Yunakovius, Borovec, 2010

Borovec, Roman, 2010, A taxonomic study of Eastern Palaearctic Omiini (Coleoptera: Curculionidae: Entiminae), Acta Entomologica Musei Nationalis Pragae 50 (2), pp. 577-594 : 578-581

Yunakovius gen. nov.

( Figs. 1‒7 , 23 )

Type species. Yunakovius orientalis sp. nov. by present designation.

Description. Body length (rostrum excluded): 2.68‒3.52 mm.

Body dark brown, antennae and legs reddish brown. Elytra with erect and adherent piliform setae; striae with one row of short setae. Pronotum and head with short piliform adherent setae, pronotal setae transversally directed to midline ( Fig. 23 ).

Rostrum very short and wide, regularly tapering anteriad, with slightly concave sides. Epifrons significantly tapered posteriad, with slightly concave sides. Epistome not differentiated, frons not separated from epifrons. Scrobes in dorsal view completely visible in anterior half of rostrum, in lateral view very short, not reaching eye, strikingly enlarged posteriad, dorsal border subparallel with dorsal border of rostrum, directed above eye, ventral border directed towards ventral border of eye. Eyes small, strongly convex, distinctly protruding from outline of head, in lateral view placed in the middle of the head. Head and rostrum at the same level, epifrons in lateral view strongly vaulted ( Figs. 1–2 ).

Antenna with short scape, reaching anterior border of pronotum, slightly curved in the middle, shorter than funicle. Antennomeres 1 and 2 markedly longer than antennomeres 3–7.

Pronotum narrow, with regularly arcuated sides ( Fig. 3 ). Dorsal surface regularly vaulted, with double punctation, without any other structure ( Fig. 23 ).

Procoxal cavities contiguous, semiglobular, proximal to the anterior border of the pronotum, rather then nearer.

Scutellum very small, triangular.

Elytra oblong, with regularly arcuated sides, widest at midlength ( Fig. 3 ). Striae wide, punctate, placed in the same level as intervals, narrower than flat intervals ( Fig. 23 ).

Mesocoxa semiglobular, mesosternal process narrow. Metacoxae transverse, metasternal process very wide, obtuse, wider than transversal diameter of metacoxa.

Femora edentate. Outer margin of protibia straight, inner margin of protibia sinuate, apex subtruncate with dense fringe of fine, short, yellow setae and one distinct tooth at internal angle. Meso- and metatibia armed with one short spine at internal angle. Metatibial corbels opened. Metatarsus more slender than protarsus. Tarsomere 3 of all tarsi deeply bilobed, wider than the others. Ultimate tarsomere strikingly longer than previous one, claws fused at basal half.

Abdominal ventrite I as long as ventrite II and about as long as ventrites III and IV combined. Suture 1 (between abdominal ventrites I and II) sinuose and fine, sutures II–IV straight, wide and deep ( Fig. 4 ). Ventrites shiny, scarcely and finely punctate, with scarce, piliform, fine, semiadherent setae.

Male unknown.

Female genitalia. Apodeme of sternum VIII long, about three times as long as plate, apically contiguous inside of plate. Plate feebly sclerotised, narrow, without margo basalis and with indistinct margo apicalis, with apical setae ( Fig. 7 ). Ovipositor feebly sclerotised, long and slender, tapered apically, with long subapical, laterally protruding setae at apex of very short styli, almost invisible ( Fig. 6 ). Spermatheca C-shaped, with separated nodulus and ramus ( Fig. 5 ).

Etymology. This new genus is dedicated, with great pleasure, to my friend Nikolai Yunakov from the Zoological Institute in St. Petersburg, a prominent specialist in short-nosed weevils. Gender masculine.

Included taxa. The genus is described as monotypic.

Differential diagnosis. The newly described genus belongs to the tribe Omiini based on the dorsally placed scrobes, fully visible in dorsal view, epifrons in basal part distinctly narrower than the space between the anterior borders of eyes, elytra without developed humeri and claws fused in basal half. In the tribe Omiini , Yunakovius gen. nov. is similar to the genus Asphalmus Sharp, 1896 mainly in regards to the genital structures. Female genitalia of both genera are different from the remaining genera of the Omiini known from the western part of the Palaearctic Region in having the female sternum VIII apically terminated inside of a plate which lacks a margo basalis. The remaining genera of the Omiini from the western part of the Palaearctic Region have female sternum VIII with an apodeme creating a distinct margo basalis, not terminated inside the plate. While Asphalmus , is in the form of the rostrum, similar to Rhinomias Reitter, 1894 known from the Balkan peninsula and southern and central Europe, the form of the rostum of the newly described genus Yunakovius gen. nov. resembles that of the genus Baromiamima Borovec, 2006 known from the central and southern Europe. Based on available biological notes from locality labels, Yunakovius gen. nov. and Asphalmus inhabit similar ecological niche as Rhinomias and Baromiamima , i.e. they are living in plant debris and wood litter. Both genera are easily distinguishable according to the following characters, assumed as generic in the Omiini :

Asphalmus: Rostrum clearly separated from remaining part of the head by a wide and shallow transverse depression ( Fig. 9 ). Femora of all legs dentate. Rostrum with strongly concave sides and laterally protruding scrobes, creating pterygia ( Figs. 8 , 14, 20 ). The entire elytral striae depressed, striae wider than the width of one interval in basal part of elytra. Elytra with semiadherent short setae. Sexually reproducing species.

Yunakovius gen. nov.: Rostrum at the same level as the rest of the head, not separated by a transverse depression ( Fig. 2 ). Femora of all legs edentate. Rostrum with slightly concave sides and slightly protruding scrobes, not conspicuous in dorsal view ( Fig. 1 ). Only the punctures of elytral striae depressed, striae narrower than width of one interval in basal part of the elytra. Elytra with raised long setae. Parthenogenetic species.

The new genus Yunakovius gen. nov. can be included to the latest key to the genera of the tribe Omiini ( BOROVEC 2006) , by modifying the couplet 10, as follows:

10. Eyes very small, in lateral view, placed just in the middle between the dorsal and ventral border of the head. Vertical diameter of the eye in lateral view subequal to width of the apex of the antennal scape. Body rusty or dark brownish, elongate oval. .............. 10a

– Eyes large, in lateral view placed very near to the dorsal border of the head. Vertical diameter of the eye in lateral view distinctly larger than the width of the apex of the antennal scape. Body blackish, globose, oval or elongate oval. ................................ 11

10a. Body very small, shorter than 2.0 mm. Eyes inconspicuous in dorsal view. Ventral border of the antennal scrobe directed below the eye in lateral view. Hemisternite of the ovipositor without stylus, with scattered apical setae. Female sternum 8 with small oval plate, the apodeme not terminated inside the plate. .... Nanomias Yunakov, 2003

– Body larger, greater than 2.7 mm long. Eyes strongly prominent in dorsal view. Ventral border of the antennal scrobe directed towards ventral border of the eye. Hemisternite of the ovipositor with very short stylus armed with a brush of long setae placed on its apex. Female sternum 8 large, umbrella-shaped, apodeme terminated inside the plate. .................................................................................................... Yunakovius gen. nov.

Aside from the main diagnostic character (small eyes placed in the middle of the head in lateral view), Yunakovius gen. nov. can be distinguished from all other similar genera by following set of characters:

Baromiamima : Eyes flat in dorsal view, not prominent from the outline of the head. Elytra with long, erect setae in elytral striae. Spermatheca U-shaped, without differentiated nodulus and ramus. Hemisternite with long apical stylus. Female sternum 8 with small, oval plate and well distinguished margo basalis.

Yunakovius gen. nov.: Eyes significantly protruding from the outline of the head in dorsal view. Elytral striae with very short, adherent setae. Spermatheca C-shaped, with developed nodulus and ramus. Hemisternite with very short subapical stylus. Female sternum 8 with large, umbrella-shaped plate without margo basalis.

Euplatinus Desbrochers, 1907 : Sides of the rostrum very strongly concave in dorsal view. Hemisternite of the ovipositor without styli, with irregularly scattered setae at apical portion. Female sternum 8 with conspicuously developed margo basalis.

Yunakovius gen. nov.: Sides of the rostrum very feebly concave in dorsal view. Hemisternite of the ovipositor with short subapical styli with a brush of long setae at apex. Female sternum 8 without margo basalis.

Omiamima Silfverberg, 1977 : Rostrum with strongly concave sides in dorsal view. Interocular space less than 1.5 times larger than the space between the antennal insertions. Epifrons at midlength of the rostrum 0.5 times as wide as the rostrum. Hemisternite of the ovipositor short, without stylus. Female sternum 8 small, oval, with indistinct margo basalis.

Yunakovius gen. nov.: Rostrum with feebly concave sides in dorsal view. Interocular space almost two times larger than the space between antennal insertions. Epifrons at midlength of the rostrum 0.33 times as wide as the rostrum. Hemisternite of the ovipositor long, with short subapical stylus. Female sternum 8 large, umbrella-shaped, without margo basalis.

Omias Germar, 1817 : Body and femora black. Elytra mostly globose to short-oval. Hemisternite of the ovipositor without stylus. Female sternum 8 in females with a small plate and apodeme not terminated inside the plate.

Yunakovius gen. nov.: Body and femora dark brown. Elytra elongate oval. Hemisternite of the ovipositor with a short subapical stylus. Female sternum 8 with a large plate and the apodeme terminated just inside the plate.

By the combination of the epifrons narrower than the space between eyes and fused tarsal claws, Yunakovius gen. nov. could be placed also in the tribe Phyllobiini . PESARINI (1979) defined the tribe Phyllobiini by four characters, from which only the first two characters are included in all the species of the tribe: (1) tarsal claws fused; (2) metacoxae very near to each other, metasternal process narrow, arrow-shaped; (3) shoulders angularly prominent at elytral base; and (4) elytral vestiture contains scales of different shape, often with metallic sheen. Some species of Phyllobius Germar, 1824 , e.g. P. roseipennis Pesarini, 1973 , or species in the genera Oarius Desbrochers, 1905 and Argoptochus Weise, 1883 lack shoulders and therefore resemble Yunakovius gen. nov. Some species of Phyllobius also have elytra without scales as in Yunakovius gen. nov. But Yunakovius gen. nov. has widely separated metacoxae and the metasternal process is very wide and obtuse. The same character is also found in the genus Asphalmus . An additional character for distinguishing Yunakovius from the Phyllobiini is the position of the eyes: eyes are small; in lateral view, placed just in the middle of the head in Yunakovius gen. nov., whereas they are large, placed just in upper part of the head in all genera of the Phyllobiini . The difference in the position of the eyes is most likely related to the different lifestyles: Yunakovius gen. nov. is terricolous, has cryptic life habits and may be collected by sifting, whereas all Phyllobiini taxa are arboricolous or herbivorous and may be easily collected by beating trees and shrubs or by sweeping of plants. The lifestyle menti- oned above for Yunakovius gen. nov. is also shared by other omiine genera, e.g. Asphalmus , Rhinomias , Urometopus Formánek, 1904 , Baromiamima and others.

Figures

Figs. 1–13. 1–7 – Yunakovius orientalis gen. & sp. nov., holotype. 1 – head and rostrum, dorsal view; 2 – head and rostrum, lateral view (scale = 0.50 mm); 3 – pronotum and elytra in female, dorsal view (scale = 1.00 mm); 4 – abdominal ventrites (scale = 1.00 mm); 5 – spermatheca (scale = 0.25 mm); 6 – ovipositor (scale = 0.25 mm); 7 – sternum 8 in female (scale = 0.50 mm). 8–13 – Asphalmus japonicus Sharp, 1896, Japan. 8 – head and rostrum, dorsal view; 9 – head and rostrum, lateral view (scale = 0.50 mm); 10 – pronotum and elytra in male, dorsal view; 11 – pronotum and elytra in female, dorsal view (scale = 1.00 mm); 12 – abdominal ventrites (scale = 1.00 mm); 13 – aedeagus, ventral and lateral view (scale = 0.25 mm).

Figs. 23–26. Habitus. 23 – Yunakovius orientalis gen. & sp. nov. (paratype ♀, 3.1 mm, ZIN); 24 – Asphalmus japonicus Sharp, 1896 (♂, 3.8 mm, BMNH); 25 – A. ovatus (Sharp, 1896) (♂, 3.4 mm, BMNH); 26 – A. sharpi sp. nov. (holotype ♂, 3.0 mm, BMNH).

Figs. 14–22. 14–19 – Asphalmus ovatus (Sharp, 1896), Japan. 14 – head and rostrum, dorsal view (scale = 0.50 mm); 15 – pronotum and elytra in male, dorsal view; 16 – pronotum and elytra in female, dorsal view (scale = 1.00 mm); 17 – aedeagus, ventral and lateral view (scale = 0.25 mm); 18 – ovipositor (scale = 0.25 mm); 19 – sternum 8 in female (scale = 0.50 mm). 20-22 – A. sharpi sp. nov., holotype. 20 – head and rostrum, dorsal view (scale = 0.50 mm); 21 – pronotum and elytra in male, dorsal view (scale = 1.00 mm); 22 – aedeagus, ventral and lateral view. (scale = 0.25 mm).