Maratecoara gesmonei Nielsen, Martins & Britzke, 2014

Family:  Rivulidae (Rivulines), subfamily: Rivulinae
Max. size:  2.34 cm SL (male/unsexed); 2.45 cm SL (female)
Environment:  benthopelagic; freshwater,
Distribution:  South America: Brazil, Pará state, São Félix do Xingu, temporary pool at island in the middle of the rio Xingu (Ref. 95615).
Diagnosis:  Dorsal spines (total): -0; Dorsal soft rays (total): 10-11; Anal spines: -0; Anal soft rays: 14-15; Vertebrae: 25-26. Diagnosis: male body depth 23.7-25.9% SL; caudal peduncle depth, 13.0-15.5% SL; length of dorsal-fin base, 13.5-14.5% SL; length of anal-fin base, 19.7-21.5% SL; caudal-fin length, 34.1-41.4% SL; pelvic-fin length, 12.2-14.8%SL; head depth, 62.5-64.6% HL; head width, 33.8-35.7% HL; pectoral-fin posterior margin reaching vertical between base of the 1st and 2nd anal-fin rays; contact organs absent; anal-fin origin between pleural ribs of 12th and 13th; 24-25 caudal-fin rays; 7 pelvicfin rays; 8 transverse series of scales; 25-26 vertebrae; female body depth 23.9-25.9% SL; caudal peduncle depth, 12.7-12.9% SL; length of dorsal-fin base, 11.3-13.3% SL; length of anal-fin base 15.9-18.1% SL; caudal-fin length 31.9-37.2% SL; pectoral-fin length, 19.1-23.8% SL; head depth 63.0-64.7% HL; head width 35.3-39.7% HL; eye diameter 30.8-33.0% HL (Ref. 95615). Description: largest male examined 23.4 mm SL, largest female examined 24.5 mm SL; dorsal profile slightly concave between head and base of dorsal-fin, slightly convex at caudal peduncle; ventral profile gently convex from lower jaw to end of anal-fin base and nearly straight from latter point to caudal peduncle; body moderately slender; greatest body depth at level of pelvic-fin base; jaws short, prognathous, snout slightly pointed; dorsal fin elongated in males, pointed, rays 7-8 much more elongated than remaining rays, filamentous, tips reaching at least distal margin of caudal fin when adpressed to the body; anal fin pointed in males, rays 7-8 much more elongated than remaining rays, filamentous, tips reaching distal margin of caudal fin when adpressed to body; dorsal and anal fins just slightly pointed in females; caudal-fin lanceolate in males, middle caudal-fin rays filamentous, caudal-fin rounded in females; pectoral-fin elliptical, distal margin reaching vertical between base of 1st and 2nd anal-fin rays in males, between urogenital papilla and anal-fin origin in females; pelvic-fin elliptical, without filaments; tip of each pelvic fin reaching between base of 3rd and 4th anal-fin rays in males, reaching to between base of 1st and 2nd anal-fin rays in females; pelvic-fin bases in close proximity medially; dorsal fin origin on vertical between base of 3rd and 5th anal-fin rays, and between neural spines of 11th and 12th vertebrae in males and 13th and 14tth in females; anal-fin origin between pleural ribs of 12th and 13th vertebrae; caudal-fin rays 24-25; scales cycloid; no scales on caudal, dorsal and anal-fins bases; frontal squamation F-patterned; E-scales not overlapping medially; scales arranged in regular transverse pattern; longitudinal series of scales 25-26; transverse series of scales 8; contact organs absent; cephalic neuromasts: supraorbital 6+3, parietal 3, anterior rostral 1, posterior rostral 1, infraorbital 1 + 25, preorbital 4, otic 1, post-otic 2, supratemporal 1, median opercular 1, ventral opercular 1, preopercular 14, mandibular 8, lateral mandibular 5; two neuromasts on fin base (Ref. 95615). Coloration: In life: males: sides of body metallic blue and orange with irregular color distribution, without bars or lines, dorsally orange; abdominal region clear; sides of head metallic blue and orange; jaws orange; iris bright green; a black bar vertically crossing the eye; dorsal-fin orange with metallic blue blotches; anal-fin metallic blue with slightly orange stains; caudal-fin orange with metallic blue spots; pectoral-fins hyaline; pelvic-fins metallic blue with an orange spot (Ref. 95615). Females with overall color light brownish gray, with longitudinal rows of pale brown dots on the sides of body; abdominal region clear; sides of head and jaws gray, with a pale greenish yellow hue; iris yellow, with a dark gray vertical bar through center of eye; fins hyaline (Ref. 95615).
Biology: 
IUCN Red List Status: Least Concern (LC); Date assessed: 07 November 2018 Ref. (130435)
Threat to humans:  harmless


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