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 : 78-79

ARANEACALLES STÜBEN & ASTRIN SUBGEN. NOV.

Type species of the genus Onyxacalles : Acalles luigionii Solari, 1907 – Italy: Lazio (type locality), SW-Europe

Type species of the subgenus Araneacalles : Acalles verrucosus Wollaston, 1863

Wollaston, 1863, 1864, 1865; de Marseul, 1875; Uyttenboogaart, 1940; Uyttenboogaart & Zumpt, 1940; Roudier, 1954; Lindberg, 1958; Oromí, 1984; García, Ortega & Pérez Sánchez, 1993; Behne, 2000; Riede & Stüben, 2000; Stüben, 1999b, 2000c, f, 2002a, 2003c, 2007b, 2008a; Stüben & Wolf, 2001; Stüben et al., 2001; Germann & Stüben, 2004, 2006; Stüben & Germann, 2005; Astrin & Stüben, 2008.

Compilation of the species of the subgenus

Araneacalles subgen. nov.

Onyxacalles (Araneacalles) verrucosus ( Wollaston, 1863) comb. nov. (formerly: Onyxacalles s.s.) – Tenerife (including type locality), El Hierro

Onyxacalles (Araneacalles) neglectus ( Kulbe, 1999) comb. nov. (formerly: Onyxacalles s.s.) – La Gomera (including type locality), El Hierro

Onyxacalles (Araneacalles) ringeli ( Kulbe, 1999) comb. nov. (formerly: Onyxacalles s.s.) – La Palma

Description

Size: 3.1–5.5 mm

Head: The slender, reddish brown and fine dotted rostrum of the ♂ as long as the pronotum, the rostrum of ♀ longer than the pronotum.

Pronotum: 1.1–1.2¥ as wide as long, widest at the end of the basal quarter, at the side regularly rounded, only robust specimens show a slight lateral constriction in front of the fore margin; disk of pronotum – covered with black scales – without a hollow; however, with a small dent behind the scutellum and on each side with an accumulation of some upright bristles. Pronotum laterally with a large, white (sometimes with reddish brown) fascia, which silhouetted in high contrast against the dark, nearly black integument of the whole habitus ( Fig. 18A ).

Elytra: Short- and long-oval, 1.2–1.4¥ as long as wide, widest at the end of the basal quarter, at the side regularly rounded, apex acute-oval, egg-shaped rounded; on the first interval with six, on the third and fifth intervals with three tapered and black humps of bristles, the bristles on the fifth interval sometimes a little bit brighter; on the elytral slope with a short, distinctive white fascia on the sutural strip and the first interval ( Fig. 18A ). The whole integument consists of oval, dark brown and black scales; only behind the middle on the seventh interval (covered from the hind femur) and on the sixth interval in front of the elytral base with a small white spot.

Legs: Very long, arachnoid. The front femur reaches the insertions of the antennae (the middle of rostrum); femura annulated with white spots; the outer edge of tibia with bristles sticking out vertically (upright erinaceous).

Venter: Second abdominal sternite a little bit longer than sternite 3 and 4 combined; Metasternum between the mesocoxae as wide as mesocoxae in diameter.

Aedeagus: With a long and narrow hook-shaped apex, characteristic for the species of the genus Onyxacalles ( Fig. 18B ).

Discussion and differential diagnosis: This group of species occurring on the western Canary Islands has already been discussed in a revision of the genus Onyxacalles ( Stüben, 1999b) . In this work Kulbe (1999) separated Onyxacalles neglectus and Onyxacalles ringeli from Onyxacalles verrucosus Wollaston, 1863 .

According to our analysis, the three Canarian species of Onyxacalles represent the sister group of Onyxacalles s.s. of the European mainland. Regarding their habitus (cf. Fig. 18A ) and the distinctive hookshaped apex of the aedeagus (cf. Fig. 18B ), the Canarian species definitely belong to the genus Onyxacalles , as corroborated by the total support values of the Onyxacalles clade. Besides the characters already mentioned, the uncommonly long and slender (‘spidery’) legs and the very long rostrum (especially in comparison to the eastern European species of Onyxacalles ) justify establishing a separate subgenus. Araneacalles is distinguished from all other Macaronesian Cryptorhynchinae by the characters described here. See also the ‘Key to the genera and subgenera of Macaronesian Cryptorhynchinae’.

It took a long time to find the evolutionary link between the ‘Atlantic fraction’ of Onyxacalles and the south-westernmost species of this genus from the Alps and the Pyrenees. This gap was recently closed by new descriptions from the Iberian Peninsula and north-west Africa ( Stüben & Wolf, 2001; Stüben, 2002a, 2003c). Furthermore, the scattered populations of Onyxacalles depend on standing deadwood within intact patches of natural forest. Thus, Onyxacalles populations have become rare or are highly endangered.

Biology and ecology: The species of the Canarian subgenus Araneacalles have nocturnal habits and live in dense natural forest – just like Onyxacalles s.s. in Europe, North Africa, and Asia Minor. The three Canarian species depend on natural laurel forest and especially on deadwood, something that does not apply for most of the other Macaronesian Cryptorhynchinae that live in trees and shrubs (cf. Fig. 18C ). The species group is endemic to the western islands Tenerife, La Gomera, El Hierro, and La Palma. The rearing of this group turned out to be very difficult.

Etymology: The name Araneacalles refers to the uncommonly long, spidery legs of the three species of Onyxacalles which occur on the Canaries.

Distribution: Endemic to the four western Canary Islands.

Figures

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.