Arostropsis groehni Yunakov & Kirejtshuk, sp. n.

The name of the new genus is formed from the Greek negative prefix “a”, “rōstron” (beak, bill, snout) and “opsis” (resembling a (specified) thing). Gender feminine.

Body elongate, in general appearance similar to Pandeleteius Schoenherr, 1834. Antenna with scape short, as long as pedicel (first funicular article; term after Doyen 1966) and 2^nd funicular article (antennomere 3) together, reaching anterior margin of eye, strongly widened and flattened dorso-ventrally along apical third. Rostrum distinctly elongate and slender, about half as thick as frons. Vertex with small frontal fossa anterior of eyes. Buccal cavity completely covered by prementum; transverse sulcus absent. Epistome sparsely setose: only two pairs of short (internal) and long (external) setae (such composition of setae is not found among groups of Naupactini and Anypotactini); parepistome (term after Morimoto et al. 2006) weakly acute and gently extending beyond contour of rostrum (Fig. 14). Antennal scrobes entirely lateral, just swinging fossa (term after Morimoto et al. 2006) slightly visible from above, pterygia scarcely pronounced. Mandibular process resembling that in other Naupactini (this structure was examined for six genera of Naupactini), weakly curved inward, with distinct dorsal carina, without inner basal tooth (Fig. 18). Eyes strongly asymmetrically convex. Pronotal and elytral disk distinctly depressed dorsally. Pronotum with distinct lateral ridges; its posterior edge bisinuate. Elytra subparallel-sided, with humeral and distinct subapical prominences, elytral declivity gently sloping. Femora obtuse, weakly swollen. Metatibiae with open corbels. Claws free.

Holotype “C 7968, GPIH 4516”, male (GPIH); the complete beetle with a clear integument is included in an irregular parallelepiped with the largest plane about 18.0 × 14.0 mm and the smallest one 11.0 × 7.0 mm; amber matter on right side from the beetle is rather homogeneous, but that from the left side of the inclusion consists of some layers, in which between the borders is a fine net of dark (almost blackish) organic matter.

The epithet of the new species is formed from the name of Carsten Gröhn, collector of its holotype.

Baltic Amber; Upper Eocene, Prussian Formation.

Baltic Sea coast and Amber quarry Jantarny near Kaliningrad (formerly Koenigsberg), Kaliningrad region, Russia.

Length 6.4, width 1.8, height 1.3 mm. Body slender, distinctly depressed from above. Pronotum and elytra strongly carinate at sides. Integument densely covered with small, apparently metallic, lanceolate (apparently green) scales at both sides of body and legs.

Head. Rostrum 1.5 times as long as wide, narrow, distinctly narrower than head capsule, laterally depressed. Pterygia weakly extending beyond lateral contour of rostrum. Epistomal area not depressed. Lateral edges of epifrons at middle convex, narrowed towards middle, then parallel-sided, without basal, transverse depression or sulcus. Median sulcus shallow, extending towards pit between eyes, not continuing towards vertex. Head capsule not constricted beyond eyes. Frons distinctly convex, almost twice as wide as epifrons at level of antennal insertions. Maximum width of head at posterior part of eyes. Scape comparatively short, about 1/4 as long as funicle, strongly expanded apically, somewhat compressed dorsoventrally, not extending beyond anterior third of eyes, directed obliquely downwards in folded state. Funicle slender; all segments elongate, funicular segment 1 about three times as long as wide, 2^nd about two times as long as wide, 3^rd about 1.5 times as long as wide; 4^th-5^th about two times as long as wide, segments 6-7 about 1.5 times as long as wide. Club spindle-shaped and comparatively thin, with distinctly separated segments, about as long as funicular segments 1-7 together. Mandibles entirely bare (without scales), moderately extended beyond buccal cavity. The only remaining left mandibular process knife-shaped, in apical third slightly curved inward, without internal prominences, about 1.5 times as long as protruding part of mandibles.

Pronotum elongate, almost parallel-sided, with anterior and posterior constrictions widely expressed, weakly and evenly convex at sides, with disc weakly convex transversely and anterior edge curving upward; posterior edge slightly bisinuate; posterior angles widely rounded and somewhat projecting posteriorly; anterior edge nearly straight.

Elytra elongate, about 4.5 times as long as wide, parallel-sided, humeral prominences distinct (Fig. 8, hp), basal edge of elytra biconvex opposite the posterior pronotal depressions. Elytral declivity gently sloping (Fig. 7).

Legs slender. Femora slender, elongate, obtuse, weakly swollen in apical third. Tibiae slender and elongate. Protibiae gently curved inwards in apical third; with anterior row of thin spines. Metatibiae subflattened and with inner edge sinuate at apical third. Corbels open (Figs 6, cb; 8), without additional row of spines. Tarsi slender, setaceous, pelma well-developed (term after Doyen 1966). Tarsomere 1 almost as long as tarsomeres 2–3 combined. Ultimate tarsomere extended beyond lobes of tarsomere 3 by length of last one. Claws free. Procoxae comparatively small, situated in middle of prothorax (Fig. 8).

The new genus differs from all recent genera of Naupactini with open corbels and procoxae not completely separated from the prosternum (Mesagroicus Schoenherr, 1840, Eurymetopus Schoenherr, 1840, Melanocyphus Jekel, 1875, Trichonaupactus Hustache, 1939 ) in the following characters: short and depressed scape, rostrum narrow, epistomal area weakly setose, epifrons with a weakly developed median depression and vertex with very small fossa, not continuing to occiput.

Since Arostropsis gen. n. has free claws, only two other fossil genera, Paonaupactus Voss, 1953 and Protonaupactus Zherikhin, 1971, share the same character state and can be compared with the new genus. Arostropsis gen. n. strongly differs from both Paonaupactus and Protonaupactus in the following characters given in the key below.

This new genus is undoubtedly a member of Entiminae due to the presence of mandibular processes. Due to structural characters: mandibular processes long, knife-shaped (ibt not developed) - claws free, vertex and epifrons combined in uniform structure without transverse sulcus before eyes, the new genus could be assigned to the tribes Naupactini or Geonemini Gistel, 1848. Emden separated these groups from other ‘brachyderoid’ tribes of Entiminae with free claws (Tanymecini and Anypotactini) by the following characters (Table 1).

The position of Arostropsis is tested following the table:

Presumption 1 (Geonemini). Arostropsis gen.n. lacks the key characters of Geonemini such as: evenly sloping lateral edges of epifrons, very narrow vertex and anterior position of procoxae. Consequently this genus cannot be assigned to this tribe..

Presumption 2 (Tanymecini). Arostropsis gen. n. could not be considered in the tribe Tanymecini, due to absence of postocular vibrissae at the prothorax. The amount of vibrissae varies from genus to genus within Tanymecini but at least a few vibrissae are present (some Pandeleteius). We do not know any case in which vibrissae are completely absent, so it is unlikely that Arostropsis belongs to Tanymecini.

Presumption 3 (Anypotactini). Due to absence of transverse sulcus between vertex and epifrons and U-shaped epistome in Arostropsis it is impossible to consider this genus within Anypotactini.

Presumption 4 (Naupactini). The strictly lateral position of the eyes, flattened epifrons and very broad vertex resembles that of Arostropsis within Naupactini, however, the shape of the rostrum is very different from that of any known member of this tribe. This transformation of rostrum probably resulted in reduction of the frontal fossa (Fig. 10) that is normally (in genera with broad rostrum) deep, long and continuing from the anterior portion of epifrons to the occiput. Such head shape together with the unusual slender body makes it difficult to recognize Arostropsis as a member of the tribe Naupactini.

Probable bionomy. The long legs and well developed tarsal pelma (term after Doyen 1966) of the new species suggests that this beetle was capable of running swiftly between leaves and, therefore, it was likely a canopy-dweller.

Protonaupactus microphthalmus Zherikhin, 1971

Protonaupactus microphthalmus Zherikhin, 1971, Protonaupactus viridis (Wanat & Boroviec, 1986), comb. n., Protonaupactus sobrinus (Voss, 1972), comb. n.

Holotype: ZMUC903847, male (ZMUC); the complete beetle is included in a nearly regular amber piece, parallelepiped, with facets 14.0, 10.0 and 5.0 mm; one thin layer with wavy, light organic matter, small gas bubbles and small cracks located beneath the beetle.

Baltic Amber; Upper Eocene, Prussian Formation.

Denmark “Bernschteinschluss, Versterhavet bei Thisted, 17.xii.1895, Madsen leg.”.

Length 4.5, width 1.75, and height 1.65 mm. Beetle densely covered with metallic, shining scales (apparently green).

Head. Rostrum 1.5 times as long as wide at level of pterygia. Epifrons subparallel-sided, at level of antennal insertions abruptly widened anteriorly, weakly convex longitudinally, separated from frons by a distinct depression indicating a transverse sulcus hidden by dense scales. Pterygia strongly extending beyond lateral contour of rostrum. Epistome well-defined by U-shaped keel. Epistomal setae grouped in dense bunches at anterior epistomal angles. Each bunch bearing at least 5 setae. Epistomal angles pronounced apically. Anterior edge of pterygia densely setose. Antennal furrows distinct only in their basal half and not continuing obliquely to underside of rostrum, their dorsal and ventral edges somewhat divergent posteriorly. Eyes dorso-lateral, round and evenly convex. Frons slightly convex, as wide as epifrons between antennal insertions. Frontal fossa not visible because masking by scales. Antennae long. Scape straight, evenly thickened apically, reaching anterior constriction of pronotum. Funicle thin: pedicel about 0.7 time as long as 2^nd funicular article; 2^nd article about 3.5 times as long as wide; 3^rd –7^th articles weakly oblong, about 1.5 times as long as wide. Club ovoid, about 2.3 times as long as wide, its 1^st article significantly different in shape from 7^th funicular article.

Pronotum transverse; evenly convex at sides and disc, strongly constricted anteriorly and posteriorly. Its base slightly bisinuate. Anterior edge of pronotum straight, without postocular lobes, spurs or vibrissae. Scutellum significantly pronounced, subquadrate.

Elytra subparallel, hardly widened in apical half, with pronounced humeral prominences. Epipleural edge weekly but distinctly S-shaped. Wings well-developed, beetle apparently capable of flying. Elytral declivity abruptly sloping. Anterior edge of anal ventrite (hypopygidium) emarginate (Fig. 30).

Legs thin. Femora obtuse, weakly swollen in middle part. Protibiae straight at external edge, not widened at external apical angle. Metatibiae spatulate apically (Fig. 33), with open corbel but without additional setal row. Setal comb of all tibiae weakly-developed. Tarsi with well-developed setaceous pelma (term after Doyen 1966). Tarsomere 1 about as long as tarsomeres 2 and 3 combined. Tarsomere 3 with well-developed lobes. Ultimate tarsomere by 0.7 extending beyond lobes of tarsomere 3. Claws free.

This species is distinguished from Protonaupactus microphthalmus and Protonaupactus viridis by the metatibiae being strongly spatulate apically. The re-examination of the holotype of Phyllobius sobrinus Voss, 1972 demonstrates the particular structure of the head, which is very similar to some genera of Anypotactini (mostly from tropical America) and Cyphicerini (mostly from Old World tropics, distinctly separated groups): epistome U-shaped, convex, weakly sinuate anteriorly, and claws free (Figs 27, 31). This species also shares a well-developed, transverse sulcus on the rostrum (Fig. 25, 26, 35–39) with other groups of Anypotactini.

The comparison of Sucinophyllobius sobrinus, Sucinophyllobius viridis and Protonaupactus microphthalmus shows they are closely related species of the same genus. They share almost the same characters of the rostrum, with moderately defined U-shaped epistome having apically pronounced angles, long and slender antennae with the scape extending behind the anterior margin of the pronotum, funicular article 1 about 0.7 × as long as article 2, and article 2 about 3.5 × as long as wide.

Anypotactini and Cyphicerini are the only tribes of Entiminae whose relationships with Protonaupactus still need to be tested. Both tribes contain genera with the following characters: (1) claws free, (2) epistome deeply sinuate, parepistome distinctly protruding and bearing dense bunches of long setae, (3) swinging fossae long, fully visible in dorsal view, (4) pterygia strongly extended beyond rostrum.

The tribe Cyphicerini consists of rather diverse genera which may be divided into two subgroups by the structure of the prothorax and underside of the head: (1) a prosternum subflattened with straight anterior edge; b pronotum with straight anterior edge; c rostrum and head united in a consolidated structure; d underside of rostrum densely covered with scales, its sculpture uniform; e rostrum directed forwards (Mylacorrhinina and Myllocerina) or (2) a prosternum with anterior edge sinuate; b pronotum with distinct postocular lobes; c head and rostrum distinctly separated by transverse constriction; d basal area of underside of rostrum with glabrous integument which has a bare stripe reaching the eyes; e rostrum directed downwards (Acanthotrachelina, Cyphicerina, and Phytoscaphina).

Anypotactini include a group of genera that share a character set characteristic of the subgroup I of Cyphicerini and distinct from this subgroup in the transverse sulcus on the rostrum. However, this tribe displays an enormous variety in rostrum shape, and also shows both dorsal and lateral positions of the antennal scape which is normally folded above the eyes, along the rostrum, or folded obliquely downwards in the scrobe if developed. Both the antennal scape and funicle are quite slender, hence the antennae resemble a brachyderoid rather than otiorhynchoid type, like in Cyphicerini.

Anypotactus Schoenherr 1840, Polydacrys Schoenherr, 1833 and other genera with short rostrum and large pterygia belong to Anypotactini subgroup 1, and Prepodellus Kirsch, 1867, Hyphantus Germar, 1824 and other genera with long rostrum with very small pterygia belong to Anypotactini subgroup 2.

Protonaupactus combines both character sets, Anypotactini and Cyphicerini. Nevertheless, it can be easily distinguished from Cyphicerini subgr. 2 in sharing the basic character set of Cyphicerini subgr. 1 and Anypotactini subgr. 1. From Cyphicerini subgr.1 Protonaupactus differs particularly in the transverse sulcus on the rostrum (Fig. 25, 26). The new data on this fossil genus show that the distinctness between these tribes is not very clear and needs a further investigation.