Bembidion alekseevi
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Ordo: Coleoptera
Familia: Carabidae
Genus: Bembidion
Name
Bembidion alekseevi Schmidt & Michalik, 2017 – Wikispecies link – Pensoft Profile
Holotype
Female in Baltic amber; size of amber piece approximately 14 × 12 × 4 mm (irregularly cut, Fig. 31), with collection label data “AWI 130”, in Vitalii I. Alekseev Collection, Kaliningrad. This amber piece was found in the surf zone of the Baltic Sea coast of the Sambian peninsula, in winter 2014-2015.
Preservation status
The amber piece is permeated by broad light-reflecting flow lines particularly at level of the Bembidion inclusion. The anterior portion of the ventral side of the beetle body is covered by milky coating. Thus, mouth parts, ventral side of prothorax, and some portions of the dorsal surface of the fossil cannot by investigated by light microscopy (Figs 29–30). The specimen is markedly shrunken with its exoskeleton which is disintegrated, shattered, and dissociated from the inclusion wall (Fig. 35). However, the negative imprint of the beetle body (= inclusion wall) could be recovered in detail using micro-CT (Figs 32–36). The left elytron is somewhat impressed behind the middle which is probably the result of the embedding of an immature and thus teneral specimen (Fig. 32). The hindwings are inflated caudal of the elytra (Fig. 30).
Syninclusions. Few dirt particles, numerous air bubbles.
Description. Body length: 3.9 mm.
Colour: Head and pronotum blackish brown with marked metallic lustre. Elytra middle brown with yellowish side margin (eighth and part of the seventh intervals), a small yellowish pre-apical spot between sixth and eighth interval at the beginning of the apical elytral third, and additionally with small yellowish spots in the third (4 spots) and fifth intervals (3 spots) as shown in Fig. 28. Microsculpture: Surfaces of head including labrum and pronotum with deeply engraved isodiametric sculpticells. Elytral intervals with very finely engraved, small and irregularly formed meshes which are not clearly visible below magnification of ×100.
Head: Moderately large and transverse; length 0.84 mm, width 0.91 mm. Mandibles moderately stout. Labrum with apical margin slightly concave, dorsally with three pairs of setae near apical margin. Clypeus with one pair of setae in normal position. Apical segment of maxillary palpus subulate, approx. 2/5 of length of penultimate segment; penultimate segment rather long and slender, moderately dilated anteriorly. Antennae moderately slender, with pedicellus almost two times longer than broad, and with four antennomeres extending beyond the pronotal base. Mentum and submentum distinct (shape and setation of medio-apical tooth could not be recovered); pits absent. Eyes large, hemispherical protruded; tempora very small, approx. 1/16 of eyes diameter. Disk slightly convex, smooth apart from the prominent microsculpture. Frontal furrows very shallow, very short, absent on disk. Supraorbital furrows very shallow, without punctures; two supraorbital setae present and in usual position for Bembidion. The pore of the anterior supraorbital seta is semicirculary surrounded by a prominent ridge on its internal side (Fig. 36). Prothorax: Pronotum rather small, length 0.77 mm, width 1.02 mm, transverse (width/length = 1.32), 1.1 times broader than head, subcordate, broadest in middle, with sides distinctly concave in posterior third. Laterobasal angles large, slightly obtuse, not protruded laterally. Basal margin 1.05 times broader than apical margin. Disk moderately convex, smooth apart from the prominent microsculpture. Anterior margin slightly convex in middle, lateroapical angles small and rounded, slightly protruded. Posterior margin not beaded, distinctly convex in middle and concave near laterobasal angles. Median longitudinal impression moderately deep in middle, absent near pronotal apex and base; anterior and posterior transverse impressions very shallow, smooth; laterobasal foveae large and rounded, moderately deep, smooth. Lateral gutter narrow and flat, faintly widened in middle, smooth. Laterobasal carina long and straight, approx. 1/3 of length of pronotum. Both lateral and laterobasal setae present, with the lateral seta located slightly before middle of pronotum. Surface structures on ventral side of the prothorax could not be imaged. Pterothorax: Elytra in lateral view moderately convex, slightly flattened on disc, in dorsal very slender ovate, length 2.34 mm, width 1.52 mm, length/width = 1.54, widest slightly behind the middle, distinctly wider than pronotum (width of elytra/width of pronotum = 1.49). Surface and lateral border glabrous and smooth apart from the primary elytral setation. Shoulders moderately broad, humeral margin rounded, sides with preapical sinuation indistinct. Presence or absence of crista clavicularis as well as subapical plica could not be imaged. Parascutellar stria long, parascutellar seta present. All striae complete, slightly impressed but markedly punctate, intervals flat or slightly convex; apical stria deeply impressed from the apical cross of 5th and 6th stria towards apex; recurrent stria lacking. Ninth interval very narrow in front, slightly broadened from beginning of apical third towards apex (the left elytron of the specimen is artificially flattened in anterior third and therefore, the external intervals appearing distinctly broader caudally than on the right elytron, see Figs 19, 31). Each elytron with two discal setae in third interval, with relevant pores distinctly separated from third stria. Preapical seta located in the deepened apical portion of the seventh stria; the fine apical seta located at apical margin. Subapical setae of umbilicate series could not be imaged; the humeral series consist of four setae, with distance between first and second setae slightly larger than between second and third setae, and with distance between third and fourth setae distinctly larger than between first and second setae; the fourth seta located slightly caudad of the level of the anterior discal seta; two apical setae of the umbilicate series situated anterior of the junction of the eighth stria and lateral gutter. Metepisternum markedly long, glabrous and smooth, with outer margin 2.3 times longer than anterior margin. The surface of the metasternal process could not be imaged. Hindwings fully developed. Abdomen: Abdominal sternites V–VI with one, VII with two (female) pairs of setae near apical margin; surfaces smooth, without hairs or micropunctures.
Legs: Moderately short, unmodified, femora moderately robust, protibiae straight and moderately dilated towards apex.
Female genitalia: Could not be recovered using micro-CT.
Derivatio nominis
The new species is dedicated to Vitalii I. Alekseev, Kaliningrad, for his important contributions to the systematics and biogeography of Cenozoic Coleoptera.
Relationships and recognition
This fossil Bembidion is considered to be a representative of the subgenus Eupetedromus Netolitzky, 1911 based on combination of the following characters: (i) micro-meshes on surface of head and pronotum deeply engraved and thus contrasting with the elytra which appearing polished when viewed by magnification below x80; (ii) penultimate segment of maxillary palpus rather slender; (iii) anterior supraorbital pore on internal side semicirculary surrounded by a prominent ridge; (iv) supraorbital furrows very shallow; (v) pronotal median longitudinal impression not deepened near base; (vi) pronotal posterior transverse impressions very shallow; (vii) elytral discal setiferous pores distinctly separated from third stria; (viii) distance between third and fourth setae of the umbilical humeral series much larger than between first and second and between second and third setae. Similar patterns of elytral chaetotaxy are also observed in other species groups of Bembidion, e.g., Emphanes Motschulsky, 1850, Notaphemphanes Netolitzky, 1920, Notaphocampa Netolitzky, 1914, Notaphus Dejean, 1821, Omotaphus Netolitzky, 1914, Talanes Motschulsky, 1864, Trepanedoris Netolitzky, 1918, Trepanes Motschulsky, 1864, and the Diplocampa complex sensu Maddison (2012)[1]. Species of the latter complex differ from this fossil and other species of Eupetedromus by presence of long and deep frontal and suborbital furrows. The same feature applies for species of the subgenera Emphanes, Notaphemphanes, Talanes, Trepanedoris, and Trepanes which additionally differ by much more convex discs of head and pronotum, weakly engraved microsculpture on head and pronotum and, in most cases, by stouter penultimate maxillary palpomeres and deeper median longitudinal and posterior transverse impressions of pronotum. Species of Notaphus are very similar to the fossil B. alekseevi sp. n. last but not least due to the characteristic colour patterns of the body. However, species of Notaphus lack the prominent ridge on internal side of the anterior supraorbital pore which is observed in B. alekseevi sp. n. Most species of Notaphocampa and Omotaphus differ strikingly by very different patterns of its elytral microsculpture; in the Ethiopian species B. scotti Netolitzky, 1931 the micro-meshes on the elytra are extremely fine engraved similar to what is observed in B. alekseevi sp. n. (see Bonavita et al. 2016[2]), however, in B. scotti the microsculpture on pronotal surface is likewise weak and thus very different from what is developed in B. alekseevi sp. n.
Remarks on biogeography and ecology
The subgenus Eupetedromus contains ten species which are distributed in the temperate and boreal zones of the Holarctic region (Marggi et al. 2003[3], Lorenz 2005[4], Bousquet 2012[5]). The occurrence of B. alekseevi sp. n. in the Baltic amber forest is therefore in accordance with the expected distribution of Eupetedromus group during the Early Cenozoic if one would accept presence of extra-tropical habitat conditions at least locally in the area of this forest. Based on comparative studies, Wolfe (1975)[6] found close relationships of the flora of the Eocene northern Europe to the modern flora of Indo-Malaya. This flora represents a mixture of tropical/subtropical and temperate elements with occurrences of the latter along slopes of the many high elevated areas of this region. Based on evidences from insect fossils, Ander (1942)[7], Schmidt and Faille (2015)[8], and Schmidt et al. (2016b)[9] suggested the presence of higher elevated areas in the Baltic amber forests which may represent suitable habitats for insects adapted to the temperate climate, e.g., Eupetedromus ground beetles.
Taxon Treatment
- Schmidt, J; Michalik, P; 2017: The ground beetle genus Bembidion Latreille in Baltic amber: Review of preserved specimens and first 3D reconstruction of endophallic structures using X-ray microscopy (Coleoptera, Carabidae, Bembidiini) ZooKeys, (662): 101-126. doi
Images
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![Figures 18–26. Aedeagal median lobes and endophallic structures of recent Bembidiina (18–25) and the fossil Bembidion bukejsi sp. n. (26), left lateral view. 18 Hoquedela k. kirschenhoferi Müller-Motzfeld, 1988 19 Bembidion (Phyla) tethys Netolitzky, 1926 20 B. (Plataphus) f. fellmanni Mannerheim, 1823 21 B. (Melomalus) altaicum Gebler, 1833 22 B. (Peryphophila) eurydice Andrewes, 1926 23 B. (Andrewesa) patris Schmidt, 2010 24 B. (Bracteon) lapponicum Zetterstedt, 1828 25 B. (Odontium) striatum Fabricius, 1792 26 B. (Eodontium) bukejsi subgen. n., sp. n. (Fig. 26a, volume rendering with highlighted structures, see also Fig. 14; Fig. 26b, schematic reconstruction of putative organization of endophallic structures). Scale bar: 2.2 mm. Abbreviations: bsc = brush sclerite; bsc-fd-av = apico-ventral prolongation of the brush sclerite; csc = central sclerite; csc-ll = left lobe of central sclerite; csc-rl = right lobe of central sclerite; df = dorsal field; dpl = dorsal plate; fl = flagellum of the central fold system; N = N-sclerite (Maddison 2012[1]); of = ostidial flag.](/wiki/File:Zookeys-662-e12124-g006.jpg)
Other References
- ↑ 1.0 1.1 Maddison D (2012) Phylogeny of Bembidion and related ground beetles (Coleoptera: Carabidae: Trechinae: Bembidiini: Bembidiina). Molecular Phylogenetics and Evolution, 63: 533–576. http://dx.doi.org/10.1016/j.ympev.2012.01.015
- ↑ Bonavita P, Toledano L, Maddison D, VignaTaglianti A (2016) Bembidiina of the Afrotropical region: Bembidion subgenus Omotaphus Netolitzky, 1914 (Coleoptera, Carabidae, Bembidiini). Entomologische Blätter und Coleoptera 112(1): 67–106.
- ↑ Marggi W, Huber C, Müller-Motzfeld G, Hartmann M (2003) Bembidiini: Bembidiina. In: Löbl I Smetana A (Eds) Catalogue of Palaearctic Coleoptera. Volume 1. Archostemata - Myxophaga - Adephaga. Apollo Books, Stenstrup, 241–273.
- ↑ Lorenz W (2005) Systematic list of extant ground beetles of the world. Second edition. Published by the author, Tutzing, 530 pp.
- ↑ Bousquet Y (2012) Catalogue of Geadephaga (Coleoptera, Adephaga) of America, north of Mexico. Zookeys 245: 1–1722. https://doi.org/10.3897/zookeys.245.3416
- ↑ Wolfe J (1975) Some aspects of the plant geography of the Northern Hemisphere during the Late Cretaceous and Tertiary. Annals of the Missouri Botanical Garden 62: 264–279. https://doi.org/10.2307/2395198
- ↑ Ander K (1942) Die Insektenfauna des Baltischen Bernsteins nebst damit verknüpften zoogeographischen Problemen. Lunds Universitets Arsskrift N.F. 2, 38(4): 1–83.
- ↑ Schmidt J, Faille A (2015) Confirmation of occurrence of Trechus Clairville, 1806 in the Baltic amber forests, with description of a flightless edaphic species, and remarks on Trechoides Motschulsky, 1856 (Coleoptera: Carabidae: Trechini). Zootaxa 4028(4): 539–550. https://doi.org/10.11646/zootaxa.4028.4.5
- ↑ Schmidt J, Belousov I, Michalik P (2016b) X-Ray microscopy reveals endophallic structures in a new species of the ground beetle genus Trechus Clairville, 1806 from Baltic amber (Coleoptera: Carabidae: Trechini). Zookeys 614: 113–127. https://doi.org/10.3897/zookeys.614.9283
