Rhopalapion Schilsky, 1906

Giusto, Carlo, 2021, Taxonomic revision of the genus Rhopalapion Schilsky, 1906 (Coleoptera Apionidae) with description of Rhopalapion celatum n. sp. from the Turanian Region, Zootaxa 4908 (1), pp. 41-65 : 43-45

Genus Rhopalapion Schilsky, 1906

Apion subgenus Rhopalapion Schilsky, 1906 : V

Rhopalapion ; Alonso-Zarazaga 1990: 70

Pseudapion subgenus Rhopalapion ; Ehret 1994: 18

Type species. Apion longirostre Olivier, 1807 by original designation and monotypy.

Diagnosis. Within the tribe Malvapiini Alonso-Zarazaga, 1990 , Rhopalapion differs from the other genera in having an elongate body, long antennal club (3.4–4.6 times as long as wide) and strong rostral sexual dimorphism (Lr/Lp: ♁ 1.15–1.65, ♀ 2.00–3.17).

Redescription (Ƌ ♀). Body elongate; Lb: ♁ 2.30–3.65 mm, ♀ 2.25–3.87 mm. Integument dark brown to black;

antennae brown, only base of scape lightened; femora and tibiae testaceous, only apex of femora feebly darkened; apical tibial mucrones, coxae and trochanters brown to piceous. Vestiture white to cream-white composed of scales regularly distributed over entire body, concentrated around eyes to form subocular patches, on base of 3 rd elytral interval, on coxae and on almost entire thoracic and abdominal ventral surface excluding median areas of metaventrite, ventrite 1 and ventrite 5 where they are more sparse; dorsal scales slihgtly shorter than width of intervals, piliform with pointed apex to narrowly triangular with truncate apex; those on base of 3 rd elytral interval, at apex of elytra, on meso- and metanepisterna, on mesoepimera and at apex of femora always with more or less truncate apex.

Head conical and transverse with rostrum long, strongly sexually dimorphic. Male, in dorsal view, with metarostrum almost cylindrical; mesorostral dilatation obtusely rounded to hardly dentiform; prorostrum with straight sides, slightly narrowing from mesorostral dilatation to apex or with slightly concave sides (feebly narrowing from mesorostral dilatation to apical third then weakly widened to apex); fairly strongly, densely punctate from base to apical third then more sparsely punctate; matt and shagreened, shining only in apical third of prorostrum; in profile, rostrum distinctly evenly if weakly curved, more or less angulate above antennal insertion, tapering from antennal insertion to apex; ventral sulci complete, with punctures and piliform scales, separated by complete narrow median keel; latero-ventral sulci complete and distinct, with deep scaliferous punctures; subgenal sulci long, well developed; scrobes impressed, on head venter with lateral edges and complete median carina; Lr: 0.78–1.24 mm; Lpr: 0.54–0.91 mm; Lmtr: 0.21–0.39 mm; Wmsr: 0.19–0.29 mm; Lr/Wmsr: 3.38–5.17; Lr/Lp: 1.15–1.65; Lb/Lr: 2.42–3.45. Female, in dorsal view, with metarostrum almost cylindrical; mesorostrum roundly dilated; prorostrum with parallel sides or feebly widened toward apex in apical fourth; finely, sparsely punctate from base to antennal insertion then, from there to apex, increasingly finely, sparsely punctate; interspaces smooth, shining; in profile, rostrum weakly, regularly curved, imperceptibly tapered from antennal insertion to apex; ventral sulci barely visible in anterior part of submentum, separated by thin, flattened keel; latero-ventral sulci consisting of long row of fine setiferous punctures; subgenal sulci well-developed, long, thin; scrobes impressed, on head venter with lateral edges and complete median carina; Lr: 1.28–2.51 mm; Lpr: 0.95–1.94 mm; Lmtr: 0.29–0.62 mm; Wmsr: 0.15–0.25 mm; Lr/Wmsr: 6.70–13.00; Lr/Lp: 2.00–3.17; Lb/Lr: 1.28–2.12. Forehead almost flat, more or less strongly, densely punctate, sometimes with short median fovea; punctures round, 22–27 µm in diameter, separated by less than one third of their diameter or, sometimes, confluent to form striolae ; interspaces matt, microsculptured to shiny; temples and genae wrinkled, finely, sparsely punctured; gular suture broad and depressed. Eyes moderately large, regularly convex, slightly oblong. Antennae slender with fine, long erect setae; inserted at basal 0.24–0.34 (♁) or 0.20–0.28 (♀) of rostrum; La: ♁ 0.78–1.22 mm, ♀ 0.90–1.68 mm; Lc: ♁ 0.31–0.47 mm, ♀ 0.30–0.46 mm; La/Lpr: ♁ 1.12– 1.75, ♀ 0.67–1.46; La/Lc: ♁ 2.51–3.06, ♀ 2.79–3.73.

Prothorax just transverse, widest at middle to slightly longer than wide, widest just behind middle, with curved sides more constricted anteriorly than posteriorly, base slightly bisinuate; basal flange obsolete with scales arranged obliquely, not parallel to median axis; scales on front margin adpressed, directed anteriad, surpassing margin; prescutellar fovea sulciform, narrow, as long as one third prothoracic length; disc moderately convex, more or less strongly, densely punctate; punctures round to oblong, 17–27 µm in diameter, separated by less than one third of their diameter or, sometimes, confluent to form striolae ; interspaces matt, microsculptured to shiny; pronotal sides without foveae; prosternum distinctly shorter than hypomera; prosternal process between procoxae depressed; hypomeral process raised; prosternellum absent; Lp: ♁ 0.55–0.88 mm, ♀ 0.55–0.94 mm; Wp: ♁ 0.56–0.91 mm, ♀ 0.52–0.95 mm; Lp/Wp: ♁ 0.88–1.10, ♀ 0.88–1.19. Scutellum subquadrate to slightly longer than wide, with rounded apex, strongly impressed along midline; glabrous; microreticulate, matt to rather bright. Mesothoracic process slightly more prominent than metathoracic one. Metaventrite laterally globose with median depression more (♁) or less (♀) evident ending in minute oblong pit in basal third; raised mesocoxal rim obsolete. Elytra, in dorsal view, elongate in outline, with subparallel to weakly rounded sides, widening backwards, widest behind middle; humeral calli well-developed; on elytral disc, intervals 2.9–4.0 times as wide as striae, flat to feebly convex, microsculptured, fairly shiny; striae sharply margined, catenulate, with septa of punctures deepened, at apex joined as follows: 1+2+9, 3+4, 5+6, 7+8; at base, 1 st stria shortened very closely to scutellum; one sensory seta inserted at apex of 9 th interval; Le: ♁ 1.57–2.62 mm, ♀ 1.51–2.77 mm; We: ♁ 0.85–1.49 mm, ♀ 0.83–1.50 mm; Le/We: ♁ 1.66–2.01, ♀ 1.71–2.05. Hind wings well developed, functional, with no trace of radial window; anal vein complex with 1A absent, 2A weakly angled with short a1-a2 spur, 3A vestigial and 4A absent; anal notch deep, narrow. Legs rather short; femora robust, swollen, 2.55–2.90 (♁), 2.91–3.07 (♀) times as long as wide; tibiae straight, only metatibiae may appear feebly curved outwards; male protibiae armed with well-developed, sharp apical mucro or unarmed; male meso- and metatibiae armed with well-developed, blunt and oblique apical mucro; female tibiae unarmed, slightly more slender than in male; tarsi moderately elongate; 1 st segment 1.60–2.13 times as long as wide; 2 nd 1.10–1.40 times as long as wide, 0.75–0.84 times as long as 1 st; 3 rd 0.81–1.08 times as long as wide, with lobes well-developed, 0.83–1.18 times as long as 2 nd; onychium 1.27–1.81 times as long as 2 nd segment; claws robust, toothed.

Ventrites 1, 2 and 5 punctate; punctures coarse, thick, round, 15–17 μm in diameter, separated by less than half of their diameter; interspaces finely microreticulare, fairly shiny. Male pygidium (TVIII) of the concealed aspidapionine type. Male sternite IX Y-shaped with symmetrical arms. Tegmen with apodeme longer than arms of forked basal piece, arms fused to parameral plate; parameral plate long, crossed by thin median carina to base of apical membranous lobes; apical membranous lobes fairly long to long; if fairly long they are subrounded, folded at base, covered by microtrichia, separated by thin median notch; if long they are subrectangular, not folded at base, covered by microtrichia, separated by deep median notch; suprafenestral sclerites with 2–6 long outer setae and 1 shorter inner seta (occasionally 0); fenestrae well-developed. Penis, in ventral view, symmetrical, with parallel sides from base to ostium then gradually or sharply restricted to apex; apex truncate; in profile, more or less curved; endophallus, in orificial region, with two symmetrical aggregations of dense, almost uniform, minute spines. Gonocoxites elongate with reinforcing longitudinal carinae; styli inserted latero-apically with 6–9 apical setae. Spermatheca Cshaped with corpus and cornu quite similar, latter rounded at apex; ramus barely visible.

Distribution. The genus Rhopalapion is distributed throughout the Euro-Mediterranean Region, including North Africa, and in the Turanian Region to Kyrgyzstan. After its accidental introduction in 1914 in the Nearctic Region ( Tattershall & Davidson 1954), R. longirostre is also presently distributed in the United States and Canada, from coast to coast.

Bionomy. Rhopalapion species inhabit meadows, cultivated and uncultivated lands, edges of roads and paths, ruderal zones and gardens; they prefer thermophilous and xerothermophilous areas, from depressions below sea level, (- 190 m, Jordan valley, Israel) to mountain areas reaching up to 2,150 m a.s.l. ( Iran) ( Figs. 60–61 ).

Known species are associated with Malvaceae belonging to the genus Alcea L. ( Figs. 62–63 ). All attempts to confirm the large number of quotations about the discovery of R. longirostre on other plants have been in vain. Bibliographic sources referred to Malvaceae belonging to the genera Althaea L., Gossypium L., Hibiscus L. and Malva L. (= Lavatera L.) or to other plant taxa belonging to the most disparate families (e.g. Asteraceae , Brassicaceae , Fabaceae , Fagaceae , Grossulariaceae , Lamiaceae , Lauraceae , Rosaceae , Salicaceae , Ulmaceae and Urticaceae ) must be considered incorrect or accidental.

Studied material reveals that adults are active from March to November with a maximum peak from the beginning of April to mid-August. It should be noted, however, that in the literature there are quotations on the presence of adults throughout the whole year. Current knowledge on biology—unfortunately referring only to R. longirostre —reveals that females, usually from May to July, deposit eggs in floral buds that will bloom no earlier than 2 weeks. The first instar larva hatches after 3–4 days. By the time the bud has blossomed and before it falls off, all larvae migrate below the ovary and when carpels are fully developed, each larva enters into a seed and consume the entire contents of the seed chamber from within. The last instar larva bores a hole on the broadest side of the seed to permit the adult to exit. Escape hole is filled in with a secretion produced by the larva to protect pupa and developing weevil. Larval and pupal developments respectively requires 4–6 and 2–3 weeks depending on weather conditions. The adult emerges from the dry seed chamber through the escape hole after several hours. Wintering occurs under dead leaves fallen on the ground or in the ground near stems. Since mating is frequent throughout spring and summer and since from egg deposition to emergence of adult it takes 7–10 weeks, it is possible to observe the coexistence of different generations per year. For more detailed information on the biology of R. longirostre , see Tattershall & Davidson (1954), Tuttle (1954), Compte-Sart (1992), Pupier (1997), Sprick et al. (2005), Friedman & Freidberg (2007), Tuba & Lakatos (2010), Wilhelm et al. (2010), Wilhelm et al. (2011) and Bârcă et al. (2011).

Figures

FIGURES 60–63. Habitat and host plant of Rhopalapion celatum n. sp. 60: Iran: Shul pr. Shiraz.—61–63: Alcea sp. (Photos M. Košťál).