New genus and species of broad-nosed weevils from Baltic amber and notes on fossils of the subfamily Entiminae (Coleoptera, Curculionidae)

Abstract Arostropsis groehni gen. et sp. n. is described from Baltic amber and temporarily placed in the tribe Naupactini. It differs from all recent Naupactini genera with open corbels by very short and flattened scape, distinct lateral carina of the pronotum and elytra, and the rostrum distinctly narrower than the head capsule. The shape of head in the extinct genus is somewhat similar to that of the extant Naupactini genera with enclosed corbels (Platyomus Sahlberg, 1823 and Aptolemus Schoenherr, 1842), but differs in the slender body, open corbels, very short antennal scape and epifrons without a median sulcus (only a longitudinal depression is slightly visible). It is also similar to the Tanymecine genus Pandeleteius Schoenherr, 1834 in general appearance, but distinct by the straight anterior edge of the pronotum, lack of postocular spurs, lobes, and vibrissae, a slightly sloping elytral declivity, lateral ridges on the pronotum, subflattened antennal scape, elongate rostrum, and sparsely setose epistome. A new synonymy of the generic names Protonaupactus Zherikhin, 1971 and Sucinophyllobius Wanat & Borowiec, 1986, syn. n., is established. The Madagascan genus Corecaulus Fairmaire, 1903 is transferred from the tribe Naupactini to the Brachyderini because of its connate claws and the similarity in chaetotaxy of the epistomal area with African and Madagascar Brachyderini genera. A key to the identification of known Baltic amber genera of Entiminae is proposed. A checklist of the prepleistocene fossil Entiminae, based on V.V. Zherikhin’s data, with remarks and corrections, is presented.

Keywords new genus and species, new synonymy, fossil Entiminae, Naupactini, Baltic amber, key, checklist introduction Having examined the Baltic amber weevils from the collection of Mr. Carsten Gröhn, a new genus and species belonging to the subfamily Entiminae is described. However its tribal attribution was questioned because of the aberrant shape of the head capsule and inaccessibility of structures normally used for diagnostics (e.g. genitalia). In studying the various characters of Entiminae weevils, it became readily apparent that one of the most useful diagnostic features at the suprageneric level is the structure of the mandibular processes. They show some variability within Entiminae in general, but within certain tribes is usually rather stable. Besides, the mandibular process of fossils can be used, if available, as an additional character for identification of tribes.
In the course of the current study, mandibular processes of 35 extant genera in 17 tribes, including 6 genera of the tribe Naupactini Gistel, 1848, were examined (results of this comparison will be published in a forthcoming paper).
In addition, non-American genera treated in the Naupactini were also examined. As a result, the Madagascar genus Corecaulus Fairmaire, 1903 (type, female examined, MNHN) was transferred from the tribe Naupactini to Brachyderini, as its claws are connate in the basal third and similar to those in the genera Podionops Schoenherr, 1847 (South Africa) and Lagocaulus Fairmaire, 1903 (Madagascar) with the long median sulcus at the vertex and chaetotaxy of the epistomal area.
The type specimens of some poorly known taxa were re-examined. Phyllobius sobrinus Voss, 1972 was placed in the genus Sucinophyllobius (Wanat and Borovec 1986). A redescription of Protonaupactus is provided and a new taxonomic placement is proposed for this genus in accordance with the current knowledge of the Tertiary Entiminae fauna (Zherikhin 1971(Zherikhin , 1992and original data). This new information is included in the online catalogue (Ponomarenko et al. 2011).

historical review of fossil Entiminae
The earliest descriptions of fossils from the subfamily Entiminae Schoenherr, 1823 were published by Heer (1847), Germar (1849), and Giebel (1856) in their reviews of "Tertiary" insects. One of the preceding publications includes a brief note on unrecognizable "Naupactus" species (Serres 1829). These authors assigned fossil species to recent genera. The oldest species treated as Entiminae (Sitonites melanarius) was dated from the Upper Jurassic (Heer 1864), but this assignment with the broad-nosed weevils is rather doubtful and it is not considered reliable. The fossil specimens reliably identified as Entiminae originated from the Middle Eocene (Green River and Roan Mountain), the boundary between the Eocene and Oligocene, and also from the Lower Oligocene (Florissant and White River) (Scudder 1893). Exclusively rich American deposits with 47 genera and European deposits with 11 genera demonstrate the level of the Caenozoic diversity of this subfamily. The Middle Eocene deposits contain taxa resembling Entiminae but bear no mandibular processes, such as in Aterpini Lacordaire, 1866, usually assigned to the subfamily Cyclominae Schoenherr, 1826 . Some advanced genera of Entiminae have also been found with well developed postocular vibrissae and mandibles bearing mandibular processes, which are usually treated as members of the tribes Tanymecini Lacordaire, 1863 and Ophryastini Lacordaire, 1863. A rather large number of the taxa with free claws in the Caenozoic fossil weevils could be regarded as remarkable. Unfortunately, poor preservation of weevils from the Green River and most other American sediments make it difficult to determine generic or even tribal attributions, as most important characters (particularly legs and thin structures of the rostrum) seem to be rarely available for study. On the other hand, good preservation of some compression remnants makes it possible to provide precise systematic interpretations. In particular, the inprints of Geralophus fossicius Scudder, 1893 from Florissant, initially treated as Alophini LeConte, 1874, have the distinct transverse sulcus at the base of the epifrons, and the latter was transferred to Cylydrorhinini Lacordaire, 1863 or Aterpini (Cyclominae) (see Scudder 1893: plate II, Figs 16, 17 and 24); however, a more precise placement is scarcely possible due to the masking of fine structures of the mouthparts and epistomal area of the rostrum. Most Entiminae described from the Upper Eocene resin of Denmark, Poland and Russia (Voss 1953(Voss , 1972Zherikhin 1971;Wanat and Boroviec 1986) are in quite good condition.

Baltic amber Entiminae and their systematic and biographic links
The Baltic amber weevils apparently share more similarity with recent groups occurring mostly in the Indo-Malayan (Oriental) and Neotropical Regions (Zherikhin 1971). The biotic similarity could be due to the more homogeneous Paleogene Euro-Asian biota which now mostly remains in the recent "Himalayan-Burmanian-Yunannian block" (Takhtajan 1970;Kirejtshuk and Kurochkin 2010), but the link between this Paleogene biota with the recent Neotropical fauna is still unclear. Nevertheless, the Baltic amber fauna of Entiminae comprises two fossil genera, Paonaupactus Voss, 1953and Protonaupactus Zherikhin, 1971, linked to the Neotropics, versus Sucinophyllobius Wanat & Boroviec, 1986, linked to the Indo-Malayan Region. Polydrusus Germar, 1817, is the only confirmed recent genus known from Baltic amber. It was established by the paleoendemic, monotypic subgenus Palaeodrosus Zherikhin, 1971, and is highly diverse in the recent fauna of the warm-temperate zone of the Palaearctic where it comprises 204 species. Another recent Palaearctic genus recorded from Baltic amber may be Trachyphloeus Germar, 1824(Klebs 1910, but this data is still not confirmed. The genus Paonaupactus Voss, 1953 is monotypic and it is considered as a member of the tribe Anypotactini Champion, 1911 (Alonso-Zarazaga and. Protonaupactus Zherikhin, 1971 is also monotypic and it was originally placed in the tribe Naupactini Gistel, 1856). The genus Sucinophyllobius Wanat & Boroviec, 1986 was proposed for Phyllobius sobrinus Voss, 1972 and another species (Sucinophyllobius viridis Wanat & Boroviec, 1986) was also described in it. According to the recent catalogue of weevil genera (Alonso-Zarazaga and , Sucinophyllobius belongs to the tribe Cyphicerini Lacordaire, 1863. Preliminary study and a comparison of Sucinophylobius with Cyphicerus reveals that the characters of the head and prothorax make it questionable if Sucinophyllobius belongs within the subtribe Cyphicerina (see further discussion below under Protonaupactus).

Methods
The usual optic equipment was used for descriptions, including a Leica MZ 16.0 microscope provided with a CCD camera and camera lucida. Morphological terms mostly follow Thompson (1992), Emden (1944), and Doyen (1966). Special terms related to the rostrum structure follow Oberprieler 1988 and details of the epistomal area follow Morimoto et al. (2006).
Measurements. All measurements were taken with an ocular-micrometer. Body length was measured from the anterior margin of the eyes to the apex of the elytra, and rostrum length from the rostrum apex to the anterior margin of the eyes. Width of the rostrum is the maximum distance between the lateral edges of the pterygia.
Imaging. All outline illustrations were drawn using a camera-lucida and modified with a Wacom Graphire 4 Classic XL A5 tablet in Corel Draw (version 11.633) Corel®. Merging of layers was done with Helicon Focus (version 5.0) HeliconSoft®. Amber samples were photographed as under normal conditions as well as in sugar syrup to provide more suitable light refraction.
Abbreviations of depositories. GPIH Institute of Geology and Palaeontology and Museum (Geologo-Paläontologisches Institut u. Museum), University of Hamburg; MNHN National Museum of Natural History (Museum National d'Histoire Naturelle), Paris; ZMUC Zoological Museum (Zoologisk Museum), University of Copenhagen.
Diagnosis. 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. Material examined. 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.

Arostropsis groehni
Etymology. The epithet of the new species is formed from the name of Carsten Gröhn, collector of its holotype.
Description. 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.
Comparison with recent genera. 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.
Comparison with Baltic amber entimine genera. Since Arostropsis gen. n. has free claws, only two other fossil genera, Paonaupactus Voss, 1953 andProtonaupactus 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.

Systematic position
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.
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.
They share almost the same characters of the rostrum, with moderately defined Ushaped 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.

Systematic position of Protonaupactus
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)  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.
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.
co-author was supported by the Deutsche Forschungsgemeinschaft grant: KL 1162/4-1, AOBJ 554623. The second co-author was supported by the Program of the Presidium of the Russian Academy of Sciences 'Origin of Biosphere and Evolution of Geo-Biological Systems' and Russian Foundation of Basic Research (grant 09-04-00789-a). The second co-author have also a pleasant duty to express his recognition to the Muséum national d'Histoire naturelle for providing him a possibility to work in this museum according to the program of visiting professors. The authors' work with the collection of ZIN was supported by the Russian Ministry of Education and Science.  van Emden in Zeuner, 1931 N13, Boet Tribe Trachyphloeini Lacordaire, 1863 47 Trachyphloeus sp. (Klebs, 1910) Pg23, BalJ Tribe Eudiagogini LeConte, 1874 48 Promecops tumidirostris Poinar et Brown, 2011 N11, DomJ Tribe uncertain