Tychius (s. str.) meliloti Stephens, 1831

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 : 22-23

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https://doi.org/ 10.11646/zootaxa.3839.1.1

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Tychius (s. str.) meliloti Stephens, 1831


Tychius (s. str.) meliloti Stephens, 1831 View in CoL

Clark et al. 1878: 646. Caldara 1990: 179.

Material examined. 18 larvae from pods of Melilotus alba collected 30.vii.1982 at Rozzano , Milano province, Lombardia ( Italy), leg. R. Caldara, and 22 pupae reared from larvae collected contemporaneously together with the others, all determined by association with reared adults.

Differential diagnosis. See Tables 2 View TABLE 2 and 3 View 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: 0.38–0.42 mm (see Table. 1 View TABLE 1 ). Endocarinal line absent. Des 1 located almost in central parts of epicarnium; des 2 located very near frontal suture, near des 3; des 4 located anterolaterally; des 5 located laterally; des 2 and des 4 4 times shorter than others (des 1, des 3, des 5) ( Fig. 177 View FIGURES 177–182 ). Fs 1 and fs 2 absent; fs 3 short, located medially; fs 4 located anteromedially (along epistoma); fs 5 located anterolaterally (along epistoma), 3 to 4 times longer than fs 3 ( Fig. 177 View FIGURES 177–182 ). Les almost as long as des 3. Ves very short. Post epicranial area with group of 3 minute pes. Antennal segment membranous, bearing conical sensorium and 2 very short, conical, sensilla. ( Fig. 180 View FIGURES 177–182 )

Labrum ( Fig. 181 View FIGURES 177–182 ) approximately 3.2 times as wide as long; lms 1 distinctly longer than lms 3, lms 2 of same length as lms 1; anterior margin slightly curved inside. Clypeus ( Fig. 181 View FIGURES 177–182 ) 3.25 times as wide as long; with 1 short cls located posterolaterally; anterior margin rounded. Epipharynx ( Fig. 182 View FIGURES 177–182 ) with 2 pairs of als, almost of equal length; with 2 pairs of short ams, ams 1 distinctly longer than ams 2; with 2 long finger-like and 1 short mes; labral rods short, kidney-shaped, converging posteriorly. Mandibles ( Fig. 179 View FIGURES 177–182 ) with 2 short mds, almost of equal length. Maxilla ( Fig. 178 View FIGURES 177–182 ): stipes with 1 stps, and 2 pfs of equal length; mala with 4 curved dms, different in length; with 3 vms, short and almost of equal length. Maxillary palpi: length ratio of basal and distal palpomeres almost 1:1; basal palpomera with 1 short mpxs; distal palpomera with group of 3–4 conical, cuticular apical processes. Prementum ( Fig. 178 View FIGURES 177–182 ) trapezoid, with 1 prms; margin of ligula slightly sinuate, ligula with 1 lig; premental sclerite distinct. Postmentum ( Fig. 178 View FIGURES 177–182 ) with 3 pairs of pms, different in length.

THORAX AND ABDOMEN. Body length 2.1–2.6 mm (see Table. 1 View TABLE 1 ), elongate. Abdominal segments I–VI almost of equal in length ( Fig. 183 View FIGURES 183–186 ). Spiracles on abdomen in anteromedian parts of segments (abdominal seg. I–VIII).

Chaetotaxy of body reduced. Setae moderately short or short, and light yellow. Thorax. Prothorax ( Fig. 184 View FIGURES 183–186 ) with 8 prn; 4 macro- and 4 microsetae; 2 moderately long ps of same length; 1 eus. Meso- and metathorax ( Fig. 184 View FIGURES 183–186 ) with 1 prs; 2 pds, different in length; alar area with 1 short as; 1 short ss; 1 eps; 1 ps; and 1 short eus. Each pedal area of thoracic segments well-separated and with 3 pda, equal in length (moderately long). Abdomen. Abdominal segments I–VII ( Fig. 185 View FIGURES 183–186 ) 2 pds of different length; 2 ss; 1 eps; 1 ps; and 2 short eus. Abdominal segment VIII ( Fig. 186 View FIGURES 183–186 ) 1 pds; 2 ss; 1 eps; 1 ps; and 2 short eus. Abdominal segment IX ( Fig. 186 View FIGURES 183–186 ) with 1 ds; 1 ps; and 1 sts. Anal lobes on abdominal segment X ( Fig. 186 View FIGURES 183–186 ) with 1 very short, feebly visible seta.

Description of pupa. COLORATION. Body salmon.

MORPHOLOGY ( Figs. 187–189 View FIGURES 187–189 ). Body length 1.6–2.2 mm; widest part 0.8–1.1 mm (see Table. 1 View TABLE 1 ). Body rather stocky. Rostrum very long, approximately 7 times as long as wide, almost reaching metacoxae. Pronotum 1.6 times as wide as long.

CHAETOTAXY ( Figs. 187–189 View FIGURES 187–189 ). Setae distinct, moderately long, unequal in length, light brown; on pronotum and head placed on small protuberances. Head capsule including 1 vs, 2 os of different length, and 1 pas. Rostrum without setae. Vs and os 1 as long as setae on pronotum, distinctly longer than os 2 and pas. Pronotum with 2 as, 2 ls, 1 ds, and 1 pls; ds distinctly smaller than 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 medially and laterally; all abdominal setae located on small, conical protuberances. Pseudocerci conical, short.

Biological observations. Pupation was observed 8 days after the entrance of larvae into the soil. Duration of the pupal stage was 6 days. Adults quickly emerged at the surface 2–3 days later. At the moment of the collection of the mature pods adults were very common and several of them were in copula

Remarks. In the same plants where T. meliloti was collected, there were also many adults of T. breviusculus (see the remarks of this species for further details). Previously there was only incomplete information on immatures of this species. In fact Clark et al. (1978) mentioned that Scherf (1964) provided a brief description of larva without illustration and that this description corresponds with their generic description.


Departamento de Geologia, Universidad de Chile













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