Ralf Britz

Senckenberg Natural History Collections Dresden · Museum of Zoology

A comparison of the recent description of Chelonodontops bengalensis Habib, Neogi, Og, Lee & Kim 2018 with that of Tetrodon patoca Hamilton 1822 reveals that the former is a junior synonym of the latter. Chelonodon patoca appears to be restricted in its distribution to coastal brackish waters at the mouth of the Ganges/Brahmaputra/Meghna system in...

The miniature fish genus Priocharax currently comprises seven valid species: P. ariel, P. britzi, P. marupiara, P. nanus, P. pygmaeus, P. toledopizae and P. varii. Except for P. ariel and P. pygmaeus, all the species are endemic to Brazil. Priocharax is characterized by several paedomorphic features such as reductions in the laterosensory system, n...

We present a genome assembly from an individual Danionella dracula (the Dracula fish; Chordata; Actinopterygii; Cypriniformes; Danionidae; Danioninae). The genome sequence is 665.21 megabases in span. This is a scaffold-level assembly, with a scaffold N50 of 10.29 Mb.

Motion is the basis of nearly all animal behavior. Evolution has led to some extraordinary specializations of propulsion mechanisms among invertebrates, including the mandibles of the dracula ant and the claw of the pistol shrimp. In contrast, vertebrate skeletal movement is considered to be limited by the speed of muscle, saturating around 250 Hz....

We describe four new species of Channa from Myanmar, all members of the Gachua group. Channa rakhinica, new species, is a species endemic to west-flowing streams on the western slope of the Rakhine Yoma in Rakhine State; C. rubora, new species, occurs in mountain streams south of Mogaung, Kachin State; C. coccinea, new species, co-occurs with C. bu...

Homology is the foundation of any comparative evolutionary study, and as structures previously considered homologous are found to be convergent, and vice versa, terminology needs to be changed to reflect homology. The dorsal-and pectoral fin-spines of catfishes (order Siluriformes) are morphologically diverse and ornamentations adorning the anterio...

Larval attachment organs (LAOs) are unicellular or multicellular organs that enable the larvae of many actinopterygian fishes to adhere to a substrate before yolk‐sac absorption and the free‐swimming stage. Bowfins (Amiiformes) exhibit a sizable LAO on the snout, which was first described in the late 19th and early 20th centuries. In this study, we...

Two new miniature tetra species of the Neotropical characid genus Priocharax Weitzman and Vari, 1987 are described, raising the known species diversity to seven. Both species occur in the Rio Juruá system, Cruzeiro do Sul municipality, Acre State, Brazil. Priocharax toledopizae sp. nov. occurs in streams flowing to the lower Rio Moa, a tributary of...

The lateritic aquifers of the southern Indian state of Kerala harbour a unique assemblage of enigmatic stygobitic fishes which are encountered very rarely, only when they surface during the digging and cleaning of homestead wells. Here, we focus on one of the most unusual members of this group, the catfish Horaglanis, a genus of rarely-collected, t...

Citation: Britz R, Mattox GMT, Conway KW (2023) The quadrate-metapterygoid fenestra of otophysan fishes, its development and homology. Abstract We compare the ontogeny of the hyopalatine arch in representatives of the Otophysi to shed light on the homology of the so-called quadrate-metapterygoid fenestra, QMF. Described initially as a character of...

A new species of swamp eel, Ophichthys terricolus, is described from Assam, India. The new species closely resembles the common Ophichthys cuchia but differs from this species by having fewer abdominal vertebrae (79-80 vs. 95-100), a longer preanal and shorter postanal region, and a wider and higher posterior part of the body.

We studied in detail the head and shoulder girdle skeleton and vertebral column of the holotype of the Mexican endemic swamp eel Ophisternon infernale. This exclusively subterranean species lives in waters inside lime stone caves in Yucatán. Its skeleton shows a number of putative plesiomorphic characters in relation to those of Oph ichthys, Raktha...

Ocean sunfishes of the family Molidae are large oceanic fishes in temperate and tropical seas. In the last revision of the family Molidae, Fraser-Brunner (1951) recognized two species of ocean sunfishes in the genus Mola Koelreuter, 1766: M. mola (Linnaeus, 1758) and M. ramsayi (Giglioli, 1883). Molecular data later confirmed the presence of more t...

In this brief communication, we use CT-scans of a paratype of Priocharax ariel to complement previous osteological information. These new anatomical observations will aid ongoing taxonomic studies of Priocharax.

Dario tigris, new species, is described from mountain streams south of Mogaung, in the Ayeyarwaddy River basin, Myanmar. It differs from congeneric species by its unique colour pattern, which consists of a series of eight straight vertical bars, the first two of which in males are ash-grey and the subsequent six are orange-red in life, combined wit...

The provocative study by Yamahira et al. hypothesizes that one species,Oryzias setnai, endemic to coastal areas of west-flowing streams of the Western Ghats, is the sister species of all other ricefishes and that it diverged in the late Mesozoic. They conclude India is the centre of origin of ricefishes, the ancestrallineage of which subsequently d...

Diversity and distribution of dragon snakeheads of the family Aenigmachannidae, and the identity of Aenigmachanna mahabali

Locomotion exists in diverse forms in nature; however, little is known about how closely related species with similar neuronal circuitry can evolve different navigational strategies to explore their environments. Here, we investigate this question by comparing divergent swimming pattern in larval Danionella cerebrum (DC) and zebrafish (ZF). We show...

The eyes of teleostean fishes typically exhibit two ossifications, the anterior and posterior sclerotics, both associated with the scleral cartilage. The West African Denticle herring Denticeps clupeoides has three scleral ossifications, including the typical two associated with the scleral cartilage (anterior and posterior sclerotic) and a third o...

Based on recently collected material, we redescribe the poorly known synbranchid species Ophichthys fossorius. This highly fossorial species is known from different localities in Kerala, Peninsular India. It can be distinguished from its congeners by its vertebral count of 73-78 precaudal + 52-58 caudal = 126-132 total vertebrae.

The four described species of Danionella are tiny, transparent fishes that mature at sizes between 10–15 mm, and represent some of the most extreme cases of vertebrate progenesis known to date. The miniature adult size and larval appearance of Danionella, combined with a diverse behavioral repertoire linked to sound production by males, have establ...

Groundwater depletion is a significant global issue, but its impact on the often-enigmatic subterranean biodiversity and its conservation remains poorly understood. In the Western Ghats biodiversity hotspot of India, poor governance of groundwater resources is threatening its evolutionarily distinct subterranean freshwater fauna, some taxa of which...

Larval attachment organs (LAOs) are unicellular or multicellular organs that allow larvae to adhere to a substrate before yolk‐sac absorption and the free‐swimming stage. This study documents the LAO of tropical gar, Atractosteus tropicus, using a combination of scanning electron microscopy and light microscopy. It is shown that the LAO of A. tropi...

Originally described as Muraena alba by the Russian ichthyologist Basilius Zuiew (1793) [Vasilij Fyodorovich Zuev’], the name Monopterus albus has long been used for a species of swamp eel (Synbranchidae) with a reportedly widespread occurrence in Asia (Rosen & Greenwood 1976, Kottelat 2013). In recent years molecular studies have shown that Monopt...

Locomotion exists in diverse forms in nature and is adapted to the environmental constraints of each species1. However, little is known about how closely related species with similar neuronal circuitry can evolve different navigational strategies to explore their environments. We established a powerful approach in comparative neuroethology to inves...

We provide a detailed description of the head and shoulder girdle osteology of the holotype of the synbranchid 'Monopterus' roseni Bailey & Gans. Collected from a well in Kerala, this subterranean synbranchid shows a number of unique and highly derived characters in the gill arch skeleton. In 'Monopterus'roseni, basibranchial 2 does not articulate...

Background Species of Danionella rank among the smallest of all vertebrates and their miniature size is correlated with an extreme case of progenesis, resulting in tiny, transparent sexually mature individuals. Progenesis has affected the entire skeleton of Danionella, in which 60 skeletal elements are absent, including some of the skull roofing bo...

Pronounced organism-wide morphological stasis in evolution has resulted in taxa with unusually high numbers of primitive characters. These ‘living fossils’ hold a prominent role for our understanding of the diversification of the group in question. Here we provide the first detailed osteological analysis of Aenigmachanna gollum based on high-resolu...

A new miniature species of the freshwater fish genus Priocharax is described from the Rio Jamari, Rio Madeira drainage, Amazon basin. Priocharax varii sp. n. is the fourth species currently recognized in the genus and shares with the other three the presence of a conspicuous larval pectoral fin in adults, a fully toothed maxilla, a triangular pseud...

As the type species of the genus Channa, the identity of the pelvic-finless snakehead Channa orientalis Bloch is important to channid systematics. Although this name has been attached to a Sri Lankan species for the past 160 years, its vaguely specified type locality, ‘India Orientali’, has long cast doubt as to its origin. Here, based on a collect...

The dwarf snakehead Channa gachua (Hamilton, 1822) (type locality Bengal) has been reported from a vast range, from Iran to Taiwan, and northern India to Sri Lanka. Here, adopting an integrative taxonomic approach, we show that the Sri Lankan snakehead previously referred to as C. gachua is in fact a distinct species, for which the name C. kelaarti...

Mouthbrooding or oral incubation, the retention of early developmental stages inside of the mouth for an extended period of time, has evolved multiple times in bony fishes1,2. Though uncommon, this form of parental care has been documented and well-studied in several groups of freshwater fishes but is also known to occur in a small number of marine...

Mouthbrooding or oral incubation, the retention of early developmental stages inside of the mouth for an extended period of time, has evolved multiple times in bony fishes1,2. Though uncommon, this form of parental care has been documented and well-studied in several groups of freshwater fishes but is also known to occur in a small number of marine...

The taxonomic status of the large snakeheads of the Channa marulius group that occur in Sri Lanka is reviewed and clarified. Two species are recognized from the island, based on both morphological and molecular (cytochrome c oxidase subunit 1: cox1) differentiation: C. marulius Hamilton from the northern dry zone and C. ara Deraniyagala from the mi...

The endemic Sri Lankan synbranchid 'Monopterus' desilvai is redescribed based on additional material. In life, individuals have a maroon background colour with numerous dark brown blotches. They breathe air, which is stored in paired suprabranchial pouches. The head skeleton of M. desilvai is described in detail. This species shares with M. cuchia,...

We feel that two of the biggest challenges taxonomy is facing are the same as during the last twenty-five years since the biodiversity crisis moved to the center of attention: (1) inadequate funding combined with (2) the lack of succession planning, training and recruitment into permanent positions of competent taxonomists. Another significant issu...

Channa rara, new species, is described from the Jagbudi River in Maharashtra, India. It belongs to the Gachua group and differs from all its members by the possession of one or more ocelli in the posterior part of the dorsal fin in adults (vs. ocelli absent or 1, rarely 2–3 ocelli in juveniles only). It is further distinguished from most species of...

A unique, new species of eel loach, Pangio bhujia, is described from Kerala, India. It is the first species of Pangio to be described from subterranean waters. It possesses several unusual characters including absence of both dorsal and pelvic fins, the presence of only 3 pectoral-fin rays, 6 anal-fin rays and a unique count of 38 precaudal + 24 ca...

The collision of the Indian and Eurasian landmasses in the Cenozoic was a decisive factor in shaping biodiversity patterns in Southern and Southeastern Asia. While most studies thus far have focused on the biotic interchange between India and Eurasia and evolutionary diversification on or around the Tibetan Plateau, little attention has been paid t...

The species-level taxonomy of all extant members of the family Polypteridae is revised. Two genera are recognised: Polypterus and the monotypic Erpetoichthys. Thirteen species of Polypterus are regarded as valid: P. bichir (type species), P. ansorgii, P. congicus, P. delhezi, P. endlicherii, P. mokelembembe, P. ornatipinnis, P. palmas, P. polli, P....

Teleost fishes develop remarkable varieties of skin ornaments. The developmental basis of these structures is poorly understood. The order Tetraodontiformes includes diverse fishes such as the ocean sunfishes, triggerfishes, and pufferfishes, which exhibit a vast assortment of scale derivatives. Pufferfishes possess some of the most extreme scale d...

Aenigmachanna gollum, new genus and species, is described from Kerala, South India. It is the first subterranean species of the family Channidae. It has numerous derived and unique characters, separating it from both the Asian Channa Scopoli and the African Parachanna Teugels & Daget. Uniquely among channids, A. gollum has a very slender (maximum b...

Channa auroflammea is a new freshwater fish species of the Marulius group from the Mekong River system. Previously reported as C. marulius, C. cf. marulius, or C. aff. marulius, C. auroflammea is readily distinguished from C. marulius and other members of the Marulius group by a different colour pattern, and a DNA barcode sequence at least 6.5% div...

Attachment organs are predominantly known from larval stages of freshwater fishes and are used to attach to various substrates. They are functional upon hatching for a few days and usually disappear when the yolk sac is resorbed and the larvae are free swimming in the water column. Attachment organs are reported for the first time in a representati...

The characteristic and morphologically variable pectoral‐fin spine of catfishes (order Siluriformes) has been well‐investigated based on later developmental stages (juveniles and adults) but information on the earliest life stages are lacking. Here, we document the ontogeny of pectoral‐fin spines in four siluroid (Ictalurus punctatus, Noturus gyrin...

The "bullseye" or "cobra" snakehead is a large, predatory freshwater fish of South Asian origin. Until recently, only one bullseye species has been recognised, Channa marulius, but new studies on the 'Marulius group' have revealed that there are at least four species with different native ranges in rivers of mainland South Asia, as well as Channa m...

Channa aurolineata is a valid species of the Marulius group. Previously treated as a synonym of C. marulius, C. aurolineata is readily distinguished from C. marulius by a different colour pattern, in which a conspicuous white posterior margin is present on the black scales that form the dark lateral blotches in larger juveniles and adults (vs. scal...

Egg structure and larval development of Paedocypris carbunculus are described based on 15 specimens (2 eggs, 13 larvae) obtained from captive rearing. The adhesive eggs, which are laid on the underside of plant leaves, are 450-500 μm in diameter with a smooth surface. Eggs hatch ca. 36 hours after egg deposition, and newly hatched larvae measure ca...

Teleost fishes develop a huge variety of skin ornaments. How these diverse skin structures develop in fishes is unknown. The teleost fish order Tetraodontiformes includes some of the most unusual fishes such as the ocean sunfish, triggerfish and pufferfish, and they all can develop a vast assortment of scale derivatives that cover their bodies. Puf...

Dario neela, is described from a small tributary stream of the Kabini River in northern Kerala, India. It can be distinguished from congeners by the male colouration in life, which shows wide rims of iridescent blue in all median fins and the pelvic fin. It is further distinguished from all species of Dario, except D. urops by the number of abdomin...

The world’s smallest fishes belong to the genus Paedocypris. These miniature fishes are endemic to an extreme habitat: the peat swamp forests in Southeast Asia, characterized by highly acidic blackwater. This threatened habitat is home to a large array of fishes, including a number of miniaturized but also developmentally truncated species. Especia...

In his work on the fishes of the Andaman Islands, Francis Day (1870) collected large-sized specimens of Aplocheilus from the south Andamans. Despite differences in the size and dorsal-fin ray counts, Day refrained from recognising the Andaman Aplocheilus as a distinct species and considered it as Aplocheilus panchax, a species distributed in the Ga...

Snakehead fishes of the family Channidae are predatory freshwater teleosts from Africa and Asia comprising 38 valid species. Snakeheads are important food fishes (aquaculture, live food trade) and have been introduced widely with several species becoming highly invasive. A channid barcode library was recently assembled by Serrao and co-workers to b...

50% Majority rule consensus tree of the neighbour joining tree based on HKY distances. Bootstrap values from 1000 pseudoreplicates are shown. (EPS)

Snakehead chronogram from the BEAST analysis using a coalescence prior. Species delimitations based on BIN, GMYC single, GMYC multiple, and PTP thresholds are indicated by black bars. Misidentified and incomplete identified specimens are indicated with a red dot. (EPS)

Neigbour joining tree of Parachanna including additional sequences. The lineage corresponding to the new species Pa. sp. DRCongo is highlighted in light red. (PDF)

Neigbour joining tree based on HKY distance. Misidentified and incomplete identified specimens are indicated with a red dot. (EPS)

Maximum likelihood tree of the 423 taxa data set that only included unique haplotypes. Bootstrap values from 1000 pseudoreplicates are shown. (PDF)

Table of specimens, GenBank accession numbers, BOLD identification, BIN assignment and locality information. (XLSX)

Result of the bGMYC analysis showing sequence-by-sequence distribution of posterior probabilities. The coloured table is a matrix with the probabilities of sequences to be conspecific, ranking from yellow to red: the highest to the lowest values. The timetree corresponds to the consensus tree from BEAST analysis. (EPS)

Hamilton (1822) described Cyprinus mosal, now assigned to the genus Tor, from the ‘Kosi’, a tributary of the Ganges. The fact that two Gangetic tributaries with the name Kosi exist, has resulted in confusion in the Indian ichthyological literature and beyond regarding the type locality of Hamilton’s T. mosal. A critical review of Hamilton’s treatis...

The identity of Mastaceinbelus dayi is discussed and a lectotype is designated. Mastaceinbelus alboguttatus is a senior synonym of M. dayi and the valid name for this species. It grows up to at least 700 mm SL and is known from its type locality, the Sittang, large parts of the Chindwin and from the Ayeyarwaddy around Mandalay.

An investigation integrating morphological and molecular data to address the taxonomic status of Indian Channa marulius-like fishes reveals the presence of two species within Indian Rivers. As a consequence, Channa pseudomarulius is resurrected as a valid species and removed from the synonymy of C. marulius. Channa pseudomarulius appears to be rest...

Hox genes play a fundamental role in regulating the embryonic development of all animals. Manipulation of these transcription factors in model organisms has unraveled key aspects of evolution, like the transition from fin to limb. However, by virtue of their fundamental role and pleiotropic effects, simultaneous knockouts of several of these genes...

Significance Teleost fishes have evolved a wonderful array of diverse dentitions. The highly derived order Tetraodontiformes exhibits the most unique dental forms among teleosts. The novel beak-like dentition of the pufferfish develops through a drastic shift in dental morphology during ontogeny. A simple first-generation tooth set is followed by t...

Miniaturization, the evolution of extremely small adult body size, is widespread amongst animals and commonly associated with novel ecological, physiological, and morphological attributes. The phenotypes of miniaturized taxa are noteworthy because they combine reductions and structural simplifications with novel traits not developed in their larger...

A new species of torrent catfish, Amblyceps accari, is described from the central region of the Western Ghats of India. The new species differs from all its congeners by having 12 branched anal-fin rays (vs. 7–10 in other Amblyceps, rarely 11 in A. tuberculatum). It differs further from all other species of the genus except A. murraystuarti and A....

Pillaiabrachia siniae, now genus and new species, is described from a small pool near Mogaung in Kachin state, northern Myanmar. It can be distinguished from all other chaudhuriids by the complete lack of pectoral fins and ribs, and by the combination of 37 + 33 vertebrae, 31 dorsal-, 33 anal-, and six caudal fin rays.

We provide a detailed account of the osteology of the miniature Asian freshwater cyprinid fish Danionella dracula. The skeleton of D. dracula shows a high degree of developmental truncation when compared to most other cyprinids, including its close relative the zebrafish Danio rerio. Sixty-one bones, parts thereof or cartilages present in most othe...

Establishing phylogenetic relationships of miniature fishes is challenging in taxa with developmental truncation. Within the Characiformes, developmental truncation appears to be relatively rare, with the Neotropical genus Priocharax being an example. Priocharax includes three miniature species among the smallest of the order and has been hypothesi...

The Asian (nandid) and Afro-Neotropical (polycentrid) leaffishes represent two superficially similar, but historically poorly diagnosed families – a situation resulting in a convoluted systematic history. Here, and including for the first time in a molecular study all leaffish genera, we generate a hypothesis of the phylogenetic history of both gro...

Danio feegradei Hora is redescribed based on recently collected specimens from small coastal streams on the western slope of the Rakhine Yoma, ranging from the Thade River drainage southward to slightly north of Kyeintali. Danio absconditus, new species, is described from the Kyeintali Chaung and small coastal streams near Gwa, south of the range o...

Psilorhynchus olliei, new species, is described from the Irrawaddy drainage, Kachin State, eastern Myanmar. It is distinguished from other members of the P. balitora species group by a combination of characters, including unique features of body and fin coloration and lateral-line scale, fin-ray, vertebrae, and cephalic lateral-line canal pore coun...

Dario huli, new species, is described from a small tributary stream of the Tunga River in southern Karnataka, India. It can be distinguished from all its congeners except D. urops by the presence of a conspicuous black caudal-fin blotch and by anterior dorsal-fin lappets in males not being produced beyond fin spines. It is readily distinguished fro...