Rhinusa linariae (Panzer, 1796)
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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/8FBF961A-DC50-50CA-A826-2C05B88A8FA6 |
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treatment provided by |
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scientific name |
Rhinusa linariae (Panzer, 1796) |
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5) Rhinusa linariae (Panzer, 1796) View in CoL
Material examined.
7 mature larvae; 7 ♂ and 12 ♀ pupae. Serbia, Didič, ex Linaria vulgaris galls, 05.07.2017, leg., det. I. Toševski.
Description of mature larva
(Figs 21A, B View Figure 21 , 22A-E View Figure 22 , 23A-C View Figure 23 ). Measurements (in mm). Body length: 2.33-4.30 (avg. 3.66). The widest place in the body (meso- and metathorax) measures up to 1.16. Head width: 0.46-0.53 (avg. 0.50).
General. Body elongate, slender, strongly curved, rounded in cross section (Fig. 21A View Figure 21 ). All thoracic segments almost equal in size. Pronotal shield not pigmented. Meso- and metathorax each divided dorsally into two folds (prodorsal fold small, postdorsal prominent). Pedal folds of thoracic segments prominent, conical, and well isolated. Abdominal segments I-IV of similar size, as large as metathorax. Segments V-IX tapering towards posterior body end. Abdominal segments I-VI each divided dorsally into two variously sized folds: prodorsal small, postdorsal folds distinctly larger and much higher than prodorsal folds. Segments VII-IX dorsally undivided. Epipleural folds of segments I-VIII conical. Laterosternal and eusternal folds of segments I-VIII weakly isolated. Abdominal segment X divided into four folds of equal size. Anus situated ventrally, hidden inside ninth segment.
Thoracic and abdominal spiracles unicameral; thoracic spiracles (Figs 21A View Figure 21 , 23A View Figure 23 ) placed laterally close to mesothorax; abdominal spiracles (Figs 21A View Figure 21 , 23B, C View Figure 23 ) placed antero-laterally on segments I-VIII.
Colouration. Light yellow head (Fig. 21B View Figure 21 ). All thoracic and abdominal segments white (Fig. 21A View Figure 21 ). Cuticle covered with fine asperities.
Vestiture. Setae on body thin, transparent, different in length (very short or medium).
Head capsule (Figs 21B View Figure 21 , 22A View Figure 22 ). Head suboval, endocarinal line present, reaching to 2/3 length of frons. Frontal sutures on head indistinct, very wide. Two pairs of stemmata in the form of small dark spots (st) placed mediolaterally. Des1 short, located medially; des2 long; long des3 located anteriorly on border of the frontal suture; des4 absent; and des5 long, located anterolaterally (Fig. 22A View Figure 22 ). Fs1 and fs2 minute, located medially; fs3 absent; fs4 long, located anteriorly; and long fs5 located anterolaterally, close to antenna (Fig. 22A View Figure 22 ). Les1 and les2 medium. Epicranial area with four pes.
Antennae placed distally of the frontal suture, on the inside; membranous and distinctly convex basal article bearing one conical elongate sensorium, plus three sensilla: two basiconica and single ampullacea (Fig. 22B View Figure 22 ).
Clypeus and labrum (Fig. 22C View Figure 22 ) completely fused, trapezoidal, 3 × as wide as long, with a single short cls, localised posterolaterally; one sensillum posteromedially and single medium piliform lrs, located medially; anterior border sinuate. Epipharynx (Fig. 22C View Figure 22 ) with two finger-like als and single piliform ams, all relatively elongated; labral rods (lr) rounded, placed close to the anterior border.
Mouth parts. Mandibles (Fig. 22D View Figure 22 ) bifid, cutting edge with small protuberance; two piliform various in size mds, both located, close to lateral border. Maxillolabial complex: maxilla dark sclerotised (Fig. 22E View Figure 22 ), stipes with one stps, two pfs, and one minute mbs, stps, and both pfs1-2 relatively short; mala with four finger-like dms variable in length; three 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 single sensillum, distal palpomere with a group of five apical sensilla in terminal receptive area. Prementum (Fig. 22E View Figure 22 ) oval-shaped, with one medium prms; ligula with round margin and single medium ligs; premental sclerite undefined, weakly sclerotised, without posterior extension. Labial palpi one-segmented, vestigial, visible only under great magnification (40 ×). Each terminal receptive area with a single apical sensilla. Postmentum (Fig. 22E View Figure 22 ) with only two pms: pms1 absent; medium pms2 located mediolaterally, and relatively short pms3 located anterolaterally; membranous area covered with knobby processes.
Thorax. Prothorax (Fig. 23A View Figure 23 ) with eigth medium prns, dorsal sclerite weakly visible; two medium ps; and single short eus. Mesothorax (Fig. 23A View Figure 23 ) with one medium pds; one medium as; two medium and single minute ss; and one short ps. Chaetotaxy of metathorax (Fig. 23A View Figure 23 ) almost identical to that of mesothorax. Each pedal area of thoracic segments with five various in size pda.
Abdomen. Segments I-VIII (Fig. 23B, C View Figure 23 ) with one medium pds; one medium ss; one short ps; one short lsts; and one short eus. Abdominal segment IX (Fig. 23C View Figure 23 ) with one medium ds and two short ps.
Description of pupa
(Figs 24A-C View Figure 24 , 25A-C View Figure 25 ). Measurements (in mm). Body length: 1.66-2.66 (avg. 2.10); body width: 1.40-1.93 (avg. 1.60); thorax width: 0.90-1.18 (avg. 1.05); rostrum length: up to 0.66 on both ♀ and ♂.
Body. Integument white, moderately stout slightly curved. Head elongated protuberances (h-pr) present on head above eyes, weakly sclerotised. Rostrum moderately elongated, curved, in male usually only slightly shorter than in female almost 3 × as long as wide, reaching mesocoxae. Pronotum trapezoidal 3 × as wide as long. Pronotal protuberances (p-pr) conical, flattened, indistinct. Meso- and metanotum similar in size. Abdominal segments I-III almost identical in size; segments IV-VII tapering gradually, segment VIII narrow; segment IX reduced. Abdominal segment VIII dorsally with very small, rounded, weakly sclerotised abdominal protuberance (a-pr). Urogomphi (ur) very short, ending with sclerotised, sharp apexes (Fig. 24A-C View Figure 24 ).
Chaetotaxy. Well developed, setae variable in length, transparent. Head with one short os and short pas. Rostrum with a single short rs (Fig. 25A View Figure 25 ). Pronotum with two as, two ls, and three elongated, equal-in-length pls. Dorsal parts of meso- and metathorax with a single medium-length seta, placed medially. Apex of femora with a single long fes (Fig. 25A-C View Figure 25 ). Abdominal segments I-VII with two, equal-in-length setae dorsally: first placed posteromedially, second posterolaterally. Abdominal segment VIII with a single elongated seta medially. Each lateral part of abdominal segments I-VII with a single short seta. Ventral parts of abdominal segments I-VIII with two short setae. Abdominal segment IX with two short setae ventrally (Fig. 25A-C View Figure 25 ).
Remarks and comparative notes.
This species is widely distributed in all of Europe, Turkey, Kazakhstan, and western Siberia ( Alonso-Zarazaga et al. 2023). It was introduced in North America, where it was approved for release for biological control of invasive toadflaxes ( Linaria spp.) in Canada in 1995 and 1996 ( Sing et al. 2016). Afterwards, a population was established at sites in British Columbia and Colorado ( Sing et al. 2016; DiGirolomo et al. 2019). In Europe, the adults of this species are distinguishable from all the other species of Rhinusa by the shape of the rostrum, which is strongly curved in lateral view, and the shape of the tibiae, with the uncus of the metatibiae of the same length in both sexes and with the outer margin distinctly curved outwards apically ( Caldara and Toševski 2019).
Biological notes.
Rhinusa linariae is a univoltine root galling weevil. Gall induction and larval development are mainly recorded on Linaria vulgaris and rarely on L. genistifolia in Southeastern Europe. Adults emerge in early spring, feed, and copulate on top of the young toadflax shoots. During oviposition, females glue eggs onto toadflax roots or, rarely, below root crowns with oviposition fluid. Eggs are laid singly or in small groups. Shortly after, oviposition triggers cell proliferation, which entwists the egg, forming a round gall. Larvae feed on galled root tissue through three instars. Pupation occurs in galls, while new adults emerge in mid- to late summer or rarely stay inside galls during winter, overwintering in soil or in plant litter close to their host plant. Twenty-five years ago, R. linariae was introduced as a biological control agent for invasive toadflaxes in Canada and the USA, where it was recently confirmed as established only in British Columbia. However, the current populations are still too small to have a significant biological impact ( Sing et al. 2016; DiGirolomo et al. 2019).
Rhinusa pilosa group
Adult diagnosis. Dorsal vestiture composed of very long seta-like scales, 20-40 × longer than wide; rostrum in lateral view strongly curved; eyes strongly convex; uncus of metatibiae well developed in both sexes; body of spermatheca globose at apex.
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