Sibinia viscariae (Linnaeus, 1760)

Skuhrovec, Jiří, Gosik, Rafał, Caldara, Roberto & Košťál, Michael, 2015, Immatures of Palaearctic species of the weevil genus Sibinia (Coleoptera, Curculionidae): new descriptions and new bionomic data with suggestions on their potential value in a phylogenetic reconstruction of the genus, Zootaxa 2, pp. 151-187 : 170-172

Sibinia viscariae (Linnaeus, 1760)

Caldara, 1985: 33.

Material examined. 31 larvae from seeds of Silene vulgaris (Moench) collected 3.vii.1982 at Levanto (Liguria, northern Italy), leg. R. Caldara, and 12 (5 ♂♂, 7 ♀♀) pupae obtained from larvae collected similarly to the others, all determined by association with reared adults.

Differential diagnosis. See Key to the immatures of the Palaearctic species of the genus Sibinia and Table. 3 .

Description of mature larva. COLORATION. Head brown to dark yellow. All thoracic and abdominal segments light yellow.

HEAD CAPSULE AND MOUTH PARTS. Head width: 0.68–0.75 mm (see Table. 1). Endocarinal line present, reaching middle of frons. Des1 very short, located near frontal suture; des2 very short, located almost in central parts of epicarnium; des3 long, located along frontal suture; des4 absent; des5 long, located anterolaterally ( Fig. 46 ). Fs1 and fs2 absent; fs3 minute, located medially; fs4 long, located anteromedially (along epistoma); fs5 very long, located anterolaterally (along epistoma), fs5 2.5 times as long as fs4 ( Fig. 46 ). Les almost as long as des3; both ves short. Postepicranial area with 1 pes and with 3 sensilla. Antennal segment membranous, bearing conical sensorium and 2 very short, conical, sensilla ( Fig. 49 ).

Clypeus ( Fig. 50 ) 3 times as wide as long; without setae, and 1 sensillum, all located posterolaterally; anterior margin slightly rounded inside. Labrum ( Fig. 50 ) approximately 3.5 times as wide as long; lms1 distinctly shorter than lms2, and as long as lms3; anterior margin slightly sinuate. Epipharynx ( Fig. 51 ) with 2 short, finger-like als, similar in length; with 3 short ams, similar in length; with 2 relatively short and finger-like mes (see comments about ams and mes in Material and Methods); labral rods elongate, kidney-shaped, strongly converging posteriorly. Mandibles ( Fig. 48 ) with 1 moderately long mds. Maxilla ( Fig. 47 ): stipes with 1 long stps, and with 2 long pfs, pfs1 1.5 times as long as pfs2; 1 very short mbs; mala with 4 slightly curved dms, different in length; with 3 very short vms, almost of equal length. Maxillary palpi: length ratio of basal and distal palpomeres 1:1.7; basal palpomera with 1 short mxps; distal palpomera with group of 3–4 conical, cuticular apical processes. Prementum ( Fig. 47 ) almost rounded, with 1 prms; margin of ligula slightly curved inside; ligula with 2 ligs; premental sclerite clearly visible. Postmentum ( Fig. 47 ) with 2 pms, pms1 absent, long pms2, 2.5 times as long as pms3.

THORAX AND ABDOMEN. Body length 4.20–5.30 mm (see Table. 1), elongate ( Fig. 52 ). Abdominal segments I– V almost equal in length, slightly larger than abdominal segment VI and VII ( Fig. 52 ). Spiracles on abdomen in median parts of segments (abdominal seg. I–VIII).

Chaetotaxy of body rather reduced. Setae long to very short and light yellow. Thorax. Prothorax ( Fig. 53 ) with 9 prn, 8 macro- and 1 microsetae; 2 moderately long ps of same length; 1 moderately short eus. Meso- and metathorax ( Fig. 53 ) with 1 long prs; 2 long pds, different in length; alar area with moderately long 1 as; 1 long ss (mesothorax with very short ss); 1 moderately long eps; 2 moderately long ps; and 1 moderately short eus. Each pedal area of thoracic segments well-separated and with 2–4 pda. Abdomen. Abdominal segments I–VII ( Figs. 54, 55 ) with 1 moderately long prs; 3 pds of different length, pds1 and pds3 very short to short, pds2 long; 2 ss of different length, ss1 very short, ss2 moderately long; 2 moderately long eps in equal length; 2 ps of different length, ps1 short and ps2 moderately long; 1 moderately long lsts; and 2 short eus. Abdominal segment VIII ( Fig. 55 ) with 1 moderately long prs; 3 pds of different length, pds1 and pds3 short, pds2 moderately long; 2 ss of different length, ss1 minute, ss2 moderately long; 2 moderately long eps in equal length; 2 ps of different length, ps1 short and ps2 moderately long; 1 moderately long lsts; and 2 very short eus. Abdominal segment IX ( Fig. 55 ) with 2 long ds; 2 ps of different length, ps1 short and ps2 moderately long; and 2 moderately long sts in equal length. Anal lobes on abdominal segment X ( Fig. 55 ) without setae.

Description of pupa. COLORATION. Body yellow.

MORPHOLOGY ( Figs. 56–60 ). Body length 2.95–3.90 mm; widest part 1.90–2.40 mm (see Table. 2 ). Body moderately stout. Rostrum long, approximately 5 times as long as wide, reaching mesocoxae. Pronotum 1.85 times as wide as long.

CHAETOTAXY ( Figs. 56–60 ). Setae distinct, short to moderately long, unequal in length, light brown, on head, rostrum and thorax hair-like, on abdomen almost as thorn-like. Sos and pas slightly shorter than other setae of head and rostrum ( Fig. 57 ). All pronotal setae moderately long and equal in length ( Fig. 59 ). Setae on abdominal segments I–VIII located posteromedially and posterolaterally; all abdominal setae short, curved, located on thornlike protuberances. Pseudocerci elongated, slightly curved to inside.

Biological observations. The larvae fed on seeds, and mature larvae left the capsule and entered the soil to pupate. Pupation was observed 10 days after the larvae entered the soil. Adults were found in the cells 9 days later.

Remarks. This common species with a wide Euro-Asiatic distribution was reported to live on several species belonging to the genera Silene ( S. dioica L., S. nutans L., and S. vulgaris L.) and Lychnis ( L. viscaria L.: Hoffmann 1955; Caldara 1985; Dieckmann 1988; Rheinheimer & Hassler 2010). The larva and the pupa were described synthetically by Scherf (1964), who reported on only length and coloration of the body, without comments on chaetotaxy.

Figures

FIGURES 46 – 51. Sibinia viscariae mature larva head, antenna and mouth parts: 46 — dorsal view (des — dorsal epicranial s., fs — frontal epicranial s., les — lateral epicranial s., ves — ventro epicranial s., st—stemmata, at—antenna); 47 — right maxilla, dorsal view (dms — dorsal malar s., vms — ventral malar s., mpxs — maxillary palps s., mbs — basioventral s., pfs — palpiferal s., stps — stipital s.), prementum and postmentum, ventral view (prms — premental s., pms — postmental s., ligs — ligular s.); 48 — right mandible (mds — mandible dorsal s.); 49 — antenna; 50 — labrum and clypeus (lms — labral s.); 51 — epipharynx (ams — anteromedial s., als — anterolateral s., mes — median s., lr—labral rods).

FIGURES 52 – 55. Sibinia viscariae mature larva habitus: 52 — lateral view, 53 — lateral view of thoracic segments, 54 — lateral view of abdominal segment I, 55 — lateral view of abdominal segments VII—X (prns — pronotal s., prs — prodorsal s., pds — postdorsal s., as — alar s., ss — spiracular s., eps — epipleural s., ps — pleural s., pda — pedal s., lsts — laterosternal s., eus — eusternal s., ds — dorsal s., sts — sternal s., Th 1 – 3 — number of thoracic segments, Ab 1 – 10 — number of abdominal seg.).

FIGURES 56 – 60. Sibinia viscariae pupa habitus: 56 — ventral view; 57 — detail of head; 58 — dorsal view; 59 — detail of pronotum; 60 — lateral view; (HW—head width; BW—body width; BL—body length; setae; as — apical s., d — dorsal s., ds — discal s., l — lateral s. on abdomen, ls — lateral s. on pronotum, os — orbital s., pas — postantennal s., pls — posterolateral s., sos — superorbital s., vs — vertical s.; pc—pseudocerci).