Acestrocephalus nigrifasciatus, Menezes, 2006

Menezes, Naércio A., 2006, Description of five new species of Acestrocephalus Eigenmann and redescription of A. sardina and A. boehlkei (Characiformes: Characidae), Neotropical Ichthyology 4 (4), pp. 385-400 : 395-397

publication ID

https://doi.org/ 10.1590/S1679-62252006000400002

persistent identifier

https://treatment.plazi.org/id/03B55E5E-267E-5A4E-8E8C-F9024F2EF986

treatment provided by

Carolina

scientific name

Acestrocephalus nigrifasciatus
status

sp. nov.

Acestrocephalus nigrifasciatus View in CoL , new species Fig. 12 View Fig

Holotype. MCP 30420 (83 mm SL), Brazil, Mato Grosso: Porto dos Gaúchos, rio Arinos, rio Tapajós basin, 11º31’51"S, 57º25’8"W, by R. E. Reis, L. R. Malabarba, E.H.L. Pereira, V. A. Bertaco & A. R. Cardoso, 19 Jan 2002. GoogleMaps

Paratypes. MCP 39930, 9 View Materials , 64-93 mm SL, taken with holotype . MZUSP 62845 View Materials , 1 View Materials , 85 mm SL, Brazil, Mato Grosso, rio Juruena, about 1 kilometer above mouth of rio Arinos , by F.A. Machado et al., 25-26 July 1997 ; MZUSP 62847 View Materials , 1 View Materials , 63 mm SL, ilha do Túlio, rio Arinos about 3 kilometers before emptying into rio Juruena , by F.A. Machado et alii, 24-25 July 1997 .

Diagnosis. Acestrocephalus nigrifasciatus has the same color pattern ( Fig. 12 View Fig ) and eye size ( Fig. 4 View Fig ) of A. sardina ( Fig. 3 View Fig ), distinct from all other species of Acestrocephalus . A. nigrifasciatus , however, has more scale rows above (13-14 vs 10-12) and below (12-13 vs 10-12) lateral line. The muscular hiatus of the pseudotympanum in A. nigrifasciatus ( Fig. 5e View Fig ) is longer and narrower than that of A. sardina ( Fig. 5a View Fig ) and the fibers of the obliquus inferioris muscle are not visible as in the latter species.

Description. Morphometrics of holotype and additional specimens presented in Table 12. Body moderately large (SL=64.0-93.0 mm). Body form, dorsal and ventral body profiles, shape of snout and mouth and extension of maxilla as in A. sardina .

Dorsal fin rays ii, 9 in all specimens, n=12, including holotype. Posterior most ray unbranched, n=12. Adipose fin present. Anal-fin rays iv,28 (iv or v, usually iv unbranched, branched rays mean=29, range 27-31, n=12, posterior ray split to its base and counted as 1). Moderately developed anal-fin lobe including anterior unbranched rays and first 6-7 branched rays.Anal fin of six sexually mature males with bilateral hooks on posterior anterior branched rays. One specimen (MCP 30420, 79 mm SL) has the first 15 branched rays bearing hooks. Number of hooks per ray decreasing from anterior most to posterior most rays (8 hooks on first, 17 on second, 7 on seventh, 3 on 13th and 1 on 15th). Pectoral-fin rays i,15 (anterior unbranched rays i, n=12, branched rays mean 14.6, range 14-15, n=12). Posterior tips of longest pectoral-fin rays reaching slightly beyond pelvic-fin origin. Pelvic-fin rays i,7, n=12. No hooks on pelvic-fin rays of sexually mature males. Distal tips of longest pelvic-fin rays reaching anterior border of anus. Principal caudal-fin ray count 10/9, n=12.

Lateral line complete, perforated scales 74 (mean=72.6, range 70-75, n=12). Scale rows above lateral line 13 (men=13.4, range 13-14, n=12). Scale rows below lateral line 13 (mean=12.6, range 12-13, n=12). Scale rows around caudal peduncle 23 (mean=23.1, range=23-24, n=12).

Shape, size and arrangement of teeth on premaxilla, maxilla and dentary as in A. sardina . Outer row small conical teeth on premaxilla 7 (mean=7.2, range 6-8, n=12). Maxillary teeth 41 (mean=42.4, range 40-46, n=12), with no clear tendency to increase in number with an increase in standard length ( Fig. 6 View Fig ). Posterior row dentary teeth 31 (mean=30.1, range 27-34, n=12). Inner row dentary teeth 11 (mean=10.2, range 8-12, n=12).

Vertebrae 37 (mean=37.4, range 37-38, n=11). Total number of gill rakers on first gill-arch 8 (mean=7.2, range 7-8, n=12).

Muscular hiatus of pseudotympanum ( Fig. 5f View Fig ) reduced, much longer than deep, exposed first pleural rib scarcely visible, second pleural rib slightly more visible, but obliquus inferioris muscle fibers entirely covered by ventral fibers of obliquus superioris.

Color in alcohol. Similar to that of A. sardina , but dark lateral body stripe broader along entire length (compare Figs. 3 View Fig and 12 View Fig ) darker anteriorly; diffuse dark blotch on mental area of lower jaw less conspicuous.

Distribution. Acestrocephalus nigrifasciatus is known from the rios Arinos and Juruena, and rio Tapajós basin ( Fig. 8 View Fig ) in the state of Mato Grosso.

Etymology. The first part of the species name niger is Latin for black and the second part fasciatus is also derived from the Latin word “fascia” meaning band or stripe, in reference to the dark lateral body stripe of this species. Both names are adjectives.

MCP

Pontificia Universidade Catolica do Rio Grande do Sul

R

Departamento de Geologia, Universidad de Chile

V

Royal British Columbia Museum - Herbarium

Darwin Core Archive (for parent article) View in SIBiLS Plain XML RDF