Nitrogen offset in N2 multiple washout method.

An offset in the nitrogen signal significantly affects LCI measured by the N2 MBW method http://bit.ly/35hwOuH.

Revision of the circumglobal genus Barathronus (Ophidiiformes, Bythitidae) with a new species from the eastern North Atlantic Ocean.

The viviparous genus Barathronus Goode Bean, 1886 is known from 11 species. Examination of 68 specimens, not earlier published upon, and re-examination of older material have resulted in taxonomical changes and new distributions. B. unicolor Nielsen, 1984 has become a junior synonym of B. pacificus Nielsen Eagle, 1974, now known from the Atlantic and Pacific Oceans. The number of specimens of B. parfaiti Vaillant, 1888 is restricted to the holotype and a specimen from off the Azores (MOM P01-0003665), often referred to B. parfaiti, represents a new species, B. roulei, herein described. B. diaphanus Brauer, 1906 is now recorded from off Madagascar eastwards to Tonga and Fiji Islands.

Aphyonid-clade species of Australia (Teleostei, Bythitidae) with four species new to Australian waters and a new species of Barathronus.

During voyages in 2017 off southern and southeastern Australia, the Australian Research Vessel Investigator deployed a series of demersal beam trawls to depths of around 5000 metres. Nineteen specimens of the rarely caught aphyonid-clade of the ophidiiform family Bythitidae, representing five species, were caught. Four of these are new to Australian waters:  Barathronus pacificus Nielsen and Eagle, 1974 known from the northeastern and southwestern Pacific Ocean, Paraphyonus bolini (Nielsen, 1974) known from the western Indian and western Pacific Oceans, Paraphyonus rassi (Nielsen, 1975) known from the Atlantic Ocean and Sciadonus pedicellaris Garman, 1899, known from the northeastern Atlantic and northeastern and southwestern Pacific Oceans. Also included are Aphyonus gelatinosus Günther, 1878 known from all oceans including ten specimens from Australian waters, Barathronus maculatus Shcherbachev, 1976 known from South Africa to the westernmost Pacific including 13 specimens from Australian waters, Sciadonus longiventralis Nielsen, 2018 known from the holotype collected off New South Wales and finally Barathronus algrahami n. sp. known from the holotype caught off South Australia and four paratypes from off Taiwan and northern Philippines. Close examination of specimens collected during recent voyages combined with recent and ongoing studies by the first author and DNA COI barcoding analysis enabled an assessment of the aphyonid-clade species hitherto recorded from Australian waters. An identification key to the eight aphyonid clade species known from Australian waters is provided.

Impact of leaks in sulfur hexafluoride and nitrogen multiple-breath washout systems.

Sulfur hexafluoride multiple-breath washout is insensitive to inspiratory leaks http://ow.ly/Y3o830lKOpY.

Difference between SF6 and N2 multiple breath washout kinetics is due to N2 back diffusion and error in N2 offset.

Measurement of lung clearance index (LCI) by multiple breath washout (MBW) is a sensitive method for monitoring lung disease in patients with cystic fibrosis (CF). To compare nitrogen MBW (N2-MBW) and sulfur hexafluoride MBW (SF6-MBW), we connected these two gas analysis systems in series to obtain truly simultaneous measurements, with no differences other than the gas used. Nonsmoking healthy controls (HC) and subjects with CF were recruited at two institutions. The Exhalyzer-D (for N2-MBW measurement) was connected in series with the Innocor (for SF6-MBW measurement). Subjects washed in SF6 from a Douglas bag with tidal breathing and washed out SF6 and nitrogen with 100% oxygen provided as bias flow. Washout of both gases was continued past the LCI point (1/40th of equilibration concentration) in triplicate. N2-MBW resulted in higher cumulative exhaled volume, functional residual capacity (FRC), and LCI when compared with SF6-derived parameters in HC subjects (P < 0.0001 for all comparisons). All N2-MBW parameters were also significantly higher than SF6-MBW parameters in subjects with CF (P < 0.01 for all comparisons). After recalculation with a common FRC, N2-MBW LCI was higher than SF6-MBW LCI in subjects with CF (19.73 vs. 11.39; P < 0.0001) and in HC (8.12 vs. 6.78; P < 0.0001). Adjusting for N2 back diffusion and an offset error in the nitrogen measurement resulted in near complete agreement between the two methodologies. We found significant differences in LCI and FRC measurements using two different gases for MBW. This may have significant implications for the future use and interpretation of LCI data in clinical trials and routine clinical care.NEW & NOTEWORTHY This study provides important insights into the differences between the two techniques used for measuring lung clearance index (LCI): N2 and SF6 multiple breath washout. Differences between measurements made by these two methods in subjects with cystic fibrosis and healthy controls could be explained by nitrogen back diffusion and N2 offset error. This is important for use and interpretation of LCI data as an outcome measure for clinical trials and in routine clinical care.

Review of the steatiticus-species group of the cuskeel genus Neobythites (Ophidiidae) from the Indo-Pacific, with description of two new species.

This review was motivated by the recent collection of a specimen of the specious cuskeel genus Neobythites (Ophidiidae) off Myanmar and difficulties to identify it based on the available literature. This specimen has an ocellus consisting of a dark oval spot and a concentric white ring placed on the dorsal fin at mid-body, typical for many Neobythites species. It belongs to a group of single-ocellus bearing species which have no or only one weakly developed, flat preopercular spine which we term here the "steatiticus-species group". Before this study, the steatiticus group consisted of six Indo-Pacific species, N. longipes, N. malhaensis, N. malayanus, N. meteori, N. steatiticus, and N. stefanovi, and the Atlantic N. monocellatus. From 136 specimens representing the six Indo-Pacific steatiticus-group species counts or measurements of 12 meristic, 14 body shape, five ocellus and six otolith characters were obtained and compared, revealing two undescribed species. We describe N. gloriae n. sp. from the Arabian Gulf and inner Gulf of Oman based on nine specimens that had been previously misidentified as N. steatiticus and N. stefanovi. The latter species differ from the new species and from each other in the combination of five characters, head length, orbit length, gill-filament length, ocellus-spot distance, and ocellus-spot size. The second new species described is N. lombokensis n. sp. which consists of a single specimen from off SE Lombok, southern Indonesia. It differs from all other steatiticus-group species in having a larger ocellus spot and in several meristic and morphometric characters. The specimen from off Myanmar, eastern Bay of Bengal, was found to belong to N. steatiticus, providing new information on distribution and colour. Diagnoses, updated distribution information, and a key for the eight Indo-Pacific steatiticus-group species are here presented. We discuss our findings with special emphasis on the variation and possible function of colour patterns in Neobythites, being important for understanding the ecology and evolution of this specious genus.

Revision of the genus Nybelinella (Teleostei, Bythitidae) with a new Atlantic, abyssal species.

The genus Nybelinella belongs to the aphyonid clade within the Bythitidae. This mainly abyssal genus is known from 30 specimens. The present revision is based on 24 specimens, of which a scientific examination of four specimens has been published earlier. As a consequence, the generic diagnosis from Nielsen et al. (1999) is here modified. Of the 24 specimens 22 are referred to N. erikssoni (Nybelin, 1957), one to N. brevidorsalis Shcherbachev, 1976 and one to a new species, N. brevianalis n. sp., herein described.

Evolutionary affinities of the unfathomable Parabrotulidae: Molecular data indicate placement of Parabrotula within the family Bythitidae, Ophidiiformes.

Fishes are widely diverse in shape and body size and can quite rapidly undergo these changes. Consequently, some relationships are not clearly resolved with morphological analyses. In the case of fishes of small body size, informative characteristics can be absent due to simplification of body structures. The Parabrotulidae, a small family of diminutive body size consisting of two genera and three species has most recently been classified as either a perciform within the suborder Zoarcoidei or an ophidiiform. Classification of parabrotulids as ophidiiforms has become predominant; however the Parabrotulidae has not yet been investigated in a molecular phylogenetic framework. We examine molecular data from ten genetic loci to more specifically place the Parabrotulidae within the fish tree of life. In a hypothesis testing framework, the Parabrotulidae as a zoarcoid taxon is rejected. Previous identity with zoarcoids due to the one fin ray for each vertebra being present, a characteristic for the Zoarcidae, appears to be an example of convergence. Our results indicate that parabrotulids are viviparous ophidiiforms within the family Bythitidae.

A new species of Abyssobrotula (Ophidiiformes, Ophidiidae) from the Kuril-Kamchatka Trench.

A new abyssal ophidiid fish, Abyssobrotula hadropercularis, is described on the basis of two specimens caught at two stations at ca. 5000 meters of depth in the Kuril-Kamchatka Trench. The genus Abyssobrotula Nielsen, 1977 was previously known from the type species, A. galatheae Nielsen, 1977 of which 40-50 specimens now are reported from all oceans at depths greater than 2000 m. One of the specimens from the Puerto Rico Trench captured at 8370 m is still the deepest record for fishes. The new species differs from A. galatheae in having great number of pectoral-fin rays 14-15 (vs 10-11); greater eye diameter (1.2-1.3% SL vs 0.7-0.9% SL); larger prepelvic 14.0-14.5% SL (vs 10.5-12.5% SL) and preanal lengths 42.5% SL (vs 33.0-41.5% SL); opercular spine strongly developed (vs poorly developed); gill rakers on anterior arch robust and close-set (vs rakers thin and well separated). The description of A. hadropercularis makes it necessary to slightly modify the generic diagnosis.

Molecular, morphological and fossil input data for inferring relationship among viviparous brotulas (Bythitidae) - Resulting in a family status change for Dinematichthyidae.

This article comprise the data related to the research article (Møller et al., 2016) [1], and makes it possible to explore and reproduce the topologies that allowed [1] to infer the relationship between the families Bythitidae and Dinematichthyidae. The supplementary data holds nexus-input files for the Bayesian analysis and the '.xml'-input files - with and without nucleotide data - that are used in the fossil-calibrated phylogenetic analysis with a relaxed clock model. The resulting topologies are provided as '.new'-files together with a characters matrix file for traits to trace across the inferred phylogenies.

A new classification of viviparous brotulas (Bythitidae) - with family status for Dinematichthyidae - based on molecular, morphological and fossil data.

The order Ophidiiformes is a large but not very well known group of fishes, unique among teleosts for showing high diversity in both deep sea and shallow reef habitats. The current classification includes more than 500 species, 115 genera and four families, based primarily on mode of reproduction: viviparous Aphyonidae and Bythitidae vs oviparous Carapidae and Ophidiidae. Since 2004 we revised the bythitid tribe Dinematichthyini, described more than 100 new species and noticed that this group has unique morphological characters, perhaps supporting a higher level of classification than the current status. Here we study the viviparous families phylogenetically with partial mitochondrial (nd4, 16s) and nuclear (Rag1) DNA sequences (2194bp). We use a fossil calibration of otolith-based taxa to calibrate the age of the clade comprising bythitid and dinematicththyid representatives, together with fossil calibrations adopted from previous phylogenetic studies. The separation of the order into two major lineages, the viviparous Bythitoidei and the oviparous Ophidioidei is confirmed. At the familial level, however, a new classification is presented for the viviparous clades, placing Aphyonidae as a derived, pedomorphic member of Bythitidae (new diagnosis provided, 33 genera and 118 species). The current subfamily Brosmophycinae is considered polyphyletic and we propose family status for Dinematichthyidae (25 genera, 114 species), supported by unique, morphological synapomorphic characters in the male copulatory apparatus. Previous use of the caudal fin separation or fusion with vertical fins is ambiguous. Age estimates based on calibrated molecular phylogeny agrees with fossil data, giving an origin within the Cretaceous (between 84 and 104mya) for a common ancestor to Ophidiiformes.

Revision of the aphyonid genus Aphyonus (Teleostei, Ophidiiformes) with a new genus and two new species.

The cosmopolitan, deep sea, aphyonid genus Aphyonus is known from less than 100 specimens. The type species A. gelatinosus Günther, 1878 and three additional valid species, A. brevidorsalis Nielsen, 1969, A. bolini Nielsen, 1974, and A. rassi Nielsen, 1975 were all based on single specimens. Since then several specimens have been caught of which 52 are examined for the present revision. Most of the specimens are referred to A. gelatinosus but also to A. bolini and A. rassi. A result of the enlarged material is that the type species, A. gelatinosus, is found to differ so much from the remaining species that a new genus, Paraphyonus, is established for these species. Furthermore two new species of Paraphyonus are here described, P. iselini based on six specimens from the tropical northwestern Atlantic Ocean and P. merretti based on three specimens from the northeastern Atlantic Ocean. The present knowledge of the variation of the Paraphyonus species makes it relevant to transfer Barathronus solomonensis Nielsen & Møller, 2008 to this genus.

A new deep-sea species of Barathronus Goode & Bean from Brazil, with notes on Barathronus bicolor Goode & Bean (Ophidiiformes: Aphyonidae)

A new species of Barathronus (Ophidiiformes: Aphyonidae) is described from a single, mature male specimen (101 mm SL) bottom trawled on the continental slope of Rio Grande do Norte, northeastern Brazil, between 1,964 and 2,045 m depth. The new species is diagnosed among congeners by the following combination of characters: peritoneum transparent, deep-set eyes not visible, eight fangs on vomer, anal fin rays 69, predorsal length 42.0% SL, preanal length 49.5% SL, penis long, slender, and lacking a pair of lobes at its base, and presence of a ventral flexure of the anterior 2-3 vertebrae. Additionally, morphological data of three specimens of Barathronus bicolor collected in Brazilian waters are presented and compared with those from 51 specimens from the western Central Atlantic.

Uma nova espécie de Barathronus (Ophidiiformes: Aphyonidae) é descrita a partir de um único exemplar macho (101 mm CP) coletado com arrasto de fundo no talude continental do Rio Grande do Norte, nordeste do Brasil, entre 1.964 e 2.045 m de profundidade. A espécie nova é diagnosticada entre as congêneres pela seguinte combinação de caracteres: peritônio transparente, olhos alojados profundamente e não distinguíveis, oito presas no vômer, nadadeira anal com 69 raios, comprimento pré-dorsal 42,0% CP, comprimento pré-anal 49,5% CP, pênis longo, afilado e sem um par de lobos em sua base, e presença de flexão ventral nas 2-3 vértebras anteriores. Adicionalmente, dados morfológicos dos três espécimes de Barathronus bicolor coletados em águas brasileiras são apresentados e comparados com aqueles de 51 espécimes do Atlântico Central ocidental.

Evaluation of the impact of alveolar nitrogen excretion on indices derived from multiple breath nitrogen washout.

BACKGROUND: A large body of evidence has now accumulated describing the advantages of multiple breath washout tests over conventional spirometry in cystic fibrosis (CF). Although the majority of studies have used exogenous sulphur hexafluoride (SF6) as the tracer gas this has also led to an increased interest in nitrogen washout tests, despite the differences between these methods. The impact of body nitrogen excreted across the alveoli has previously been ignored. METHODS: A two-compartment lung model was developed that included ventilation heterogeneity and dead space (DS) effects, but also incorporated experimental data on nitrogen excretion. The model was used to assess the impact of nitrogen excretion on washout progress and accuracy of functional residual capacity (FRC) and lung clearance index (LCI) measurements. RESULTS: Excreted nitrogen had a small effect on accuracy of FRC (1.8%) in the healthy adult model. The error in LCI calculated with true FRC was greater (6.3%), and excreted nitrogen contributed 21% of the total nitrogen concentration at the end of the washout. Increasing DS and ventilation heterogeneity both caused further increase in measurement error. LCI was increased by 6-13% in a CF child model, and excreted nitrogen increased the end of washout nitrogen concentration by 24-49%. CONCLUSIONS: Excreted nitrogen appears to have complex but clinically significant effects on washout progress, particularly in the presence of abnormal gas mixing. This may explain much of the previously described differences in washout outcomes between SF6 and nitrogen.