Kryptolebias sepia

biology_ecology

Reproduction - Eggs are 2 mm in diameter and have no major filaments on the cambium membrane, but are covered with an elastic and sticky substance. They are placed one by one between roots at the waters edge, or just above it. Under aquarium conditions, K. sepia deposits more than 50 % of its eggs above the waterline. This behavior is occasionally observed in rivuline species of the genus Rivulus (FBMV pers. obs.). Very low water levels stimulate this species to mate, with males aggressively driving females. Decreasing water level to less than 3 cm instantly result in spawning activity. Color of eggs is dark amber matching the color of the spawning substrate. No differences in egg development time were observed under the three incubation conditions. In fully aquatic environment, eggs develop and hatch in 14 to 16 days at 24 ° C. On both wet and moist peat moss, eggs develop normally within the 14 to 16 day period, but do not hatch. If not allowed to hatch by immersing them in water, the embryos die within the following next seven days. This species is therefore unlikely to lay eggs capable of undergoing a developmental diapause (Wourms 1972), and the three week period potentially s

Kryptolebias sepia n. sp. (Actinopterygii: Cyprinodontiformes: Rivulidae), a new killifish from the Tapanahony River drainage in southeast Surinam.

description

Description - A medium sized Kryptolebias, robust shape, with a non-annual lifecycle. Morphometric data of holotype, allotype and eight paratypes from different localities are given in Table 2 in millimeters and in Table 3 as percent of standard length. Meristic data are in Table 4. Males differ little from females in their body coloration, shape and fins. In adult males yellow marking on the gill cover is slightly more prominent and some but not all males show a few yellow markings along the lateral line. Frontal scalation pattern is in general E-type, but one individual showed mixed E-D-type (Hoedeman 1958). The strong melanism observed in K. sepia is also observed in at least three other species of Kryptolebias - K. caudomarginatus, K. brasiliensis and K. marmoratus - and in R. atratus. However, K. sepia is differentiated from these species by morphometric data, lower dorsal fin ray count (7.8 vs. 8.6 to 9.0), high anal fin ray count (15.1 vs. 11.2 to 12.6), by the absence of clear sexual dimorphism, by a network of dark markings beginning behind the eye and continuing just posterior of gill cover, by an oblique pattern on the lateral sides, and by their extraordinary capability

Kryptolebias sepia n. sp. (Actinopterygii: Cyprinodontiformes: Rivulidae), a new killifish from the Tapanahony River drainage in southeast Surinam.

diagnosis

Diagnosis - Distinguished from other Kryptolebias and Rivulus species by a combination of characters including low number of LL scales, high number of anal rays, short predorsal length and a robust body (Table 1), and unique mitochondrial DNA gene sequences. Kryptolebias sepia is further distinguished by remarkably strong melanistic pigmentation and the ability to change this coloration into several distinct patterns, lack of obvious sexual dimorphism, strong dichromatism between juveniles and adults, and absence of the “ Rivulus ” spot in females and juveniles.

Kryptolebias sepia n. sp. (Actinopterygii: Cyprinodontiformes: Rivulidae), a new killifish from the Tapanahony River drainage in southeast Surinam.

discussion

Phylogenetic relationships - The maximum likelihood and the Bayesian likelihood analysis yielded identical topologies. Due to the size of the data set, it was not practical to estimate nodal support of the maximum likelihood topology via bootstrapping. Therefore, we report the maximum likelihood topology, conveying information on branch lengths, and indicate support for individual nodes with Bayesian posterior probability values (Fig. 9). Kryptolebias sepia shows a statistically well supported sister taxon relationship to K. brasiliensis (Figs. 9, 10). The monophyly of Kryptolebias whose members in addition to K. sepia are K. marmoratus, K. caudomarginatus, and K. brasiliensis, is also strongly supported (Figs. 9, 10). These relationships are recovered in all analyses, and strongly support the hypothesis that K. sepia is indeed a phylogenetic member of the genus Kryptolebias. Costa (2004 b) also placed R. campelloi into Kryptolebias, although this species was not included in the analysis on which this taxonomic revision was based; it was reassigned without being listed as examined. The maximum parsimony topology (Fig. 10) suggests that Kryptolebias is sister to all other Rivulidae

Kryptolebias sepia n. sp. (Actinopterygii: Cyprinodontiformes: Rivulidae), a new killifish from the Tapanahony River drainage in southeast Surinam.