Tychius (s. str.) schneideri (Herbst, 1795)

Skuhrovec, Jiří, Gosik, Rafał & Caldara, Roberto, 2014, Immatures of Palaearctic species of the weevil genus Tychius (Coleoptera, Curculionidae): new descriptions and new bionomic data with an evaluation of their value in a phylogenetic reconstruction of the genus, Zootaxa 3839 (1), pp. 1-83 : 13-14

Tychius (s. str.) schneideri (Herbst, 1795)

Caldara, 1990: 158.

Material examined. 13 larvae from pods of Anthyllis vulneraria polyphilla (DC.) Nyman collected 25.vi.1981 at Bobbio , Piacenza province , Emilia (northern Italy), leg. R. Caldara, and 14 pupae obtained from larvae collected similarly to the others, all determined by association with reared adults.

Differential diagnosis. See Tables 2 and 3 .

Description of mature larva. COLORATION. Head brown. All thoracic and abdominal segments white to whitish yellow.

HEAD CAPSULE AND MOUTH PARTS. Head width: 0.40–0.46 mm (see Table. 1 ). Endocarinal line present, reaching middle of frons. Des 1 located almost in central parts of epicarnium; des 2 located very near frontal suture, near des 3; des 3 located along frontal suture; des 4 absent; des 5 located anterolaterally; des 2 4 times shorter than others (des 1, des 3, des 5) ( Fig. 73 ). Fs 1 and fs 2 absent; fs 3 short, located posteromedially; fs 4 located anteromedially (along epistoma); fs 5 located anterolaterally (along epistoma), 3 to 4 times longer than fs 3 ( Fig. 73 ). Les distinctly shorter than des 3. Ves 1–2 very short. Post-epicranial area with 1 minute pes. Antennal segment membranous, bearing conical sensorium and 5 very short, conical, sensilla ( Fig. 76 ).

Labrum ( Fig. 77 ) approximately 3 times as wide as long; lms 1 2 times longer than lms 3, lms 2 some shorter than lms 1; anterior margin rounded. Clypeus ( Fig. 77 ) 2.4 times as wide as long. with 2 pairs of very short cls of same length, and 1 sensillum, all located posterolaterally; anterior margin slightly rounded inside. Epipharynx ( Fig. 78 ) with 2 pairs of als, different in length; with 2 pairs of short and triangular ams; with 2 moderately long finger-like and 1 short mes; labral rods short, kidney-shaped, almost parallel. Mandibles ( Fig. 75 ) with 2 short mds, almost of equal length. Maxilla ( Fig. 74 ): stipes with 1 stps, and with 2 pfs of different length; with 4 slightly curved dms, different in length; with 2 vms, short and almost of equal length. Maxillary palpi: length ratio of basal and distal palpomeres 1:0.7; basal palpomera with 1 short mpxs; distal palpomera with group of 2–3 conical, cuticular apical processes. Prementum ( Fig. 74 ) heart-shaped, with 1 prms; margin of ligula rounded; ligula with 1 lig; premental sclerite distinct. Postmentum ( Fig. 74 ) with 3 pairs of pms, different in length.

THORAX AND ABDOMEN. Body length 2.3–3.2 mm (see Table. 1 ), elongate ( Fig. 79 ). Abdominal segments I–V almost equal in length, slightly larger than abdominal segment VI and VII ( Fig. 79 ). Spiracles on abdomen in median parts of segments (abdominal seg. I–VIII).

Chaetotaxy of body rather reduced. Setae moderately long or short and light yellow. Thorax. Prothorax ( Fig. 80 ) with 8 prn, 7 macro- and 1 microsetae; 2 moderately long ps of same length; 1 eus. Meso- and metathorax ( Fig. 80 ) with 2 prs, different in length; 3 pds, different in length; alar area with 1 very short as; 1 very short ss; 1 eps; 1 ps; and 1 short eus. Each pedal area of thoracic segments well-separated and with 2 pda. Abdomen. Abdominal segments I–VII ( Fig. 81 ) with 1 prs; 3 pds of different length; 2 ss of different length; 1 eps; 2 ps of different length; 1 lsts; and 2 eus. Abdominal segment VIII ( Fig. 82 ) with 2 pds of different length; 2 ss of different length; 1 eps; 2 ps of different length; 1 lsts; and 2 moderately long eus. Abdominal segment IX ( Fig. 82 ) with 2 ds of different length; 1 ps; and 1 sts. Anal lobes on abdominal segment X ( Fig. 82 ) with 2 very short, feebly visible setae.

Description of pupa. COLORATION. Body whitish yellow.

MORPHOLOGY ( Figs. 83–85 ). Body length 2.0– 2.7 mm; widest part 1.2–1.5 mm (see Table. 1 ). Body elongate. Rostrum long, approximately 4.5 times as long as wide, reaching mesocoxae. Pronotum 1.9 times as wide as long.

CHAETOTAXY ( Figs. 83–85 ). Setae distinct, moderately long, unequal in length, light brown; on pronotum and head placed on conical protuberances. Head capsule including 1 vs, 1 os, and 1 pas. Rostrum with 1 rs located medially. Vs and os as long as setae on pronotum, distinctly longer than pas and rs. Pronotum with 2 as, 2 ls, 2 ds, and 1 pls; ds as long as other setae on pronotum. Dorsal parts of meso- and metathorax with 1 seta. Each apex of femora without seta. Setae on abdominal segments I–VIII placed posteromedially and posterolaterally; all abdominal setae located on small, conical protuberances. Pseudocerci short, slightly curved inside.

Biological observations. Pupation was observed 15 days after the introduction of the larvae in the soil. The duration of the pupal stage was about 12 days. Adults began to emerge from the cells 7 days later.

Remarks. Tychius schneideri is monophagous on Anthyllis vulneraria L. s. l. and is widely distributed in Europe. The larva was described, although incompletely, by Karasyov (1991) on specimens collected at Minsk ( Bielorussia).

Figures

FIGURES 73–78. Tychius schneideri mature larva head, antenna and mouth parts: 73—dorsal view (des—dorsal epicranial s., fs—frontal epicranial s., les—lateral epicranial s., ves—ventral epicranial s., pes—posterior epicranial s., st—stemmata, at—antenna); 74—right maxilla, dorsal view (dms—dorsal malar s., vms—ventral malar s., mpxs—maxillary palps s., pfs—palpiferal s., stps—stipital s.), prementum and postmentum, ventral view (prms—premental s., pms—postmental s., ligs—ligular s.); 75—right mandible (mds—mandible dorsal s.); 76—antenna; 77—labrum and clypeus (cls—clypeal s., lms—labral s.); 78—epipharynx (ams—anteromedial s., als—anteriolateral s., mes—median s., lr—labral rods).

FIGURES 79–82. Tychius schneideri mature larva habitus: 79—lateral view, 80—lateral view of thoracic segments, 81—lateral view of abdominal segment I., 82—lateral view of abdominal segments VIII–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.).

FIGURES 83–85. Tychius schneideri pupa habitus: 83—ventral view, 84—dorsal view, 85—lateral view (vs—vertical s., os—orbital s., pas—postantennal s., rs—rostral s., as—apical s., ls—lateral s., ds—discal s., pls—posterolateral s., pc—pseudocerci).