Scientists from the USA, Japan and South Africa have described a new species of Lepidiolamprologus from Lake Tanganyika that practices aggressive mimicry.
The new species, named Lepidiolamprologus mimicus, is known from the Zambian (southern) coast of Lake Tanganyika, and is described in a paper in a recent issue of the journal Zootaxa by Robert Schelly, Tetsumi Takahashi, Roger Bills and Michio Hori.
Lepidiolamprologus mimicus can be distinguished from other members of the genus in having by its unique colour pattern of bright yellow fins and a brownish-tan flank with large dark brown spots along it.
Additionally, it is distinguished by the possession of a semsamoid bone in the labial ligament, 2 pores at neurocranial lateral line foramen 0, body depth 23.4"26.2 % SL, head length 31.0"33.7 % SL, interorbital width 17.4"24.5 % HL, 11 dorsal-fin rays, 73"79 longitudinal scales, 10"12 gill rakers on the first arch, 34 vertebrae, and a colour pattern based on three rows of irregular spots.
According to the authors: Underwater observation during the period and analysis of stomach contents of samples revealed that this species was exclusively piscivorous and mainly preyed on young and sub-adults of cyprichromine cichlids.
In the littoral region of Kasenga, four species of cyprichromine (Cyprichromis leptosoma, C. zonatus, C. coloratus, and Paracyprichromis brieni) form mixed-species schools composed of various subgroups of age or sex of each species in open water 1"4 m above the rocky substrate...
Usually L. mimicus n. sp. stalked solitarily near or mingled in the school at a depth of 10 m or more, and attacked mainly young and juveniles of the school. At least 30"40 individual hunts were observed.
When hunting, adults of L. mimicus n. sp. changed their body coloration markedly from dark-brown to pale beige; their characteristic dark-brown spots disappeared and rows of fine silver dots on the flank faded, but the yellow anal fin and black dotted line at the tip of the dorsal fin remained. This colouration generally looked like that of female cyprichromines and specifically very much resembled that of female Paracyprichromis brieni.
The degree of resemblance in colouration of L. mimicus n. sp. to its prey during hunting was greater in young and sub-adults than adults...and the predominant prey were young and juveniles of Paracyprichromis brieni, with small Cyprichromis making up the balance. These phenomena indicate both that L. mimicus n. sp. is highly specialized to forage on cyprichromine fishes and also that its colouration, especially during hunting, is a form of aggressive mimicry.
For more information, see the paper: Schelly, R, T Takahashi, R Bills & M Hori (2007). The first case of aggressive mimicry among lamprologines in a new species of Lepidiolamprologus (Perciformes: Cichlidae) from Lake Tanganyika. Zootaxa 1638, pp. 39"49.