Acalles

Schütte, André & Stüben, Peter E., 2015, Molecular systematics and morphological identification of the cryptic species of the genus Acalles Schoenherr, 1825, with descriptions of new species (Coleoptera: Curculionidae: Cryptorhynchinae), Zootaxa 3915 (1), pp. 1-51 : 9-11

Acalles tree

The phylogenetic reconstruction of 37 Western Palaearctic Acalles species and subspecies based on a Bayesian analysis, in general confirm the systematic classification based on morphological characters ( Bahr & Stüben 2002). Due to a lack of material, eight species could not be included in the molecular analysis: A. gracilipes , A. granulicollis , A. petryszaki , A. setulipennis . The following four species from the Caucasus have never been collected by the ZFMK or Curculio Institute: A. caucasiscus , A. reitteri , A. milleri and A. lederi . From our point of view, the classification of these four species to Acalles s. str. is questionable.

The systematic position of Acalles pulchellus is not clear as well. Only a few specimens have been found so far and because of its specific habitus and distinct internal sac structure we include this species in the genus Kyklioacalles for the time being.

Acalles ganglbaueri— one of 'the rare black species'—is mainly distributed in Bulgaria with some localities in Romania. The appearance of A. ganglbaueri is similar to A. caucasicus , but lacks the tuberculate elytral flanks of A. caucasicus . Both might be related to A. camelus , however they may constitute a separate genus, but this cannot be determined at the present time without molecular data.

This circumstance certainly applies to A. edoughensis as well (fig. 1a, 1b). This species, which has been collected in Tunisia and Spain around Barcelona, does not belong to Acalles s. str. This has been published in a West-Palaearctic overview tree of Cryptorhynchinae species in Astrin & Stüben et al. (2012) (fig. 3).

The nowadays disjunct distribution of Coloracalles humerosus and the distant sister taxon A. edoughensis goes back to the well known land bridge between Sicily and the Iberian Peninsula and North Africa. This is why both species can be found in Algeria on Mt. Edough and in Spain around Barcelona. However, despite the remarkable pdistance of 12.2% of the CO1 gene, which would point to recognition of a separate genus, we think we have found similarities in the elytral marks and endophalli. To avoid another monotypic genus beside Montanacalles nevadaensis , we place Acalles edoughensis in the genus Coloracalles , but the three species Coloracalles edoughensis , C. humerosus and Montanacalles nevadaensis are genetically and morphologically not closely related (see Astrin & Stüben 2008).

Pseudodichromacalles xerampelinus also does not belong to Acalles s. str. After one-and-a-half decades of intensive searching for this species, it was finally rediscovered in the winter of 2012 within the laurel forest of Tenerife on the fern Woodwardia radicans ( Stüben & Schütte 2013b), 150 years after Wollaston described the species in 1864. At first it seemed impossible to give P. xerampelinus a definite position within the known genera of Cryptorhynchinae from the Canary Islands. After studying the holotype we initially chose the species Canariacalles alluaudi because of the similarity of the internal sac structure of the aedeagus ( Stüben 2000c, Stüben & Astrin 2010a: 69). Only the molecular data of CO1 gene made a preliminary assignment possible, namely that it is related to the Pseudodichromacalles species P. fernandezi (Roudier, 1954) . Pseudodichromacalles fernandezi is widespread on El Hierro, La Gomera and Tenerife. In comparison with P. xerampelinus it shows a much wider range of host plants and prefers the sparse and rocky slopes of the laurel forest ( Stüben & Astrin 2010a, fig. 9). Taking the elongate habitus and elevated elytral intervals 1 and 3 into account, P. xerampelinus seems to have some morphological similarities to P. fernandezi (fig. 2a). Although the molecular distances are large and sufficient to justifiy a separate genus (10.3%), it seems more appropriate for us to waive the description of a new monotypic genus and keep P. xerampelinus within Pseudodichromacalles at this point ( Stüben & Schütte 2013b).

Acalles gracilipes F. Solari, 1938 from Algeria (only a female holotype available so far) and A. petryszaki Dieckmann, 1982 certainly belong—using morphological aspects—to Acalles s. str. So far there has been no opportunity to retrieve tissue with sufficient quality for sequencing (only an old dry specimen of A. petryszaki was available for sequencing, but unsuccessful).

The placement of A. setulipennis Desbrochers, 1871 within Acalles s.str is highly questionable, since its aedeagus has an exceptional ring-like internal sac structure (digit 30: 'Key to the species of Acalles'). This character is more similar to the genus Kyklioacalles Stüben, 1999 .

The descriptions of Acalles vorsti sp. nov. of the Balearic island Mallorca and Acalles iblanensis sp. nov. of the Middle Atlas mountain range in Morocco are based on "morphological findings". However, we became aware of a new species from the Canary Island La Gomera— Acalles granulimaculosus sp. nov. —after the molecular analysis of species belonging to the subgenus Origoacalles. Herewith, Acalles granulimaculosus sp. nov. (type locality: La Gomera) is separated from Acalles pilula Wollaston, 1864 (type locality: La Palma). Although the p-distances of 11.3% to 12.8% (CO1, uncorrected) between these two species leave no room for doubt, there are only a few morphological characters to justify their separation (see Chapter 6, "Taxonomy"). So far this new endemic species is only known from the Canary Island La Gomera, while its sister species A. pilula has spread all over the Canaries.

Regarding the species complex A. parvulus / temperei , we refer to our last biogeographical, morphological and molecular studies from 2006: there exists either a hybrid zone, or more likely, that " Acalles parvulus and Acalles temperei constitute a single, geographically structured species" ( Stüben & Astrin 2006).

The further three species complexes are discussed in detail.