A New Species of Banded Nannocharax from the Luapula River Basin, Zambia, Africa (Cithariniformes: Distichodontidae)
A new species of Nannocharax is described from the Luongo and Kalungwishi Rivers, tributaries of the Luapula River in the northeastern region of Zambia. The new species differs from its congeners by a combination of characters, such as the body coloration pattern formed by a series of one-scale-wide vertical bars, a small caudal-peduncle spot surrounded by a light clear area at the base of the middle caudal-fin rays, and a low number of scales in the circumpeduncular series and lateral line series. The new species is also distinguished from other members of the Nannocharax multifasciatus species-group by genetic distances ranging from 10.3% to 11.6% with DNA barcoding. Likewise, distance and coalescent molecular species delimitation approaches recovered the new species as an independent operational taxonomic unit. Newly generated hypotheses of phylogenetic relationships based on maximum likelihood and Bayesian inference for the new taxon are provided.
Nannocharax skeltoni, CUMV 100101, 22.6 mm SL, holotype, Zambia, Luapula, Luongo River drainage, Lufubo River falls below bridge at Chipili on Mansa-Mununga road.
Map of the southern region of Africa with geographical distribution (red diamonds) and type locality (white star) of Nannocharax skeltoni in Luapula River. The type locality of N. machadoi (white star) and the geographical distribution of the analyzed material in the Zambezi (blue squares) and Okavango (blue dots) river basins are also shown.
Nannocharax machadoi, UMMZ 200141, 20.6 mm SL, Kafue River, 5 km West of rail bridge at Kafue, Zambia.
Scatterplot between (A) PC I x PC II and (B) PC II x PC III from principal component analysis on 20 log-transformed measurements from Nannocharax skeltoni (n = 23, red diamonds) and N. machadoi from the Zambezi (n = 17, blue squares) and Okavango (n = 29, blue dots) river basins.
Phylogenetic tree based on Bayesian reconstruction of 652 base pairs of Cytochrome Oxidase subunit 1 (COI). Circles represent the posterior probability values at each node generated by BEAST2*. Highlighted clades represent the five species within the ingroup, as follows: Nannocharax skeltoni, new species (red); Nannocharax machadoi (blue), Nannocharax minutus (green), Nannocharax multifasciatus (purple), and Nannocharax wittei (turquoise). Nannocharax dageti and Nannocharax cf. lineostriatus were used as outgroups. Lateral sidebars correspond to molecular species delimitation through the general mixed Yule Coalescent (GMYC), Bayesian implementation of the Poisson tree processes (bPTP), and the automatic barcode gap discovery (ABGD). See Data Accessibility for tree file.
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