Brachyhypopomus menezesi, Crampton & de Santana & Waddell & Lovejoy, 2016

Crampton, William G. R., Santana, Carlos D. de, Waddell, Joseph C. & Lovejoy, Nathan R., 2016, A taxonomic revision of the Neotropical electric fish genus Brachyhypopomus (Ostariophysi: Gymnotiformes: Hypopomidae), with descriptions of 15 new species, Neotropical Ichthyology (e 150146) 14 (4), pp. 639-790 : 740-741

Brachyhypopomus menezesi , new species urn:lsid:zoobank.org:act:5C81E7C7-4DCE-4EEA-A56F-D0533ACF70E2

( Fig. 34 ; Tables 2-5, 15)

Brachyhypopomus sp. “men”. -Crampton, 2011: 176, table 10.2, species list; 179, figs. 10.2-10.3, phylogeny, geographical and ecological distributions (gymnotiform biology).

Brachyhypopomus electropomus . - Sullivan, 1997: 122 (description in unpublished thesis with disclaimer stating that nomenclatural acts not available, a nomen nudum, name refers also to B. bombilla and B. regani ).

Brachyhypopomus sp. “menezesi ”. - Crampton et al., 2016: 1-66, table 1, 3-4, figs. 1-7, 18-20 (phylogeny, biogeography and ecology of Brachyhypopomus ).

Holotype. MZUSP 87147 , male, 100 mm TL, 75 mm LEA, Brazil, Bahia, 1 km São Marcelo, rio Sapão, affl. rio Preto, rio São Francisco dr., 11°01′02″S, 045°31′50″W, 11 Nov 2002, C. Moreira & J. Nolasco.

Paratypes. 6 specimens, localities from rio São Francisco dr. Brazil . Bahia. MZUSP 40190 , 1 ( CS), 111 mm, mun. Ibiraba, nr. mouth of rio Icatú , ca. 10°33′S, 043°06′W, Sep 1988, M. Rodrigues . Minas Gerais. MCZ 52124, 5 (2 female, 111-112 mm, 3 male, 112-119 mm), rio Pandeiros , ca. 15°42′S, 044°36′W, 1938, W. Schroeder .

Non-types. 7 specimens. Brazil. Minas Gerais (localities from rio São Francisco dr.). MCP 28255 , 5 , 35-56 mm, mun. Claro de Minas, stream at entrance of Claro de Minas , hwy. Guarda-Mor-Vazante, affl. rio Claro , affl. rio Escuro , affl. rio Paracatu , 17°56′07″S, 046°58′28″W . MZUSP 39420 , 2 , 68-71 mm LEA, Lagoa do Tacho [nr. Pirapora], L margin rio São Francisco , ca. 17°20′S, 044°56′W .

Diagnosis. Brachyhypopomus menezesi is diagnosed from congeners by the following combination of characters: accessory electric organ over the opercular region present, vs. absent in all congeners except B. bombilla and B. regani ; dorsal surface with large dark blotches against a lighter background, vs. dorsal surface speckled with small brown chromatophores on a pale background in B. bombilla ; caudal filament length 24.7-33.3% LEA, vs. 11.1-17.9% in B. regani .

Description. Head and body shape, and pigmentation illustrated in Fig. 34 . Meristic and morphometric data for examined specimens presented in Tables 2-5 and 15. Body moderate in depth. Head moderate in length and shallow to moderate in depth. Dorsal profile of head straight to slightly concave from occiput to snout, ventral profile of head approximately straight to slightly concave between operculum and snout, snout truncate to rounded. Eye moderate in size. Upper jaw with moderate sigmoidal angle between premaxillary and maxillary portions in lateral view. Accessory electric organ (AEO) over operculum present and very prominent; skin over AEO completely depigmented; border rounded and very conspicuous. Pectoral fin narrow to moderate in width, pectoral-fin rays 14-16 (no mode, median 15). Precaudal vertebrae 16-17 (mode 16), with 1-2 (mode 2) transitional vertebrae. Anal-fin origin slightly (<0.25 HL distance) posterior to, or near, tip of pectoral fin. Rows of scales above lateral line 6-7 (mode 6). Lateral line continuous. Multiple groove-like depigmented and darkly pigmented epidermal canals form parallel striations either side of lateral line in posterior third of body; striations reaching 1-4 scales (including lateral line series) dorsally, and 1-2 scales ventrally. Epidermal canals flanking lateral line not present in anterior portion of body, do not form a pair of long irregular lines either side of dorsal surface in dorsal portion of flank, and do not form isolated horizontal wavy line midway from lateral line to dorsal midline in midbody or anterior portion of body. Additional multiple parallel fine depigmented epidermal canals running in an anterodorsal to posteroventral direction over body cavity, some of which converge posteriorly to two or three canals running posteriorly for approximately third anal-fin base distance approximately half way from lateral line to proximal edge of anal-fin pterygiophores before fading. Three bilateral columns of electrocytes at anal-fin terminus, and at a mid-point between anal-fin terminus and tip of caudal filament in immature, mature female, and mature male specimens. Electrocytes of hypaxial electric organ extend anterior to anal and urogenital pores and extend into opercular area to form paired accessory electric organ. Caudal filament of moderate length.

Coloration. ( Fig. 34 ). Background light tan to brown. Dorsal region without prominent depigmented pale stripe extending along midline from occipital region to base of caudal filament. Dorsal region mottled with irregular pattern of small, well demarcated, interconnected dark blotches against a homogenous lighter background (contrasting with a uniform speckling of small brown chromatophores against a lighter background in B. bombilla ). Dark mottling extends ventrally across dorsal and ventral flank, with highest density in dorsal portions of flank. Caudal filament darker than body, with some irregular dark markings. Head with evenly scattered dark chromatophores, darker dorsally. Region over accessory electric organ completely depigmented. Eye without prominent suborbital patch, or stripe, of chromatophores/subcutaneous pigmentation. Pectoral and anal-fin membranes hyaline. Pectoral-fin rays hyaline. Anal-fin rays hyaline with light scattering of brown chromatophores. Color in live individuals never observed, but likely similar to preserved specimens.

Size. Small adult size, largest specimen examined 119 mm TL, 83 mm LEA (n = 14). Largest male specimen examined 119 mm TL, 83 mm LEA (n = 4). Largest female specimen examined 112 mm TL, 88 mm LEA (n = 2).

Sexualdimorphism. Noknownsecondarysexualdimorphism.

Geographic distribution. Brazil ( Fig. 27 ). Known only from the middle and upper rio São Francisco drainage, in the states of Bahia and Minas Gerais .

Ecological notes. Geographical coordinates and labels accompanyingtheexaminedmuseumspecimensindicatethat B. menezesi occurs in small rivers and streams, and also lacustrine environments. Stomach contents of one examined specimen comprised aquatic insect larvae – mostly Chironomidae . The ecology of B. menezesi is otherwise unknown.

Co-occurring congeners: None.

Etymology. The specific name is a patronym (noun in the genitive case) in honor of Naércio Aquino Menezes, Brazilian ichthyologist, for his important contributions to Neotropical fish systematics.

Local names. Brazil: tuvira.

Figures

Fig. 34. Brachyhypopomus menezesi. MZUSP 87147, holotype, male, 100 mm TL (head in lateral view, and body in lateral and dorsal view, specimen fixed in formalin and preserved in EtOH); Brazil, rio Sapão, rio São Francisco dr. Note prominent opercular accessory electric organ (pale structure). Scale bars = 5 mm.

Fig. 27. Collection records for Brachyhypopomus gauderio (circles) and B. menezesi (squares). Holotype locations are marked with open symbols. Grey circles refer to suspected anthropogenic introductions of B. gauderio to upper Paraná dr. (see species redescription in text). Elevation data refers to altitude above mean sea level (see Fig. 2 for legend). Note that the most southerly record for B. menezesi is in a headwater of the rio São Francisco, near the drainage divide with rio Paraná headwaters.