Spectrolebias brousseaui Nielsen, 2013
photo by Vermeulen, F.

Family:  Rivulidae (Rivulines)
Max. size:  3.2 cm SL (male/unsexed); 3.46 cm SL (female)
Environment:  pelagic; depth range 0 - 1 m
Distribution:  South America: Bolivia.
Diagnosis:  This species differs from its congeners by having a unique color pattern of males: anterior third of body light brown, posterior two-thirds of body dark blue, almost black dorsal region, with rows of bright blue spots, relatively large size, with about half the diameter of the pupil. It differs from all its congeners, except S. filamentosus, by having pelvic-fin bases separated by an interspaced (vs. pelvic-fin bases in contact), tip of dorsal and anal fins in males with long filamentous rays (vs. absence of filaments, or presents only on dorsal fin in S. semiocellatus and S. inaequipinnatus, or presents only on anal fin in S. chacoensis), and presence (vs. absence) of contact organs on scales of flank in males (Ref. 93219). Description: Males of S. brousseaui differs from S. filamentosus in color pattern (the latter has an overall reddish color pattern with white spots); having urogenital papillae developed in males and females (vs. poorly developed), and by the longer dorsal-fin base 33.8-36.2% SL (vs. 29.0-31.1%), longer head 27.5-28.8% SL (vs. 25.8-26.7%), lower head 88.6-91.4% HL (vs. 96.2-107.6% ), narrower head 55.6-54.6% SL (vs. 63.4-70.7%), greater number of dorsal-fin rays, 21-22 (vs.16-19), and fewer scales in transverse series 8-9 (vs. 11-12). Females of S. brousseaui differs from that of S. filamentosus by having lower body, 30.6-33.3% SL (vs. 34.7-36.8%); lower caudal peduncle, 11.9-12.6% SL (vs. 13.0-15.0%); shorter anal-fin base 21.9-27.8% SL (vs. 28.8-31.4%); longer head 29.2-30.6% HL (vs. 27.3-28.7%); lower head 78.1-91.6% HL (vs. 93.4-107.2%); smaller head width, 53.0-59.6% HL (vs. 62.7-64.6%); smaller eye diameter, 29.5-32.3% SL (vs. 33.6-34.9%); fewer scales in the longitudinal series of scales, 23-24 (vs. 27-29); fewer scales in the transverse series of scales, 10 (vs. 12) (Ref. 93219).
Biology:  The locality where the species occurs lies at the plateau area (316 m.a.s.l.), just southwest of Llanos de Mojos, which occupy much of the río Mamoré basin. Water temperature at the surface of the pool was 31ºC, at 1 meter depth was 22ºC, and at the marginal area of the pool, at 15 cm depth, was 35ºC. Only small specimens of Trigonectes sp. were collected syntopically in marginal areas, while specimens of Simpsonichthys brousseaui were collected in the deepest areas, at about 1 m deep. The pool has dark water, pH 6.8 and water hardness 80 ppm (Ref. 93219).
IUCN Red List Status: Data deficient (DD); Date assessed: 22 April 2014 Ref. (120744)
Threat to humans:  harmless
Country info:   

Entered by: Capuli, Estelita Emily - 16.08.13

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