Hyphessobrycon procyon, Pastana, Murilo N. L. & Ohara, Willian M., 2016

Pastana, Murilo N. L. & Ohara, Willian M., 2016, A new species of Hyphessobrycon Durbin (Characiformes: Characidae) from rio Aripuanã, rio Madeira basin, Brazil, Zootaxa 4161 (3), pp. 386-398 : 387-392

Hyphessobrycon procyon , new species

( Figs. 1 , 3 )

Holotype. MZUSP 118846, 32.2 mm SL, Brazil, Amazonas, Apuí, rio Juma on road BR 230 between Vila dos 180 and Apuí , rio Aripuanã drainage, 7º12’43”S 59º55’18”W, W. M. Ohara & V. Abrahão, 22 Jun 2015.

Paratypes. All from Brazil, Amazonas, Apuí. MZUSP 117601, 10 , 24.6–32.2 mm SL, same data as holotype . MZUSP 117720, 6 , 19.3–30.7 mm SL, tributary of rio Juma, rio Aripuanã drainage, 7º04’10”S 59º57’33”W, W. M. Ohara & V. Abrahão, 24 Jun 2015 . MZUSP 117642, 106 (2 c&s, 22.5–23.7 mm SL), 12.5–30.4 mm SL (7 measured, 20.8–30.4 mm SL). INPA 52184, 20 , 14.3–27.2 mm SL, ZUEC 12825, 10 , 16.8–28.4 mm SL; upstream cachoeira do Paredão, rio Juma, rio Aripuanã drainage, 7º02’58”S 60º03’04”W, W. M. Ohara & V. Abrahão, 24 Jun 2015 .

Non-type material. MZUSP 117691, 16, 12.9–21.4 mm SL, same data as holotype.

Diagnosis. Hyphessobrycon procyon can be distinguished from all congeners, except of H. diastatos Dagosta, Marinho & Camelier , Hyphessobrycon elachys Weitzman , H. heliacus Moreira, Landim & Costa , H. loweae Costa & Géry , H. notidanos Carvalho & Bertaco , H. peugeoti Ingenito, Lima & Buckup , and the Hyphessobrycon species belonging to the rosy-tetra group (sensu Weitzman & Palmer, 1997), by dorsal-fin elongated in mature males (vs. dorsal-fin not elongated). Hyphessobrycon procyon differs from Hyphessobrycon species of the rosy-tetra group by the absence of a dark blotch on dorsal-fin (vs. presence). The new species differs from the remaining Hyphessobrycon species by having two humeral blotches (vs. one humeral blotch in H. heliacus , H. notidanos , H. peugeoti , and H. loweae ; humeral blotch inconspicuous or absent in H. elachys and H. diastatus ). Additionally, Hyphessobrycon procyon can be distinguished from H. diastatos , H. elachys , H. notidanos and H. loweae by having a higher number of branched anal-fin rays (23–26 vs. 15–18 in H. diastatos ; 16–20 in H. elachys ; 17–20 in H. notidanos ; 17–21 in H. loweae ); from H. heliacus by having the pelvic fin not filamentous in adult males (vs. pelvic-fin filamentous), and by chevron-like dark markings along the midline of the body absent or inconspicuous (vs. present and conspicuous); and from H. peugeoti by exhibiting a silvery to yellowish color in live mature males (vs. mature males red in life), and higher number of branched anal-fin rays (23–26, modally, 25 vs. 21–24, modally, 22).

Description. Morphometric data of holotype and paratypes presented in Table 1 . Body compressed, moderately deep, greatest body depth slightly anterior to dorsal-fin origin. Dorsal profile of head convex from upper lip to vertical through posterior nostril; nearly straight from nostrils to tip of supraoccipital spine. Dorsal profile of the body slightly convex from supraoccipital spine to dorsal-fin origin, straight to slightly convex along dorsal-fin base, nearly straight from base of last dorsal-fin ray to adipose fin, and concave along caudal peduncle. Ventral profile of head convex along the dentary, nearly straight along ventral portion of the head, convex from gular area to anal-fin origin, straight to slightly convex along anal-fin base, and concave along caudal peduncle.

Mouth terminal. Posterior terminus of maxilla reaching vertical line through anterior margin of orbit. Premaxillary teeth in two rows. Outer tooth row with 1(1), 2*(13), 3(14), or 4(1) tetra- to pentacuspid teeth. Inner row with 4(2) or 5*(27) penta- to eneacuspid teeth, symphyseal tooth of inner series narrow, asymmetric, with four cusps. Tooth cusps of inner premaxillary row arranged in semicircular line, directed outward. Maxilla with 0(1), 1(1), 2*(26), or 3(1) hexa- to heptacuspid teeth. Dentary with 4*(22) or 5(6) large hexa- to octacuspid teeth followed by one to four smaller uni- to tricuspid teeth ( Fig. 2 ). Cusps of large dentary teeth arranged in semicircular line, directed inward. Central cusp of all teeth slightly more developed than lateral cusps ( Fig. 2 ).

Scales cycloid, with three to thirteen radii; circuli marked anteriorly, absent distally. Lateral line slightly slanted downward and incompletely pored, with 7(4), 8*(11), 9(7), or 10(3) perforated scales. Longitudinal series of scales including perforated scales 30(1), 31(5), 32*(10), or 33(1). Longitudinal scale rows between dorsal-fin origin and lateral line 5*(24) or 6(1). Longitudinal scale rows between lateral line and pelvic-fin origin 4*(25) or 5 (1). Scales around caudal peduncle 11(1), 12*(14), or 13(1). Single row of 4*(2), 5(4), 6(10), 7(3), 8(3), or 9(1) scales covering base of anteriormost anal-fin rays. Caudal fin with scales only basally.

Dorsal-fin rays ii,9*(29). Dorsal-fin origin at mid-body of standard length, slightly posterior to vertical through pelvic-fin origin. First unbranched dorsal-fin ray half of the length of second, or less. Dorsal fin elongated in mature males specimens (3), reaching area between adipose and caudal fin origin when depressed; first to third branched dorsal-fin rays longest. Dorsal fin not reaching adipose-fin origin in females, distal profile of dorsal fin rounded. Base of last dorsal-fin ray at vertical through anal-fin origin. First dorsal-fin pterygiophore inserted behind neural spine of 9th (2) vertebra. Adipose fin present. Anal-fin rays iv 23 (2), 24(10), 25*(15), or 26(2). First anal-fin pterygiophore inserted behind haemal spine of fifteenth (2) vertebrae. Anal-fin margin slightly concave to convex in mature males (3), with almost all rays thick, slightly curved posteriorly; first to fourth branched rays slightly longer than remaining rays, decreasing in length gradually, not forming a conspicuous lobe. Distal margin of anal fin in females with first to seventh branched rays more elongate, forming a conspicuous lobe, remaining rays gradually decreasing in length posteriorly. Pectoral-fin rays i,10*(5), 11(22), or 12(2); tip of fin surpassing pelvic-fin origin. Pelvic-fin rays i,7(29); tip of fin reaching first to fifth anal-fin rays, males with pelvic-fin rays longer than females (see Sexual dimorphism). Caudal-fin rays i,9/8,i*(28) or i,8/8,i(1). Caudal fin forked; upper and lower lobes similar in size. Ten (2) dorsal procurrent caudal-fin rays, and 7(1) or 8(1) ventral procurrent caudal-fin rays.

First gill arch with 17(1) or 18(1) gill rakers: 5(1) or 6(1) rakers on epibranchial, 1(2) between epibranchial and ceratobranchial, 8(2) on ceratobranchial, 1(2) between ceratobranchial and hypobranchial, and 2(2) on hypobranchial. Four (2) branchiostegal rays: three branchiostegal rays articulating with anterior ceratohyal and one with posterior ceratohyal. Vertebrae 32(2). Precaudal and caudal vertebrae 15(2), and 17(2) respectively. Supraneurals 4(2).

Color in alcohol. Overall background coloration of head and body cream. Dorsal portion of head and body dark. High concentration of chromatophores along dorsal midline of body, from tip of supraoccipital spine to anteriormost dorsal procurrent ray. Dark chromatophores concentrated at snout and jaws. Ventral portion of head and body with few scattered chromatophores. Infraorbital series with dark pigmentation present on antorbital and first infraorbital, remaining infraorbitals retaining guanine and lacking black pigmentation. High concentration of guanine on opercular area. Gular area clear. Two humeral blotches present, separated by a light area. First humeral blotch vertically elongated and with margins diffuse, encompassing approximately three scales horizontally and six vertically. Second humeral blotch smaller and fainter, two scales wide and four scales high, fading posteriorly. Thin longitudinal line formed by dark pigmentation running along horizontal septum of body. Line starting on vertical through first to third branched dorsal-fin ray and extending to caudal peduncle. Abdominal region with few scattered chromatophores, more concentrated on posterior portion of body, above anal fin along margins of myosepta.

Dorsal fin coloration sexually dimorphic. Sexually mature males with dark pigmentation concentrated along the entire length of first four dorsal-fin rays. Remaining rays with scattered chromatophores along its anterior and posterior margins and interradial membranes. Females and immature males with dark pigmentation scattered along first two unbranched dorsal-fin rays and interradial membranes. Anal fin with chromatophores spread along margin of rays and interradial membranes, chromatophores more concentrated on distal portion of fin. Pectoral and pelvic fins with scattered chromatophores, pigmentation more concentrated along lateral margin of anteriormost rays. Adipose fin mostly hyaline with scattered chromatophores present only on its origin. Caudal fin mostly hyaline, except on middle caudal-fin rays, presenting chromatophores along rays and interradial membranes. Remaining caudal-fin rays with pigmentation mostly on anterior and posterior margins. Adult males with broad caudal peduncle blotch, expanded dorsally and ventrally, occupying entire caudal peduncle surface. Females and immature specimens usually with a smaller, relatively rounded caudal peduncle blotch. Some adult females may exhibit a caudal peduncle blotch as broad as that present in adult males.

Color in life. Based on photographs of freshly collected specimens ( Fig. 3 ). Top of head and dorsal portion of body tan to brown. Lateral and ventral portion of the head and abdominal region mostly silvery, with scattered dark chromatophores. Dorsal fin yellow on females or immature specimens. Mature males with dark pigmentation along first four dorsal-fin rays and interradial membranes, remaining fin yellow. Pectoral, pelvic and anal fins yellow to orange, with pigmentation more intense along the leading rays of the fins. Adipose fin yellow. Caudal fin mostly yellow, except middle caudal-fin rays and interradial membranes, which are scattered with dark chromatophores. Sexually dimorphic males with concentration of red pigmentation on base of upper and lower caudal-fin rays.

Sexual dimorphism. Adult males of Hyphessobrycon procyon can exhibit a dark coloration on the leading edge of the dorsal fin, resultant of concentration of chromatophores on the two unbranched and first two branched dorsal-fin rays, and interradial membranes. Females and juvenile specimens exhibit a much less pigmented dorsal fin, with chromatophores evenly distributed along fin area. Mature males present a longer dorsal fin, resulting from a pronounced elongation of the first to third branched dorsal-fin ray. The dorsal fin of sexually mature males, when depressed, reaches the portion between the adipose fin and caudal-fin base (n=5). Additionally, mature males present a longer pelvic fin, with its tip reaching the second to fourth branched anal-fin ray when depressed. Females and immature specimens exhibit a pelvic fin slightly shorter in length, reaching the last unbranched to first two branched anal-fin rays when depressed. Mature males with anal-fin margin not forming a discernible lobe along the fin margin. Females and immature specimens exhibit a dorsal fin not elongated, not reaching the adipose fin when depressed, and an anal fin exhibiting a discernible lobe on its anterior portion along the last unbranched and first four branched anal-fin rays. Anteriormost branched anal-fin rays of mature males with fin-ray segments thickened and rounded.

Distribution. The new species is known only from rio Juma and one of its tributaries, rio Aripuanã drainage, rio Madeira basin, Apuí town, Amazonas State, Brazil ( Fig. 4 ).

Etymology. The specific epithet procyon is an allusion to the alpha star of the Canis Minor constellation that represents the state of Amazonas in the Brazilian national flag, a reference of the state of occurrence of the new taxon. A noun in opposition.

Ecological notes. The type-locality of Hyphessobrycon procyon is a clear water river 40 m wide, 0.5-2 m deep, with swift current, rocky bottom, and presenting reduced riparian vegetation, probably due to anthropogenic activities ( Fig. 5 ). Syntopic species included Ancistrus sp. Characidium aff. zebra Eigenmann , Crenicichla pellegrini Ploeg , Eigenmannia gr. trilineata, Farlowella amazonum (Günther), Gymnotus coropinae Hoedeman , Helogenes marmoratus Günther , Hyphessobrycon sp., Leporinus maculatus Müller & Troschel , Moenkhausia comma Eigenmann , Moenkhausia collettii (Steindachner) , Otocinclus mura Schaefer , Pimelodella cf. howesi , Poptella compressa (Günther) , Satanoperca jurupari (Heckel) and Tatia dunni (Fowler) . The stomach contents of the two (c&s) paratypes included nematoids, chironomids larvae, unidentified vegetal fragments and sediments.

Conservation status. Hyphessobrycon procyon is so far known only from the rio Apuí and one of its tributaries, rio Aripuanã drainage, and its conservation status is uncertain based on the currently available data of its geographic distribution. However, considering that no imminent threats to the species were detected in the area of occurrence of the new species, we suggest that Hyphessobrycon procyon should be classified as Least Concern (LC) according to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Subcommittee, 2014).

Figures

FIGURE 1. Hyphessobrycon procyon new species, holotype (a), MZUSP 115556, 32.2 mm SL, male; MZUSP 117601, paratype, 30.5 mm SL, female (b).

FIGURE 2. Hyphessobrycon procyon, medial view of right side, premaxilla, dentary and maxilla; MZUSP 117642, paratype, 23.8 mm SL. Scale bar: 0.5 mm.

FIGURE 3. Hyphessobrycon procyon, MZUSP 115556, holotype, 32.2 mm SL, male; MZUSP 117601, paratype, 30.5 mm SL, female (b), immediately after capture.

FIGURE 4. Map showing the type-locality (red square) of Hyphessobrycon procyon, rio Juma, a tributary from the rio Aripuanã, rio Madeira basin, Brazil. Symbol represent more than one collected site.

FIGURE 5. Rio Juma, rio Aripuanã drainage, Apuí, Amazonas, Brazil, type-locality of Hyphessobrycon procyon.

Tables

TABLE 1. Morphometric data for holotype and paratypes of Hyphessobrycon procyon, included in number of specimens (n = 29; 5 dimorphic males, 24 females and unsexed juveniles). S. D = Standard Deviation.

Holotype	Range	Median ± S.D.
Standard length (mm) 32.2	20.8-32.6	26.7
Percentages of Standard Length
Depth ato dorsa-fin origin 41.6	34.6-43.7	38.9*2.1
Snout to dorsal-fin origin 37.2	24.6-37.3	30.9*3.6
Snout to pectoral-fin origin 28.6	26.6-31.3	29.2*1.1
Snout to pelvic-fin origin 47.0	45.6-52.0	49.1*1.4
Snout to anal-fin origin 60.9	60.2-66.9	63.7*1.6
Caudal peduncle depth 11.4	9.4-11.9	10.7*0.8
Caudal peduncle length 12.1	9.2-13.7	11.4*0.9
Pectoral-fin length 26.2	18.6-26.2	22.6*1.5
Pelvic-fin length
Females/immature -	18.6-21.9	21.1*1.3
Males 23.9	21.3-23.9	23.2*1.1
Pelvic-fin origin to anal-fin origin 17.1	14.9-20.1	17.0*1.3
Dorsa-fin base length 17.8	14.0-18.5	16.7*0.9
Dorsal-fin length
Females/immature -	32.1-38.8	35.5*1.6
Males 46.8	40.6-49.1	44.4*3.5
Dorsal-fin origin to caudal-fin origin 55.5	48.6-57.1	53.6*1.8
Anal-fin base length 33.0	28.9-33.5	31.3*1.2
Anal-fin length 22.7	18.8-30.9	23.5*2.0
Posterior margin of eye to dorsa-fin origin 38.2	36.0-40.1	38.4*1.0
Head length 26.0	25.0-28.9	27.1*1.0
Percentages of Head length
Horizontal length eye 39.9	39.1-46.4	43.2*1.9
Snout length 26.5	19.0-27.0	24.0*1.9
Least interorbital width 35.7	32.2-37.0	34.3*1.2
Upper jaw length 40.7	35.1-43.1	39.8*1.8