About the enigmatic Dichotrachelus valesiacus Stierlin, 1878 (Coleoptera, Curculionidae, Cyclominae)

Th e status of Dichotrachelus valesiacus Stierlin, 1878 is revised. Th e holotype was examined and the following synonymy is proposed: D. verrucosus (Kiesenwetter, 1852) = D. valesiacus Stierlin, 1878 syn. nov.


Introduction
In Switzerland, the European and North African genus Dichotrachelus Stierlin, 1853 is represented with nine taxa (seven species and two subspecies of D. sulcipennis Stierlin, 1853).Th ree additional species (D. muscorum tournieri Stierlin, 1878, D. valesiacus Stierlin, 1878and D. seminudus Tournier, 1879) are problematic, since they are known only in type specimens.One additional species is probably new to science, unfortunately only a single specimen is known till now.
With the present contribution I focus on Dichotrachelus valesiacus.Th e species was based on material from the Valesian Alps (pass of Grand St. Bernhard), but since the time of its description, it was never found again.Th erefore it was suggested that it may be restricted to a small refuge area (Osella 1970, Scherler 1995), similarly to many other Dichotrachelus-species, whose distribution area is often very small.However, the status of the species was not altered since the fi rst description and in the revision of the genus (Osella 1970) D. valesiacus was treated as a valid species.Th e only type specimen of D. valesiacus known, has never been thoroughly examined.Its study indicates that D. valesiacus is not a valid species, but a synonym of D. verrucosus.In the following note the holotype of D. valesiacus is depicted and the new synonymy is established.

Material and methods
Th e male genital structures were extracted and stored in a glycerine containing glass vial, pinned under the mounted specimen.Th e genital structures were photographed beneath glycerine with a 4-megapixel digital camera (JVC) under a stereomicroscope.Th e same camera was used for depicting the habitus and tarsi.Th e images were modifi ed with the program Auto-Montage (Synoptics) for best results in depth of sharpness and then reworked using Adobe Photoshop version 10.0.1 (Adobe Systems Incorporated).Th e body length was measured dorsally from the apex of the elytra to the front margin of the thorax.Th e following acronyms are used: DEI -Deutsches Entomologisches Institut, Müncheberg; NMBE -Natural History Museum, Bern.

Results and discussion
Material examined: 1 male with the following indications: "Val Entremont St. Bernhard D. valesiacus Stierl."(Fig. 1) From the Stierlin collection, deposited in the collection of the DEI.
Body length (c.r.e.): 2.9 mm, maximal width: 1.4 mm.Th e most conspicuous traits providing evidence for the synonymy are depicted.Remarks: Th e specimen is in a comparable good condition, the following parts of the body are missing: right hind tarsus, right middle tarsus (from the third tarsal segment on), left fore tarsus, claw segment.
Th e single male specimen of D. valesiacus is the only one present in the Stierlin collection.Th e specimen fi ts in every detail the description of Stierlin (1878: 416-417).Stierlin did not mention any typical exemplars in the fi rst description.Only later in his "Fauna coleopterorum helvetica", he mentioned in a footnote "Bei dem einzigen Exemplare, das ich kenne..." which shows that only a single specimen was known to him (Stierlin 1898: 271).According to articles 72.4.1.1 and 73.1.2 of ICZN (2000) this specifi es unambiguously the holotype by monotypy.Hence, the use of the recommendation 73F with the designation of a lectotype is not necessary.However, it should be mentioned that the only specimen of D. valesiacus was thought to be a female since the revision of the genus (Osella 1970).Th e examination of the type revealed that it is a male specimen belonging to D. verrucosus (Kiesenwetter, 1852), distributed in the eastern and central Pyrenean Mountains in France (Kiesenwetter 1852, Osella 1970) and Spain (Meregalli 1987).One male specimen of D. verrucosus with the following indications was used for comparison: "Pyrénées Or.Dichotrach.verrucosus" from the Rätzer collection (NMBE) (Figs 2b,3b,4b,d,5b).
As shown, the unraveled D. valesiacus is in fact D. verrucosus.Since D. verrucosus is exclusive to the eastern and central Pyrenean Mountains, the type of D. valesiacus was evidently wrongly labeled.Th is mistake confused Stierlin (1878) when he referred it to a new species, although D. verrucosus was included in his revision.
Th e Swiss weevil fauna has lost with the present established synonymy the only species named after the most popular region for zoologists, the Valais.