The specimens came from Hunan, Guizhou and Fujian provinces. Before this investigation, eight euthyadin species in three genera had been recorded in China. Most known euthyadin mites inhabit streams and ponds, while relatively few occur at water margins, and many species have lacked clear habitat records. The study was the first focused investigation of water-margin habitats for these mites in China.

The researchers collected mites from moss or green algae that had been washed and soaked by stream water. Specimens were preserved in Koenike’s solution, and dissected material was sealed in gelatin mounting solution. External morphology was examined with optical microscopy and scanning electron microscopy, while measurements were reported in micrometres. Type material was deposited at the Institute of Entomology, Guizhou University in Guiyang.

Panisopsis (s. str.) lixunae was represented by an adult female holotype and seven paratypes from Hunan and Guizhou. The mites occupied moss on stones in shallow mountain streams, where the stones were partly exposed above the water and scoured by swift currents. Diagnostic features included an approximately inverted-trapezoidal median eye plate, large rounded dorsal plates, a short gnathosomal base and numerous lamellate setae on the ventral surfaces of the terminal segments of the third and fourth legs.

The three new Deuterothyas species were collected from green algae along the banks of rapid streams in subtropical evergreen broad-leaved forest in Fujian. Deuterothyas fulu was distinguished by small dorsal and lateral plates, a narrow second pair of genital flaps, and two thick terminal spines on the extended lateral ventral surface of the fifth segment of the fourth leg. Deuterothyas fujianensis had a porous thickening beneath the median eye plate.

Deuterothyas crescentis was distinguished by porous secondary sclerotization beneath the integument, which developed as the mites matured. In fully mature males, this structure extended from the frontal to the posterior margin of the idiosoma without enclosing the eye capsules, dorsoglandularia 1–4, ventroglandularia 4 or slit organs. In females, the secondary sclerotization grew from the median eye plate and dorsal-central plates 3–5 and extended outward laterally. It was not yet developed in newly emerged adults.

Comparison of optical and scanning electron micrographs showed that structures described as “porous dorsalia” in some Deuterothyas were actually secondary sclerotizations beneath the integument rather than plates on the idiosomal surface. These structures were generally larger and more complex in males than in females, although scanning electron micrographs showed no sex difference in the actual dorsal plates.

Deuterothyas fujianensis was separated from D. variabilis by the posterior position of D2 relative to Dc2, more angular third and fourth coxae, and a smaller second pair of genital flaps with fewer setae. The study was based on morphological examination of collected type material from selected southern Chinese localities; it did not measure population trends, ecological effects or the prevalence of the four species across China.

Subject of Research: Taxonomic description of four new Euthyadinae water mites from stream margins in southern China

Article Title: Four new species of Euthyadinae Viets, 1931 ( Acari , Hydrachnidia , Hydryphantidae ) living in water-margin habitats in southern China

Article References: Zhan, B.-X., Smit, H., Li, H.-T., Gu, X.-Y., & Guo, J.-J. (2026). Four new species of Euthyadinae Viets, 1931 (Acari, Hydrachnidia, Hydryphantidae) living in water-margin habitats in southern China. Zoosystematics and Evolution, 102(4), 911-941. https://doi.org/10.3897/zse.102.197692

Image Credits: AI Generated

DOI: 10.3897/zse.102.197692

Keywords: Euthyadinae, water mites, taxonomy, new species, southern China, stream margins, morphology, scanning electron microscopy, Hydryphantidae, Four, species, Viets

For the experimental series, the researchers produced biochar through controlled pyrolysis of sisal fibers and incorporated the particles into an epoxy matrix as filler. They then made five laminates containing zero, one, two, three or four layers of sisal mat using the hand lay-up method. Mechanical performance improved incrementally as the number of mat layers increased, with the three-layer formulation recording the highest reported values. The available abstract does not provide numerical results for all five formulations, so the size of the improvement between adjacent samples cannot be determined from the supplied evidence.

The three-layer composite’s elongation value of 5.50% was reported alongside its tensile and flexural strengths, but the abstract does not describe the deformation sequence, failure mode or test conditions. It likewise does not provide individual measurements, error bars or other statistical measures of variation. The study therefore establishes the strongest reported result within this laboratory series, but the supplied material does not show how reproducible that result would be across larger batches, different processing conditions or service environments.

Physical-property measurements showed density rising from 1.10 to 1.31 g/cm3 across the tested material series. At the same time, thermal conductivity decreased from 1.30 to 1.16 W/m K, which the researchers described as improved insulation. These changes were measured properties of the composites, not evidence of a quantified trade-off between reinforcement and heat transfer. The abstract also does not identify which individual formulation produced either endpoint, report measurement uncertainty or compare the thermal performance with conventional fiber-reinforced epoxy systems.

Scanning electron microscopy showed that the sisal-derived biochar was dispersed homogeneously and that adhesion between the sisal fiber and epoxy matrix was strong. The supplied source does not support additional conclusions about load transfer, interfacial defects or the causes of the measured mechanical behavior. By combining sisal fiber mats with particles made from the same plant fiber, the researchers developed a hybrid composite aimed at improving strength and thermal behavior while retaining a sustainability objective. However, the abstract reports no lifecycle assessment, comparison with other composite materials, recycling test or long-term durability measurement, so it does not demonstrate an end-to-end environmental advantage or suitability for a finished engineering structure.

Subject of Research: Laboratory characterization of sisal-fiber and sisal-biochar reinforced epoxy laminates

Article Title: Development and characterization of sustainable hybrid epoxy biocomposites reinforced with sisal fiber mats and sisal-derived biochar particles

Article References: Arunraja, K. M., Lavanya, R., Arunkumar, S., & Senthilkumar, V. (2026). Development and characterization of sustainable hybrid epoxy biocomposites reinforced with sisal fiber mats and sisal-derived biochar particles. Journal of Materials Science. https://doi.org/10.1007/s10853-026-13918-y

Image Credits: AI Generated

DOI: 10.1007/s10853-026-13918-y

Keywords: sisal fiber, biochar, epoxy composite, biocomposites, tensile strength, flexural strength, thermal conductivity, scanning electron microscopy, sustainable materials, Development, characterization, sustainable

The study combined light microscopy with scanning electron microscopy. It also provides the first detailed documentation of the marginal ridge, proximal and distal mantles and fibulae of T. calida, a species for which earlier electron micrographs had provided limited detail.

The authors collected a surface-sediment sample from the littoral zone of East Dongting Lake on 5 March 2023, at 29°19′7″N, 112°47′32″E and 39 m above sea level. The sample contained T. calida, T. dongtingensis and T. hunanensis. A second sample was collected on 24 March 2024 from mud sediments on stone surfaces in a riffle of the Yongle River, a tributary of the Xiang River, at 26°55′08″N, 113°35′55″E and 119 m above sea level. It contained T. calida and T. hunanensis. Slides were deposited in the Herbarium of Jishou University, Hunan, China.

Tryblionella calida had linear-lanceolate valves with wedge-shaped, slightly protruding apices and an almost flat valve surface. Among 17 measured valves, lengths ranged from 38–61 μm and widths from 8.6–10.6 μm. The axial sternum was absent, continuous transapical ribs numbered 15–17 per 10 μm and rectangular to square fibulae numbered 9–10 per 10 μm. Scanning electron microscopy showed a high marginal ridge with long slit-like fenestrae at its base and a smooth, plain upper margin. The distal mantle was shallow and unornamented, while the deep proximal mantle often concealed the fibulae.

The newly described T. dongtingensis was based on the holotype specimen deposited under slide number DIA2026002, with the type locality in East Dongting Lake. Its 30 measured valves were linear-lanceolate, 33–65 μm long and 10.3–12.1 μm wide. A longitudinal fold along the valve midline divided the valve face into two non-coplanar halves. Transapical ribs numbered 9–14 per 10 μm and fibulae numbered 6–9 per 10 μm. Some transapical ribs crossed the valve face continuously, whereas others ended at the central fold. The species had a high marginal ridge with long slit-like fenestrae, but its upper margin was undulate rather than plain.

Tryblionella hunanensis was represented by the holotype on slide DIA2026003 from the Yongle River. Across 31 measured valves, it had panduriform outlines with cuneate to acute apices, lengths of 37–53 μm and widths of 8.9–13.2 μm. Its valve face was slightly undulate, with 9–12 transapical ribs per 10 μm and 7–10 rectangular to square fibulae per 10 μm. Electron micrographs revealed dense silica granules, four to seven longitudinal grooves in the raphe-canal wall on the valve side, and a high marginal ridge with a distinctly lobed upper margin. Unlike the ridges of T. calida and T. dongtingensis, its basal portion lacked long slit-like fenestrae and instead had a row of pores at the junction with the distal mantle.

Field measurements at the Dongting Lake locality gave conductivity of 494 ± 0.9 μS cm−1, pH of 8.4 ± 0.06 and water temperature of 27.8 ± 0.3 °C. The authors associated the environmental measurements and associated diatom assemblage with alkaline and mesotrophic to eutrophic conditions. At the Yongle River locality, conductivity was 111.7 ± 0.8 μS cm−1, pH was 7.6 ± 0.04 and water temperature was 22.3 ± 0.3 °C; the associated assemblage and measurements suggested alkaline and mesotrophic conditions. T. dongtingensis was reported only from its type locality, while T. hunanensis was reported from the Yongle River and East Dongting Lake.

Although the three species can coexist in East Dongting Lake and have overlapping valve dimensions, the study distinguished them through combinations of valve form, surface undulation, rib and fibula density, raphe-canal structure and marginal-ridge architecture. T. dongtingensis was characterized by its central longitudinal fold and undulate ridge margin, while T. hunanensis combined a panduriform valve, grooved raphe-canal wall, silica granules and lobed ridge margin. The paper placed all three in a morphological group characterized by a more or less undulate valve face, transapical ribs, uniseriate striae with rounded, rimmed inner areolar openings, bar-like ribs along the raphe-canal wall, a marginal ridge and squat or apically elongated fibulae.

The observations come from two collected samples and detailed microscopy of selected specimens rather than a survey of population abundance, seasonal variation or broad geographic distribution. The limited collection localities mean that the reported environmental associations and known distributions should not be treated as comprehensive. The authors also noted that the monophyly of a proposed group around T. calida remains unresolved: the study found that the fibulae of T. calida are non-perforated, contrary to the character state used in an earlier morphological consensus tree.

Subject of Research: Taxonomic and ultrastructural study of freshwater Tryblionella diatoms in Hunan, China

Article Title: Ultrastructure of three species of Tryblionella ( Bacillariophyceae ) found in freshwater habitats in Hunan Province, China, including descriptions of two new species

Article References: Ma, Y.-L., Yu, C.-P., Liu, B., Rioual, P., Ma, Y.-D., & Jiang, X.-Y. (2026). Ultrastructure of three species of Tryblionella (Bacillariophyceae) found in freshwater habitats in Hunan Province, China, including descriptions of two new species. PhytoKeys, 278, 259-277. https://doi.org/10.3897/phytokeys.278.204336

Image Credits: AI Generated

DOI: 10.3897/phytokeys.278.204336

Keywords: Tryblionella, diatom taxonomy, freshwater diatoms, Hunan Province, Dongting Lake, Yongle River, scanning electron microscopy, new species, valve ultrastructure, Ultrastructure, three, species

The new species were established through detailed examination of their external anatomy and male reproductive structures, known as gonopods. Specimens were collected in July 2025 and preserved in 90% ethanol. Researchers examined them with a Nikon SMZ800N stereomicroscope, dissected the gonopods, photographed structures at different focal depths with a Sony A6000 camera, and assembled the images using Helicon Focus 7.0 and Adobe Photoshop CS6. Scanning electron microscopy was also used.

The type series of H. caobang came from Truong Ha commune on the way to Coc Po Cave. It comprised one male holotype, one male paratype and five female paratypes: two females deposited at the Institute of Ecology and Biological Resources in Hanoi and three females at the Department of Entomology at Virginia Tech. The male holotype measured 25.1 mm in body length, with prozona and metazona widths of 1.87 mm and 2.27 mm, respectively. Females ranged from 28.0 to 29.2 mm in body length.

H. caobang is generally black, with yellow middle portions of the metaterga and paraterga, yellowish-brown legs and sterna, and black antennae. Its diagnostic features include a highly elevated, coniform process between the coxae of the fourth pair of legs on sternum 5, a long and slender gonopod femorite, and a strongly spiraled solenophore that is broad apically and bears spiniform processes on its lateral and mesal sides. Although its apical solenophore resembles that of H. montana, the Vietnamese species lacks the prominent solenophore tooth present in H. montana. The specimens were found beneath leaf litter in moist limestone forest.

The second species, H. vast, was represented by one male holotype collected at Thang Hen Lake in limestone forest on 15 July 2025, one male paratype with the same collection data, and seven additional paratypes from Pia Oac-Pia Den National Park. The holotype was 26.9 mm long, with prozona and metazona widths of 2.14 mm and 2.48 mm. Male paratypes measured 24.9–26.05 mm, while the reported female was 28.5 mm long. The species was collected beneath leaf litter in moist limestone forest at an elevation of about 1,000 metres above sea level.

H. vast is generally dark brown, with yellowish-brown pleura, pale-yellow sterna and legs, and brown antennae except for the distal half of antennomere 6 and antennomere 7, which are black. It has a highly elevated, rounded process between the fourth coxae on sternum 5. Its gonopods have a long, slender femorite and a spiraled solenophore with a long acute process and a strongly bifid apical tip. These features distinguish it from H. caobang, which has a broader apical solenophore bearing two spiniform processes.

For DNA barcoding, the researchers extracted genomic DNA with Qiagen DNeasy Blood and Tissue Kits. They amplified a 680-base-pair fragment of the mitochondrial cytochrome c oxidase subunit I gene with the LCO1490 and HCO2198 primers and a 500-base-pair fragment of the 16S ribosomal RNA gene with either the 16Sa/16Sb or 16S-1F19 primer set. Two-microlitre portions of amplification products were screened by electrophoresis in 1% agarose-TAE, then sent to GenLab in Vietnam for purification and sequencing. The sequences were checked through an NCBI BLAST search and deposited in GenBank.

Both species yielded 16S rRNA barcodes, but the COI barcode from H. vast failed to sequence. The H. caobang sequences were deposited under accession numbers QB104726 for COI and QB104679 for 16S rRNA, while the H. vast 16S rRNA sequence was deposited as QB104680. BLAST comparisons reported genetic similarities of 85.63% for H. caobang and 85.51% for H. vast with Sellanucheza variata. Because no Hedinomorpha sequences were then available in NCBI, direct genetic comparisons with members of the genus were not possible.

Both Vietnamese species resemble H. reducta from Sichuan, China, in having poorly developed paraterga, long and slender gonopod femorites without a mesal groove, and generally comparable gonopod configurations. They differ from that species in body width and in the form of the process at the base of the solenophore: H. reducta has an unciform process, whereas the Vietnamese species have a large spine. Their morphology does not fully match the typical diagnosis of Hedinomorpha, and their closest BLAST matches were Sellanucheza species. Nevertheless, the authors retained both in Hedinomorpha because the available molecular and morphological evidence did not justify transferring them to Sellanucheza or erecting a new genus. The records confirm the genus in northern Vietnam while leaving questions about the placement of these unusual species open.

Subject of Research: Taxonomic description of two new Hedinomorpha millipede species from northern Vietnam using morphology and mitochondrial DNA barcoding

Article Title: First records of the millipede genus Hedinomorpha Verhoeff, 1934 ( Diplopoda , Polydesmida , Paradoxosomatidae ) from Vietnam, with descriptions of two new species

Article References: Nguyen, T.-A. T., Marek, P. E., & Nguyen, A. D. (2026). First records of the millipede genus Hedinomorpha Verhoeff, 1934 (Diplopoda, Polydesmida, Paradoxosomatidae) from Vietnam, with descriptions of two new species. Zoosystematics and Evolution, 102(5), 1221-1232. https://doi.org/10.3897/zse.102.208437

Image Credits: AI Generated

DOI: 10.3897/zse.102.208437

Keywords: Hedinomorpha, millipedes, Vietnam, Cao Bang Province, new species, taxonomy, DNA barcoding, morphology, Paradoxosomatidae, zoology, First, records

Researchers monitored degradation using gravimetric analysis, scanning electron microscopy and Fourier-transform infrared spectroscopy. The electron microscopy observations described progressive structural deterioration in both polymers. PET samples developed severe fracturing and flaking, while PS blocks showed large hollow cavities that the authors said contributed to loss of structural integrity. These observations were reported for the laboratory samples and do not establish how the process would perform in other settings.

The abstract also reported changes in the PET infrared spectra during the third and fourth weeks, particularly in the 1000–1700 cm−1 wave-number region. The researchers associated these changes with loss of polymer integrity and fragmentation. For PS, they said early formation of hydroxy and hydroperoxide groups was indicated by broadening of the peak at 3400 cm−1 and linked this pattern to the accelerated onset of biodegradation. The reported measurements therefore point to surface deterioration and changes in the tested polymer samples, but the abstract does not provide enough detail to quantify all analytical differences or determine their statistical uncertainty.

This was a controlled laboratory experiment rather than a field trial, and the available abstract does not report replication, sample size, statistical testing, complete controls, or the extent to which other microorganisms or environmental conditions affected the results. It also does not establish that the observed weight changes represent complete mineralization. The findings are limited to the tested PET sheets, PS blocks, culture conditions, UV pretreatment and four-week observation period; broader effects on plastic-waste management were not evaluated in the reported experiment.

Subject of Research: Laboratory assessment of Pseudomonas fluorescens degradation of UV-pretreated PET and polystyrene

Article Title: Pseudomonas fluorescens mediated plastic degradation and influence of UV pretreatment

Article References: Manoj, N., A., M., S., B., P., D., Martin, A. A., & Ashraf, S. (2026). Pseudomonas fluorescens mediated plastic degradation and influence of UV pretreatment. Discover Sustainability. https://doi.org/10.1007/s43621-026-04894-z

Image Credits: AI Generated

DOI: 10.1007/s43621-026-04894-z

Keywords: Pseudomonas fluorescens, plastic biodegradation, polyethylene terephthalate, polystyrene, UV pretreatment, gravimetric analysis, scanning electron microscopy, Fourier-transform infrared spectroscopy, Pseudomonas, fluorescens, mediated, plastic

The synonymization rests on close examination of the type material of S. razalii and comparison with specimens of F. dubius in Malaysian collections and photographs of the latter species’ type material available through the Orthoptera Species File. The authors detected no morphological differences supporting treatment of the two names as separate species. Falconius can be distinguished from other scelimenine genera by a swollen hind tarsus in females, a relatively stout head, a frontal costa that forks relatively close to the fastigium, anterior eye margins raised slightly above the fastigium, and relatively high positions of the paired ocelli and antennal grooves in relation to the compound eyes. The study also corrected an incorrect type-material listing in an earlier thesis and presented the museum records as the first official record of F. dubius from Peninsular Malaysia. Material reported as S. razalii from Pakistan was not examined, so its identity remains uncertain and requires re-examination.

The reappraisal also corrected numerous earlier identifications of S. gombakensis. Some Malaysian specimens had been labeled Scelimena producta, a species described from Java whose body coloration can resemble that of S. gombakensis. The two can be distinguished by features of the pronotum and hind femora: S. producta has pointed tubercles at the pronotal humeral angles and numerous clearly visible teeth on the ventral side of the hind femora, whereas S. gombakensis has rounded humeral angles and only two small teeth. Re-examination of museum holdings showed that the species had been present in collections for decades without being recognized as distinct from S. producta. This correction produced locality records in Selangor, Penang, Pahang, Perak, Kelantan, Negeri Sembilan, Johor and Terengganu, supplementing the physical and verified iNaturalist records assembled by the study.

The revision shows that S. gombakensis is not as restricted as an earlier account suggested. When it was described in 2018, the species was known from Sungai Gombak in the Gombak Catchment of Selangor. Museum material and verified citizen-science observations now place it across much of Peninsular Malaysia, especially along the west coast. The study included iNaturalist records available before its submission on 29 August 2022, with observers’ identifications checked by the authors. One record from Waeng district in Narathiwat, southern Thailand, close to the Malaysian border, is reported as the first official record outside Peninsular Malaysia and the first for Thailand. The authors did not directly compare S. gombakensis with Scelimena discalis specimens from Thailand because the physical specimens were inaccessible and molecular and suitable online data were lacking. They note that some Thai material identified as S. discalis may warrant renewed comparison.

Field observations at the Ulu Gombak Field Study Center indicate that S. gombakensis occupies a cool, humid and shaded habitat in lowland secondary rainforest. Individuals perch on river rocks near flowing water and tend to gather close to the surface, where the stream environment is humid. Lichen and moss are reported as the species’ food source. Juveniles were more often observed near the water than adults. The authors associate this pattern with two characteristics of immature individuals: their exoskeletons may make them more susceptible to desiccation, and they are less agile and unable to fly. Remaining near the water may therefore increase a juvenile’s chance of escaping a predator by diving. Adults and juveniles can occupy the same rock, but the egg-laying site of S. gombakensis remains unknown. Sand along riverbanks has been suggested as a possible egg-laying location for other Scelimena species.

Scanning electron micrographs revealed microscopic features on the hind tibia and first tarsal segment of S. gombakensis. The first tarsal segment is laterally compressed along its entire length, while both the tarsal segment and tibia carry serrations along their lateral edges. The authors suggest that compression may provide a wider surface for paddling and aid propulsion during swimming. Because the claws lack an arolium, the adhesive pad normally associated with them, the tarsal serrations may help the insect grip wet, slippery and porous rock surfaces. The serrations could also have a hydrodynamic function by reducing drag as the legs move underwater, limiting vortex formation and potentially making swimming more energy-efficient. Their orientation parallel to the direction of water movement is consistent with that possibility. These remain functional hypotheses based on morphology, not results from direct measurements of swimming performance, grip strength or energy use.

Behavioral observations suggest that S. gombakensis uses both its hind legs and hindwings for navigation and escape. The species was observed flying long distances and maneuvering effectively in flight, contrasting with the related S. songkrana from Thailand, which seldom flies and relies more often on jumping. Scelimena melli from China has been described as behaving similarly to S. gombakensis, although it can leap at least 10 metres. Mating behavior in S. gombakensis was consistent with observations of other Scelimena species, with the male positioning himself on top of the female. The authors also propose that S. gombakensis may disperse passively with water after diving, potentially connecting its distribution to large flowing bodies of water. That transport mechanism was inferred from the ecology and behavior rather than demonstrated directly.

Examination of the large museum series also revealed substantial variation in S. gombakensis. Adult males measured 18.0–24.0 millimetres, while females measured 24.0–31.0 millimetres. Nymphs broadly resemble adults in coloration and general appearance, although their shorter pronotum makes them readily distinguishable from other Tetrigidae in Peninsular Malaysia. One living individual had a brown body with orange markings rather than the more typical dark green coloration with yellow markings. The authors could not determine whether this unusual appearance was recessive or caused by an infection. Pinned specimens also faded from dark green with yellow markings toward brown, and older examples were generally more degraded than recent ones. Uneven fading among specimens collected around the same time and stored under similar conditions suggests that conditions before pinning, including collection, euthanization, pinning and preservation practices, may affect color retention, but information about those historical conditions was unavailable.

Malaysian Tetrigidae remain incompletely studied, with earlier publications concentrating largely on taxonomy, species descriptions and occurrence records. The present study combined revision of historical museum material, author-verified citizen-science observations, daytime field observations of behavior and food preference, and scanning electron microscopy of preserved legs. These approaches changed both the taxonomic arrangement and the known distribution of the genus. Type examination showed that S. razalii should be merged with F. dubius, while re-identification of older specimens and compilation of observation records showed that S. gombakensis extends well beyond its original Selangor locality and has been recorded in southern Thailand. The study also documented its association with humid river-rock habitat and described leg features consistent with possible swimming and gripping functions. Its conclusions remain bounded by the material available: the Pakistani S. razalii specimens were not reassessed, Thai S. discalis material could not be compared directly, and the proposed functions of the leg structures and water-mediated dispersal were not tested experimentally.

Subject of Research: Taxonomy, distribution, ecology and hind-leg morphology of Peninsular Malaysian Scelimena grasshoppers

Article Title: Towards a better understanding of the genus Scelimena ( Orthoptera , Tetrigidae , Scelimeninae ): New insights and notes on the taxonomy, ecology, and physiology of the genus in Peninsular Malaysia

Article References: Muhammad, A. A., Deranja, M., Adžić, K., & Abdullah, N. A. (2023). Towards a better understanding of the genus Scelimena (Orthoptera, Tetrigidae, Scelimeninae): New insights and notes on the taxonomy, ecology, and physiology of the genus in Peninsular Malaysia. Journal of Orthoptera Research, 32(1), 55-62. https://doi.org/10.3897/jor.32.91153

Image Credits: AI Generated

DOI: 10.3897/jor.32.91153

Keywords: Scelimena gombakensis, Falconius dubius, pygmy grasshoppers, Tetrigidae, Peninsular Malaysia, taxonomic revision, citizen science, scanning electron microscopy, aquatic adaptations, species distribution, Towards, better

The researchers examined caddisflies in the Rhyacophilidae, Glossosomatidae, Hydroptilidae, Ptilocolepidae, Hydrobiosidae, Philopotamidae and Stenopsychidae. Most specimens came from the collection of the Department of Entomology at St. Petersburg State University and had been preserved in 70% ethanol.

The sample spanned multiple genera and included males and females for some species. Two basal Lepidoptera, Micropterix maschukella and Eriocrania cicatricella, were included for comparison. This was a comparative morphology study based on the external structure and arrangement of receptors; it did not measure neural activity or test behavior experimentally.

For scanning electron microscopy, the researchers removed the palps or heads, dried them, mounted them on specimen holders and coated them with 20 nm of gold. They used three scanning electron microscopes and counted and measured sensilla from the resulting micrographs with ImageJ 1.52r. The insects had three-segmented labial palps and five-segmented maxillary palps, matching the segment numbers observed in the two comparison moths.

Most palp surfaces were covered with microtrichia, small processes regarded by the study as non-innervated and therefore non-sensory. Areas carrying groups of sensilla often had thinner, more flexible cuticle and underwent substantial deformation in dried preparations. Transverse cuticular folds on the terminal segments of Philopotamidae and Stenopsychidae produced the annulated appearance associated with Annulipalpia.

Pointed long trichoid sensilla occurred on the maxillary and labial palps of every examined caddisfly and were distributed nonspecifically across the segments. These structures were flattened and elongated, with acute tips, longitudinal ridges and dorsal serration. The serration was especially pronounced in Hydroptilidae.

Long trichoid sensilla detached readily and left elongated sockets. Although some may be scales without a sensory role, the researchers classified them as sensory until histological work can distinguish their innervation. In the basal moths, pointed trichoid sensilla occurred alongside ordinary scales and broader, scale-shaped structures with deep longitudinal grooves.

Blunt chaetoid sensilla were also present on all segments of both pairs of palps in every caddisfly species examined. These hair-shaped receptors had a rounded cross-section, longitudinal striation and a blunt tip, and occurred in long, heavily sclerotized and short, pale forms. Long blunt chaetoid sensilla formed dense groups on the medial surfaces of the first and second maxillary palp segments in many species.

Their sockets included rounded or bean-shaped forms, sometimes with raised walls that restricted movement to a short range in one direction. Such groups were not formed in Hydrobiosidae, in Padunia adelungi or in Agraylea sexmaculata, while species of Chimarra restricted them to the distal part of the second maxillary segment. Short, weakly sclerotized blunt chaetoid sensilla occurred throughout the palps and were particularly dense on the medial and ventral surfaces of the third through fifth segments.

Campaniform sensilla had a thin flat or domed central area surrounded by an elevated cuticular ring. They occurred sporadically on the first labial and second maxillary palp segments, singly or in groups of up to five, and were usually 2.5 to 5 micrometres in diameter. Mushroom-like pseudoplacoid sensilla had a rounded or flattened cap on a thick, fixed stem, with pore-bearing grooves radiating from the centre of the apical surface.

They were present in all sampled Philopotamidae and Glossosomatidae and in two Rhyacophila species, occurring on both pairs of palps and tending to be more numerous dorsally. Petaloid sensilla occurred in all but four studied species. Some were flattened, with a wide plate attached almost at right angles to a slender stem, while those in Rhyacophilidae, Hydrobiosidae and Chimarra were elongated, curved and pointed.

Groups of petaloid sensilla formed specialized sensory fields in 19 caddisfly species. Labial fields were located on the third segment, while maxillary fields occurred on either the third or fifth segment in seven species. The fields were generally oval or strip-shaped, but some occupied approximately half the surface of a segment.

Their orientation varied among species: they were ventral in several Glossosomatidae, Hydroptilidae and other groups, dorsal in Rhyacophilidae and Hydrobiosidae, medial in Chimarra thienemanni and Stenopsyche marmorata, and lateral in Chimarra okuihorum. Maxillary fields contained from 21 petaloid sensilla in C. okuihorum to 460 in C. thienemanni. Labial fields ranged from seven in Glossosoma unguiculatum to 140 in A. sexmaculata.

The moth M. maschukella had a comparable subapical depression containing 15 to 20 petaloid sensilla on its third labial palp segment. Most caddisfly palps also bore narrow apical sensory complexes containing thick basiconic sensilla. These smooth, poreless, cone-shaped projections were restricted to the specialized complexes and absent from the surrounding microtrichial surface.

The central sensillum was usually longer than 3 micrometres, while two to five lateral sensilla were generally below 2 micrometres. The complexes occurred in most studied species but were absent from Chimarra, several Glossosomatidae, most Hydrobiosidae and the examined Hydroptilidae. Taschorema apobamum retained them on its labial palps.

Both comparison moths possessed apical complexes on the fifth maxillary segment, although their boundaries with the remaining segment surface differed from those in caddisflies. A seventh receptor type, thin basiconic sensilla, was found only in Glossosoma altaicum, where it occurred on the fourth and fifth maxillary segments and measured 6 to 12 micrometres. Comparisons with previously described antennal receptors showed that caddisfly palps contained a reduced and altered version of the order’s sensory repertoire.

Several pseudoplacoid subtypes found on antennae were not found on palps, nor were thin curved trichoid sensilla and Böhm’s bristles. Conversely, the thick basiconic and petaloid sensilla characteristic of the palps were absent from antennae. Although the main receptor types, numbers and broad distributions were similar among the basal families, the study found variations at genus, subfamily and species levels.

Extensive pseudoplacoid coverage may characterize Philopotamidae, but it cannot diagnose Annulipalpia as a whole because Stenopsychidae lacked those receptors. Similarly, differences in petaloid sensilla, sensory fields and apical complexes generally provided information at lower taxonomic levels rather than across families or the phylogeny. From these distributions, the authors proposed a hypothetical ground plan for ancestral caddisfly palps with six principal sensilla types: long trichoid, blunt chaetoid, campaniform, mushroom-like pseudoplacoid, petaloid and thick basiconic.

The reconstructed maxillary palp included shortened basal segments bearing enlarged medial chaetoid sensilla, elongated middle and terminal segments with trichoid and pale chaetoid receptors, a dorsolateral field of petaloid sensilla, and a narrow apical sensory complex. The labial ground plan was similar but lacked the grouped stout chaetoid sensilla and had a dorsal field of petaloid sensilla on its third segment. Comparisons with the two basal moths and with Mecoptera led the researchers to interpret diverse receptor types, sensory fields and modified apical zones as likely ancestral features of Amphiesmenoptera, the group containing caddisflies and moths.

They proposed enlarged basal chaetoid sensilla and a distinct narrow apical zone as characteristic caddisfly traits. The functional roles of these receptors were not directly established because the study measured morphology rather than physiological responses or behavior. The authors described the movable blunt chaetoid sensilla as possible contact chemomechanoreceptors and the apical complexes as possible sites of localized gustatory input.

Petaloid sensilla were proposed as candidates for receiving carbon dioxide, plant volatiles or pheromones because comparable moth structures have those roles, but no physiological tests were conducted on caddisfly palps. Pseudoplacoid sensilla were also discussed as possible humidity receptors, conditional on unresolved questions about their neuronal innervation. The main demonstrated result is therefore structural: basal caddisfly families share a core arrangement of palp sensilla, while evolutionary change is most evident in the reduction, modification or redistribution of apical complexes, pseudoplacoid receptors, basal chaetoid groups and sensory fields.

Subject of Research: Comparative external morphology of mouthpart sensilla across seven basal caddisfly families

Article Title: Mouthpart palp sensilla of basal Trichoptera families

Article References: Diiak, K. T. A., Ivanov, V. D., Melnitsky, S. I., Valuyskiy, M. Y., & Puyto, A. A. (2023). Mouthpart palp sensilla of basal Trichoptera families. Deutsche Entomologische Zeitschrift, 70(1), 55-68. https://doi.org/10.3897/dez.70.98752

Image Credits: AI Generated

DOI: 10.3897/dez.70.98752

Keywords: caddisflies, Trichoptera, mouthpart palps, sensilla, scanning electron microscopy, comparative morphology, insect sensory systems, Lepidoptera, evolutionary biology, Mouthpart, palp, basal

The investigation focused on the Selaginella valdepilosa group, a set of morphologically similar taxa defined by a suite of overlapping features. Members generally have a ribbon-like or leafy liverwort- to moss-like habit, creeping stems, filiform rhizophores, small lateral leaves that vary from ovate to elliptic, and light yellow, yellow or cream megaspores. Because these traits overlap extensively among species, their boundaries have historically been unstable, particularly where original collections were scarce and type material received limited study. S. brachyclada has at times been treated as a synonym of S. porelloides or S. rhodostachya, while S. rhodostachya itself has been interpreted broadly enough to include several distinct taxa.

To reassess the group, the authors examined the types of S. brachyclada, S. brevispicata, S. diminutifolia, S. rhodostachya, S. valdepilosa and S. valdepilosa subsp. tricholoma. They also studied additional collections from the Guayana Highlands and Venezuelan tepuis, checked herbarium specimens and digital images held by numerous institutions, and consulted records through the PteridoPortal. Scanning electron microscopy was used to inspect minute structures on leaves and spores, including epidermal cells, stomata, marginal idioblasts, hairs and spore surfaces. The combined evidence was intended to establish the species circumscriptions directly from type material rather than rely on the historical names attached to later collections.

Type evidence clarified the tangled naming history. S. brachyclada was described from a collection made in Guyana in May 1887, represented by G.S. Jenman 1481. Jenman subsequently used the same gathering to describe S. diminutifolia on July 23 that year, so the earlier epithet brachyclada has priority. S. rhodostachya had been described from an earlier collection made on the Venezuelan side of Mount Roraima by E.F. im Thurn. Its correct type citation is im Thurn s.n.; numbered labels attached to isotypes at the Natural History Museum and Smithsonian Institution were interpreted as errors involving positions or numbers in Baker’s earlier botanical synopsis rather than genuine collector numbers. The revision also corrected the type collection of S. valdepilosa subsp. tricholoma from 58016 to 58916 after checking Steyermark’s collection record.

The reinstated S. brachyclada can be distinguished from S. rhodostachya through leaf shape, margins, apices and microscopic anatomy. Its median leaves are ovate, broadly ovate, ovate-deltate or cordate, with rounded to subcordate bases and usually one to four short, stiff, tooth-like hairs at the apex. Its lateral leaves on main stems are ovate-deltate with subcordate bases, whereas those of typical S. rhodostachya are elliptic to elliptic-ovate with rounded bases. The axillary leaves of S. brachyclada are ovate-deltate, subcordate or ovate-lanceolate, and its leaf margins are only sparsely denticulate. It also differs from the form formerly assigned to S. valdepilosa subsp. tricholoma, whose leaf margins bear conspicuous long cilia.

Scanning electron microscopy supported the separation by revealing differences in cell structure and arrangement. On the upper surface of the median leaf of S. brachyclada, the midrib is prominently raised along its distal one-half to three-quarters, with stomata arranged in one to four rows along the keel and additional stomata near the outer margins. Its lateral leaves carry bands of elongated, straight-walled, papillate idioblasts along the margins. Lower surfaces contain elongate, sinuate-walled, laevigate cells together with scattered papillate idioblasts. Typical S. rhodostachya instead bears elliptic to elliptic-ovate median leaves with conspicuously keeled midribs, narrow hyaline margins one or two idioblast cells wide, and apices that may be obtuse or rounded or carry either short projections or two long, divergent cilia.

The revision also changed the proposed relationship between S. microdonta and S. brachyclada. Previous work had suggested that S. microdonta was closely related to S. brachyclada, but examination of the relevant types and additional specimens placed S. microdonta closer to S. cardiophylla, S. hemicardia and S. rostrata within the Selaginella microdonta group, which the authors renamed the S. valdepilosa group. The review of historical sheets also found that some collections had been divided incorrectly or treated as a single species. Several were mixed gatherings containing S. rhodostachya together with S. vernicosa, while material cited by earlier researchers as S. rhodostachya from Kaieteur was identified as S. sandwithii.

Selaginella brachyclada grows terrestrially or on rock in moist settings, including ledges and seepage surfaces near waterfalls, tropical savanna, gallery forest and riparian forest. It is confirmed from its type locality at the foot of Kaieteur Falls in Guyana and from five collections in the Gran Sabana region of Bolívar State, Venezuela, at elevations of 995–1,200 metres. The authors considered occurrence in neighboring Roraima in northern Brazil likely because suitable habitat is continuous, but stressed that Brazilian presence has not been confirmed. S. rhodostachya occupies muddy soil, rock crevices and the bases of wet bluffs in shrubland and forest at 1,350–2,800 metres. It has been recorded from the Mazaruni-Potaro region of Guyana, Amazonas and Bolívar states in Venezuela, and Roraima in Brazil.

The authors also applied IUCN assessment standards to the revised geographic records, using mapped occurrences and a recommended two-kilometre grid. S. brachyclada is known from only six collections: its type from Kaieteur National Park in Guyana and five Venezuelan collections from Gran Sabana, including sites in or near Canaima National Park. Its estimated extent of occurrence is 4,128.942 square kilometres, but its area of occupancy is only 20 square kilometres. It was assessed as Endangered under Criterion B, specifically B1ab(iii)+B2ab(iii), because of its restricted distribution and continuing decline in habitat quality. Human-ignited fires associated with shifting cultivation and hunting, as well as informal and often illegal gold mining, were identified as threats. S. rhodostachya has a larger estimated extent of occurrence of 21,005.349 square kilometres but an area of occupancy of 28 square kilometres. The authors recommended a preliminary Vulnerable assessment under Criterion B2ab(iii), citing mining, logging, agriculture and infrastructure development as continuing pressures in parts of its range.

Subject of Research: Taxonomic revision and conservation reassessment of Selaginella brachyclada and S. rhodostachya

Article Title: Selaginella brachyclada reinstated from synonymy under S. rhodostachya ( Lycopodiopsida , Selaginellaceae ), with updated descriptions of both taxa

Article References: Valdespino, I. A., & López, C. A. (2026). Selaginella brachyclada reinstated from synonymy under S. rhodostachya (Lycopodiopsida, Selaginellaceae), with updated descriptions of both taxa. PhytoKeys, 274, 303-320. https://doi.org/10.3897/phytokeys.274.190998

Image Credits: AI Generated

DOI: 10.3897/phytokeys.274.190998

Keywords: Selaginella brachyclada, Selaginella rhodostachya, plant taxonomy, species reinstatement, herbarium specimens, scanning electron microscopy, Guayana Highlands, tepuis, species conservation, IUCN assessment, type specimens, leaf morphology

The observations provide additional characters for larval identification and document an exception to the previously reported mature-larva mandible form of Notodontidae, although the proposed links between particular structures and feeding or cocoon-building behaviors were not tested directly in feeding experiments. The species examined belong to a large family of Lepidoptera comprising approximately 3,800 recognized species in 734 genera worldwide. Its larvae are commonly called prominents and are recognized by relatively large head capsules and modified anal prolegs.

The caterpillars studied were all herbivorous and fed on leaves. The authors used these known host associations and life-history observations as context for comparing mouthpart form. The work was a comparative morphological study of laboratory-reared final-instar larvae, not a field test of performance on different plants or a broad survey of all Notodontidae species.

For the microscopy, adult females were collected under light traps, and fertilized eggs were maintained at 26 ± 1 °C with moist absorbent cotton. After emergence, the larvae received fresh leaves of their respective host plants and were photographed with a digital camera. Five final-instar individuals of each species were dissected, dehydrated in a graded ethanol series, transferred to tertiary butanol, freeze-dried for three hours and coated with gold.

They were then examined with a Hitachi S-3400N scanning electron microscope at 5 kV. All six species had the mandibulate arrangement of a labrum, a pair of mandibles and a maxilla-labial complex, but details of their shapes, setae, sensilla and silk-producing spinnerets differed. One conspicuous feature was shared across all six species.

The maxillae each possessed an elongate, sometimes hairy or apparently hollow maxillary sac on the inner surface of the galea. Such structures had previously been called stipital lobes and had been reported as diagnostic features of Notodontidae. Electron microscopy showed that the structures were internally hollow, while their position made placement on the stipes difficult to establish.

On that basis, the authors proposed that “maxillary sac” was the more appropriate term. They also suggested that the sacs might form seals between the mandibles and maxillae and help retain leaf tissue in the oral cavity, but that functional interpretation was not verified by the study. The shared presence of the sacs was an observed result; the name change and proposed sealing role were the authors’ interpretation.

N. davidi supplied the strongest departure from the pattern reported for the other five mature larvae. Its heavily sclerotized mandibles each carried six blunt dentitions on the distal margin, whereas the cutting edges of the other species were smooth. The finding was notable because Notodontidae larvae had previously been described as having serrate mandibles in the first instar but smooth mandibles in later stages.

The toothed mandibles of mature N. davidi were also similar to those reported for stem-chewing Sericinus montela larvae and polyphagous Spodoptera exigua larvae. The authors proposed that the teeth might be related to feeding on rough or wrinkled tissues of U. pumila, but the study did not directly measure feeding, test the elm leaves against alternative foods or establish the evolutionary cause of the condition. The front of the mouth also showed a suite of distinctions among species.

E. cristata, P. assimilis and F. furcula had V-shaped labral notches. F. ocypete had a much deeper central split, with two lateral lobes overlapping in the middle, while N. davidi had a shallow notch that did not extend to the center. C. erminea possessed a longitudinal central notch.

Every species had six pairs of labral setae, but their relative lengths and positions differed. The epipharynx carried sensilla chaetica, digitiform sensilla and epipharyngeal sensilla in differing numbers and arrangements. For example, E. cristata and P. assimilis had three pairs of sensilla chaetica, whereas F. ocypete had two pairs of similar length.

These characters expand the set of observable traits available for distinguishing the final-instar larvae, although the paper did not test how the differences affect the detection or handling of food. The caterpillars’ feeding behavior changed between the first and final instars. Newly hatched larvae were observed chewing the ventral surfaces of host leaves, while mature larvae usually bit leaf edges.

Mature E. cristata, F. ocypete and P. assimilis held onto twigs and leaves while feeding. P. assimilis was also unusual among the six species because its larvae lived gregariously; the other five were solitary. These observations were accompanied by specific life-history data.

When fully grown, E. cristata, F. ocypete, P. assimilis and N. davidi built cocoons in soil. C. erminea and F. furcula instead secreted thickened cocoons covering tree bark. The pupation locations and cocoon-building behaviors were therefore known parts of the study’s record, making it possible to compare them with spinneret structure without claiming that the morphology alone established the behavior.

Spinnerets showed several distinct forms. E. cristata had a generally tubular spinneret that tapered toward its apex and was longitudinally depressed along the dorsal distal surface. F. ocypete had a dorsoventrally flattened spinneret with a slightly separated distal opening.

P. assimilis and N. davidi likewise had dorsoventrally depressed distal openings, although their overall proportions differed. C. erminea had a short, dorsoventrally depressed spinneret with a widely separated opening, while F. furcula had a distinct broad, flat, lamellar spinneret. The four species that usually pupated in soil had longitudinally or dorsoventrally depressed tubular forms, whereas the two bark-associated species had broader or more flattened forms.

The authors considered the differences likely related to silk secretion or cocoon-spinning behavior, consistent with earlier observations, but no mechanical analysis of silk or controlled comparison of cocoon construction was performed. The study also placed the six species in relation to reported mouthpart patterns in other lepidopteran larvae. Smooth cutting edges occur in some leaf-feeding caterpillars, whereas dentate or combined cutting edges and cusps have been recorded in other groups.

The mature N. davidi mandibles added a clearly documented exception within Notodontidae. Elsewhere, F. ocypete was distinctive not only for its deeply divided labrum but also for the positions and lengths of its labral setae and its two pairs of epipharyngeal sensilla chaetica. The authors suggested that this combination might be taxonomically informative or associated with unusual biology, while emphasizing that further observations were required.

Similarly, the correspondence between spinneret form and pupation site was an association across six species, not evidence that changing a spinneret would cause a particular cocoon or pupation behavior. Overall, the comparison demonstrates that detailed final-instar mouthpart anatomy differs substantially even among caterpillars that share a family and a broad leaf-feeding lifestyle. It records a shared maxillary-sac structure, documents the unusual mature mandibles of N. davidi, and separates labral, sensory and spinneret characters that can be evaluated in taxonomic work.

The study’s strongest conclusions are morphological: these structures can be observed and compared, and they differ among species in measurable ways. Its ecological suggestions remain provisional because only six species were examined, the larvae were laboratory-reared, and the proposed relationships among mandible teeth, leaf tissue, silk emission and cocoon construction were not subjected to direct functional tests.

Subject of Research: Comparative larval mouthpart morphology and observed life-history traits in six Notodontidae moth species

Article Title: Comparative morphology of the larval mouthparts among six species of Notodontidae ( Insecta , Lepidoptera ), with discussions on their feeding habits and pupation sites

Article References: Liu, J.-X., & Jiang, L. (2023). Comparative morphology of the larval mouthparts among six species of Notodontidae (Insecta, Lepidoptera), with discussions on their feeding habits and pupation sites. Deutsche Entomologische Zeitschrift, 70(2), 357-368. https://doi.org/10.3897/dez.70.107431

Image Credits: AI Generated

DOI: 10.3897/dez.70.107431

Keywords: Notodontidae, caterpillar mouthparts, scanning electron microscopy, Nerice davidi, larval mandibles, maxillary sacs, spinneret morphology, leaf feeding, cocoon construction, pupation sites, Comparative, morphology

The aquafaba was prepared from chickpeas soaked for 24 hours and then pressure-cooked for 120 minutes. The cooking liquid was separated from the chickpeas, and its pH was measured at 6.15 ± 0.01 before being adjusted to approximately 5 with lemon juice. Its protein concentration was 1.12% on a wet basis and 17.42% on a dry basis, compared with 9.24% and 73.002% for egg white.

Aquafaba also contained less total material: its total solid content was 6.42%, compared with 12.69% for egg white. These compositional differences were consistent with the aquafaba’s lower ability to expand and stabilize foam in the study’s standardized whipping test. That test produced a marked difference between the two foaming ingredients.

After whisking, egg white reached 781.66% foaming capacity, meaning a much larger volume relative to the initial sample, while aquafaba reached 326.66%. Foam stability after 30 minutes was 97.22% for egg white and 84.03% for aquafaba. Aquafaba is not a single-component foaming agent: the study describes it as a mixture containing soluble proteins, saponins, carbohydrates, polysaccharides and fibrous components.

Proteins and saponins can contribute at interfaces, while soluble carbohydrates and polysaccharides influence the continuous phase. The measured gap nevertheless showed that the chickpea cooking liquid could foam, but did not match the expansion or persistence of egg white under the tested conditions. The researchers selected meringue as a relatively simple model of a foam and pancakes as a more complex fluid system containing starch granules, proteins and lipids.

For pancakes, the control contained 100 g of wheat flour, 40 g of egg white, 20 g of sugar, 2 g of salt, 4.5 g of baking powder and 108.5 g of water. The 50% formulation replaced 20 g of egg white with 20 g of aquafaba, while the 100% formulation replaced all 40 g of egg white with 40 g of aquafaba. For meringue, the formulations contained 250 g of powdered sugar and either 250 g of egg white, 125 g each of egg white and aquafaba, or 250 g of aquafaba.

All formulations were produced in three independent batches, with triplicate analyses and three technical replicates per production replicate. Replacing egg white lowered the density of both product types, a measured indication that the mixtures incorporated more air. Pancake batter density declined from 1.123 ± 0.003 g/mL in the egg-white control to 1.077 ± 0.03 g/mL at 50% substitution and 1.049 ± 0.03 g/mL at full substitution.

Meringue foam density fell from 0.156 ± 0.001 g/mL in the control to 0.138 ± 0.002 g/mL with 50% aquafaba and 0.123 ± 0.001 g/mL with complete replacement. These differences were significant at p < 0.05. Aquafaba therefore generated aerated systems, but the decrease in density did not translate into a stronger final structure.

Rheological measurements were conducted at 25°C and 1 Hz, equivalent to 6.28 radians per second, with strain amplitudes from 0.01% to 200%. In the linear viscoelastic region, the elastic modulus, G′, exceeded the viscous modulus, G″ for all pancake and meringue samples, indicating predominantly elastic, solid-like behavior. The egg-white controls had the highest modulus values.

Aquafaba reduced the elastic response, particularly in meringue, whose G′ values ranged from 0 to 1,600 Pa, compared with a G″ range of 0 to 400 Pa. Pancake G′ and G″ values ranged from 0 to 200 Pa and 0 to 100 Pa, respectively. Aquafaba also shifted the G′–G″ crossover in meringue to lower strain, showing that the substituted foams entered nonlinear behavior earlier.

The nonlinear response also differed by product. Meringues exhibited Type III weak strain overshoot: as strain increased, G′ declined and G″ rose before G″ decreased at the highest strains, a pattern associated with irreversible deformation and flow. At 200% strain, the pancake systems returned to strain softening after earlier strain stiffening, while the meringues shifted from shear thickening to shear thinning.

Chebyshev harmonic analysis gave the same broad distinction: pancakes showed positive third-to-first elastic coefficients and negative viscous coefficients in the nonlinear region, whereas meringues initially showed positive ratios for both before the viscous response became negative at 200% strain. Large-amplitude Lissajous–Bowditch curves separated the elastic and viscous parts of each stress cycle and showed that aquafaba reduced both stored and dissipated energy. The effect was especially pronounced in meringue made with 100% aquafaba.

Wider elastic stress loops in aquafaba-containing pancake samples indicated greater irreversible structural breakdown during flow, while narrower viscous loops and a more fluid-like response in fully substituted meringue indicated altered energy dissipation. The large-strain-to-minimum-strain elastic modulus and viscosity ratios also described the shift from linear to nonlinear behavior. Together, these observations indicated lower mechanical resistance in aquafaba-containing systems, even though the overall types of nonlinear response remained similar across the formulations.

Texture analysis confirmed that the baked products became softer as the replacement level increased. Control pancakes had a hardness of 47.49 ± 0.51 N, compared with 43.42 ± 0.52 N for the 50% formulation and 38.26 ± 2.03 N for the 100% formulation. Springiness, gumminess, chewiness and elasticity also generally decreased with more aquafaba.

For meringue, hardness fell from 69.37 ± 2.28 N in the control to 51.34 ± 1.93 N at 50% replacement and 43.28 ± 1.18 N at full replacement. Meringue fracturability declined from 60.09 ± 1.86 N to 47.67 ± 1.46 N and 42.68 ± 1.59 N, respectively. The texture measurements were consistent with the lower density, modulus and energy responses observed in the rheological analysis.

Scanning electron microscopy and cross-sectional images showed structural changes associated with the lower mechanical resistance. Pancakes containing higher proportions of aquafaba displayed fewer visible pores, while aquafaba-based meringues developed more layered and fragile structures. The images support the interpretation that the mixtures initially incorporated air but were less effective at retaining that aerated architecture during baking.

Color also changed with substitution. In pancakes, increasing aquafaba raised crumb brightness but lowered crust brightness; the highest redness values for both crumb and crust occurred in the 50% formulation. The authors associated the crust differences with the sugars and polysaccharides in aquafaba and their possible influence on Maillard browning and caramelization.

Overall, the study shows that aquafaba can perform useful foaming and structural functions in pancakes and meringues, but it does not reproduce the mechanical resistance of egg white. Its use produced lower-density, softer products with less capacity to withstand large deformation, and microscopy indicated less effective retention of incorporated air during baking. The authors identified several limitations and directions for further work: composition can vary with chickpea cultivar, genotype and preparation conditions, so future studies should test how protein, saponin, starch and soluble-carbohydrate contents affect air incorporation, deformation resistance and structural retention.

The same large-amplitude rheological approach could also be applied to other plant-based, high-shear foods. Sensory assessment, consumer acceptance and shelf-life studies would be needed before the practical performance of the most promising formulations could be fully evaluated.

Subject of Research: Laboratory assessment of aquafaba as an egg-white substitute in pancake batter and meringue foam

Article Title: Investigation of the Effects of Aquafaba Used Egg Replacers on Pancake Batter and Meringue Foam Rheology and Products Properties

Article References: Özyiğit, E., Erkoç, S., Özcan, İ., Kumcuoglu, S., & Tavman, Ş. (2026). Investigation of the Effects of Aquafaba Used Egg Replacers on Pancake Batter and Meringue Foam Rheology and Products Properties. Food Science & Nutrition, 14(10), Article e72392. https://doi.org/10.1002/fsn3.72392

Image Credits: AI Generated

DOI: 10.1002/fsn3.72392

Keywords: aquafaba, egg replacement, pancake batter, meringue foam, food rheology, large-amplitude shear, food texture, chickpea cooking water, plant-based foods, scanning electron microscopy, Investigation, Effects