Marcelo Melo

• PhD
• Professor at University of São Paulo

The deep sea environment is the largest environment and host some of the most extreme ecosystems on Earth, therefore, possessing a large and unique fish diversity that encompasses about 15% of all known species. Our knowledge about these fishes is still very limited in many biological fields basically due to the complexity to obtain specimens for r...

Holtbyrnia anomala is a bathypelagic platytroctid widely distributed in the Atlantic Ocean. In this contribution, we report, for the first time, the occurrence of this species in the tropical southwest Atlantic. A single specimen was collected in 2000 on the continental slope off Rio de Janeiro, Brazil, at an average depth of 1158 m. This report al...

Sciadonus alphacrucis Melo, Gomes, Møller & Nielsen, 2022 is a rare deep‐sea species, previously known from only two specimens collected off São Paulo State, southeastern Brazil, in the western South Atlantic. Herein, we report a new specimen of S. alphacrucis collected on the continental slope off Santa Catarina State, southern Brazil, thereby ext...

The limited temporal completeness and taxonomic accuracy of species lists, made available in a traditional manner in scientific publications, has always represented a problem. These lists are invariably limited to a few taxonomic groups and do not represent up-to-date knowledge of all species and classification. In this context, the B Brazilian meg...

The family Polymixiidae is an ancient group of acanthomorph fish, often regarded as living fossils. Currently, there are 11 valid species allocated in the genus Polymixia, and commonly known as beardfish. All species are benthopelagic and can be found at depths between 80 and 800 meters, in the Atlantic, Indian, and Pacific oceans. Traditionally, o...

The presence of marine litter in the deep ocean (>200 m depth) may represent an invisible threat that has been neglected due to the scarcity of data. Herein, we provide the first report of persistent marine litter on the Southwestern Atlantic continental slope. Marine litter was collected onboard the Brazilian R/V Alpha Crucis, using bottom trawlin...

A new species of the rare, deep-sea genus Sciadonus Garman, 1899 (Bythitidae) is described based on two specimens obtained by the Brazilian R/V Alpha Crucis on the continental slope off São Paulo State, Southeastern Brazil, western South Atlantic. It differs from its congeners by the combination of the following characters: body pale lacking dark p...

The family Myrocongridae comprises some of the rarest and least known benthopelagic eel species. It is composed of a single genus, Myroconger Günther, 1870, and five valid species: M. compressus Günther, 1870, from the Atlantic Ocean; M. gracilis Castle, 1991, M. prolixus Castle & Béarez, 1995, and M. nigrodentatus Castle & Béarez, 1995, from the P...

A new species of Characidium is described from the Cerrado biome, in Brasília, Distrito Federal, Central Brazil. The new species can be readily diagnosed by the presence of two or three longitudinal rows of dots along the body sides, absence of bars, by the short pectoral fin, which does not reach the vertical through the dorsal fin origin. Additio...

A new species of Characidium is described from the tributaries of the rio Tocantinzinho, rio Tocantins basin, located in the southern portion of the Chapada dos Veadeiros, at about 1,200 meters of elevation, Goiás, Brazil. The new species can be diagnosed by an unusual combination of two apomorphic features present in distinct clades of Characidium...

The deep sea is the largest and one of the most extreme environments on Earth. It is estimated that 10–15% of all fish species are dwelling in the deep sea, most of which have unique morphological and physiological adaptations. Biological expeditions to sample the deep ocean off Brazil started with the British HMS Challenger Expedition (1872–1876),...

Characidium pumarinri n. sp. is described from the affluents of Río Huallaga, a tributary of Río Marañón that drains the eastern slopes of the Andes, in the Peruvian Amazon. The new species has a deep body (24–31% in LS), 11–17 well‐marked dark bars and remarkable sexual dimorphism related to colour pattern, in which males have darker anal, dorsal,...

A new species of Characidium is described from headwater tributaries of the upper rio Guaporé, Rio Madeira basin, Mato Grosso state, Brazil. The new species can be diagnosed from all congeners, except Characidium summus, for lacking the preorbital and postorbital stripes. It can be diagnosed from the latter species by having 12 circumpeduncular sca...

A new species of Characidium Reinhardt, 1867 endemic to tributaries of the upper rio Paraguaçu in the Chapada Diamantina, Bahia, Brazil, is described. The new species can be distinguished from its congeners except C. bahiense, C. bimaculatum, C. laterale, C. nana, C. nupelia, and C. xavante, by having a conspicuous peduncular blotch in addition to...

A new species of Dysalotus (family Chiasmodontidae) known only from off the Hawaiian archipelago is described here as Dysalotus pouliulii sp. nov. It differs from all other species of Dysalotus in having a greater number of teeth on the premaxilla (151–198 v . 60–138) and dentary (136–199 v. 76–132) and in a shorter upper jaw [51·9–54·9% of head le...

A new species of Characidium is described based on specimens obtained from the highland streams of the Serra do Mar, Atlantic Forest Biome, in Paraná State, Southern Brazil. The new species is possibly a member member of the C. lauroi group, which is diagnosed by having the isthmus unscaled, bars poorly marked, and spots on sides of body, and is co...

Urophycis Gill 1864 is a genus of demersal fish composed by eight valid species with anti-tropical distributions in the western Atlantic. Only two species occur in the South Atlantic: U. brasiliensis (Kaup 1858) and U. mystacea Miranda Ribeiro 1903. These species have similar ranges from southeastern Brazil to northern Argentina, but U. brasiliensi...

The taxonomic status of three species of eels described from leptocephali larvae in 1960, is revised and elucidated: Leptocephalus anaelisae Tommasi, 1960, a member of Moringuidae, is confirmed as a junior synonym of Neoconger mucronatus Girard, 1858; Leptocephalus juliae Tommasi, 1960, a Muraenidae, is confirmed as a junior synonym of Uropterygius...

The ongoing fiscal and political crisis in Brazil has already caused deep cuts to science and education (“Fiscal crisis has Brazilian scientists scrambling,” H. Escobar, In Depth, 28 August, p. [909][1]), and now the environment is in the crosshairs. On 2 October, the Federal Government

We herein describe Characidium satoi, new species, only known from its type locality at Rio Curral das Éguas, a small tributary of Rio Abaeté, in the Rio São Francisco basin, Brazil. It can be distinguished from its congeners by the following characteristics: area between the pelvic fin and the origin of anal fin moderate to strongly convex in late...

Assemblages of demersal bony fishes on the slope of the eastern Brazilian coast. Demersal and benthopelagic teleost fishes from central (eastern) Brazilian coast were sampled between 195-2.137 m. The material examined was obtained during a deep exploratory-fishing cruise along the coasts of Bahia, Espírito Santo and north of Rio de Janeiro state (f...

Background. Chiasmodon harteli Melo, 2009 is a rarely captured deepwater fish. Even though the taxonomy of this genus is fairly well resolved, very little is known about the biology of individual Chiasmodon species. The objective of the presently reported study was to supplement new knowledge on C. harteli. Materials and methods. A single female sp...

Pseudoscopelus Lütken is a genus of meso- and bathypelagic fishes with a worldwide distribution. The genus is the most diversified within the family Chiasmodontidae, containing 16 valid species, three of which are described herein as new: Pseudoscopelus scriptus Lütken, from the western Central and North Atlantic; P. sagamianus Tanaka, from the Eas...

The genus Kali is a member of the deep-sea fish family Chiasmodontidae with seven valid species. A taxonomic revision of Kali was recently conducted by Melo (2008), which included the description of two new species: K. colubrina and K. falx. I was unaware that parallel to that revision, Prokofiev (2008) was describing K. caribbaea. Both publication...

New collections made by the French research vessel Thalassa and the Brazilian Astro Garoupa on the Brazilian continental slope, between 11° and 23° S revealed a great diversity of deep-sea gadiforms obtained between 200 and 2270 m. Of the 34 species collected, 13 (38%) are being reported for the first time in the western South Atlantic and one may...

New collections made by the French research vessel Thalassa and the Brazilian Astro Garoupa on the Brazilian continental slope, between 11° and 23° S revealed a great diversity of deep-sea gadiforms obtained between 200 and 2270 m. Of the 34 species collected, 13 (38%) are being reported for the first time in the western South Atlantic and one may...

A review of the deep-sea anguilliform and saccopharyngiform eels collected by the French R/Vs Marion Dufresne (1987), Thalassa (1999, 2000), and the Brazilian Astro Garoupa (2003) revealed a great diversity of these groups on the Brazilian continental slope (11-23 o S, 19-40 o W), in the depth range of 233 to 3450 m. Of the 33 species collected, 13...

A review of the deep-sea anguilliform and saccopharyngiform eels collected by the French R/Vs Marion Dufresne (1987), Thalassa (1999, 2000), and the Brazilian Astro Garoupa (2003) revealed a great diversity of these groups on the Brazilian continental slope (11–23 o S, 19–40 o W), in the depth range of 233 to 3450 m. Of the 33 species collected, 13...

Chiasmodon Is a genus of meso- and bathypelagic fishes, commonly known as swallowers. The genus has a wide distribution In the Atlantic, Pacific, Indian, and Southern Oceans. Five species previously described are considered valid and two are described as new: C. niger, from tropical North Atlantic, including the Gulf of Mexico and Caribbean; C. sub...

Hemiancistrus cerrado is described from the tributaries of rio Araguaia, rio Tocantins basin. Hemiancistrus cerrado has external similarities with H. megalopteryx and H. punctulatus from coastal streams of southern Brazil, and can be distinguished by having a larger internarial width, 15.9-21.1% of head length (vs. 11.2-14.0% in H. megalopteryx and...

Kali Lloyd is a very distinctive group of bathypelagic fishes with fragile bones in the cranium and recurved teeth, which are remarkably enlarged in some species. The genus has a worldwide distribution, being found in the subtropical to equatorial regions of the Atlantic, Indian, and Pacific; one species is also found in the Southern Ocean. In this...

Kali Lloyd is a very distinctive group of bathypelagic fishes with fragile bones in the cranium and recurved teeth, which are remarkably enlarged in some species. The genus has a worldwide distribution, being found in the subtropical to equatorial regions of the Atlantic, Indian, and Pacific; one species is also found in the Southern Ocean. In this...

Two new species of the deep-sea fish genus Pseudoscopelus are described, P. lavenbergi from the eastern Pacific, and P. bothrorrhinos from the western Pacific and Indian Oceans. A new diagnosis for Pseudoscopelus based on two synapomorphies is proposed: the dorsal margin of the orbit is formed by infraorbital 6; the last pore of the infraorbital ca...

Two new species of the deep-sea fish genus Pseudoscopelus are described, P. lavenbergi from the eastern Pacific, and P. bothrorrhinos from the western Pacific and Indian Oceans. A new diagnosis for Pseudoscopelus based on two synapomorphies is proposed: the dorsal margin of the orbit is formed by infraorbital 6; the last pore of the infraorbital ca...

A new synaphobranchid eel from the Brazilian continental slope is described herein as Synaphobranchus calvus. The species is distinguished from its congeners by the absence of scales on the head (vs. head scaled in other species) and its black to brown body with a deep blue belly (vs. body entirely black, gray, or brown in the remaining species). F...

Assemblages of demersal bony fishes on the slope of the eastern Brazilian coast. Demersal and benthopelagic teleost fishes from central (eastern) Brazilian coast were sampled between 195-2.137 m. The material examined was obtained during a deep exploratory-fishing cruise along the coasts of Bahia, Espírito Santo and north of Rio de Janeiro state (f...

A new species of Characidium is described from tributaries of the rio Paranã (Tocantins drainage), in Goiás State, central Brazil. Characidium stigmosum is diagnosed by the presence of dark marks along the sides of the body, which are associated with the vertical bars that occur in most species of Characidium. These marks are vertically oriented el...