ADEMOSYNIDAE Ponomarenko, 1968

Yan, Evgeny V., Beutel, Rolf G. & Ponomarenko, Alexander G., 2017, Ademosynidae (Insecta: Coleoptera): A new concept for a coleopteran key taxon and its phylogenetic affinities to the extant suborders, Palaeontologia Electronica 5 (8), pp. 1-22 : 5

Family † ADEMOSYNIDAE Ponomarenko, 1968 Ademosynidae : Ponomarenko, 1968, p. 128

Type genus. Ademosyne Handlirsch, 1906 .

Type species. Ademosyne major Handlirsch, 1906 .

Genera included. Dolichosyne Ponomarenko, 1969 ; Gnathosyne Ponomarenko, 1969 ; Ademosyne Handlirsch, 1906 ; Cephalosyne Ponomarenko, 1969 , Sphaerosyne Ponomarenko, 1969 , Petrosyne Ponomarenko, 1969 .

Differential diagnosis. Differs from almost all extant and extinct groups of beetles by the pronotum without anterior angles and with a rounded anterior margin. Differs from Archostemata (except for Jurodidae ) and stemgroup Coleoptera (except for † Rhombocoleidae ) in elytra with punctate stria. Revised description. Small to medium sized, oval beetles. Body surface usually covered with very small dense punctures, without large rounded or pentagonal tubercles or scale-like setae.

Head prognathous, large, transverse, almost quadrangular; half as wide as pronotum, more than 0.3 of its length concealed by anterior pronotal projection; dorsal protuberances absent, and also ventral antennal grooves and constricted neck region. Mandibles long and massive, distinctly protruding forward, at least half as long as head capsule, weakly curved apically; mandibular denticles missing. Compound eyes medium sized to large, not protruding laterally; ocelli absent.

Pronotum more or less distinctly narrowing anteriad; pronotal disk strongly convex and rounded anteriorly; anterolateral angles absent; propleura usually exposed, narrow, strip-like, tapering anteriorly. Well-developed prosternal process separating procoxae usually reaches posterior procoxal margin or slightly beyond it, rarely only half as long as procoxae, often widening apically; procoxal cavities open posteriorly.

Elytra with 9-12 punctate striae, not or only slightly protruding beyond abdominal apex posteriorly.

Mesoventrite very short, with distinct longitudinal suture; mesoventral pit almost always well developed; transverse suture absent. Mesocoxae distinctly separated. Meso- and metaventrite closely adjacent; externally visible membranous articulatory area absent.

Metaventrite trapeziform, with longitudinal and transverse sutures, the latter in some cases partially obliterated. All trochantins externally visible but usually with a narrow exposed portion. Metacoxae laterally reaching beyond lateral margin of metaventrite; coxal plates absent, posterior coxal margin only slightly excavated. Legs cursorial, with five unmodified tarsomeres.

Remarks. The re-examination of ademosynid type material revealed that the propleura is quite narrow and tapers anteriorly (internalized in Petrosyne ). The presence of a mesoventral transverse suture was not confirmed for the family. These two characters differ from the original descriptions ( Ponomarenko, 1969).

For key to genera of † Ademosynidae see Table 2.