Description of immature stages of Rhinusa species (Coleoptera, Curculionidae, Mecinini) with a focus on diagnostic morphological characters at the species and genus levels Author Gosik, Rafal https://orcid.org/0000-0002-2083-4905 Department of Zoology and Nature Protection, Faculty of Biology and Biotechnology, Maria Curie-Sklodowska University, Akademicka 19, 20 - 033 Lublin, Poland Author Caldara, Roberto https://orcid.org/0000-0001-9932-7078 Via Lorenteggio 37, 20146 Milan, Italy Author Tosevski, Ivo https://orcid.org/0000-0002-3666-3151 CABI, Rue des Grillons 1, 2800 Delemont, Switzerland & Institute for Plant Protection and Environment, Banatska 33, 11080 Zemun, Serbia Author Skuhrovec, Jiri https://orcid.org/0000-0002-7691-5990 Group Function of Invertebrate and Plant Biodiversity in Agro-Ecosystems, Crop Research Institute, Prague 6 - Ruzyne, Czech Republic jirislavskuhrovec@gmail.com text ZooKeys 2024 2024-03-14 1195 1 94 http://dx.doi.org/10.3897/zookeys.1195.112328 journal article http://dx.doi.org/10.3897/zookeys.1195.112328 1313-2970-1195-1 617FBE9C72D1479D83361E9325D74B93 7B852D1F498258A8AC2E473512274E16 4) Rhinusa florum (Rubsaamen, 1895) Material examined. 19 mature larvae; 20 ♂ and 6 ♀ pupae. Serbia , Vinci , ex Linaria genistifolia (L.) Miller , 05.06.2017 , leg., det. I. Tosevski . Description of mature larva (Figs 16A, B , 17A-E , 18A-C ). Measurements (in mm). Body length: 2.00-3.50 (avg. 3.00). The widest place in the body (meso- and metathorax) measures up to 1.20. Head width: 0.46-0.54 (avg. 0.52). Figure 16. Rhinusa florum (Rubsaamen, 1895) mature larva A habitus B head, frontal view. Figure 17. Rhinusa florum (Rubsaamen, 1895) mature larva, head and mouth parts A head B antenna C clypeus and labrum (left side), epipharynx (right side) D left mandible E maxillolabial complex (schemes). Abbreviations: at-antenna, lr-labral rods, sb-sensillum basiconicum, Se-sensorium, st-stemmata, setae: als -anterolateral, ams -anteromedial, cls -clypeal, des -dorsal epicranial, dms -dorsal malar, fs -frontal epicranial, les -lateral epicranial, ligs -ligular, lrs -labral, mbs -malar basiventral, mds -mandibular dorsal, mes -medial, mpxs -maxillary palp, pes -postepicranial, pfs -palpiferal, pms -postmental, prms -premental, stps -stipital, ves -ventral, vms -ventral malar. Figure 18. Rhinusa florum (Rubsaamen, 1895) mature larva, habitus A lateral view of thoracic segments B lateral view of abdominal segment I C lateral view of abdominal segments VII-X (schemes). Abbreviations: Th. 1-3-number of thoracic segments, Abd. 1-10-number of abdominal seg, setae: as -alar, ds -dorsal, eps -epipleural, eus -eusternal, lsts -laterosternal, pda -pedal, pds -postdorsal, prns -pronotal, prs -prodorsal, ss -spiracular, ps -pleural, sts -sternal. General . Body elongate, slightly curved, oblate dorsoventrally in cross section (Fig. 16A ). Prothorax prominent, pronotal shield not pigmented; meso-- and metathorax equal in size, smaller than prothorax. 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 almost equal in size folds; postdorsal folds only slightly higher than prodorsal folds. 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 divided into four folds of equal size. Anus situated ventrally, almost completely covered with the ninth abdominal segment. Thoracic spiracles bicameral, abdominal unicameral; thoracic spiracles (Fig. 16A ) placed laterally close to mesothorax; abdominal spiracles (Fig. 16A ) placed mediolaterally on segments I-VIII. Colouration . Cuticle covered with fine asperities. Brown head, medial parts of epicranium less sclerotised (Fig. 16B ). All thoracic and abdominal segments whitish (Fig. 16A ). Vestiture . Setae on body thin, yellowish, different in length (very short or medium). Head capsule (Figs 16B , 17A ). Head suboval, endocarinal line present, reaching to the 3/4 of the length of frons. Frontal sutures on head distinct, very wide. Single pair of stemmata in the form of small black spots (st) close to the end of the frontal suture. Des1 short, located in middle part of epicranium; long des2 ; long des3 located anteriorly on epicranium close to the border with the frontal suture; des4 absent; and des5 long, located anterolaterally above stemma (Fig. 17A ). Fs1 and fs2 short, located medially; fs3 absent; long fs4 located anteriorly; and long fs5 located anterolaterally, close to antenna (Fig. 17A ). Les1 and les2 medium; single medium ves . Epicranial area with five pes . Antennae placed distally of the frontal suture, on the inside; membranous and distinctly convex basal article bearing one conical, slightly elongate sensorium, plus three sensilla basiconica (Fig. 17B ). Clypeus (Fig. 17C ) trapezoidal, ~ 3.6 x as wide as long with two relatively long cls , localised posterolaterally, with one sensillum between them; basal part distinctly sclerotised; anterior border curved towards the inside. Mouth parts . Labrum (Fig. 17C ) ~ 3 x as wide as long, with three piliform lrs , variously long; lrs1 and lrs2 elongated, located medially, lrs3 short, located anterolaterally; anterior border bi-sinuate. Epipharynx (Fig. 17C ) with two relatively elongated finger-like als , almost identical in length; two piliform ams various in size; and single short finger-like mes ; labral rods (lr) close to kidney-shaped. Mandibles (Fig. 17D ) bifid, cutting edge straight; two medium piliform mds , both located in shallow pits, close to lateral border. Maxillolabial complex: maxilla dark sclerotised (Fig. 17E ), stipes with one stps , two pfs , and one very short mbs and one sensillum, stps and both pfs1-2 relatively long; mala with five finger-like dms variable in length (first and second much longer than others); five 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 six apical sensilla in terminal receptive area. Prementum (Fig. 17E ) oval-shaped, with one long prms ; ligula with round margin and three short ligs ; premental sclerite vestigial, only basal part highly sclerotised. Labial palpi one-segmented; palpi with a single pore, and a group of five apical sensilla (ampullacea) on terminal receptive area; surface of labium smooth. Postmentum (Fig. 17E ) with three pms , elongated pms1 located medially, medium pms2 located laterally, and relatively short pms3 located antero-laterally; membranous area smooth. Thorax . Prothorax (Fig. 18A ) with 12 medium prns , dorsal sclerite weakly visible; two medium ps ; and single short eus . Mesothorax (Fig. 18A ) with one minute prs , two minute and one medium pds (ordered: minute, medium, minute); one medium as ; three medium ss ; one medium eps ; one medium ps ; and single minute eus . Chaetotaxy of metathorax (Fig. 18A ) almost identical to that of mesothorax. Each pedal area of thoracic segments with four medium and one minute pda . Abdomen . Segments I-VIII (Fig. 18B, C ) with one minute prs (segment VIII without); one minute and one medium pds ; one minute and one medium ss ; two medium eps ; one medium ps ; one medium lsts ; and two short eus . Abdominal segment IX (Fig. 18C ) with one minute and medium ds ; one medium ps ; and two medium sts . Description of pupa (Figs 19A-C , 20A-C ). Measurements (in mm). Body length: 1.86-2.93 (avg. 2.60); body width: 1.66-1.86 (avg. 1.80); thorax width: 1.00-1.16 (avg. 1.06); rostrum length: up to 0.66 ♂ and 0.73 ♀. Figure 19. Rhinusa florum (Rubsaamen, 1895) pupa habitus A ventral view B lateral view C dorsal view. Figure 20. Rhinusa florum (Rubsaamen, 1895) pupa habitus A ventral view B dorsal view C lateral view (schemes). Abbreviations: a-pr-abdominal protuberances, h-pr-head protuberances, p-pr-pronotal protuberances, ur-urogomphi, setae: as -apical, d -dorsal, ds -discal, fes -femoral, l , ls -lateral, os -orbital, pls -posterolateral, rs -rostral, v -ventral. Body . Integument white, with some parts dark sclerotised; moderately stout, curved. All setae placed on dark brown spots. Head protuberances (h-pr) present on head above eyes. Rostrum rather short, in male usually only slightly shorter than in female almost 2.3 x as long as wide, reaching mesocoxae. Pronotum trapezoidal 2.4 x as wide as long. Pronotal protuberances (p-pr) conical, sclerotised, separated at bases. Meso- 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) medium, ending with sclerotised, sharp apexes (Fig. 19A-C ). Chaetotaxy . Well developed, setae medium to elongated, transparent. Head with one medium os . Rostrum with a single rs (Fig. 20A ). Pronotum with two as , one ds , two ls , and four pls variable 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. 20A-C ). Abdominal segments I-VII with six setae dorsally, variable in length: first minute, placed anteromedially; second and fourth minute; third and fifth medium, placed close to posterior margin of the segment; sixth medium, placed below stigma (on segments VI and VII all setae from second to sixth 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 setae. Abdominal segment IX with four medium setae ventrally (Fig. 20A-C ). Remarks and comparative notes. This species is distributed in Central Europe, the Balkans, the Caucasus, and the Middle East ( Alonso-Zarazaga et al. 2023 ). It is clearly distinguishable from R. antirrhini and the other species of this group by the shape of its rostrum, which in lateral view is almost straight and gradually narrowed from base to apex and not abruptly tapered at the antennal insertion. Biological notes. Rhinusa florum is a univoltine weevil that inhabits lowlands, hilly slopes, and mountain meadows at elevations up to 2000 m. The host plants are Linaria genistifolia and L. dalmatica (L.) Mill. Adults emerge in early June following the occurrence of flowering. Copulation occurs shortly thereafter, with the egg-laying period lasting from mid-June until the end of July. Oviposition occurs on the widest part of the developing ovary. During oviposition, females secrete a fluid that fixes the egg to the ovule. Females lay one egg per ovary. Egg deposition triggers a strong proliferative tissue reaction manifested as a solid, conical gall formation that grows inside the flower lumen. The galled tissue is the only resource for larval development. Pupation takes place inside the gall, and adults emerge after approximately two weeks. The adults overwinter in soil and litter close to the host plants (IT, pers. obs.). Rhinusa linariae group Adult diagnosis. Rostrum strongly curved in lateral view; outer margin of tibiae distinctly curved outwards near apex; uncus of metatibiae well developed in both sexes.