Heroina isonycterina Kullander

Synonymy

Heroina isonycterina Kullander, 1996. Ichthyol. Explor. Freshwaters 7, p. 153 (Ecuador, Provincia Napo, Río Napo drainage, upper Río Tiputini upstream of bridge on road to Coca (0º44.5'S 76º53'W)).

Heroina isonycterina, paratype, FMNH 96562, 83.3 mm SL, adult female in probable breeding colour pattern from the Río Tiputini drainage, Ecuador. Photo: S.O. Kullander.

Diagnosis

Only species of Heroina, H. isonycterina can be recognized by characters in the generic diagnosis. The following external characters may otherwise be helpful (from Kullander, 1996, modified).

Deep bodied, strongly compressed laterally. Lower lip fold continuous across symphysis. Scales in E1 row 27-29, usually 28. Dorsal and anal fins with wide basal scale cover. Dorsal fin count XVI-XVII.12-13; soft dorsal fin pointed, rays 5-6 slightly prolonged, extending to 4/5 or beyond end of caudal fin, shorter in females. Anal fin count VII.10-11; soft anal fin pointed, to 4/5 to end of caudal fin, not produced, 6th soft ray longest.

Oral teeth all caniniform. Dentigerous arm of premaxilla toothed for about half its length; outer row teeth increasing in size symphysiad, symphysial 1+1 teeth longest, not tightly juxtaposed; distinct gap separating outer row teeth from inner rows; inner teeth much smaller than outer teeth. Dentary toothed along most of rim anterior to coronoid process; outer row teeth increasing in size symphysiad but symphysial 1+1 teeth reduced in size, the next 1+1, 2+2 or 3+3 teeth distinctly longer than the rest; no distinct gap separating outer and inner rows; inner teeth much smaller than outer teeth. Gill rakers externally on first gill arch, 1, rarely 2 epibranchial; 1 in angle; 6-8 ceratobranchial. Microbranchiospines absent from all gill arches. Vertebrae 12+17 or 13+16-17, totalling 29-30.

Preserved specimens with 8-9 brown or grey vertical bars, a rounded or vertically slightly ovate midlateral spot, a prominent round or square dark brown caudal base spot, and a variably expressed pattern of minute spots scattered over most of the sides and fins. Anal fin always darker than the other unpaired fins; brown to dark brown, lighter toward tip of soft portion. Spinous dorsal fin brown, soft portion brown basally, gradually lighter toward tip of soft portion. Caudal fin dusky. The soft dorsal fin and caudal fin usually display small dark dots, but sometimes those fins are immaculate. Breeding female specimen, 83.3 mm (FMNH 96562), shown in the photo, displays portions of vertical bars deep brown instead of rather indistinct and uniform.

Peruvian specimens photographed alive in the field are pale greyish with dark grey vertical bars, and narrow grey horizontal lines running along scale overlaps, or dark grey with blackish vertical bars. Aquarium specimens in neutral colour are pale olivaceous with grey vertical bars and black midlateral and caudal spots, and horizontal rows of red spots on anterior sides. Bars and spots can fade away, however. The iris is red. The anal fin with distal border iridescent green. Spots in the dorsal, anal and caudal fin are red; interspaces iridescent green in the dorsal and caudal fin. A narrow red margin to dorsal fin lappets and soft dorsal fin upper margin.

Heroina isonycterina. Young adult male collected at Aguas Calientes, Colombia, photographed in aquarium. Photo: U. Werner.

Breeding specimens specimens observed by Werner (1996) in aquarium took on an emphasized barred colouration and eyes turned deep red. While guarding eggs particularly the female showed much darker vertical bars, and the lower head and chest terned nearly black.

The largest specimen examined is the holotype,109.1 mm SL.

Holotype

FMNH 105181. Male, 101.9 mm SL. Ecuador, Provincia Napo, Rìo Napo drainage, upper Rìo Tiputini upstream of bridge on road to Coca (0º44.5'S, 76º53'W). 3 Nov 1981. Collected by D. J. Stewart, M. Ibarra and R. Barriga, field no. DJS-81-70.

Etymology

The species epithet is an adjective derived from the Greek words isos, equal, and nykterinos, an adjective of night, nyx, and corresponds to the Latin aequinoctialis, of equal nights, referring to the equatorial distribution of the species.

Geographical distribution

Collected in the Napo drainage around Coca in Ecuador, in the Orteguaza in Colombia, and in the Corrientes, Tigre and Pastaza in Peru close to the Ecuadorian border (Kullander, 1996; Werner, 1996).

Natural history

Heroina isonycterina. Collecting locality, Aguas Calientes, Colombia. Photo: U. Werner.

Generally collected in small numbers in small streams with shallow water, usually turbid and with sandy bottom, often in deforested locations. Recorded temperatures range 23-29.4ºC, pH 6.5-7.0, hardness 7-39 ppm. (Kullander, 1996; Werner, 1996.)

Aquarium observations show Heroina isonycterina to be a biparental substrate brooder (Werner, 1966). Werner's specimens were sexually mature at fully 10 cm total length. Preferred egg deposition sites were oblique or vertical areas with cover. Eggs numbered up to 250 and were almost rounded rather than oval and less than 1 mm in diameter.

Local name

Not recorded.

References

KULLANDER, S.O. 1996. Heroina isonycterina, a new genus and species of cichlid fish from Western Amazonia, with comments on cichlasomine systematics. Ichthyol. Explor. Freshwaters, 7: 149-172.
WERNER, U. 1996. Aus Kolumbien mitgebrach: Ein neuer Buntbarsch der Cichlasoma-Verwandtschaft. DATZ 49:634-637.