Odontostilbe weitzmani

description

Description. Morphometric data on Tab. 1. Body elongate and slightly compressed (Fig. 1). Greatest body depth at vertical through dorsal-fin origin. Snout slightly elongated and round. Dorsal profile of head convex from snout to vertical through anterior bony orbital margin, slightly concave from that point to distal tip of supraoccipital bone. Predorsal profile slightly convex from posterior end of supraoccipital to dorsal-fin origin. Dorsal-fin origin located anteriorly at midlength of SL. Body profile in base of dorsal fin straight to slightly convex and slightly convex from there to origin of adipose fin. Body profile between adipose-fin base and first rays of caudal fin slightly concave. Ventral profile of head slightly convex from snout to origin of pelvic fins and slightly convex from there to origin of anal fin. Body profile along base of anal fin straight or slightly convex. Ventral profile of caudal peduncle straight to slightly concave. Caudal peduncle slightly longer than deep. Head small relative to body length, 22.8 - 27.7 % SL. Mouth terminal, and opening below horizontal line through middle of eye pupil. Upper and lower jaws with approximately same length. Maxilla s

Two new species of Odontostilbe historically hidden under O. microcephala (Characiformes: Cheirodontinae)

description

urn: lsid: zoobank. org: act: B 3 D 5 A 4 C 7 - DF 4 C- 482 A- 83 B 9 - 0147 BE 3 C 60 FE

Two new species of Odontostilbe historically hidden under O. microcephala (Characiformes: Cheirodontinae)

diagnosis

Diagnosis. Odontostilbe weitzmani differs from all species of the genus, except from Odontostilbe avanhandava, by the presence of mesopterygoid teeth, grouped on median portion of the bone, forming a continuous row (vs. absent). Odontostilbe weitzmani is distinguished from O. avanhandava by premaxillary teeth with 5 (13) or 7 (3) cusps [usually 5], with central cusp wider and larger than lateral cusps (vs. premaxillary teeth bearing 7 - 11 [usually 9] cusps, all approximately with the same size), and by the presence of 20 - 21 lamellae in left and right sides of central median raphe of olfactory rosette (vs. 11 - 12). Additionally O. weitzmani is distinguished from O. dierythrura, O. euspilurus, and O. microcephala by the terminal mouth (vs. subterminal mouth); from O. pulchra and O. ecuadorensis by the presence of hooks on first to seventh, [mostly fifth to sixth] branched anal-fin rays of males (vs. hooks on first to 22 nd branched anal-fin rays of males in O. pulchra, first to sixteenth in O. ecuadorensis); from O. splendida by the origin of adipose fin positioned at vertical through last anal-fin ray insertion (vs. origin of adipose fin, at vertical through last 2 or 3 anal-fin

Two new species of Odontostilbe historically hidden under O. microcephala (Characiformes: Cheirodontinae)

discussion

Conservation status. Odontostilbe weitzmani is abundant where it occurs. This species may be categorized as Least Concern (LC), according to the IUCN criteria for evaluation on threatening status, version 13 (IUCN, 2017). Remarks. Besides the type specimens from the upper rio Paraná basin, on which we based the description, we analyzed additional lots of Odontostilbe weitzmani from two localities along the rio Corumbá, Goiás (MCP 25999 and MCP 26000 - female, 55.1 - 56.8 mm SL). These specimens have the same number of cusps on premaxillary teeth, number of branched anal-fin rays and other morphometric characters as the type specimens, but can be differentiated in the length of caudal peduncle (9.9 - 11.8 % SL, mean 10.6 % SL vs. 10.8 - 14.5 % SL, mean 12.5 % SL in O. weitzmani type specimens) and body depth at dorsal-fin (35.0 - 37.1 % SL, mean 36.0, vs. 23.1 - 32.9 % SL, mean 27.9 % SL in O. weitzmani type specimens). We suggest that this difference is related to the larger size of the individuals from rio Corumbá. Stretches of the rivers where these specimens were collected have been changed from lotic to lentic environments by the construction of hydroelectric power dams, and th

Two new species of Odontostilbe historically hidden under O. microcephala (Characiformes: Cheirodontinae)