Dichotrachelus augusti, F. SOLARI, 1946

Germann, Christoph, 2011, Review of the Dichotrachelus alpestris STIERLIN, 1878 species group with evidence for a species complex of D. augusti F. SOLARI, 1946, and D. sondereggeri sp. nov. from Switzerland (Coleoptera, Curculionidae), Contributions to Natural History 17, pp. 1-21 : 4-5

Remarks on Dichotrachelus augusti

The holotype of D. augusti with the following indications by Solari (1946: 10–11): " Patria: Piemonte ( Champoluc in Valle Aosta ); holotypus ♀." and "Un solo esemplare, raccolto da mio figlio Augusto in Val di Cunea, il 15.VII.1935, nel muschio cresciuto su di una roccia ." was not examined. In return a total of 19 specimens of D. augusti from various localities were examined ( Appendix 1), including an unjustified ♂ " allotype " ( Gr. St. Bernhard Süd 2200 m 24.6.1953 // Schweiz leg. G. Frey // Dichotrachelus valesiacus STIERL. det. F. Stöcklein 1953 [handwritten; wrong determination] // Museum Frey Tutzing // Dichotrachelus augusti SOLARI allotypus! ♂ det. G. Osella 1970 [partly handwritten]), which had been subsequently attributed by Osella (1970: 522) as type material to augusti , but is not part of it.

Within the examination of the material of D. augusti , I made an interesting discovery concerning the shape of its aedeagus. Based on the shape of the tip of the medianlobus, three preliminarily named forms I–III can be differentiated ( Figs 18, 19 & 28 ). Form I is likely to be the typical form, as these specimens are from around the type locality. Form III was discovered in material from Col de Balme (solely two male specimens are known, and only one specimen contains an aedeagus ( Fig. 19 ), whereas the other one is lost) at the border between Switzerland and France. Form II was discovered, during comparison of specimens from around the type locality (Champoluc) and from Great St Bernard / Val Ferret area . From this perspective, a record of D. augusti (a single female specimen) from the southern side of Valle d'Aosta ( Fig. 28 ) is a further promising trace that should be followed up in the future.

For all these reported observations, only further specimens of D. augusti , which is obviously a species complex, will help to clarify the significance of these different forms. Special caution is needed within Dichotrachelus concerning the aedeagus-shape. Just recently Germann & Baur (2010) reported on two different forms of the aedeagus of D. imhoffi STIERLIN, 1857 present within all investigated populations.

As D. augusti has been only very rarely collected, the examination of mosses at similar – cold and rocky – places illustrated for D. sondereggeri sp. nov. ( Figs 33–34 ) or also encountered during the finds of D. augusti at La Peule in Val Ferret (unpubl. observations) might be especially successful. A very recent excursion by M. Geiser in the summer of 2010 to Col de Balme collecting on drier and warmer grounds, exclusively yielded specimens of D. rudeni STIERLIN, 1853 .

Figures

Figs 17–26: Male and female genitalia. 17–20: Tip of aedeagus: 17) Dichotrachelus sondereggeri sp. nov. from Corn dal Solcun; 18, 19) forms II (Val Ferret), and III (Col de Balme) of D. augusti species complex; 20) D. alpestris from Anzeindaz. 21–23: Spiculum ventrale: 21) D. sondereggeri sp. nov. from Corn dal Solcun; 22) D. augusti form II from Val Ferret; 23) D. alpestris from Anzeindaz. 24–26: Spermatheca: 24) D. sondereggeri sp. nov. from Corn dal Solcun; 25) D. augusti form II from Val Ferret; 26) D. alpestris from Anzeindaz.

Fig. 28: Map providing a detailed view of the sites of the Dichotrachelus augusti species complex. White squares: D. augusti form I; white circles: D. augusti form II; black circle in white square: D. augusti form III. The respective shape of the apex of the aedeagus is pictured (I: Valle Aosta, Col Ran- zola; II: Val Ferret; III: Col de Balme); no data is available from the single record south of the Valle d'Aosta.

Figs 33–34. Biotope of Dichotrachelus sondereggeri sp. nov. on Corn dal Solcun (2480 m a.s.l.): 33) side peak in loose rocks providing a cold and humid microclimate where moss cushions with larvae were found; 34) detailed view of those moss cushions. Fotos: C. Germann.