Systematics and bioacoustics of the Poecilimon sanctipauli-group ( Orthoptera : Tettigonioidea : Phaneropteridae )

In this paper a combination of characters by which Poecilimon species (Orthoptera: Tettigonioidea: Phaneropteridae) can be recognised as members of the P. sanctipauli group are described. Most important are the wide fastigium, short ovipositor and song characters. The morphological characters are figured and described (Table 1), and the song patterns illustrated by oscillograms. The proposed phylogenetic relationships of the members of this group are written as [P. mytilenensis (P. pulcher, P. lodosi, P. sanctipauli)]. All species of the group are known from southwest Turkey and some east Aegean islands. The three species P. pulcher, P. lodosi and P. sanctipauli are morphologically and bioacoustically quite similar. P. sanctipauli and P. pulcher are distinct species, P. lodosi, however, possesses a combination of the key characters of the other two species. It may be a relict species or, in our opinion more probably, a species of hybrid origin.


INTRODUCTION
The genus Poecilimon is one of the most species-rich genera of Orthoptera in the Palearctic.Like the other members of the subfamily Barbitistinae all species are micropterous and unable to fly.This fact is certainly in part responsible for the high number of species.The phylogenetic relationships within this huge genus (about 120 species), however, are not well understood.Ramme (1933) published the first revision of Poecilimon, establishing 8 groups for the 68 species known at that time.However, he made no attempt to clarify the relationships between the groups and between the species within the groups.Bey-Bienko (1954) recognized 73 species in this genus and presented a key and detailed re-descriptions of especially the Russian and Anatolian species.Because he stated that Ramme's groups were largely artificial, he abandoned the attempt to divide the genus into groups.Thirty years later, Heller (1984a) presented a cladogram of the relationships of 35 European forms using apomorphic characters.For a better understanding of the evolution of the genus, however, knowledge of the phylogenetic position of more of the species is necessary.In addition to conventional morphological characters it is now appreciated that bioacoustic data can help clarify the relationships of species and subspecies.Besides characters of the song pattern the structures used for sound production (male stridulatory file, size of female tegmina) and for hearing (size of prothoracic auditory spiracles) are also important for the identification and grouping of species (Heller, 1984a(Heller, , 1988;;Willemse & Heller, 1992;Heller & Lehmann, 2004).
Because of the large number of species involved, we concentrate on identifying and studying small monophyletic groups and clarifying the relationships of the species within these groups (e.g.Lehmann, 1998;Heller & Lehmann, 2004).
In the present paper we focus on a small group of species near P. sanctipauli Brunner von Wattenwyl, 1878. Ramme (1933) placed this species in a subgroup of his group V together with P. pulcher and P. mytilenensis.P. lodosi, described by Harz (1975), also belongs to this group (see below).All species of this group are known from southwest Turkey and some east Aegean islands.
At DORSA the localities (except some from Turkey) of all specimens in CH can be visualised by a web-based GIS mapping tool (including lat/long data).At SysTax the digitised sound recordings of many specimens are available.
Morphological structures were examined and measured using an Olympus stereomicroscope.For sound recording in the field an Uher tape recorder 4200 IC with a Uher M645 microphone was used (frequency response flat up to 20 kHz), in the laboratory a Racal store 4 D tape recorder with Brüel & Kjaer 4133 and 4135 microphones (frequency response flat up to 40 resp.70 kHz).Oscillograms and sound analysis were made using a PC and the programs Turbolab (Stemmer AG) and CoolEdit.Wing movements were recorded by an opto-electronic device (Heller, 1988).The stridulatory files were studied using scan-ning electron microscopes Autoscan, Fa.ETEC SEM, and DSM 960, Fa.Zeiss.
Bioacoustic terminology: Calling song: spontaneous song produced by an isolated male.Syllable: the song produced by one opening-closing movement cycle of the tegmina.Impulse: a simple, undivided, transient train of sound waves generated by the impact of one tooth of the stridulatory file.

Characteristics of the Poecilimon sanctipauli-group
From a direct comparison of most European and Anatolian Poecilimon species (e.g., Heller, 1984aHeller, , 1988;;Willemse & Heller, 1992;Heller & Reinhold, 1992;Lehmann, 1998;Sevgili, 2001;Heller & Lehmann, 2004;Heller et al., in press) and the literature, it became evident that a group of species of this genus can be separated and recognised by the following characters: 1. Fastigium wider or as wide as scapus.
3. Relatively large to medium body size compared to other Poecilimon species.
Members of the Poecilimon sanctipauli-group are recognised by a combination of characters [especially ( 1) and ( 2)].None of these characteristics can be considered as a unique autapomorphic character, some are probably even plesiomorphic characters.The evolution of the wide fastigium ( 1) is difficult to evaluate.The same variation in fastigium width is also found in the closely related genus Isophya.In Poecilimon, however, a wide fastigium is found only in the P. sanctipauli and P. ornatus/affinis groups.In addition, there are two small Poecilimon species in Turkey, P. glandifer Karabag, 1950 andP. ataturki Ünal, 1999, with wide fastigia (see Ünal, 2003), but they belong to a group with mute females, possibly the P. ampliatus group (Heller & Lehmann, 2004).The P. sanctipauli and P. ornatus/affinis groups show many similarities, but also distinct differences.One important difference is the length of the ovipositor (2).The ratio hindfemur to ovipositor is always below 2 in the P. ornatus/affinis group and above 2 in the P. sanctipauli group (data for the P. ornatus/affinis group used mean values from Harz, 1969).A short ovipositor, however, is also found in other groups of Poecilimon, and its evolution is again difficult to evaluate.It may be an adaptation to climate and change quite fast (see Heller et al., 2004).Body size (3) is another character difficult to assign as either an apomorphic or plesiomorphic state.The characters (4)-( 5) are connected with communication and are plesiomorphic characters for the P. sanctipauli group and present in a relatively large number of Poecilimon species.Stumpner & Heller (1992) give a description of the differences in spiracle size in Poecilimon and of the consequences for hearing.A two-phase stridulatory movement (6) was assumed to be an apomorphic character for a large group of Poecilimon species by Heller (1984a).This group includes the P. ornatus/affinis and P. sanctipauli groups.Most members of both groups share a calling song consisting of syllables with many impulses (7).It may be that the P. sanctipauli group is part of the P. ornatus/affinis group occurring in the south-east.However, a preliminary DNA study of Poecilimon lodosi, a member of the P. sanctipauli group, indicates it falls outside the very widely defined P. ornatus/affinis group.In any case, the species with the above-mentioned combination of characters belong together.
Isophya isidori: Giglio-Tos 1914: 4 (description); Ramme, 1951: 137 (not to Isophya); Harz, 1969: 740 (species incertae sedis); Willemse, 1984: 30 (reference) ;Heller, 1984b: 75 ( Diagnosis/description.See Table 1-2 and Figs 1-4.Song.The calling song of the male consists of isolated syllables produced at intervals of several seconds.Each syllable consists of two separate impulse groups.The first long and crescending syllable results from the slow closing movement of the tegmina at the beginning, the second much shorter one from the fast final closure at the end of the movement cycle (Fig. 8; see also Heller & Helversen, 1986;Heller, 1988).From the knowledge of the stridulatory movement and the structure of the stridulatory file it is possible to predict the process of sound production.During the first part of the syllable the scraper moves along the long outer part of the file, then probably stops at the bulge (Fig. 5), and finally moves along the short proximal part of the file.Since the song is difficult to characterise by measurements, an example of the intra-population variability in amplitude modulation is shown in Fig. 9.In the recordings of 15 animals the twopart syllable structure is easily recognised.The duration of the syllable depends on temperature and is about 500 ms at 25°C.In the course of the afternoon the syllables become longer and of the morning shorter (Fig. 9).
A female responds to male song by abruptly closing her tegmina, producing one or a few impulses (Heller & Helversen, 1986).A schematic figure of the position of the non-homologous stridulatory organs in males and females of P. sanctipauli can be found in Heller & Helversen (1986).
Song.The song is very similar to that of P. sanctipauli (see Fig. 7), also in syllable duration.The songs of some animals reared in the laboratory and in permanent acoustical contact with other males sometimes contained irregular intra-syllable gaps and impulse series after the second part of the syllable, perhaps some kind of rivalry song.Females responded to male songs in the same way as those of P. sanctipauli.Previous records.TURKEY: Manisa: Manisa Harz, 1975, (Önder et al., 1999: unrecognized paratype).
Discussion.This species has a combination of characters from P. pulcher (morphology) and P. sanctipauli (song).Currently it is impossible to identify dead specimens unambiguously as either P. pulcher or P. lodosi.We follow the hypothesis that P. lodosi is a local form occurring in Sipil Dagh, Manisa (see below: Discussion), but this needs to be confirmed by recording the songs of individuals from other populations of P. pulcher.

Poecilimon mytilenensis Werner, 1932
P. mytilenensis mytilenensis Werner, 1932: 297 Type locality: Greece, Lesbos (Mytilene).This species was revised by the authors together with Fer Willemse (Heller et al., 2005).Details of the synonymy and localities can be found in that paper.
Diagnosis/description.See Table 1 and Figs 1-4.Song.In both subspecies the male calling song does not consist of isolated syllables as in the other three species, but of sequences of 25-120 syllables with a duration of 10-30 s (Fig. 6; rarely as short as 6 s; all data recorded at ca. 25°C).Each syllable has two parts, which are more equal in duration than in P. sanctipauli (Fig. 8) Correspondingly the bulge in the stridulatory file is situated near the middle (Fig. 5).Females respond acoustically to male song (see Heller et al., 2005 for details).

Phylogeny
The three large species P. pulcher, P. lodosi and P. sanctipauli form a monophyletic group according to their morphological similarity and unique, derived type of bioacoustical signals.Making the additional assumption that a broad or even distally widened cercus apex (Fig. 2 D-H) in the male is an autapomorphic character of the group results in the following phylogenetic tree will: [P.mytilenensis (P.pulcher, P. lodosi, P. sanctipauli)].However, there are several alternative relationships for the three large species.The form of the cerci and subgenital plate of P. sanctipauli and the extremely slow stridulatory movement of P. pulcher can be considered as autapomorphic characters.In P. lodosi both these characters are in a plesiomorphic state.This species can be grouped with either of the two derived species, and can be considered a relict of the ancestral form.Alternatively, P. lodosi could be a hybrid between P. sanctipauli and P. pulcher.This is supported by the observation that there is only one known locality for P. lodosi, which is situated within (P.sanctipauli) or at the edge (P.pulcher) of the ranges of the other two species.P. pulcher and P. sanctipauli some- times occur very close together (same locality names with same or different collectors: Bergama, Selçuk, Kemalpasa, Seferihisar, Menemen, Boz Dagh).Considering their broad habitat requirements both species probably occur syntopically, but none of these localities have been examined for hybrids.At Sipil Dagh, the locality of P. lodosi, neither of the other two species were observed.Possibly at this locality both parent species met and the isolation barriers broke down resulting in the large hybrid population called P. lodosi.Hybridization occurs quite frequently when previously geographically separated forms meet.Closer examination sometimes shows that there is a complex pattern of local hybridization and syntopic co-existence of both forms.Mosaic hybrid zones with local break down of the isolation barriers between closely related species are reported in Orthoptera with increasing frequency as knowledge of these insects increases (e.g., acridid grasshoppers: Stumpner & Helversen, 1994;Ingrisch, 1995;Vedenina & Helversen, 2003;Bailey et al., 2004;crickets: Britch et al., 2001).

Biogeography
In the range of the genus Poecilimon, species of the P. sanctipauli group occur near to the south-eastern edge, an area with a high diversity of species (see Çıplak et al., 1993, 1999).They may have originated from a more widespread species, possibly a southern representative of the Balkan P. ornatus/affinis group (see Results).If this is correct the separation of the P. sanctipauli-group from its relatives may have occurred between the middle and late Miocene (Welter-Schultes & Williams, 1999; Langhian to Messenian, 16.5 to 6.5 mio years ago, possibly around the Serravalian-Tortonian boundary 11 mio years ago (Dermitzakis, 1990)) when the sea flooded into the Aegean.According to preliminary DNA studies species of Poecilimon may be relatively old with divergence within groups of closely related species estimated to have occurred 8 million years ago (Lehmann, 1998).The sequence differences between P. lodosi and species of the P. ornatus/affinis group are not smaller than the ingroup differences (same gene; Pollmann & Reinhold, unpubl.).As a first step in speciation, a northern form (today P. mytilenensis) may have separated from a precursor of the southern species P. sanctipauli, P. pulcher and P. lodosi, as indicated by their present day distribution (Fig. 10) and differences in song and morphology.The occurrence of P sanctipauli on many Aegean islands as well as on the main land is not unexpected since even as recently as the pleistocene and before there were land bridges to and between the islands, and them and the mainland.However, P. sanctipauli is found also on the island of Nisyros, a volcanic island risen above sea level not more than 1 mio years ago and never connected with the mainland (Papanikolaou & Lekkas, 1991).From these informations it is more surprising that P. mytilenensis is restricted to the islands of Lesbos and Alibey.However, the coastal mainland north of Izmir seems to be either generally poor in species (climatic reasons?) or less well studied (see distribution maps in Çıplak et al., 1993).Other details of the distribution pattern of the species, however, are more difficult to understand.Currently we cannot explain the distribution of the two subspecies of P. mytilenensis, which meet at a southwest-northeast borderline on the island of Lesbos (Heller et al., 2005).The distribution of P. pulcher is even more enigmatic (for P. lodosi see above).If allopatric speciation occurred (and a priori there are no reasons to invoke other theories) then it should have been isolated from P. sanctipauli for some time.But the ranges of P. pulcher and P. sanctipauli completely overlap.Both species live from sea level up to at least 1000 m, so it is not easy to imagine isolation occurring during cold periods.Isolation during a very warm interglacial seems also unlikely since P. sanctipauli occurs on islands without high mountains where it should have become extinct during warm periods.Further studies, especially of DNA sequences, may help elucidate the age and unusual evolutionary history of the three species P. sanctipauli, pulcher and lodosi.

TABLE 1 .
Morphological differences of the species of the Poecilimon sanctipauli group.