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Volume 26, Issue 3-4 – 30 November 2020

Volume 26, Issue 3-4 – 30 November 2020
New Scientific publication – started delivery on December 01, 2020

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Tyson R. Roberts: Two new species of the spiny percheel genus Mastacembelus (Synbranchiformes, Mastacembelidae) with low numbers of dorsal fin spines from the Congo basin, pp. 69-76

Abstract

Two new species of African Mastacembelus are described with unusually low counts of dorsal fin spines. Until now the African species of spiny eels with the fewest dorsal fin spines are M. paucispinis Boulenger 1899, from mainstream rapids of the Lower Congo River, with 6-10 dorsal fin spines, well-developed eyes but obsolescent coloration, and M. sexdecimspinus (Roberts and Travers 1986) from high gradient rapids of Cross River, near Widekum, Cameroon, with 15-16 dorsal fin spines and well-developed coloration. The new species are M. ubangipaucispinis from mainstream rapids of the Ubangi River in the Congo basin, with 10 dorsal fin spines and well developed distinctive color pattern (similar to the obsolescent color pattern of M. paucispinis), and M. kadeiensis, from the Kadei River, Congo basin, Central African Republic, with 19 dorsal fin spines and a distinctive color pattern. The rest of African Mastacembelus have 21-40 dorsal fin spines and a different color pattern from the two new species. Mastacembelus ubangipaucispinis shows similarities with M. paucispinis, differing mainly in well-developed (versus poorly developed but otherwise similar) color pattern and in having fewer dorsal fin rays, 101 versus 115-123. Mastacembelus kadeiensis is perhaps most similar to M. sexdecimspinus and somewhat less closely to M. ubangipaucispinis and M. paucispinis. The holotype of Mastacembelus frenatus Boulenger 1901 from Lake Tanganyika reportedly has only 18 dorsal fin spines but coloration unlike M. kadeiensis. A radiograph reveals that it actually has 26 dorsal fin spines.

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Mastacembelus ubangipaucispinis n. sp., holotype, NRM 64699, 207 mm. a. lateral view; b. dorsal view; c. ventral view; d. radiograph lateral view.

Frank Pezold, Kassandra Ford and Ray C. Schmidt: Epiplatys cashneri, A New Species of Killifish (Cyprinodontiformes: Nothobranchiidae) from Liberia, West Africa, pp. 77-86

Abstract

A new species of killifish, Epiplatys cashneri, is describedfrom tributaries of the Geebo and Dugbe rivers, in southern Liberia. It differs from all other Epiplatys species in its distinctive coloration. Males have an orange body with red spots and reddish orange median fins with dark red spots and dark red margins. Females are yellow with red spots and have yellow median fins with red spots. There are no longitudinal dark bands or broad dark crossbars on the trunk and metallic blue highlights are limited to head, nape and trunk above pectoral fins in males. The species is known to the aquarium trade as “Orange Liberia.”

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Epiplatys cashneri, female, unnamed tributary to Gblanee Creek NE of Tuzon (5.10209578 N, 8.49228 W), 87 m elev., 1-4 m wide, 7 February 2014. Photo by B. Ahearn, F. Pezold and R. Schmidt.

Tyson R. Roberts: Nasutoryzias ataranensis new genus and species, a Slender Adrianichthyid Fish with specialized oral and pharyngeal teeth and pectoral fins covered with Melanophores from the lower Salween basin, Myanmar, pp. 87-92

Abstract

The new genus and species described here from the Lower Salween basin in Myanmar, Nasutoryzias ataranensis, differs from other members of the beloniform family Adrianichthyidae in having upper and lower jaws equally projecting when mouth is closed, greatly enlarged central upper jaw teeth and tricuspid rather than simply conical pharyngeal teeth, mid-water swimming habits, pectoral fins uniformly covered with melanophores, and short pelvic fins. Food habits and reproductive behavior unknown. Sexual dimorphism apparently absent. Phyletic relations to other members of the family unknown but possibly close to slender-bodied species of Oryzias from India (including two newly discovered but still undescribed species) and Thailand.

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Nasutoryzias ataranensis, holotype, NRM 48240, 21.0 mm. a. head in dorsal view; b. body in lateral view.

Tyson R. Roberts: The first two species of South American freshwater stingrays of the genus Potamotrygon, reported from the Orinoco Basin of Colombia by François Roulin in 1829, pp. 92-112

Abstract

French naturalist and explorer François Désiré Roulin (1796-1874) reported the first two known species of the freshwater potamotrygonid stingray genus Potamotrygon from the Orinoco basin, Upper Rio Meta in the Province of San Martin near Bogota, Colombia (Roulin 1829a,b). These were known to the local Indians as Pastenague or Raya tachetée, and Raya cascabel or Pastenague noire. They regarded the former as toxic and inedible, the latter as non-toxic and edible. The Pastenague noire was described and named Pastenagus humboldtii Roulin, 1829b), based on a specimen 424 mm disc width that was not kept. Roulin did not obtain any material of the Pastenague tachetée. In 1877 Garman named the genus Potamotrygon, selecting Potamotrygon humboldtii (Roulin 1829), earliest named species in the genus as its type species. At the same time he indicated Potamotrygon histrix (Müller and Henle in Valenciennes 1839, type locality Buenos Aires, Argentina) as identical with P. humboldtii. No additional specimens of P. humboldtii have been reported. Jordan selected Trygon hystrix Müller & Henle 1841 [=Trygon hystrix Müller & Henle 1839] as type species of Potamotrygon (Jordan, 1919: 389). This type species designation has been accepted by subsequent authors including Séret & McEachran, 1987: 6. At the request of the author, Heiko Bleher visited Roulin’s Orinocan collecting locality in 2015 in order to collect his two supposed species of Potamotrygon. Unfortunately, the region has now been completely destroyed by deforestation, palm oil plantations and oil drilling and Bleher was able to succeed only in obtaining a single specimen of the undescribed Pastinague tachetée. This specimen is described here as Potamotrygon roulini new species. French naturalist and explorer François Désiré Roulin (1796-1874) reported the first two known species of the freshwater potamotrygonid stingray genus Potamotrygon from the Orinoco basin, Upper Rio  Meta in the Province of San Martin near Bogota, Colombia (Roulin 1829a,b). These were known to the local Indians as Pastenague or Raya tachetée, and Raya cascabel or Pastenague noire. They regarded the former as toxic and inedible, the latter as non-toxic and edible. The Pastenague noire was described and named Pastenagus humboldtii Roulin, 1829b), based on a specimen 424 mm disc width that was not kept. Roulin did not obtain any material of the Pastenague tachetée. In 1877 Garman named the genus Potamotrygon, selecting Potamotrygon humboldtii (Roulin 1829), earliest named species in the genus as its type species. At the same time he indicated Potamotrygon histrix (Müller and Henle in Valenciennes 1839, type locality Buenos Aires, Argentina) as identical with P. humboldtii. No additional specimens of P. humboldtii have been reported. Jordan selected Trygon hystrix Müller & Henle 1841 [=Trygon hystrix Müller & Henle 1839] as type species of Potamotrygon (Jordan, 1919: 389). This type species designation has been accepted by subsequent authors including Séret & McEachran, 1987: 6. At the request of the author, Heiko Bleher visited Roulin’s Orinocan collecting locality in 2015 in order to collect his two supposed species of Potamotrygon. Unfortunately, the region has now been completely destroyed by deforestation, palm oil plantations and oil drilling and Bleher was able to succeed only in obtaining a single specimen of the undescribed Pastinague tachetée. This specimen is described here as Potamotrygon roulini new species.

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Potamotrygon roulini, holotype, disc width 201 mm.: a. dorsal view when alive (photograph H. Bleher)

 

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