Zoodiversity

Scanning Electron Microscopy Provides a Novel Method to Map Abdominal Musculature in Archaeognatha (Insecta)

N. Matushkina — 2025-10-08

Using scanning electron microscopy, previously overlooked cuticle modifications were revealed in the attachment points of skeletal musculature of Trigoniophthalmus simplex (Insecta, Archaeognatha, Machilidae). These findings demonstrate that SEM may serve as an indirect approach for rapidly and precisely mapping complicated abdominal musculature of Archaeognatha. The reference to Archaeognatha is especially relevant for the mapping of the abdominal muscles in insects in the sense of the presence of a hypothesized plesiomorphic sclerite composition in this group of wingless insects.

When Morphology Meets Molecules: Barcoding Confirms an Ancient Separation of Phytoecia tigrina subspecies (Coleoptera, Cerambycidae)

A. Zamoroka — 2025-10-02

The molecular analysis of Phytoecia tigrina revealed substantial genetic differentiation (5.8–7.0 %) between populations on opposite sides of the Carpathian Arc. Two distinct haplogroups were identified: PhtZk (western, haplotype PhtZk-1) and PhtPo (eastern, haplotypes PhtPo-1 and PhtPo-2), including the type locality of Phytoecia tigrina podillica Zamoroka, Ruicănescu& Manci, 2024. These findings support the division of Ph. tigrina into two subspecies. The pronounced genetic divergence suggests that the separation between Ph. tigrina tigrina and Ph. tigrina podillica, occurred much earlier than previously assumed. Moreover, the coexistence of two highly distinct haplotypes within Ph. tigrina podillica populations suggests episodes of rapid range expansions and contractions during the Late Pleistocene and Holocene. Overall, our results provide valuable insights into the evolutionary processes driving intraspecific diversification in Ph. tigrina in response to cyclical climate fluctuations.

Whether the Presence of Di- and Triploid Hybrids, Pelophylax esculentus, Influences Gametogenesis of Their Parental Species, P. ridibundus

E. Pustovalova — 2025-09-01

Meiosis ensures efficient reproduction by the formation of viable gametes with a constant number of chromosomes. However, in natural hybrid complexes, where parental and hybrid lineages coexist, the fidelity of this process may be challenged. To better understand how this process functions in natural populations, we investigated, for the first time, the features of spermatogenesis and assessed the level of abnormal meiotic metaphases in the parental species Pelophylax ridibundus and P. lessonae of the hybridogenetic P. esculentus complex from 11 locations in Ukraine. Using Giemsa and/or Ag staining, we analysed 2,203 meiotic and 471 mitotic metaphases from 41 males. Most of the analysed spermatogonia and spermatocytes had chromosome numbers consistent with those forming viable gametes. The average level of aneuploidy in P. ridibundus males was 17% across all hemiclonal population systems analysed, which is significantly lower than in hybrids (p < 0.05). Furthermore, the lack of a significant difference (p = 0.93) in aneuploidy frequency among P. ridibundus from different population systems compared to the pure R-population suggests that the spermatogenesis of P. ridibundus is not affected by the presence of hybrids or the other parental species (P. lessonae). This cytogenetic robustness may contribute to the long-term stability of mixed populations, where P. ridibundus serves as a consistent source of haploid gametes necessary for the reproduction of P. esculentus hybrids.

Risk Assessment of Introduced Fish Species as a Biodiversity Mitigation Effort in Lake Toba, North Sumatra, Indonesia

A. S. Batubara — 2025-09-01

Lake Toba's environment and ichthyofauna are degrading due to human activities and the introduction of invasive fish species. Studies are needed to identify species, distribution patterns, densities and risks of introduced fish species, and these studies must be conducted using scientific and measurable approaches. Research was conducted in Lake Toba, North Sumatra, Indonesia, from June to August 2024, at ten research locations. The research employed an exploratory method, measuring parameters such as population density, the Shannon-Wiener diversity index (H'), the evenness index (E), and the Simpson dominance index (C). Furthermore, this research measures the risk of invasiveness using the Fish Invasiveness Screening Test (FIST). Nine introduced fish species have become established in Lake Toba, including Amphilophus labiatus (Günther, 1864), Aplocheilus panchax (Hamilton, 1822), Cyprinus carpio Linnaeus, 1758, Mystacoleucus padangensis (Bleeker, 1852), Oreochromis mossambicus (Peters, 1852), O. niloticus (Linnaeus, 1758), Poecilia reticulata Peters, 1859, Puntigrus tetrazona (Bleeker, 1855), and Xiphophorus helleri Heckel, 1848. Population density values show that P. reticulata has the highest average value reaching 6.02 ind/m², followed by A. labiatus 2.21 ind/m², M. padangensis 0.21 ind/m², O. niloticus 0.14 ind/m², P. tetrazona 0.08 ind/m², X. helleri 0.03 ind/m², and 0.01 ind/m² in A. panchax, C. carpio, and O. mossambicus, respectively. Diversity index analysis show low diversity (mean of 0.7), evenness index shows unstable community (mean of 0.46), and Simpson dominance index shows the presence of a dominant species (mean of 0.63). The results of the FIST analysis show that five introduced fish species are in the high risk category, three species have a moderate risk and one species has a low risk. O. niloticus, A. labiatus, C. carpio, O. mossambicus, and P. reticulata have a high risk for ichthyofauna diversity and in fact cause low diversity in Lake Toba.

A Survey of Helminths of the Marsh Frog, Pelophylax ridibundus (Amphibia, Ranidae) and the First Record of Ophiotaenia saphena (Cestoda, Proteocephalidae) in the Ukrainian Part of the Danube Delta

O. Greben — 2025-08-19

In 23 examined marsh frogs, Pelophylax ridibundus (Pallas, 1771), from the town of Vylkove (Odesa Region, Ukraine), 25 helminth species were found. Helminth infracommunities in the studied frogs comprised 3–14 species (mean 9.4; median 10.0) and intensity of infection ranged from 20–351 (mean 151; median 155). Six helminth species were classified as predominating in the helminth component community based on their prevalence and abundance: the nematode Oswaldocruzia duboisi Ben Slimane et al., 1993, the cestode Ophiotaenia saphena Osler, 1931, the trematodes Diplodiscus subclavatus (Pallas, 1760), Prosotocus confuses (Looss, 1894), Pleurogenoides medians (Olsson, 1876), and Tylodelphys excavata (Rudolphi, 1803) (metacercariae). The nematodes Icosiella neglecta (Diesing, 1851) and Os. duboisi and the cestode Op. saphena are reported for the first time in marsh frogs from Vylkove. The latter species is known as a parasite of true frogs (Ranidae) in North America and was recently discovered in Pelophylax spp. in Greece and Romania. It is first reported in Ukraine and is regarded as an invasive alien parasite of P. ridibundus in the Ukrainian part of the Danube Delta. The morphological description and molecular characterisation of Op. saphena from the new locality are provided.