Tychius (s. str.) brisouti Tournier, 1874

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 : 11-12

Tychius (s. str.) brisouti Tournier, 1874

Caldara 1990: 203; 1995b: 610.

Material examined. 29 larvae from pods of Astragalus monspessulanus L. collected 29.v.2008 at Castellar near Menton , Alpes-Maritimes (southern France), leg. R. Caldara, and 5 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 to dark brown. 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, exceeding 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 5 times shorter than des 3 and des 5 ( Fig. 47 ). Fs 1 and fs 2 absent; fs 3 short, located medially; fs 4 located anteromedially (along epistoma); fs 5 located anterolaterally (along epistoma), 4 times longer than fs 3 ( Fig. 47 ). Les distinctly shorter than des 3. Ves short. Post-epicranial area with group of 4 minute pes. Antennal segment membranous, bearing conical sensorium and 2 finger-like, sensilla ( Fig. 50 ).

Labrum ( Fig. 51 ) approximately 3 times as wide as long; lms 1 slightly longer than lms 2 and lms 3; anterior margin rounded. Clypeus ( Fig. 51 ) 3.9 times as wide as long; without setae; anterior margin slightly rounded inside. Epipharynx ( Fig. 52 ) with 2 pairs of als, almost of equal length; with 2 pairs of short ams, ams 2 distinctly shorter than ams 1; with 3 relatively short and finger-like mes; labral rods relatively long, elongate, slightly converging posteriorly. Mandibles ( Fig. 49 ) with 2 short mds, almost of equal length. Maxilla ( Fig. 48 ): stipes with 1 stps, 2 pfs of equal length, and 1 mbs, distinctly shorter than pfs, and 1 sensillum; with 4 straight dms, different in length; with 4 vms, short and almost of equal length. Maxillary palpi: length ratio of basal and distal palpomeres 1:1.25; basal palpomera with 1 short mpxs; distal palpomera with group of 3–4 conical, cuticular apical processes. Prementum ( Fig. 48 ) heart-shaped, with 1 prms; margin of ligula slightly rounded; ligula with 1 lig; premental sclerite distinct. Postmentum ( Fig. 48 ) with 3 pairs of pms, different in length.

THORAX AND ABDOMEN. Body length 4.3–6.6 mm (see Table. 1 ), elongate. Abdominal segments I–VI almost equal in length ( Fig. 53 ). Spiracles on abdomen in anteromedian parts of segments (abdominal seg. I–VIII).

Chaetotaxy of body rather reduced. Setae moderately long or short, and light yellow. Thorax. Prothorax ( Fig. 54 ) with 7 prn, 5 macro- and 2 microsetae; 2 moderately long ps of same length; 1 eus. Meso- and metathorax ( Fig. 54 ) with 1 prs; 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 long and 2 short pda. Abdomen. Abdominal segments I–VII ( Fig. 55 ) with 1 prs; 3 pds different in length; 2 ss of different length; 2 eps of different length; 2 ps; 1 lsts; and 2 short eus. Abdominal segment VIII ( Fig. 56 ) with 1 prs; 2 pds; 1 ss; 2 eps of different length; 2 ps; 1 lsts; and 2 short eus. Abdominal segment IX ( Fig. 56 ) with 2 ds of different length; 2 ps; and 1 sts. Each anal lobe on abdominal segment X ( Fig. 56 ) with 1 very short, feebly visible seta.

Description of pupa. COLORATION. Body salmon.

MORPHOLOGY ( Figs. 57–59 ). Body length 3.2–3.8 mm; widest part 1.3–1.9 mm (see Table. 1 ). Body rather stocky. Rostrum long, approximately 6 times as long as wide, reaching mesocoxae. Pronotum 1.7 times as wide as long.

CHAETOTAXY ( Figs. 57–59 ). Setae distinct, moderately long, unequal in length, light brown; on pronotum and head placed on small protuberances. Head capsule including 2 vs, 1 os, and 1 pas. Rostrum with 1 rs located medially. Vs 1 and os as long as setae on pronotum, distinctly longer than vs 2, pas and rs. Pronotum with 2 as, 2 ls, 2 ds, and 1 pls; ds distinctly smaller than other setae on pronotum. Dorsal part of meso- and metathorax with 1 seta. Each apex of femora with 1 fes. Setae on abdominal segments I–VIII placed medially and laterally; all abdominal setae located on small, conical protuberances. Pseudocerci slender, slightly curved inside.

Biological observations. Some adults were collected at the end of April when the plants were flowering and there were no mature pods. At the end of May the pods were mature in most plants and the adults were lacking. About 15 % of collected pods were infested by larvae of T. brisouti . Pupation was observed 10 days after the introduction of the larvae in the soil. Adults were observed in the cells 10 days later. After 30 days they had not left the cell and were manually removed.

Remarks. Tychius brisouti is a rare monophagous species on Astragalus monspessulanus and only known from a few localities of south-eastern Spain, southern France and north western Italy. However the observation about the collecting methods for T. alpinus can be applied also for this species.

Figures

FIGURES 47–52. Tychius brisouti mature larva head, antenna and mouth parts: 47—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); 48—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.); 49—right mandible (mds—mandible dorsal s.); 50—antenna; 51—labrum and clypeus (lms—labral s.); 52—epipharynx (ams—anteromedial s., als—anteriolateral s., mes—median s., lr—labral rods).

FIGURES 53–56. Tychius brisouti mature larva habitus: 53—lateral view, 54—lateral view of thoracic segments, 55—lateral view of abdominal segment I., 56—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.).

FIGURES 57–59. Tychius brisouti pupa habitus: 57—ventral view, 58—dorsal view, 59—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., fes—femoral s., pc—pseudocerci).