Diochus electrus Chatzimanolis & Engel

Chatzimanolis, Stylianos & Engel, Michael S., 2011, A new species of Diochus from Baltic amber (Coleoptera, Staphylinidae, Diochini), ZooKeys 138, pp. 65-73 : 67-68

Diochus electrus Chatzimanolis & Engel sp. n. Figs 1-3

Holotype.

♀; KU-NHM-ENT, B-244 (Fig. 1); with labels: "Amber: Baltic, middle Eocene (Lutetian), blaue Erde, Northern Europe, KU-NHM-ENT-B244" // "HOLOTYPE Diochus electrus Chatzimanolis and Engel, des. Chatzimanolis and Engel 2011". Deposited in Fossil Insect Collection, Division of Entomology, University of Kansas Natural History Museum, Lawrence.

Diagnosis.

Diochus electrus can be distinguished from otherwestern Palearctic species of the genus by the differences in the relative proportion of elytra to pronotum (elytra longer than pronotum in Diochus electrus ; shorter than elytra in other species) and the proportions of the head (head much more elongate in the extant species than in Diochus electrus ).

Description.

Total length 3.5 mm; body coloration brown to black except antennae somewhat orange and abdominal segment VIII light brown. Head ovoid, length 0.56 mm, width 0.48 mm, slightly longer than wide (Fig. 2); compound eye length 0.18 mm, postoccular region convex, about twice as long as compound eyes; head with large macrosetae near posterior margin; head with transverse microsculpture and sparse small punctures. Antennomeres 1-5 longer than wide; antennomeres 6-10 subquadrate, antennomere 11 longer than wide; antennomere 1 as long as twice length of antennomere 2; antennomere 3 1.5 times longer than antennomere 2; antennomere 4 slightly shorter than antennomere 3; antennomere 5 slightly shorter than antennomere 4; antennomeres 6-9 subequal in length; antennomere 10 slightly longer than previous antennomeres but shorter than antennomere 11. Mouthparts not visible except right maxillary palp; maxillary palpomere I (P1) not visible, P2 longer than wide, club-like, about as long as P3; P3becoming wider distally; P4 extremely small, slender, conical, about seven times smaller than P3. Pronotum subquadrate, wider than head; pronotal length 0.64 mm, width 0.49 mm; anterolateral corners curved ventrally and not vis ible from above; pronotum smooth with sparsely scattered small, shallow punctures.Elytra longer than pronotum; elytra length 0.75 mm, elytra width 0.67 mm; elytra with dense macrosetae, expanding posteriorly; elytra sculptured as on pronotum. Legs (forelegs not visible) with slender tibiaecovered in long spurs distally; tarsi elongate, metatarsi almost as long as metatibia; metatarsomeres I and II greatly expanded. Abdomen with dense macrosetae (Figs 1, 3); segment VI longer than preceding segments; segment VII about twice as long as segment V; sternum VIII without any secondary sexual structures.

Etymology.

The specific epithet is an adjective derived from the Latin noun for amber (electrum).