Acestrocephalus maculosus, 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 : 390-392

publication ID 10.1590/S1679-62252006000400002

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Acestrocephalus maculosus


Acestrocephalus boehlkei Menezes, 1977 View in CoL Fig. 9 View Fig

Acestrocephalus boehlkei Menezes, 1977: 186 View in CoL , fig. 1 (original description, type locality: Río Punino , tributary of Río Payamino (Napo River system), above Coca, Ecuador).

Material examined. MCZ 51473, holotype, 135 mm SL (radiograph examined), Ecuador: Río Punino, tributary of Río Payamino, Río Napo system, by T. Roberts and Parker, 25-27 November 1971 ; MZUSP 12993-94 View Materials , 2 View Materials , paratypes 85-116 mm SL, taken with holotype ; MZUSP 12995 View Materials , 1 paratype, 40 mm SL, Río Payamino and tributary 3-4 miles upriver from mouth of Río Payamino into Coca , by T. Roberts, Garcia, Parker and Herrera , 20 November 1971 ; MZUSP 38699 View Materials , 2 View Materials , 76-87.5 mm SL, Napo: Río Aguarico in Quarumo, Río Napo system, 0º1’S, 76º37.5’W GoogleMaps . MZUSP 12996- 98 View Materials , 3 View Materials , paratypes, 59-85 mm SL, Peru, Huanuco: backwater near Pueblo Novo flowing into Río Tulumayo, by Catherwood Expedition , 27 September 1955 .

Diagnosis. Acestrocephalus boehlkei , A. maculosus sp.n. and A stigmatus sp.n. are the only species of the genus bearing a dark spot at the humeral region ( Figs. 9 View Fig , 10 View Fig , and 11). Acestrocephalus boehlkei , however, has more anal-fin rays (34-36) than A. maculosus (25-27) and A. stigmatus (29-31) and more scale rows around caudal peduncle (25) than A. maculosus (23) and A. stigmatus (22-23). See tables 4 and 5. Additionally, A. boehlkei differs at once from A. maculosus and A. stigmatus in number of perforated lateral line scales (74-78 vs 70-73 in A. stigmatus and 71-73 in A. maculosus ) and in number of small conical teeth between anterior and posterior canines of outer row premaxillary teeth(10-12 vs 7-9 in both A. stigmatus and A. maculosus (see Tables 6 and 7). The muscular hiatus of the pseudotympanum in A. boehlkei ( Fig. 5b View Fig ) is also wider than those of A. maculosus ( Fig. 5c View Fig ) and A. stigmatus ( Fig. 5d View Fig ).

Description. Morphometrics of holotype and additional specimens presented in table 8. Meristic and morphometric data based on all examined lots of this species because no statistical differences found among them. Body moderately large (SL=31.5-135.0 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=21, including holotype. Posterior most ray unbranched, n =21. Adipose fin present. Anal-fin rays v,34 (iv or v, usually v unbranched, branched rays mean=34.5, range 33-36, n=21, posterior ray split to its base and counted as 1). Slightly developed anterior anal-fin lobe including anterior unbranched rays and first 9-10 branched rays. Anal fin of three sexually mature males with bilateral hooks on posterior part of anterior branched rays. In a specimen 87.5 mm SL (MZUSP 38699) hooks present on anterior 11 branched rays and number of hooks per ray vary considerably: first branched ray with 9, third with 17, sixth with 24 and eleventh with 8. Pectoral-fin rays i,14 (anterior branched ray i in all specimens, n=21), branched rays mean 14.6, range13-16, n=21. Posterior tips of longest pectoral-fin rays reaching beyond pelvic-fin origin. Pelvic-fin rays i,7, n=21. No hooks on pelvic-fin rays of sexually mature males. Distal tips of longest pelvic-fin rays extending to or slightly beyond posterior border of anus, but not reaching anal-fin origin. Principal caudal-fin ray count 10/9, n=21.

Lateral line complete, perforated scales 74 (mean=76.1, range 74-79, n=21). Scale rows above lateral line 13 (mean=13.5, range 13-15, n=21). Scale rows below lateral line 12 (mean=12.1, range 12-13, n=21). Scale rows around caudal peduncle 25 in all specimens, n=9.

Shape, size and arrangement of teeth on premaxilla, maxilla and dentary as in A. sardina . Outer row small conical teeth on premaxilla 12 (mean=10.1, range 9-12, n=21. Maxillary teeth 44 (mean=37.6, range 32-44, n=21), increasing in number according to increase in standard length ( Fig. 6 View Fig ). Posterior row dentary teeth 33 (mean=26.3, range 20-33, n=21), increasing in number ontogenetically ( Fig.7). Inner row dentary teeth 11 (mean=12, range 10-14, n=21).

Vertebrae 39 (mean=39.6, range 39-41, n=9). Total number of gill-rakers on first gill-arch 6 (mean=6.1, range 6-8, n=21).

Arrangement of muscles limiting muscular hiatus of pseudotympanum and degree of exposition of first and second pleural ribs as in A. sardina (compare figs. 5a and 5b).

Color in alcohol. Body light brown to pale yellowish, darker dorsally. Dorsal head and snout more densely pigmented with dark chromatophores compared to lateral part of head. Lateral body stripe broader from below dorsal-fin origin to below adipose-fin origin, narrower from dorsal-fin origin anteriorly to upper opercle and on caudal peduncle, dark color sometimes obscured by guanine. Lateral stripe starts from behind upper opercle extending posteriorly to caudal-fin base where connecting to oblong dark blotch posteriorly extending to middle caudal-fin rays. Irregularly shaped, vertically elongated dark blotch at humeral region over anterior lateral body stripe, vertically above anterior pectoral fin. Mental area of lower jaw with diffuse dark blotch, sometimes unconspicuous or even absent. Small black dot at origin of dorsal-fin origin, extending to first unbranched dorsal-fin ray base. Dorsal, anal, and caudal fin dusky with scattered dark chromatophores along fin rays and membranes. Pectoral and pelvic fins pale with fewer dark chromatophores than other fins.

Distribution. Upper Amazon River basin in tributaries of Río Napo, Ecuador and of Río Putumayo, Peru ( Fig. 8 View Fig ).

Remarks. Lasso & Taphorn (1992) reported A. boehlkei from the Ventuari River, Apure River system, in the upper Río Orinoco, but emphasized that the record should be confirmed. Lasso et al. (2004), in referring to this record added that the specimens probably belong to A. ginesi Lasso & Taphorn (= A. sardina ) or to a species not yet described. Lasso & Taphorn (2000) compared meristic data with specimens from the Río Ventuari to data taken from specimens of A. ginesi (= A. sardina ) and suggested that the former have more branched anal-fin rays and lateral-line scales than the latter (35-38 vs 29-36 and 73-76 vs 63-71 respectively). In two specimens (MZUSP 37268) from the Río Suripa, a tributary of Río Apure, Barinas, Venezuela, the number of anal-fin rays (36 and 37) and maxillary teeth (35 and 38) are outside the range of values for A. sardina (28-33 and 40-53 respectively) and differ from A. boehlkei by having more posterior dentary teeth (32 and 34 vs 20-33 in A. boehlkei ) and fewer small conical teeth in the outer row on the premaxilla (8 and 9 vs 9-12 in A. boehlkei ). This strongly suggests that the specimens from the Apure River system in Venezuela, tentatively identified as A. ginesi (= A. sardina ) and A. boehlkei probably belong to an undescribed species.


Museum of Comparative Zoology


Tavera, Department of Geology and Geophysics














Acestrocephalus maculosus

Menezes, Naércio A. 2006

Acestrocephalus boehlkei

Menezes, N 1977: 186
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