Shuja Genner, Ngatunga & Turner, 2022

Genner, Martin J., Hsu, Ling-Lan, Collins, Rupert A., Smith, Alan M., Saxon, Andrew D., Shechonge, Asilatu H., Ngatunga, Benjamin P. & Turner, George F., 2022, 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, European Journal of Taxonomy 819, pp. 23-54 : 40-41

Genus Shuja Genner, Ngatunga & Turner gen. nov.

urn:lsid:zoobank.org:act:7862EC4A-51D5-4535-98D5-650D6CC165A7

Type species

Chromis horei Günther, 1894 .

Diagnosis

Shuja gen. nov. can be diagnosed as a genus of haplochromine cichlid within the Tropheini . According to Takahashi (2003: 379), the Tropheini have “extensively granulated cycloid scales at midbody”, with the “granulations comprising irregularly arranged, variously shaped protrusions over almost entire exposed surface”. Shuja gen. nov. is the only representative of the Tropheini with a prognathous lower jaw, versus the retrognathus or isognathus jaw in other genera within the Tropheini ( Table 2 ).

Etymology

The genus name is derived from the Swahili noun ‛shujaa’, translated into English as ‛brave person’ or ‛warrior’, referring to the notable territorial behaviour of the males of this genus.

Description

One species in genus Shuja horei gen. et comb. nov. Species description, from original German text ( Günther 1894: 630): “Dorsal fin 14 spines 8 rays, L. lat 28, L. trans. 4/9. Teeth bicuspid, cusps subequal, slightly tinged with brown; 28–31 each side of upper jaw outer series. Cheeks naked or few extremely thin scales. In specimen nearly 5 inches (12.70 cm) long eye diameter nearly equal to depth of soft part of cheek, a little less than width of preorbital and interorbital space, which is flat. Preopercular limbs at right angle. Body height less than length of head, and one third of total (without caudal). Last dorsal spine longest, two fifths of head length. Pectoral fin to, or nearly to, origin of anal fin. Caudal scaleless. Scales rough, some with margins ciliated. Body light greenish, with incomplete brownish cross-bands on upper part of body. Largest specimen cheek and snout with irregular deep brown spots. Soft dorsal and caudal fin with scattered ocelli; milky-white spot between last two anal rays.” In Shuja horei gen. et comb. nov. hypertrophied lips absent.

Remarks

Shuja gen. nov. belongs to Tropheini tribe of African cichlids, originally defined by Poll (1986). The diagnosis of Tropheini is the presence of “extensively granulated cycloid scales at midbody” ( Takahashi 2003: 379). Our observations suggest such granularity of the flank/midbody scales in Tropheini is present in Shuja horei gen. et comb. nov., Gnathochromis pfefferi and Lobochilotes labiata , at least, but also small ctenii are present. These ctenii are sparse and largely restricted on the margins of this caudal edge of

the scale. Viertler et al. (2021) report multiple species in the Tropheini with ctenoid scales on the central flank area. Further detailed work of all described species is needed to determine if the distribution of the granulation and ctenii on midbody scales is diagnostic of the Tropheini . Nevertheless, irrespective of morphological traits, the tribe is unambiguously monophyletic in genome-scale molecular phylogenetic analyses (Ronco et al. 2021), and endemic to Lake Tanganyika and immediate river systems. Within the tribe, Shuja gen. nov. is a monotypic genus and can be distinguished from other representatives of the Tropheini by the presence of a prognathous jaw ( Fig. 5a–c ), when all other described species in the Tropheini have a retrognathus or isognathus jaw ( Table 2 ). These include Gnathochromis pfefferi , and representatives of Interochromis , Limnotilapia , Lobochilotes , Petrochromis , Pseudosimochromis , Simochromis and Tropheus ( Table 2 ).

Figures

Fig. 5. Shuja horei gen. et comb. nov.a. Illustration from the original type specimen (Günther 1894).b. A freshly caught specimen collected in 2016 from the Malagarasi River, Ilagala (BMNH 2021.7.15.14). c. Radiographs of the type series (syntypes) from the Natural History Museum (BMNH 1889.1.30.13– 15). Note the prognathous jaw that distinguishes Shuja Genner, Ngatunga & Turner gen. nov. from other genera within the Tropheini Poll, 1986. Radiographs from the Natural History Museum, London (Creative Commons Attribution License (CC BY 4.0)). Scale bars: 10 mm.