Hemigrammus changae, Ota & Lima & Hidalgo, 2019

Ota, Rafaela P., Lima, Flávio C. T. & Hidalgo, Max H., 2019, Description of a new Hemigrammus Gill (Characiformes: Characidae) from the río Madeira basin in Peru and Bolivia, Zootaxa 4577 (2), pp. 335-347 : 336-341

Hemigrammus changae , new species

( Figs. 1–3 )

Hemigrammus cf. lunatus (not Durbin): Mirande, 2018: 9 (phylogenetic relationships; based on a specimen from lot MUSM 3927).

Holotype: MUSM 663836 , 29.9 mm SL, Peru, Departamento Madre de Dios, Puerto Maldonado, Aguajal Cicra , Aguajal Pozo Minero , 12 o 33'48"S 70 o 07'03"W, 9 Dec 2003, M.H. Hidalgo.

Paratypes: All from Peru. Departamento Madre de Dios: MUSM 21644 , 34 , 1 c&s, 22.3–28.7 mm SL ;

CAS 246141 , 10 , 23.1 – 27.6 mm SL ; FMNH 138666 , 10 , 24.1 – 27.8 mm SL ; MCZ 173322 , 8 , 24.1 – 27.1 mm SL ; ZUEC 17027 , 10 , 23.5 – 26.7 mm SL; same data as holotype . MUSM 3927 , 151 , 3 c&s, 16.0–24.0 mm SL ; ZUEC 17029 , 7 , 3 c&s, 19.1–22.3 mm SL, Zona Reservada Tambopata Candamo, La Colpa, cocha tributary of río Tambopata , ca. 12°55'S 69°15'W, 22 Aug 1992, F. Chang & J. Icochea . MUSM 5600 , 14 , 21.0– 26.4 mm SL, Zona Reservada Tambopata Candamo, Las Piedras, quebrada 2 km from lago Sandoval , ca. 12°36'S 69°03'W, 23 Jan 1990, H. Ortega, F. Chang & F. Rodriguez . MUSM 8563 , 9 , 19.5 – 23.8 mm SL, Puerto Maldonado, La Cachuela , 12°34'45"S 69°11'13"W, 12 March 1995, H. Ortega . MUSM 21701 , 18 , 10.8 – 26.3 mm SL, Puerto Maldonado, Aguajal Satélite, Aguajal Aguas Negras , 12°39'26"S 69°26'29"W, 22 Jan 2004, M.H. Hidalgo . MUSM 21823 , 58 , 10.2 – 27.9 mm SL, Puerto Maldonado, Aguajal Aguas Negras, Aguajal Pozo Minero , 12 o 38'10"S 69 o 25'36"W, 21 Jan 2004, M.H. Hidalgo . INPA 57938 , 10 , 4 c&s, 23.6–28.0 mm SL ; MUSM 21992 , 126 , 10.5 – 29.3 mm SL ; MUSM 22018 , 83 , 12.2 – 30.4 mm SL, Puerto Maldonado, Aguajal Este, lower río Madre de Dios, San Francisco , 12 o 28'11"S 68 o 56'04"W, 20–21 Feb 2004, M.H. Hidalgo . MUSM 22055 , 27 , 16.0– 30.3 mm SL ; MUSM 22068 , 149 , 10.6 – 29.6 mm SL ; ZUEC 17028 , 4 , 19.1 – 29.7 mm SL, Puerto Maldonado, Puerto Pardo, Aguajal Tripa , lower río Madre de Dios, 12°29'34''S 68°57'31''W, 22–23 Feb 2004, M.H. Hidalgo . MUSM 22135 , 40 , 9.8 – 27.3 mm SL, Puerto Maldonado, San Francisco, Aguajal Trigoso , lower río Madre de Dios, 12 o 27'58"S 68 o 52'53"W, 28 Feb 2004, M.H. Hidalgo . MUSM 22040 , 58 , 13.5 – 25.3 mm SL, Puerto Maldonado, San Francisco, Aguajal Pozo Paiche , lower río Madre de Dios, 12 o 29'05"S 68 o 57'09"W, 22 Feb 2004, M.H. Hidalgo. Departamento Puno : MUSM 52037 , 1 , 21.9 mm SL, Cocha Wiener, río Heath , 13 o 19'11"S 68 o 52'32"W, 18 Jun 2013, J. Chuctaya et al .

Non-types: Peru, Departamento Madre de Dios: MUSM 2919 , 24 , 14.8 – 23.5 mm SL, Zona Reservada Tambopata Candamo, La Colpa, Quebrada Grande, tributary of río Tambopata , ca. 12°55'S 69°15'W; 31 Aug 1992, F. Chang. MUSM 22094 , 10 , 10.3 – 13.5 mm SL, Puerto Maldonado, Aguajal Oeste , tributary of río Madre de Dios, 12°28'40"S 68°58'18"W, 25 Feb 2004 , M.H. Hidalgo. MUSM 22112 , 25 , 14.1 – 19.1 mm SL, Puerto Maldonado, Aguajal Gamitana , 12°27'08"S 69°00'32"W, 26 Feb 2004 , M.H. Hidalgo. MUSM 25387 , 41 , 16.5 – 32.1 mm SL, Tahuamanu, río Manuripe, Cocha Macana , ca. 11°49'S 69°32'W, 12 Jul 2004 , M.H. Hidalgo et al. MUSM 52701 , 1 , 20.4 mm SL, Mavila, cocha tributary of río Manuripe , 11°55'37"S 69°06'51"W, 23 Jul 2003 , M.H. Hidalgo et al. MUSM 52699 , 1 , 25.5 mm SL, Manu, Quebrada Carachama, tributary of río Amiguillos , tributary of río Los Amigos , 12°26'40"S 70°15'43"W, 19 Jun 2004 , M.H. Hidalgo et al. Bolivia, Departamento Beni: USNM 305661 , 7 , 20.9 – 22.3 mm SL, Arroyo Aguas Negras, tributary of río Curiraba, 3 km above mouth, 12 km N El Porvenir Biological Station, 40 km E San Borja , río Mamoré basin, ca. 14°55'S 66°17'W, 1 Sep 1987 , W.C. Starnes & T. Munroe. MHNG 2228.086 , 8 , 22.0–25.0 mm SL, tributary of río Chapare, 50 km from confluence with río Mamoré , ca. 15°22'S 65°2'W, 21 Jun 1982 , L. Lauzanne & G. Loubens. Departamento Cochabamba: MHNG 2180.097 , 5 , 23.6 – 27.8 mm SL, río Chapare, "Hoffman Lagune" below Todos Santos , ca. 16°50'S 65°17'W, 7 Oct 1966 , K.H. Lüling. Departamento Santa Cruz: MHNG 2228.075 , 2 , 11.3 – 19.5 mm SL, río Yapacani, near Yapacani, tributary of río Grande , ca. 17°23'S 63°51'W, Sep 1983 , W. Staeck & H. Linke. MHNG 2270.056 , 2 , 21.5 – 23.8 mm SL, same locality and collectors as MHNG 2228.075 , 19 March 1985 .

Diagnosis. Hemigrammus changae differs from most congeners except from H. barrigonae , H. lunatus , H. machadoi , and H. ulreyi by possessing a wide dark horizontal stripe across the eye (vs. eye stripe absent or, when present, vertical). The new species can be additionally distinguished from all congeners, with the exception of Hemigrammus barrigonae , H. boesemani , H. geisleri , H. lunatus , H. machadoi , H. mimus , and H. ulreyi , by presenting a well-defined narrow dark stripe at the basis of the anal fin (vs. absence of dark stripe at the basis of anal fin). It can be distinguished from H. boesemani , H. geisleri , and H. mimus by lacking a blotch on caudal peduncle or any distinct patch of pigmentation on caudal fin (vs. a dark blotch on caudal peduncle or at the base of caudal fin present). Hemigrammus changae can be additionally diagnosed from Hemigrammus geisleri and H. mimus by lacking a pseudotympanum (vs. presence of a conspicuous pseudotympanum). The new species can be diagnosed from H. barrigonae , H. lunatus , and H. machadoi by presenting an oval, horizontally elongated humeral blotch (vs. a diffuse, vertically-elongated humeral blotch in H. barrigonae ; a small rounded humeral blotch in H. lunatus ; a rectangular, vertically-elongated blotch in H. machadoi ). Hemigrammus changae can be distinguished from H. ulreyi by the absence of a patch of dark pigmentation on the basis of anteriormost dorsal-fin rays (vs. presence of a patch of dark pigmentation on the basis of anteriormost dorsal-fin rays). The new species can be additionaly distinguished from H. ulreyi , as well as from H. barrigonae , by lacking a conspicuous midlateral stripe (vs. presence of a conspicuous midlateral stripe). Hemigrammus changae can be additionally diagnosed from H. machadoi by presenting 6–7 gill-rakers on upper branch and 10–12, mode 12, on lower (vs. 4–5, and 9–10, mode 9, respectively), and more vertebrae (34–35 vs. 32–33), and from H. lunatus by presenting a higher number of cusps on maxillary largest tooth (5 vs. 1–3).

Description. Morphometric data summarized in Table 1. Body compressed, moderately high; greatest body depth anterior to dorsal-fin origin. Dorsal profile of head slightly convex from tip of snout to anterior naris; straight to gently concave from latter point to tip of supraoccipital spine. Dorsal profile of body slightly to moderately convex from tip of supraoccipital spine to dorsal-fin origin; posteroventraly slanted from latter point to adipose-fin origin and slightly concave along caudal peduncle. Ventral profile of body convex from tip of dentary to anal-fin origin, posteroventraly slanted along anal-fin base. Ventral profile of caudal peduncle slightly to moderately concave.

TABLE I. Morphometric data of Hemigrammus changae , new species. N = Number of specimens, and SD = standard deviation; all including the holotype .

Mouth terminal; jaws equal, isognathous. Maxillary slightly curved, distal tip extending beyond vertical through anterior margin of eye. Premaxillary teeth in two rows, outer row composed by 3*(40) or 4(18) tri- to pentacuspid teeth, central cusp longer; inner row with 5*(78) penta- to heptacuspid teeth teeth, central cusp longer. Maxillary with 2(8) to 3(1) tri- to pentacuspid teeth along anteroventral margin, anteriormost tooth broader and always pentacuspid. Dentary with 9(1), 10(1), 11(3), 12(2), 13(1), or 15(1) teeth, anteriomost four teeth larger than remaining, with 5–7 cusps, central cusp longer, then gradually decreasing in size, 1–2 pentacuspid teeth, and remaining 4–9 tri- or unicuspid, small teeth ( Fig. 2 ).

Scales cycloid. Lateral line incomplete, slightly curved ventrally, with 6(7), 7(9), 8*(15), 9(13), 10(8), or 11(2) pored scales; longitudinal series including perforated scales 29(1), 30(1), 31*(5), 32(8), 33(19), 34(13), or 35(7). Scales rows between dorsal-fin origin and lateral line 5*(54); 3*(23) or 4(31) between lateral line and pelvic-fin insertion. Predorsal scales 9(4), 10*(32), or 11(18). Anal sheath along anal-fin base with 5 or 6 scales in a single row, covering base of first unbranched to fourth branched anal-fin rays. Circumpeduncular scales 10(41), 11*(7) or 12(6). Caudal-fin scales covering approximately basal third of upper and lower caudal-fin lobes margins, gradually decreasing in size.

Dorsal-fin rays ii,9*(54), first unbranched ray nearly one-third of second unbranched ray length; small ossification anterior to first unbranched ray present in all six c&s specimens examined. Dorsal-fin distal margin straight. Dorsal-fin origin at midbody or slightly behind this point; base of posteriormost dorsal-fin ray slightly behind vertical through anal-fin origin. Insertion of first dorsal-fin pterygiophore posterior to neural spine of 9th(6) vertebra. Adipose fin present. Pectoral-fin rays i,10*(52) or 11(1). Pelvic-fin rays i,7*(53), pelvic-fin origin ahead of vertical through dorsal-fin origin; tip of longest ray exceeding anal-fin origin. Anal-fin rays iv, 20(4), 21(4), 22*(11), 23(17), 24(15), or 25(2); last unbranched ray to fifth branched ray longest, remaining rays gradually decreasing in size to anal-fin terminus, forming a conspicuous anterior fin lobe. Last anal-fin pterygiophore insertion behind hemal spine of 14(1) or 15(5) caudal vertebrae. Caudal fin forked, lobes slightly pointed, equal in size. Principal caudal-fin rays i,17,i*(45); dorsal procurrent caudal-fin rays 10(4) or 11(3); ventral procurrent caudal-fin rays 7(2) or 8(5). Vertebrae 33(2) or 34(5). Supraneurals 4(6) or 5(1). Branchiostegal rays 4(5). Upper branch of gill-rakers 6(4) or 7(1), lower branch 10(9), 11(18) or 12(20).

Color in alcohol. Overall body ground coloration light tan. Anterior portion of lower jaw, maxillary, first infraorbital, snout and dorsal portion of head with intense concentration of small dark chromatophores, imparting an overall darker color. Gular region and infraorbitals clearer; third infraorbital and opercle series silvery in specimens retaining guanine pigmentation.

Opercle and infraorbitals with scattered, relatively large dark chromatophores. Eye with a broad dark longitudinal midlateral stripe (not discernible in specimens preserved for a long period in formalin). Longitudinal dark stripe along midline of body present, very faint and narrow, originating after small concentration of dark chromatophores posterior to humeral blotch and extending up to approximately vertical through middle of caudal peduncle or slightly behind this point.

Scales from dorsal region of body, in some specimens almost all scales on body ( Fig. 1C ), posteriorly bordered with dark chromatophores, forming a subtle reticulate pattern. Dark humeral blotch conspicuous, roughly oval, extending horizontally from second through fifth lateral-line scales, and vertically from lateral line to one row above lateral line to one scale row above it. Dark chromatophores below midlateral line arranged along margins of hypaxial muscles bundles from area above anal fin to caudal peduncle. Narrow, very conspicuous dark stripe along anal-fin basis. Fins hyaline, with scattered dark chromatophores, more numerous on dorsal- and anal-fins.

Color in life. Based on pictures of living specimens (not preserved) collected at the río Madre de Dios basin. Head and abdominal region silvery. Body olive-grey, translucent. A narrow midlateral iridescent green stripe, running from humeral blotch to caudal peduncle. Fins hyaline, with a yellow hue.

Sexual dimorphism. Anal-fin hooks were observed in males of Hemigrammus changae collected in August (MUSM 3927, 1, 23.7 mm SL), December (ZUEC 17027, 4, 22.2–23.6 mm SL; FMNH 138666, 2, 24.0– 24.5 mm SL; MCZ 173322, 1, 23.5 mm SL; CAS 246141, 3, 23.5–24.0 mm SL), or February (INPA 57938, 2, 23.0– 23.1 mm SL; MUSM 22018, 5, 23.3–25.0 mm SL; and MUSM 22040, 2, 23.0– 23.3 mm SL). Anal fin with 7–11 tiny hooks, arranged over the last unbranched ray and anteriormost 3–5 branched fin rays, one pair per ray segment. Pelvic-fin hooks were not observed in any specimens. Larger specimens (equal or above 26.0 mm SL) always lack anal-fin hooks and presumably are all females, which consequently are inferred to grow larger than males (the largest specimen examined with anal-fin hooks has 25.0 mm SL, MUSM 22018).

Distribution. Hemigrammus changae is so far known from the río Madre de Dios and from the río Mamoré basins, upper río Madeira basin, in southeastern Peru and Bolivia ( Fig. 3 ). The new species is apparently endemic from the freshwater ecorregion Mamoré-Madre de Dios Piedmont ( Abell et al., 2008).

Ecological notes. Most localities from where Hemigrammus changae is known are slow-flowing streams at "aguajales" (wetlands dominated by Mauritia flexuosa palms). These streams typically possess black water, a large amount of decayed organic matter, and are typically shallow. The type locality was a former a gold mining area that is in the process of recovery due to the implantation of a private conservation concession. Hemigrammus changae is also recorded from oxbow lakes and, in Bolivia, from lakes and streams at the llanos (seasonally flooded savannahs). The species is sympatric, and in some localities syntopic with Hemigrammus lunatus , but the latter species is more commonly found in floodplain lakes from white water rivers, a type of habitat where H. changae is apparently uncommon.

Etymology. The specific name honors the late Fonchii Ingrid Chang Matzunaga, a Peruvian ichthyologist, from Chinese and Japanese ancestry, born on April 30, 1963 in Lima, Peru, who drowned when the boat she was in capsized on August 15, 1999, during an expedition at río Pastaza, Peru. We dedicate to her the new species as a tribute for her considerable contribution in surveying the fishes of her native country, in the relatively little time she was active, which included collecting part of the material herein examined of H. changae . A genitive noun.

Figures

FIGURE 1. Hemigrammus changae. (A), MUSM 663836, 29.9 mm SL, holotype; (B) CAS 246141, 27.2 mm SL, paratype; and (C) MUSM 22055, 28.1 mm SL, paratype: all from Peru, Madre de Dios, río Madre de Dios basin.

FIGURE 2. Medial view of right side of upper and lower jaws of Hemigrammus changae, INPA 57938, paratype, 25.4 mm SL. Scale bar = 0.5 mm.

FIGURE 3. Map of central-western South America showing the distribution of Hemigrammus changae: red star represents type locality, red circles represent the paratypes localities, yellow circles represent the non-types localities, and black circles represent the supplementary material localities.