Otiorhynchus

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 : 23-26

Otiorhynchus (s. str.) armadillo (Rossi, 1792)

Material examined: 28 larvae ( Figs. 210 , 231 ). Larvae were obtained from permanent breeding in the climate chamber of the JKI, Braunschweig, continued until today and started in 2010 with first instar larvae from Thorsten Ufer, Ellerhoop. On 12.07.2010, 0 9.08.2010 and 12.09.2010 first instar larvae from adults collected in Mühlacker (on 17.06.2010) were placed mainly in flowerpots with Euonymus fortunei cultivar ‘Emerald ‘n Gold’ ( Fig. 221 ), and also with a cultivar of Bergenia cordifolia and with Primula veris L. Since June 2011 only different cultivars of Euonymus fortunei were used. In flowerpots with first instar larvae from 12.09.2010 the first teneral adult specimen was seen on 0 3.01.2011. The following larvae were used for the description: JKI, Braunschweig, breeding with Primula veris , 16.11.2010, 1 ex.; JKI, permanent breeding with Euonymus fortunei , 21.09.2011, 10 ex.; dto., 28.10.2011, 1 ex.; dto., 0 5.01.2012, 6 ex.; dto., 10.01.2013, 5 ex.; Ellerhoop, breeding by Thorsten Ufer with Euonymus fortunei flowerpots, received on 0 3.01.2011, 5 ex., from plants used for efficacy tests of entomopathogenous nematodes.

Remarks about breeding and development. The life-cycle of this species was studied for the first time by Del Bene & Parrini (1986), but together with Otiorhynchus sulcatus , as preimaginal instars could not be distinguished. This paper contains a long list of ornamental plants from 25 families on which O. armadillo was found, exclusively woody plants including some conifers. According to Del Bene & Parrini (1986) eggs from both species were deposited from June to September, larvae were present from August during the whole winter until April, then pupation occurred from April to end of May, followed by the presence of adults from May to September. Our results for O. armadillo are not completely in accordance with these life-cycle data. There were also overwintering adults already in April, e.g. on Thuja and other bushes. Pupae were found from end of April until end of July and newly hatched adults from mid-May or June until September, which may indicate pupation at least until August. Usually recently emerged adults of O. armadillo were found up 2 to 3 weeks later than the last teneral adults of O. sulcatus (Sprick 2012, in Sprick & Stüben 2012). Apparently, the life-cycle of O. armadillo is very similar to that of O. sulcatus , but should be studied at further sites to complete and validate the data.

Description ( Figs. 56–66 ).

Coloration. Head light yellow; all thoracic and abdominal segments milk-white, cuticle smooth.

Body elongated ( Fig. 56 ). Chaetotaxy. Setae different in length, relatively long, filiform, light yellowish. Thorax. Prothorax with 4 long and 4 medium long to short prns; and 2 ps, different in length. Mesothorax with 1 medium long prs; 4 pds (ordered: 2 short and 2 long); 1 long as; 1 long eps; and 1 long ps. Chaetotaxy of meso- and metathorax similar. Each pedal area of thoracic segments well isolated, with 4 pda, different in length. Each thoracic segment with 1 short eus ( Fig. 57 ). Abdomen. Abdominal segments I–VIII with 1 short prs; 5 pds (ordered: 2 short, 1 long, 1 short and 1 long); 1 long sps [abd. seg. VIII without sps]; 2 long eps; 1 long and 1 minute ps [abd. seg. VIII with only 1 long ps]; 1 long lsts; and 2 eus ( Figs. 58, 60, 61 ). Abdominal segment IX with 4 ds, different in length; 1 very long ps; and 2 sts, equal in length ( Figs. 59–61 ). Lateral lobes of abdominal segment X without seta.

Head subglobose, slightly narrowed bilaterally ( Fig. 62 ). Head capsule with 4 des, des 1 and des 2 placed on central part of epicranium, des 3 located on frontal suture, des 5 located anterolaterally; 2 fs, fs 4 placed anteromedially, fs 5 located near to antenna; 2 les and 1 ves; all setae relatively long with the exception of fs 4, which is distinctly shorter than the others. Stemmata (2 pairs) very small, feebly visible. Antennal segment membranous, bearing 1 conical sensorium and 2–3 filiform sensilla. Clypeus 2.8 times as wide as long with 1 very short cls, placed posterolaterally ( Fig. 63 ). Labrum about 2 times as wide as long with 3 straight lms of different length, placed medially or mediolaterally; lms 2 distinctly longer than other setae, only lms2 exceeding the outline of the labrum; the anterior margin of labrum almost rounded ( Fig. 63 ). Epipharynx with 3 finger-like als, different in length; 3 ams, different in length, one very small ams similar to mes, but the position is more to ams; and 2 very short mes (see comments about ams and mes in Material and Methods); labral rods (lr) elongated, strong convergent ( Fig. 64 ). Mandible ( Fig. 65 ) feebly bifid, teeth almost of equal height; with 2 mds, different in length; internal edge with a triangular tooth. Maxilla ( Fig. 66 ) with 1 very long stps and 2 very long pfs, placed ventrolaterally; 1 very short mbs, situated ventrally. Mala with 5 dms, different in length and 4 straight vms, different in length. Maxillary palpi with two palpomeres; basal palpomere larger than distal; basal palpomere with 1 mxps; distal palpomere with a group of 5 conical, cuticular processes apically; each palpomere with a sensillum. Praelabium heart-shaped ( Fig. 66 ), with 2 very short ligs and 1 very 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 times as long as pms 1 and pms 3 ( Fig. 66 ).

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 220 – 225. Breeding and collecting of the weevil larvae. 220, 222 — Sampling sites of O. crataegi under Taxus in Bad Zwischenahn, 221 — Breeding of O. armadillo in flowerpots with Euonymus fortunei cultivar Emerald ' n Gold, 223, 225 — Sampling sites of O. rugosostriatus under Panicum virgatum in Wiesbaden-Schierstein, 224 — Breeding of O. aurifer in a flowerpot with Viburnum tinus. (Photos by P. Sprick).

FIGURES 56 – 61. Otiorhynchus armadillo; mature larva. 56 — habitus, lateral view, 57 — lateral view of thoracic segments, 58 — lateral view of abdominal segment I, 59 — lateral view of abdominal segments VIII – IX, 60 — ventral view of abdominal segments VIII – X, 61 — 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.

FIGURES 62 – 66. Otiorhynchus armadillo; mature larva and mouthparts. 62 — dorsal view of head, 63 — labrum and clypeus, 64 — epipharynx, 65 — left mandible, 66 — 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.