Euconnus palaeogenus, 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 : 56-60

† Euconnus (incertae sedis) palaeogenus sp. n.

( Figs 25 , 171–181 )

Type material. Holotype: Late Eocene of Europe , Rovno amber: presumably male; inclusion in elongate, subtriangular or drop-shaped piece of amber 13 mm long ( Fig. 25 ), collection number K-6045 ( SIZK).

Diagnosis. Euconnus with four terminal antennomeres forming moderately well demarcated club; antennomere XI longer than IX–X, modified, with strongly concave mesal margin; BL 1.40 mm; EI 1.24.

Description. Body ( Figs 171–181 ) elongate, moderately slender and strongly convex, dark brown; BL 1.40 mm.

Head ( Figs 171–181 ) broadest at eyes, HL 0.25 mm, HW 0.33 mm; vertex ( Fig. 177 ; vt) inversely subtrapezoidal, strongly transverse; frons ( Fig. 177 ; fr) posteriorly confluent with vertex and subtrapezoidal, strongly transverse; supraantennal tubercles weakly raised but distinct; compound eyes large, strongly convex, oval; tempora ( Fig. 177 ; tm) in strictly dorsal ( Fig. 177 ) and lateral ( Fig. 181 ) view distinctly longer than eyes. Punctures on frons and vertex ( Fig. 176 ) fine, separated by spaces 3–5 × as wide as diameters of punctures; setae ( Fig. 176 ) sparse, short, suberect. Antennae ( Figs 171–181 ) about as long as half BL, AnL 0.73 mm, antennal club moderately distinctly demarcated, composed of antennomeres VIII–XI; antennomeres I–II strongly elongate, III– IV each about as long as broad, V indistinctly elongate, VI and VII indistinctly transverse, VIII–X strongly transverse, XI modified, with strongly concave mesal margin, slightly longer than IX–X combined, not broader than X and about twice as long as broad, with blunt apex.

Pronotum ( Figs 171–181 ) as long as broad, broadest near anterior fourth; PL 0.38 mm, PW 0.38 mm; anterior margin slightly concave; sides rounded in anterior half and slightly sinuate in posterior third; anterior pronotal corners weakly marked; posterior corners distinct, obtuse-angled; posterior margin shallowly bisinuate; base with distinct but short sublateral carinae ( Fig. 176 ; slc) and two pairs of antebasal pits ( Fig. 176 ; abp), of which inner pits are larger. Punctures on pronotal disc ( Fig. 176 ) small but distinct, separated by spaces 3–5 times as wide as diameters of punctures; setae ( Fig. 176 ) short, sparse, suberect; sides of pronotum with relatively dense thick bristles.

Elytra ( Figs 171–181 ) elongate oval, strongly convex, broadest site not possible to define, EL 0.78 mm, EW 0.63 mm, EI 1.24; punctures and setae similar to those on pronotum ( Fig. 176 ). Scutellum not visible between elytral bases.

Legs ( Figs 171–181 ) moderately long, slender, unmodified.

Etymology. The name palaeogenus refers to the geologic period.

Remarks. This species can be unambiguously placed in Euconnus on the basis of the carinate and elevated mesoventral intercoxal process ( Fig. 178 ; msvp); the short and very broad metaventral intercoxal process ( Fig. 178 ; mtvp), broadly separating metacoxae; the scutellum not exposed between elytral bases; and the general body form. Although only one basal elytral fovea can be seen ( Fig. 177 ; bef), the elytral base is poorly visible and the second fovea (there are two foveae in Euconnus ) may be obscured by a band of turbid amber running along the dorsal surface of the beetle ( Fig. 174 ).

The general body shape, the shape of the head and pronotum, partly also the antennal structure and the arrangement of antebasal pronotal pits and sublateral pronotal carinae in E. palaeogenus are very similar to characters known in the subgenus Cladoconnus Reitter, 1909 . Morphological structures of the latter have never been illustrated in detail, but a review of the type species of this subgenus will be presented in one of the next parts of the ' Euconnus complex' series of papers by the first author, and all important characters have already been studied by scanning electron microscopy. Conclusions presented here are based on these results. Only two major differences can be seen between Euconnus (Cladoconnus) motschulskii ( Sturm, 1838) , the type species of Cladoconnus , and E. palaeogenus : the vertex, tempora, genae and postgenae in the former (and all other extant species of Cladoconnus ) are densely covered with thick bristles (missing in the fossil); and the antennal club in E. motschulskii (and all other species of Cladoconnus ) has the antennomeres VIII and IX strongly modified, elongate and with concave mesal margins, antennomeres X and XI are unmodified, whereas in E. palaeogenus the antennomeres VIII–X are unmodified and short, and XI is strongly elongate with concave mesal margin. There are other subgenera of Euconnus or genera of Glandulariini apparently closely allied to Euconnus which are defined primarily on the basis of male antennal modifications, e.g., Neotropical Euconnus ( Androconnus Franz, 1986c ) or Afrotropical Oneila Peringuey, 1899 , but they clearly differ both from Cladoconnus and E. palaeogenus not only in which antennomeres are modified and how, but also in other characters.

The close similarity between E. palaeogenus and extant members of Cladoconnus is undisputed, but the hallmark of Cladoconnus , the elongate and mesally concave antennomeres VIII and IX, is not present in the extinct species. Therefore, it is not placed in any subgenus, but can be treated as close to Cladoconnus .

Characters usually hardly discernible in amber inclusions of Glandulariini but exposed in E. palaeogenus are the lateral foveae located on the mesothorax (ventrolateral foveae; Fig. 181 ; vlf) and between the meso- and metathorax (dorsolateral foveae; Fig. 181 ; dlf). Two pairs or one pair of lateral foveae have been found in some genera of Glandulariini , including the Afrotropical and Himalayan Afroeudesis Franz, 1963 , Neotropical Anthicimimus Franz, 1993 , cosmopolitan Euconnus s. str. ( Jałoszyński 2012b), cosmopolitan Euconnus ( Napochus Thomson, 1859 ), probably cosmopolitan Euconnus ( Tetramelus Motschulsky, 1870 ), Australian Leascydmus Jałoszyński, 2014a, Australian ' Magellanoconnus ' Franz, 1986d (identity unclear (Jałoszyński 2014e)), Neotropical Meridaphes Jałoszyński, 2015h , Neotropical Mexiconnus Jałoszyński, 2013c, Neotropical Mimoscydmus Franz, 1980 , Afrotropical Oreoeudesis, Neotropical Parapseudoconnus, Chinese Schuelkelia Jałoszyński, 2015f , Southern Hemisphere Sciacharis , Australian Sciacharoides Jałoszyński, 2014a, Australian Scydmaenozila, Australian Scydmepitoxis Jałoszyński, 2014f , Australian Spinosciacharis Jałoszyński, 2014a, and Seychellan Stenichnoteras Scott, 1922 . Even in dry-mounted specimens of extant species these foveae are difficult to notice and typically they can be clearly seen only in transparent mounts. It is noteworthy that two pairs of foveae are wellvisible in E. palaeogenus , in an arrangement typical of Euconnus ( Jałoszyński 2012b) .

Figures

FIGURES 21 – 34. Specimens of Rovno amber with inclusions of Scydmaeninae. K- 8972, Rovnoscydmus sp. specimen 8 (21); K- 3322, Rovnoscydmus sp. specimen 9 (22); K- 15548,? Rovnoscydmus sp. specimen 10 (23); K- 8971,? Rovnoscydmus sp. specimen 11 (24); K- 6045, Euconnus palaeogenus sp. n. (25); K- 9126, Euconnus sp. 1 (26); K- 24859,? Euconnus sp. 2 (27); K- 24302, Stenichnus proavus sp. n. (28); UA- 2216, Microscydmus sp. 1 (29); K- 6943,? Microscydmus sp. 2 (30); K- 3657 a,? Microscydmus sp. 3 (31); K- 6764,? Scydmoraphes sp. 1 (32); K- 6274, Glandulariini gen. & sp. indet. 1 (33); K- 7089, Glandulariini gen. & sp. indet. 2 (34).

FIGURES 171 – 175. Holotype of Euconnus palaeogenus sp. n. (K- 6045). Habitus in dorsolateral (171), ventrolateral (172), nearly dorsal (173), dorsal (174) and lateral (175) views.

FIGURES 176 – 179. Holotype of Euconnus palaeogenus sp. n. (K- 6045). Habitus in nearly dorsal (176), ventral (178) and dorsolateral (179) views, and head in dorsal view (177). Abbreviations: abp, antebasal pit; bef, basal elytral fovea; bst, basisternal part of prosternum; cl, clypeus; fr, frons; hy, hypomeron; hypomeral ridge; lbr, labrum; mcp, mesocoxal projection; md, mandible; msvp, mesoventral intercoxal process; mtvp, metaventral intercoxal process; mxp 3 – 4, maxillary palpomere III – IV; nr, ' neck' region; nss, notosternal suture; slc, sublateral carina; tm, temple; v 3, metaventrite; vt, vertex.

FIGURES 180 – 181. Holotype of Euconnus palaeogenus sp. n. (K- 6045). Left lateral (180) and right laterodorsal (181) views. Abbreviations: dlf, dorsolateral fovea; vlf, ventrolateral fovea.