Bioacoustics of Poecilimon vodnensis

Remarks: P. vodnensis shares the taxonomic characters of the P. zonatus species group, and is the only member which can be found in the Balkans. This species is closely related to P. zonatus zonatus , P. z. datca ssp. n. , P. variicercis , P. varicornis and P. salmani sp. n. , but differs from these species by having a wider fastigium, different shape of stridulatory organ, cerci and cercal apex in male, and different shape of pronotal disc in both sexes. P. vodnensis shares similar characters with P. variicercis , P. varicornis and P. salmani sp. n. by having distinct concave structure of the pronotal caudal margin. The calling song is also similar to that of the other members of the studied zonatus group excluding P. tauricola and P. azizsancar sp. n .. The male song may be distinguished by its general pattern, less impulse number and shorter duration of syllables. A male in July 1954 and a male and a female in August 1957 were initially discovered by Mladen Karaman in the Republic of Macedonia , on Mount Vodno at 900 m altitude, in an area with Rubus sp. ( Karaman 1958 ). Many subsequent researches in this area were carried out without any results. It is likely that anthropogenic changes of this mountain located on the outskirts of Skopje contributed to its rarefaction. The species was found recently, but in the south of the country, near Prilep , in two different localities at less than ten kilometres from each other ( Lemonnier-Darcemont & Darcemont 2016 ): 1. Pass above Štavica: 41°15'04.3" / 021°35'20.9" at 1147 m a.s.l. Meadow with some thorn bushes including Rosa sp., in edge of beech groves. Nearly twenty taxa were also recorded including Bradyporus dasypus, Pholidoptera macedonica, Montana macedonica, Poecilimon ornatus , Metrioptera tsirojanni, Celes variabilis, Stenobothrus fischeri, etc . 2. Between Dunje and Manastir villages: 41°13'04.0" / 021°41'24.6" at 590 m a.s.l. Grazed dry grassland on the edge of open oak forest (opened artificially). The population of Orthoptera is diversified and rich, including the presence of Saga rammei , S. natoliae , B. dasypus , P. ornatus, Arcyptera microptera, Stenobothrus fischeri, etc. These biotopes, which have in common the proximity of deciduous forests, are located on the collinean level. It should be also noted that the individuals have always been observed in areas where the herbaceous layer was the densest and the highest. The period of occurrence of adults is between the end of May and the end of June, but as Karaman's observations showed, some adults could still be visible until July–August in Vodno Mountain. In the area of Prilep , we have never found adults so late which seems logical given the much more xerothermophilic character of these two localities. This species is in “Near Threatened” status in the IUCN Red List of Threatened Species (2017–3) and in the European Red List of Orthoptera ( Hochkirch et al . 2016 ) . Breeding notes (2017) : for the majority of individuals collected on May 20 at the Stavica locality ( 1150 m ), the last moult occurred between the 28th of May and the 2nd of June. Two to three days later the males began to stridulate and the mating activities began. According to this first breeding experience, the sexual maturation seemed fast, and the survival rate after first mating for males or females was rather low, not exceeding one week.

Remarks. Detailed morphological and acoustic descriptions, with rich illustrative material, were given by Karaman (1958) and Sevgili et al. (2018) . Our song recordings of male-female duets provided in addition to the data by Sevgili et al. (2018) , reveal two types of male song (either of single syllable or groups of two syllables) (Fig. 11 ). The main, first, or single, syllable has 2–4 impulses (rarely up to 7) and lasts 5 to 16 ms. The second syllable was measured with 3 to 9 impulses and lasted 7 to 14 ms. Together the two-syllable groups had a duration of 34–82 ms. Male song of two syllable types is represented within the two subgroups of P. zonatus group and was reported for P. azizsancar and P. variicercis ( Sevgili et al. 2018 ) , as well as is common for the Poecilimon jonicus group (e. g., Borissov et al. 2020 , 2023 ). The female song consists of a first part of one or, more frequently, two impulses, and of a second part consisting of a few impulses with lower energy or a quiet ‘ buzz’ (compare Fig. 11 – B and C). The first part of two impulses lasts 5–11 ms, while the whole song if the second part is present lasts ca. 40–60 ms. The latency times for the female response measured from the beginning of the male song was 27–39 ms (the latency lasts longer when there is one impulse in the first part of the female response). Table 3 provides additional characteristics of the species song.