Persistence of Stomatepia mongo, an Endemic Cichlid Fish of the Barombi Mbo Crater Lake, Southwestern Cameroon, with Notes on Its Life History and Behavior

Headnote

The extinction of Stomatepia mongo Trewavas, 1972, a cichlid species from the Barombi Mbo crater lake, Cameroon, has been repeatedly speculated. Here, we review over 180 presumably unpublished records of this species since its description. Because a majority of them originate from our extensive surveys in the last several years, it is evident that this species still persists. Nevertheless, it is still considered as the rarest species in the lake, but its relative abundance is probably comparable to that in 1972 when the species was originally described. The species also does not seem to live exclusively in deep waters as was previously hypothesized, because we repeatedly collected and/or observed it in the shallow waters as well. We also listed our notes on the species' coloration and behavior. Although we document the persistence of S. mongo, it remains threatened by the impact of intensive human activities (fishing and farming) in the area.

ALONG the Cameroon Volcanic Line in western Cameroon, numerous crater lakes were formed (Kling, 1988). The Barombi Mbo lake, 1 km NW from Kumba, southwest Cameroon, is the largest (2.5 km in diameter, over 110 m deep, Comen et al., 1992). Due to its relatively easy accessibility, the lake ichthyofauna was repeatedly studied (e.g., Trewavas, 1962; Trewavas et al., 1972; Green et al., 1973; Dominey and Snyder, 1988; Bilong Bilong et al., 1991; Schliewen et al., 1994; Schliewen and Klee, 2004; Martin, 2012), which makes it the best known crater lake in the region.

The species flock of the lake comprises 11 morphologically distinct endemic cichlid species, (but see Martin, 2012), which supposedly evolved via sympatric ecological spéciation from a single common ancestor, which colonized the lake around one million years ago (Schliewen and Klee, 2004; Friedman et al., 2013). Three species from the Barombi Mbo lake are known since the first half of the 20th century, the others were described later (Trewavas, 1962; Trewavas et al., 1972). All the Barombi Mbo cichlid species represent one monophyletic lineage of oreochromine cichlids closely related to Sarotherodon galilaeus distributed in the rivers and streams of the surrounding region (Schliewen et al., 1994). The species flock consists of five genera, four of which are endemic to the lake (i.e., Konia, Myaka, Pungu, Stomatepia-, Trewavas et al.,...