Wiley-Online-Library: Acta Zoologica: Table of Contents

Issue Information

Mon, 01 Jun 2026 04:32:07 -0700

Acta Zoologica, Volume 107, Issue 3, July 2026.

Structural Characterisation of the Silk Gland of the Endemic Silkworm, Antheraea assamensis Helfer

Anurupa Goswami, Dipali Devi — Mon, 01 Jun 2026 04:32:07 -0700

ABSTRACT

Silkworms spin the highly prized and versatile silk among all the silk-secreting insects. The silk gland of these silkworms is the most efficient protein synthesizing system yielding a good variety of silk cocoons. Anthereaea assamensis Helfer is an endemic and unique non-mulberry silkworm species belonging to the Brahmaputra valley of Assam and adjoining hilly areas. Herein this study, the silk gland was dissected out and divided into three distinctive parts: posterior (PSG), middle (MSG) and anterior (ASG) silk gland. Various microscopic techniques were adopted to understand the histological and ultrastructural components of the silk gland along with the flow of liquid silk in it. The fluorescence microscopic examination of the three silk gland parts showed nuclear ramification with an increasing pattern during the 4th and 5th instars. Light microscopic study of the PSG and MSG showed a tight secretory nuclear structure with a distinct epithelium and an unorganised, thin epithelial structure with large secretory vesicles, respectively. The ultrastructural study of the 5th instar matured larval PSG displayed a uniform and thick layer of basement membrane. MSG showed similar characteristics with the occurrence of sparsely distributed infoldings. This first comprehensive organisational study of the silk gland parts of A. assamensis Helfer revealed the structural features responsible for silk synthesis, storage and its secretion.

Comparative Anatomy and Immunohistochemical Study of Eyelids in Two Different Avian Species: Expression of CD20+, CD138+ and CD1a+ Cells in the Mucosa of the Eyelid

Mon, 01 Jun 2026 04:32:07 -0700

ABSTRACT

The objective of this study was to discuss the influence of the environment on the macro–microstructure features of the eyelids of two birds: hooded crow, Corvus cornix, and Muscovy duck, Cairina moschata, which also show lymphoid follicles, lymphocytes and some immune cells in the eyelid mucosa and their effect on healthy eyes. In both birds, numerous lymphocytes were distributed within connective tissue in the tarsal and orbital regions of the lower eyelid, and lymphoid follicles were located mostly beneath the conjunctival tissue near the tarsal plate to form a part of diffuse conjunctiva-associated lymphoid tissue. There were no lymphoid follicles in the upper eyelid or nictitating membrane of the crow. However, they appeared in the nictitating membrane of the duck. In the crow, CD1a-positive cells were marked in the skin and CD20-positive population was detectable as a small patch in the intrafollicular, while in the duck, few CD1a-positive cells were scattered in the stroma and there was a weak reaction around the feather follicle, while a densely positive CD20 was found in the paracortex and medullary regions of the follicle and in the stroma beneath the skin, also around blood vessels and HEV in both birds. CD138+ cells are scattered in the stroma and their population increases around blood vessels and HEV. In the third eyelids, CD20+, CD138+ and CD1a+ show an increase in concentration around blood vessels, with plasma cells having the highest density, while the lowest population of CD20+ is dispersed as singular cells between the two membrane surfaces. Thereby, these changes in the morphology of the upper, lower and third eyelids were strongly related to the lifestyle of the birds.

Comparative Egg Morphology of Four Species of Erebidae (Lepidoptera) From China

Mon, 01 Jun 2026 04:32:07 -0700

ABSTRACT

The chorionic sculpture of the eggs of Euproctis pulverea (Leech, 1888), Lymantria dissoluta Swinhoe, 1903, Arctornis nivea Chao, 1987, and Spilarctia subcarnea (Walker, 1855), was examined and described in detail by utilising light and scanning electron microscopy. Euproctis pulverea could be distinguished from L. dissoluta by the egg densely covered with hairs and the sculpture only displayed in the micropylar area. Arctornis nivea is unique in that the apex of the egg is dish-shaped and the bottom is smoothed, and the micropyles opening five star-shaped. Spilarctia subcarnea is characterised by four or five star-shaped micropyles of the egg chorion, concaved primary cells with intertwined fibres, and numerous aeropyles expressed on the ridges. We briefly discussed the significance of egg chorionic morphology in taxonomic and systematic studies in Erebidae.

Life History of Tug Valley Crayfish Cambarus hatfieldi Loughman, Fagundo, Lau, Welsh & Thoma 2013 (Decapoda: Astacoidea: Cambaridae) in Southwestern West Virginia, USA

Christopher G. Vopal, Zachary J. Loughman — Mon, 01 Jun 2026 04:32:07 -0700

ABSTRACT

Life history data for Cambarus hatfieldi Loughman, Fagundo, Lau, Welsh, & Thoma, 2013 were collected from March through December 2018 from Dry Fork at War, West Virginia, USA. Cambarus hatfieldi is syntopic with Cambarus callainus Thoma, Loughman & Fetzner, 2014 through part of its range, with the latter having been listed as threatened by United States Fish & Wildlife Service under the Endangered Species Act in 2016. No ovigerous females with pleopodal eggs were collected; however, mean ovarian egg diameter peaked in July, which correlated with ovigerous females from the West Liberty Crayfish Collection which were collected in August 2009 at nearby Barrenshe Creek. Mature male total carapace length (TCL) ranged from 29.3 to 52.6 mm and mature female TCL ranged from 29.7 to 48.1 mm. Morphometric analysis provided evidence of form change in female C. hatfieldi. Relative abundance of form I males to form II males was greater in March, April, May, October and December; declining below form II going into the summer. Six size classes, or cohorts, were determined by analysis of peaks on monthly histograms of TCL. Cambarus hatfieldi young of the year (YOY) appear to enter the population around October, with delayed growth until Spring.

Histological and Electron Microscopy Observations on the Alimentary Canal and Malpighian Tubules of the Strawberry Pest Coraebus elatus (Fabricius, 1787) (Coleoptera, Buprestidae)

Nurcan Özyurt Koçakoğlu, Üzeyir Çağlar, Hicret Arslan, Selami Candan — Mon, 01 Jun 2026 04:32:07 -0700

ABSTRACT

Coraebus elatus (Fabricius, 1787) (Coleoptera, Buprestidae) is known as a strawberry pest, making it an essential target for pest control strategies. Despite its impact, no studies have examined the anatomical and histological structures of the alimentary canal and Malpighian tubules of C. elatus. Therefore, this study aimed to describe these structures in detail, which could provide insights into potential control methods. Ten individuals were collected and histologically processed, with observations made using stereo, light and electron microscopies. The alimentary canal is divided into three sections: the foregut, midgut and hindgut. The foregut comprises the pharynx, oesophagus, crop and proventriculus. A gastric caeca pair lies at the proximal anterior end of the midgut. The midgut is the longest portion. The Malpighian tubules, whose proximal ends open into the midgut and hindgut, have distal ends that connect to the colon wall. The hindgut is further subdivided into the ileum, colon and rectum. The rectum, the final segment of the alimentary canal, has a thick muscular wall and a more pronounced intima layer than the other hindgut regions. Cross sectional SEM images show six rectal pads where the final absorption of nutrients occurs. These findings may lead to new strategies for controlling this agricultural pest. Understanding these structures is crucial for further research.

First Zoeal Stage of the Snapping Shrimp Alpheus Fabricius, 1798 (Caridea: Alpheidae): New Description of Alpheus bouvieri A. Milne‐Edwards, 1878 and Literature Review

Karmine Pasinatto, Alexandre O. Almeida, Mariana Terossi — Mon, 01 Jun 2026 04:32:07 -0700

ABSTRACT

Based on adult morphological characters, the more than 300 species of Alpheus were divided into seven informal species groups, but some groups are not supported by molecular data. The aim here was to describe the zoea I of Alpheus bouvieri, and to do a review of the larval descriptions available in the literature, analysing whether the morphological groups proposed for adults are supported by larval data. The new larvae were obtained from females sampled in Pernambuco and Rio Grande do Norte, Brazil. Alpheus bouvieri zoea I shares a combination of characters with most larvae in the genus, but with some diagnostic characteristics: endopod of the maxillule and maxilla with 3 and 4 setae, respectively, the base of the first maxilliped with 9 setae, endopod of the second and third maxilliped with 5 and 6 segments, respectively. In our review, 23 species were analysed from five groups: edwardsi (thirteen), sulcatus (four), brevirostris (three), macrocheles (two), and obesomanus (one) group; the zoea I of species from diadema and crinitus groups are unknown. Based on this review, many issues regarding mistakes in the zoea I description of Alpheus are pointed out, and the hypothesis that the morphological groups proposed for adults are supported by larval data has been rejected.

Morphology of the Female Reproductive System of the Water Scorpion Nepa cinerea Linnaeus, 1758 (Nepomorpha: Heteroptera)

Nurcan Özyurt Koçakoğlu, Hakan Özdamar, Hicret Arslan, Selami Candan — Mon, 01 Jun 2026 04:32:07 -0700

ABSTRACT

Nepa cinerea is an aquatic predatory insect that plays a key role in the biological control of mosquito populations. This study investigates the morphological structure of the adult female reproductive system using stereomicroscopy, light microscopy and scanning electron microscopy. The reproductive system comprises two ovaries, lateral oviducts, a common oviduct, a spermatheca, and a genital chamber. Each ovary contains five telotrophic meroistic ovarioles, which are divided into four regions: a terminal filament, a germarium with trophocytes and early-stage oocytes, a vitellarium containing previtellogenic, vitellogenic, and choriogenic oocytes, and a long pedicel. Choriogenic oocytes display distinct endochorion and exochorion layers. Each pedicel contains 2–3 pale yellow, oval eggs with brown respiratory horns. Pedicels connect to the common oviduct via the lateral oviducts. The spermatheca, composed of a distal reservoir and a proximal duct, also opens into the common oviduct. The reservoir is cuticle-lined and surrounded by longitudinal muscles and glandular cells. Features such as ovariole number and the presence of respiratory horns differ among aquatic heteropterans. These findings offer valuable insights into the comparative morphology of female reproductive systems in aquatic Heteroptera.

An Integrative Insight Into the Taxonomic Validity and Morphological Variation in the Malay Puntius Complex (Cypriniformes: Cyprinidae)

Mon, 01 Jun 2026 04:32:07 -0700

ABSTRACT

Puntius sensu lato has many species but is seen as an artificial grouping for unrelated cyprinids. The correct taxonomic identification and taxonomic status of the Puntius complex have been challenged due to their minor morphological differences. This study investigates the morphological variation and taxonomic validity of 10 species within the Malay Puntius complex using an integrative approach. In the traditional analysis, a one-way analysis of variance (ANOVA) revealed that 28 out of 30 traits (20 morphometric and 10 meristic characters) were significant. Discriminant function analysis (DFA) indicated significant morphological variation among morphotypes, particularly in meristic traits. This analysis correctly classified 82.8% of the originally grouped and 74.5% of the cross-validated groups based on meristic characters. Truss analysis indicated that 14 out of 22 characters were significant (p < 0.05). The geometric morphometric analysis was largely consistent with the morphometric and truss analyses, confirming the validity of the distinct species. Molecular phylogenetic analyses of mitochondrial COI gene sequences confirmed the validity of all species. However, consistent with morphological data, they also supported the non-monophyly of the genus Barbonymus.

Ultrastructural Morphology of the Red Palm Weevil (Rhynchophorus ferrugineus) and Its Associated Phoretic Invertebrates: A Scanning Electron Microscopy Study

Nasra M. H. Zohry, Yahya Al Naggar, Ali Ashry — Mon, 01 Jun 2026 04:32:07 -0700

ABSTRACT

The red palm weevil (Rhynchophorus ferrugineus Olivier) is a highly destructive pest that severely threatens palm trees due to the feeding activity of its larvae and adults. The concealed lifestyle of R. ferrugineus, with larvae developing inside palm trunks and adults tunnelling through tissues, has led to specialised morphological and physiological adaptations that facilitate their survival and proliferation. Understanding these adaptations is critical for developing effective management strategies. This study investigates the external morphology of both larval and adult stages, along with their sensory structures, using scanning electron microscopy (SEM). The analysis revealed distinct sexual dimorphism, particularly in the structure of the rostrum and sensory organs. Additionally, the mouthpart morphology of larvae was examined, highlighting adaptations suited for wood boring. Various sensillae were identified across both sexes, including infrared sensilla, spicules, and spiracles elevated above the thoracic and abdominal surfaces, surrounded by protective spines. Five distinct morphotypes of sensillae were characterised: multiporous peg sensillae, sensilla coeloconica (Types I, II, III), bifid trichoid sensilla, and sensilla trichoidea (Types I, II), with no significant differences observed between males and females. Furthermore, SEM analysis documented the presence of phoretic mites, specifically deutonymphs of Uroobovella sp., on both male and female weevils and pupae. Notably, fungal spores associated with these mites were detected, suggesting a potential role in pathogen transmission that may contribute to palm tree deterioration. These findings provide valuable insights into the morphological adaptations of R. ferrugineus and the ecological interactions that may influence its impact as an invasive pest.

Age‐Specific Survival and Fecundity Life Table of Callosobruchus chinensis (L.) on Selected Pulses in the North‐Western Himalayan Region of India

Vasu Mehta, Ravinder Singh Chandel, Vishrava Katoch, Khushwinder Singh — Sun, 31 May 2026 21:31:13 -0700

ABSTRACT

Pulses play a crucial role in Indian agriculture, contributing significantly to the national economy through substantial export revenue. India is the largest global producer of pulses. These crops are rich in protein (20%–25% by weight), which is approximately twice that of wheat and three times that of rice. However, pulses are susceptible to various insect pests during storage, with the pulse beetle, Callosobruchus chinensis, being a major pest responsible for considerable damage across different pulse varieties. According to life table analysis, the highest Gross Reproductive Rate (GRR) and also Net Reproductive Rate (NRR) were observed in green gram, with values of 56.98 and 34.49, respectively. In contrast, kidney bean exhibited the lowest values for both GRR (26.33) and NRR (8.00). Both the true generation time and doubling time were shortest for green gram (20.70 and 4.05, respectively), while black gram had the longest true generation time (30.97), and kidney bean had the longest doubling time (9.26). Based on intrinsic rate of increase, doubling time, and hypothetical F₂ females, host suitability varied among pulses, with green gram being the most suitable and kidney bean the least. These findings provide insights into population dynamics and host suitability of C. chinensis, which can aid in developing effective storage pest management strategies.

Freezing the Eversible Glands: An Ultramorphological Study of Larval Nematus Japonicus (Hymenoptera: Tenthredinidae)

Dong Liu, Chun‐Mao Lü, Wei Niu, Ping Guan, Lu Jiang — Mon, 25 May 2026 21:40:11 -0700

ABSTRACT

Eversible exocrine glands play a central role in chemical defence and signalling in insect larvae, yet their fine morphology remains poorly understood because these structures are normally retracted and difficult to observe. In sawflies (Hymenoptera: Tenthredinidae), particularly within Nematinae, chemical composition and defensive function of ventral eversible glands have been well documented, whereas ultrastructural information on the exposed gland surface has been lacking. Here, an approach was developed to stabilize the eversible gland of Nematus japonicus (Takeuchi 1921) larvae in its everted state, enabling detailed examination using scanning electron microscopy. The everted gland surface is characterized by dense cuticular folding without discrete pores or microtrichia, suggesting a thin, weakly sclerotized integument adapted for diffusion-based release of volatile compounds. In addition, a previously unreported sensory field is documented on the larval abdomen, including rows of papilla-like sensilla and dense arrays of sensilla chaetica surrounding the anal slit. These sensory structures are interpreted as components of a coordinated behavioural system involved in faecal expulsion and defensive posture. Together, these findings provide the first ultrastructural characterization of a nematine eversible gland and establish a morphological framework linking gland structure, sensory organization, and defensive behaviour in sawfly larvae.

Tongue and Glottis Morphology of Cathartes aura and the Secret of Its Functional Adaptation

Thu, 21 May 2026 20:55:35 -0700

ABSTRACT

Cathartes aura, commonly known as the Turkey vulture, is a scavenger bird belonging to the family Cathartidae that is widely distributed throughout the Americas and classified as a New World vulture. Its diet primarily consists of small-sized carcasses, predominantly of wild animals. These dietary patterns, combined with the vulture's behaviour, suggest that food selection may be influenced by competition with more dominant species during disputes over resources. The potential link between gustatory experiences and tongue morphology remains largely unknown. Through macroscopic analysis, light microscopy and scanning electron microscopy, we identified that the tongue of Cathartes aura is short, non-protrusible, and supported by the hyobranchial apparatus, which is composed of long, thin and articulated bones. The tongue has an elongated and concave shape and possesses mechanical papillae arranged along its lateral margins. The dorsal regions of the body, root, glottis and laryngeal mound revealed a significant presence of tubuloalveolar salivary glands, connective tissue, muscle fibres oriented in multiple directions, and bone structures, in addition to vascular and nervous components. No taste buds were visualised. The anatomical adaptations of the tongue in Cathartes aura represent an important functional mechanism, which optimises its feeding strategy and reduces the exposure time spent on carcasses.

Longevity and Growth of the Crabs Callinectes sapidus and Callinectes rathbunae (Decapoda: Portunidae) in Paraíso Tabasco Mexico

Tue, 28 Apr 2026 03:45:44 -0700

ABSTRACT

Individual growth models are important in fisheries of natural populations and can be incorporated in production models to estimate their maximum sustainable yield. Blue crab species, Callinectes sapidus and Callinectes rathbunae were obtained in the Mecoacán lagoon, Paraíso, Tabasco Mexico by “nasa” and “yahual” nets. Biometric values such as carapace length and width were measured, as well as the weight of the eviscerated organisms. Growth expressions (von Bertalanffy's parameters K and L _∞) for each species and sex were obtained by using ICLARM ‘S FiSAT program, with which yearly weight for each sex of the two species were calculated, as well as phi and longevity values. It was observed that C. sapidus males grow faster than females, both in size and weight, while C. rathbunae females grow slightly faster than males, with the latter gaining more weight than females. C. sapidus presents an hipoallometric relative growth while C. rathbunae presents a relative growth tending to isometry. The phi indices show that there is a difference in the growth between species and sexes.

Developmental Stability Across Seasons but Not Months: Wing Asymmetry Responses of an Orchid Bee to Short‐Term Climate Variability

Fri, 10 Apr 2026 03:49:17 -0700

ABSTRACT

Fluctuating asymmetry (FA) and wing shape variation have been widely proposed as sensitive indicators of developmental instability and environmental stress in insects, yet their temporal dynamics remain poorly explored in tropical systems. In this study, we examined fine-scale temporal and environmental variation in wing FA and shape of the orchid bee Euglossa imperialis Cockerell, 1922 within a tropical dry forest of central Panama. Using geometric morphometrics, we quantified bilateral wing asymmetry and shape variation across monthly sampling periods spanning dry and rainy seasons, integrating high-resolution climatic data. Overall FA values were low and showed no significant differences between seasons, indicating high developmental stability across broad seasonal regimes. Similarly, wing shape exhibited extensive overlap between dry and rainy seasons, with no discrete seasonal differentiation. In contrast, both FA and wing shape varied significantly among months, revealing a gradual and continuous temporal signal. Minimum temperature and relative humidity emerged as the main environmental variables associated with FA, whereas precipitation showed no detectable effect. These results indicate that developmental instability and wing morphology in E. imperialis are primarily shaped by short-term climatic variability rather than by categorical seasonal contrasts. Our findings highlight the importance of fine temporal resolution when evaluating morphological responses to environmental conditions and suggest that FA and wing shape function as scale-dependent indicators of environmental variation. Integrating geometric morphometrics with high-resolution climate data provides a powerful framework for refining the use of orchid bees as bioindicators in tropical ecosystems.

Anatomy and Histology of the Midgut of Atopozelus opsimus (Heteroptera: Reduviidae)

Wed, 08 Apr 2026 04:30:37 -0700

ABSTRACT

Atopozelus opsimus Elkins, 1954 (Heteroptera: Reduviidae) preys on forest and agricultural pests but also feeds on extrafloral nectar; however, its alimentary canal is poorly understood. The aim was to describe the anatomy and histology of the A. opsimus midgut. The alimentary canal of female and male A. opsimus was dissected, examined, processed, and analysed using light microscopy, revealing three midgut ventricles (V1, V2 and V3) in the midgut with similar morphology in both male and female. The digestive epithelium of V1 and V2 has a well-developed apical brush border, a nucleus rich in decondensed chromatin and evident nucleolus, cytoplasm with basophilic granules and the lumen with multiple layers of perimicrovillar membrane. In the ventricle V3, the columnar digestive cells have an apical short and irregular brush border closely associated with some profiles of microvillar membrane, the nucleus with decondensed chromatin and the cytoplasm rich in basophilic granules and clear vacuoles. The midgut features suggest potential different functions, with V1 and V2 possibly having functions of secretion and absorption, whereas V3 may play some role in absorption and storage.

Ultrastructural Characteristics of Keratinization and Secretion in the Epidermis of Some Antarctic Fishes in Relation to Their Cold Adaptation

Lorenzo Alibardi, Chiara Maria Motta — Tue, 07 Apr 2026 06:56:10 -0700

ABSTRACT

Ultrastructural characteristics on keratinization and secretion in the epidermis of some Antarctic fishes in relation to their cold adaptation. Acta Zoologica (Stockholm). Antarctic fishes evolved specific adaptations in the skin, the first organ contacting freezing water. We examined the epidermis of two red-blooded species (Trematomus bernacchii and T. newnesi; family Nototheniidae) and a white-blooded species (Chionodraco hamatus; family Channichthyidae) to provide morphological evidence of cold resistance. The thick epidermis comprises basal, intermediate and apical regions. Cubic-columnar basal keratinocytes are joined to the thick lamina densa of the basement membrane along their plasma membrane. In the intermediate and apical regions, keratinocytes flatten and store keratins, forming an electron-dense cortical region. Numerous desmosomes tightly connect keratinocytes, forming a mechanical barrier that may prevent crystal ice entry. During keratinocyte differentiation, the central cytoplasm remains electron-pale and is enriched in tubular/vesicular mitochondria, SER cisternae and smooth vesicles. Lipids might contribute to thermal barrier formation across the epidermis. Moving toward the skin surface, flattening keratinocytes form microridges, while their organelles degenerate. Lipid degradation may release anti-freeze glycerol that adds to glycoprotein/glycolipid secretions. Likely, more mechanisms are working together to protect the skin from freezing. The thick basement membrane and numerous desmosomes help prevent ice entry, while lipids provide thermal insulation. These two adaptations would support the protection exerted by the presence of antifreeze glycoproteins and high tissue osmolarity.

Macropinocytosis Generates New Microridge Patterns in Fish Epidermis Cells

Joseph A. DePasquale — Sun, 08 Mar 2026 21:00:13 -0700

ABSTRACT

Actin-based microridges are fingerprint-like patterned protrusions located on the apical surface of fish epidermal cells. Originally believed to be static structures microridges are now known to be dynamic entities that form from individual substructures, actin puncta, or from annealing of smaller established ridges into larger ones. Conversely, larger ridges can fragment into smaller segments or even be reduced to puncta. Cellular processes such as cytokinesis can physically alter microridge patterns, reducing these structures to individual puncta which then reassemble into microridges upon completion of cell division. Apical Rings are circular macropinocytotic structures constitutively active at the surface of fish epidermis, causing local disruption of the microridge pattern. The present study demonstrates that after macropinocytosis, different patterns are generated upon assembly of new microridges. Microridge patterns remain relatively stable in the absence of macropinocytotic activity. The results suggest that constitutive macropinocytotic activity has the potential to create entirely new microridge patterns.

First Insights on Photoreceptor Organ Ultrastructure in Marine Chaetonotida (Gastrotricha): Species of Xenotrichula and Draculiciteria (Xenotrichulidae)

Thiago Quintão Araújo, Rick Hochberg — Fri, 06 Mar 2026 20:27:00 -0800

ABSTRACT

Marine gastrotrichs inhabit sediments with limited available light, yet evidence suggests that photoreceptor organs are present throughout the phylum Gastrotricha. Here, we confirm this proposition with ultrastructural descriptions of photoreceptive organs in two species of Xenotrichulidae (Order Chaetonotida) that lack pigmented ocelli. Xenotrichula intermedia possesses a pair of dorsal, extracerebral cells that fit the description of photoreceptor cells in other gastrotrichs. Both sensory cells are bipolar with an apical dendritic end of microvilli-like projections that protrude into a thin, cup-like extension of a sheath cell. Neither the sheath cell nor surrounding cells possess shielding pigments. Both sensory cell bodies contain highly granular cytoplasm with a nucleus, inflated rough endoplasmic reticulum, membrane-bound vesicles, and several microtubule-like structures. The photosensory cells extend into the cerebral ganglion, apparently bypassing a cellular capsule around the brain. The presumed photoreceptive organs of D. tesselata were incompletely documented, but possess extracerebral, dendritic projections encapsulated by non-pigmented sheath cells in identical positions to those of X. intermedia. The present data support the proposition that chaetonotid gastrotrichs possess photoreceptive organs with a similar morphology to those of Order Macrodasyida, thus confirming that all gastrotrichs, even those without pigmented eyespots, may possess photoreceptive organs.

Immunolocalization of Shh and Chordin in the Regenerating Tail of the Lizard Podarcis muralis

Lorenzo Alibardi — Fri, 06 Mar 2026 06:17:01 -0800

ABSTRACT

The transcriptome of the regenerating tail in the wall lizard, Podarcis muralis, has indicated the up-regulation of genes for chordin and shh, but the localization of these proteins in the regenerating tail is poorly known. The present immunohistochemical study has analysed early regenerating lizard tails. Chordin is almost exclusively present in the regenerating spinal cord, made of an ependymal epithelium surrounded by regenerating axons, and in sparse peripheral regenerating nerves. It is unknown whether chordin may stimulate differentiation in surrounding tissues. Chordin immunolocalization resembles that of shh in the regenerating spinal cord. Electron microscopy immunodetection of shh shows its prevalent localization in the cytoplasm of regenerating ependymal cells, from which it may be secreted into the mesenchyme of the regenerative blastema. Shh is also detected in the wound epidermis and regenerating scales but is scarce or completely absent in nerves, muscles, connective tissues and cartilage. In regenerating scales, shh appears localised in the differentiating epidermal layers, in particular in the new beta-layer, suggesting that shh is also implicated in the stimulation of beta-cell differentiation. The elective distribution of the two proteins in ependyma and epidermis suggests that they have a fundamental role in the stimulation of tail regeneration in lizards.

Larval Descriptions of Two Potimirim (Holthuis, 1954) Species and Identification Key for the First Larval Stage of Amphidromous Shrimps From Brazil (Decapoda: Caridea)

Tue, 24 Feb 2026 20:22:51 -0800

ABSTRACT

Amphidromy, a migratory pattern characterised by the development of planktonic larvae in estuarine waters and coastal zones while adults live and reproduce in freshwater, is observed in the life cycle of some species of caridean shrimps. In Brazil, amphidromous shrimps are represented by the families Atyidae, with the genera Atya Leach, 1816, and Potimirim Holthuis, 1954, and Palaemonidae, with the genera Macrobrachium Spence Bate, 1868, and Palaemon Weber, 1795. Accurate identification and understanding of the planktonic larvae of these shrimps are essential for ecological studies, population dynamics, taxonomy and phylogenetics of these species, as well as the understanding of the life cycle adaptation. This study aimed to investigate the potential of the morphology of the first larval stage (zoea I) for identifying amphidromous shrimp species occurring in Brazil, through the development of a dichotomous identification key. We described the zoea I of the two species of the genus Potimirim and conducted a bibliographic review to select all the studies describing the larvae of amphidromous shrimps found in Brazil. Based on outer and inner morphological characters as well as setation patterns of the first larval stage, we constructed a dichotomous key covering 14 taxa, of which 10 were identified at the species level. Despite the overall morphological similarity observed among the zoeae I, the combined use of diagnostic characters allowed reliable discrimination for all analysed larval descriptions. The illustrated plates and identification key provide a practical and standardised tool for species identification, contributing to planktonic studies, taxonomic research and the understanding of early life stages of amphidromous shrimps in Brazil.

Life History, Natural History, and Ecology of Cambarus veteranus Faxon 1914 (Decapoda: Astacoidea: Cambaridae) in the Clear Fork Watershed of the Guyandotte River, West Virginia

Nicole M. Sadecky, Zachary J. Loughman — Mon, 02 Feb 2026 01:59:08 -0800

ABSTRACT

Cambarus veteranus Faxon 1914 (Guyandotte River Crayfish), is a federally endangered, narrow endemic. A 2 year life history study was initiated for C. veteranus in Clear Fork of the Guyandotte River, Wyoming County, West Virginia, USA. Monthly collections began June 2017 and continued through May 2019. Specimens, regardless of species, were collected, sexed, and moult stage determined. Monthly length frequency distributions identified five age-size classes for the population assessed. Form I males were collected all months sampled and reached their highest density in April. Mature females with signs of glair were captured nearly every month but reached their highest density in June. A single female bearing pleopodal eggs was captured in August and females with Stage 4 juveniles were subsequently observed in September and November. Females overwintering with juveniles were evidenced by females captured with Stage 4 juveniles in March for both years sampled. Two synchronous moulting events were identified for the population around seasonal thermal shifts with the highest frequency of moulting individuals observed in May and September. Our exploration of discontinuous growth utilised non-traditional growth models due to the small sample sizes per age-size class. The results corroborated the expected growth for Cambarus crayfish. Differences in timing for ontogenic allometric shifts in growth were observed between males and females and provided insight into when resources shift from general growth allocation to growth required for reproduction. This study employed unique life history methodologies, rarely applied to crayfish, to provide information essential for the successful conservation of this endangered species, while enabling comparisons with closely related species often assumed to share similar life history strategies.

The Embryonic Development of the Cotylean Polyclad Phrikoceros jannetae

Wed, 07 Jan 2026 02:06:01 -0800

ABSTRACT

Polyclads exhibit distinct developmental modes ranging from direct to indirect development, with several transitional stages also recognised. The existence of an indirect developmental mode in polyclads with a planktonic life history stage in the form of a free-swimming larva is unique among all free-living flatworms and makes polyclads a compelling subject for comparative studies. Early development is robust across different polyclad species, including direct and indirect developers, stemming from the polyclad flatworms' retention of a stereotyped spiral cleavage pattern, a trait shared with other phyla grouped as the Spiralia. Using a live-imaging approach, we describe the embryonic development of the cotylean polyclad Phrikoceros jannetae (Pseudocerotidae), documenting all major developmental stages from meiosis to the formation of a three-eyed, six-lobed larva. We characterise key events such as cytoplasmic perturbations during meiosis, early cleavages in macromeres, and the appearance of larval morphological features including eyes and lobes. By aligning individual developmental trajectories to the 4-cell stage, we provide a coherent timeline that facilitates comparisons across embryos. This work expands the developmental knowledge of P. jannetae and contributes to a broader understanding of embryogenesis within Pseudocerotidae. Additionally, our observations reinforce previous findings on symmetry breaking in polyclads, particularly the pivotal role of micromere 4d, a process often overlooked in studies relying solely on static images.

Review: Cell and Molecular Biology of Healing in Amputated Limbs of the Lizard Podarcis muralis Reveal a Gene Activation Program for Scarring

Lorenzo Alibardi — Mon, 22 Dec 2025 22:13:29 -0800

ABSTRACT

The present review summarises cell biology and transcriptome data describing cell and extracellular matrix reaction to the injury in the amputated lizard limb and its poor regeneration. Immuno-electron microscopy indicates massive penetration of immune cells among injured tissues during the first 1–3 weeks post-amputation. Injured connective tissues, muscles, bone, and cartilaginous tissues undergo a process of dedifferentiation. Numerous proliferating fibroblasts derive from the injured tissues, but muscles and cartilage are repaired without further growth of repaired myofibers. A dense connective tissue is later formed, leaving a scar-like outgrowth that becomes scaled. Aside from chondrocytes proliferation from the injured bone with alcian-blue positive matrix for acidic glycosaminoglycans, no alcianophilic matrix is formed in connectives of the scarring limb. The up-regulated genes coding for extracellular matrix proteins during this period reveal the production of specific collagens, enzymes, and matrix proteins whose function determines a scarring program of differentiation. No transcriptome data are available for lizard developing limbs, so no comparison with the scarring limb is possible. Limb tissues in lizards undergo a process of dedifferentiation for repairing but cannot regenerate large masses of new tissues into a functional new limb. These reptiles provide useful comparative information for studies on amniotes regeneration.

Allometry, Sexual Maturity and Intraspecific Morphological Variations in Aegla jacutinga Marçal and Teixeira, 2020 (Crustacea, Anomura)

Fri, 14 Nov 2025 03:54:41 -0800

ABSTRACT

Crustaceans of the genus Aegla represent a taxonomically challenging group, with numerous morphologically similar species. This study investigates the growth patterns, morphological maturity and sexual dimorphism in Aegla jacutinga, through allometric analyses of 661 specimens. The results revealed three ontogenetic stages in males (young, adult Morphotype I and Morphotype II) and two in females (young and adult), with significant differences in relative growth. Morphometric maturity was reached at similar sizes between sexes (males: 8.34 mm; females: 8.43 mm), but with marked sexual dimorphism: adult males showed marked positive allometry in the chelipeds, while females exhibited greater abdominal growth. The species demonstrated significant heterochely (p < 0.05) and laterality with predominance of the left chela in both sexes (73% of males; 71% of females). Analyses of intraspecific morphological variation identified modifications in diagnostic characters throughout development, with only 30%–40% of the characteristics remaining stable between demographic groups. These findings highlight the need to integrate ontogenetic series into taxonomic descriptions and reinforce the importance of combining morphological, molecular approaches and geographical distribution for species delimitation in this genus with cryptic species. The study provides unprecedented bases for the identification of life stages and dimorphism in A. jacutinga, in addition to evidencing limitations of traditional morphological characters.

Morphology of the First Zoeal Stage of the Shrimp Typton distinctus Chace, 1972: The Second for the Genus Typton O.G. Costa, 1844 After 100 Years

Matheus Sene, Rogerio Caetano Costa, Rafael Carvalho Santos — Sat, 08 Nov 2025 06:10:13 -0800

ABSTRACT

The marine shrimp of the genus Typton are widely distributed, known to be associated with sessile organisms such as sponges. Information about this genus is limited, highlighting the scarcity of important features in its biology, including larval forms. This study aims to describe the first larval stage of Typton distinctus, marking the third larval description for the genus and the second for the first zoea after 100 years. An ovigerous female was sampled manually by freediving in January 2019 at Cais do Porto, Itaguá Bay, Ubatuba, São Paulo. The parental female was kept in an aquarium until the larvae hatched. The morphology of the first larval stage was described and illustrated, then compared to the only first zoea of the genus available in the literature in this stage, T. spongicola, to identify diagnostic larval patterns in the genus. Both species shared similar morphological characteristics, typical of first zoea in caridean shrimp; however, an elevated number of distinct traits were identified too that could be a result of incomplete details in the description of T. spongicola. This study enhances the understanding of Typton larvae, assisting in their identification and providing information for future research on this genus through the morphological data provided.

Higher Levels of Limb Loss and Temperature Accelerate Limb Regeneration in Marbled Crayfish (Procambarus virginalis)

Kifayatullah Mengal, Golara Kor, Pavel Kozak, Hamid Niksirat — Thu, 30 Oct 2025 21:30:48 -0700

ABSTRACT

Regeneration allows decapod crustaceans to restore lost limbs and is considered a critical adaptation for survival in aquatic ecosystems. However, the effects of limb loss severity on regeneration rate, moulting and survival remain insufficiently explored. Temperature, a key abiotic factor, also influences these processes. In this study, we examined the combined effects of limb loss severity (categorised as Intact, Medium and High) and temperature (14°C and 24°C) on the regeneration and mortality rates of marbled crayfish (Procambarus virginalis), a model organism for decapod crustacean studies. Our results show that greater limb loss accelerated regeneration, likely due to the functional necessity of replacing limbs required for locomotion, foraging, mating and defence. Additionally, regeneration occurred at a faster rate at 24°C, indicating a temperature-dependent response. The interaction between temperature and limb loss severity had a synergistic effect on moulting and regeneration. However, the combined effects of high limb loss and temperature increased mortality, suggesting that the energetic demands of regeneration under these conditions exceed physiological tolerance. These findings provide critical insights into the ecological and physiological mechanisms underlying crustacean regeneration, with implications for broader invertebrate biology under changing environmental conditions and aquaculture.

Geometric Morphometrics Reveal Body Shape Variation in Freshwater Shrimps of the Genus Macrobrachium Lacking a Mandibular Palp (Formerly Pseudopalaemon Sollaud, 1911) (Decapoda: Palaemonidae)

Wed, 29 Oct 2025 04:08:35 -0700

ABSTRACT

Shape variation in the cephalothorax of Macrobrachium species without mandibular palp using geometric morphometrics was used as a tool to support species differentiation and propose new diagnostic characters for taxonomic identification. A total of 170 specimens from six species of the genus Macrobrachium without palp were analysed: Macrobrachium amazonensis (Ramos-Porto, 1979); M. bouvieri (Sollaud, 1911); M. chryseus (Kensley & Walker, 1982); M. gouldingi (Kensley & Walker, 1982); M. iquitoensis (García-Dávila & Magalhães, 2004); and M. nigramnis (Kensley & Walker, 1982). Nineteen landmarks and semi-landmarks were digitised for 2D landmark-based morphometric geometric procedures. Principal component analysis and canonical variation analysis revealed significant shape distinction between species within the group of Macrobrachium species without palp. Macrobrachium amazonensis exhibits the greatest shape variation, while M. bouvieri is the most morphometrically distinct. Relevant morphometric variation among species of Macrobrachium species without palp was detected with high accuracy (> 91%; p < 0.05), suggesting that the shape of the lateral cephalothorax, rostral curvature and position of the antennal teeth are the main morphological features for species discrimination. Species shape distinction in the cephalothorax also revealed relevant discrimination between the Río de la Plata Basin and the Amazonian species. The shape of cephalothorax appears to reflect adaptations to different hydrodynamic regimes and geological separations between basins.

Ecogeographical Divergence in Morphological Female Traits of a Widespread Viviparous Lizard in Mexico

César A. Díaz‐Marín, Aurelio Ramírez‐Bautista, Uriel Hernández‐Salinas — Mon, 20 Oct 2025 08:34:42 -0700

ABSTRACT

Ecogeographic rules explain intra- and interspecific variation in the morphological and reproductive traits of animal species through the heat balance hypothesis, resource availability hypothesis, and dehydration resistance hypothesis. Here, we focused on determining whether populations of female Sceloporus grammicus could be classified by morphological and reproductive traits and whether there is a relationship with environmental temperature, precipitation, and aridity of their habitats according to the heat balance, resource availability, and dehydration resistance hypotheses. Our results showed that populations of female S. grammicus could be classified based on their morphological and reproductive traits. The first discriminant function, which corresponded to large heads and short forearms, was negatively correlated with environmental temperature. However, there was no relationship with precipitation or aridity index. Therefore, our results support the converse of Allen's rule, where short-limbed lizards are favoured in warm climates, whereas long-limbed lizards confer advantages in cold climates. This ecogeographical pattern could influence the physiological and locomotor performance of female S. grammicus in different ways and may represent a baseline for future research and conservation agendas.

Morphological Variability in Two Populations of Millipede Glomeris hexasticha Brandt, 1833 (Diplopoda: Glomerida: Glomeridae): Traditional and Geometric Morphometric Approaches

Thu, 02 Oct 2025 21:59:44 -0700

ABSTRACT

Environmental factors and human activities can affect the variation (at both inter- and intrapopulation levels) in the shape and size of various morphological traits, which play a role in behaviour, dispersal and reproductive strategies. Although inter- and intrapopulation morphological variation has been investigated in certain millipede species utilising both traditional and geometric morphometric methods, such research has not yet been conducted on glomerids. Therefore, this study aims to investigate morphological variation in specific traits at both mentioned levels in Glomeris hexasticha Brandt, 1833. Analysed individuals were collected from two populations in Belgrade, Serbia. Both traditional and geometric morphometric techniques were employed to assess morphological variability. Landmarks and semilandmarks were placed on the antennae, gnathochilariums, legs, collums, anal shields and telopods. Morphological variability was analysed using ImageJ, CoordGen, MorphoJ, and R program package. No significant interpopulation size differences in the analysed morphological traits were observed; however, significant sexual size differences were noted in both populations, with females being the larger sex. Shape variation was identified in some morphological traits at inter- and intrapopulation levels. The shape of the analysed morphological traits demonstrates greater phenotypic plasticity compared to the size of the same traits in G. hexasticha exposed to varying environmental pressures.

Morphology and Ultrastructure of Puye (Galaxias maculatus) Spermatozoa

Sat, 27 Sep 2025 06:09:14 -0700

ABSTRACT

This study characterises basic seminal and sperm parameters of puye (Galaxias maculatus maculatus), including sperm concentration, seminal plasma osmolality and cell viability. In addition, it provides a detailed description of sperm ultrastructure. Wild males (n = 21) were captured in southern Chile. A small and variable volume of milt was collected per male; the samples exhibited a high sperm concentration (55.84 ± 8.25 × 10⁹ spermatozoa mL⁻¹) and high viability (94.38% ± 2.78%). Spermatozoa had a total length of 26.9 ± 0.63 μm and consisted of an elongated head lacking an acrosome, a short mid-piece with ring-shaped mitochondrion, and a relatively short flagellum. The nucleus contained a deep nuclear fossa occupying almost the entire head, from which the flagellum emerged. The flagellum exhibits the classical 9 + 2 axoneme structure and consists of a long main piece and a short end-piece. The main piece presents a pair of side-fins of variable length, oriented in the plane of the central microtubules. This study provides the first detailed description of sperm ultrastructure in G. maculatus, revealing similarities with various fish families. This information could be valuable for future research on reproductive physiology, sperm evolution and potential applications in assisted reproduction and conservation.

Weaponry Investment in the Socially Monogamous Snapping Shrimp Alpheus brasileiro (Decapoda: Alpheidae)

Fri, 12 Sep 2025 08:00:47 -0700

ABSTRACT

Weapons are morphological structures used by animals in various contexts, especially in intra-specific contests and visual displays. In snapping shrimps of the genus Alpheus, particularly the monogamous species Alpheus brasileiro, both sexes bear enlarged chelipeds, potentially conferring advantages in mate competition or territorial defence. However, little is known about sex-specific weapon investment value (WIV) in socially monogamous species. This study investigated WIV in males and females of A. brasileiro through monthly sampling from April 2015 to March 2016 in a southeastern Brazilian estuary. Shrimps were measured for carapace and chela (propodus + dactyl) dimensions, and allometric analyses were performed to assess relative growth patterns. WIV was quantified by comparing the dry weight of the major chela to total body dry weight. Both sexes showed positive allometry for weapon growth, indicating increased energy allocation to chela development. However, males invested significantly more (≈26%) of their body weight in weaponry compared to females (≈20%). These findings suggest that males face stronger selective pressures favouring larger weapons, possibly due to intra-sexual competition, predatory defence or display behaviours. Our results provide new insights into sex-based differences in weapon development in Alpheus, emphasising the relevance of investigating morphological traits in socially monogamous crustaceans.

Morphology of Guard Hairs in Amazonian Marsupials: Intergeneric Variation, Habitat and Habit Association in a Phylogenetic Framework of the Order Didelphimorphia

Tue, 02 Sep 2025 05:30:19 -0700

ABSTRACT

The cuticle and medulla of guard hairs exhibit distinct morphological patterns among mammalian species. To investigate this variability in marsupials from the Brazilian Amazon, we analysed guard hairs from nine Didelphimorphia species and incorporated data from an additional 25 didelphid species. We examined how these patterns relate to habitats and habits and proposed phenotypic evolutionary hypotheses within Didelphimorphia. Furthermore, we provide the first descriptions for Philander pebas, P. canus and Didelphis imperfecta. No intraspecific variation was found in cuticle morphology or its relationship with habitats. However, conoidal and lozenge cuticular patterns may be associated with arboreal and terrestrial habits, respectively. While the microstructure of guard hairs is useful for genus-level identification of mammals, species-level identification in the diverse Amazonian marsupials remains challenging due to pattern repetition and the reliance on more subjective characteristics.

Crushing and Cutting: Shape Variation and Morphological Integration Between the Claws of Two Swimming Crab Species (Brachyura: Portunidae)

Fri, 22 Aug 2025 06:36:13 -0700

ABSTRACT

This study investigated shape variations and morphological integration between the components of crusher and cutter claws in two species of swimming crabs, Callinectes danae and Callinectes ornatus. The propodi and dactyli of the claws were analysed in males and females of both species, using geometric morphometric techniques to identify subtle shape differences and analyse the integration between the components. The analysis of morphological integration assesses the coadaptation between two correlated traits, whose modifications may result in improvements in functional performance. The crusher claws, associated with agonistic interactions and breaking prey with hard tissues, showed greater robustness than the cutter claws, which are specialised in cutting tasks and agile capture. Despite these functional differences, a high degree of morphological integration was found between the propodus and dactylus in both types of claws, regardless of sex or species. Statistical analyses confirmed significant differences in the shape of the structures between crusher and cutter claws, highlighting variations in robustness and proportions of the components. These findings indicate that, even though each type of claw is frequently used to acquire different resources, they do not differ in terms of morphological integration, as they are coadapted to perform different functions with high efficiency.

Histological Characteristics of Selected Organs of Pseudecheneis sulcatus

Wed, 13 Aug 2025 02:55:47 -0700

ABSTRACT

Pseudecheneis sulcatus, an omnivorous fish, is one of the protected species in the Binglangjiang basin. Through histological sections and microphotographic observation, this paper analyzes the histological characteristics of oesophagus, stomach, intestine, liver, kidney, eggs, barbels, and brain of P. sulcatus. The results show that P. sulcatus contains a short oesophagus with numerous goblet cells, a stomach with the muscularis mucosae and gastric glands, and an intestine with long and complex mucosal folds, corresponding to its omnivorous habit. The boundaries of hepatic lobules are indistinct, and the size of hepatocytes is large. The cerebellum is small, which is in line with its benthic living habits. The barbels of P. sulcatus have numerous taste buds while having fewer goblet cells. In addition, all the eggs of P. sulcatus collected in this survey are at stage III of development, indicating that it has the univoltine ovary. There is no significant difference in the kidney compared with other teleost fishes. This study enriches the basic biological content of P. sulcatus and provides basic data for its artificial reproduction and resource protection, thereby effectively protecting this species and the biodiversity of the Binglangjiang.

Morphometric and Paleobiological Insights Into Pleistocene Sicilian Wolf Populations

Domenico Tancredi, Carolina Di Patti, Sabrina Lo Brutto, Matteo Cammarata — Fri, 08 Aug 2025 06:49:49 -0700

ABSTRACT

The Pleistocene wolves (Canis lupus) from Sicily represent one of the few known insular populations of this species from that time period. Despite their potential relevance for understanding carnivore adaptations in insular contexts, no dedicated study has previously investigated their morphology and evolutionary significance. This study presents the first detailed analysis of Pleistocene wolf remains from Sicily, providing new insights into their morphometric variability and paleobiological implications. Fossil specimens from seven deposits in the north-western region of the island were analysed using a detailed morphometric approach, including log-ratio diagrams and principal component analysis (PCA). Estimates of body mass and shoulder height were also obtained through multiple regression equations. The results reveal considerable variability in size and dental proportions among the Sicilian specimens, which span the range documented in coeval peninsular Italian populations. Notably, some individuals from Arena Cave display divergent dental patterns and pronounced tooth wear, possibly reflecting ecological specialisation or early domestication processes. While preliminary, these findings underscore the complexity of wolf populations in Pleistocene Sicily and provide a foundation for future investigations into their evolutionary history and ecological adaptations.

Skull Shape Variation Among Domestic Duck Breeds and Their Wild Ancestor: Orvia, Pekin and Mallard

Wed, 06 Aug 2025 05:58:40 -0700

ABSTRACT

The skull is a critical structure for morphological characterisation across species and breeds, providing valuable insights into taxonomic classification and functional anatomy. This study aimed to investigate the cranial morphological variations among Orvia and Pekin domestic ducks and the wild Mallard (Anas platyrhynchos Linnaeus, 1758) using geometric morphometric methods. Furthermore, it examined whether these morphological characterisations could differentiate between domestic breeds and Mallard, and whether they exhibited allometric effects. In this study, the skulls of 59 one-year-old male ducks were analysed after slaughter. The skulls were modelled in 3D and subjected to geometric morphometric analysis. The results revealed significant differences in skull size among the Orvia, Pekin, and Mallard ducks (p < 0.001), with Orvia exhibiting the largest skull size. While overall shape differences were found among the duck groups, no statistically significant shape differences were observed between the Pekin and Mallard groups. The Orvia displayed broader skulls, whereas the Pekin and Mallard groups exhibited narrower and more elongated skull shapes. Additionally, a significant size-shape relationship was observed in the Pekin and Mallard groups, but no significant allometric relationship was found for the Orvia group. These findings contribute valuable insights into the morphological differentiation and anatomical understanding of domestic and wild ducks, offering a foundation for further comparative morphological studies.

Growth and Variation in Fallow Deer (Dama dama L.) From Two Contrasting Habitats in Southern Britain

Adrian M. Lister, Norma G. Chapman — Wed, 30 Jul 2025 01:24:57 -0700

ABSTRACT

We have compiled a unique data set on the age, sex, body weight and dimensions of over 500 European fallow deer from two contrasting areas of habitat in southern England: a high-density managed parkland population and a lower-density feral woodland one. We plot growth in body weight, shoulder height and bone dimensions against individual age, assessing sexual dimorphism and regional differences in growth from birth, the timing of cessation of growth and adult size. This variation can be related to differences in habitat, feeding, population density and season of death between the two populations. We highlight the biases inherent in body weight comparisons and contrast them with size comparisons based on postcranial bones. We also identify potential differences in bodily dimensions between the colour morphs of European fallow deer. Finally, we generate predictive equations enabling the estimation of sex, shoulder height and body mass from isolated metapodials, of value for relating fallow deer remains to palaeoenvironmental variation at archaeological and palaeontological sites.