This species was originally described as Simpsonichthys longignatus.

W. Costa (2006) assigned many members of the genus Simpsonichthys to the subgenus Hypsolebias (Costa 2006). Hypsolebias was subsequently elevated to a genus (Costa 2011). According to some scientists, the separation of Hypsolebias from the genus Simpsonichthys is insufficiently substantiated and, therefore, debatable.

Discoverer(s): Wilson J.E.M. Costa, Claudia P. Bove, May 13. 2008.

Type locality: road CE-040, about 25 km from Fortaleza (southerly), Pacoti river floodplains, municipio de Aquiraz, Ceará state, altitude 25 m, (northeastern) Brasil.

Etymology: distant (from Latin: longus) born (from Latin: gnatus or natus), in reference to the long distance between the type locality of the species and the distribution of related components.

Diagnosis: distinguished from related components by the shape of the female Anal fin (spatula-shaped, elongated vs. short, semi-circular) (Costa, 2008h).

Hypsolebias longignatus is from the Pacoti River basin, an isolated coastal drainage of northeastern Brazil. It is considered to be closely related to three species of the Tocantins River basin, H. multiradiatus, H. flammeus and H. brunoi, by all possessing bright blue anal

fin in males and concave dorsal profile of head. It differs from those three species by having black spots on the anterior part of the dorsal fin and transverse series of small blue spots on the caudal fin in males. It is also distinguished by some features in combination, including numerous dorsal-fin rays in males, absence of long filaments on the dorsal and anal fins, and few neuromasts on supraorbital, infraorbital, preopercular and mandibular series.

This species can be productive, and the fry is small. Immediately after hatching, the fry should be fed with freshly hatched Artemia nauplii (brine shrimp) or better Paramecium. As most annual species do, they spawn by diving entirely into the substrate. It is best to provide a container with a lid on top in which a hole is made to allow the fish access. That container will need to have enough peat in it for the fish to dive completely into it. For most Hypsolebias species, egg development is complete after 8-10 weeks. However, it is wise also to check a few weeks earlier to see if any eggs have fully developed. Do not let the peat dry too far because the Hypsolebias like it moist. The development will be slower at storage temperatures between 21 and 24 Celsius and speed up at 25-29 Celsius. Before watering the eggs, put some eggs in the water of about 18-20 degrees Celsius to see if the eggs hatch

correctly. That usually happens within 2-6 hours. Then, if eggs hatched well and fry, swim correctly, bring all remaining peat in the water. You may need to re-pack the peat after pouring over the first group of fry to a larger tank. With regular water changes and sufficient food, the young will grow quickly, and after about 5-6 weeks, they can already produce their first eggs. Since this genus has an annual life cycle, the expected life span in captivity is not much more than 10 to 12 months. Their life expectancy is limited to when their pool still has water in the wild. This period can vary from 6 to 8 months.

Remarks:

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Max. size 4.0 cm.
Dorsal 24.5,
Anal 24.5,
D/A -2.0
LL scale count (average) 25
Pre- dorsal length to % SL – 44.9 %
Depth to % SL – 37.2 %

Costa W.J.E.M., June 2008. Simpsonichthys longignatus, a new seasonal killifish of the S. flammeus group from the Pacoti River basin, northeastern Brazil (Cyprinodontiformes: Rivulidae). Ichthyol. Explor. Freshwaters, Vol. 19, No. 2, pp. 155-159, 2 figs., 1 tab.

Ponzetto, J.M., R. Britzke, D.T.B. Nielsen, P.P. Parise-Maltempi & A.L. Alves. 2016. Phylogenetic Relationships of Simpsonichthys subgenera (Cyprinodontiformes, Rivulidae), including a Proposal for a new genus. Zoologica Scripta, 45 ( 4) (July 2016): 394-406

Abrantes, Y.G., L.S. Medeiros, A.B.A. Bennemann, D.M. Bento, F.K. Teixeira, C.F. Rezende, T.P.A. Ramos & S.M.Q. Lima. 2020. Geographic Distribution and Conservation of seasonal killifishes (Cyprinodontiformes, Rivulidae) from the Mid-Northeastern Caatinga Ecoregion, northeastern Brazil. Neotropical Biology and Conservation, 15 (3): 301-315.