Stachygethes Audisio & Cline, 2009

Audisio, Paolo, Cline, Andrew Richard, Biase, Alessio De, Antonini, Gloria, Mancini, Emiliano, Trizzino, Marco, Costantini, Lorenzo, Strika, Sirio, Lamanna, Francesco & Cerretti, Pierfilippo, 2009, Preliminary re-examination of genus-level taxonomy of the pollen beetle subfamily Meligethinae (Coleoptera: Nitidulidae), Acta Entomologica Musei Nationalis Pragae 49 (2), pp. 341-504 : 412-415

20. Stachygethes Audisio & Cline , gen. nov.

( Figs. 20 a–k )

Type species. Nitidula ruficornis Marsham, 1802: 131 (= Meligethes ruficornis ( Marsham, 1802) (by present designation) [= Stachygethes ruficornis ( Marsham, 1802) comb. nov.].

Generic description and diagnosis. Inclusive species vary greatly in size (1.5–3.8 mm length), and share the following combination of characters.

Body color and pubescence: pubescence silvery-whitish, variably developed, recumbent, never obscuring the blackish or dark brown and usually shining dorsal body surface; pronotal and elytral sides narrowly flattened, typically the same color as disc. Lateral margin of pronotum and elytra with a series of faintly distinct, small and short setae, each seta 0.3–0.5× as long as those on elytral disc; posterior margin of pronotum with long, usually distally bifid or trifid microsetae, microsetae uniformly distributed on middle region anterior to scutellum ( Fig. 20e ).

Dorsal habitus: body more or less convex, variably shaped, usually moderately slender and oval ( Figs. 20a, b ); dorsal punctures on discal portion of pronotum as large as or larger than eye facets, usually deeply impressed and densely distributed; anterior margin of clypeus truncate, and distinctly narrowly bordered ( Fig. 20c ), without small, faintly distinct, medial bulge; circum-ocular furrows (occipital sulci) on dorsal side of head narrow, moderately impressed, and anteriorly developed ( Fig. 20c ); eyes large and usually moderately projecting laterally ( Figs. 20a, b, c ); pronotum with obtusely distinct or almost completely rounded posterior angles, never directed posteriorly ( Figs. 20a, b ); scutellum regularly punctured on posterior half of exposed portion ( Fig. 20e ); elytra never transversely strigose, punctation simple, occasionally with faint traces of orange peel-like rugosity; elytral humeral angle moderately distinct, not protruding laterally ( Figs. 20a, b ); elytral humeral striae faint; elytral pre-sutural striae distinct, originating posteriorly to scutellar vertex, terminating close to elytral apex, delimiting on each elytron a flat and narrow sutural border, narrower than proximal portion of 3 rd antennomere; elytral apices truncately rounded in both sexes ( Fig. 20a ); pygidium partially exposed, moderately convex, apically rounded in both sexes ( Figs. 20a, b ).

Ventral habitus: antennal furrows markedly delimited, nearly parallel-sided; mentum subpentagonal ( Fig. 20d ); prosternal antennal furrows on anterior margin of prosternum strongly raised and relatively long ( Fig. 20d ); prosternal process usually relatively narrow, subapical dilated portion 2.3–2.8× as wide as maximum width of 1 st antennomere, apex usually bluntly acuminate ( Fig. 20g ); lateral borders of prosternal process delimiting shallowly impressed but distinct furrows, distally terminating over predistal lateral expansions near posterior margin ( Fig. 20g ); posterior margin of mesoventrite simple, never medially incised ( Fig. 20g ); male impressions on metaventrite scarcely developed; first two visible abdominal ventrites simple in both sexes, without tufts of setae; caudal marginal lines of metacoxal cavities simple, parallel and contiguous to posterior margin of metacoxal cavities, comprising moderately deep arched impression of outer ‘axillary’ line ( Fig. 20f ); ‘axillary’ space on first abdominal ventrite reduced, ‘axillary’ angle nearly right angled ( Fig. 20f ); relatively large, long, and deeply impressed arched impressions on basal portion of last visible abdominal ventrite, frequently partially covered by distal portion of penultimate visible abdominal ventrite ( Fig. 20h ).

Appendages: male 1 st antennomere 0.7–0.9× as long as width of protibiae excluding distal teeth ( Figs. 20a, b, d ); 3 rd antennomere in both sexes 1.6–1.8× as long as wide, 0.8–0.9× as long as but distinctly thinner than 2 nd antennomere ( Fig. 20d ); 4 th and 5 th antennomeres subequal in both sexes, short, nearly as long as wide; antennal club compact, small, simple, comprising last 3 antennomeres in both sexes (8 th antennomere scarcely widened, 0.4–0.5× as wide as 9 th antennomere) ( Figs. 20a, b, d ), narrower than width of protibiae, sexual dimorphism absent; labial palpi relatively short in both sexes ( Fig. 20d ), terminal segment ~1.7× as long as wide; maxillary palpi moderately long and slender in both sexes ( Fig. 20d ), terminal segment 2.0–2.1× as long as wide; mandible mid-sized ( Fig. 20d ), apex moderately acuminate, no sexual dimorphism; tarsal claws simple, never toothed at base; tarsi of normal size and shape, 0.6–0.7× as long as corresponding tibiae ( Figs. 20a, b ); protibiae with a series of variable, even or uneven, large or small, sharp or blunt teeth on lateral margin ( Figs. 20a, b, g ; Figs. 129 a, 131 g –q, s–u in AUDISIO 1993b); lateral margin of meso- and metatibiae bearing a single usually even row of large and robust pegs ( Fig. 20k ), without U-shaped sinuosity at distal third; meso- and metatibiae of variable width, usually moderately slender and narrow ( Figs. 20a, b ), never subtrapezoidal or axe-shaped; sexual dimorphism rarely expressed in male metatibiae; tarsal plates of prolegs distinctly wider in males; posterior margin of metafemora simple in both sexes, without tubercles or projections.

Male genitalia: processes along inner side of parameres absent (Figs. 139 q–r, 142 a–o, 143 in AUDISIO 1993b), with variably incised distal margin, without deep median longitudinal desclerotization from proximal portion of tegmen extending to medial distal V-shaped excision; median lobe of aedeagus variable, without lateral emargination, narrowed and subtruncate or acuminate distally, without distal marked excision or emargination.

Female genitalia (ovipositor): variably shaped, usually large; styli short to long, simple, cylindrical, inserted in variable position prior to apex of contiguous or divergent gonostyloids (Figs. 158 b–e, m, 159 a–l in AUDISIO 1993b); each gonostyloid moderately sclerotized and frequently more darkly pigmented distally, with a simple, never indentate outer portion of basicoxites, and a single, narrow, lightly pigmented and sclerotized arcuate area along outer subdistal portion of gonostyloids. ‘Central point’ of ovipositor usually centrally located, without proximad directed spicule.

Etymology. The generic name is derived from Stachys L. ( Lamiaceae ), to emphasize the strict larval relationships of several species with members of this widespread plant genus and allied genera, and from ‘- gethes ’, to emphasize its phylogenetic relationship with Meligethes . Gender masculine.

Biology. Biology of inclusive species is incompletely known, but homogeneous within the genus. Members of Stachygethes gen. nov. are all associated as larvae with flowers of Lamiaceae (= Labiatae ), in particular Salvia L., Stachys L., Ballota L., Marrubium L., and allied genera in Palaearctic areas ( EASTON 1964a; AUDISIO 1993b, and unpublished data).

Phylogenetic position. Available morphological datasets provide evidence of a possible clade including Stachygethes gen. nov., Lamiogethes gen. nov., and potentially Rubiogethes gen. nov., Paleogethes gen. nov., Jelinekigethes gen. nov., and Astylogethes . However, phylogenetic relationships between these taxa remain unclear, and are only partially supported with molecular data ( TRIZZINO et al. 2009).

Taxonomy and geographic distribution. Stachygethes gen. nov. includes 17 described species, as well as some identified but undescribed species. The genus is mainly distributed in Europe, Anatolia, and Middle Asia ( KIREJTSHUK 1992b; AUDISIO 1993b, and unpublished data; JELÍNEK & AUDISIO 2007). Inclusive species are attributed to two formerly recognized species-groups, i.e. the ‘ Meligethes ruficornis ’, and ‘ M. assimilis ’ species-groups.

Stachygethes assimilis ( Sturm, 1845) comb. nov. Europe

Stachygethes dilutipes (Easton, 1957) comb. nov. Middle Asia

Stachygethes khnzoriani (Kirejtshuk, 1979) comb. nov. Turkey, Caucasus

Stachygethes lederi ( Reitter, 1871) comb. nov. N Africa, S Iberian Peninsula

Stachygethes maroccanus ( Easton, 1956) comb. nov. Morocco

Stachygethes nanus ( Erichson, 1845) comb. nov. Europe, N Africa, Near East, W Middle Asia Stachygethes nigerrimus ( Rosenhauer, 1856) comb. nov. N Africa, SW Europe

Stachygethes rotroui ( Easton, 1952) comb. nov. N Africa

Stachygethes ruficornis ( Marsham, 1802) comb. nov. Europe, N Africa, Near East, W Middle Asia Stachygethes saxatilis (Audisio, 1988) comb. nov. E Turkey, W Iran

Stachygethes scholzi ( Easton, 1960) comb. nov. S Italy, Sicily, W Balkans

Stachygethes strejceki (Jelínek, 1982) comb. nov. Uzbekistan

Stachygethes syriacus (C. N. F. Brisout Middle East de Barneville, 1872) comb. nov.

Stachygethes turcicus (Jelínek, 1982) comb. nov. Turkey

Stachygethes variolosus (Easton, 1964) comb. nov. S Europe, Caucasus, Turkey

Stachygethes villosus (C. N. F. Brisout Europe, N Africa de Barneville, 1863) comb. nov.

Stachygethes zarudnyi ( Kirejtshuk, 1984) comb. nov. SE Turkey, NW Iran

Figures

Fig. 20. Stachygethes Audisio & Cline, gen. nov.: a, c, f, k – S. ruficornis (Marsham, 1802); b – S. variolosus (Easton, 1964); d, e, g, h – S. assimilis (Sturm, 1845). a, b – male habitus (a – length 2.5 mm; b – length 2.5 mm); c – dorsal view of head; d – ventral view of head and anterior portion of prosternum; e – scutellum and microsetae on middle of posterior margin of pronotum; f – caudal marginal line of metacoxal cavity; g – prosternal process and mesoventrite; h – exposed portion of last visible abdominal ventrite; k – outer margin of mesotibia. Scale bars: Figs. d, f, g, h = 100 μm; Fig. e = 30 μm; Fig. k = 20 μm.