Glaesoconnus, Jałoszyński, Paweł & Perkovsky, Evgeny, 2016

Jałoszyński, Paweł & Perkovsky, Evgeny, 2016, Diversity of Scydmaeninae (Coleoptera: Staphylinidae) in Upper Eocene Rovno amber, Zootaxa 4157 (1), pp. 1-85 : 33-34

† Glaesoconnus gen. n.

Type species: Glaesoconnus unicus (here designated).

Diagnosis. A genus of Glandulariini with antennae gradually thickened distally; basisternal part of prosternum about as long as coxal part and demarcated posteriorly by complete bisinuate carina; notosternal sutures complete; hypomeral ridges absent; prosternal intercoxal region lacking process or carina; mesoventrite lacking median carina; metaventral intercoxal process narrow and notched at middle; lateral margins of metacoxae distant from lateral margins of metaventrite; pronotum lacking lateral edges or carinae, with two pairs of antebasal pits; each elytron with one pair of small and asetose basal foveae; elytral setae ordered in longitudinal rows; head and prothorax lacking thick bristles.

Description. Body (103–107) elongate and moderately convex, with distinctly marked constriction between head and pronotum and between pronotum and elytra, BL about 1 mm.

Head capsule ( Figs 103, 105–107 ) with anterior part (in front of occipital constriction) subtrapezoidal and short, broader than long; eyes located posteriorly, large, strongly convex and coarsely faceted; tempora ( Fig 106 ; tm) distinct but shorter than eyes; occipital constriction ( Fig. 106 ; occ) about as broad as frons between eyes; frons ( Fig. 106 ; fr) subtrapezoidal, posteriorly confluent with strongly transverse vertex ( Fig. 106 ; vt). Gular plate ( Fig. 107 ; gp) subtrapezoidal, with sharply marked gular sutures ( Figs 107 ; gs).

Antennae ( Figs 103, 105–107 ) relatively short, gradually thickened distally and compact.

Pronotum ( Figs 103 , 106 ) in dorsal view round with weakly arcuate anterior and posterior margins and strongly rounded sides; anterior and posterior pronotal corners weakly marked, broadly obtuse-angled and blunt; pronotum broadest near middle; pronotal base with transverse row of four small and shallow antebasal pits ( Fig. 106 ; abp). Sides of pronotum lacking edges or carinae.

Prosternum with basisternal part ( Fig. 107 ; bst) long, as long or nearly as long as coxal part, posteriorly demarcated by sharply marked transverse and bisinuate anterior carina of procoxal cavities ( Fig. 107 ; acpc); notosternal sutures ( Fig. 107 ; nss) complete; interprocoxal region lacking carina or process; prothoracic hypomera ( Fig. 107 ; hy) lacking hypomeral ridges. Shape of inner (adcoxal) hypomeral margin, which is curved mesally behind procoxae, indicates that procoxal sockets are closed or narrowly open.

Mesoscutellum ( Fig. 106 ) well-visible between elytral bases, small, subtriangular.

Mesoventrite ( Fig. 107 ) lacking mesoventral intercoxal carina or process, but with large, broadly subtriangular median projection of anterior ridge ( Fig. 107 ; mpar) with its pointed tip located between anterior margins of procoxae.

Metaventrite ( Figs 107 ; v3) subrectangular, shorter than broad, with slightly rounded sides, posterior margin deeply bisinuate in front of metacoxae but weakly convex laterally, each metacoxa separated from lateral margin of metaventrite by nearly 1/4 width of ventrite ( Fig. 107 ); metaventral intercoxal process ( Fig. 107 ; mtvp) narrowly but distinctly separating metacoxae, with deep median notch. Anterior margin of metaventrite with dense 'wooly' setae forming bisinuate fringe behind posterior margins of mesocoxal cavities.

Elytra ( Figs 103–104 , 106 ) elongate and oval, each with two small but distinct and asetose basal elytral foveae ( Fig. 107 ; bef), humeral calli indistinct; elytral setae arranged in longitudinal rows ( Fig. 106 ).

Hind wings not visible.

Legs ( Figs 103, 105–107 ) moderately long, slender; pro- and mesocoxae suboval, metacoxae strongly transverse; all trochanters small and subtriangular; femora relatively strongly but gradually clavate; tibiae slender, straight or nearly straight; tarsi moderately long and slender, tarsomeres slightly flattened.

Abdomen ( Figs 105 , 107 ) with six visible sternites ( Fig. 107 ; st3–8) subequal in length except for slightly longer sternite VIII, suture between sternites VII and VIII distinct. Pygidium ( Figs 106–107 ; pg) partly exposed, subtriangular.

Distribution and composition. Glaesoconnus is represented by one nominal species from the Eocene of Europe ( Fig. 38 ), area currently within north-western Ukraine.

Etymology. The name Glaesoconnus is derived from the Latin glaesum (i.e., amber) and the stem - connus commonly used in generic names of Scydmaeninae . Gender masculine.

Remarks. There are only several extant genera of Glandulariini that have the lateral margins (or corners) of metacoxae distant from lateral margins of metaventrite, but none of them has this character as distinct as Glaesoconnus . These are: Neotropical Amimoscydmus Jałoszyński, 2013a ; West Palaearctic Leptocharis Reitter, 1887b ; Neotropical Parapseudoconnus Franz, 1980 (subgenus Neuraphomimus Franz, 1986b ); some species of Southern Hemisphere Sciacharis Brown, 1893 ; and Australian Scydmaenozila Jałoszyński, 2014a. Morphological structures of these taxa were illustrated in Jałoszyński (2013a, 2014a, c, 2015f). All these genera have a distinctly carinate and long mesoventral intercoxal process separating mesocoxae; Glaesoconnus has the intermesocoxal region lacking any carinate structure ( Fig. 107 ).

The genus most similar to Glaesoconnus is the Holarctic Stenichnus Thomson, 1859 , whose morphological structures were illustrated in detail in Jałoszyński (2013b). However, in Stenichnus (especially in the nominotypical subgenus), the mesoventral process is narrow, but still well-visible between mesocoxae. Glaesoconnus differs from Stenichnus not only in the intermesocoxal region, but also in the long basisternal part of prosternum (rudimentary, much shorter than half length of the coxal part of prosternum in Stenichnus ) and in having two distinct basal foveae on each elytron (one large fovea in Stenichnus ). Characters shared by Glaesoconnus and Stenichnus are: the gradually thickened antennae (however, in Glaesoconnus they are much more compact than in any species of Stenichnus ); the pronotum lacking lateral edges and bearing more than one pair of antebasal pits (but the shape of pronotum in dorsal view is strikingly different in these genera; Stenichnus having the pronotum broadest in the anterior third vs. near middle in Glaesoconnus ); the sharp and complete transverse carina demarcating the basisternal part of prosternum from procoxal cavities; the prothoracic hypomera lacking hypomeral ridges; the mesoventrite with large, subtriangular median projection of the anterior ridge; the dense and 'wooly' setae forming a fringe along posterior margins of the mesocoxal cavities; the narrow and deeply notched metaventral intercoxal process; and the mesoscutellum visible between elytral bases.

Figures

FIGURES 103 – 105. Holotype of Glaesoconnus unicus sp. n. (K- 5770). Habitus in dorsal (103), lateral (104) and ventral (105) views.

FIGURES 106 – 107. Holotype of Glaesoconnus unicus sp. n. (K- 5770). Habitus in dorsal (106) and ventral (107) views. Abbreviations: acps, anterior carina of procoxal cavities; abp, antebasal pit; bef, basal elytral fovea; bst, basisternal part of prosternum; fr, frons; gp, gular plate; gs, gular suture; hy, hypomeron; mn, mentum; mpar, median projection of anterior ridge; msvp, mesoventral intercoxal process; mtvp, metaventral intercoxal process; mxp 2 – 4, maxillary palpomere II – IV; nss, notosternal suture; occ, occipital constriction; pg, pygidium; psp, st 3 – 8, abdominal sternite III – VIII; tm, temple; v 3, metaventrite; vt, vertex.

FIGURES 35 – 38. Location of the Rovno Region (35 − 36) and the Klesov, Dubrovitsa and Vyrka amber mines (37) in the present-day Europe; location of the Rovno Region during Eocene (38).