Length‐weight and length‐length relationships of Balitora brucei Gray, 1830 and Psilorhynchus balitora (Hamilton, 1822) from the Ranganadi river of Assam,India

The study describes length‐weight relationships (LWRs) and length‐length relationships (LLRs) for two species of fishes, namely Balitora brucei Gray, 1830 and Psilorhynchus balitora (Hamilton, 1822) collected from Ranganadi river in Lakhimpur district of Assam, India for which no LWRs and LLRs are available. While sampling monthly between April 2012 and July 2016, a total of 987 specimens were collected (B. brucei = 427, and P. balitora = 560). Cast nets were used (2 ‐ 10 mm mesh sizes; 2–2.5 m length). The values of the parameter slope (b) in the LWR were determined as 3.194 (male = 3.047 and female = 3.224) for B. brucei and 3.490 (male = 3.480 and female = 3.502) for P. balitora. Present investigation reports new maximum total length for both the fishes.     

Osteology of the South Asian Genus Psilorhynchus McClelland, 1839 (Teleostei: Ostariophysi: Psilorhynchidae), with investigation of its phylogenetic relationships within the order Cypriniformes

Members of the genus Psilorhynchus are small benthic fishes, commonly referred to as torrent minnows, which inhabit the fast to swift flowing water bodies of the Indo‐Burma region and the Western Ghats of Peninsular India. Despite being described scientifically in the mid 18^th century, the morphology of Psilorhynchus remains poorly known and its phylogenetic placement within the order Cypriniformes is a matter of considerable debate. In this paper the osteology of Psilorhynchus sucatio is described and illustrated in detail. Notes and/or illustrations on the osteology of 12 other species of Psilorhynchus are also provided for the first time. A phylogenetic investigation of the position of Psilorhynchus within the order Cypriniformes is also conducted. Analysis of 127 morphological characters scored for 52 ingroup taxa (including 12 species of Psilorhynchus) and four outgroup taxa resulted in 14 equally parsimonious cladograms (287 steps long; consitency index, CI = 0.48; retention index, RI = 0.88). Psilorhynchus is recovered as the sister group to the family Cyprinidae, and is regarded as a member of the superfamily Cyprinoidea, which forms the sister group to the Cobitoidea (including all other cypriniform families). The sistergroup relationship between Psilorhynchus and Cyprinidae is supported by eight derived characters (five of which are homoplastic within the order Cypriniformes). The monophyly of Psilorhynchus is supported by 16 derived characters (eight of which are homoplastic within Cypriniformes). Three species groups of Psilorhynchus are proposed, the Psilorhynchus balitora group (including P. amplicephalus, P. balitora, P. breviminor, P. nepalensis, P. rahmani, P. pavimentatus, and P. brachyrhynchus), the Psilorhynchus gracilis group (including P. gracilis, P. melissa, P. robustus, and P. tenura), and the Psilorhynchus homaloptera group (including P. arunachalensis, P. homaloptera, P. microphthalmus, and P. pseudecheneis). The continued use of the family group name Psilorhynchidae is recommended. Comments on the interrelationships of the Cypriniformes are also provided. © 2011 The Linnean Society of London, Zoological Journal of the Linnean Society, 2011.     

Length–weight relationships of four indigenous fish species from Brahmaputra River,Assam, India

The present study was undertaken with the objective to estimate the length‐weight Relationships (LWRs) for four species collected from the Brahmaputra River, Assam, India. The fish samples were collected quarterly from different sampling sites using gill net (mesh size ranges 1–1.5 cm, locally called Mola lungi jal), cast net (mesh size ranges 1.0–2.0 cm, locally called Kevalijal) and triangular dip nets (mesh size ranges 0.75–1.25 cm locally called khorajal) during the time period between May, 2016 to April, 2018 (2 years). The b value of the LWR ranged from 3.028 (for Parambasis lala) to 3.196 (for Psilorynchus balitora). In this study the relationship between length‐weight were highly correlated (p < 0.05).     

Molecular systematics of the Asian torrent minnows (Ostariophysi: Psilorhynchidae) inferred from nuclear and mitochondrial DNA sequence data

The phylogenetic relationships between members of the South Asian family Psilorhynchidae are investigated using both mitochondrial and nuclear DNA sequence data. Phylogenetic hypotheses were derived from maximum likelihood and maximum parsimony analyses of a three gene concatenated data set, including cytochrome c oxidase subunit 1 (640 bp), cytochrome b (1140 bp) and exon 3 of the recombination‐activating gene 1 (~1500 bp). Our investigation provides strong support for the monophyly of two species groups of Psilorhynchus (the P. balitora and P. nudithoracicus species groups) and corroborates previous hypotheses on the phylogenetic position of the Western Ghats species Psilorhynchus tenura based on morphology. Basal relationships within Psilorhynchus were poorly supported and are worthy of further investigation. A fossil calibrated relaxed molecular clock estimates the split between Psilorhynchus and its sister group to have occurred within the Eocene/Oligocene, with subsequent diversification in the Miocene.     

Description of a new species of Mustura Kottelat (Teleostei: Nemacheilidae) from the Brahmaputra drainage,India

Mustura subhashi, new species, is described from the Dikal River, a north bank tributary of the Brahmaputra drainage in Arunachal Pradesh. It is distinguished from all its congeners by having a colour pattern of 14–23 dark-greyish black to dark brown irregular bars on a greyish to pale beige body; pre-dorsal bars thin, numerous, wider than interspaces, weakly contrasted, uniting dorsally at lateral one-third or midway on flank to form thicker bars, coalescing further at lateral one-fifth and continuous on dorsum with contralateral bars; bars below dorsal fin exhibiting similar condition but slightly wider than pre-dorsal bars; post-dorsal bars thicker than anterior bars, wider than interspaces, sharply contrasted, rarely coalescing on flank; and a short bar along the caudal mid-line, rarely forming a blotch. Based on re-examination of the type specimens and additional materials, Mustura dikrongensis is confirmed as a species belonging to Mustura, and M. harkishorei is not sufficiently diagnosed from 'Nemacheilus' corica.     

Psilorhynchus ngathanu,a new torrent minnow species (Teleostei: Psilorhynchidae) from the Chindwin Basin,Manipur, India

Psilorhynchus ngathanu, a new psilorhynchid species, is described from the Dutah River, Chindwin Basin in Manipur, India. The new species is distinct from its congeners in the absence of scales from the midventral region between the pectoral fins, the presence of two rows of spots on the dorsal-fin rays and two black bars on the caudal fin, v–vi unbranched pectoral-fin rays, and 10 + 9 principal caudal-fin rays.     

<Emphasis Type="Italic">Olyra parviocula</Emphasis>, a new species of bagrid catfish (Actinopterygii: Siluriformes), from northeastern India

A new species, Olyra parviocula, is described from the Kameng River, Brahmaputra River drainage in Arunachal Pradesh, northeastern India. The new species differs from congeners in having small eye diameter 5–8% HL; short adipose fin, not confluent with caudal-fin, its base length 9–12% SL; dorsal-fin branched rays 6; anal-fin rays viii–xi, 8–10 and maxillary barbel almost reaching pelvic-fin base. A key to identification of all valid species of Olyra is provided.     

Length–weight relationships for selected fish species of Rio Trombetas Biological Reserve: a reference study for the Amazonian basin

Length–weight relationships (LWR) are presented for 27 freshwater fish species representing 11 families captured in the Trombetas River, a clearwater left margin tributary of the Amazon River. The allometry coefficient (b) of the LWR (W = aTL^b) ranged from 2.51 to 3.49, with a median value of 3.00. This study represents the first reference on LWR for 23 species and new records of maximum lengths for 15 species.     

Length–weight and length–length relationships of five threatened fish species from the Jamuna (Brahmaputra River tributary) River,northern Bangladesh

The small indigenous species, namely Ailiichthys punctata (Day, 1871), Botia lohachata (Chaudhuri, 1912), Chanda nama (Hamilton, 1822), Laubuca laubuca (Hamilton, 1822) and Mystus cavasius (Hamilton, 1822), comprise an important component of riverine fisheries of Bangladesh. This study describes the length–weight relationships (LWRs) and length–length relationships (LLRs) of five threatened fishes from the Jamuna River, a distributary of the Brahmaputra River in northern Bangladesh. A total of 919 specimens from five species in five families used for this study were caught by traditional fishing gear, March 2010 through February 2011. The allometric coefficient (b) of the LWRs indicated negative allometric growth in A. punctata, B. lohachata, and C. nama (b < 3.00), but positive allometric growth in L. laubuca and M. cavasius (b > 3.00). Furthermore, the LLRs were highly correlated (r² > 0.978; P < 0.001). This study presents the first reference on LWRs and LLRs for these threatened species in Bangladesh. The results would be useful for sustainable management and conservation of the limited stocks in the Brahmaputra River ecosystem.     

Length–weight relationships of Garra birostris Nebeshwar & Vishwanath, 2013, Garra annandalei (Hora, 1921), Johnius coitor (Hamilton, 1822) and Raiamas bola (Hamilton, 1822) from the Brahmaputra River basin,Northeast India

Length–weight relationships (LWRs) for one percoid (Johnius coitor) and three cyprinid (Garra birostris, Garra annandalei and Raiamas bola) fish species from the Brahmaputra River basin in Assam, Northeast India, was studied on a monthly basis from November 2015 to December 2016, using fishing gears namely, cast nets (9′, 1/2″) and gillnets (30 × 0.9 m). No previous record is available on LWR data for three of these species.     

TAXONOMY AND ULTRASTRUCTURE OF GOMPHONEIS MESTA SP. NOV. (BACILLARIOPHYTA), A NEW EPILITHIC DIATOM FROM THE MESTA RIVER,BULGARIA1

A new species from the diatom genus Gomphoneis, G. mesta, was described following morphological and ultra-structural analyses of its frustules by light and scanning electron microscopy. The valve striation consisting of double rows of areolae and the presence of longitudinal lines dictate the systematic position of this taxon in the genus Gomphoneis. The set of features that distinguishes G. mesta from allied taxa is small valves, 26.5–81.6 μm in length and 7–12.5 μm in width, lanceolate to clavate shape, with a broadly lanceolate axial area, and longitudinal lines positioned next to the valve margins, thus contributing to a general thickening of the valve outline. When compared to other members of the genus, G. mesta most resembles G. magna Kociolek & Stoermer. Gomphoneis mesta dominates the epilithic community, growing in the Cherna Mesta, a pristine high-mountainous tributary of the Mesta River in Bulgaria. The species has been also found as small populations in all other benthic habitats of the Cherna Mesta and in a few locations along the Mesta River.     

Length–weight relationships of Hara hara (Hamilton, 1822), Pangio pangia (Hamilton, 1822) and Setipinna brevifilis (Valenciennes, 1848) from the lower Brahmaputra River,Northeast India

The present study describes the length–weight relationships (LWRs) for Hara hara, Pangio pangia and Setipinna brevifilis from the lower Brahmaputra River in Assam, Northeast India, collected from June 2016 to May 2017, using fishing gears namely cast nets (9′, 1 ⁄ 2″) and gillnets (30 × 0.9 m). No previous data have ever been recorded on LWR for these three species.     

Length–weight relationships of fish from Madeira River,Brazilian Amazon,before the construction of hydropower plants

Length–weight relationships (LWRs) are presented for 112 freshwater fish species representing 23 families and five orders captured in the Madeira River, the largest white‐water river tributary of the Amazon River. The allometry coefficient (b) of the LWR (Wt = aSL^b) ranged from 2.446 to 3.856 with a median value of 3.102. Eight new LWR records are presented for Amazonian species as information for FishBase. LWRs in the present study provide historical data on a and b coefficients prior to the damming of the Madeira River in November 2011, allowing comparison estimates of predicted future population parameters as influenced by human intervention.     

Length–weight relationships of two cyprinid fish species,Crossocheilus latius (Hamilton, 1822) and Garra gotyla gotyla (Gray, 1830) from the Ganga River Basin,India

This study provides length–weight relationship (LWR) information for two fish species (family Cyprinidae), Crossocheilus latius (Hamilton, 1822) and Garra gotyla gotyla (Gray, 1830), from a tributary of the Ganga River Basin, India. Both species had no previous LWR estimates as per Fishbase 2014.     

Length–weight relationships and reproductive parameters of Amblyceps apangi Nath and Dey, 1989 from Nagaland,India

The present study describes certain biological parameters of a hill stream catfish, Amblyceps apangi Nath and Dey, 1989 first described from Arunachal Pradesh, India. The distributional range of the fish was later recorded from the states of Manipur and Nagaland. The fish is very rare and this is the first report on certain biological parameters based on collections (140 males, 105 females) from streams in the Doyang watershed, a tributary of the Brahmaputra River. The value of the allometric coefficient (b) indicated close to isometric growth in males (2.989) and negative allometric growth in females (2.945). The relative condition factor was found to be close to 1 in different size groups. Both males and females attained first maturity (M₅₀) in length group 6.0–7.0 cm. Peak values (Male 0.424, Female 1.465) in the gonadosomatic index (GSI) occurred from April to May, indicating one spawning season per year. The overall female to male ratio was 1 : 1.33. Absolute fecundity ranged from 17 to 122 for fishes of total length 6.34–10.3 cm.     

Phenotypic plasticity raises questions for taxonomically important traits: a remarkable new Andean rainfrog (Pristimantis) with the ability to change skin texture

We describe a new frog, Pristimantis mutabilis sp. nov., from the Andes of Ecuador. Individuals of the new species are remarkable for their ability to change skin texture from tuberculate to almost smooth in a few minutes, being the first documented amphibian species to show such dramatic phenotypic plasticity. The new taxon is assigned to the P. myersi group. It differs from other members of its group by body size (adult males 17.2–17.4 mm; adult females 20.9–23.2 mm), arboreal habitat, and red flash coloration in females. We document three call types for the new species, which differ through their number of notes and amplitude peaks. The three types are pulsed calls that share a dominant frequency of 3186.9–3445.3 Hz. Surprisingly, we also document similar skin texture plasticity in species (P. sobetes) from a different species group, suggesting that this ability might be more common than previously thought. The discovery of these variable species poses challenges to amphibian taxonomists and field biologists, who have traditionally used skin texture and presence/absence of tubercles as important discrete traits in diagnosing and identifying species. Reciprocal monophyly and genetic distances also support the validity of the new species, as it has distances of 15.1–16.3% (12S) and 16.4–18.6% (16S) from the most similar species, Pristimantis verecundus. Additionally, each of the two known populations of Pristimantis mutabilis are reciprocally monophyletic and exhibit a high genetic distance between them (5.0–6.5%). This pattern is best explained by the presence of a dry valley (Guayllabamba River) that seems to be acting as a dispersal barrier. © 2015 The Linnean Society of London     

Length–weight and length–length relationships of 26 fish species from the Yiluo River,a tributary of the Yellow River,China

From February to October 2016, a total of 9,754 fish specimens were collected from the Yiluo River, a tributary of the Yellow River, China's second longest river. Based on these samples, length–weight relationships (LWRs) and length–length relationships (LLRs) were estimated for 26 species. Among these data, LWRs for 1 species, LLRs for 11 species, and maximum total lengths for six species were not previously recorded in FishBase. The a values of the LWRs varied between 0.0019 and 0.0116, and b values from 2.805 to 3.883. All regressions for LWRs and LLRs were highly significant (p < .001). These results will be useful for sustainable management and conservation of the fish resources in the Yiluo River and the Yellow River ecosystem.     

Length–weight relationships of three catfish species from a tributary of the Dhaleshwari River,Bangladesh

The present ichthyological report describes the length‐weight relationships (LWRs) of three catfish species (Eutropiichthys murius, Nangra nangra and Gagata viridescens) belonging to two families from the Kaliganga River, a tributary of the Dhaleshwari River, Bangladesh. The analyses included 306 specimens collected monthly from fishermen's catches during October 2015 to April 2016. Ranges of regression parameters a and b of the three species were within 0.0058–0.0099 and 2.900–3.142, respectively with highly correlated coefficients of determination (r² > .995; p < .001). The LWRs for all three species presented herein for the first time with a new maximum length record for N. nangra.     

Description of a new species of the genus Awaous Valenciennes, 1837 (Gobiiformes: Oxudercidae) from the middle stretch of the Mahanadi River,Odisha, India,with comments on the Awaous species from India

A new species of the genus Awaous (Oxudercidae), Awaous motla sp. nov., is described based on 18 specimens collected from the Mahanadi River near Sonepur, Subarnapur District, and 3 specimens from the same river near Boudh bridge, Boudh District of Odisha, India. This species is distinct from its congeners by having a combination of characteristics: relatively small eyes, diameter of 6.6–8.4 in head length (LH); robust and long snout, 2.0–2.6 in LH; eye diameter 2.7–4.1 in snout length; cephalic sensory pore system interrupted with eight pores; predorsal scales 13–15; longitudinal scale series 55–58; gill rakers 2 + 1 + (6–7) on the first gill arch; teeth small, conical, and in a single row on the upper jaw and multiserial (2–3) on the lower jaw. This species is also differentiated from some of its congeners in the nucleotide composition of the cytochrome c oxidase I gene by 8.3%–13.8% Kimura two-parameter (K2P) distance and belongs to a separate cluster in the maximum likelihood tree analysis. This finding is also supported by the species delimitation analysis based on Assemble Species by Automatic Partitioning. The new species holds high commercial value in its locality and needs special conservation attention for sustainable utilization.     

A new cavefish of Sinocyclocheilus (Teleostei: Cypriniformes: Cyprinidae) from the Nanpanjiang River in Guizhou,China

A new species, Sinocyclocheilus xingyiensis, is described based on specimens collected from a karst cave in Guizhou Province, China. The authors used an integrated taxonomic approach, including morphological and molecular data, to identify the new species as a member of the Sinocyclocheilu angularis group, and it can be distinguished from all other members of this group by a combination of the following features: two pairs of long barbels and long pectoral fins, 42–46 lateral-line scales, 7 (13–14) on outer (inner) side of the first gill arch and 35 (14–15 + 4 + 16 − 17) vertebrae. Phylogenetic analyses based on the cytochrome b (cyt b) gene fragment suggest that S. xingyiensis is a sister lineage to Sinocyclocheilus flexuosdorsalis. The genetic distance (Kimura 2-parameter) between the S. xingyiensis and S. angularis groups of Sinocyclocheilus species based on cyt b gene fragment ranged from 1.2% to 15.4%.