Synanthedon spuleri

Bąkowski, Marek, 2013, Morphology of preimaginal stages and taxonomical relationship of Synanthedon spuleri (Fuchs, 1908) (Lepidoptera: Sesiidae) with closely related species in Central Europe, Zootaxa 3666 (2), pp. 194-202 : 200-201

Relationship of Synanthedon spuleri with closely related species in Central Europe

Larva: In terms of the morphology of larvae S. spuleri appears most similar to S. cephiformis . Setae P2 on the larval head of both species are almost half as long as seta A2. In comparison to the other two species, as well as in the majority of Synanthedon species, it is distinctly shorter than half of the length of A2.

Furthermore, there is also a similarity to S. cephiformis in the average number of crochets on a single ventral proleg (24), while this number is distinctly lower in the remaining two species and for S. loranthi and S. tipuliformis it is 17 and 18, respectively. S. spuleri larvae can be distinguished from the other examined species by having a somewhat posterior AF2 to the level of frons apex, while in the other cases AF2 is at about the level of frons apex. The larva of S. spuleri , similarly to the larva of S. tipuliformis , has the L2 on A9 distinctly shorter than V1, while the other species have the L2 on A9 distinctly longer than V1. But only in S. spuleri is the L2 on A9 located between SD1 and L1, whereas in the other species and in the majority of the Synanthedon species L2 on A9 is distinctly closer to SD1 than L1 (Bɖkowski 2013).

Pupa: Pupae of all studied species have a very long proboscis, which almost reaches the end of metathoracic legs in S. cephiformis and S. loranthi and is somewhat shorter in S. tipuliformis and S. spuleri . The latter two species, however, differ in the shape of the head projection, which is excised and prolonged to two points at its relatively narrow end in the dorsal view in S. tipuliformis , whereas it is widely rounded, sometimes widely truncated at the end, or slightly concave, but without two points in S. spuleri . In S. cephiformis and S. loranthi the plate of the blade is large, heavily dark bordered and frequently slightly irregularly concave at the end in the dorsal view. Laštůvka (1983) indicated the variability of the shape of head projections of these species.

Imago: The feature that distinguishes the adults of all compared species is the coloration of the anal tuft, which can be more or less covered with yellow scales or it may be entirely black. The distinction on the basis of the presence or absence of a yellow spot on the metathorax is particularly problematic. The specimens of S. spuleri recorded in Poland have a distinctly yellow spot on the metathorax, which clearly distinguishes them from S. tipuliformis . The features of male and female genitalia are also not always clearly distinctive.

Molecular studies of the mitochondrial cytochrome oxidase I (COI) markers indicate clearly that S. spuleri is more closely related to S. cephiformis than to S. tipuliformis (Bɖkowski 2013) . According to the analysis the latter species is more related to S. cruciati Bettag & Bläsius 2002 and S. loranthi .

According to Priesner et al. (1986) a mixture of two chemical compounds E3, Z13-18: Ac and E2, Z13-18: Ac in the ratio 100:8 is recommended for attracting S. tipuliformis and in the ratio 1:1 for S. spuleri , but this last blend is not very efficient. On the other hand, males of S. loranthi flew into the traps containing a mixture of the two compounds Z3, Z3-18: Ac and Z3, Z3-18: OH in the ratio 100:30. Thus far no males of S. cephiformis have been attracted to the tested attractants.

Conclusion

A comparative analysis of the morphology of the preimaginal stages, especially of the larvae of the studied closely related species, similarly to their molecular analysis, indicates that S. spuleri is more closely related to S. cephiformis than S. tipuliformis . However, further research is needed in this respect, for instance on the morphology of larvae and pupae of other closely related species like S. cruciati and S. geranii Kallies 1997 . Equally important is further research on the sexual ethology of the studied species.

Acknowledgements

I would like to express my sincere thanks to Marek Hołowiński (Hańsk, Poland) and Željko Predovnik (Polzela, Slovenia) for donation of the larval material. I thank two reviewers, Jadranka Rota (Turku, Finland) and Zdenek Laštůvka (Brno, Czech Republic), for useful comments on a previous version of the manuscript.