Sibinia femoralis Germar, 1824

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 : 159-163

Sibinia femoralis Germar, 1824

Caldara, 1985: 45.

Material examined. 17 larvae from seeds of Silene sericea All. collected 18.v.1979 at the mouth of the river Posada (Nuoro province, Sardinia), leg. R. Caldara, and 16 (9 ♂♂, 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: 0.55–0.63 mm (see Table. 1). Endocarinal line present, distinctly reaching middle of frons. Des1 very short, located almost in central parts of epicarnium; des2 absent; des3 long, located along frontal suture; des4 absent; des5 long, located anterolaterally ( Fig. 16 ). Fs1 and fs2 absent; fs3 very short, located medially; fs4 moderately long, located anteromedially (along epistoma); fs5 long, located anterolaterally (along epistoma) ( Fig. 16 ). Les almost as long as des3; both ves short. Postepicranial area without pes and with 2 sensilla. Antennal segment membranous, bearing conical sensorium and 2 very short, conical, sensilla ( Fig. 19 ).

Clypeus ( Fig. 20 ) 3.5 times as wide as long; without setae, and 1 sensillum, all located posterolaterally; anterior margin slightly rounded inside. Labrum ( Fig. 20 ) approximately 2.3 times as wide as long; lms1 distinctly shorter than lms2, and as long as lms3; anterior margin slightly sinuate. Epipharynx ( Fig. 21 ) with 2 finger-like als, equal in length; with 3 short ams, ams1 as long as ams2; with 2 relatively short and finger-like mes (see comments about ams and mes in Material and Methods); labral rods short, kidney-shaped, strongly converging posteriorly.

Mandibles ( Fig. 18 ) with 1 short mds. Maxilla ( Fig. 17 ): 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, similar in length; with 3 short vms, almost of equal length. Maxillary palpi: length ratio of basal and distal palpomeres 1:1.5; basal palpomera with 1 short mxps; distal palpomera with group of 3–4 conical, cuticular apical processes. Prementum ( Fig. 17 ) almost rounded, with 1 prms; margin of ligula slightly curved inside; ligula with 2 short ligs; premental sclerite clearly visible. Postmentum ( Fig. 17 ) with 2 pms, pms1 absent, long pms2, 3 times as long as pms3.

THORAX AND ABDOMEN. Body length 3.50–4.50 mm (see Table. 1), elongate ( Fig. 22 ). Abdominal segments I– V almost equal in length, slightly larger than abdominal segment VI and VII ( Fig. 22 ). Spiracles on abdomen in median parts of segments (abdominal seg. I–VIII).

Chaetotaxy of body rather reduced. Setae moderately long to very short and light yellow. Thorax. Prothorax ( Fig. 23 ) with 7 prn, 6 macro- and 1 microsetae; 2 moderately short ps of same length; 1 moderately short eus. Meso- and metathorax ( Fig. 23 ) with 1 short prs; 2 short pds, almost similar in length; alar area with 1 short as; 1 short ss (mesothorax without ss); 1 moderately short eps; 2 ps, similar in length; and 1 short eus. Each pedal area of thoracic segments well-separated and with 2–4 moderately long pda. Abdomen. Abdominal segments I–VII ( Figs. 24, 25 ) with 1 moderately long prs; 3 short pds of similar length, pds1 and pds3 shorter than pds2; 2 ss of different length, ss1 very short to minute, ss2 moderately long; 2 short eps in equal length; 2 ps of similar length, ps1 short and ps2 moderately long; 1 moderately long lsts; and 2 moderately long to short eus. Abdominal segment VIII ( Fig. 25 ) with 1 moderately long prs; 3 moderately short pds of similar length, pds1 and pds3 shorter than pds2; 1 very short ss; 2 moderately short eps in equal length; 2 short ps; 1 moderately short lsts; and 2 short eus. Abdominal segment IX ( Fig. 25 ) with 2 short ds of similar length; 1 moderately short ps; and 2 short sts in equal length. Anal lobes on abdominal segment X ( Fig. 25 ) without setae.

Description of pupa. COLORATION. Body yellow.

MORPHOLOGY ( Figs. 26–30 ). Body length 2.80–3.30 mm; widest part 1.25–2.00 mm (see Table. 2 ). Body rather stout. Rostrum long, approximately 6 times as long as wide, reaching over mesocoxae. Pronotum 1.65 times as wide as long.

CHAETOTAXY ( Figs. 26–30 ). Setae distinct, short, unequal in length, light brown or brown, almost as thornlike. Pas and rs distinctly shorter than other setae of head and rostrum ( Fig. 27 ). Ds2 distinctly shorter than other setae on pronotum ( Fig. 29 ). Setae on abdominal segments I–VIII placed posteromedially and posterolaterally; all abdominal setae located on thorn-like protuberances, short, curved. Pseudocerci short, conical, curved to inside.

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

Remarks. This is a common species with a wide Euro-Asiatic distribution that was reported to live on several species belonging to the genus Silene ( S. colorata Poiret , S. conica L., S. niceaensis All. , S. otites (L.) Wib., S. portensis L., S. pseudatocion Desf. , S. reflexa Ait. , and S. sericea All. : Hoffmann 1955; Scherf 1964; Caldara 1985). Adults are variable primarily in the pattern and color of the dorsal vestiture, with the consequence of the description of many different species and varieties in the past ( Caldara 1985).

Figures

FIGURES 16 – 21. Sibinia femoralis mature larva head, antenna and mouth parts: 16 — dorsal view (des — dorsal epicranial s., fs — frontal epicranial s., les — lateral epicranial s., ves — ventro epicranial s., at—antenna); 17 — 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.); 18 — right mandible (mds — mandible dorsal s.); 19 — antenna; 20 — labrum and clypeus (lms — labral s.); 21 — epipharynx (ams — anteromedial s., als — anterolateral s., mes — median s., lr—labral rods).

FIGURES 22 – 25. Sibinia femoralis mature larva habitus: 22 — lateral view, 23 — lateral view of thoracic segments, 24 — lateral view of abdominal segment I, 25 — 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 26 – 30. Sibinia femoralis pupa habitus: 26 — ventral view; 27 — detail of head; 28 — dorsal view; 29 — detail of pronotum; 30 — 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).