A new miniature killifish of the genus Melanorivulus (Cyprinodontiformes: Rivulidae) from the Xingu river drainage, Brazilian Amazon

Melanorivulus rubroreticulatus, new species, is described on the basis of material collected in the lower section of the Xingu river drainage, Brazilian Amazon. It is a member of a group endemic to the region encompassing the southern Amazonas river tributaries and the Parnaíba river basin. The new species is distinguished from other congeners of this group by the presence of broad red bars on the caudal fin in males, bars often interconnected to form reticulations, and short red bars contrasting with intense light blue ground colour on the anal-fin base. It represents the northern-most record for the group, besides being the only species occurring in the Amazon rain forest and possibly is also the smallest one, barely surpassing 25 mm of standard length

Five new species of the killifish genus Anablepsoides from the Brazilian Amazon (Cyprinodontiformes: Rivulidae)

Two new species of the Anablepsoides urophthalmus group and three new species of the A. ornatus group, collected in the Brazilian Amazon, are described. Anablepsoides jari, new species, and A. roraima, new species, are the first records of members of the A. urophthalmus group for tributaries of the Amazonas river basin draining the Guiana Shield, but phylogenetic relationships of these species with other taxa are still uncertain. Anablepsoides jari, from the Jari river drainage, is distinguished from congeners by the colour pattern of flank and unpaired fins in males, whereas Anablepsoides roraima, from the Branco river drainage, is distinguished by the spotted pattern of flank in males. Relationships of the three new species of the A. ornatus group, Anablepsoides henschelae, new species, Anablepsoides ottonii, new species, and Anablepsoides gamae, new species, are tentatively inferred upon the basis of derived colour patterns of caudal fin in males, which are also informative to diagnose each new species. Anablepsoides ottonii seems to be closely related to A. ornatus by both sharing a pointed caudal fin in larger specimens and the presence of reddish brown spots on the dorsal portion of the caudal fin in males, whereas A. gamae and A. amanan share a colour pattern of caudal fin in males, unique among aplocheiloids, in which the dorsal portion of the fin is orangish red with dorsal margin white and narrow black outer border. Anablepsoides henschelae is considered as the sister group to all other species of its group by not sharing an apomorphic asymmetrically coloured caudal fin in males

A new species of Laetacara from the northern Brazil coastal floodplains (Teleostei: Cichlidae)

Laetacara flamannellus sp. n. is described from the northern Brazilian coastal floodplains. It differs from all its congeners by a combination of character states: presence of a dark brown or black spot located on dorsal-fin base; presence of a yellow stripe on the middle portion of the dorsal fin, crossing the whole fin; presence of an orange ring around the dorsal-fin base spot; absence of a red pigmentation on belly; absence of a red or purple zone on the anal-fin base; absence of a red zone on the caudal-fin base; cycloid scales on the opercle plate; and trunk scales above upper lateral line with few ctenii. The presence of a deep notch in the dorsal margin of the anterior ceratohyal, often used as diagnostic for Laetacara, is confirmed here for L. flamannellus

A new miniature killifish of the genus Melanorivulus (Cyprinodontiformes: Rivulidae) from the coastal plains of north-eastern Brazil

Melanorivulus atlanticus, new species, is described on the basis of specimens collected in the coastal plains of north-eastern Brazil, constituting the first record of the genus for the Atlantic Forest biogeographical province. The new species together M. decoratus and M. jalapensis form a clade of small species, not surpassing 20 mm SL, mainly diagnosed by the presence of five branchiostegal rays. Melanorivulus atlanticus differs from those two species by a narrow black border along the entire caudal fin in males and the presence of 2 + 1 neuromasts in the mandibular series, besides differing from all congeners by having sexually dimorphic pelvic fin, which is pointed and with seven rays in males, elliptical and with five rays in females. The description of M. atlanticus expands in 670 km to east the known geographic range of the genus

Integrative taxonomy reveals hidden diversity in the southern African darters genus Nannocharax Günther 1867 (Characiformes: Distichodontidae):

The present study explored the diversity of Nannocharax within southern Africa by implementing three species delimitation methods for a data set consisting of 37 mitochondrial cytochrome oxidase subunit I sequences. Two unilocus coalescent methods, the General Mixed Yule Coalescent (GMYC) and the Bayesian implementation of the Poisson Tree Processes (bPTP), and a genetic distance method, the Automatic Barcode Gap Discovery (ABGD), were applied. Both GMYC and bPTP delimited the same operational taxonomic units (OTUs), revealing a higher diversity for the genus in the region than previously recognised, whereas the ABGD failed to delimit the same candidate species

Nothobranchius balamaensis (Cyprinodontiformes: Nothobranchiidae), a new species of annual killifish from northern Mozambique

Bragança, Pedro H. N., Bellstedt, Dirk U., Merwe, P. De Wet Van Der, Cotterill, Fenton P.D., Watters, Brian R., Chakona, Albert (2022): Nothobranchius balamaensis (Cyprinodontiformes: Nothobranchiidae), a new species of annual killifish from northern Mozambique. Zootaxa 5174 (5): 508-524, DOI: 10.11646/zootaxa.5174.5.