Measurements (in mm). Body length: 2.16–3.00. The widest point in the body (meso- and metathorax) measures up to 1.20. Head width: 0.36–0.53.

General. Body elongate or relatively elongate, slender, weakly curved, rounded in cross section.

Colouration. Pale yellow or dark brown head. All thoracic and abdominal segments white, cuticle smooth or with many reddish or brown asperities.

Vestiture. Setae on body thin, distinctly different in length (minute to very short or long).

Head capsule. Head almost oval or suboval, endocarinal line present. Frontal sutures on head distinct, extended to antennae. One stemma, in the form of a pigmented spot with convex cornea, both located on each side anterolaterally, above frontal suture. Dorsum of epicranium with three or five setae; des₁ located in central part of epicranium; des₂ lateral, sometimes absent; des₃ located anteriorly on epicranium close to frontal suture; des₄ often medially, sometimes absent; des₅ located anterolaterally. Frons with three to four fs, fs₁ absent, fs₂ located medially, fs₃ sometimes absent, fs₄ and fs₅ subequal. Head with two les, one or two ves, and two to six pes.

Antennae located at end of frontal suture on each side, membranous and distinctly convex basal article bearing one conical sensorium, relatively long.

Clypeus trapezium-shaped, ~ 3–4× as wide as long with two relatively long cls, located posterolaterally.

Mouth parts. Labrum ~ 3–4× as wide as long, with three piliform lms, relatively long; anterior margin doubly sinuate. Epipharynx with two or three long digitate als; with two or three ams, and one or without mes; labral rods indistinct. Mandibles distinctly broad, bifid, teeth of unequal height; slightly truncate; both mds relatively long, piliform, located in distinct holes. Maxilla: stipes with one stps, two pfs and sensillum, with or without mbs; mala with four or five elongated digitate dms; three or four vms, of various length; all vms distinctly shorter than dms. Maxillary palpi with two palpomeres; basal palpomere with one mxps and one sensillum; distal palpomere with one sensillum and a group of conical, cuticular apical processes. Praelabium oval, with one prms; ligula with two ligs. Labial palpi with one palpomere; palpomere with one sensillum and short, cuticular apical processes. Postlabium with two or three pms, all located laterally; membranous area finely or distinctly asperate.

Thorax. Prothorax distinctly smaller than meso- and metathorax. Spiracle unicameral, situated between pro- and mesothorax (see Material and methods). Prothorax with seven to eleven prns; two ps; and two eus. Mesothorax with or without two prs; two or three pds; one long as; two or three ss; one eps; one ps; and one or two eus. Each pedal area of thoracic segments well separated, with three or five pda.

Abdomen. Abdominal segments I–III of almost equal length, next abdominal segments shortening gradually to the terminal parts of the body. Abdominal segment X reduced to four anal lobes of unequal size, the lateral lobes being distinctly the largest, and the dorsal and ventral ones very small. Anus located terminally; ambulatory ampullae bilobate to circular. Spiracles unicameral, seven abdominal spiracles located laterally. Abdominal segments I–VI with one or two prs; one or two pds; two ss; one eps; one or two ps; one lsts and one or two eus. Abdominal segments VII–VIII without, one or two prs; one or two pds; one or two ss; one eps; one or two ps; without or one lsts; and one or two eus. Abdominal segment IX with one or two ds; one or two ps; and one or two sts. Abdominal segment X with one or two setae (ts).

Measurements (in mm). Body length: 1.87–2.73. Body width: 0.62–1.55. Thorax width: 0.67–1.12.

Body. Moderately stout, yellowish or brownish. Pronotal protuberances (p-pr) sclerotized, prominent, body covered with fine, knobby asperities; fused at base or well separated. Rostrum rather or moderately slender, ~ 4× as long as wide, extending to mesocoxae. Antennae rather short, clava smooth. Pronotum 1.5–2.2× as wide as long. Mesonotum slightly or sometimes distinctly smaller than metanotum. Abdominal segments I–V of equal length; segments VI–VIII tapering gradually to the terminal part of the body, segment IX distinctly reduced. Spiracles on abdominal segments I–V functional. Urogomphi reduced or short. Abdominal segment VIII with well visible conical abdominal protuberance dorsally (a-pr), extending the outline of the body.

Chaetotaxy. Sparse, setae of different lengths, transparent. Head with one or two os. Rostrum with or without one rs. Pronotum with one or two as, one or two ds, with two or without sls, one or three ls and three or four pls. Dorsal parts of meso- and metathorax with two or three setae. Apex of femora with one or two fes. Abdominal segments I–VIII with two or five setae dorsally. Each lateral part of abdominal segments I–VIII with one or two setae. Ventral parts of abdominal segments I–VIII with two or three setae. Abdominal segment IX with two setae ventrally.

Serbia, Bela Palanka, 43°13.150'N, 22°18.886'E, 288 m, ex Veronica anagallis-aquatica, 29.06.2020, leg. Toševski (9 larvae and 9 pupae).

(Figs 1A, B, 2A–F, 3A–C). Measurements (in mm). Body length: 2.25–2.50. The widest point in the body (meso- and metathorax) measures up to 0.95. Head width: 0.42–0.45.

General. Body elongate, slender, weakly curved, rounded in cross section (Fig. 1A).

Figure 1. 

Gymnetron tibiellum Desbrochers des Loges mature larva A habitus B head, dorsal view. Scale bars: 0.5 mm (A); 0.25 mm (B).

Colouration. Head pale brown (Fig. 1B). All thoracic and abdominal segments white, cuticle smooth (Fig. 1A).

Vestiture. Setae on body thin, yellowish, distinctly different in length (minute to very short or long).

Head capsule (Figs 1B, 2A). Head suboval, endocarinal line present, extending for 2/3 of length of frons. Frontal sutures on head very broad and distinct. Stemma, in the form of a very small pigmented spot with convex cornea. Des₁ long, located in middle of central part of epicranium; des₂ medium; des₃ long, located anteriorly on epicranium close to border with frontal suture; des₄ short; des₅ long, located anterolaterally above stemma (Fig. 2A). Fs₁ absent; fs₂ short, located medially; fs₃ short; fs₄ short, located anteriorly; and fs₅ long, located anterolaterally, close to antenna (Fig. 2A). Les₁ and les₂ as long as des₅; one short ves. Epicranial area with six postepicranial setae.

Figure 2. 

Gymnetron tibiellum Desbrochers des Loges mature larva, head and mouth parts A head B antenna C clypeus and labrum D epipharynx E left mandible F maxillolabial complex. Abbreviations: at – antenna, lr – labral rods, sa – sensillum ampullaceum, sb – sensillum basiconicum, Se – sensorium, st – stemma; setae: als – anteriolateral, ams – anteromedial, cls – clypeal, des – dorsal epicranial, dms – dorsal malar, fs – frontal epicranial, les – lateral epicranial, ligs – ligular, lms – labral, mbs – basioventral, mds – mandibular dorsal, mpxs – maxillary palps, pes – postepicranial, pfs – palpiferal, pms – postmental, prms – premental, stps – stipital, ves – ventral, vms – ventral malar.

Antennae membranous and distinctly convex basal membranous article bearing one relatively long conical sensorium and three sensilla of different types: two basiconical and one ampullaceum (Fig. 2B).

Clypeus (Fig. 2C) ~ 3× as wide as long with two medium cls, located posterolaterally, without sensillum; fused to labrum.

Mouth parts. Labrum (Fig. 2C) ~ 2× as wide as long, with three piliform lms, relatively long, of almost equal length; lms₁ located anteromedially, lms₂ located partly close to clypeus, and lms₃ located anterolaterally. Epipharynx (Fig. 2D) with three very long digitate als, almost identical in length; with two piliform, medium ams; without mes; labral rods indistinct, irregular in shape. Mandibles (Fig. 2E) with two relatively long, piliform mds, located in distinct holes. Maxilla (Fig. 2F): stipes with one stps, two pfs and with one mbs and one sensillum, stps and both pfs_1–2 relatively long; mala with four elongate, digitate dms; four vms, almost equal in length. Maxillary palpi with two palpomeres; length ratio of basal and distal palpomeres: 1:0.6. Praelabium (Fig. 2F) oval, with one long prms; ligula with sinuate margin and two short ligs; premental sclerite broad, well visible. Postlabium (Fig. 2F) with three pms, medium pms₁ located medially, elongated pms₂ located laterally, and medium pms₃ located anterolaterally; membranous area sparsely and finely asperate.

Thorax. Prothorax (Fig. 3A) with 11 long and one short to minute prns, small pigmented dorsal sclerite present with five long and one short prns, this sclerite subdivided into two triangular plates medially; two long ps; and two short to very short eus. Mesothorax (Fig. 3A) without prs, two long and one short pds; one long as; two long and one very short to minute ss; one long eps; one long ps; and two short eus. Chaetotaxy of metathorax (Fig. 3A) almost identical to that of mesothorax. Each pedal area of thoracic segments well separated, with three long and two short pda.

Figure 3. 

Gymnetron tibiellum Desbrochers des Loges mature larva, habitus A lateral view of thoracic segments B lateral view of abdominal segment I C lateral view of abdominal segments VI–X. Abbreviations: Th1–3 – numbers of thoracic segments, Ab1–10 – numbers of abdominal segments, 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, ts – terminal.

Abdomen. Spiracles on abdominal segments I–VI close to anterior margin, functional, spiracles on abdominal segment VII not functional. Abdominal segments I–VII (Fig. 3B, C) with two minute prs; two long pds; one long and one very short to minute ss; one short eps; one short ps; one short lsts; and two very short and sometimes one additional minute eus. Abdominal segment VIII (Fig. 3C) with two minute prs; two long pds; one very short to minute ss; one short eps; one short ps; one short lsts; and two very short and sometimes one additional minute eus. Abdominal segment IX (Fig. 3C) with two short ds; two short ps; and two very short sts. Abdominal segment X (Fig. 3C) with two minute setae (ts).

(Figs 4A–C, 5A–C). Measurements (in mm). Body length: 1.87–2.50. Body width: 0.62–1.25. Thorax width: 0.67–1.12.

Figure 4. 

Gymnetron tibiellum Desbrochers des Loges pupa habitus A ventral view B lateral view C dorsal view. Scale bars: 0.5 mm.

Body. Brownish, pronotal protuberances (p-pr) sclerotized, covered with conical asperities; apical parts of femora, head, rostrum and pronotum darker than rest of body. Rostrum moderately slender. Pronotal protuberances fused at base. Pronotum 1.5× as wide as long. Mesonotum slightly smaller than metanotum. Urogomphi in form of minute sclerotized protuberances, almost invisible. Abdominal segment VIII dorsally with rounded, prominent abdominal protuberance (a-pr) (Fig. 5A–C).

Chaetotaxy. Sparse, setae short to medium, transparent. Head with one medium os. Rostrum without setae (Fig. 5B). Pronotum with one as, one ds, two sls, one ls and three pls almost equal in length. Dorsal parts of meso- and metathorax with two setae of various length, placed medially. Apex of pro- and mesofemora with two medium-sized fes, metafemora with one seta (Fig. 5A–C). Abdominal segments I–VIII with three short setae of equal length dorsally: first placed medially, the next two more laterally. Each lateral part of abdominal segments I–VIII with single, medium-sized seta. Ventral parts of abdominal segments I–VIII with three medium-sized setae. Abdominal segment IX with two minute setae ventrally (Fig. 5A–C).

Figure 5. 

Gymnetron tibiellum Desbrochers des Loges pupa habitus A ventral view B dorsal view C lateral view. Abbreviations: a–pr – abdominal protuberances, p–pr – pronotal protuberances, ur – urogomphi; setae: as – apical, d – dorsal, ds – discal, fes – femoral, l, ls – lateral, os – orbital, pls – posterolateral, sls – superlateral, v – ventral.

The immature stages of G. tibiellum were collected from capsules of Veronica anagallis-aquatica L. Previously, nothing was known about the biology of this species. The adults are active from mid-April following the appearance of the host plants. Oviposition takes place from early June until mid-August. The presence of larvae inside the seed capsules is readily detected from the dark colour of the deposited frass. The biologies of G. tibiellum and G. veronicae are very similar but no competition between these two weevil species has been observed in over 500 dissected seeds capsules where they occur in syntopy.

Gymnetron tibiellum is widely distributed in the south-eastern part of central Europe, Italy, the Balkans, Caucasus, Anatolia and the Middle East (Alonso-Zarazaga et al. 2017). The adults of this species are very closely related to G. veronicae, from which they differ by the shape of the rostra and the penis (Caldara 2008a). This close relationship was confirmed here by several characters which the immature stages have in common, although differences in several other characters of both larvae and pupae readily discriminate these two species.

Serbia, Gornji Milanovac, Donja Vrbava, GPS 44°1.663'N, 20°34.496'E, 370 m, ex Veronica anagallis-aquatica, 20.06.2020, leg. Toševski (4 larvae and 4 pupae).

(Figs 6A, B, 7A–F, 8A–C). Measurements (in mm). Body length: 2.16–3.00. The widest point in the body (meso- and metathorax) measures up to 1.00. Head width: 0.50–0.53.

Figure 6. 

Gymnetron veronicae (Germar) mature larva A habitus B head, dorsal view. Scale bars: 0.5 mm (A); 0.25 mm (B).

General. Body elongate, slender, weakly curved, rounded in cross section (Fig. 6A).

Colouration. Head dark brown (Fig. 6B). All thoracic and abdominal segments white with numerous reddish or brown asperities (Fig. 6A).

Vestiture. Setae on body thin, orange, distinctly different in length (minute to very short or long).

Head capsule (Figs 6B, 7A). Head suboval, flattened laterally, endocarinal line present, clearly extending to half the length of frons. Frontal sutures on head very broad and distinct. Stemma, in the form of a very small pigmented spot with convex cornea. Des₁ long, located in middle of the central part of epicranium; des₂ short, placed medially; des₃ relatively long, located anteriorly on epicranium close to border with frontal suture; des₄ short, placed above frontal suture; des₅ long, located anterolaterally (Fig. 7A). Fs₁ short; fs₂ absent; fs₃ located medially; fs₄ short, located anteriorly; and fs₅ long, located anterolaterally, close to antenna (Fig. 7A). Les₁ and les₂ as long as des₅; one ves minute. Epicranial area with four postepicranial setae.

Figure 7. 

Gymnetron veronicae (Germar) mature larva, head and mouth parts A head B antenna C clypeus and labrum D epipharynx E left mandible F maxillolabial complex. Abbreviations: at – antenna, lr – labral rods, sa – sensillum ampullaceum, sb – sensillum basiconicum, Se – sensorium, st – stemma; setae: als – anteriolateral, ams – anteromedial, cls – clypeal, des – dorsal epicranial, dms – dorsal malar, fs – frontal epicranial, les – lateral epicranial, ligs – ligular, lms – labral, mbs – basioventral, mds – mandibular dorsal, mpxs – maxillary palps, pes – postepicranial, pfs – palpiferal, pms – postmental, prms – premental, stps – stipital, ves – ventral, vms – ventral malar.

Antennae membranous and distinctly convex basal membranous article bearing one relatively long conical sensorium and six sensilla different in length (four basiconica and two ampullacea) (Fig. 7B).

Clypeus (Fig. 7C) ~ 3× as wide as long with two medium cls, located posterolaterally, without sensillum; fused to labrum.

Mouth parts. Labrum (Fig. 7C) ~ 4× as wide as long, three piliform lms, relatively long but of different lengths; lms₁ located anteromedially, lms₂ located partly close to clypeus, and lms₃ located anterolaterally, lms₁ and lms₂ relatively elongate, lms₃ short. Epipharynx (Fig. 7D) with two very long digitate als, almost identical in length; with three ams of different length, ams₁ and ams₂ piliform and short, ams₃ digitate and enlarged in middle; without mes; labral rods indistinct, irregular in shape. Mandibles (Fig. 7E) with two relatively long, piliform mds, located in distinct holes. Maxilla (Fig. 7F): stipes with one stps, two pfs and one minute mbs and one sensillum, stps and both pfs relatively long; mala with five medium, digitate dms; four vms, of different lengths, two setae very short, and two setae minute. Maxillary palpi with two palpomeres; length ratio of basal and distal palpomeres: 1:0.5. Praelabium (Fig. 7F) suboval-shaped, with one medium prms; ligula with sinuate margin and two very short ligs; premental sclerite broad, well visible. Postlabium (Fig. 7F) with three pms: pms₁ very long; pms₂ short, located medially; pms₃ located laterally; membranous area densely and finely asperate.

Thorax. Prothorax (Fig. 8A) with seven long and one short prns, small pigmented dorsal sclerite present with three long prns, this sclerite subdivided into two triangular plates medially; two long ps; and two short to very short eus. Mesothorax (Fig. 8A) with two very short to minute prs; one short and two long pds; one long as; one long and two very short to minute ss; one long eps; one long ps; and two short eus. Chaetotaxy of metathorax (Fig. 8A) almost identical to that of mesothorax. Each pedal area of thoracic segments well separated, with three long and two very short to minute pda.

Figure 8. 

Gymnetron veronicae (Germar) mature larva, habitus A lateral view of thoracic segments B lateral view of abdominal segment I C lateral view of abdominal segments VI–X. Abbreviations: Th1–3 – numbers of thoracic segments, Ab1–10 – numbers of abdominal segments; 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, ts – terminal.

Abdomen. Spiracles on abdominal segments I–VI close to the anterior margin and functional, spiracles on abdominal segment VII not functional, and abdominal segment VIII with atrophied spiracles. Abdominal segments I–VII (Fig. 8B, C) with two minute prs (segment VII with one prs); one long and one minute pds; one long and one very short to minute ss; one long eps; one relatively long ps; one short lsts; and two very short and sometimes one additional minute eus. Abdominal segment VIII (Fig. 8C) with one minute prs; one long pds; one very short to minute ss; one long eps; one relatively long ps; one short lsts; and two very short and sometimes one additional minute eus. Abdominal segment IX (Fig. 8C) with one relatively long ds; one relatively long ps; and one short to very short sts. Abdominal segment X (Fig. 8C) with one very short seta (ts).

(Figs 9A–C, 10A–C). Measurements (in mm). Body length: 2.12–2.32. Body width: 1.25–1.23, Thorax width: 0.70–0.80.

Figure 9. 

Gymnetron veronicae (Germar) pupa habitus A ventral view B lateral view C dorsal view. Scale bars: 0.5 mm.

Body. Brownish, pronotal protuberances (p-pr) sclerotized, covered with conical asperities; apical parts of femora, head, rostrum and pronotum darker than rest of body. Rostrum moderately slender. Pronotal protuberances almost completely fused. Pronotum twice as wide as long. Mesonotum slightly smaller than metanotum. Urogomphi short, conical, with sclerotized apices. Abdominal segment VIII with rounded, prominent abdominal protuberance dorsally (a-pr) (Fig. 10A–C).

Chaetotaxy. Sparse, setae short to medium, transparent. Head with one medium os. Rostrum without setae (Fig. 10B). Pronotum with two elongate as, one ds, one sls, and three pls, all of almost equal length. Dorsal parts of meso- and metathorax with three setae of various length, situated medially. Apex of femora with two medium-sized fes (Fig. 10A–C). Abdominal segments I–VIII with four medium to short setae placed in horizontal line medially. Each lateral part of abdominal segments I–VIII with two setae of various size. Ventral parts of abdominal segments I–VIII with three medium setae. Abdominal segment IX with two minute setae ventrally (Fig. 10A–C).

Figure 10. 

Gymnetron veronicae (Germar) pupa habitus A ventral view B dorsal view C lateral view. Abbreviations: a–pr – abdominal protuberances, p–pr – pronotal protuberances, ur – urogomphi; setae: as – apical, d – dorsal, ds – discal, fes – femoral, l – lateral, os – orbital, pls – posterolateral, sls – superlateral, v – ventral.

The larva was already known to feed on the ovary of Veronica beccabunga L, where it pupates and develops to the adult stage, and the adult was also collected on V. anagallis-aquatica L. and V. scutellata L. (Hoffmann 1958; Koch 1992; Sprick 1997). We can now confirm that at least V. anagallis-aquatica L. must be another host plant. The biology of this weevil species is the same as that of G. tibiellum.

The adult of this species, widely distributed throughout Europe (Alonso-Zarazaga et al. 2017), is closely related to G. tibiellum, but with which it is sympatric only in south-eastern Europe. The two species differ mainly in the shapes of the rostra and the penis. Examination of the larvae confirms the relationship between them: they share the praedorsal segment on the abdominal segments with two pds, the epicranium with fs₃ and the labral setae in one line. However, the larva of G. veronicae differs from that of G. tibiellum by the cuticle of the body covered with numerous reddish or brown asperities and setae emerging from black spots, the dark brown not pale yellow head, and the epipharynx with two (not three) als and three (not two) ams. The pupae also have many characters in common (see the key), but clearly differ by the number of setae as, ls and sls on the pronotum, those on the meso- and metathorax, and on the dorsal parts of abdominal segments I–VII.

Serbia, Kalna, GPS 43°24.673'N, 22°25.737'E, 365 m, ex Veronica hederophylla, 20.06.2020, leg. Toševski (20 larvae); Serbia, Zemun, GPS 44°51.313'N, 20°22.625'E, 105 m, ex V. opaca, 19.06.2020, leg. Toševski (4 larvae and 2 pupae).

(Figs 11A, B, 12A–F, 13A, B). Measurements (in mm). Body length: 2.20–2.33. The widest point in the body (meso- and metathorax) measures up to 0.86. Head width: 0.36–0.50.

Figure 11. 

Gymnetron rotundicolle Gyllenhal mature larva A habitus B head, dorsal view. Scale bars: 0.5 mm (A); 0.25 mm (B).

General. Body relatively elongate, distinctly curved, rounded in cross section (Fig. 11A).

Colouration. Head pale yellow (Fig. 11B). All thoracic and abdominal segments white, cuticle smooth (Fig. 11A).

Vestiture. Setae on body thin, transparent, distinctly different in length (minute to very short or medium).

Head capsule (Figs 11B, 12A). Head suboval, endocarinal line present, shorter than half the length of frons. Frontal sutures on head of medium width, distinct. Stemma, in form of distinct, black pigmented spot with convex cornea. Des₁ short, located in middle of central part of epicranium; des₂ short, located in middle of central part of epicranium; medium size des₃ located anteriorly on epicranium close to border with frontal suture; des₄ short, located between des₂ and des₃; des₅ of medium size, located anterolaterally (Fig. 12A). Fs₁ absent; fs₂ very short to minute, located medially; fs₃ absent; fs₄ medium, located anteriorly; and fs₅ relatively long, located anterolaterally, close to antenna (Fig. 12A). Les₁ and les₂ as long as des₅; two ves short. Epicranial area with four postepicranial setae (pes).

Figure 12. 

Gymnetron rotundicolle Gyllenhal mature larva, head and mouth parts A head B antenna C clypeus and labrum D epipharynx E left mandible F maxillolabial complex. Abbreviations: at – antenna, clss – clypeal sensillium, lr – labral rods, sb – sensillum basiconicum, Se – sensorium, st – stemma; setae: als – anteriolateral, ams – anteromedial, cls – clypeal, des – dorsal epicranial, dms – dorsal malar, fs – frontal epicranial, les – lateral epicranial, ligs – ligular, lms – labral, mbs – basioventral, mds – mandibular dorsal, mes – median, mpxs – maxillary palps, pes – postepicranial, pfs – palpiferal, pms – postmental, prms – premental, stps – stipital, ves – ventral, vms – ventral malar.

Antennae membranous and distinctly convex basal membranous article bearing one relatively long conical sensorium and three sensilla basiconica (Fig. 12B).

Clypeus (Fig. 12C) ~ 3× as wide as long with two relatively long cls: cls₁ located posterolaterally, cls₂ located posteromedially, and one sensillum between setae; not fused with labrum.

Mouth parts. Labrum (Fig. 12C) ~ 3× as wide as long, with three piliform lms, relatively long, of almost equal length; lms₁ located posteromedially, close to clypeus, lms₂ located anteromedially, and lms₃ located anterolaterally. Epipharynx (Fig. 12D) with three very long digitate als, almost identical in length, two piliform ams almost equal in length and one mes; labral rods indistinct, enlarged anteriorly. Mandibles (Fig. 12E) with two relatively long, piliform mds, located in distinct holes. Maxilla (Fig. 12F): stipes with one stps, two pfs, one mbs and sensillum, stps and pfs_1–2 long, mbs very short; mala with five relatively long, digitate dms; four vms, different in length, one setae very short, and three setae minute. Maxillary palpi with two palpomeres; length ratio of basal and distal palpomeres: 1:0.5. Praelabium (Fig. 12F) oval, with one relatively long prms; ligula with sinuate margin and two very short ligs and one sensillum; premental sclerite broad, readily visible at sides but almost invisible in middle. Postlabium (Fig. 12F) with three pms, very long pms₂, and very short to short pms₁ and pms₃, all located laterally; membranous area sparsely and finely asperate.

Thorax. Prothorax (Fig. 13A) with six relatively long and one short to very short prns, pigmented dorsal sclerite present with four relatively long prns, this sclerite subdivided into two triangular plates medially; two relatively long ps; and one short eus. Mesothorax (Fig. 13A) with two very short to minute prs, one relatively long and two short to very short pds; one relatively long as; two relatively long ss; one relatively long eps; one relatively long ps; and one short eus. Chaetotaxy of metathorax (Fig. 13A) almost identical to that of mesothorax. Each pedal area of thoracic segments well separated, with three long pda.

Figure 13. 

Gymnetron rotundicolle Gyllenhal mature larva, habitus A lateral view of thoracic segments B lateral view of abdominal segment I C lateral view of abdominal segments VI–X. Abbreviations: Th1–3 – numbers of thoracic segments, Ab1–10 – numbers of abdominal segments; 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, ts – terminal.

Abdomen. Spiracles on abdominal segments I–VI close to the anterior margin and functional, spiracles on abdominal segment VII not functional, and abdominal segment VIII with atrophied spiracles. Abdominal segments I–VI (Fig. 13B, C) with one very short to minute prs; one relatively long and one very short pds; one relatively long and one very short to minute ss; one relatively long eps; two very short ps; one very short lsts; and one very short to minute eus. Abdominal segments VII–VIII (Fig. 13C) without prs; with one relatively long pds; one very short to minute ss; one relatively long eps; two very short ps; one very short lsts; and one very short to minute eus. Abdominal segment IX (Fig. 13C) with one very short ds; one very short ps; and two very short sts. Abdominal segment X (Fig. 13C) with one very short to minute seta (ts).

(Figs 14A–C, 15A–C). Measurements (in mm). Body length: 2.20–2.37. Body width: 1.12–1.42, Thorax width: 0.70–0.85.

Figure 14. 

Gymnetron rotundicolle Gyllenhal pupa habitus A ventral view B lateral view C dorsal view. Scale bars: 0.5 mm.

Body. Yellowish, pronotal protuberances (p-pr) weakly sclerotized, with serrated margins; apical parts of femora brownish. Rostrum slender. Pronotum twice as wide as long. Pronotal protuberances fused at basis. Mesonotum slightly smaller than metanotum. Urogomphi reduced, conical, with sclerotized apex. Abdominal segment VIII with rounded, prominent abdominal protuberance dorsally (a-pr) (Fig. 15A–C).

Figure 15. 

Gymnetron rotundicolle Gyllenhal pupa habitus A ventral view B dorsal view C lateral view. Abbreviations: a–pr – abdominal protuberances, p–pr – pronotal protuberances, ur – urogomphi; setae: as – apical, d – dorsal, ds – discal, fes – femoral, l, ls – lateral, os – orbital, pls – posterolateral, v – ventral.

Chaetotaxy. Sparse, setae short to medium, transparent. Head with one short os. Rostrum without setae (Fig. 14B). Pronotum with two as, one ds, and three pls equal in length. Dorsal parts of meso- and metathorax with three setae of different length, situated medially. Apex of femora with one medium fes (Fig. 15A–C). Abdominal segments I–VIII with two short, equally long setae dorsally: one situated medially, the other mediolaterally. All dorsal abdominal setae almost equal in length, short. Each lateral part of abdominal segments I–VIII with two setae of various length (one short, one minute). Ventral parts of abdominal segments I–VIII with three medium setae. Abdominal segment IX with two very short setae ventrally (Fig. 15A–C).

The adults of G. rotundicolle were previously recorded as collected on two species of Veronica: V. persica Poiret in Italy and Switzerland (Caldara 2008b; Germann et al. 2013), and V. chamaedrys L. in the Czech Republic and Slovakia (Krátký and Trnka 2012; Krátký 2013). The reports of Veronica hederifolia L. and V. opaca Fr. as host plants of this weevil are new data. The adults appear in early spring (mid-March), feeding on the upper leaves of newly growing shoots of the host. Oviposition takes place in the seed capsules, in which the larvae complete their development. The presence of larvae inside seed capsules can be detected from the dark colour of their frass.

The first findings of this originally central Asian species in many countries of central and southern Europe (Italy, Switzerland, France, Germany, Czech Republic, Slovakia, Hungary, Poland) have been reported in many faunistic papers during the last 15 years (Strejček 2007; Caldara 2008b; Krátký and Trnka 2012; Krátký 2013; Germann et al. 2013; Reibnitz 2013; Podlussány et al. 2017; Wanat and Ruta 2018; Nolte and Haag 2019). These papers indicate with a high degree of certainty that this species only recently colonized areas where a few years ago it was absent, in contrast to its host plants (Caldara 2008b; Germann et al. 2013).

Serbia, Pirot, Ponor, GPS 43°11.013'N, 22°25.067'E, 686 m, ex Veronica austriaca subsp. jacquinii, 20.06.2020, leg. Toševski (35 larvae and 11 pupae).

(Figs 16A, B, 17A–F, 18A, B). Measurements (in mm). Body length: 2.33–2.66. The widest point in the body (meso- and metathorax) measures up to 1.00. Head width: 0.50–0.53.

General. Body elongate, slender, weakly curved, rounded in cross section (Fig. 16A).

Figure 16. 

Gymnetron melanarium (Germar) mature larva A habitus B head, dorsal view. Scale bars: 0.5 mm (A); 0.25 mm (B).

Colouration. Head pale yellow (Fig. 16B). All thoracic and abdominal segments smooth (Fig. 16A).

Vestiture. Setae on body thin, yellow, distinctly different in length (minute to very short or long).

Head capsule (Figs 16B, 17A). Head almost oval, endocarinal line present, extending distinctly to 3/4 of the length of frons. Frontal sutures on head distinct. Stemma, in form of pigmented spot with convex cornea. Des₁ medium, located in middle of central part of epicranium; medium des₂; medium des₃ located anteriorly on epicranium, close to border with frontal suture; medium des₄; medium des₅ placed laterally (Fig. 17A). Fs₁ absent; fs₂ medium, located medially; fs₃ absent; fs₄ medium, located anteriorly; and fs₅ long, located anterolaterally, close to antenna (Fig. 17A). Les₁ medium and les₂ as long as des₅; single ves medium. Epicranial area with six postepicranial setae.

Figure 17. 

Gymnetron melanarium (Germar) mature larva, head and mouth parts A head B antenna C clypeus and labrum D epipharynx E left mandible F maxillolabial complex. Abbreviations: at – antenna, clss – clypeal sensillium, lr – labral rods, sa – sensillum ampullaceum, sb – sensillum basiconicum, Se – sensorium, st – stemma; setae: als – anteriolateral, ams – anteromedial, cls – clypeal, des – dorsal epicranial, dms – dorsal malar, fs – frontal epicranial, les – lateral epicranial, ligs – ligular, lms – labral, mds – mandibular dorsal, mes – median, mpxs – maxillary palps, pes – postepicranial, pfs – palpiferal, pms – postmental, prms – premental, stps – stipital, ves – ventral, vms – ventral malar.

Antennae membranous and distinctly convex basal membranous article bearing one relatively long conical sensorium and four sensilla: three basiconica and single ampullaceum (Fig. 17B).

Clypeus (Fig. 17C) ~ 3× as wide as long with two relatively long cls, located posterolaterally, with single sensillum; fused to labrum.

Mouth parts. Labrum (Fig. 17C) ~ 3× as wide as long, with three piliform lms, relatively long, lms₃ slightly shorter than others; lms₁ located anteromedially, lms₂ located partly close to clypeus, and lms₃ located anterolaterally. Epipharynx (Fig. 17D) with three very long digitate als, almost identical in length; with two piliform ams, equal in length, and one short, digitate mes; labral rods indistinct, narrow. Mandibles (Fig. 17E) with two relatively long, piliform mds, located in distinct holes. Maxilla (Fig. 17F): stipes with one stps, two pfs and one sensillum, without mbs; stps and both pfs long; mala with five moderately elongate digitate dms; four vms, different in length, two setae short, and two setae very short. Maxillary palpi with two palpomeres; length ratio of basal and distal palpomeres: 1:1.2. Praelabium (Fig. 17F) oval, with one medium prms; ligula with rounded margin and two very short ligs; premental sclerite broad, well visible. Postlabium (Fig. 17F) with three pms, short pms₁, very long pms₂ and short pms₃, all located laterally; membranous area densely and distinctly asperate.

Thorax. Prothorax (Fig. 18A) with nine long and one minute prns; two long ps; and two very short eus. Mesothorax (Fig. 18A) with two minute prs; one medium and two long pds; one long as; two long and one minute ss; one long eps; one long ps; and one short eus. Chaetotaxy of metathorax (Fig. 18A) almost identical to that of mesothorax. Each pedal area of thoracic segments well separated, with one long, two medium and two very short to minute pda.

Figure 18. 

Gymnetron melanarium (Germar) mature larva, habitus A lateral view of thoracic segments B lateral view of abdominal segment I C lateral view of abdominal segments VI–X. Abbreviations: Th1–3 – numbers of thoracic segments, Ab1–10 – numbers of abdominal segments; 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, ts – terminal.

Abdomen. Spiracles on abdominal segments I–VI placed medially and functional, spiracles on abdominal segment VII not functional, and abdominal segment VIII with atrophied spiracles. Abdominal segments I–VI (Fig. 18B, C) with one minute prs; one long and one medium pds; one long and one very short to minute ss; one long eps; one relatively long ps; without lsts and two very short eus. Abdominal segments VII–VIII (Fig. 18C) without prs; one long and one medium pds; one very short to minute ss; one long eps; one long ps; and two very short eus. Abdominal segment IX (Fig. 18C) with one relatively long ds; one relatively long ps; and one medium sts. Abdominal segment X (Fig. 18C) with one very short seta (ts).

(Figs 19A–C, 20A–C). Measurements (in mm). Body length: 2.12–2.32. Body width: 1.25–1.32. Thorax width: 0.75–0.82.

Body. Yellowish, pronotal protuberances (p-pr) sclerotized, smooth; head, rostrum, antennae, dorsal parts of meso- and metanotum, and apical parts of femora brownish. Rostrum rather slender. Pronotal protuberances well separated. Pronotum 1.8× as wide as long. Mesonotum slightly smaller than metanotum. Urogomphi reduced, conical, with sclerotized apex. Abdominal segment VIII with conical abdominal protuberance dorsally (a-pr) having acute, sclerotized apex (Fig. 19A–C).

Figure 19. 

Gymnetron melanarium (Germar) pupa habitus A ventral view B lateral view C dorsal view. Scale bars: 0.5 mm.

Chaetotaxy. Sparse, setae rather short to moderately elongate, transparent. Head with two os, different in length. Rostrum with one rs. Setae on head and rostrum straight, as long as those on prothorax (Fig. 20B). Pronotum with two as, two ls, two ds and four pls; ds_1–2 and ls₂ slightly shorter than other pronotal setae. Dorsal parts of meso- and metathorax with two setae placed medially. Apex of femora with two fes equal in length (Fig. 20A–C). Abdominal segments I–VIII with five short, equally long setae dorsally: first placed antero-medially, the others distributed in regular line along posterior margin of segment. All dorsal abdominal setae short, almost equal in length. Each lateral part of abdominal segments I–VIII with one elongated seta. Ventral parts of abdominal segments I–VIII with three medium setae. Abdominal segment IX with two very short setae ventrally (Fig. 20A–C).

Figure 20. 

Gymnetron melanarium (Germar) pupa habitus A ventral view B dorsal view C lateral view. Abbreviations: a–pr – abdominal 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.

Previously the larva of this species was observed on Veronica serpyllifolia L., on the stems where it produces a small uni- or bilocular gall in which metamorphosis takes place. The adult emerges from the gall at the end of summer and hibernates in the soil (Hustache 1931; Hoffmann 1958). The adult has also been collected on other Veronica species such as V. agrestis L., V. austriaca subsp. austriaca L., V. chamaedrys L., V. officinalis L, and V. teucrium (L.) D.A. Webb (Hoffmann 1958; Koch 1992; Sprick 1997). In Serbia, the development of G. melanarium is restricted to the seed capsules of Veronica austriaca subsp. jacquinii (Baumg.) Watzl, which is new information. Nearly 90% of the seed capsules are infested with one or two larvae. The larvae are seed feeders and development occurs in the basal part of the strongly flattened, glossy and glabrous seed capsules with no visible sign of larval presence. Oviposition takes place from mid-May onwards and the new generation of adults emerges during July.

This species belongs to a group of very similar species characterized by slender subrectangular elytra, rostrum in lateral view tapered from the antennal insertion to the apex, and short protibiae in the female. There are no particular phylogenetic affinities with the adult (see Caldara 2008a) and pupal stages (abdominal protuberance short, triangular, head with 2 os) of the other species described here. By contrast, the larvae share several characters with G. rotundicolle, e.g., the praedorsal segment on abdominal segments with one pds, the epicranium lacking fs₃, and the conical layout of the labral setae.

Serbia, Boljetin, GPS 44°30.973'N, 22°0.921'E, 139 m, ex gall Veronica anagallis-aquatica, 16.07.2012, leg. Toševski (3 larvae and 1 pupa).

(Figs 21A, B, 22A–F, 23A–C). Measurements (in mm). Body length: 2.25–2.46. The widest point in the body (meso- and metathorax) measures up to 1.20. Head width: 0.40–0.51.

General. Body elongate, slender, weakly curved, rounded in cross section (Fig. 21A).

Figure 21. 

Gymnetron villosulum Gyllenhal mature larva A habitus B head, dorsal view. Scale bar: 1 mm.

Colouration. Head dark brown (Fig. 21B). All thoracic and abdominal segments white with many reddish or brown asperities (Fig. 21A).

Vestiture. Setae on body thin, orange, distinctly different in length (minute to very short or long).

Head capsule (Figs 21B, 22A). Head suboval, flattened laterally, endocarinal line present, clearly extending to 1/3 of the length of frons. Frontal sutures on head very broad and distinct. Stemma, in the form of a very small pigmented spot with convex cornea. Des₁ short, located in middle of central part of epicranium; des₂ absent; relatively long des₃ located anteriorly on epicranium close to border with frontal suture; des₄ absent; des₅ long, located anterolaterally (Fig. 22A). Fs₁ absent; fs₂ relatively long, located medially; fs₃ absent; fs₄ relatively long, located anteriorly; and fs₅ long, located anterolaterally, close to antenna (Fig. 22A). Les₁ and les₂ as long as des₅; ves short. Epicranial area with two postepicranial setae.

Figure 22. 

Gymnetron villosulum Gyllenhal mature larva, head and mouth parts A head B antenna C clypeus and labrum D epipharynx E left mandible F maxillolabial complex. Abbreviations: at – antenna, lr – labral rods, sb – sensillum basiconicum, Se – sensorium, st – stemma; setae: als – anteriolateral, ams – anteromedial, cls – clypeal, des – dorsal epicranial, dms – dorsal malar, fs – frontal epicranial, les – lateral epicranial, ligs – ligular, lms – labral, mds – mandibular dorsal, mpxs – maxillary palps, pes – postepicranial, pfs – palpiferal, pms – postmental, prms – premental, stps – stipital, ves – ventral, vms – ventral malar.

Antennae membranous and distinctly convex basal membranous article bearing one relatively long conical sensorium and four sensilla basiconica (Fig. 22B).

Clypeus (Fig. 22C) ~ 3–4× as wide as long with two relatively long cls, located posterolaterally, without sensillum; fused to labrum.

Mouth parts. Labrum (Fig. 22C) ~ 4× as wide as long, with three piliform lms, relatively long, almost of equal length; lms₁ located anteromedially, lms₂ partly located close to clypeus, and lms₃ located anterolaterally. Epipharynx (Fig. 22D) with two very long digitate als, almost identical in length; with three ams of different length, ams₁ and ams₂ piliform and short, digitate ams₃ and enlarged in middle; without mes; labral rods indistinct, irregular in shape. Mandibles (Fig. 22E) with two relatively long, piliform mds, located in distinct holes. Maxilla (Fig. 22F): stipes with one stps, two pfs and without mbs and sensillum, stps and pfs₁ long, pfs₂ relatively long; mala with four short digitate dms; three vms, different lengths, one seta very short, and two setae minute. Maxillary palpi with two palpomeres; length ratio of basal and distal palpomeres: 1:0.5. Praelabium (Fig. 22F) oval, with one long prms; ligula with sinuate margin and two very short ligs; premental sclerite broad, well visible. Postlabium (Fig. 22F) with two pms, pms₁ absent, short pms₂ located laterally and very long pms₃ located medially; membranous area sparsely and finely asperate.

Thorax. Prothorax (Fig. 23A) with six long and two very short to minute prns, small pigmented dorsal sclerite present with two long prns, this sclerite subdivided into two triangular plates medially; two long ps; and two short to very short eus. Mesothorax (Fig. 23A) with two very short to minute prs, two long pds; one long as; one long and two very short to minute ss; one long eps; one long ps; and two short eus. Chaetotaxy of metathorax (Fig. 23A) almost identical to that of mesothorax. Each pedal area of thoracic segments well separated, with three long and one very short to minute pda.

Figure 23. 

Gymnetron villosulum Gyllenhal mature larva, habitus A lateral view of thoracic segments B lateral view of abdominal segment I C lateral view of abdominal segments VI–X. Abbreviations: Th1–3 – numbers of thoracic segments, Ab1–10 – numbers of abdominal segments; 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, ts – terminal.

Abdomen. Spiracles on abdominal segments I–VI close to the anterior margin and functional, spiracles on abdominal segment VII not functional, and abdominal segment VIII with atrophied spiracles. Abdominal segments I–VI (Fig. 23B, C) with one short and one minute prs; one long pds; one long and one very short to minute ss; one long eps; one relatively long ps; one short lsts; and two very short and sometimes one additional minute eus. Abdominal segments VII–VIII (Fig. 23C) with one very short prs; one long pds; one long and one very short to minute ss; one long eps; one relatively long ps; one short lsts; and two very short and sometimes one additional minute eus. Abdominal segment IX (Fig. 23C) with one relatively long ds; two relatively long ps; and one short to very short sts. Abdominal segment X (Fig. 23C) with one very short seta (ts).

(Figs 24A–C, 25A–C). Measurements (in mm). Body length: 2.24–2.73. Body width: 1.30–1.55. Thorax width: 0.82–0.88.

Figure 24. 

Gymnetron villosulum Gyllenhal pupa habitus A ventral view B dorsal view. Scale bars: 1 mm.

Body. Brownish, pronotal protuberances (p-pr) sclerotized, smooth; head, rostrum and pronotum darker than rest of body. Rostrum moderately slender. Pronotal protuberances fused at basis. Pronotum 2.2× as wide as long. Mesonotum distinctly smaller than metanotum. Urogomphi short, conical, with sclerotized apices. Abdominal segment VIII with rounded, prominent abdominal protuberance dorsally (Fig. 25A, B).

Figure 25. 

Gymnetron villosulum Gyllenhal pupa habitus A ventral view B dorsal view C lateral view. Abbreviations: a–pr – abdominal 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.

Chaetotaxy. Sparse, setae short to medium, transparent. Head with one medium os. Rostrum with one rs (Fig. 25A). Pronotum with one elongate as, one ls, and four pls all almost equal in length. Dorsal parts of meso- and metathorax with two setae of various length, placed medially. Apices of femora with one medium-sized fes (Fig. 25A–C). Abdominal segments I–VIII with two medium-sized setae (one placed medially, the other laterally). Each lateral part of abdominal segments I–VIII with one medium-sized seta. Ventral parts of abdominal segments I–VIII with two medium-sized setae. Abdominal segment IX with two minute setae ventrally (Fig. 25A–C).

The host plants of this species are several Veronica species: V. anagallis-aquatica L., V. anagalloides Guss., V. beccabunga L., V. catenata Pennell, V. scutellata L. (Kleine 1910; Urban 1930; Hustache 1931; Hoffmann 1958; Sprick 1997). The adults appear on the host plants in May. The females oviposit during June in the ovarial tissue, inducing a bulbous gall in which the larva develops.

This species is common in the whole of Europe and Anatolia. The adult is closely related to G. miyoshii, a vicariant species living in eastern Asia (Caldara 2008a; Alonso-Zarazaga et al. 2017). The immature stages confirm this relationship, as they share the postdorsal segment on the abdominal segments with one pds and the dorsal epicranium without des₄.