Poecilocharax callipterus, Ohara & Pastana & Camelier, 2023

Ohara, Willian M., Pastana, Murilo & Camelier, Priscila, 2023, The monophyly of Crenuchinae and description of two new species of Poecilocharax (Teleostei: Crenuchidae) based on phenotypic and genotypic evidence, Zoological Journal of the Linnean Society 197 (2), pp. 442-473 : 446-454

publication ID	https://doi.org/ 10.1093/zoolinnean/zlac026
publication LSID	lsid:zoobank.org:pub:3F65DD5D-3C73-49A8-88F5-E047CFDEB68B
DOI	https://doi.org/10.5281/zenodo.7624818
persistent identifier	https://treatment.plazi.org/id/784C879E-0267-0A35-FC55-FA88BDC79F31
treatment provided by	Plazi
scientific name	Poecilocharax callipterus
status	sp. nov.

Treatment

POECILOCHARAX CALLIPTERUS SP. NOV.

( FIGS 3–9 View Figure 3 View Figure 4 View Figure 5 View Figure 6 View Figure 7 View Figure 8 View Figure 9 ; TABLE 2 View Table 2 )

Zoobank registration: urn: lsid: zoobank. org:act: A55ADF69-B919-415B-8BAB-38F7516AB9AD.

Holotype: MZUSP 121650 View Materials , male, 30.9 mm SL, BRAZIL, Amazonas State , Apuí , tributary of Rio Canadá , Rio Juma , Rio Aripuanã drainage, Rio Madeira Basin, road AM 174 between Apui and Novo Aripuanã towns, 6º51′36′′S 59º58′36′′W, 140 m above sea level (a.s.l.), 23 June 2015, W. Ohara and V. Abrahão (collectors). GoogleMaps

Paratypes: BRAZIL, Amazonas State, Apuí . MZUSP 117568 View Materials (43, 19.1–31.2 mm SL; 2 C&S, 23.3–28.1 mm SL; 3 MOL, 23.9–29.0 mm SL) ; INPA 59405 View Materials (15, 23.0– 29.6 mm SL) ; MCP 54291 View Materials (15, 21.7–28.1 mm SL) , MNRJ 51747 View Materials (10, 22.7–28.4 mm SL), same data as the holotype GoogleMaps . MZUSP 121653 View Materials (17, 24.6–30.6 mm SL; 3 C&S, 29.1–31.6 mm SL), same locality as the holotype GoogleMaps , 9 October 2016, O. Oyakawa, W. Ohara, M. Pastana and T. Teixeira (collectors) .

Description: Morphometric data are presented in Table 2 View Table 2 . Largest specimen reaching 31.2 mm SL. Body moderately compressed and deep ( Fig. 3 View Figure 3 ). Greatest body depth approximately at vertical through tip of pectoral fin. Dorsal profile convex between tip of snout and posterior region of frontal bone; slightly concave or straight from that point to tip of supraoccipital spine; convex from supraoccipital spine to base of last dorsalfin ray; straight or slightly concave between that point to origin of anterior most dorsal procurrent caudalfin ray. Ventral profile convex between anterior tip of dentary and anal-fin origin; slightly convex at analfin base; almost straight between terminus of analfin base to origin of anteriormost ventral procurrent caudal-fin ray. Body elliptical in cross-section at pectoral-fin origin, broader ventrally and gradually more compressed toward caudal-fin base.

Mouth terminal, jaws vertically aligned anteriorly. Snout gently rounded, shorter than eye diameter. Distal tip of maxilla barely reaching anterior margin of orbit. Orbital margin free. Cheek depth about half of eye diameter. Anterior and posterior nares close to each other, separated by skin flap. Anterior naris tubular and posterior crescent-shaped. Frontals concave anteriorly, with wide depression between orbits extending from posterior portion of mesethmoid bone to anterior portion of epiphyseal branch of supraorbital canal ( Fig. 4 View Figure 4 ). Concavity allocating frontal organ. Each frontal containing one relatively large foramen for passage of nerve branch ophthalmicus superficialis that innervates the organ. Foramen located medial to supraorbital canal of cephalic lateral line, anterior to epiphyseal branch of supraorbital canal ( Fig. 4 View Figure 4 ). Supraorbital bone absent. Infraorbitals one to six present ( Fig. 5 View Figure 5 ), with infraorbitals three and four occasionally fused to each other; antorbital bone located anterodorsally to first infraorbital. Pseudotympanum present, underneath third to fifth scales of longitudinal line.

Dentary teeth in one row with seven to 13 (5) conical or tricuspid teeth. Premaxillary teeth in single row with ten or 11 (5) conical to tricuspid teeth. Premaxillary and dentary teeth increasing in size toward symphysis. Maxillary teeth absent ( Fig. 6 View Figure 6 ). Ectopterygoid with small teeth. Branchiostegals five (5); four attached to anterior ceratohyal and one to posterior ceratohyal. First arch with three (5) gill rakers on hypobranchial, seven (1), eight (1), nine (2) or ten (1) on ceratobranchial, one (5) on cartilage between ceratobranchial and epibranchial, and six (1) or eight (4) on epibranchial. Gill rakers slightly shorter than brachial filaments. Supraneurals three (5), small and rod-like dorsally positioned and anterior to first neural spine (5).

Laterosensory system developmentally truncated, tubules opening in individual pores (i.e. never forming subpores). Supraorbital canal associated with nasal, frontal and parietal bones. Epiphyseal and parietal branch of supraorbital canal present ( Fig. 4 View Figure 4 ). Supraorbital lacking connection to otic canal, falling short near posterolateral margin of frontal bone. Infraorbital canal developmentally truncated, restricted to infraorbital plates 1, 2 ( Fig. 5 View Figure 5 ) and variably associated with infraorbital plates 5, 6. Otic canal present, associated with anterior portion of pterotic. Post-otic canal running along pterotic, extrascapular, post-temporal and supracleithrum. Supratemporal canal associated with extrascapula and posterior margin of parietal bone, running dorsomedially and opening in a pore near cranial fontanel. Preopercular canal extending along entire extension of pre-opercular bone, continuous with mandibular canal. Mandibular canal associated with the anguloarticular and dentary bones.

Scales cycloid, circuli distributed over entire scale surface. Two to four parallel and well-defined radii present on posterior scale surface. Trunk lateral-line perforating a single scale, either fifth (3) or sixth* (19) scale of the longitudinal series ( Fig. 7 View Figure 7 ). Perforated scale inconspicuous or covered by skin in some specimens. Longitudinal scale series, including perforated scale, 25 (1), 26 (3), 27 (8), 28* (13) or 29 (1). Horizontal scale rows above lateral line four* (26). Horizontal scale rows below lateral line three* (26). Scale rows around caudal peduncle 14* (26). Predorsal scales series six (8), seven* (14) or eight (2). Isthmus scaled. Scales between anus and anal fin, none (1), one* (18) or two (6). Superficial neuromasts arranged vertically on basal portion of each scale, more conspicuous on anterior half of body ( Fig. 8 View Figure 8 ).

Pectoral-fin rays ii, nine (2) or 10* (22). Tip of longest pectoral-fin ray slightly anterior to vertical through dorsal-fin origin. Pelvic-fin rays i,seven* (24). Tip of longest pelvic-fin rays slightly anterior to vertical through insertion of last dorsal-fin ray. Dorsal-fin rays iii,13 (1), iii,14 (2), iv,12 (1), iv,13* (13) or iv,14 (7). Dorsal-fin ray length variable ( Figs 3 View Figure 3 , 9 View Figure 9 ; see ‘sexual dimorphism’). Dorsal-fin origin nearer snout than caudal-fin base, slightly anterior to vertical through pelvic-fin origin. First dorsal-fin pterygiophore located behind neural spine of 18 th (5) vertebra. Anal-fin rays ii,seven (5), ii,eight (9), iii,seven* (8), iii,eight (3) with variable length ( Figs 3 View Figure 3 , 9 View Figure 9 ; see ‘sexual dimorphism’). Anal-fin origin posterior to vertical through base of last dorsal-fin ray. Single row of one to three scales covering base of anteriormost anal-fin rays. First anal-fin pterygiophore located behind neural spine of 18 th (5) vertebra. Principal caudal-fin rays i8,8i (1), i9,8i* (25), i9,7i (1) or i10,8i (2). Caudal fin with one to three large scales covering basal portion of each lobe. Dorsal procurrent caudal-fin rays five (1) or six (4), and ventral procurrent caudal-fin rays four (1) or five (4). Hypurals one and two fused to each other; hypurals five and six fused to each other in some specimens (2); hypurals three and four always autogenous. Adipose fin absent. Total vertebrae 29 (1) or 30 (4); precaudal vertebrae 19 (5), caudal vertebrae ten (1) or 11 (4).

Colour in alcohol: Overall background coloration of head and body beige to brown, darker dorsally ( Fig. 3 View Figure 3 ). Snout, premaxilla, tip of dentary, maxilla, antorbital and infraorbitals one and two densely covered by small, dark chromatophores. Ventral portion of head, cheeks, gular and opercular regions with scattered chromatophores. Eyes mostly dark, with brown pigments surrounding pupils. Suborbital stripe absent. Guanine deposits on head not visible in alcohol preserved specimens. Dark chromatophores densely distributed along dorsal and dorsolateral scale rows. Scales of anterior-dorsal half of body with chromatophores disposed vertically, mostly on anterior margin of scales, forming small, dark blotches on each scale. Scale borders forming a conspicuous reticulate pattern on anterior-dorsal half of body. Ventral portion of the body lighter, abdominal region lacking pigment, except for few sparse dark chromatophores. Body somewhat mottled, having nine to 12 conspicuous dark blotches. First blotch somewhat round, variably present immediately posterior to the opercle, followed by two other blotches. Midline of body often having blotches irregular in shape with undefined borders. A series of two to five vertically elongated, dark blotches encompassing one scale horizontally and three to four scales vertically, positioned below the dorsal-fin base. Midbody with two to three dark blotches: one located at the abdominal region, one or two at the anal-fin base. Midbody blotches highly variable in number, position and conspicuity among specimens, with blotches occasionally forming a discontinuous dark stripe; none to four dark spots or blotches positioned above anal-fin base. Caudal peduncle with one conspicuous dark spot, located on ventral half of peduncle, near the base of ventral caudal-fin rays (referred hereafter as asymmetrical caudal-peduncle spot), encompassing two or two and a half scales horizontally and one to one and a half vertically ( Fig. 3 View Figure 3 ). Spot remarkably similar to that present in Crenuchus spilurus (see Discussion).

Dorsal-fin coloration sexually dimorphic. Dorsal fin mostly dusky in adult males, with dark pigment more concentrated distally on rays and interradial membranes; dorsal-fin filament densely pigmented. Remaining dorsal-fin area with melanophores sparsely distributed, more concentrated in the distal portions of the fin. Posteriormost dorsal-fin rays hyaline. Dorsal fin of females and immature individuals has less pigmentation, with melanophores sparsely distributed on border of rays, more concentrated on distal half of anteriormost rays; dorsal-fin filament, whenever present, short and dark. Pectoral fins predominantly hyaline in both sexes, with few scattered dark chromatophores present along margins of rays. Pelvic fin varying from hyaline in females and juveniles or dusky in adult males, with scattered chromatophores along fin-rays and membranes. Anal-fin coloration sexually dimorphic; adult males with dusky anal-fin, and dark chromatophores along border of rays and membranes. One horizontal dark stripe present distally on the anal-fin, encompassing the first five anal-fin rays. Dark stripe contrasting with an unpigmented anal-fin margin. Anal fin of females and immature specimens considerably less pigmented. Caudal fin with concentration of dark chromatophores on upper and lower caudal-fin base, and a series of small and elongated spots along interradial membrane of middle caudal-fin rays. Caudal-fin spots more numerous in adult males.

Colour in life: Overall body coloration yellow to red, darker dorsally ( Fig. 9 View Figure 9 ). Abdominal region yellow with silvery hue. Adult males with a more vivid coloration. Dark blotches on body as described in ‘Colour in alcohol’, usually visible in live specimens. Guanine deposits on cheeks, ventral portion opercular bone and along sub- and interopercle. Lower half of opercle and infraorbitals two to four silvery, golden or red. Upper half of opercle transparent, red gill filaments visible through bone in some individuals. Upper and lower jaw mostly yellow; orange hue present in large adult males.

Dorsal-fin coloration sexually dimorphic ( Fig. 9 View Figure 9 ). Adult males with dorsal fin orange to red along first 12 to 14 dorsal-fin rays, chromatophores more concentrated on interradial membranes. Tip of dorsal-fin filament strongly red pigmented. Females and immature specimens of both sexes with dorsal fin mostly yellow, with chromatophores concentrated on fin-rays. Pectoral fins predominantly pale orange to yellow in both sexes. Pelvic fins yellow to orange, more intensely coloured in adult males. Anal-fin coloration sexually dimorphic. Adult males with orange to red fin, chromatophores concentrated on interradial membranes of first nine anal-fin rays; and with an evident horizontal red stripe located on the leading margin of first five to six anal-fin rays. Females and immature specimens of both sexes with anal fin yellow to orange, less vivid than adult males, with red stripe absent or inconspicuous. Caudal fin pale red to yellowish in both sexes.

Sexual dimorphism: Dorsal-fin filament length sexually dimorphic. Dorsal-fin height of adult males ranging from 51.3 to 67.5% of SL with a long dorsal-fin filament projecting from the eighth to 11 th dorsal-fin rays. In some specimens, depressed filament reaching the proximal half of the upper caudal-fin lobe ( Figs 3 View Figure 3 , 9 View Figure 9 ). Adult females with much shorter dorsal-fin filaments, projecting from the eighth to tenth dorsal-fin rays, with tip of filament never reaching base of caudal-fin rays. Adult males with longer anal-fin, tip of longest ray reaching to distal half of ventralmost principal caudalfin ray. Adult females with shorter anal-fin rays, tip of longest ray never reaching principal caudal-fin rays ( Figs 3 View Figure 3 , 9 View Figure 9 ).

Adult males more vividly coloured than females ( Fig. 9 View Figure 9 ). Coloration in live orange to red, with dorsal and anal fins more intensely pigmented. Adult males with inconspicuous red stripe on leading margin of dorsalfin filaments and conspicuous band along first six analfin rays ( Fig. 9A View Figure 9 ). Females and immature specimens of both sexes paler, with overall yellow to gold coloration, and dorsal, pelvic and anal fins yellow to orange. Dorsal and anal fins lacking red stripe on leading margin (see ‘Colour in life’ section for further details) ( Fig. 9B View Figure 9 ). Bony processes were not observed on fin-rays of either sex.

Etymology: The specific name callipterus is Latinized from the Greek κάλλη [kalli], beauty, and πτερων [pteron], feather or wing, in reference to the vivid coloration of the dorsal-fin of adult males. It is a declinable adjective.

Geographic distribution: Poecilocharax callipterus is known from the type locality, a black water tributary of the Rio Juma , in the Rio Aripuanã drainage, Rio Madeira Basin , Apuí Municipality , Amazonas State, Brazil ( Fig. 10 View Figure 10 ).

Ecological notes: The type locality of Poecilocharax callipterus is a small, black-water stream ( Fig. 11 View Figure 11 ). The stream is located at an elevation of 140 m, is 1–3 m wide, 0.3–1.0 m deep, with slow-flowing water and a predominantly rocky substrate. The stream runs across a small Cerrado (= savannah) enclave into the Amazon Forest. Specimens were collected during daytime and were in low abundance. Different environments and habitats were explored, but the new species was captured specifically among aquatic grasses or roots near the margins. Schools were not observed. Individuals of P. callipterus were observed during the night in deeper portions of the stream (1 m) and near the marginal vegetation or between subaquatic roots of riparian vegetation ( Fig. 11 View Figure 11 ). Several small streams were sampled in two field expeditions carried out in 2015 and 2016, but only the type locality had aquatic vegetation and a rocky bottom. Thus, we infer that P. callipterus may have specific habitat requirements. At the type locality of P. callipterus , characids are absent and this is apparently the only species to forage the medium-upper water column. Fish species sampled syntopically in the type locality were Callichthys callichthys (Linnaeus, 1758) , Erythrinus erythrinus (Bloch & Schneider, 1801) and three unidentified species of Aequidens Eigenmann & Bray, 1894 , Brachyhypopomus Mago-Leccia, 1994 and Lepthoplosternum Reis, 1997 . The stomach content analysis of five paratypes revealed the presence of filamentous algae, nematodes, chironomids, Cladocera , sediment and sand. One male and two female specimens collected in October had gonads moderately developed.

Conservation assessment: The risk of extinction for this species is preliminarily assessed as critical. Poecilocharax callipterus is a species of restricted geographical range, known only from one small, black-water tributary of the Rio Juma (Rio Aripuanã drainage), near the city of Apuí. The new species was discovered in a stream that crosses the highway AM-174 (linking Apuí and Novo Aripuanã), a region surrounded by a small and relatively degraded forest area currently being occupied by pasture. There are three Conservation Units surrounding the type locality (Floresta Nacional do Jatuarana to the south, Parque Nacional do Acari to the east and Floresta Nacional do Aripuanã to the west), and some still preserved, unprotected areas near the type locality. However, the new species was not found elsewhere other than the type locality, despite intense collecting efforts, and the presence of P.callipterus within these Conservation Units or in surrounding areas remains uncertain but seems unlikely. Sampling activities took place in 2015 and 2016, and at that time, the type locality did not present signs of silting, water turbidity and erosion on the banks ( Fig. 11 View Figure 11 ). However, the territory of Apuí has been intensely impacted by deforestation ever since the discovery of the new species, and it is currently ranked in second place in a list of Brazilian municipalities with greatest loss of native forest ( Fonseca et al., 2021). The Area of Occupation of the new species is estimated as 4 km 2 (B2). A continuous decline in the habitat quality is expected and inferred based on erosion, silting and increased turbidity, as results of continued high deforestation in the region. The number of locations is one. There are no estimates of population size or population decline. For these reasons, P. callipterus is tentatively assessed as Near Threatened (NT) approaching Critically Endangered (CR) by criterion B2ab(iii) according to the International Union for Conservation of Nature (IUCN) categories and criteria (IUCN Standards and Petitions Sub-Committee, 2019).