Otiorhynchus (Nehrodistus) armatus Boheman, 1846

Rafał Gosik, Peter Sprick, Jiří Skuhrovec, Magdalena Deruś & Martin Hommes, 2016, Morphology and identification of the mature larvae of several species of the genus Otiorhynchus (Coleoptera, Curculionidae, Entiminae) from Central Europe with an update of the life history traits, Zootaxa 4108 (1), pp. 1-67 : 20-23

Otiorhynchus (Nehrodistus) armatus Boheman, 1846

Material examined: 61 larvae ( Figs. 209 , 230 ). JKI, Braunschweig, climate chamber, Chaenomeles x superba cultivar ‘Hollandia’, flowerpot, 0 4.10.2013, 7 ex.; dto., Euonymus fortunei , 25.09.2014, 6 ex.; dto., Euonymus fortunei , 0 7.10.2014, 6 ex.; dto., Hedera helix L., 0 7.10.2014, 26 ex.; and 25.09.2014, 13 ex.; dto., Prunus laurocerasus cultivar ‘Van Nes’, 19.12.2013, 3 ex.

Remarks about breeding and development. The larvae of this species were obtained from two breeding attempts in the JKI in 2013 and 2014. Otiorhynchus armatus is apparently easy to breed also in small flowerpots, and it accepted all tested plants ( Chaenomeles x superba, Euonymus fortunei , Hedera helix , Prunus laurocerasus ). During the past 15 years this taxon as well as the closely related or even identical O. corruptor (Host, 1789) was introduced several times to Germany and became noxious in indoor greeneries. Up to now, no permanent population (of both taxa) is known from Germany.

All adults had been collected by Klaus Schrameyer in Merano / Northern Italy on 18.05.2013, in the town from a hotel wall with ivy ( Hedera helix ). The weevils were not sclerotized, young adults at this point in time. 4 males and 3 females were used for the first breeding attempt (released on the plants on 24.05.2013) and 8 specimens of undetermined sex for the second (started on 24.06.2014). Adults and larvae from 2014 represent the second reared generation. Breeding gave no indication for any diapause. Mature larvae were already obtained in September and October, and pupae in November and December.

The life-cycle of this species is apparently unknown, but seems to be in some kind resembling to that of Otiorhynchus sulcatus : emergence of newly hatched adults from (approximately) mid-May, larval development within a few months, pupation during the whole season if temperature remains high in autumn and winter, development also in small flowerpots. The most striking difference is—in Central Europe—the much stronger limitation to indoor situations, apparently due to the demand of higher temperatures. Viggiani (1977) reports about damage on Fragaria and an occurrence on Vitis vinifera L., Ficus carica L., Hedera helix , Spiraea apulifolia L. and Citrus medica L. in Campania ( Italy).

Description ( Figs. 45–55 ).

Coloration. Head yellow; all thoracic and abdominal segments white; except brownish pronotum; cuticle almost smooth, microcuticular processes, brown, poorly visible.

Body moderately elongated ( Fig. 45 ). Chaetotaxy. Setae different in length, filiform; brown. Thorax. Prothorax with 4 long and 4 medium long to short prns; and 2 ps, different in length. Mesothorax with 1 short prs; 4 pds (ordered: 1 short, 1 medium long and 2 long); 1 long as; 1 long eps; and 1 long ps. Chaetotaxy of meso- and metathorax similar, with the exception of pds on metathorax (ordered: 1 short, 1 long, 1 medium long and 1 long). Each pedal area of thoracic segments well isolated, with 5 pda, different in length. Each thoracic segment with 1 short eus ( Fig. 46 ). Abdomen. Abdominal segments I–VIII with 1 short prs; 5 pds (ordered: 2 short, 1 long, 1 short and 1 long); 1 long and 1 minute sps [abd. seg. VIII with only 4 pds (1 long, 1 short, 1 long and 1 short) and 1 minute sps]; 2 eps, different in length; 1 long and 1 minute ps; 1 long lsts; and 2 eus ( Figs. 47, 49, 50 ). Abdominal segment IX with 3 ds, different in length; 2 ps, different in length; and 2 sts, equal in length ( Figs. 48–50 ). Each lateral lobe of abdominal segment X with 2–3 minute ts.

Head subglobose, narrowed bilaterally ( Fig. 51 ). Head capsule with 4 relatively short and 1 minute des, des 1 and des 2 placed on central part of epicranium, des 3 located on frontal suture, des 5 located anterolaterally, minute des 4 located close to stemmata, all des equal in length; 2 relatively short fs, fs 4 placed anteromedially, fs 5 located near to antenna; 2 relatively short les; and 1 very short ves. Postepicranial area with a group of 2 pairs of sensilla, frons with 2 pairs of sensilla. Stemmata (2 pairs) feebly visible. Antennal segment membranous, bearing 1 conical sensorium and 4 filiform sensilla. Clypeus 3.6 times as wide as long with 2 very short cls, equal in length, placed posterolaterally ( Fig. 52 ). Labrum about 1.7 times as wide as long with 3 straight lms of different length, placed medially or mediolaterally; lms 3 distinctly shorter than other setae, all lms exceeding the outline of labrum; anterior margin of labrum rounded ( Fig. 52 ). Epipharynx with 3 finger-like als, different in length; 2 ams, different in length; and 2 very short mes; labral rods (lr) short, reniform, strong convergent; epipharynx covered by nodular cuticular processes ( Fig. 53 ). Mandible ( Fig. 54 ) bifid, teeth almost of equal height; with 2 mds, different in length; internal egde with a triangular tooth. Maxilla ( Fig. 55 ) with 1 very long stps and 2 very long pfs, placed ventrolaterally; 1 very short mbs, situated ventrally. Mala with 6 dms, different in length and 3 straight vms, different in length. Maxillary palpi with two palpomeres; basal palpomere distinctly wider than distal; basal palpomere with 1 mxps; distal palpomere with a group of 6 conical, cuticular processes apically; each palpomere with a sensillum. Praelabium heart-shaped ( Fig. 55 ), with 2 very short ligs and 1 long prms. Labial palpi with two palpomeres, relatively elongated; both palpomeres almost equal in length; praemental sclerite well visible. Postlabium with 3 pms, different in length; pms 2 very long, 3–4 times as long as pms 1, and 5 times as long as pms 3 ( Fig. 55 ).

Differential diagnosis. See “Key to larvae of selected Otiorhynchus species” and Tables 1, 2.

Figures

FIGURES 203 – 210. Mature larva, lateral view. 203 — O. indefinitus, 204 — O. raucus, 205 — O. ligustici, 206 — O. sulcatus, 207 — O. porcatus, 208 — O. singularis, 209 — O. armatus, 210 — O. armadillo. (Photos by R. Gosik).

FIGURES 226 – 231. Breeding and collecting of the weevil larvae. 226 — O. aurifer larvae from breeding in the climate chamber, 227 — O. crataegi larva and pupa in the field—size compared with a Taxus needle, 228 — O. rugosostriatus larva in the Panicum virgatum field in Wiesbaden-Schierstein, 229 — O. rugosostriatus, young adult, just hatched, found under Panicum virgatum, as before, 230 — O. armatus, 2 mature larvae on graph paper, 231 — O. armadillo larva in a flowerpot used for breeding. (Photos by P. Sprick).

FIGURES 45 – 50. Otiorhynchus armatus; mature larva. 45 — habitus, lateral view, 46 — lateral view of thoracic segments, 47 — lateral view of abdominal segment I, 48 — lateral view of abdominal segments VIII – IX, 49 — ventral view of abdominal segments VIII – X, 50 — dorsal view of abdominal segments VIII – X. Abbreviations: Ab. — abdominal segment, Th. — thoracic s., I – X—number of segments, prns — pronotal seta (e), prs — prodorsal s., pds — postdorsal s., pda — pedal s., as — alar s., lsts — laterosternal s., eus — eusternal s., ps — pleural s., sps — spiracular s., sts — sternal s., ds — dorsal s., ts — terminal s.

FIGURES 51 – 55. Otiorhynchus armatus; mature larva and mouthparts. 51 — dorsal view of head, 52 — labrum and clypeus, 53 — epipharynx, 54 — left mandible, 55 — maxillo-labial complex. Abbreviations: des — dorsoepicranial seta (e), fs — frontal s., les — lateroepicranial s., ves — ventroepicranial s., at—antenna, st—stemmata, cls — clypeal s., lms — labral s., ams — anteromedial s., als — anterolateral s., mes — medial s., lr—labral rods, mds — mandible dorsal s., dms — dorsal malae s., vms — ventral malae s., mxps — maxillary palps s., pfs — palpiferal s., stps — stipal s., mbs — mandible basiventral s., prms — prelabial s., pms — postlabial s., ligs — ligular s.