Paleogethes 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 : 415-418

21. Paleogethes Audisio & Cline , gen. nov.

( Figs. 21 a–k )

Type species. Meligethes wollastoni Easton, 1950: 309 (by present designation) [= Meligethes virescens Wollaston, 1864: 113 , non Meligethes virescens C. G. Thomson, 1862: 154 ; = Paleogethes wollastoni ( Easton, 1950) comb. nov.].

Generic description and diagnosis. The single known species (1.7–2.2 mm length; 0.7–1.0 mm width) exhibits the following combination of characters.

Body color and pubescence: pubescence silvery-whitish, fine, moderately developed, recumbent, never obscuring the brigth metallic green or rarely bicolored (head and pronotum orange-yellowish, with metallic green elytra) dorsal body surface; pronotal and elytral sides narrowly flattened, typically same color as disc. Lateral margin of pronutum and elytra with a series of faintly distinct, small and short setae, each seta 0.3–0.4× as long as those on elytral disc; posterior margin of pronotum with long, usually distally bifid microsetae, microsetae uniformly distributed on middle region anterior to scutellum ( Fig. 21g ).

Dorsal habitus: body moderately convex, long and slender ( Fig. 21a ); dorsal punctures on discal portion of pronotum larger than eye facet, usually deeply impressed and densely distributed ( Fig. 21b ); anterior margin of clypeus slightly emarginate and distinctly bordered ( Fig. 21b ), without small, faintly distinct, medial bulge; circum-ocular furrows (occipital sulci) on dorsal side of head narrow, strongly impressed, almost complete ( Fig. 21b ); eyes large and usually moderately projecting laterally ( Figs. 21a, b ); pronotum with obtusely distinct posterior angles, never directed posteriorly ( Fig. 21a ); scutellum regularly but sparsely punctured on most of exposed portion ( Fig. 21g ); elytra never transversely strigose, punctation simple, occasionally with faint traces of orange peel-like rugosity; elytral humeral angle moderately distinct, not protruding laterally ( Fig. 21a ); elytral humeral striae not distinct; elytral pre-sutural striae visible, originating at scutellar vertex, terminating at elytral apex, and delimiting on each elytron a faintly distinct and moderately raised sutural border, slightly widest at posterior third, narrower than proximal width of 3 rd antennomere; elytral apices truncately rounded in both sexes ( Fig. 21a ); pygidium partially exposed, moderately convex, apically rounded in both sexes ( Figs. 21a, h ).

Ventral habitus: antennal furrows markedly delimited, nearly parallel-sided, slightly sinuate; mentum subpentagonal, markedly transverse ( Fig. 21d ); prosternal antennal furrows on anterior margin of prosternum strongly raised and relatively long ( Fig. 21d ); prosternal process relatively wide, subapical dilated portion 2.8–2.9× as wide as maximum width of 1 st antennomere, apex bluntly acuminate ( Fig. 21f ); lateral borders of prosternal process delimiting shallowly impressed but wide and distinct furrows, distally terminating over predistal lateral expansions ( Fig. 21f ); posterior margin of mesoventrite simple, not medially incised ( Fig. 21f ); male impressions on metaventrite moderately 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. 21k ); ‘axillary’ space on first abdominal ventrite moderately developed, ‘axillary’ angle bluntly obtuse ( Fig. 21k ); large, long, and peculiarly deeply impressed arched impressions present on basal portion of last visible abdominal ventrite, rarely partially covered by distal portion of penultimate visible abdominal ventrite ( Fig. 21h ).

Appendages: male 1 st antennomere 0.8–0.9× as long as width of protibiae excluding distal teeth ( Fig. 21a ); 3 rd antennomere 2.1–2.2× as long as wide in both sexes, 0.8–0.9× as long as but distinctly thinner than 2 nd antennomere ( Fig. 21d ); 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. 21a, d ), narrower than width of protibiae, sexual dimorphism absent; labial palpi relatively short in both sexes ( Fig. 21d ), terminal segment ~1.7× as long as wide; maxillary palpi moderately long and slender in both sexes ( Fig. 21d ), terminal segment 2.0–2.1× as long as wide; mandible mid-sized ( Figs. 21a, d ), apex moderately acuminate, sexual dimorphism absent; tarsal claws simple, not toothed at base, with a minute and obtuse angulation ( Fig. 21e ); tarsi of normal size and shape, 0.6–0.7× as long as corresponding tibiae ( Figs. 21a, e ); protibiae with a series of variable, uneven, large and sharp teeth on distal portion of lateral margin ( Figs. 21a, c ; Fig. 129 o in AUDISIO 1993b); meso- and metatibiae on lateral margin bearing a single and usually even row of long and robust pegs ( Fig. 21e ), without U-shaped sinuosity at distal third; meso- and metatibiae slender and narrow ( Figs. 21a, e ), never subtrapezoidal or axe-shaped; scarcely apparent sexual dimorphism in meso- and 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. 141 i–l in AUDISIO 1993b), with narrowly and deeply incised distal margin, without deep median longitudinal desclerotization from proximal portion of tegmen extending to medial distal V-shaped excision; median lobe of aedeagus slender, without lateral emargination, narrowed and obtuse distally, without marked excision or emargination.

Female genitalia (ovipositor): small, short; styli long and pigmented, cylindrical, inserted close to apex of contiguous gonostyloids (Fig. 158 l in AUDISIO 1993b); each gonostyloid lightly sclerotized and darkly pigmented distally, with a simple, never indentate outer portion of basicoxites, and a single, narrow, more or less pigmented and sclerotized arcuate area along outer subdistal portion of gonostyloids. ‘Central point’ of ovipositor centrally located, without proximad directed spicule.

Etymology. The generic name is derived from a combination of the Greek name ‘παλαιόσ’ (= ancient), to emphasize the isolated position and likely ancient origin of the single Macaronesian species, and from ‘- gethes ’, to emphasize its phylogenetic relationship with Meligethes . Gender masculine.

Biology. The single known species is strictly associated for its larval development with flowers of Ceballosia fruticosa (L. fil.) Kunkel (= Messerschmidtia fruticosa L. fil.; Boraginaceae ) ( WOLLASTON 1864, EASTON 1956, AUDISIO 1993b).

Phylogenetic position. Available morphological datasets provide weak evidence for considering Paleogethes gen. nov. as a possible sister group to the clade containing Lamiogethes gen. nov., Rubiogethes gen. nov., and allied genera. Paleogethes wollastoni appears, in fact, to be a relictual species that is likely not too distantly related to east African members of Lamiogethes gen. nov. in the L. ruficollis / gloriosus group ( EASTON 1960, AUDISIO 1993b). Phylogenetic relationships between these taxa remain unclear, and are only partially supported with molecular data ( TRIZZINO et al. 2009).

Taxonomy and geographic distribution. This new genus includes a single species from the Canary Islands (Tenerife, Gomera, Hierro and La Palma; MACHADO & OROMI 2000).

Paleogethes wollastoni ( Easton, 1950) comb. nov. Canary Islands

Figures

Fig. 21. Paleogethes Audisio & Cline, gen. nov.: a–k – P. wollastoni (Easton, 1950). a – male habitus (length 1.9 mm); b – dorsal view of head; c – protibia; d – ventral view of head and anterior portion of prosternum; e – middle leg with outer margin of mesotibia; f – prosternal process and mesoventrite; g – anterior portion of scutellum and microsetae on middle of posterior margin of pronotum; h – exposed portion of last visible abdominal ventrite; k – ventral view of body. Scale bars: Figs. b, d, e, f, h = 100 μm; Fig. c = 20 μm; Fig. g = 10 μm; Fig. k = 200 μm.