateral line 5*(11). Scales between anus and anal-fin origin 1*(8) or 2(2). Middorsal series of scales from rear of supraoccipital spine to dorsal-fin origin 8(1), 9(7) or 10*(3). Anterior scales similar in size to those on posterior portion of caudal peduncle; scale size slightly decreasing in size distally.

Dorsal-fin rays iii,9*(10) or iii,10(1), first unbranched ray very short. Anal-fin rays iii,7*(9), iii,8(2) first ray very short. Pelvic-fin rays i,7,i*(11). Pectoral-fin rays 13*(6), 14(4) or 15(1). Ventral procurrent rays 7(1). Dorsal procurrent rays 7(1). Total vertebrae 31(1).

Coloration in alcohol. Overall body ground coloration tan, darker on dorsal portion of body and head, especially in larger specimens. Dark postorbital stripe hourglass-shaped formed by highly concentrated dark chromatophores situated over opercle. Scales on lateral and dorsal surfaces of body with dark patch of pigmentation at base and center of each scale, fading towards distal portion; spots more developed at midlateral portion of body; larger specimens with blurred portion of spots darker, connecting dots, giving aspect of horizontal stripes passing through scales on lateral portion of body; smaller specimens with spots of each scale isolated, with less intense posterior blur. Spots arranged in nine horizontal series, dorsal and ventral series of dark spots less apparent in smaller specimens. Series of dark spots on scales less developed posteriorly on scale rows ventral of lateral line; very poorly developed in series starting immediately posterodorsal to origin of pectoral fin. Intense dark spots also progressively less pronounced in horizontal series dorsal to lateral line. Small, rounded, conspicuous spot on midlateral surface of caudal peduncle, extending to end of caudal peduncle but not onto caudal fin. All fins hyaline, with few, scattered dark chromatophores.

Coloration in life. Based on a picture of a living specimen taken in field ( Fig. 1B ). Overall coloration glossy grey, with a greenish tint on dorsal and lateral surfaces of body. Top of head and snout dark grey. Abdominal area and lower surface of head whitish to silvery. Discrete, relatively broad longitudinal dark stripe running from snout tip to posterior portion of eye. Postorbital region with a greenish metallic tint; opercle plumbeous. Fins with a light-yellow pigmentation over rays, fading towards tips. Dark pigmentation as in preserved specimens.

Distribution. Cyphocharax cramptoni is only known from the Rio Mentaí, a tributary of rio Arapiuns, lower rio Tapajós basin, Amazon basin, Pará, Brazil ( Fig. 2 ).

Habitat notes. The rio Mentaí, at the type locality of Cyphocharax cramptoni , is a small 10–15 meters wide clearwater river with a bottom composed mainly of sand, submerged rocks, and abundant submerged vegetation at the shoreline and shallower portions. Water parameters at the time of collecting were: water temperature 26.9ºC, conductivity 11.8 µs/cm, pH 4.2, dissolved oxygen 5.5 mg /l, and turbidity 0.72.

Etymology. The new species is named in honor to William G. R. Crampton, in recognition of his important contributions to the knowledge of the fishes from the Amazon basin. A name in the genitive case.

Conservation Status. Cyphocharax cramptoni is only known from few specimens from a single locality in the rio Mentaí , which together with the rio Maró and rio Aruã , form the rio Arapiuns. It seems very likely that the species is more widespread in the basin and perhaps, adjacent portions of the Amazon basin, although more collecting efforts are necessary. The rio Arapiuns basin has been subject to some anthropogenic impacts such as bauxite mining in the rio Aruã basin and selective logging, but these impacts do not seem to have caused major disturbances on the local aquatic environments. The type locality lies within the Reserva Extrativista Tapajós-Arapiuns, which afford some legal protection to the area. Since this is the only information currently available for the species, we recommend the status Least Concern ( LC) following IUCN’s criteria ( IUCN Standards and Petititon Subcommittee, 2019).

Figures

FIGURE 1 | Cyphocharax cramptoni; A. holotype, ZUE C 17124, 49.7 mm SL, Brazil, Pará, Santarém, rio Mentaí; B. Living specimen, ZUEC 12071, 30.2 mm SL, same data as holotype.

FIGURE 2 | Map of the lower Tapajós basin and its confluence with rio Amazonas showing the distribution of Cyphocharax cramptoni. The red dot indicates the type locality.