[Ichthyology • 2025] Heteromormyrus dolichorhynchus, H. angusticaudata, H. tangwenai, ... • Review of the southern African Slender Stonebashers, Genus Heteromormyrus Steindachner 1866 (Teleostei: Mormyridae), with Description of Six New Species

Heteromormyrus dolichorhynchus, H. angusticaudata,
H. xanekweorum, H. chilembwei, 
H. tangwenai and H. ndauorum 

Mutizwa, Kadye, Bragança & Chakona, 2025

  DOI: doi.org/10.1111/jfb.70191 

 Researchgate.net/publication/395577925

Abstract

Recent molecular studies have advanced our knowledge of the taxonomic diversity and generic placement of the slender stonebashers, previously placed in the genus Hippopotamyrus, in southern Africa. These fishes were recently transferred to the genus Heteromormyrus whose range encompasses the Kwanza, Kunene, Okavango, Zambezi, Pungwe and Buzi River systems in southern Africa, as well as the southern tributaries of the Congo River system. The present study builds on previous research that identified at least eight candidate species within the Heteromormyrus ansorgii species complex by providing formal descriptions for six new species and redescriptions of Heteromormyrus pauciradiatus and H. ansorgii s.s. The Kwanza River system is peculiar because it currently has five known species in this genus, some of which are co-distributed, whereas the other river systems have only one or two species in this genus. Two of the new species, Heteromormyrus dolichorhynchus sp. nov. and Heteromormyrus angusticaudata sp. nov., are endemic to the Kwanza River system. Heteromormyrus xanekweorum sp. nov. is confined to the Okavango River system, Heteromormyrus chilembwei sp. nov. occurs in the Ruo River (lower Zambezi River system), Heteromormyrus tangwenai sp. nov. is endemic to the Pungwe River system and Heteromormyrus ndauorum sp. nov. is endemic to the Buzi River system. Species in this genus exhibit high morphological similarity, but they can be separated by a combination of characters, including scale counts, dorsal- and anal-fin ray counts, vertebral counts, caudal peduncle depth, position of nostrils, head shape and variation in colour pattern. Taxonomic diversity within this genus is likely to be higher than currently known, and future studies, particularly in the Kwanza and upper Zambezi rivers, are anticipated to uncover additional new species.

Keywords: diversity, freshwater, mormyrids, southern Africa, taxonomy

Heteromormyrus dolichorhynchus sp. nov. 

Heteromormyrus angusticaudata sp. nov.

Heteromormyrus xanekweorum sp. nov. 

Heteromormyrus chilembwei sp. nov. 

 Heteromormyrus tangwenai sp. nov. 

 Heteromormyrus ndauorum sp. nov.

The range of colour patterns observed in Heteromormyrus lineages and species from southern Africa. 
 (b) Heteromormyrus sp. ‘K5’ (SAIAB 203161) had a clearly visible dark blotch present near the flexion point of the caudal fin.
(c) Heteromormyrus sp. ‘K3’ (SAIAB 84790) had a clearly visible dark blotch present near the flexion point of the caudal fin and a dark vertical bar just anterior to this blotch.
 (d) Heteromormyrus sp. ‘K1’ (SAIAB 85039) had a series of clearly visible thin curved vertical bars that were more conspicuous in the anterior portion of the flank.

 Scale bar = 1 cm.

 

Tadiwa I. Mutizwa, Wilbert T. Kadye, Pedro H. N. Bragança and Albert Chakona. 2025. Review of the southern African Slender Stonebashers, Genus Heteromormyrus Steindachner 1866 (Teleostei: Mormyridae), with Description of six new species. Journal of Fish Biology. DOI: doi.org/10.1111/jfb.70191 [17 September 2025] 

 Researchgate.net/publication/395577925_Review_of_Heteromormyrus_with_description_of_six_new_species

[Ichthyology • 2024] Pollimyrus ibalazambai, P. krameri, ... • Morphometric Synthesis of Pollimyrus (Osteoglossiformes: Mormyridae) with the Description of Four New Species

 

 Pollimyrus ibalazambai 
Pollimyrus krameri 
 Pollimyrus weyli 

Dierickx, Lunkayilakio, Bills & Vreven, 2024

DOI: doi.org/10.1111/jfb.15983

Abstract

Mormyridae, a species-rich family endemic to Africa, remains taxonomically understudied. This has been the case for the genus Pollimyrus Taverne, 1971, which hinders further understanding of the distribution, ecology, and conservation of its species. Therefore, an in-depth morphometric comparison of all currently valid species is carried out using most of the available type specimens. Species delineations were re-evaluated, and four species new to science described: Pollimyrus ibalazambai sp. nov. (the Luki River, the Democratic Republic of the Congo), Pollimyrus krameri sp. nov. (the Lugenda River, Mozambique), Pollimyrus vanneeri sp. nov. (the Kouilou-Niari River, the Republic of the Congo), and Pollimyrus weyli sp. nov. (the Buzi River, Mozambique). In this study, Pollimyrus guttatus is confirmed to belong to Pollimyrus, whereas Pollimyrus eburneensis and Cyphomyrus plagiostoma seem more similar to species allocated to other genera. No or only little morphological differences were found between the type series of several species, which could indicate the need for synonymization of these species (Pollimyrus cuandoensis with Pollimyrus marianne and Pollimyrus nigripinnis with Pollimyrus pulverulentus). As such 20 species are currently morphologically identifiable in the genus Pollimyrus. The present study highlights the critical need for further synthetic efforts and new collecting efforts across Africa for this and other Mormyridae genera.

Keywords: morphology, Pollimyrus ibalazambai sp. nov., Pollimyrus krameri sp. nov., Pollimyrus vanneeri sp. nov., Pollimyrus weyli sp. nov., taxonomy

 

Class Actinopterygii Klein, 1885

Order Osteoglossiformes Berg, 1940

Family Mormyridae Bonaparte, 1831

Subfamily Mormyrinae Bonaparte, 1831

Genus Pollimyrus Taverne, 1971

Pollimyrus Taverne, 1971: 140 

(type species: Mormyrus isidori Valenciennes, 1847, by original designation).i

Pollimyrus ibalazambai sp. nov.

Etymology: The specific epithet is a noun honoring Professor Dr. Armel Ibala Zamba (1975–) (Université Marien Ngouabi, the Republic of the Congo) for his contributions to African ichthyology and his work in the Luki River basin (DRC) within the framework of his PhD (2005–2010).

Pollimyrus krameri sp. nov.

Etymology: The specific epithet is a noun honoring Professor Dr. Bernd Kramer (1943–) (University of Regensburg, Germany) for his contributions to ichthyology and study of weakly electric fish, southern African Mormyridae in particular.

Photograph of dead, but not yet fixed, holotype specimen of Pollimyrus krameri sp. nov. (South African Institute for Aquatic Biodiversity [SAIAB] 73892: 45.6 mm SL [standard length]) from the Lugenda River (by R.B., August 22, 2003).
Photograph of dead, but not yet fixed, holotype of Pollimyrus weyli sp. nov. (South African Institute for Aquatic Biodiversity [SAIAB] 67639: 51.43 mm SL [standard length]) from the Mussapa River (by R.B., September 27, 2002).
Photograph of a live type specimen of Pollimyrus ibalazambai sp. nov. from the Luki River, near the Kimbozi Bridge (by S.W.L., Mbisa-Congo I, August 10, 2016).

Pollimyrus vanneeri sp. nov.

Etymology: The specific epithet is a noun honoring Professor Dr. Wim Van Neer (1954–) (Royal Belgian Institute of Natural Sciences, Brussels, and KU Leuven, Leuven, Belgium) for his contributions to ichthyoarchaeology in Europe and northern Africa.

Pollimyrus weyli sp. nov.

Etymology: The specific epithet is a noun honoring the late Professor Dr. Olaf L.F. Weyl (1972–†2020) (SAIAB) for his contributions to African ichthyology and his work in the Buzi River system within the framework of his PhD, expanding the collections housed at SAIAB and increasing the understanding of the biodiversity in the region.

 

Katrien Dierickx, Soleil Wamuini Lunkayilakio, Roger Bills and Emmanuel Vreven. 2024. Morphometric Synthesis of Pollimyrus (Teleostei, Mormyridae) with the Description of Four New Species. Journal of Fish Biology. DOI: doi.org/10.1111/jfb.15983

[PaleoIchthyology • 2024] Macroprosopon hiltoni • A Long-snouted marine Bonytongue (Teleostei: Osteoglossidae) from the early Eocene of Morocco and the Phylogenetic Affinities of Marine osteoglossids

Macroprosopon hiltoni

 Capobianco, Zouhri & Friedman, 2024

DOI: 10.1093/zoolinnean/zlae015

 twitter.com/acapomorphic

 life reconstruction by Sky Jung

 

Abstract

Osteoglossid bonytongues (arapaimas, arowanas, and relatives) are extant tropical freshwater fishes with a relatively abundant and diverse fossil record. Most osteoglossid fossils come from a 25-million-year interval in the early Palaeogene, when these fishes were distributed worldwide in both freshwater and marine environments. Despite their biogeographic and palaeoecological relevance, and a relative abundance of well-preserved material, the evolutionary relationships between these Palaeogene forms and extant bonytongues remain unclear. Here we describe a new genus of bonytongue from early Eocene marine deposits of Morocco, represented by an articulated, three-dimensionally preserved skull with associated pectoral girdle. This taxon is characterized by an elongated snout, contrasting with the short jaws usually found in marine representatives of the clade. A revision of morphological characters in bonytongues allows us to place this new genus, together with other marine and freshwater Eocene taxa, within crown osteoglossids and closely related to extant arapaimines. The discovery of the new Moroccan taxon hints at a previously underestimated eco-morphological diversity of marine bonytongues, highlighting the diverse trophic niches that these fishes occupied in early Palaeogene seas.

computed tomography, fish, fossil evidence, Palaeogene, phylogeny, Osteoglossoidei

Macroprosopon hiltoni

Alessio Capobianco, Samir Zouhri and Matt Friedman. 2024. A Long-snouted marine Bonytongue (Teleostei: Osteoglossidae) from the early Eocene of Morocco and the Phylogenetic Affinities of Marine osteoglossids. Zoological Journal of the Linnean Society. zlae015. DOI: 10.1093/zoolinnean/zlae015

 twitter.com/acapomorphic/status/1780939719259357327

  

[PaleoIchthyology • 2022] Harenaichthys lui • A New Species of Osteoglossomorpha (Actinopterygii: Teleostei) from the Upper Cretaceous Nemegt Formation of Mongolia: Paleobiological and Paleobiogeographic Implications

 

Harenaichthys lui

Kim, Lee, Park, Lee, Winkler, Jacobs & Barsbold, 2022

 DOI: 10.1016/j.cretres.2022.105214 

 facebook.com/jyp4u

Highlights: 

• All Nemegt specimens represent a new genus and species of osteoglossomorph fish, Harenaichthys lui gen. et sp. nov., including old materials.

• A fish centrum found with Raptorex kriegsteini is assigned to Harenaichthys; thereby, Raptorex is from the Upper Cretaceous Nemegt Formation of Mongolia.

• The monospecific assemblages of Harenaichthys were affected by the high altitude of their habitat.

Abstract

Compared to abundant dinosaur faunas, fish materials are scarce in the Nemegt Formation (Maastrichtian) of Mongolia except for isolated centra assigned to the Hiodontidae (Osteoglossomopha). Here we report new additional fish materials collected from the Nemegt Formation. They include skull parts (quadrate, premaxilla, and dentary), isolated and articulated centra, and a caudal fin. New specimens appear to be the same taxon as the previously reported samples from the Nemegt Formation based on morphological similarities in the abdominal centra. However, all specimens represent a new genus and species of osteoglossomorph fish, Harenaichthys lui gen. et sp. nov. Phylogenetic analysis reveals that Harenaichthys is a basal member of the osteoglossomorphs instead of being included in the hiodontids. The comparison of Harenaichthys with Chinese osteoglossomorph Xixiaichthys tongxinensis and a fish centrum found along with the theropod dinosaur Raptorex kriegsteini supports a previous conclusion that R. kriegsteini comes from the Nemegt Formation. Unusual monospecific occurrences of Harenaichthys in many localities allow us to understand their paleoecology and paleobiogeography better. In addition, the pathologic features seen on some centra of Harenaicthys indicate that they suffered from various diseases in life.

Keywords: Osteoglossomorpha, Raptorex kriegsteini, Monospecific lag deposits, Pathology, Nemegt Formation, Mongolia

Harenaichthys lui gen. et sp. nov. 

 

Su-Hwan Kim, Yuong-Nam Lee, Jin-Young Park, Sungjin Lee, Dale A. Winkler, Louis L. Jacobs and Rinchen Barsbold. 2022. A New Species of Osteoglossomorpha (Actinopterygii: Teleostei) from the Upper Cretaceous Nemegt Formation of Mongolia: Paleobiological and Paleobiogeographic Implications. Cretaceous Research. In Press, 105214. DOI: 10.1016/j.cretres.2022.105214

  facebook.com/jyp4u/posts/4922882181114028

[PaleoIchthyology • 2017] Scleropages sinensis • First Complete Fossil Scleropages (Osteoglossomorpha) from the early Eocene, Hubei, China

Scleropages sinensis 

Zhang & Wilson, 2017

IVVP.cas.cn

Abstract
A new species of osteoglossid fish, Scleropages sinensis sp. nov., is described from the Early Eocene Xiwanpu Formation in Hunan and the Yangxi Formation in Hubei, China. The new species was attributed to Scleropages, an extant genus of Osteoglossidae, because it very closely resembles the genus in skull bones, caudal skeleton, the shape and position of fins, and reticulate scales. The new fish is very similar to extant Scleropages except: the nasals do not appear to be ornamented; the sensory pore in the antorbital is large; the posterior infraorbitals are not quite covering the dorsal limb of the preopercle; the posteroventral angle of the preopercle is produced to point; the posteroventral margin of the opercle is concave and the ventral end of the bone is produced to a point; the pectoral fin is very long and extends well behind the beginning of the pelvic fin; the vertebral count is about 46–48; the parapophyses are shorter and the upper and lower caudal rays are nearly as long as the inner rays. The new fish is closer to its Asian neighbor, S. formosus, than to its southern relative, S. leichardti. Scleropages formosus inhabits natural lakes, swamps, flooded forests, and slowly moving, deep parts of rivers with overhanging vegetative cover. It is a carnivorous fish and its food consists mainly of insects, fishes, worms, small amphibians, small mammals, and even birds. S. sinensis may live in the same natural environment and have a similar diet except for the largest items. Sexual dimorphism may exist in S. sinensis. The presumed male has a slimmer and shallower body, a relatively larger head, and a deeper mouth cleft. The discovery of Scleropages sinensis sp. nov. dates the divergence of Scleropages and Osteoglossum to no later than the Early Eocene.

 Key words: Hunan, Hubei, China; Early Eocene; Xiawanpu Formation; Yangxi Formation; Osteoglossidae

Systematic paleontology

Teleostei Müller, 1846
Osteoglossomorpha Greenwood et al., 1966
Osteoglossidae Bonaparte, 1832
 Scleropages Günther, 1864

Scleropages sinensis sp. nov.







Holotype: IVPP V 13672.2, a complete skeleton.
Referred specimens: IVPP V 12749.1–8, V 12750, V 13672.1, 3.

Locality and horizon: Specimens V 13672.1–3 and V 12750 are from Songzi County, Hubei Province, China; Yangxi Formation, Lower Eocene. Specimens V 12749.1–8 are from Xiangxiang, Hunan Province, China; Xiawanpu Formation, Eocene.

Etymology: The specific name refers to China where the specimens were found.

 Jiang-Yong Zhang and Mark V H Wilson. 2017. First Complete Fossil Scleropages (Osteoglossomorpha).  Vertebrata PalAsiatica. 55(1); 1–23

ResearchGate.net/publication/312550523_First_complete_fossil_Scleropages_Osteoglossomorpha

http://www.ivpp.cas.cn/cbw/gjzdwxb/xbwzxz/201701/t20170118_4738296.html

http://www.ivpp.cas.cn/cbw/gjzdwxb/xbwzxz/201701/P020170118570249232098.pdf

[Ichthyology • 2013] Scleropages formosus (Müller & Schlegel, 1840) • The Types of Osteoglossum formosum Müller & Schlegel, 1840 (Teleostei, Osteoglossidae)

Osteoglossum formosum Müller & Schlegel, 1840

From Müller & Schlegel 1840-1845

Abstract 

The designation of a neotype for Scleropages formosus (Müller & Schlegel, 1840) by Pouyaud et al. (2003) triggered a search for the type specimens of the species, which were found in the collections of the Naturalis Biodiversity Center, Leiden (RMNH) and the Natural History Museum, London (BM(NH)). The publication date of the species is corrected. Moreover, detailed data on the day of capture and the type locality were uncovered. An English translation of the major part of the original Dutch description is provided, and a number of neglected colour descriptions and figures of S. formosus are discussed. Lastly, a lectotype is designated.

Key words: Scleropages formosus, Asian Arowana, neotype, lectotype, RMNH collection

FIGURE 10. Type specimens of Osteoglossum formosum Müller & Schlegel 1840.
A. RMNH.PISC. 3386a, 475 mm TL. Lectotype;
B. RMNH.PISC.3386b, 370 mm TL. Paralectotype;
C. RMNH.PISC.S.366, 580 mm TL, Paralectotype, mirror image.

Scale equals 5 cm.

van Oijen, Martien J. P. & Sancia E. t. V. D. Meij. 2013. The Types of Osteoglossum formosum Müller & Schlegel, 1840 (Teleostei, Osteoglossidae). Zootaxa. 3722(3): 361-371.

http://www.mapress.com/zootaxa/2013/f/zt03722p371.pdf

[Ichthyology • 2013] Arapaima leptosoma • A New Species of Arapaima (Osteoglossomorpha: Osteoglossidae) from the Solimões River, Amazonas State, Brazil

Arapaima leptosoma Stewart, 2013

A new species of Arapaima has been discovered from the central Amazon of Brazil. This new taxon is readily distinguished from all other Arapaima by the following three characters: 1) dorsalmost lateralis sensory cavity on preopercle extremely slender (vs. broadly oval or nearly rectangular in other nominal taxa); 2) ventrolateral margin of head where third infraorbital meets anterior limb of preopercle strongly angled such that ventral surface of head is almost flat (vs. ventrolateral margin of head relatively rounded); and 3) anterior third of dorsal-fin base covered with an enlarged, thickened sheath that hides anterior dorsal-fin rays when adpressed (vs. no thickened sheath on anterior base of dorsal fin and anterior dorsal-fin rays visible when adpressed). Distinguished from all other Arapaima except A. agassizii by having extremely long fourth infraorbital. Distinguished from A. arapaima and all other examined non-type specimens by notably slender body (the holotypes of A. gigas, A. mapae, and A. agassizii also have slender bodies). Further distinguished from A. mapae and A. agassizii by having relatively deep caudal peduncle (6.0% SL, vs. 4.0% in latter two taxa), and from A. gigas by having dentary teeth in a single row (vs. dentary teeth in 2–2.5 irregular rows). This species was collected near the confluence of the Solimões and Purus rivers in Amazonas State, Brazil. It is the first new species of Arapaima to be described since 1847, and comparisons with Arapaima from Mamirauá Reserve demonstrate that there are at least two species of Arapaima present in Amazonas State.

http://facebook.com/photo.php?fbid=646049345415866

Arapaima gigas (Shinz, in Cuvier, 1822)  

Arapaima mapae (Valenciennes, in Cuvier and Valenciennes, 1847)  

Arapaima arapaima (Valenciennes, in Cuvier and Valenciennes, 1847)  

Arapaima agassizii (Valenciennes, in Cuvier and Valenciennes, 1847)  

Arapaima leptosoma Stewart, 2013  

http://facebook.com/photo.php?fbid=10151912146064672

Donald J. Stewart. 2013. A New Species of Arapaima (Osteoglossomorpha: Osteoglossidae) from the Solimões River, Amazonas State, Brazil. Copeia. 2013(3); 470-476.
 http://www.asihcopeiaonline.org/doi/abs/10.1643/CI-12-017

[Ichthyology • 2013] Re-description of Arapaima agassizii (Valenciennes), a Rare Fish from Brazil (Osteoglossomorpha: Osteoglossidae)

The bony-tongue fish genus Arapaima Müller has been considered monotypic since 1868, with A. gigas being the only recognized species. Review of species-level taxonomy of Arapaima has revealed that Arapaima agassizii Valenciennes (in Cuvier and Valenciennes, 1847) should be considered a valid species. The holotype was destroyed in World War II, but the species can be recognized based on the original description, which included detailed osteological illustrations. At least nine characters distinguish it from all other Arapaima: 1) dentary teeth 44 (counted on one ramus only, vs. 21–37 in other Arapaima); 2) maxillary teeth 43 (vs. 21–38 in other Arapaima); 3) orbit diameter 1.5% standard length (SL, vs. 1.5–2.8, relatively larger in all other Arapaima at similar SL); 4) interorbital width 4.1% SL (vs. 5.3–6.5 in other Arapaima); 5) parietals with pronounced posterior projections that are pointed and curve slightly toward midline (vs. absent in other Arapaima); 6) caudal fin widely separated from dorsal and anal fins by long caudal peduncle, 9.7% SL (vs. much shorter peduncle, 3.2–5.5 in others); 7) anal fin with only 26 rays (vs. 30–40 in others), with distinctly shorter basal length than dorsal-fin base; 8) dorsal and anal fins extremely low in profile; dorsal-fin base divided by longest dorsal ray about 7 (vs. 3.1–5.5 in others); and 9) first pectoral-fin ray with proximal tip similar in form to subsequent pectoral-fin rays (vs. first pectoral-fin ray noticeably enlarged relative to subsequent rays). Arapaima agassizii still is known only from the holotype, which was collected in 1817–20 somewhere in lowlands of the Brazilian Amazon. It thus is important to locate this taxon to determine its distribution and conservation status.

http://facebook.com/photo.php?fbid=10151518889899672

Stewart, D.J. 2013. Re-description of Arapaima agassizii (Valenciennes), a Rare Fish from Brazil (Osteoglossomorpha: Osteoglossidae). Copeia. 2013 (1) : 38-51.

http://www.bioone.org/doi/abs/10.1643/CI-12-013

[Ichthyology • 2012] ปลาตะพัดสีนาก | Scleropages inscriptus | Inscribed Asian Arowana • a new fish species from the Tananthayi or Tenasserim River basin, Malay Peninsula of Myanmar (Osteoglossidae: Osteoglossiformes)

Abstract

Scleropages inscriptus, a new species of bony-tongue fishes, is described from the Tenasserim or Tananthayi River basin on the Indian Ocean coast of peninsular Myanmar. It differs from the previously known Southeast Asian and Australian members of the genus in having the bones of the circumorbital and opercular series and all or most of the scales on the sides of the body densely covered with complex maze-like markings. In morphology and in meristic and morphometric characters it is closer to the other Asian species of Scleropages, S. formosus, than to S. leichhardti or S. jardinii, the two species currently recognized from the Australian Region; it is therefore referred to the subgenus Delsmania Fowler 1934 (type species S. formosus).

Tyson R. Roberts 2012. Scleropages inscriptus, a new fish species from the Tananthayi or Tenasserim River basin, Malay Peninsula of Myanmar (Osteoglossidae: Osteoglossiformes) . Aqua, International Journal of ichthyology. 18 (2): 113–118.

http://www.aqua-aquapress.com/index.php?page=shop.product_details&flypage=flypage.tpl&product_id=523&category_id=115&vmcchk=1&option=com_virtuemart&Itemid=1

http://www.aquaterraria.com/en/monster-fish/4552-new-species-of-asian-arowana.html

http://www.practicalfishkeeping.co.uk/content.php?sid=5049

http://www.arowanavalley.com/p/types-of-asian-arowana.html