The seven species of small-sized fish species that coexisted in the nine ponds included in this study were: Astyanax altiparanae (Garutti; Britski, 2000) (28-106 mm SL); Astyanax jasciatus (Cuvier, 1819) (38-76 mm SL); Bryconamericus stramineus Eigenmann 1908 (18-45 mm SL); Hemigrammus
marginatus Ellis, 1911 (23-49 mm SL); Hyphessobrycon eques (Steindachner, 1882) (12-34 mm SL); Moenkhausia intermedia Eigenmann, 1908 (19-68 mm SL) and Moenkhausia sanctaefilomenae (Steindachner, 1907) (14-46 mm SL).
The photos show two males with the longest dorsal rays dark and prolonged, probably reaching adipose if depressed, a probably vertical humeral spot followed by a light zone, and a caudal spot beginning above the last fourth of the anal fin and continuing on the lower part of the peduncle then onto the middle of the fin up to the tip of the middle caudal fin rays, with a light spot on the upper part of the peduncle and on the base of the lobes, a pattern ressembling that of Hemigrammus hyanuag or Hemigrammus haraLA for example.
25 in SL, resembling Hemigrammus levis without humeral spot (or feebly pronounced in vivo) and a large caudal spot on the centre of the fin, surrounded by conspicuous white bands; anal fin short, its base surmounted by a black line on its anterior half.
Lowe McConnell collection in the Serra de Roncador, this photo may represent a new form (represented in her collection by two specimens, from Corrego do Gato, Rio Xingti drainage, Hemigrammus Roncador U3).
A new species of Hemigrammus
from the upper rio Negro basin, Brazil, with comments on the presence and arrangement of anal-fin hooks in Hemigrammus
and related genera (Ostariophysi: Characiformes: Characidae).
The genus Hemigrammus Gill, 1858 is one of the most speciose genera within the family Characidae, with 50 species currently recognized as valid (Lima et al.
The new Hemigrammus species presented herein was collected in the course of an ongoing survey of the fish diversity in the middle and lower portions of the rio Tiquie basin.
Gery (1965: 19) noticed the presence of "1-2 fort crochets sur les premiers rayons ramifies chez le male" in Hemigrammus ocellifer (Steindachner, 1882).
The conclusion that anal-fin hook arrangements and morphology in Hemigrammus constituted a hardly exploited source of morphological information, generally neglected in standard phylogenetical studies of characids due to the relative scarcity of mature material bearing these structures, prompted us to conduct a preliminary survey of the variability of this character.
Diagnosis: Hemigrammus yinyang can be distinguished from all congeners by the presence (in life specimens) of an orange blotch, situated between two dark humeral blotches, immediately ahead and slightly above the posterior, darker second humeral blotch.
Geographical distribution: Hemigrammus yinyang is only known from tributaries of the middle rio Tiquie, a tributary of the rio Uaupes, upper rio Negro basin, Amazonas state, Brazil (Fig.
Ecological notes: Hemigrammus yinyang was collected in moderately large (2-6 m wide) streams, tributaries of rio Tiquie and including igarape Castanha, the largest tributary of rio Tiquie at its central course.