ASTRIN, Stüben & Astrin, 2010

Stüben, Peter E. & Astrin, Jonas J., 2010, Molecular phylogeny in endemic weevils: revision of the genera of Macaronesian Cryptorhynchinae (Coleoptera: Curculionidae), Zoological Journal of the Linnean Society 160 (1), pp. 40-87 : 75-77

ORIGOACALLES STÜBEN & ASTRIN SUBGEN. NOV.

( FIGS 19A–E , 35 )

Type species of the genus Acalles : Acalles camelus (Fabricius, 1792) – Germany (including type locality), Europe

Type species of the subgenus Origoacalles : Acalles globulipennis Wollaston (1854)

Wollaston, 1854, 1857, 1864, 1865; de Marseul, 1875; Lundblad, 1958; Behne, 2000; Stüben, 2000a, c, 2002b, 2008a; Stüben et al., 2003; Stüben & Germann, 2005; Germann & Stüben, 2006; Astrin & Stüben, 2008.

Compilation of the species of the subgenus

Origoacalles subgen. nov.

Acalles (Origoacalles) globulipennis Wollaston (1854) comb. nov. (formerly: Acalles s.s.) – Madeira (including type locality), Tenerife, Gran Canaria, Mainland Portugal

= Acalles pilula var. b seminulum Wollaston (1864) syn. Stüben 2000: 85 – Tenerife

Acalles (Origoacalles) pilula Wollaston (1864) comb. nov. (formerly: Acalles s.s.) – La Palma (including type locality), Tenerife (Teno), La Gomera, El Hierro

Description

Head: The big, flat, and almost circular eyes covering the entire flanks of the head are noticeable. The rostrum of the ♂ is reddish brown, slender, finely punctured, two-thirds as long as the pronotum, and densely covered with light scales almost reaching the antennal insertion, the rostrum of the ♀ is clearly longer reaching three-quarters of the pronotum length.

Pronotum: 0.95–1.05¥ as long as wide; widest behind the middle, outline in dorsal view regularly rounded to the fore and hind margin, only robust specimens show an indicated lateral constriction close to the fore margin. The dense and fine punctures separated by narrow ridges only. The almost circular scales are the same colour as the scales of the elytra. The prolongation of the light and narrow lateral fascia, which starts on the fore half of the elytra is continued and widened on the flanks of the pronotum. The disc of the pronotum is convex without mid groove or depression. The light scutellar spot of the elytra is continued on the middle of the base of pronotum. The elytra are considerably wider than the pronotum (up to two elytral intervals).

Elytra: Shortly oval, 1.10–1.20¥ as long as wide ( Fig. 19A ); widest shortly in front of the middle to immediately behind the base and therefore of quite variable outline (almost spherical, shortly oval, or inversely egg-shaped). The narrow stripes are situated almost on the same level as the much wider intervals and consist of extremely fine punctures. There are robust black tufts of bristles on the first and third interval of the elytral slope. Further black tufts of bristles are situated behind a spot of light (beige) scales on the anterior third of the elytra on the first (also indicated on the third) interval. The brown integument consists of circular, predominantly isolated scales.

Legs: Particularly tibia and tarsus (light) reddish brown. The front femur reaches the fore margin of the pronotum, the hind femur reaches the tip of the elytra. The slender, light scales are raised on the femur and stick out vertically on the outer edge of the tibia.

Venter: Metasternum between midcoxae as wide as midcoxae in diameter; sternites predominantly with long, slender bristles (depending on the degree of abrasion hair-like as well). The first sternite is – as in Echinodera – longer than the three following combined ( Fig. 35 ).

Aedeagus: Triangular, ending acute-angled; resembling the aedeagus of the Central European Acalles like A. misellus Boheman (1844) , A. fallax Boheman (1844) , and A. papei A. & F. Solari, 1905, etc. ( Stüben et al., 2003) – and is separated from this species by lacking the structure of the internal sac ( Fig. 19B ).

Differential diagnosis and discussion: According to the habitus, Acalles s.s. of the European mainland and Origoacalles are very similar (and their status as sister taxa is fully supported in the tree). The most conspicuous character of both taxa is the almost ‘globular’ to shortly oval outline of the elytra. The elytra are only 1.2¥ as long as high and decline almost perpendicularly in lateral view (cf. Fig. 19A ). In addition, according to the acuminately tapering apex of the aedeagus, both species of Origoacalles are comparable with the Acalles s.s. species of the western Palaearctic that also have such ‘triangular’ aedeagi (cf. Fig. 19B ). Amongst others this group includes Acalles sintraniensis Stüben, 1999 , Acalles papei A. & F. Solari, 1905, Acalles kippenbergi Dieckmann, 1982 , Acalles tibialis (Weise, 1891) , Acalles ptinoides (Marsham, 1802) , Acalles petryszaki Dieckmann, 1982 , Acalles echinatus (Germar, 1824) , Acalles fallax Boheman (1844) , Acalles misellus Boheman (1844) , and Acalles almeriaensis Stüben, 2001 . The mentioned combination of characters is absent in all other species of Macaronesian Cryptorhynchinae .

However, the species of Origoacalles also share two significant characters with the species of Echinodera : (1) the first abdominal sternite is clearly longer than the three following, very short sternites taken together (in Acalles s.s. maximally as long as the three following sternites combined); (2) as in Echinodera , the structure of the internal sac of aedeagus is lacking (this structure is always present in Acalles s.s. and in all other Macaronesian species) (cf. Figs 17B, 19B ). See also the ‘Key to the genera and subgenera of Macaronesian Cryptorhynchinae’.

Probably only studies on population genetics would reveal whether these Atlantic species could have colonized Madeira first (coming from the Iberian Peninsula) and spread afterwards (as opposed to the more ‘usual’ direction of colonization; Stüben, 2000c) – to the Canary Islands, with a further species, Acalles pilula , evolving on the western islands (cf. Fig. 19D ). The species of Origoacalles are specialized on decay- ing twigs of dead wood (cf. Fig. 19C ) and form an absolutely discrete group with no phylogenetic contact to any other Macaronesian Cryptorhynchinae .

Etymology: Origoacalles (origo, Latin: origin, provenance): the mitochondrial tree shows the species of Origoacalles as the sister group to Acalles s.s. and the genus shares some morphological characters with the genus Echinodera . The habitus of the Origoacalles species is consistent with that of the European species of Acalles s.s.

Distribution: Western Canary Islands, Madeira, Portugal.

Figures

Figure 35. Acalles globulipennis and Echinodera pallida: first abdominal sternite clearly longer than the three following (very narrow) segments combined (here vs. Madeiracalles albolineatus: first abdominal sternite maximally as long as the three following sternites combined (second sternite as long as or longer than sternite 3 and 4 combined).

Figures 2–22. Morphological, biological, and ecological comparison of the genera and subgenera of Macaronesian Cryptorhynchinae along with the respective sections of the tree; (TS) = type species. Figures 4E and 5E show a section of the tree that results when 16S sequences for Aeoniacalles aeonisimilis* and Dendroacalles euphorbiacus* are excluded.