Revision of the African cichlid fish genus Ctenochromis (Teleostei, Cichliformes), including a description of the new genus Shuja from Lake Tanganyika and the new species Ctenochromis scatebra from northern Tanzania

Abstract

Molecular phylogenetic evidence clearly resolves the African cichlid fish genus Ctenochromis, as defined by Greenwood (1979), as paraphyletic. Here, we redefine the genus Ctenochromis and assign Ctenochromis horei, a member of the Tropheini from Lake Tanganyika, to a new genus Shuja gen. nov. We restrict Ctenochromis to Ctenochromis pectoralis and Ctenochromis scatebra sp. nov., both of which are endemic to the Pangani River catchment in northern Tanzania, and are resolved as sister taxa in a phylogenetic analysis using genome-wide data. Ctenochromis pectoralis is the type species of the genus and described from specimens collected near Korogwe, Tanzania. The species was declared extinct in a 2016 IUCN Red List Assessment. We confirm the continued presence of a population of C. pectoralis within the Ruvu tributary linking Lake Jipe to Nyumba ya Mungu Reservoir. The new taxon Ctenochromis scatebra sp. nov. is described from Chemka Springs, and recognised on the basis of differences from C. pectoralis in tooth and jaw morphology.

Revision of the cichlid fish genus Gnathochromis (Teleostei: Cichlidae) from Lake Tanganyika with the description of a new genus Jabarichromis gen. nov.

“…A revision or specification of this definition is needed because all our specimens show additional scales with small ctenii along the midbody, increasing in numbers towards the ventral and posterior side. This state for Jabarichromis gen. nov. pfefferi was also reported by Genner et al (2022). Further, ctenoid scales along the midbody for species belonging to the Tropheini were reported by Viertler et al (2021).…”

“…To evaluate possible diagnostic characters to distinguish Shuja from Ctenochromis, we further inspected specimens from all species that are associated with Ctenochromis (i.e., Ctenochromis pectoralis Pfeffer 1893), or were formerly associated with Ctenochromis before the recent revision by Genner et al (2022): Haplochromis bakongo (Thys van den Audenaerde 1964), Haplochromis demeusii (Boulenger 1899), Haplochromis fasciatus (Perugia 1892), Haplochromis luluae (Fowler 1930), Haplochromis oligacanthus Regan 1922, Haplochromis polli Thys van den Audenaerde 1964. In addition to these riverine Haplochromines, we also inspected specimens of the species Trematochromis benthicola (Matthes 1962), formally 'Ctenochromis' benthicola, which is endemic to Lake Tanganyika and is a member of the Cyphotilapiini (Muschick et al 2012).…”

“…Included species. Jabarichromis pfefferi (Boulenger 1898) Paratilapia pfefferi Boulenger, 1898 Limnochromis pfefferi (Boulenger), Regan, 1920 Haplochromis pfefferi (Boulenger), Poll, 1974 Gnathochromis pfefferi (Boulenger), Poll, 1981 Additional diagnostic characters for Shuja horei Genner et al (2022) erected the genus Shuja for S. horei to separate it from Ctenochromis and the other Tropheini. They pointed out the uniqueness of a prognathous lower jaw in S. horei compared to the other Tropheini with either a retrognathous or isognathous lower jaw.…”

“…Alongside 'G.' pfefferi, also its sister species Shuja horei (Genner et al 2022) was reallocated from the Haplochromini to the Tropheini by (Takahashi 2003). Note that Shuja horei underwent a generic revision only recently and that the genus to which it was previously allocated to (Ctenochromis) used to be polyphyletic with several species from different drainages and phylogenetic lineages associated to it (including the Lake Tanganyika Cyphotilapiini; Genner et al 2022).…”

Turnover of sex chromosomes in the Lake Tanganyika cichlid tribe Tropheini (Teleostei: Cichlidae)

“…We obtained new sequencing data from pooled males and females from four species collected in 2019 near Kalambo Lodge, Zambia near the southern end of the lake (-8.623°N, 31.200°E): 25 males and 23 females of Pseudosimochromis babaulti, 23 males and 25 females of Gnathochromis pfefferi , 24 males and 21 females of Interochromis loocki , and 25 males and 25 females of Shuja horei ( Ctenochromis horei ) 50 . We also analyzed a full-sib family of 30 males and 28 females of Simochromis diagramma reared at U. Graz.…”