Gymnetron Schoenherr, 1825

Skuhrovec, Jiri, Gosik, Rafal, Caldara, Roberto, Tosevski, Ivo & Batyra, Aleksandra, 2022, Description of immature stages of Gymnetron species (Coleoptera, Curculionidae, Curculioninae), with particular emphasis on the diagnostic morphological characters at the generic and specific levels, ZooKeys 1090, pp. 45-84 : 45

Genus Gymnetron Schoenherr, 1825

Description of mature larva (L3).

Measurements (in mm). Body length: 2.16-3.00. The widest point in the body (meso- and metathorax) measures up to 1.20. Head width: 0.36-0.53.

General. Body elongate or relatively elongate, slender, weakly curved, rounded in cross section.

Colouration. Pale yellow or dark brown head. All thoracic and abdominal segments white, cuticle smooth or with many reddish or brown asperities.

Vestiture. Setae on body thin, distinctly different in length (minute to very short or long).

Head capsule. Head almost oval or suboval, endocarinal line present. Frontal sutures on head distinct, extended to antennae. One stemma, in the form of a pigmented spot with convex cornea, both located on each side anterolaterally, above frontal suture. Dorsum of epicranium with three or five setae; des1 located in central part of epicranium; des2 lateral, sometimes absent; des3 located anteriorly on epicranium close to frontal suture; des4 often medially, sometimes absent; des5 located anterolaterally. Frons with three to four fs, fs1 absent, fs2 located medially, fs3 sometimes absent, fs4 and fs5 subequal. Head with two les, one or two ves, and two to six pes.

Antennae located at end of frontal suture on each side, membranous and distinctly convex basal article bearing one conical sensorium, relatively long.

Clypeus trapezium-shaped, ~ 3-4 × as wide as long with two relatively long cls, located posterolaterally.

Mouth parts. Labrum ~ 3-4 × as wide as long, with three piliform lms, relatively long; anterior margin doubly sinuate. Epipharynx with two or three long digitate als; with two or three ams, and one or without mes; labral rods indistinct. Mandibles distinctly broad, bifid, teeth of unequal height; slightly truncate; both mds relatively long, piliform, located in distinct holes. Maxilla: stipes with one stps, two pfs and sensillum, with or without mbs; mala with four or five elongated digitate dms; three or four vms, of various length; all vms distinctly shorter than dms. Maxillary palpi with two palpomeres; basal palpomere with one mxps and one sensillum; distal palpomere with one sensillum and a group of conical, cuticular apical processes. Praelabium oval, with one prms; ligula with two ligs. Labial palpi with one palpomere; palpomere with one sensillum and short, cuticular apical processes. Postlabium with two or three pms, all located laterally; membranous area finely or distinctly asperate.

Thorax. Prothorax distinctly smaller than meso- and metathorax. Spiracle unicameral, situated between pro- and mesothorax (see Material and methods). Prothorax with seven to eleven prns; two ps; and two eus. Mesothorax with or without two prs; two or three pds; one long as; two or three ss; one eps; one ps; and one or two eus. Each pedal area of thoracic segments well separated, with three or five pda.

Abdomen. Abdominal segments I-III of almost equal length, next abdominal segments shortening gradually to the terminal parts of the body. Abdominal segment X reduced to four anal lobes of unequal size, the lateral lobes being distinctly the largest, and the dorsal and ventral ones very small. Anus located terminally; ambulatory ampullae bilobate to circular. Spiracles unicameral, seven abdominal spiracles located laterally. Abdominal segments I-VI with one or two prs; one or two pds; two ss; one eps; one or two ps; one lsts and one or two eus. Abdominal segments VII-VIII without, one or two prs; one or two pds; one or two ss; one eps; one or two ps; without or one lsts; and one or two eus. Abdominal segment IX with one or two ds; one or two ps; and one or two sts. Abdominal segment X with one or two setae (ts).

Description of pupa.

Measurements (in mm). Body length: 1.87-2.73. Body width: 0.62-1.55. Thorax width: 0.67-1.12.

Body. Moderately stout, yellowish or brownish. Pronotal protuberances (p-pr) sclerotized, prominent, body covered with fine, knobby asperities; fused at base or well separated. Rostrum rather or moderately slender, ~ 4 × as long as wide, extending to mesocoxae. Antennae rather short, clava smooth. Pronotum 1.5-2.2 × as wide as long. Mesonotum slightly or sometimes distinctly smaller than metanotum. Abdominal segments I-V of equal length; segments VI-VIII tapering gradually to the terminal part of the body, segment IX distinctly reduced. Spiracles on abdominal segments I-V functional. Urogomphi reduced or short. Abdominal segment VIII with well visible conical abdominal protuberance dorsally (a-pr), extending the outline of the body.

Chaetotaxy. Sparse, setae of different lengths, transparent. Head with one or two os. Rostrum with or without one rs. Pronotum with one or two as, one or two ds, with two or without sls, one or three ls and three or four pls. Dorsal parts of meso- and metathorax with two or three setae. Apex of femora with one or two fes. Abdominal segments I-VIII with two or five setae dorsally. Each lateral part of abdominal segments I-VIII with one or two setae. Ventral parts of abdominal segments I-VIII with two or three setae. Abdominal segment IX with two setae ventrally.