title: PeerJ description: Articles published in PeerJ link: https://peerj.com/articles/index.rss3?journal=peerj&page=1278 creator: info@peerj.com PeerJ errorsTo: info@peerj.com PeerJ language: en title: Nurhachius luei, a new istiodactylid pterosaur (Pterosauria, Pterodactyloidea) from the Early Cretaceous Jiufotang Formation of Chaoyang City, Liaoning Province (China) and comments on the Istiodactylidae link: https://peerj.com/articles/7688 last-modified: 2019-09-19 description: A new istiodactylid pterosaur, Nurhachius luei sp. nov., is here reported based on a complete skull with mandible and some cervical vertebrae from the lower part of the Jiufotang Formation of western Liaoning (China). This is the second species of Nurhachius, the type-species being N. ignaciobritoi from the upper part of the Jiufotang Formation. A revised diagnosis of the genus Nurhachius is provided, being this taxon characterized by the presence of a slight dorsal deflection of the palatal anterior tip, which is homoplastic with the Anhangueria and Cimoliopterus. N. luei sp. nov. shows an unusual pattern of tooth replacement, with respect to other pterodactyloid species. The relationships within the Istiodactylidae and with their closest taxa are investigated through a phylogenetic analysis by parsimony. creator: Xuanyu Zhou creator: Rodrigo V. Pêgas creator: Maria E.C. Leal creator: Niels Bonde uri: https://doi.org/10.7717/peerj.7688 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2019 Zhou et al. title: LC–MS/MS quantitative analysis of phylloquinone, menaquinone-4 and menaquinone-7 in the human serum of a healthy population link: https://peerj.com/articles/7695 last-modified: 2019-09-19 description: A novel application of the liquid chromatography method combined with the triple quadrupole tandem mass spectrometry method was developed for the quantification of vitamin K1 and two forms of vitamin K2 (menaquinone-4, menaquinone-7) in human serum. Total chromatography time for each run was 9 min. Time required for the sample pretreatment procedures was approximately 4 h. The coefficients of variation (CVs) of intra-assay were 10.4%, 3.2 % and 2.3% for vitamin K1 in three levels of quality control samples; were 14.3%, 3.2% and 6.7% for menaquinone-4; and were 11.1%, 6.0% and 7.0% for menaquinone-7. The inter-assay CVs were 12.8%, 11.3% and 7.4% for vitamin K1; were 15.2%, 9.2% and 8.7% for menaquinone-4; and were 13.2%,11.1% and 7.2% for menaquinone-7. No interference was found between K1, menaquinone-4 and menaquinone-7, nor any deuterated internal standards. This method was then used to determine reference values for Caucasian populations of central European origin. Samples were measured from 191 healthy volunteers (51.2 ± 16.2 years (mean ± SD)) and the values concerning K1 were 0.044–1.357 ng/mL for women and 0.030–1.214 ng/mL for men. The values for menaquinone-4 and menaquinone-7 did not exhibit any differences between women and men, and were 0.050–1.598 and 0.074–0.759 ng/mL, respectively. creator: Katerina Dunovska creator: Eva Klapkova creator: Bruno Sopko creator: Jana Cepova creator: Richard Prusa uri: https://doi.org/10.7717/peerj.7695 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2019 Dunovska et al. title: Phylogeny of Microphthalminae Hartmann-Schröder, 1971, and revision of Hesionella Hartman, 1939, and Struwela Hartmann-Schröder, 1959 (Annelida, Errantia) link: https://peerj.com/articles/7723 last-modified: 2019-09-19 description: Microphthalminae Hartmann-Schröder, 1971 was proposed in Hesionidae to include Microphthalmus and Hesionides; however, the affinities of these genera to other members of Hesionidae have been debated, and some authors have concluded they do not belong in Hesionidae. Herein, based on morphological characters, a phylogenetic analysis of the subfamily and some other similar poorly-known genera, with an uncertain position in Hesionidae was performed to clarify their affinities. Our results indicate that Microphthalminae, as currently delimited, is paraphyletic. The inclusion of Struwela, Uncopodarke, and Westheideius, a new genus, as well as the recognition of Fridericiella are proposed to meet the requirement of monophyly; and as result of this, the elevation in rank to the family level is herein presented. Furthermore, the type species for Hesionella and Struwela are redescribed, and a new species in the latter is described. A key to identify microphthalmid genera is also included. creator: Sergio I. Salazar-Vallejo creator: Jesús Angel de León-González creator: Luis F. Carrera-Parra uri: https://doi.org/10.7717/peerj.7723 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2019 Salazar-Vallejo et al. title: The secret life of deep-sea shrimps: ecological and evolutionary clues from the larval description of Systellaspis debilis (Caridea: Oplophoridae) link: https://peerj.com/articles/7334 last-modified: 2019-09-18 description: Currently there are 21 shrimp species in the northeastern Atlantic and Mediterranean Sea which are considered to belong to the superfamily Oplophoroidea, but the larval development is unknown for most of them. The complete larval development of Systellaspis debilis (Milne-Edwards, 1881), here described and illustrated, is the first one to have been successfully reared in the laboratory, consisting of four zoeal and one decapodid stages. The zoeae were found to be fully lecithotrophic, which together with the females’ lower fecundity, are probably evolutionary consequences of the species mesopelagic habitat. creator: Cátia Bartilotti creator: Antonina Dos Santos uri: https://doi.org/10.7717/peerj.7334 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2019 Bartilotti and Dos Santos title: Open ocean nocturnal insect migration in the Brazilian South Atlantic with comments on flight endurance link: https://peerj.com/articles/7583 last-modified: 2019-09-18 description: We observed a nocturnal insect swarm aboard the oceanographic ship Cruzeiro do Sul of the Brazilian Navy, while conducting a survey of the Montague guyot (seamount), 389 km distant from the nearest land in the South Atlantic. The insects came from open sea toward the ship from all directions, attracted by the powerful light of the deck. Most insects collided with the hull and fell into the ocean, but we managed to capture and determine 17 (13 Hemiptera of a single species, three Lepidoptera of three species and one Odonata). With one exception, we are certain that none of the specimens caught originated from the ship. The geographic origin, most likely the coast of Brazil, and flight endurance of these insects were inferred using data on wind speed and direction, provided by the crew of the ship, and were reconstructed using Hysplit modeling of air current trajectories. creator: Ruy J.V. Alves creator: Luíz A.A. Costa creator: Alexandre Soares creator: Nílber G. Silva creator: Ângelo P. Pinto uri: https://doi.org/10.7717/peerj.7583 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2019 Alves et al. title: Measuring body dimensions of leopards (Panthera pardus) from camera trap photographs link: https://peerj.com/articles/7630 last-modified: 2019-09-18 description: Measurement of body dimensions of carnivores usually requires the chemical immobilization of subjects. This process can be dangerous, costly and potentially harmful to the target individuals. Development of an alternative, inexpensive, and non-invasive method therefore warrants attention. The objective of this study was to test whether it is possible to obtain accurate measurements of body dimensions of leopards from camera trap photographs. A total of 10 leopards (Panthera pardus) were captured and collared at Malilangwe Wildlife Reserve, Zimbabwe from May 7 to June 20, 2017 and four body measurements namely shoulder height, head-to-tail, body, and tail length were recorded. The same measurements were taken from 101 scaled photographs of the leopards recorded during a baited-camera trapping (BCT) survey conducted from July 1 to October 22, 2017 and differences from the actual measurements calculated. Generalized Linear Mixed Effects Models were used to determine the effect of type of body measurement, photographic scale, posture, and sex on the accuracy of the photograph-based measurements. Type of body measurement and posture had a significant influence on accuracy. Least squares means of absolute differences between actual and photographic measurements showed that body length in the level back-straight forelimb-parallel tail posture was measured most accurately from photographs (2.0 cm, 95% CI [1.5–2.7 cm]), while head-to-tail dimensions in the arched back-bent forelimb-parallel tail posture were least accurate (8.3 cm, 95% CI [6.1–11.2 cm]). Using the BCT design, we conclude that it is possible to collect accurate morphometric data of leopards from camera trap photographs. Repeat measurements over time can provide researchers with vital body size and growth rate information which may help improve the monitoring and management of species of conservation concern, such as leopards. creator: Allan Tarugara creator: Bruce W. Clegg creator: Edson Gandiwa creator: Victor K. Muposhi creator: Colin M. Wenham uri: https://doi.org/10.7717/peerj.7630 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2019 Tarugara et al. title: 13C values of glycolytic amino acids as indicators of carbohydrate utilization in carnivorous fish link: https://peerj.com/articles/7701 last-modified: 2019-09-18 description: BackgroundStable isotope analysis of single amino acids (AA) is usually applied in food web studies for tracing biosynthetic origins of AA carbon backbones and establishing trophic positions of consumers, but the method is also showing promise for characterizing quantity and quality of dietary lipids and carbohydrates.MethodsTo investigate whether changes in high- and low-digestible carbohydrates affect δ13C values of glycolytic AA, i.e., AA carbon backbones sourced from the glycolytic pathway, we compared Atlantic salmon (Salmo salar) from a feeding experiment with and without dietary inclusion of the red macroalga Palmaria palmata. The Control and experimental diets had similar relative proportions of macronutrients, but their ingredients differed; in the experimental treatment, 15% Palmaria inclusion substituted proteins from fishmeal and carbohydrates from corn starch.ResultsWe found that 13C values of the glycolytic AA were highly sensitive to substitution of corn starch with Palmaria. The δ13C offsets of glycolytic AA between salmon and their diets were significantly greater in the Palmaria inclusion than Control treatment. This greater offset can be attributed to the different utilization of high- vs. low-digestible carbohydrate sources, i.e., corn starch vs. Palmaria, in the two treatments, and metabolic routing of dietary lipids. In addition, similar δ13C values of essential AA between treatments indicate similar nutrient assimilation efficiency for all terrestrial (pea protein concentrate and wheat gluten meal) and marine (fishmeal and red alga) derived protein sources. These results show that δ13CAA analysis is a promising tool for improving our understanding of how carnivorous fish utilize macronutrient and route metabolic intermediates to tissue. creator: Yiming V. Wang creator: Alex H.L. Wan creator: Åshild Krogdahl creator: Mark Johnson creator: Thomas Larsen uri: https://doi.org/10.7717/peerj.7701 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2019 Wang et al. title: Dynamics of carbon and nitrogen storage in two typical plantation ecosystems of different stand ages on the Loess Plateau of China link: https://peerj.com/articles/7708 last-modified: 2019-09-18 description: In China’s Loess Plateau, afforestation and reforestation are considered the foremost practices for sequestering carbon and conserving soil and water. In order to evaluate the carbon storage changes of tree, soil, and litter, and the soil total nitrogen (STN) in two typical artificial forests in the region, we conducted plot surveys for different ages of both artificial forest types. Soil samples were collected at different depths from 0–100 cm. The results indicated that forest ecosystem carbon storage increased with tree development. The rates of mean annual carbon sequestration of Pinus tabulaeformis and Robinia pseudoacacia plantation ecosystems were 3.31 and 3.53 Mg ha−1 year−1, respectively. The rate of mean annual carbon sequestration of R. pseudoacacia plantation ecosystems was higher by 6.65% than that of P. tabulaeformis plantation ecosystems. The soil organic carbon (SOC) and STN decreased at deeper soil depths in both plantations at different stand ages, significantly decreasing in the 0–60 cm of soil (P < 0.05), and the highest SOC content and storage were in the top 0–20 cm of soil. The temporal patterns for SOC and STN changes at different soil sampling depths from 0 to 100 cm all showed an initial decrease during the early stage of restoration, and then an increase that coincided with the development of the two plantation forests. At 0–100 cm depth, the SOC storage was in the range of 40.95–106.79 and 45.13–113.61 Mg ha−1 for the P. tabulaeformis forest and R. pseudoacacia forest, respectively. The STN storage in the 0–100 cm soil layer with the stand age development ranged from 4.16 to 8.34 Mg ha−1 in the R. pseudoacacia plantation and 4.19–7.55 Mg ha−1 in the P. tabulaeformis forest. The results showed a significant positive correlation between SOC and STN. This study suggests that we should pay more attention to changes in soil carbon and nitrogen sequestration during long-term vegetation restoration. creator: Yanfang Wang creator: Ling Liu creator: Feixue Yue creator: Dong Li uri: https://doi.org/10.7717/peerj.7708 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2019 Wang et al. title: Mismatches between the genetic and phenotypic sex in the wild Kou population of Nile tilapia Oreochromis niloticus link: https://peerj.com/articles/7709 last-modified: 2019-09-18 description: Sex determination and sex chromosomes can be very diverse between teleost species. The group of tilapias shows a polymorphism in sex determination not only between closely related species but also between domestic strains within a species. In the Nile tilapia, the major effect genes and therefore the Y chromosome have been located on either linkage group 1 (LG1) or LG23 depending on the strains. In a Japanese strain, the sex determinant of LG23 (the amhY gene) has been identified as a duplicated amh (anti-Müllerian hormone) gene, with its gametolog found on the X chromosome (amhX). AmhY is located in tandem with the amhΔY gene (a truncated form) on the Y chromosome. X and Y chromosome markers based on the amh genes have been validated only on a few domestic strains but not in wild populations. Here, we used four of these markers in order to examine (1) the possible variation in sex determination of a wild population of Nile tilapia living in Lake Kou (Burkina Faso), (2) putative polymorphisms for these amh copies and (3) the existence of sex reversed individuals in the wild. Our genotyping of 91 wild Kou individuals with the amh sex-diagnostic markers of LG23 showed that while phenotypic females were all XX, phenotypic males were either XY or XX. Progeny testing of eight of these XX males revealed that one of these males consistently sired all-female progenies, suggesting that it is a wild sex reversed male (which could result from high temperature effects). The other XX males gave balanced sex ratios, suggesting that sex is controlled by another locus (possibly on another LG) which may be epistatically dominant over the LG23 locus. Finally, identification of unexpected amh genotypes was found for two individuals. They produced either balanced or female-biased sex ratios, depending on the breeder with whom they were crossed, suggesting possible recombination between the X and the Y chromosomes. creator: Rokyatou Sissao creator: Helena D’Cotta creator: Jean-François Baroiller creator: Aboubacar Toguyeni uri: https://doi.org/10.7717/peerj.7709 license: https://creativecommons.org/licenses/by/4.0/ rights: ©2019 Sissao et al. title: Chemical characterisation of potential pheromones from the shoulder gland of the Northern yellow-shouldered-bat, Sturnira parvidens (Phyllostomidae: Stenodermatinae) link: https://peerj.com/articles/7734 last-modified: 2019-09-18 description: Bats of the genus Sturnira (Family Phyllostomidae) are characterised by shoulder glands that are more developed in reproductively mature adult males. The glands produce a waxy secretion that accumulates on the fur around the gland, dyeing the fur a dark colour and giving off a pungent odour. These shoulder glands are thought to play a role in their reproductive behaviour. Using gas chromatography–mass spectrometry, we analysed solvent extracts of fur surrounding the shoulder gland in the northern-shouldered bat, Sturnira parvidens to (i) characterise the chemical composition of shoulder gland secretions for the first time, and (ii) look for differences in chemical composition among and between adult males, sub-adult/juvenile males and adult females. Fur solvent extracts were analysed as liquids and also further extracted using headspace solid-phase microextraction to identify volatile components in the odour itself. Odour fingerprint analysis using non-metric multidimensional scaling plots and multivariate analysis revealed clear and significant differences (P < 0.001) between adult males vs both juvenile males and adult females. The chemical components of the shoulder gland secretion included terpenes and phenolics, together with alcohols and esters, most likely derived from the frugivorous diet of the bat. Many of the compounds identified were found exclusively or in elevated quantities among adult (reproductive) males compared with adult females and non-reproductive (juvenile) males. This strongly suggests a specific role in male–female attraction although a function in male–male competition and/or species recognition is also possible. creator: Chris G. Faulkes creator: J. Stephen Elmore creator: David A. Baines creator: Brock Fenton creator: Nancy B. Simmons creator: Elizabeth L. Clare uri: https://doi.org/10.7717/peerj.7734 license: https://creativecommons.org/licenses/by/4.0/ rights: © 2019 Faulkes et al.