Lycus Fabricius, 1787: 163

Kusy, Dominik, Motyka, Michal, Fusek, Lukas, Li, Yun, Bocek, Matej, Bilkova, Renata, Ruskova, Michaela & Bocak, Ladislav, 2021, Sexually dimorphic characters and shared aposematic patterns mislead the morphology-based classification of the Lycini (Coleoptera: Lycidae), Zoological Journal of the Linnean Society 191 (3), pp. 902-902 : 902-

publication ID	https://doi.org/ 10.1093/zoolinnean/zlaa055
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treatment provided by	Felipe
scientific name	Lycus Fabricius, 1787: 163
status

Treatment

Lycus Fabricius, 1787: 163 View in CoL View at ENA .

Type species: Pyrochroa palliata Fabricius, 1775 . = Acantholycus Bourgeois, 1883 , syn. nov.

Type species: Lycus praemorsus Dalman, 1817 . = Demosis Waterhouse 1879 , syn. nov.

Type species: Demosis peltatus Waterhouse, 1879 . = Hololycus Bourgeois, 1883 , syn. nov.

Type species: Lycus intermedius Bourgeois, 1884 . = Lopholycus Bourgeois, 1883 , syn. nov.

Type species: Lycus raffrai Bourgeois, 1877 . = Chlamydolycus Bourgeois, 1883 , syn. nov.

Type species: Lycus trabeatus Guérin-Méneville, 1835 . = Merolycus Bourgeois, 1883 , syn. nov.

Type species: Lycus rostratus Linnaeus, 1767 . = Concavolycu s Marie, 1968, syn. nov.

Type species: Lycus maublanci Pic, 1933 . = Alycus Rafinesque, 1815 (objective synonym).

Type species: Pyrochroa palliata Fabricius, 1775 .

Diagnosis

Lycus is highly variable in the shape of elytra (e.g. Figs 9–11 View Figure 9 View Figure 10 View Figure 11 ), and most shapes are unique in the whole family. Most Lycus have, unlike Haplolycus , a short, robust phallus ( Figs 9P View Figure 9 – AM, 10 T –AA). If the phallus is slender, then its apex is simple and without any cleft ( Fig. 11R–T View Figure 11 ).

Redescription

Adults: Body slender. Head rostrate. Rostrum short to moderately long. Pronotum widest at base, with rectangular to slightly projected posterior angles, variable in shape. Elytra exhibit sexual dimorphism in most species, eventually moderately dilated posteriorly, with four indistinct costae in each elytron ( Figs 9A–O View Figure 9 , 10A–S View Figure 10 , 11A–P View Figure 11 ). Male genitalia without thorns; phallus often with terminal processes ( Figs 9P View Figure 9 – AM, 10 T –AA, 11 R – T).

Morphological diversity of Lycus: There are several conspicuous types of elytra in Lycus that can be described in detail. The ‘ Acantholycus -type’ clade (Supporting Information, Fig. S1 View Figure 1 ) contains species with the widened male elytra and elevated costa 3, which is sometimes projected at humeri in a thorn ( Fig. 9E, I, J View Figure 9 ). The female elytra have a strong costa 3 but never any thorn, and their elytra are slender ( Fig. 9D, H, L View Figure 9 ). The males display another trait, which has not been identified in other Lycini : the apical part of the elytra is projected in a posterolateral thorn, which marks the obtusely ‘cut’ apex ( Fig. 9E, G View Figure 9 ). These elytra resemble the silhouette of resting moths, which commonly resemble Lycini and Calopterini (L. Bocak, field observation). We do not know whether the mimetic moths are palatable and how commonly they co-occur in the range of these species of Lycus . The Müllerian mimics should resemble each other, meaning that the unique shape of the Acantholycus -like elytron is a result of coevolution (either convergence or advergence, depending on the number of individuals and numerical dominance of co-mimics; Sherratt, 2008).

The ‘ Merolycus type’ is represented by Lycus sp. 51, with flat, leaf-shaped male elytra ( Fig. 10K–M View Figure 10 ) and inconspicuously modified female elytra ( Fig. 10N–Q View Figure 10 ).

The ‘ Chlamydolycus type’ is a clade of several closely related species that have extremely flat elytra with an apical process ( Fig. 9J, K View Figure 9 ). These species have weak but apparent irregular transverse costae in elytra, and these resemble the venation of small, yellowish leaves of some shrubs in African savannahs (L. Bocak, field observation in Ethiopia). Although they are potentially inconspicuous when sparsely distributed on leaves, these beetles aggregate on flowers and are clearly visible from a distance.

The ‘ Lycus type’ contains species with globular elytra ( Fig. 9C View Figure 9 ). As in other species, the females have much narrower elytra ( Fig. 9D View Figure 9 ).

The terminal ‘ Lopholycus -type’ clade contains variable species, some of them with posteriorly widened male elytra and some with a thorn in the middle of the costa ( Fig. 11A–F View Figure 11 ). A protective function can be expected if a thorn is short and sharp ( Fig. 11B View Figure 11 ), but long, curved and weakly sclerotized thorns in some species can hardly have such a function ( Figs 10R View Figure 10 , 11Q View Figure 11 ).

Distribution

Afrotropical region ( Fig. 5A View Figure 5 ).

Remarks

Most species can be assigned to subgenera described by earlier authors using external morphological characters and with the shape of male genitalia. For example, the males of Acantholycus have the humeral part of costa 3 projected in a thorn, which can be long and acute ( Fig. 9E, I, K View Figure 9 ) and simultaneously, the species with such modified costa have the phallus with two finger-like processes ( Fig. 9Z View Figure 9 – AI). We could delimit a subgenus with these characters if we did not find several related species which do not have either the thorn in the elytron or the widened apical part of the phallus or both these characters ( Fig. 9A–D, P–Y View Figure 9 ). We face a similar problem in the delimitation of other subgenera, and therefore, we prefer to discard all these subgenera from the formal classification. If subgenera were to be accepted in the current form, it would be necessary to merge unrelated, deeply rooted species in a polyphyletic subgenus that lacks the distinct characters of the members of terminal lineages.

Demosis peltatus Waterhouse, 1879 was described from Botswana, and its genitalia indicate the relationships with Lycus View in CoL . We propose that Demosis Waterhouse 1879 should be synonymized with Lycus Fabricius, 1801 View in CoL .