Rhinusa Stephens, 1829

Gosik, Rafal, Caldara, Roberto, Tosevski, Ivo & Skuhrovec, Jiri, 2024, Description of immature stages of Rhinusa species (Coleoptera, Curculionidae, Mecinini) with a focus on diagnostic morphological characters at the species and genus levels, ZooKeys 1195, pp. 1-94 : 1

Rhinusa Stephens, 1829

Description of mature larva (L3).

Measurements (in mm). Body length: 2.00 ( R. florum ) - 9.00 ( R. asellus ). The widest point of the body (metathorax) measures up to 2.35 ( R. vestita ). Head width: 0.46 ( R. florum ) - 1.05 ( R. vestita ).

General. Body elongate, slender, curved, and usually rounded in cross section. All thoracic segments almost equal in size, or pronotum smaller than the next segments. Meso- and metathorax each divided dorsally into two folds, the prodorsum distinctly smaller than postdorsum or even vestigial. The pedal fold of thoracic segments very distinct, usually conical, and prominent. Abdominal segments I-VI of similar size, next segments tapering towards the posterior body end. Abdominal segments I-VII each divided dorsally into two transverse folds: prodorsum slightly smaller than postdorsum; postdorsum usually higher than prodorsum or in the form of conical protuberances; seldom both folds equally raised. Segments VIII and IX dorsally undivided. Epipleural fold of segments I-VIII conical. Laterosternal and eusternal folds of segments I-VIII conical, usually weakly distinct. Thoracic and abdominal cuticle densely covered with fine, unicoloured cuticular asperities. Abdominal segment X divided into four folds of equal size; almost completely hidden by the previous segment. Anus situated ventrally.

Thoracic spiracles often unicameral, but sometimes bicameral ( R. antirrhini , R. florum , and R. melas ), abdominal spiracles always unicameral; thoracic spiracles placed laterally on prothorax, close to mesothorax; abdominal spiracles placed antero-laterally or antero-medially on segments I-VIII.

Colouration. Head capsule light yellow to dark brown, medial parts of epicranium usually less sclerotised. All thoracic and abdominal segments whitish or light yellow. Pronotal sclerite indistinct, not more pigmented than the rest of the segment (only in R. eversmanni and R. neta slightly more pigmented than the rest of the segment).

Vestiture. Setae on body thin, yellowish, different in length (very short or medium), transparent or brownish.

Head capsule. Head suboval or slightly narrowed bilaterally, endocarinal line present, reaching from 1/2 to 4/5 of the length of frons. Frontal sutures usually very wide, hardly or weakly distinct. Frons covered with knobby asperities ( R. collina , R. eversmanni , R. incana , and R. neta ) or smooth. Usually only one single pair of anterior stemmata present, in the form of small black spots (st) close to the end of the frontal suture, two pairs of stemmata present in R. asellus , R. collina , R. incana , and R. linariae . Des1 usually short or absent; des2 usually elongated, located on the lateral part of the epicranium; long des3 located anteriorly on the epicranium on the border of the frontal suture; des4 minute or absent; and des5 long, located anterolaterally. Fs1-3 minute or absent, located medially; fs4 long, located anteriorly; and long fs5 located anterolaterally, close to the antenna. Les1 and les2 medium to short; single ves short or absent. One to five minute postepicranial setae (pes).

Antennae placed distally of the frontal suture, on the inside. Membranous and distinctly convex basal article bearing one conical sensorium plus some smaller sensilla: ampullacea, basiconica, or styloconica.

Clypeus trapezoidal, usually with two cls short to relatively elongated; sometimes basal part much more sclerotised than the apical parts; anterior border more or less curved towards the inside.

Mouth parts. Labrum usually distinct from clypeus by clypeo-labral suture (in R. pilosa , R. rara , and R. linariae clypeus and labrum fused) with three piliform lrs (only in R. linariae single lrs), usually lrs1 and lrs2 elongated, located medially, and lrs3 short, located laterally; anterior border of labrum bi-sinuate or slightly rounded. Epipharynx mostly with two (rarely three) relatively elongated, finger-like als (almost identical in length); two or three piliform ams varying in size; without or with up to two short, finger-like mes; labral rods (lr) usually prominent, elongated, kidney-shaped, or rounded, almost indistinct. Mandibles apically bifid, cutting edge with additional protuberance or smooth; two medium-sized piliform mds, both located close to the lateral border. Maxillolabial complex: maxilla usually more sclerotised than labium, stipes with one stps, two pfs, and one mbs; stps and both pfs1-2 short to elongated; mala with four to six finger-like dms variable in length; from two up to four piliform vms, medium to short in length. Maxillary palpi two-segmented; basal palpomere usually distinctly wider than distal one; length ratio of the basal and distal palpomeres usually almost 1:1; basal palpomere with short mpxs and two sensilla, distal palpomere with a group of two to six apical sensilla in the terminal receptive area. Prementum close to oval-shaped, with one medium prms (only R. herbarum with two prms); ligula with round or sinuate margin and one to three ligs; premental sclerite sclerotised in cup or ring form, sometimes incomplete, only in R. linariae indistinguishable, posterior extension absent or elongated; anterior median extension absent. Labial palpi one-segmented (in R. linariae labial palpi vestigial and almost invisible); each palp with a single pore, and a group of one to four apical sensilla (ampullacea) in the terminal receptive area; the surface of the labium smooth. Postmentum with two or three pms; membranous area smooth or partially covered with sharp or knobby asperities.

Thorax. Prothorax with four to 12 prns; two ps; and usually a short, single eus. Mesothorax with a single minute prs or without; three to four pds (variable in length) (only in R. linariae one pds and in R. pilosa two pds); one medium as (only R. rara without); three medium to minute ss; one medium eps; one or two medium ps; and a single minute eus (sometimes absent). Chaetotaxy of metathorax almost identical to that of mesothorax. Each pedal area of thoracic segments with three to six pda.

Abdomen. Segments I-VIII usually with one minute prs (sometimes absent on segment VIII, only R. bipustulata with two prs) and one to four pds; usually one minute and one medium ss; one to three eps; one ps; one minute lsts; and usually two minute eus. Abdominal segment IX without or with up to three minute ds; without or with up to two minute ps; and without or with up to two minute sts. Abdominal segment X mostly without seta.

Description of pupa.

Measurements (in mm). Body length: 1.86 ( R. florum ) - 6.50 ( R. vestita ). Body width: 1.66-3.50. Thorax width: 1.00-2.00.

Body. Integument white, sometimes with some parts dark and sclerotised; setae sometimes placed on pigmented spots, more or less stout, curved. Head with a pair of protuberances (h-pr) above eyes. Rostrum moderately elongated, in males usually as long as in females or only slightly shorter than in females, reaching mesocoxae (only in R. asellus rostrum very elongated, distinctly variable in both sexes, much longer in females). Pronotum trapezoidal. Pronotal protuberances (p-pr) separated at bases, wider than tall (conical in R. asellus ), sometimes vestigial ( R. linariae ) or even absent ( R. herbarum , R. pilosa , and R. rara ). Meso- and metanotum similar in size. Abdominal segments I-VI almost identical in size; segment VII semicircular; segment VIII narrow, small; segment IX reduced. Abdominal protuberance (a-pr) on abdominal segment VIII usually visible, flattened or rounded, sometimes vestigial ( R. linariae ) or even absent ( R. collina , R. eversmanni , R. pilosa , and R. rara ). Urogomphi (ur) short, often ending in sclerotised, sharp apexes, sometimes vestigial or completely absent.

Chaetotaxy well developed, setae short to elongated, transparent or brownish. Head without or with one os, without or with one sos; rostrum without or with one pas, without or with up to two rs, without or with one es. Pronotum with one to three as, without or with up to four ls, two to four pls; without or with one ds. Dorsal parts of meso- and metathorax with two or three setae placed medially. Apex of femora usually with a single long fes, with two fes in R. asellus , R. tetra and R. bipustulata . Abdominal segments I-VII with two or up to six setae dorsally (segment VIII usually with fewer setae); one or two setae laterally, and two or up to five setae ventrally. Abdominal segment IX with two or up to four setae ventrally.

Descriptions of the species

Species are arranged according to the species groups proposed by Caldara et al. (2010) on the basis of a morphological study of the adults. For each group, a combination of the diagnostic characters is here listed, whereas a key to all the groups is reported by Caldara and Toševski (2019).

Rhinusa tetra group

Adult diagnosis. Protibiae and metatibiae with a premucro, which is more pronounced in female; uncus of protibiae with base placed towards middle of apex and almost as long as width of tibiae in female, protibiae in male distinctly arcuate in apical quarter, profemora very globose, ventrites 3-5 in male along midline with hairlike scales dense and ruffled.