Canariacalles, 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 : 69-71

CANARIACALLES STÜBEN & ASTRIN GEN. NOV.

( FIGS 2A–E , 23A, 24B )

Type species: Acalles neptunus alluaudi Uyttenboogaart, 1940

Wollaston, 1864; Uyttenboogaart, 1940; Roudier, 1954; Lindberg, 1958; Bayer & Stüben, 2000; Riede & Stüben, 2000; Sprick & Stüben, 2000; Stüben, 2000a, b, c; Behne, 2000; Stüben et al., 2003; Stüben & Germann, 2005.

Compilation of the species of the genus

Canariacalles

Canariacalles alluaudi (Uyttenboogaart, 1940) comb. nov. (formerly: Acalles ) – Gran Canaria (incl. type locality), Tenerife

= Acalles haraldi Roudier, 1954 syn. Stüben, 2000: 32

Canariacalles lanzarotensis (Stüben, 2000) comb. nov. (formerly: Acalles ) – Lanzarote (incl. type locality)

? Canariacalles xerampelinus ( Wollaston, 1864) (formerly: Acalles ) – Tenerife: Agua García (incl. type locality) – incertae sedis

Description

Size: 3.4–7.0 mm

Head: Rostrum in both sexes shorter than pronotum; basal half of rostrum either sparsely covered with scales (♀) or rostrum with a dense cover of scales that sometimes exceeds the insertion of the antenna (♂). The rostrum of the ♂ is conspicuously more robust, darker brown, and has more dense punctures in the apical part. Eyes rhombic.

Pronotum: 1.02–1.12¥ as wide as long; widest directly behind the middle; behind the front margin of pronotum either with an abrupt constriction, which causes an angular outline or without such constriction, which causes a regularly rounded outline. The disc of pronotum is complanate. The basic cover consists of light brown to brown scales mixed with a few pale dark brown marks. Under the dense cover of scales the fine punctures is almost invisible.

Elytra: Wide, angular, and robust; 1.28–1.31¥ as long as wide; widest behind the steeply sloped shoulders at the end of the first fifth, outline towards apex almost parallel (or slightly narrowed) to the posterior end of the broad dark fascia. Apex oval rounded without constriction. Crown line of elytra in lateral view at the disc of elytra almost a straight line on the same level as the crest of pronotum and sloping steeply behind the broad posterior fascia. The punctured stripes consisting of pit-like punctures that are even on the flanks of elytra always narrower than the punctures of the complanate intervals. On the posterior part of the dark brown fascia that spans over the whole width of the elytra there is a conspicuous longitudinal knob on the second and fourth interval, also the scutellar stripe is slightly superelevated here. Eighth interval immediately behind the base with knob-like swelling covered with light scales. The dense basic cover consists of tiny brown scales that shade into a dark brown cover of scales on the longitudinal knobs as well as on the posterior fascia. On the intervals the tiny, light brown, scaly bristles are arranged in one or two lines and separated from each other by 4–10 ¥ bristle length. The base of elytra protruding half-moon-like towards the suture.

Legs: Short, the front femur reaching the eye, the hind femur ending far from the apex of elytra only slightly protruding from the posterior dark fascia. The light brown scaly bristles on the femur are inconspicuous and very short; tibia annulated with belts of black scales.

Venter: Second abdominal sternite longer than sternites 3 and 4 combined; first and second sternite covered with small, shortly oval to circular bristles. The interspace between midcoxae of metasternum very narrow and at most half as wide as midcoxae.

Aedeagus: The inverse v-shaped structure of the internal sac discontinued in the midsection ( Fig. 2B ). Differential diagnosis and discussion: The species of the new genus Canariacalles are distinguished from all other Macaronesian Cryptorhynchinae by the rhombic shape of the eyes ( Fig. 23 ), the extremely robust habitus ( Fig. 2A ), and the inverse v-shaped structure of the internal sac of the aedeagus, which is discontinued in the midsection ( Fig. 2B ).

There is only one further species presenting an almost identical structure of the internal sac: Acalles xerampelinus Wollaston (1864) ( Fig. 24A, B ). This is the only cryptorhynchine species that until today was impossible to recover from the laurel forest of Tenerife (type locality: Agua García). According to Wollaston (1864), this species has been collected only a few times in the mountains of Anaga and Teno. It is obviously not a xerothermophilic species of the coastal succulent belt, but it probably belongs to the herbaceous vegetation of the laurel forest of the Canaries (potentially being monophagous on a species of the carrot family, an Apiaceae ). Given the fact that Acalles xerampelinus has a conspicuously different habitus from the species of the new genus Canariacalles and that there is no alternative option of classification, we here declare it incertae sedis. See also the ‘Key to the genera and subgenera of Macaronesian Cryptorhynchinae’.

The common ancestor of the Dichromacalles and Canariacalles species very likely represents the ‘missing link’ between the Macaronesian (or at least Canarian) species and the mainland. The morphological similarity to species of Dichromacalles , as for, e.g. Dichromacalles dromedarius , has already been pointed out (see Stüben, 2000b: fig. 1) and is corroborated by our mitochondrial phylogeny ( Fig. 1A , cf. see also discussion of P. fernandezi ).

Biology and ecology: In the Teno Mountains of Tenerife, Canariacalles alluaudi predominantly develops – often associated with Dichromacalles dromedarius – in dead stalks of Foeniculum vulgare Mill. ( Stüben, 2000a: 32) . However, adults of Canariacalles alluaudi have also been observed feeding on the poisonous succulent Ceropegia dichotoma Haw. ( Fig. 2C ). Canariacalles alluaudi larvae have been successfully reared on stems of Ceropegia until the second instar ( Stüben & Germann, 2005: 68). However, the species of the new genus live mainly on species of the carrot family ( Apiaceae ). On Gran Canaria (Tenteniguada, 700 m) during summer (July), we observed numerous larvae, pupae, and imagines still in their cocoons at about 10–20 cm below soil surface, in the dead stems of the Apiaceae Ferula linkii Webb ( Stüben, 2000a: 32) . The larvae and pupae have been described by Bayer & Stüben, (2000). The stridulatory organ of this species motivated the study on the sonic defence of Cryptorhynchinae . Such a defence strategy is adopted by those taxa of the weevil subfamily that develop in woody plants forming a resonating body ( Riede & Stüben, 2000). The development of Canariacalles in the stalks or root necks of several species of the carrot family ( Apiaceae ) shows many similarities to Dichromacalles development that mainly takes place in species of the daisy family ( Asteraceae ) ( Stüben & Behne, 1998; Bahr, 2001).

Canariacalles alluaudi has not been reported from the eastern islands Fuerteventura and Lanzarote but on the latter the genus is represented by Canariacalles lanzarotensis , which we consider to be the sister species of Canariacalles alluaudi because of their morphological similarity (not sequenced).

Etymology: The name Canariacalles refers to the supposition that the common ancestor of the species of this genus, early ‘Canarian islanders’, and of the species of Dichromacalles s.s. of northern Africa and western Europe very likely represents the ‘missing link’ to the North African mainland. The succulicole way of life of these two groups allows the assumption that the colonization of the Canary Islands took its beginning in the arid succulent belt of the eastern islands.

Distribution: As yet only known from the eastern islands Lanzarote and Gran Canaria as well as the central western island Tenerife.

Figures

Figure 1. A, Bayesian 50% majority rule consensus for the two analysed mitochondrial genes. Numbers indicate nodal posterior probabilities. The scale shows the expected nucleotide substitutions per site. Abbreviations in parentheses denote subgenus (see text). Genus names in bold indicate new nomenclature. Circles mark colonization events (in black: invasive species). For many Macaronesian species, the respective host plants are depicted. The second page of the tree shows the taxa corresponding to the ‘Atlantic clade’. B, chronogram based on relaxed phylogenetic analysis of the two mitochondrial genes, using the uncorrelated lognormal model of substitution rate variation. Numbers next to the nodes indicate mean divergence times (in Myr), with 95% confidence intervals of divergence times depicted as bars at the corresponding nodes. N.B. Although the underlying topology is that delivered by MrBayes, BEAST does not allow polytomies, which it resolves arbitrarily.

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.

Figures 23–24. 23, Canariacalles with rhombic eyes (in lateral view) in comparison with Aeoniacalles. 24, endophallus of Acalles xerampelinus in comparison with Canariacalles alluaudi.