Widely distributed but still poorly known – morphological study of <i>Evimirus uropodinus</i> (Parasitiformes: Eviphididae) nymphs and adults, using different observation methods

Currently, nine species are included in the genus Evimirus, with the widely distributed E. uropodinus (Berlese 1903), originally described from Italy (as Eviphis), the only representative of the genus in Europe. Other species of this genus, i.e. E. breviscuti Karg and Schorlemmer 2009; E. convergens (Berlese 1913); E. kargi Hirschmann 1975; E. leptogenitalis Karg 1979; E. minimus (Berlese 1920); E. pentagonius Karg 1996; E. pulcherpori Karg 1989 and E. scutellatus Halliday 2010, are known from Cuba, Java and India, New Guinea, Argentina, Java, New Caledonia, Saint Lucia (Lesser Antilles) and Australia, respectively. Females are the only instar reported so far for most of the described species. Males are known only in E. pentagonius and E. uropodinus, and juveniles were described exclusively in E. uropodinus. Although E. uropodinus seems to be the best-studied Evimirus species, the descriptions of its developmental stages require a thorough revision. Kaczmarek and Marquardt (2024) described in detail the E. uropodinus larva, combining light microscopy (LM) and scanning electron microscopy (SEM) observations. This study extends the analysis to all postembryonic stages of this species. In the present paper, we provide full data on chaetotaxy in E. uropodinus protonymphs, the first ever for this species and genus. Moreover, triplicity of apotele in all stages, sexual dimorphism of chelicerae, and differences in the ventral morphology between LM and SEM are discussed. Two pairs of pore-like structures, producing secretions in E. uropodinus nymphs and adults, are detected: (1) the poststigmatal, which opens close to the stigma; and (2) the anterodorsal pores, close to insertions of setae z2 and z4 in protonymphs and insertions of z2 and s1 in deutonymphs and adults. Secretion was experimentally triggered in males and females to observe the phenomenon and the accompanying behaviour. The current study establishes E. uropodinus as the most thoroughly described species of the genus.