Mecinus janthinus Germar, 1821
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publication ID |
https://dx.doi.org/10.3897/zookeys.939.50612 |
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publication LSID |
lsid:zoobank.org:pub:B2397011-4888-4712-880E-1069C943AD33 |
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persistent identifier |
https://treatment.plazi.org/id/BFDC1297-8E5B-51C2-B7BE-0B190FD35FFE |
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treatment provided by |
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scientific name |
Mecinus janthinus Germar, 1821 |
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Mecinus janthinus Germar, 1821
Material examined.
9 L3 larvae and 8 pupae, Serbia, Mihajlovac, 5.07.2009, 44°21.541'N, 22°28.650'E, 130 m., ex L. vulgaris ; Serbia, Negotin, Tamnič, 2.08. 2007, 44°06.033'N, 22°30.105'E, 126 m., ex L. vulgaris ; 8 pupae, Serbia, Mihajlovac, 5.07.2009, 44°21.683'N, 22°28.697'E, 125 m., ex L. vulgaris ; 1 pupa, Serbia, DonjaKamenica, Kalna, 22.08.2011, 43°29.450'N, 22°19.712'E, 278 m., ex L. vulgaris . All collected by I. Toševski. Accession numbers of sequenced specimen MN992005.
Description of mature larva
(Figures 19A-D View Figure 19 , 20A-F View Figure 20 ). Measurements (in mm). Body length: 4.00-4.75. Body width (metathorax and abdominal segments I-II): 1.10-1.25. Head width: 0.50-0.57.
Body (Figure 19A-D View Figure 19 ) yellowish, very slender, densely covered with asperities. Prothorax smaller than meso- and metathorax. Abdominal segments I-V of almost equal length; segments VI-IX decreasing gradually to the terminal body part; segment X reduced to three anal lobes of those lateral are the largest, and dorsal the smallest (sometimes absent). Chaetotaxy well developed, setae capilliform, variable in length, greyish or yellow. Prothorax (Figure 19B View Figure 19 ) with eight long prns of equal length; two long ps and one short eus. Meso- and metathorax (Figure 19B View Figure 19 ) with one very short prs, three pds, variable in length (pds1 short, pds2-3 medium), one short as, three short ss, one long eps, one long ps and one long eus. Pedal area with five long pda. Abdominal segments I-VIII (Figure 19C, D View Figure 19 ) with one very short prs, four pds of different length (on segments I-V: pds1-2 short, pds3-4 long; on segments VI-VIII all pds very long, almost equal in length) and arranged along posterior margin; one minute and two medium ss, one short and one long eps, one long ps, one long lsts and two medium eus. Abdominal segment IX (Figure 19D View Figure 19 ) with four very long ds, all located close to the posterior margin, two long ps and two short sts. Each of lateral anal lobe with two minute setae.
Head capsule (Figures 19A View Figure 19 , 20A-F View Figure 20 ) yellow, distinctly narrowed bilaterally. Des1-3,5 very long, equal in length; des4 half the length of other des; des4 medially. Fs1,4,5 long, fs3 medium. Les1 and les2 long, equal in length; one ves, and four pes short (Figure 20A View Figure 20 ). Two stemmata of different size. Antennae (Figure 20B View Figure 20 ) with sensorium (Se) conical, twice as long as wide, and three sensilla of different types: one sa and two sb. Clypeus (Figure 20C View Figure 20 ) trapezium-shaped, anterior margin distinctly concave; two cls relatively long, located on protuberances; clss placed medially between cls. Labrum (Figure 20C View Figure 20 ) with sinuate anterior margin; lrs1-3 almost equal in length, all placed on protuberances. Epipharynx (Figure 20D View Figure 20 ) with three medium, finger-shaped als of almost equal length; two finger-like, different in length ams; two medium finger-like mes; surface smooth; labral rods close to kidney-shaped. Mandibles (Figure 20E View Figure 20 ) conical, wide, an elongated protuberance in the middle of the cutting edge; both mds capilliform, medium, equal in length, placed mediolaterally. Maxilla (Figure 20F View Figure 20 ) with one stps and two pfs of equal length; mbs medium; mala with six rod-like dms of almost equal size, five vms equal in length. Maxillary palpi: basal palpomere distinctly wider than distal, both of almost equal length. Prelabium (Figure 20F View Figure 20 ) cup-like with one very long prms; ligula with three medium ligs; premental sclerite clearly visible, cup-shaped. Labial palpi two-segmented; basal palpomere slightly wider and distinctly shorter than distal. Postlabium (Figure 20F View Figure 20 ) with three capilliform medium to long pms.
Description of pupa
(Figure 21A-C View Figure 21 ). Measurements (in mm). Head width: 0.46-0.56. Body width: 1.16-1.50. Body length: 3.70-4.05.
Body elongated, white. Rostrum slender, about 3.4 times as long as wide, reaching almost up to mesocoxae. Antennae slender and elongated. Pronotum 1.1 times as wide as long. Mesonotum slightly shorter than metanotum. Urogomphi (ur) slender and elongated, conical, with sclerotised apex, distinctly reaching outline of the body, directed outside (Figure 21A-C View Figure 21 ).
Chaetotaxy well developed, setae short or medium long. Head with one vs, two sos, two os and two pas. Rostrum with one rs placed medially. All setae of head equal in length (Figure 21A, B View Figure 21 ). Pronotum with two as, one ds, two sls, two ls, and three pls (Figure 21B, C View Figure 21 ). All setae on pronotum elongated, equal in length (Figure 21C View Figure 21 ). Dorsal parts of meso- and metathorax with two setae placed medially. Abdominal segments I-VIII with two setae laterally and three medium long setae ventrally. Dorsal parts of abdominal segments I-VII with six setae (d1 placed anteromedially, d2-4 placed posteromedially, d5-6 posterolaterally); segment VIII with five very long setae dorsally. Abdominal segment IX with two micro-setae ventrally.
Biological notes.
The host plant of M. janthinus is the yellow toadflax, Linaria vulgaris Mill. This species is distributed in temperate regions of the eastern Palearctic region, inhabiting lowlands and hilly slopes up to 500 m altitude. From beginning of the 1990s, M. janthinus was introduced as biological control agent for the control of invasive toadflaxes in North America ( Toševski et al. 2018). The adults emerge in early March and feed intensively on the newly growing shoots of the host plant. Oviposition occurs on actively growing shoots, and the preferred oviposition site is the widest part of the stem. Females lay one or, rarely, two eggs per shoot. This species is a true stem borer with larval feeding and mining in the central part of the stem. The adults overwinter in the stems of the host plant inside an elongated pupal chamber built by the last instar larva prior to pupation.
Remarks and comparative notes.
Mecinus janthinus is largely distributed in northern, central and southeastern Europe, Russia from the western borders to southern central Siberia, the Caucasian states, and Turkey. This species was introduced in North America for the biological control of toadflaxes in 1991-1999 ( Wilson et al. 2005). The adults can be easily confused with M. janthiniformis , both sympatric in part of their range of distribution, since the differences between them are few and subtle. In contrast, the larvae of these two species show numerous differences in the number of setae in many parts of the body, such as the head, antenna, pronotum and thoracic segments (see key).
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