Rhinusa antirrhini (Paykull, 1800)
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publication ID |
https://dx.doi.org/10.3897/zookeys.1195.112328 |
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publication LSID |
lsid:zoobank.org:pub:617FBE9C-72D1-479D-8336-1E9325D74B93 |
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persistent identifier |
https://treatment.plazi.org/id/6415E23D-EC1F-570B-88EE-4064A7781411 |
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treatment provided by |
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scientific name |
Rhinusa antirrhini (Paykull, 1800) |
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3) Rhinusa antirrhini (Paykull, 1800) View in CoL View at ENA
Material examined.
29 mature larvae; 28 ♂ and 26 ♀ pupae. Serbia, Zemun , ex Linaria vulgaris Mill., 15.08.2017, leg., det. I. Toševski.
Description of mature larva
(Figs 11A, B View Figure 11 , 12A-E View Figure 12 , 13A-C View Figure 13 ). Measurements (in mm). Body length: 3.00-4.25 (avg. 3.60). The widest place in the body (meso- and metathorax) measures up to 1.25. Head width: 0.55-0.60 (avg. 0.56).
General. Body elongate, slender, distinctly curved, rounded in cross section (Fig. 11A View Figure 11 ). All thoracic segments almost equal in size. Meso- and metathorax each divided dorsally into two folds (prodorsal fold distinctly smaller than postdorsal fold). Pedal folds of thoracic segments isolated, conical, prominent. Abdominal segments I-VI of similar size, next segments tapering towards posterior body end. Abdominal segments I-VII each divided dorsally into two folds: prodorsal fold slightly smaller than postdorsal; both folds equally in high. Segments VIII and IX dorsally undivided. Epipleural folds of segments I-VIII conical. Laterosternal and eusternal folds of segments I-VIII conical, weakly isolated. Abdominal segment X (almost completely hidden in previous segment) divided into four folds of equal size. Anus situated ventrally.
Thoracic spiracles bicameral, abdominal unicameral; thoracic spiracles (Fig. 11A View Figure 11 ) placed laterally close to mesothorax; abdominal spiracles (Fig. 11A View Figure 11 ) placed antero-laterally on segments I-VIII.
Colouration. All thoracic and abdominal segments whitish (Fig. 11A View Figure 11 ). Cuticle densely covered with fine asperities. Dark yellow to dark brown head, medial parts of epicranium less sclerotised (Fig. 11B View Figure 11 ).
Vestiture. Setae on body thin, yellowish, different in length (very short or medium).
Head capsule (Figs 11B View Figure 11 , 12A View Figure 12 ). Head slightly narrowed bilaterally, endocarinal line present, reaching to the 2/3 of the length of frons. Frontal sutures on head very wide, indistinct. Single pair of stemmata in the form of small black spots (st) close to the end of the frontal suture. Des1 absent; des2 short, located in lateral part of epicranium; long des3 located anteriorly on epicranium on border of the frontal suture; des4 minute; and des5 long, located anterolaterally above stemma (Fig. 12A View Figure 12 ). Fs1 absent; fs2 short, located medially; fs3 absent; fs4 long, located anteriorly; and long fs5 located anterolaterally, close to antenna (Fig. 12A View Figure 12 ). Les1 short and medium les2; two short ves. Epicranial area with three pes.
Antennae placed distally of the frontal suture, on the inside; membranous and distinctly convex basal article bearing one conical sensorium, plus four sensilla ampullacea and single sensillum basiconicum (Fig. 12B View Figure 12 ).
Clypeus (Fig. 12C View Figure 12 ) trapezoidal, ~ 3.2 × as wide as long with two short cls, localised posterolaterally, with one sensillum between them; except the posterior part, whole clypeus darkly sclerotised; anterior border slightly curved towards the inside.
Mouth parts. Labrum (Fig. 12C View Figure 12 ) ~ 2.2 × as wide as long, with three piliform lrs, various long; lrs1 and lrs2 elongated, located medially, and lrs3 short, located laterally; anterior border bi-sinuate. Epipharynx (Fig. 12C View Figure 12 ) with two relatively elongated finger-like als, almost identical in length; three ams various in size; and single short finger-like mes; labral rods (lr) distinct, rounded. Mandibles (Fig. 12D View Figure 12 ) bifid, cutting edge with additional protuberance; two medium piliform mds, both located close to lateral border. Maxillolabial complex: maxilla more sclerotised than labium (Fig. 12E View Figure 12 ) stipes with one stps, two pfs and one short mbs, stps, and both pfs1-2 medium; mala with five finger-like dms variable in length; four piliform vms, medium to short in length. Maxillary palpi two-segmented; basal palpomere distinctly wider than distal one; length ratio of basal and distal palpomeres almost 1:1; basal palpomere with short mpxs and two sensilla, distal palpomere with a group of two or three apical sensilla in terminal receptive area. Prementum (Fig. 12E View Figure 12 ) close to oval-shaped, with one medium prms; ligula with round margin and two short ligs; premental sclerite vestigial, only lateral parts dark sclerotised. Labial palpi one-segmented; each palp with a single pore, and a group of one or two apical sensilla (ampullacea) on terminal receptive area; surface of labium smooth. Postmentum (Fig. 12E View Figure 12 ) with three pms, elongated pms1 located medially, long pms2 located laterally, and medium pms3 located antero-laterally; membranous area smooth.
Thorax. Prothorax (Fig. 13A View Figure 13 ) with ten relatively long prns; two medium ps; and single short eus. Mesothorax (Fig. 13A View Figure 13 ) without prs; one minute and two medium pds; one medium as; three medium ss; one medium eps; one medium ps; and single minute eus. Chaetotaxy of metathorax (Fig. 13A View Figure 13 ) almost identical to that of mesothorax. Each pedal area of thoracic segments with three medium and three minute pda.
Abdomen. Segments I-VIII (Fig. 13B, C View Figure 13 ) with one minute prs (segment VIII without); one minute and two medium pds; one minute and one medium ss; two medium eps; one minute ps; one minute lsts; and two minute eus. Abdominal segment IX (Fig. 13C View Figure 13 ) with two minute ds; two minute ps; and two minute sts.
Description of pupa
(Figs 14A-C View Figure 14 , 15A-C View Figure 15 ). Measurements (in mm). Body length: 2.35-3.30 (avg. 2.75); body width: 1.45-1.85 (avg. 1.60); thorax width: 0.90-1.20 (avg. 1.05); rostrum length: up to 0.60 ♂ and 0.75 ♀.
Body. Integument white, with some parts dark sclerotised; moderately stout, curved (Fig. 14A-C View Figure 14 ). All pronotal setae placed on pigmented spots. Head with a pair of distinct head protuberances (h-pr) above eyes. Rostrum rather short, in male usually only slightly shorter than in female: almost 3 × as long as wide, reaching mesocoxae. Pronotum trapezoidal 2 × as wide as long. Pronotal protuberances (p-pr) conical, flattened, sclerotised, separated at bases. Mesonotum and metanotum similar in size. Abdominal segments I-VI almost identical in size; segment VII semicircular; segment VIII narrow; segment IX reduced. Abdominal segment VIII dorsally with rounded, prominent, sclerotised abdominal protuberance (a-pr). Urogomphi (ur) short, ending with sclerotised, sharp apexes (Fig. 15A-C View Figure 15 ).
Chaetotaxy. Well developed, setae short to elongated, transparent. Head with one short os (Fig. 15A View Figure 15 ). Pronotum with two as, four ls, and three pls almost equally in length. Dorsal parts of meso- and metathorax with three setae of various length, placed medially. Apex of femora with a single long fes (Fig. 15A-C View Figure 15 ). Abdominal segments I-VII with five setae dorsally, variable in length: first and third minute, second, fourth and fifth medium; first to fourth placed close to posterior margin of the segment, fifth placed below stigma (on segments VI and VII all setae medium). Abdominal segment VIII with four elongated setae dorsally. Each lateral part of abdominal segments I-VII with two medium setae. Ventral parts of abdominal segments I-VIII with four medium-sized setae. Abdominal segment IX with two medium setae ventrally (Fig. 15A-C View Figure 15 ).
Remarks and comparative notes.
This species is reported from all of Europe, although it is probable that, especially in the Balkans, it is confused with several cryptic species still to be described on the basis of molecular studies ( Hernández-Vera et al. 2010; IT, pers. obs.). Rhinusa antirrhini lives on Linaria spp. other than L. vulgaris . This weevil was accidentally imported into North America at the beginning of the twentieth century, where it became important in applied entomology when proposed for the biological control of the invasive plant species L. vulgaris (see Hernández-Vera et al. 2010 and DiGirolomo et al. 2019 for references). The adult is sometimes confused with R. dieckmanni , as recently shown by Toševski et al. (2023).
Biological notes.
This univoltine weevil feeds on L. vulgaris and L. angustissima (Loisel.) Borbás, in the capsules of which larvae and pupae can be found. Adults emerge at the end of May, visiting flowers to start consuming pollen, and shortly after that, copulation begins. After mating, the females start laying eggs in well-developed floral ovaries, usually in their upper parts. When oviposition occurs, the outside of the seed capsule has a long, cone-shaped protrusion immediately above the oviposition site. This drives the formation of a semi-gall in that area. The early instar larvae feed primarily on hypertrophied seeds, while older and later instars consume abortive seeds. Most often, a single seed capsule contains one R. antirrhini larva, while at high densities, two larvae per capsule are commonly found. Development to adult takes ~ 30-50 days, depending on the environmental temperature. Newly emerged adults feed on young shoots of their host plant, expressing irregular aestivation periods until mid-autumn, when adults intensify feeding just before entering hibernation. Adults overwinter at the soil surface, sheltered below or between dry plant remains (IT, pers. obs.).
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