Several morphological structures useful for taxonomy have been identified and described in the immature stages of Lepidoptera. In Lycaenidae, the integument of larvae and pupae has received particular attention because it bears specialized organs and setae involved in interactions with ants. However, significant gaps remain in the descriptions of immature stages for many species, especially regarding these specialized structures. Here, scanning electron microscopy (SEM) images of pupal exuviae are presented, including descriptions of dendritic setae and other setal types, the pore cupola organs (PCOs), and the stridulatory region on the abdomen of five Strymonina Tutt, 1907 genera: Arawacus Kaye, 1904; Panthiades Hübner, 1819; Heterosmaitia Clench, 1964; Strymon Hübner, 1818; and Thereus Hübner, 1819. Seven pupal exuviae from six species were examined, focusing on abdominal segments A1–A6. Different types of setae were recorded on the abdominal integument. All specimens exhibit a consistent pattern of setae surrounding spiracles A2–A5, which remain stable within each species. In contrast, the setae surrounding spiracle A6 were dendritic and varied among species. Of the two types of PCOs observed, both are present only in Strymon bubastus (Stoll, 1780). The pupal exuviae structures described here enhance the understanding of pupal morphology and suggest that Arawacus ellida (Hewitson, 1867), Panthiades hebraeus (Hewitson, 1867), Heterosmaitia marius (Lucas, 1857), S. bubastus, Strymon mulucha (Hewitson, 1867), and Thereus ortalus (Godman and Salvin, 1887) exhibit myrmecophily during the pupal stage. This study demonstrates that pupal exuviae are a promising material to access the morphology of immature Lepidoptera.
Stingrays exhibit a wide diversity of reproductive strategies and modes of embryonic nutrition, yet comprehensive morphological descriptions of the female reproductive system remain scarce for many marine species. The present study characterizes in detail the macroscopic and microscopic morphology of the female reproductive tract of the marine stingray Hypanus guttatus, collected from an Amazonian estuary in northern Brazil. Four sexually mature non-gestational females (disc width 70.125 ± 3.79 cm, disc length 187 ± 5.77 cm) were subjected to anatomical dissection and histological analysis. The reproductive system exhibited marked functional asymmetry, characterized by complete development of the left antimere (ovary, oviduct, oviducal gland, uterus, and urogenital sinus) and severe regression of the right antimere, which retained only vestigial structures associated with the epigonal organ. The functional left ovary displayed an organizational pattern typical of matrotrophic viviparous elasmobranchs, containing follicles at various developmental stages indicative of asynchronous oogenesis. The genital duct exhibited histologically well-differentiated regions, including a specialized oviducal gland, a uterus lined with trophonemata, and a urogenital sinus. This structural pattern aligns with the reproductive anatomy described for marine Myliobatiformes, in contrast to the bilateral functionality reported for several freshwater stingray species. This study provides the first integrated morphological characterization of both antimeres in Hypanus guttatus, expanding current knowledge on the reproductive biology of Neotropical estuarine batoids and establishing an anatomical baseline for future ecological, physiological, and conservation research.
Terrestrial gastropods are highly sensitive to environmental conditions, yet the influence of photoperiod on growth allocation and reproductive performance remains poorly documented in tropical Achatinidae. This study investigated the effects of contrasting light-dark cycles on growth dynamics, shell development and reproductive activity in two giant African land snails, Achatina achatina and Archachatina ventricosa, maintained under controlled laboratory conditions for 66 days. Individuals were exposed to short-day (6 L:18D), balanced (12 L:12D) and long-day (18 L:6D) photoperiod regimes. Body mass was monitored every two days, whereas shell morphometry and reproductive activity were assessed throughout the experiment. Longitudinal mixed-model analyses revealed significant temporal changes in both body mass and shell growth trajectories, with strong interactions between photoperiod, species and experimental time. Body mass increased progressively under all photoperiod conditions, although growth trajectories differed according to species-specific responses. In contrast, shell growth exhibited stronger sensitivity to photoperiodic conditions. A. achatina displayed enhanced body mass gain under long-day conditions but reduced shell growth, whereas A. ventricosa exhibited higher shell growth and reproductive activity under short-day conditions. Egg production was markedly reduced under the 18 L:6D regime in A. ventricosa. Integrated biological response profiles further highlighted contrasting allocation strategies between somatic growth, shell development and reproduction according to both species and photoperiod. Survival remained high throughout the experiment regardless of treatment. Overall, these findings demonstrate that photoperiod acts as an important ecological regulator of growth and reproductive allocation in tropical terrestrial snails and suggest species-specific photoperiodic strategies within Achatinidae.
In Brachyura, reproduction involves a range of behavioral, morphological, and physiological mechanisms that contribute to reproductive success. The land crab Johngarthia lagostoma, endemic to four oceanic islands in the South Atlantic, shows no clear pre- or post-copulatory guarding behavior, and the mechanisms involved in sexual selection remain uncertain. This study investigated the ontogenetic development of the first gonopod using relative growth analyses and high-resolution imaging techniques, with special emphasis on the corneous unguis, a distal non-calcified structure of unknown function. Morphometric analyses were performed using carapace width as the independent variable and measurements from different gonopod regions, including the corneous unguis, as dependent variables. Relative growth was evaluated using power function, and growth shifts were estimated from the intersection between juvenile and adult growth phases. Nano-computed tomography and X-ray analyses were used to describe the overall morphology of the gonopod and provided detailed visualization of its distal region, including the horny claw and associated setae field. Most biometric relationships showed growth shifts at similar sizes (50–55 mm CW). In contrast, the corneous unguis showed a delayed ontogenetic transition (64.9 mm CW), indicating a developmental trajectory distinct from that of the other gonopod regions. The coordinated maturation of most gonopod regions, together with the delayed development of the corneous unguis, indicates differential developmental timing among components of the copulatory apparatus. Although the functional role of the corneous unguis remains uncertain, its distinct ontogenetic pattern supports the hypothesis that it may be involved in post-copulatory reproductive processes associated with sperm transfer and/or ejaculate processing.
The external morphology and ultra-surface structures of the oromandibular area (comprising of barbels and lips); and paired fins (pectoral and pelvic) have been studied for the first time in a hill stream fish Schistura multifasciata (Day, 1878) recorded from a semi-torrential hill stream Basistha, at Guwahati city, Assam, India. Schistura is one of the most adaptive Asian fish species dwelling in hill streams, mostly preferring a semi-torrential habitat. The aim of the study is to document the morphological peculiarities present in Schistura multifasciata that enable such hill stream fishes thrive in semi-torrential habitats. The study was conducted with mature individuals of this species using standard protocols of experimentation. The oromandibular area and paired fins were initially studied under a light microscope; and were further analysed under the Scanning Electron Microscope. The study has helped in revealing peculiarities in the ultra-surface structures of the oromandibular area and paired fins of Schistura multifasciata; that defines their differential adaptation strategies. Cumulative action of Type I II taste buds, microvilli, mucous pores, microridges, unculi; and papillated outgrowths present in the oromandibular area and paired fins of this species helps in effective adaptation to hill stream habitats; and this is the major highlight of this study.
