Chindongo, Li, Shan, Konings, Adrianus F. & Stauffer, Jay R., 2016

Li, Shan, Konings, Adrianus F. & Stauffer, Jay R., 2016, A Revision of the Pseudotropheus elongatus species group (Teleostei: Cichlidae) With Description of a New Genus and Seven New Species, Zootaxa 4168 (2), pp. 353-381 : 372-373

Chindongo gen. nov.

Pseudotropheus elongatus was described from specimens collected in Mbamba Bay , Tanzania ( Fryer 1956). Most members of the P. elongatus species group are small species with a standard length less than 10 cm ( Ribbink et al. 1983). Members of this complex which are morphologically distinct from Metriaclima , Tropheops , Cynotilapia , or from the type species of Pseudotropheus , P. williamsi , will be placed into the newly defined genus.

Type species. Chingongo bellicosus sp. nov.

Diagnosis. This genus is comprised of small, rock-dwelling haplochromine cichlids endemic to Lake Malaŵi. The possession of the following characteristics aligns Chindongo with the other 13 mbuna genera in Lake Malaŵi: 1) large number of small scales on the nape and chest region; 2) abrupt transition from large flank scales to small chest scales; 3) reduction of the left ovary; and 4) possession of true ocelli ( Fryer, 1959). The following morphological characteristics distinguish Chindongo : 1) the presence of bicuspid teeth in the anterior portion of the outer row of both upper and lower jaws; 2) a moderately to steeply sloped vomer with a narrow rostral tip making an angle of between 53° and 68° with the parasphenoid; 3) small mouth with lower jaw slightly shorter than upper; 4) broad anterior dentigerous area on both premaxilla and dentary with 3 or more rows of teeth (usually 5–6 rows); 5) a flank melanin pattern consisting of vertical bars without horizontal elements at any stage of development.

Chindongo is distinguished from Abactochromis , Cynotilapia , Gephyrochromis , and some Labidochromis by the presence of bicuspid teeth in the anterior portion of the outer row of both the upper and lower jaws, which are unicuspid in the other genera, and from Petrotilapia and Labeotropheus as representatives of these two genera have tricuspid teeth. Chindongo is further distinguished from Labidochromis by the absence of an inclination of the anterior dentigerous area of the dentary which makes an angle of 30–45° with the dentigerous arms in Labidochromis (in Chindongo the anterior and posterior dentigerous areas of the dentary are in about the same plane as the arms), and by a wide U-shaped dentary which is narrowly V-shaped in Labidochromis . The presence of teeth consisting of narrow shafts with recurved, spoonlike, compressed crowns distinguishes Cyathochromis from Chindongo . The isognathic to slightly retrognathic jaws of Chindongo distinguish it from Genyochromis which possess a prognathic mouth with a strong chin. Chindongo is distinguished from Melanochromis by a lack of longitudinal stripes in its flank melanin pattern and by the absence of a sex-related reversal in the color pattern which characterizes the latter. Iodotropheus can be distinguished by a narrow U-shaped dentary with a width about 3/4 of its length while that in Chindongo is as wide as long.

Chindongo is distinguished from Pseudotropheus (here characterized by its type species P. williamsi and by P. brevis ) by a smaller mouth with relatively large outer teeth. The outer row teeth in Pseudotropheus are about twice the size of those in the second row, while in Chindongo the outer row teeth are 4–10 times as large ( Fig. 8 ). Chindongo is characterized by a melanin pattern consisting of vertical bars on the flank while the pattern in Pseudotropheus consists of two longitudinal bands of spots. Chindongo differs from Tropheops by the placement of the teeth in the dentary; in Chindongo all teeth are implanted at about the same plane and the dentigerous area extends posteriorly to about halfway the coronoid process, while in Tropheops almost all teeth are anterior of the coronoid process and the anterior most teeth are implanted at a considerably lower level (the crown tips of the larger anterior teeth are at about the same level as those of the minute posterior teeth) ( Fig. 9 ). Chindongo differs from Tropheops and Metriaclima by a consistently different range in the angle of the vomer (53–68° in Chindongo vs. 71–96° in Tropheops vs. 32–49° in Metriaclima ).

Representatives of Chindongo are further diagnosed by their feeding technique. Members of Chindongo feed mostly on aufwuchs extracting loose material (diatoms and cyanobacteria) from the algal matrix on rocks by biting ( Konings 2007), and they feed at a 30–60° angle to the substrate ( Stauffer & Posner 2006). They favor patches with a lush growth so that the bites yield sufficient food. In order to prevent other algae-eaters access to such lush aufwuchs, members of Chindongo protect their feeding grounds aggressively with most species defending socalled algal gardens. Members of Metriaclima rake the algal matrix with their teeth collecting only the loose material while Tropheops species feed by shearing and twisting algal strands from the substrate. Pseudotropheus ( P. williamsi and P. brevis ) do not feed on algae but instead on insects that fall on the water surface or even by jumping partly out of the water snapping lake flies hovering above the surface ( Konings 2007).

In addition to the newly described C. bellicosus , we assign the following species, which were previously in Pseudotropheus , to Chindongo : C. ater , C. cyaneus , C. demasoni , C. elongatus , C. flavus , C. heteropictus , C. longior , C. minutus , C. saulosi , and C. socolofi .

Etymology. The name Chindongo is a commonly-used name for “small, rock-dwelling fish” in the local vernacular of Malaŵi. The gender is masculine.

Figures

FIGURE 8. Occlusal view of the dentary Chindongo bellicosus (A) and Pseudotropheus williamsi (B). Note that the outer-row teeth of Chindongo (A) are much larger than those of the second row while those of P. williamsi are only slightly larger (B).

FIGURE 9. Occlusal view of the dentary Chindongo bellicosus (A) and Tropheops kamtambo (B). In Chindongo all teeth are implanted at about the same plane and the dentigerous area extends posteriorly to about halfway the coronoid process, while in Tropheops almost all teeth are anterior of the coronoid process and the anterior most teeth are implanted at a considerable lower level.