Acestrocephalus boehlkei

description

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, range 13 - 16, n = 21. Po

Description of five new species of Acestrocephalus Eigenmann and redescription of A. sardina and A. boehlkei (Characiformes: Characidae)

diagnosis

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, 10, 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. 5 b) is also wider than those of A. maculosus (Fig. 5 c) and A. stigmatus (Fig. 5 d).

Description of five new species of Acestrocephalus Eigenmann and redescription of A. sardina and A. boehlkei (Characiformes: Characidae)

discussion

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

Description of five new species of Acestrocephalus Eigenmann and redescription of A. sardina and A. boehlkei (Characiformes: Characidae)

distribution

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

Description of five new species of Acestrocephalus Eigenmann and redescription of A. sardina and A. boehlkei (Characiformes: Characidae)