Ephippiger, Cruciger and Cunii), with Special Reference to the Mechanics of Copulation (Orthoptera, Tettigoniidae)
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Eos, t. LX, págs. 43-54 (1984). Taxonomy of the Ephippiger ephippiger complex (ephippiger, cruciger and cunii), with special reference to the mechanics of copulation (Orthoptera, Tettigoniidae) BY J. C. HARTLEY and A. C. WARNE. INTRODUCTION. Bush-crickets of the genus Ephippiger are large bulky flightless insects with a low mobility and consequently- although widely distributed over Southern Europe the populations are discontinuous and often quite isolated. They have an extended egg diapause which means that eggs may hatch 2 to 5 years after laying and thus generations may overlap. During the course of our work on the developmental biology of the Tettigoniidae it became necessary to question the identity of some of the Ephippiger species. In particular, the identity of the three species recog- nised in the standard taxonomic works (CHOPARD, 1952 HARZ, 1969), E. ephippi- ger, E. cruciger and E. cunii, could not always be resolved by the keys and des- criptions given. The matter is further complicated by HARZ (1966) who splits E. ephippiger into a number of subspecies but at the same time admits to the possibility of hybriclisation of E. cruciger with E. ephippiger and E. cunii and also with E. terres- tris. Hybridisation has also been suggested on the basis of song patterns (Bus- NEL, 1963). VOISIN (1979), however, considers that the three species, E. ephippi- ger, E. cruciger and E. cunii, are no more than races of an extremely variable species E. ephippiger. Since this paper was submitted Duum et al. (1983, Tijdschrift voor Entomologie 126, 91-108) have published an account suggesting that these species should be grouped as a superspecies, for reasons of mating compatability. NADIG (1980) extensively studying E. terrestris and E. bormansi has decided that these two should no longer be regarded as separate species, but as subspecies of a single polytypic species E. terrestris. It seems possible that a similar situation pertains in the E. ephippiger group. Since we have been able to successfully interbreed the insects of this group an evalutaion of the separation characters and reappraisal of their taxonomic status now seems appropriate. PRESENT TAXONOMIC POSITION AND DISTRIBUTION. This is modified from HARZ (1969) vvhere details of the synonomy may be found. Ephippiger ephippiger (FTEBIG, 1784). The wide ranging European species divided by HARZ (1966) and ADAMOVIi' (1973) into : 44 J. C. HARTLEY, A. C. WARNE E. e. ephippiger (FIEBIG, 1784). Eastern Europe ; Austria, Poland, Cze- choslovakia, and throughout the Balkans. E. e. vitium (SERVILLE, 1831). Western Europe ; France, Belgium, Rhi- neland. E. e. moralesagacinoi HARZ, 1966. Northern Spain. E. e. vicheti HARZ, 1966. Southern slopes of Austrian and Italian alps. Fig. 1.—Outline map showing sites in France and Spain where ephippigers were collected. 1-15 (0) - Ephippiger ephippiger forms, 16-19 (X) - hybrid cruciger forms, 20-22 (+) - standard cruciger forms, 23-32 (0) - cunii forms. TAXONOMY OF THE «EPHIPPIGER EPHIPPIGER» COMPLEX 45 E. e. mischtschenkoi HARZ, 1966. European USSR. E. e. harzi ADAMOVIé, 1973. Central Serbia. E. e. usi ADAMOVI, 1973. North east Serbia. Ephippiger cruciger (FIEBER, 1853), (E. bitterensis MARQUET, 1877). Mediterra- nean coastal plain of France. Ephippiger cunii BOLIVAR, 1877. Eastern Pyrenees. These three so called species appear to be mutually exclusive with no overlap of ranges. The characters used to separate them are given in table 1. TABLE 1. SYNOPTIC TABLE OF CHARACTERS USED FOR SEPARATION OF THE E. ephippiger COMPLEX, BASED ON CHOPARD (1956) AND HARZ (1969). PRONOTUM ABDOMEN SPECIES Posterior Texture Appearance Sulcus mark Tergite tergite colour edge band E. ephippiger strongly dull none green/green- broad and pale reticulate brown or not distinct E. cruciger weakly shiny dar k mark green-brown/ broad and pale reticul ate or cross dark-brown E. cunii smooth shiny none olive green/ very narrow chestnut or none brown With regard to the subspecies of E. ephippiger, HARZ (1966) separated them entirely on a geographical basis and supported this rather tentatively, with slight differences in mean dimensions and the form of the titillators, but admitted con- siderable variation. This was restated rather more categorically in HARZ (1969). The two subspecies described by ADAMOVI (1973) are E. e. harzi, described as smaller than E. e. ephippiger, dark brown to violet shaded body, with long slender straight titillators and a long straightish ovipositor, and E. e. usi as larger, yellow ochre or yellowish green body, with robust titillators bearing a pronounced inward projection at the base, and with a hroad curved ovipositor. MATERIALS. All the insects on which our observations are based were collected by us, as adults or final instar nymphs, from sites indicated in fig. 1., between 1968 and 1980, or were raised in the laboratory from these parents using techniques described elsewhere (HARTLEy and DEAN, 1976) 1. The insects from sites 1-15 all matched the E. ephippiger form with a 1-2 syllable chirp. So also did specimens observed 1 Importation and breeding these insects was permitted under MAFF licence PHF 77. 46 J. C. HARTLEY, A. C. WARNE but not collected in the SW comer of France and the Western Pyrenees. The principal difference between the Ephippiger from these localities was that the northern specimens were relatively small and mainly green whereas the southern examples were larger and more contrastingly marked. According to HARZ (1966) those from sites 8-10 should be E. e. moralesagacinoi and the others E. e. vitium. Sites 20-22 produced specimens that clearly answered the descriptions for E. cruciger, but with a 2 syllable chirp (further comments, HARTLEY and DEAN, 1976), while those from sites 23-30 were easily recognisable as E. cunii vvith a 4-5 syllable chirp. Specimens from sites 31, 32 were by far the largest, with features intermediate between cunii and cruciger but with a chirp of 4-5 syllables. The southern slopes of the Massif Central in Herault, sites 16-19, produced specimens difficult to categorise in that they were generally of the size and ap- pearance of cruciger but had pronotal features of ephippiger. Their song was variable with 2-3 syllables per chirp. A few specimens were collected in 1981 near Lago Maggiore on the southern side of the Alps in Italy. These were small with green unbanded abdomens and matched the description of E. e. vicheti. They also produced a 1-2 syllable chirp. Two specimens collected near Skopje, Yugoslavia, in 1982, which while matching the descriptions of E. e. ephippiger, were indistinguishable from the Italian insects. They also produced a 1-2 syllable chirp. EVALUATION OF THE MORPHOLOGICAL CHARACTERS USED IN THE TAXONOMY OF THE GROUP. In order to evaluate these characters it is perhaps helpful to first consider their function, since if they have a precise function they are less lik-ely to variation and therefore more likely to be reliable than otherwise. Most of the morphological characters given are associated with the genitalia and hence consideration of the mating process and the mechanics of copulation is necessary. As in many other Tettigoniidae the male calls the female by a proclamation song. Once within antennal contact, sound plays no further role, and male-female recognition is entirely by touch. When contact has been made a receptive female locates the male abdomen by her palps and positions herself over it with her head aboye the male pronotum. The female can be seen to nibble at the dorsal surface of the male, so there is probably a pheronione secretion involved ; sometimes in old males parts of the pronotum may be chewed away. As the female takes position over the male, the male starts to lunge with the cerci in the region of the female subgenital plate until the cercal spurs (fig. 2 sp) engage the sternal soc- kets (figs. 2, 3 s) on the eighth sternite of the female. When the female is securely held, the male genitalia are partially everted and the titillators inserted between the base of the ovipositor and the posterior flap of the subgenital plate. This flap is pulled down, by rachet action of the titillators, to produce an opening into which the adeagus is inserted. Spermatophore extrusion follows, the male releases his grip and moves away. The structures associated with the subgenital plate of the male play no part in copulation in these insects. Cerci: The male cerci are the only structures involved in clasping the female during copulation, with the strongly sclerotised spurs engaging the sclerotised sockets on the subgenital plate of the female. Although BOLIVAR (1887) referred to the use of cerci as claspers in Tettigonia, and BERENGUIER (1908) and GER- TAXONOMY OF THE «EPHIPPIGER EPHIPPIGER» COMPLEX 47 HARDT (1913) additionally referred to receiving pits or sockets on the female subgenital plate of a number of species, the importance of the female structures has not been emphasised in modern taxonomic works, possibly because they are often obscured by shrinkage in dried specimens. The critical aspects are the positon and angle of the sockets and the orientation and reach of the spurs. In all our examples of the E. ephippiger complex there were no differences in the relative positions of either spurs or sockets. TABLE 2. MALE CERCAL REACH IN MILLIMETRES. CERCUS INTERCERCAL TOTAL BASE-SPUR LENGTH DISTANCE REACH RANGE GROUP DESIGNATION mean s. d. no. mean s. d. mean (mean + 1 s. d.) E. ephippiger group ephippiger (France or Spain) ... 0.96 0.08 8 2.14 0.05 4.06 3.85 4.27 cruciger ... ... ... ... 1.00 0.04 6 2.56 0.14 4.55 4.33 4.77 cunii ... ... ... ... ... 1.10 0.17 6 2.30 0.22 4.50 3.94 5.06 all plus hybrids ..