A new species of Astyanax Baird & Girard (Characiformes: Characidae) from the Rio Paraguaçu basin,Chapada Diamantina,Bahia, Brazil,with comments on bony hooks on all fins

A new species of Astyanax from the Rio Paraguaçu basin, Bahia, Brazil, is described. This new species is distinguished from its congeners known to occur in Brazilian drainages by the presence of small bony hooks on all fins of mature males. Furthermore, the new species can be diagnosed by its colour pattern, which consists of a unique vertically elongated humeral blotch, a conspicuous dark drop‐shaped horizontal blotch over the caudal peduncle, tapering anteriorly and not extending to the median caudal‐fin rays, and by the absence of a conspicuous broad dark midlateral stripe. The new species differs further by having the greatest body depth just anterior to the dorsal‐fin origin, 32–35 perforated scales in the lateral line and a reduced number of branched anal‐fin rays (16–20). Apparently, the new species does not fit into any species complex of Astyanax. The occurrence of bony hooks on all fins of Astyanax is discussed.     

A new species of Hemigrammus (Characiformes: Characidae) from western Amazon River basin,Colombia

A new species of Hemigrammus is described from the Amazon Basin near Leticia, Departamento Amazonas, Colombia. In common with some congeners and some Hyphessobrycon spp., the new species colour pattern lacks a humeral blotch but has a caudal-peduncle blotch. It can be distinguished from congeners with a similar colour pattern by having: a relatively deep body (30.2%–39.0% L_S), 20–24 branched anal-fin rays, 6–8 perforated scales of the lateral line, anal-fin base without a conspicuous black stripe, 3–5 maxillary teeth, maxillary teeth with 1–3 cusps, a thin longitudinal midlateral line and a well-defined oval shaped caudal blotch, extending from caudal peduncle into the lower caudal-fin rays. Comparisons with congeners and with Hyphessobrycon species sharing the same general colour pattern are presented.     

Poptella fuscata,a new Stethaprionini from the upper Amazon basin,Peru (Characiformes: Characidae)

A new species of Poptella is described from the Río Putumayo, Upper Río Amazon basin, Peru. The new species is distinguished from congeners by having a dense field of dark chromatophores homogeneously spread over the posterior half of the body, posterior humeral blotch extending to three to four horizontal scale rows below the lateral line, and a higher number of branched dorsal-fin rays. The new species can be readily distinguished from P. paraguayensis by having a comparatively shorter predorsal spine.     

A new species of miniature Characidium (Characiformes: Crenuchidae) from the upper Rio Paraguay basin,Mato Grosso state,Brazil

A new miniature species of Characidium is described from the upper Rio Paraguay basin, Brazil. The new species can be diagnosed from all congeners by the presence of a dark-brown humeral blotch, vertically elongated (spanning 5 to 7 horizontal scale rows), with the shape of an upside-down acute triangle. Additionally, it can be diagnosed by a short lateral line (6 to 8 perforated scales), the absence of a conspicuous peduncular blotch, a lower number of principal caudal-fin rays (14–16) and by absence of the adipose fin. The new species is the smallest species of the genus; the largest specimen was 19.3 mm standard length.     

A new rheophilic South American darter (Crenuchidae: Characidium) from the rio Juruena basin,Brazil, with comments on morphological adaptations to life in fast-flowing waters

Characidium iaquira, a new species from the upper rio Juruena, rio Tapajós basin, Brazil, is described. The new species can be promptly distinguished from all congeners by having a unique v-shaped dark mark lying along the caudal-fin extension, in medium- and large-sized specimens, and a remarkable iridescent green colouration in life. Characidium iaquira is closely related to Characidium crandellii and Characidium declivirostre by sharing unambiguous synapomorphies such as branchiostegal membranes united to each other across the isthmus, a scaleless area extending from the isthmus to the pectoral girdle, and dermal flaps surrounding anterior and posterior naris independent, but touching each other distally. Morphological specializations of the paired fins in the three riffle-dwellers species are discussed, including the wing-like shape, robustness, and inclination of the pectoral fin.     

A new species of Astyanax (Characiformes: Characidae) from Costa Rica and Panama,with a key to the lower Central American species of the genus

Astyanax anai, a new species of characid fish, is described from the Sixaola River basin, eastern Costa Rica–western Panama, Central America. The new species can be distinguished from all other congeners by the following combination of characters: premaxillary teeth 4–5 at the inner series and 4–6 at the outer series; maxillary teeth tricuspid, 2–4; predorsal scale series irregular and incomplete, with an unscaled space behind tip of supraoccipital process and 12–14 scales; lateral line scales 34–39; humeral region with a conspicuous black and rounded to horizontally ovate spot and two diffuse brown and vertically elongate bars (the first through the rounded to horizontally ovate spot, the second 2–4 scales behind the first); body depth 36·6–42·3% of standard length (L_S); midlateral stripe formed by a series of 10–14 anteriorly‐directed dermal herringbone, or chevron‐shaped, marks, most apparent in juveniles and in preserved specimens, extending above the lateral line from the black humeral spot or just behind it (from the second vertical bar) to the caudal peduncle; scale rows from lateral line to base of first dorsal‐fin ray 8–9; scale rows from lateral line to base of pelvic fin 7–8; pre‐anal distance 53·9–61·9% of L_S; total anal‐fin elements 29–33; caudal spot elongated, rhomboid or rectangular, with its anterior margin surpassing the middle of the caudal peduncle, usually reaching the anal‐fin insertion, posteriorly covering 4–7 principal caudal‐fin rays and not extending onto the ventral and dorsal margins of the caudal peduncle, covering 3–5 horizontal scale rows. In order to test the phylogenetic relationships of the new taxon in relation to the other North and Central American species of the genus, a new phylogenetic hypothesis based on a reanalysis of the morphological matrix by Schmitter‐Soto (2016) is proposed. A key to the lower Central American (southern Nicaragua to eastern Panama) species of Astyanax is also provided.     

Moenkhausia andrica (Characiformes: Characidae): a new species from the rio Tapajós basin,Brazil, with minute fin hooklets in females

In this study, a new species of Moenkhausia is described from the upper rio Juruena, rio Tapajós basin, Brazil. It is distinguished from all congeners by the presence of minute bony hooks in all fins of both mature females and males and combination of a prepelvic region flattened, dorsal portion of the humeral blotch extending two scales horizontally and vertically, lateral line with 28–32 scales, five scale series above and below lateral line; circumpeduncular scales 13–14, anal-fin rays 16–19 and dorsal portion of eyes blue in live specimens. The new species is also supported by high divergence in the mitochondrial gene cytochrome c oxidase subunit I (COI). The presence of minute fin bony hooks in both females and males, population variations and late development of the lateral line in Moenkhausia andrica are discussed.     

Sinocyclocheilus zhenfengensis,a new cyprinid species (Pisces: Teleostei) from Guizhou Province,Southwest China

Sinocyclocheilus zhenfengensis sp. nov. is a new species from an underground water environment in a karst cave located in Beipanjiang River of the Pearl River Basin in Shuangrufeng (Double Breasts Hill) Scenic, Etian Village, Zhexiang Township, Zhenfeng County, Guizhou Province, Southwest China. The new species has eyes, its body is completely scaled, an anteriorly directed bulge has formed on the back of its head, and a long pectoral fin exceeds the pelvic fin insertion. The body of the new species is apparently similar to that of S. bicornutus, but differs in scale rows above the lateral line, scale rows below the lateral line, snout length, and eye diameter. Phylogenetic reconstruction of the cytochrome b gene using the maximum parsimony (MP) and Bayesian inference (BI) methods indicates that S. zhenfengensis is closely related to S. bicornutus, S. tianeensis, S. jiuxuensis, and S. altishoulderus; however, it differs in terms of eye size, lateral line scales, scale rows above and below the lateral line.     

A new Hemigrammus from the upper Río Vaupés,Colombia (Characiformes: Characidae), with a discussion on the presence of an enlarged urogenital papilla in the family

Hemigrammus xaveriellus sp. nov. is described from the upper Río Vaupés basin (Amazon basin), Departamento Guaviare, Colombia. It is distinguished from all congeners by the combination of the following characters: presence of a conspicuous, dark, longitudinal midlateral stripe extending along the body; presence of a conspicuous rounded, horizontally elongated humeral blotch anterior to the beginning of the dark midlateral stripe; seven scale rows between the dorsal fin and lateral line (vs. five to six); and five scale rows between the lateral line and pelvic-fin insertion (vs. three to four). The single mature male of He. xaveriellus possessed a well-developed urogenital papilla, an unusual feature among characids. The presence of an enlarged urogenital papilla in the family is discussed, and comments regarding the putative relationships of the new species are presented.     

Hisonotus acuen,a new and phenotypically variable cascudinho (Siluriformes,Loricariidae, Hypoptopomatinae) from the upper rio Xingu basin,Brazil

A new species of Hisonotus is described from the headwaters of the rio Xingu. The new species is distinguished from its congeners by having a functional V-shaped spinelet, odontodes not forming longitudinal aligned rows on the head and trunk, lower counts of the lateral and median series of abdominal figs, presence of a single rostral fig at the tip of the snout, absence of the unpaired figlets at typical adipose fin position, yellowish-tipped teeth, absence of conspicuous dark saddles and stripe on the body and higher number of teeth on the premaxillary and dentary. The new species, Hisonotus acuen, is restricted to headwaters of the rio Xingu basin, and is the first species of the genus Hisonotus described from the rio Xingu basin. Hisonotus acuen is highly variable in aspects of external body proportions, including body depth, snout length, and abdomen length. This variation is partly distributed within and among populations, and is not strongly correlated with body size. PCA of 83 adult specimens from six allopatric populations indicates the presence of continuous variation. Therefore, the available morphological data suggest that the individuals inhabiting the six localities of rio Xingu represent different populations of a single species. Low intraspecific variation in mitochondrial Cytochrome oxidase subunit I (COI) provides corroborative evidence.     

<Emphasis Type="Italic">Sebastapistes taeniophrys</Emphasis> (Fowler 1943): a valid scorpionfish (Scorpaenidae) from the Philippines

The poorly known scorpionfish, Scorpaena taeniophrys, originally described from two specimens from the Philippines, is redescribed as a valid species of Sebastapistes. Sebastapistes taeniophrys differs from all other congeners in having a combination of 15 pectoral-fin rays, 31–33 scale rows in longitudinal series, 11–14 pored lateral-line scales, 3 predorsal scale rows, 12 gill rakers, 3 suborbital spines, absence of coronal spines, lower opercular spine with a median ridge and not covered with scales, ctenoid body scales, several dark transverse bands on ventral surface of mandible, a distinct elongate black blotch distally between the second or third and seventh dorsal-fin spines, and no black blotch on the nape.     

A new endangered species of Megaleporinus (Characiformes: Anostomidae) from the Rio de Contas basin,eastern Brazil

A new species of Megaleporinus is described from the Rio de Contas, a coastal drainage of eastern Brazil, and its phylogenetic relationships are studied using molecular data. The new species is unique among Anostomidae by possessing two exclusive features: an irregular dark longitudinal stripe from supracleithrum to second midlateral blotch and anterior cranial fontanel partially closed. In addition, the new species is diagnosed by having three premaxillary teeth, three dentary teeth, 37 or 38 scales in lateral line, 16 scale rows around caudal peduncle, three dark midlateral blotches on body, and red fins in life. The new species is closely related to M. obtusidens from the São Francisco basin, corroborating previous studies that indicated that the latter represents a species complex as currently defined. The new species exhibits the first rib enlarged in mature males, a feature described for some congeners. The new species is herein considered to be Endangered under the IUCN criteria.     

A new species of trout from the northern drainages of Euphrates River,Turkey (Salmoniformes: Salmonidae)

Salmo fahrettini, a new species, is distributed in the northern tributaries of the Euphrates River. It differs from other Salmo species in adjacent waters by a combination of the following characters: a greyish body; one black spot behind the eye and on the cheek; three to six black spots on the opercle; numerous black spots on the back (missing on the predorsal area), flank and middle part of body, surrounded by a roundish white ring; red spots in the median part of the body, surrounded by a roundish white ring; short and narrow maxilla; increase in the number of black and red spots with an increase in size; adipose fin medium size, no or rarely one red spot at its posterior edge; 109–116 lateral line scales; 27–30 scale rows between dorsal-fin origin and lateral line; 20–23 scale rows between the lateral line and anal-fin origin; maxilla length 8.8–10.0% standard length in males, 8.8–9.6 in females.     

A new species of Odontostilbe cope (Characiformes: Cheirodontinae) from rio Madeira basin diagnosed based on morphological and molecular data

A new species of Odontostilbe is described from the rio Jaciparaná, rio Madeira basin, Rondônia, Brazil. Odontostilbe pacaasnovos differs from all its congeners, except O. pequira, by the colour pattern. Additionally, it differs from its congeners by the terminal mouth, number of cusps in the teeth of the premaxilla (5–7), number of branched rays in the anal fin (19–22), by the shape of dentary teeth (5–7 cusps with central cusp larger and longer than laterals cusps) and by the number of lamellae of the olfactory rosette (17–18 in male and 14 in female). Morphological and molecular comparisons corroborate the distinctiveness between O. pacaasnovos and its congeners, justifying its recognition as a new species.     

Description of a new perchlet,Chelidoperca formosa,from southwestern Taiwan (Peciformes: Serranidae)

A new perchlet species is described on the basis of four specimens collected from southwestern Taiwan. It is similar to congeners with relatively few lateral-line scales (35–38) and can be distinguished by having third to sixth dorsal-fin spines notably long; eighth and ninth dorsal-fin spines notably short; developed gill rakers 1 + 7–8; scale rows between lateral line and sixth dorsal-fin spine 4 (the dorsalmost half-sized); tip of upper corner of caudal fin reddish; four reddish bands midlaterally on body with groups of melanophores in these bands. DNA barcoding analysis reveals the new species is a distinct lineage and closest to Chelidoperca microdon. The average interspecific genetic distance calculated by the K2P model is 15.4%, whereas the mean distance from the new species to C. microdon is 18.3%. The inferred phylogenetic tree supports monophyly of Chelidoperca. Including the new species, six nominal species of Chelidoperca are recognized in Taiwanese waters.     

A new species of the grenadier genus <Emphasis Type="Italic">Coelorinchus</Emphasis> (Actinopterygii: Gadiformes: Macrouridae) from the Timor Sea,Eastern Indian Ocean

Coelorinchus okamurai sp. nov. is described from five specimens collected in the Timor Sea at a depth of 610–690 m. The new species belongs to the Coelorinchus japonicus group (redefined in this study), and differs from all other congeners in having the following combination of features: snout moderately long, sharply pointed in lateral and dorsal views, length 39–42% of head length; lateral nasal ridge completely supported by nasal bone; light organ short, length less than 1/2 orbit diameter, its anterior margin falling far short of pelvic-fin bases; premaxillary teeth in short, uniformly wide band, with posterior end of the tooth band not reaching lateral corner of mouth; no teeth greatly enlarged; body scales covered with short, reclined, narrowly blade-like spinules in widely divergent rows; buttresses of body scale spinules scarcely developed; occipital scales between parietal ridges armed with divergent rows of long, erect, needle-like spinules; nasal fossa usually naked (a few small scales rarely present anteroventrally); patches of small scales sparsely distributed on ventral surface of head; scales on underside of head armed with 1–3 rows of short, erect, needle-like to knife-like spinules; interdorsal space longer than first dorsal-fin base length; subopercle terminating as a long, slender flap; body dark overall without prominent markings; fins uniformly blackish.     

A new anthiine fish (Perciformes: Serranidae),Holanthias kingyo, from the Ryukyu Islands

A new anthiine fish,Holanthias kingyo sp, nov., is described on the basis of two specimens (male and female) from the Ryukyu Is., Japan. The new species is most similar toH. natalensis (Fowler, 1925), known only from South Africa, in having the following characters: dorsal fin soft rays 16 or 17, anal fin soft rays 9, pored lateral line scales 46 or 47, scale rows above lateral line to origin of dorsal fin 9 1/2 or 10 1/2, and gill rakers 10 or 11 +24 or 25=34–36. It differs from the latter in having more scales below the lateral line to the origin of the anal fin (27 1/2 vs. 18–24), a U-shaped caudal fin with paddle-like lobes (vs. deeply forked caudal fin with each lobe ending in a long slender filament), the outer margin of the soft anal fin vertical (vs. gently convex) and brown spots on the body in female (vs. spots absent in females).     

Two new species of the genus <Emphasis Type="Italic">Leptochiton</Emphasis> (Mollusca,Polyplacophora) from north-western Pacific

Two new species of the genus Leptochiton, L. сommandorensis sp. nov. and L. incubatus sp. nov. from north-western Pacific are described. Leptochiton сommandorensis differs from the congeners in having radial rows of granules in the lateral areas of intermediate valves, unicuspid dental cap on major lateral teeth of the radula, and dorsal scales with two ribs. Leptochiton incubatus differs from the congeners in having one aesthete pore in each granule, a shallow depression between the central and lateral areas of intermediate valves and between the antemucronal and postmucronal areas of the tail valve, and unicuspid head of major lateral teeth of radula. This species is brooding.