Stenostoma melitense Cameron, 1907

Poloni, Riccardo, Bologna, Marco A. & Riccieri, Alessandra, 2024, One genus, four different stories: evolutionary history, bionomics and biogeography of the monotypic tribe Stenostomatini (Coleoptera: Oedemeridae), Zoological Journal of the Linnean Society 200 (3), pp. 705-719 : 715

Stenostoma melitense Cameron, 1907

( Figs 1C, H , 2E, F , 6C, D )

Stenostoma melitense Cameron, 1907: 226 .

Stenostoma melitense – Bologna, 1981: 213, figs 2, 11–18.

Stenostoma melitense – Bologna, 1995: 520, fig. 1.

Stenostoma melitense – Vazquez, 2002: 107, 178, fig. c.

Type locality: [ Malta] ‘Malta, Jniena’ (Cameron 1907) .

Type specimens: We did not examine the types, but some topotypic specimens from Malta.

Short description: For an extended description, see Cameron (1907) and Bologna (1981). Body length: 6.1–8.5 mm. Colour of the body blue or greenish. Head distinctly rostrate, twice as long as wide ( Fig. 1H ). Pronotum elongated, cylindrical, slightly prolonged towards the head ( Fig. 1H ). Sub-humeral elytral costa faint and hardly visible. Aedeagus short, significantly narrowed towards the apex, curved ventrally and with a blunt apex ( Fig. 2F ).

Distribution: Known from the Maltese Archipelago ( Malta, Gozo, Comino and St. Paul islands) in the Sicilian Channel, central Mediterranean, and also found recently in southern Sicily, at Punta Braccetto (Santa Croce Camerina, Ragusa province), in front of Gozo Island.

Bologna (1981) erroneously recorded this species from Pantelleria Island, but this datum was corrected by the same author ( Bologna 1995), who described the population from Pantelleria as a distinct species ( S. cossyrense ; see above). Erroneously recorded also from Sardinia and Corsica, and generically from Sicily (for a synthesis, see Bologna 1981).

Ecology: In the Maltese archipelago, where S. rostratum does not occur, S. melitense inhabits calcareous rocky ground with halophile shrubs ( Fig. 6D; D . Mifsud and L. Spagoni, personal observation). In the southern Sicilian locality (Punta Braccetto), which is characterized by both rocky calcareous and dune habitats, it is syntopic with S. rostratum , but with a clear niche differentiation, because the latter species inhabits the fore-dunes, whereas S. melitense is found at least in the stabilized dunes (‘Malcomietalia dune grasslands’) with bushes ( Fig. 6C ), close to rocky habitat with halophile shrubs. This is the only locality of syntopy between two species of Stenostoma . The short courtship and copulation, both with the male dorsal in position on the female, were observed on the host flowers in southern Sicily (M.A.B., pers. obs.). The species was found in Malta feeding on Ferula communis L ( Apiaceae ) (cited also as undetermined umbellifer), Cynara cardunculus L., Anthemis sp. (possibly maritima L.) ( Asteraceae ) ( Bologna 1981, 1984), and on Thymbra capitata L. (Cav.) ( Lamiaceae ) (Alamanni; D. Mifsud, pers. comm.). In southern Sicily, it was collected feeding only on Scolymus hispanicus L. ( Asteraceae ) (M.A.B., pers. obs.). The ascertained phenology is from the end of May to August (Cameron 1907, Cameron and Caruana Gatto 1907; new records and authors' observations; Supporting Information, Table S2).

Figures

Figure 1. Habitus and detail of head and pronotum of the species within the genus Stenostoma. A–E, habitus. A, Stenostoma cossyrense. B, Stenostoma lowei. C, Stenostoma melitense. D, Stenostoma rostratum rostratum. E, Stenostoma rostratum septentrionale. F–L, detail of head and pronotum. F, S. cossyrense. G, S. lowei. H, S. melitense. I, S. rostratum rostratum. L, S. rostratum septentrionale.

Figure 2. Genitalia of the species within the genus Stenostoma. A, B, Stenostoma cossyrense tegmen (A) and aedeagus (B). C, D, Stenostoma lowei tegmen (C) and aedeagus (D). E, F, Stenostoma melitense tegmen (E) and aedeagus (F). G, H, Stenostoma rostratum rostratum tegmen (G) and aedeagus (H). I–M, Stenostoma rostratum septentrionale tegmen (I) aedeagus (L) and aedeagus, variability (M).

Figure 6. Biotopes of the species within the genus Stenostoma. A, Pantelleria, Piano Ghirlanda (Stenostoma cossyrense). B, Madeira, Eira do Serrado, Madeira (Stenostoma lowei). C, Sicily, Punta Braccetto, stabilized dunes (Stenostoma melitense). D, Malta, Gozo Island (S. melitense). E, Sicily, Punta Braccetto, dunes (Stenostoma rostratum). F, Sardinia, Porto Ferro (S. rostratum, habitat and oviposition site with dead wood).