Chiloglanis pojeri Poll 1944

Friel, John P. & Vigliotta, Thomas R., 2011, Three new species of African suckermouth catfishes, genus Chiloglanis (Siluriformes: Mochokidae), from the lower Malagarasi and Luiche rivers of western Tanzania, Zootaxa 3063, pp. 1-21 : 19

Validity of Chiloglanis pojeri Poll 1944 and Chiloglanis micropogon Poll 1952

Our review of Chiloglanis type specimens during this study convinced us that a least two nominal species that have been subsequently synonymized by other researchers are in fact distinct taxa that should be resurrected as valid species.

First, we recognize both Chiloglanis lukugae Poll 1944 and Chiloglanis pojeri Poll 1944 as valid species. These species were described in the same publication from Congo basin tributaries west of Lake Tanganyika. Ng & Bailey (2006: 11) recognized, based solely on their comparison of Poll’s original descriptions and the close proximity of the type localities ( Fig. 2 ), C. pojeri as a subjective junior synonym of C. lukugae . This interpretation seemed surprising as Poll’s original descriptions contained illustrations that clearly depict several differences between these species including the size and shape of the oral disc, the length of the mandibular barbels and the disposition of the mandibular teeth. Photographs of the holotypes for both species (IRSNB 72 for C. lukugae (image available at http://acsi.acnatsci.org/base/getthumbnail.php?mode=full&target=134557)) & IRSNB 74 for C. pojeri (image available at http://acsi.acnatsci.org/base/getthumbnail.php?mode=full&target=136196) confirm that these differences are real, and that the specimens are not conspecific.

Second, we recognize both Chiloglanis batesii Boulenger 1904 (type locality in southern Cameroon) and Chiloglanis micropogon Poll 1952 (type locality in eastern DR Congo) as valid species. Despite the considerable distance between these type localities, Roberts (1989: 152) recognized C. micropogon as a subjective junior synonym of C. batesii based on his examination of both type and non-type specimens. This synonymy made C. batesii the most broadly distributed Chiloglanis species ranging from the Niger to Congo basins. Our examination of both type and non-type specimens of these nominal species does not support this synonymy. While both species do share a few features in common (e.g., reduced mandibular barbels along the posterior edge of the oral disk, and an elongated upper lobe of the caudal fin in sexually mature males), there are also consistent differences between them. In comparing these species we find the following features of the mouth and lips can be used to distinguish them from each other ( Fig. 7 ): the presence of a distinctive pair of papillae on the roof of the oral cavity in C. micropogon vs. the absence of such structures in C. batesii ; a greater number of dentary teeth in C. micropogon vs. C. batesii when comparing similarly sized specimens; relatively blunt tipped teeth in C. micropogon vs. acutely pointed teeth in C. batesii , and a relatively continuous ridge of soft tissue directly posterior to dentary teeth in C. micropogon vs. a row of several papillae in C. batesii .

Figures

FIGURE 2. Map of the general area surrounding Lake Tanganyika showing the type localities of three new Chiloglanis species (white square & star) along with those of 16 additional Chiloglanis species previously described from the region (black circles). For those species displaying secondary sexual dimorphism of the caudal fin in adult males, a silhouette of the fin is illustrated.

FIGURE 7. Ventral view of the head illustrating morphological differences in the mouth and oral disc. A. Chiloglanis batesii, MRAC 94 - 049 - P- 0517 - 0549, Cameroon, Mvi River, Sanaga basin; B. Chiloglanis micropogon, MRAC 91479, holotype, Democratic Republic of the Congo Nzokwe River, Ulindi basin. Arrows point to a pair of prominent papillae present on the roof of the oral cavity. Photo by T. R. Vigliotta. Scale bar equals 1 cm.