KILLI - DATA SERIES, 2023, Huber, Mejia & Vermeulen, (re)descriptions Rivulus, Colombia

Killi-Data Series 2023 [116 pages, as a print, ISBN 978-2-9547546-4-2, as a PDF document, ISBN 978-2-9547546-5-9]

Killi-Data Series 2023, 74-100, 14 figs.

Two new Rivulus sp. from north-western Colombia, after a redescription of Riv. pacificus (Cyprinodontiformes, Rivulidae).

Jean H. Huber, D.A. Mejía-Vargas & F.B.M. Vermeulen. 

Abstract : Following new collections in coastal and inland north-western Colombia, Rivulus pacificus Huber, 1992, is redescribed based on live nearby topotypes, then redefined in a restricted sense, and two new cryptic congeners, also from the Colombia lowlands, are described as Rivulus gomesi n. sp., and Rivulus paradiseus n. sp., both from the north-western lowlands, in the Atrato river system, near Chigorodó, Antioquia for the former and in the Acandí river basin, facing the Caribbean coast near Acandí, close to the Panama border, for the latter. The three species form a group of closely related species, not morphologically related and not pattern-wise related to the elegans species group, dominant in the Northern Colombian Andes and inter-Andean valleys and vicariant. Instead, they are morphologically more related to the micropus species group with a huge distribution in northern and north-eastern South America. The three species are not separable by morpho-meristics but are diagnosed by a combination of pattern characters in male and female. R. gomesi is mainly separated from the similarly-morphed pacificus by the presence of a supracaudal ocellus in females and by body pattern (red lines faint and irregular vs. fully lineated in pacificus males) ; R. paradiseus mainly differs from R. gomesi, also with a supracaudal ocellus in female (unlike pacificus, missing one), by body pattern (5 to 6 evenly interrupted red lines vs. irregularly scattered red lines and by posterior Anal fin and basal Caudal fin with reticulated inner (green spots, not red) pattern vs. few red dots. R. gomesi and R. paradiseus do fit well into the micropus group according to latest evidence. On the contrary, the elegans species group differs in Colombia from all members of the micropus group by having a more forward set Dorsal fin relative to the Anal fin; truncated Caudal fin vs. rounded; a larger maximum size (up to 90 mm TL vs. 63 mm TL on average. The 3 species of the R. pacificus group are separated notably from vicariant R. elegans and its 3 allied (chucunaque, sucubti, that taxon being formally proposed as a junior synonym of chucunaque, and leucurus) by live pattern and morphology. Hypotheses to explain the present distribution are forwarded.

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