Hylocharini, Jacquelin du Val, 1859

Muona, Jyrki & Teräväinen, Marianna, 2020, A Re-evaluation of the Eucnemidae larval characters (Coleoptera), Papéis Avulsos de Zoologia 60 (28), pp. 1-13 : 5-6

Hylocharini

( Figs. 3 A-D)

Head capsule wide, flattened (c84), divided into ventral and dorsal plates (c83), forming a semi-circular disk with lateral tooth-like projections, antennae located in deep pits between front tooth and first lateral tooth ( Figs. 3 A-D) as in all Eucnemidae except Perothopinae (c85), in contrast to all other discussed taxa. Labrum fused to head without trace as in all Eucnemidae except Phyllocerinae and Pseudomenini (c88). Number of antennomeres reduced as in all Eucnemidae except Phyllocerinae and Pseudomeninae , in contrast to Elateridae , Cerophytidae and Throscidae (86). Mandibles very small, either feebly movable or fused to head between mouth and front tooth ( Fig. 3 ). Maxillolabial complex completely fused with epicranium as in other Eucnemidae except Perothopinae , Pseudomeninae and Anischiinae , contrary to Cerophytidae and Throscidae (separate, but incapable of movement) and Elateridae (freely movable) (c100). Presternum mostly undefined, but proventrum usually with two pairs of sclerotizations, one longitudinal medially and one square close to front corners, similar to those of most Melasinae , Eucneminae and Macraulacinae . Legs present as single setae, often visible as dark spot only as in all Eucnemidae except Perothopinae , Phyllocerinae , Pseudomeninae , Anischiinae and all non-eucnemids discussed. Abdominal segments with microtrichial patches and areoles ( Muona & Teräväinen, 2008), segment IX rarely with minute urogomphi. Spiracles with closing apparatus as in other Eucnemidae , all Cerophytidae and Throscidae , in contrast to Elateridae .

Several Dirhagini exhibit extreme hypermetamorphosis from small triangulin-type larvae ( Dirrhagofarsus Fleutiaux )to ones with large exodont mandibles and finally a more “normal” looking larva ( Microrhagus Fabricius ). Others appear to have a less active, perhaps nearly sessile, development and resemble dipteran larvae ( Farsus du Val, Arrhipis Fleutiaux ). These unusual developmental types are found also in Nematodini ( Nematodes Dejean , Trigonopleurus Bonvouloir ) and Eucneminae ( Eucnemis Ahrens ) and the tendency towards different developemental solutions seems to be a feature uniting the three most specious subfamilies, Eucneminae , Macraulacinae and Melasinae .

Figures

Figure3.Eucnemidae,Melasinae,larvalheads,ventral.(A)Xylophiluscorticalis (Paykull); (B) Hylis cariniceps (Reitter); (C) Prodirrhagus; (D) Dirrhagofarsus ernae Otto, Muona & MvcClarin. a = antenna, bt = basal tooth, ft = front tooth,lt = lateral tooth,m= mandible.