Graptus triguttatus triguttatus

Gosik, Rafal, Sprick, Peter & Morris, Michael G., 2019, Descriptions of immature stages of four species of the genera Graptus, Peritelus, Philopedon, and Tanymecus and larval instar determination in Tanymecus (Coleoptera, Curculionidae, Entiminae), ZooKeys 813, pp. 111-150 : 113-119

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Graptus triguttatus triguttatus


Graptus triguttatus triguttatus

Specimens examined.

5 premature larvae: Germany, Niedersachsen, Braunschweig, apple orchard and meadow in the area of Julius-Kühn-Institut (JKI), all under Plantago lanceolata L.; 10.01.2013: 3 ex., 18.04.2013: 1 ex., 24.05.2013: 1 ex.

22 mature and penultimate instar larvae: same site as previously noted, 10.1.2013: 5 ex., 18.04.2013: 7 ex., 03.05.2013: 7 ex., 24.05.2013: 1 ex., 10.06.2013: 2 ex.

3 pupae: Germany, Niedersachsen, Braunschweig, JKI, apple orchard, meadow; 2 mature larvae, collected on 24.05. and 10.06.2013, both had developed into the pupal stage in breeding boxes in the laboratory in Hannover on 20.06.2013. Another mature larva from the same site, collected on 03.05.2013, developed into the pupal stage before 27.05.2013.

Description of the mature larva.

Body length: 6.8-8.5 mm, body width: 3.0-3.4 mm, head width: 1.53-1.55 mm, head height: 1.35-1.37 mm.

Body (Figs 1-3). Moderately slender, curved, rounded in cross section. Prothorax slightly narrower than mesothorax; metathorax as wide as mesothorax. Abdominal segments 1-6 of almost equal length; 7-9 decreasing gradually to the terminal body part; 10 reduced to 4 anal lobes with the largest in dorsal and the smallest in ventral position, lateral lobes of equal size (Fig. 3). Spiracles (of thoracic and abdominal segments 1 -8) annular with 2 vestigial airtubes. Chaetotaxy well developed, setae capilliform, variable in length, dark yellow to brown. Each side of prothorax (Fig. 13) with 8 prns of unequal length: 5 of them placed on the weakly visible premental sclerite, next 3 short setae close to spiracle; 2 ps and 1 eus. Meso- and metathorax (Fig. 13) on each side with 1 short prs, 4 pds, variable in length: first, third and fourth long, second very short, 1 short as, 3 short ss, 1 moderately long eps, 1 moderately long ps and 1 eus. Each pedal area of thoracic segments with 6 pda, variable in length. Abd. 1-7 (Figs 14-17) on each side with 1 short prs, 5 pds variable in length(first, third and fifth long, second and fourth short) and arranged along the posterior margin of each segment, 1 minute and 1 short ss, 2 eps and 2 ps of various length, 1 lsts and 2 short eus. Abd. 8 (Figs 15-17) on each side with 1 short prs, 4 pds variable in length (first and third moderately long, second and fourth long) and arranged along the posterior margin of the segment, 1 minute ss, 2 eps and 2 ps of various length, 1 lsts and 2 short eus. Abd. 9 (Figs 15-17) on each side with 3 ds (dorsal setae), first moderately long, second and third long, all located close to the posterior margin of the segment, 1 long and 1 minute ps and 2 short sts. Each lateral anal lobe (Abd. 10) with a pair of minute setae.

Head (Fig. 18). Light to dark yellow, oval, frontal suture distinct, Y-shaped, endocarina present, reaching to middle of frons. Setae on head capilliform; des1, 2, 3, 5 equal in length; des1 and des2 located in the central part of epicranium, des3 placed on frontal suture, des5 located anterolaterally; fs4, 5 equal in length, fs4 located anteromedially, fs5 anterolaterally, close to epistome; les1 and les2 equal in length, less than half the length of des1; ves short, poorly developed. Postepicranial area with 3 very short pes (Fig. 18). Two weakly visible stemmata close to des5. Antennae (Fig. 19) located at the end of frontal suture; antennal segment membranous, bearing sensorium (Se) conical, almost as wide as long, located medially, and 6 sensilla of different types: 1 sa and 5 sb. Labrum (Fig. 20) almost semicircular, anterior margin rounded; 3 pairs of lrs, different in length, lrs1 and lrs2 very long, lrs3 moderately long; lrs1 placed medially, lrs2 anteromedially, lrs3 anterolaterally. Clypeus (Fig. 20) trapezoid, its anterior margin slightly concave, covered with asperities; 2 pairs of cls short, located posteromedially; clss clearly visible, placed medially between cls. Epipharynx (Fig. 20) with 3 pairs of finger-shaped als of almost equal length; 3 pairs of ams: ams1 and ams3 rod-shaped, very short, ams2 finger-like, very long; 2 pairs of rod-shaped mes of various lengths: first pair placed medially, second pair anteriorly, very close to ams. Surface of epipharynx smooth. Labral rods elongate, converging posteriorly. Mandibles (Fig. 21) curved, narrow, with slightly divided apex (teeth of various lengths). There is an elongate protuberance on the cutting edge between the apex and the middle of the mandible; both mds capilliform, different in length, placed transversely. Maxilla (Figs 22-24) with 1 stps and 2 pfs of equal length; mala with 7 finger- or rod-like dms of almost equal size, 4 vms, varied in length and all shorter than dms; mbs short. Maxillary palpi with 2 palpomeres, basal with short mps; distal palpomere apically with a group of sensilla, each palpomere with a pore. Basal palpomere distinctly wider than distal, both of almost equal length. Prelabium (Fig. 24) cup-like with 1 moderately long prms, located medially. Ligula with 3 pairs of minute ligs. Premental sclerite clearly visible, trident-shaped, posterior extension with acute apex. Labial palpi 2-segmented; apex of distal palpomere with some sensilla; each palpomere with a pore. Basal palpomere distinctly wider than distal, both of almost equal length. Postlabium (Fig. 24) with 3 capilliform pms (postlabial setae), the first pair located anteromedially, the remaining 2 pairs posterolaterally; pms1 and pms3 very short, pms2 twice as long as others.

Description of the pupa.

Body length (♂, ♀): 7.5-9.0 mm; body width (at level of mesocoxae): 3.8-4.5 mm; width of thorax: 2.0-2.3 mm.

Body moderately slender, straight, yellowish. Cuticle smooth (Figs 25-27). Rostrum short, 1.2 times as long as wide, extended beyond procoxae. Antennae moderately long and slender. Pronotum almost 1.8 times as wide as long. Abdominal segments 1-4 of almost equal length, segments 5-7 decreasing gradually, 8 semicircular, 9 distinctly smaller than previous segments. Urogomphi absent (Figs 25-27).

Chaetotaxy well developed, setae variable in lengthand shape: spine-like or capilliform, dark yellow to brown, usually located on visible protuberances. Head capsule and rostrum include 1 vs, 2 minute sos, 1 spine-like and 1 minute os, 2 pas, 3 rs of varied sizes and 1 minute es. Except sos and es, all setae of the head and rostrum are placed on protuberances. Pronotum with 2 as, 1 ls, 2 ds and 2 pls. All setae of pronotum spine-like, of equal size (only ds1 slightly larger than others); all setae placed on protuberances. Mesothorax with 2 minute setae placed anteromedially and 3 spine-like setae placed medially. Metathorax with 4 spine-like setae placed medially. Abdominal segments 1-7 with 7 pairs of d1-7: d1-6 short, spine-like, placed on protuberances, in lines along the posterior margin of segments, d7 short, capilliform, placed anterolaterally, and 2 minute l1-2. Setae no. 3 and no. 5 increasing gradually from segment 2 to 7. Segment 8 with 4 pairs of spine-like setae of varied lengths (d1-4), placed on protuberances, in lines along the posterior margin of the segment. Seta no. 2 distinctly larger than others. Segment 9 with 3 pairs of short, capilliform v1-3. Each apex of femora with 2 fes, spine-like and of various length.