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The presence of morphological integration and modularity of the forcipular apparatus, despite its evolutionary significance, has not been analyzed in centipedes. This morphological structure has a crucial role in feeding and defense, thanks to its poisonous part (forcipules), which is important for catching the prey. The aims of our study were: i) to test the hypothesis of modularity of the forcipular apparatus in centipede Lithobius melanops; and ii) to investigate the influence of allometry on overall morphological integration in the aforementioned species using a geometric morphometric approach. The presence of fluctuating asymmetry was obtained by Procrustes ANOVA. Allometry was significant only for the symmetric component of the forcipular apparatus. The modularity hypothesis was not accepted, because the covariance coefficients for symmetric and asymmetric components were lower than 89.5% and 72.1% (respectively) of other RV coefficients obtained by a random contiguous partition of the forcipular apparatus. Results of the present study indicate that allometry does increase the level of morphological integration in the forcipular apparatus. According to our results, the forcipular coxosternite and forcipules could not be considered as separate modules; namely, they probably share similar developmental pathways and function in different forms of behavior and survival in L. melanops.

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Covariation of multiple morphological traits and modularity have been widely studied in the field of evolutionary developmental biology. Subunits of a morphological structure can evolve separately from each other in a modular fashion. The aims of our study therefore were: i) to test the hypothesis of modularity in the dorsal part of the head capsule and the gnathochilarium separately during late postembryogenesis in the julidan millipede Megaphyllum unilineatum (C. L. Koch, 1838) using geometric morphometrics; and ii) to investigate the influence of allometry on overall morphological integration in the dorsal part of the head capsule and the gnathochilarium in the mentioned species. Individuals from different ontogenetic stadia (stadium VI - stadium XI) were included in the analyses. Significant influence of fluctuating asymmetry on the dorsal part of the head capsule shape was detected by Procrustes ANOVA. Regressions were significant for the symmetric component of both analysed morphological traits, while non-significant regression was detected for the asymmetric component of the head capsule's dorsal part. Hypotheses of modularity for the dorsal part of the head capsule and the gnathochilarium are rejected because our results indicate that a small proportion of alternate partitions has higher covariation between subsets of structure than between the hypothesized modules. Contrary to our expectations, results of the present study show that allometry does not increase the level of morphological integration in the dorsal part of the head capsule and the gnathochilarium in M. unilineatum. Based on the obtained results, we conclude that the dorsal part of the head capsule and the gnathochilarium are not composed of independent modules and that in the case of the capsule's dorsal part, developmental processes affect morphological integration in different ways at different levels of shape variation.

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Until now, morphological trait variation has been investigated in several millipede species using geometric morphometrics. The present study is the first attempt to explore sexual shape and size dimorphism (SShD and SSD) of morphological structures in Polydesmida. We here analyse antennal, head, and leg SShD and SSD in Brachydesmus troglobius Daday, 1889. Our results show that SSD exists in all of the analysed structures, while SShD is present only in the legs. In comparison with females, males possess longer and wider legs, as well as longer antennae and a shorter head. Contrary to previous findings in some Julida, in B. troglobiusSSD of the antennae and legs varies more than SShD in these morphological structures.

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Members of the millipede order Julida rely on dominantly quinonic defensive secretions with several minor, non-quinonic components. The free radical-scavenging activities of ethanol, methanol, hexane, and dichloromethane extracts of defensive secretions emitted by Pachyiulus hungaricus (Karsch, 1881) and Megaphyllum unilineatum (C. L. Koch, 1838) were investigated using the ABTS, DPPH, and total reducing power (TRP) tests. The obtained extracts were also tested for inhibition of acetylcholinesterase and tyrosinase activity. Finally, the antifungal potential of both julid extracts was evaluated against seven Fusarium species. Secretions of both species showed activity against free radicals, acetylcholinesterase, tyrosinase, and all of the selected fungal species. The secretions of P. hungaricus exhibited a more potent antioxidative effect than did those of M. unilineatum, while there were no significant differences of antiacetylcholinesterase activity between the tested extracts. Only the hexane extract of M. unilineatum showed an effect on tyrosinase activity stronger than that of P. hungaricus. Fusarium sporotrichioides, F. graminearum, and F. verticillioides were the fungi most resistant to secretions of both julids. The Fusarium species most susceptible to the secretion of P. hungaricus was F. avenaceum, while the concentrations of M. unilienatum extracts needed to inhibit and completely suppress fungal growth were lowest in the case of their action on F. lateritium. Our data support previous findings that julid defensive secretions possess an antimicrobial potential and reveal their antioxidative and antineurodegenrative properties. Bearing in mind the chemical complexity of the tested defensive secretions, we presume that they can also exhibit other biological activities.

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The chemical defence of the millipede Pachyiulus hungaricus is reported in the present paper, in which a chemical characterization is given and antimicrobial activity is determined. In total, independently of sex, 44 compounds were identified. All compounds belong to two groups: quinones and pentyl and hexyl esters of long-chain fatty acids. The relative abundances of quinones and non-quinones were 94.7% vs. 5.3% (males) and 87.3% vs. 12.7% (females), respectively. The two dominant quinones in both sexes were 2-methyl-1,4,-benzoquinone and 2-methoxy-3-methyl-1,4-benzoquinone. Antibacterial and antifungal activity of the defensive secretion was evaluated in vitro against seven bacterial strains and eight fungal species. With the aid of a dilution technique, the antimicrobial potential of the secretion and high sensitivity of all tested strains were confirmed. The lowest minimum concentrations of these compounds (0.20-0.25 mg/mL) were sufficient for inhibition of Aeromonas hydrophila, Listeria monocytogenes and Methicillin resistant Staphylococcus aureus (MRSA). The growth of eight tested fungal species was inhibited by slightly lower concentrations of the secretion, with Fusarium equiseti as the most sensitive fungus and Aspergillus flavus as the most resistant. Values of MIC and MFC in the employed microdilution assay ranged from 0.10 to above 0.35 mg/mL. The given extract contains antimicrobial components potentially useful as therapeutic agents in the pharmaceutical and agricultural industries.

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