Clavicornaltica, SCHERER, 1974

Damaška, Albert František, Konstantinov, Alexander & Fikáček, Martin, 2022, Multiple origins of moss-inhabiting flea beetles (Coleoptera: Chrysomelidae): molecular phylogeny, overview of genera and a new genus from Africa, Zoological Journal of the Linnean Society 196, pp. 647-676 : 660-661

CLAVICORNALTICA SCHERER, 1974

( FIG. 4 )

Type species: Clavicornaltica besucheti Scherer, 1974 .

Synonymy: No generic synonyms.

Phylogenetic position: In our analysis, Clavicornaltica has a long branch suggesting its rapid evolution, and making its phylogenetic placement difficult to reveal. Our analysis revealed Clavicornaltica as a member of the Aphthonine–Chabrine clade, with Neocrepidodera as the sister-clade, albeit with low support (P = 0.64). DamaŠka et al. (2020) revealed Clavicornaltica to form a moderately supported clade with Neocrepidodera and Orestia Chevrolat in Dejean, 1836.

Diversity and distribution: To date, 27 species of Clavicornaltica are described from various countries across South-East Asia. The genus is distributed from Nepal, India and Sri Lanka to the Solomon Islands, one known species lives in Australia and the northern boundary of the range is in Japan and China. Because the treatment of Clavicornaltica and the dissection of genitalia are extremely difficult, older authors used a wide species concept, treating the observed variation as unnamed forms. Modern studies based on genitalia morphology have shown that this approach is incorrect and the true diversity of Clavicornaltica is huge, probably reaching hundreds of undescribed species.

Revisions: The complete fauna of Clavicornaltica was reviewed by Medvedev (1996); a long-term study on the genus was also performed by Manfred Döberl, but its results were never published. Konstantinov & Duckett (2005) described new species and provided a key for species distributed in southern China and Vietnam, Suenaga & Yoshida (2016) summarized the known fauna of Japan and Taiwan with descriptions of more new species. Other studies on Clavicornaltica only describe single new species, without providing a wider comparison or updated identification keys.

Morphological characteristics: Clavicornaltica specimens, being the smallest among leaf beetles, are characterized by very small body size (0.7–1.5 mm). Body generally extremely compact, round, pronotum and elytra strongly convex in lateral view. Head hypognathous, triangular in frontal view, in some species with developed frontal callosities and frontal ridge. Antennae short; antennomeres 5–11 strongly widened, forming a distinct antennal club. The shape of the antennal club varies from relatively elongated, not welldefined one to strongly compact and rounded (the latter is present in most species). Pronotum strongly convex, legs short. Metatibiae extremely widened. Procoxal cavities open posteriorly. Mesoventrite completely invisible in ventral view, entirely covered by an elongated anterior metaventral process. First abdominal ventrite with an anterior process reaching the space between metacoxae with distinct ridge surrounded by deep punctures. Elytra strongly convex, usually covered with poorly visible punctures. Males of most species winged; females of all known species flightless and wingless. The morphology of both male and female genitalia is extremely diverse and seems to be one of the only morphological characteristics useful for species-level diagnostics. Aedeagus moderately sclerotized to nearly completely unsclerotized; in many species, basal opening of the aedeagus strongly elongated, forming up to a half of the aedeagus length. Aedeagi of many species strongly curved in lateral view or, on the other hand, strongly elongated, in extreme cases longer than abdomen stretching up to prothorax. The morphological diversity of spermatheca is also high; the shape of the pump and receptacle varies from a cylindrical pump with distinctly separated, short and slender receptacle, to bow-like spermatheca with receptacle and pump fused. Duct usually short, but strongly coiled in many species; on the other hand, the duct is extremely shortened and nearly not present in some species. Vaginal palpi usually long, slender and parallel.

Ecology: Little information is available about Clavicornaltica ecology. The beetles are usually collected by sifting, males are sometimes detected in flight-intercept traps or malaise traps. Konstantinov et al. (2013) mentions some species to be associated with mosses, which is the reason why we list the genus here. However, the majority of species are probably associated with decaying material and can be collected by sifting forest leaf-litter without mosses. Therefore, we treat the genus as leaf-litter-inhabiting in the phylogenetic study.

Remarks: The unique morphology of Clavicornaltica makes the genus clearly distinguishable from all other flea beetle genera distributed in the Old World. The only genus similar to Clavicornaltica is Kiskeya Konstantinov & Chamorro-Lacayo, 2006 distributed in the West Indies. However, the two genera can be distinguished by different shape and structure of antennae and the antennal club, as well as by the shape of the metaventrite ( Kiskeya does not have the metaventral process covering the mesoventrite in the space between the mesocoxae) and procoxal cavities (in Kiskeya , procoxal cavities are closed). Because of the morphological uniformity and strong morphological difference from other genera, no hypothesis on the relationships between Clavicornaltica and other flea beetle genera has been proposed to date.

Figures

Figure 4. Moss-inhabiting flea beetle genera distributed in Asia. A A, Paraminotella nigrita; B, Benedictus shivalayanicus; C, Paraminota lauribina; D, Ivalia korakundah; E, Cangshanaltica nigra; F, Baoshanaltica minuta; G, Phaelota viridipennis; H, Clavicornaltica dali.