Larinus

Gosik, Rafał & Skuhrovec, Jiří, 2011, Descriptions of mature larvae and pupae of the genus Larinus (Coleoptera: Curculionidae, Lixinae), Zootaxa 3019, pp. 1-25 : 10-14

Larinus (s. str.) pollinis (Laicharting, 1781) (= syn. brevis (Herbst, 1795))

Scherf 1964: 132 (key), 133 (description), Figs. 139-143; Nikulina et al. 2004: 25 (key).

Material. (54 larvae of different larval instars, 10 pupae), collected only in the flower heads (inflorescence) of carline thistle ( Carlina vulgaris L.): POLAND or., xerothermic grass communities in Stawska Góra near Chełm, UTM nets: FB 67, 13. and 20.viii. 2009 (48 spec. of different larval instars, 8 spec. of pupae); sand grass communities in Pieszowola near Urszulin, UTM nets: FC50, 10.ix.2009 (6 spec. of mature larvae); POLAND mer. or., xerothermic grass communities in Narol, UTM nets: FA68, 15.viii.2009 (2 pupae), all R. Gosik leg.

Differential diagnosis. Mature larva. Endocarina absent (x L. obtusus , L. sturnus , L. turbinatus ) ( Figs. 15, 16 ). Des 4 close to des 3 (x L. turbinatus ) ( Figs. 15, 16 ). More than 40 setae on pronotum (x L. obtusus , L. sturnus , L. turbinatus ) ( Fig 23 ). Spiracular area in meso- and metathoax with more than 8 ss (x L. obtusus , L. sturnus , L. turbinatus ) ( Fig 23 ). Abdominal segment I-VII with more than 5 prs, 25 pds, and 3 dpls (x L. obtusus , L. sturnus , L. turbinatus ) ( Fig 24 ). Setae on thorax and abdomen long ( Figs. 23, 24 ) (x L. turbinatus ). Pupa. Sas on head, no protuberance with a shape such as horns (x L. sturnus ) ( Figs. 26, 27 ). More than 40 setae on pronotum (x L. obtusus , L. sturnus , L. turbinatus ) ( Fig. 27 ). Many setae on both margins of abdominal segment I. (x L. obtusus , L. sturnus , L. turbinatus ) ( Fig. 27 ). Pc very short (x L. sturnus , L. turbinatus ) ( Figs. 26, 28 ).

Description of mature larva. COLORATION. Head brown or dark brown. All thoracic and abdominal segments dark-yellow or light-brown. Cuticle covered densely by thorn-like cuticular processes.

HEAD CAPSULE AND MOUTH PARTS. Head width: 1.8–2.0 mm (mean 1.9 mm), oval, endocarinal line absent ( Figs. 15, 16 ). Dorsal epicranial setae des 1, des 2 and des 4 located in central part of epicranium, des 3 located almost on frontal suture, des 5 anterolaterad, in the same length ( Figs. 15, 16 ). Frontal setae fs 1, fs 2 and fs 4 located along frontal suture, fs 3 in central parts of frons, fs 5 located on epistoma, all frontal setae of same length ( Figs. 15, 16 ). Lateral epicranial seta les and ventral epicranial seta ves slightly shorter than des 1-5. Epicranial area with group of 4 pores; one pore near to des 3, remaining three pores located laterally. Antenna with sensorium conical triangular, short, located medially; basal membranous article with 2 triangular sensillae ( Fig. 17 ).

Labrum ( Fig. 18 —left side) about 2 times as wide as long, with 3 pairs of hairform labial setae (lrms 1-3) in the different length; media pair of setae (lrms 2) twice shorter than lrms 1 and lrms 3; anterior margin sinuate. Clypeus ( Fig. 18 —left side) 3 times as wide as long with 2 pairs of short setae (cls 1, 2) of same length, located posterolaterad; anterior margin slightly rounded to inside. Epipharynx ( Fig. 18 —right side) with 5 pairs of blunt, finger-like anterolateral setae (als 1-5) in the different length; 2 pairs of anteromedial setae (ams 1, 2), almost same in shape and length; 2 pairs of short, blunt median setae (mes 1, 2); labral rods (lr) well visible, long, strong converging posterior. Mandibles ( Fig. 19 ) strong truncate; mandibla dorsal setae (mds 1, 2) unequal in length, short, hairform. Maxilla ( Fig. 20 ) stipes with 1 stipal (stps) and 2 palpiferal setae (pfs 1, 2), in the same length; mala with 10 slightly curved dorsal setae (dms 1-10) in the different length; ventral mala setae (vms 1-4) short, almost of same length; vms 1-4 distinctly shorter than dms 1-10; mala and stipes (partially) covered by conical cuticular processes. Maxillary palpi with two palpomeres; length ratio of basal and distal palpomeres: 1:0.6; basal palpomere with 1 maxillary palpi seta (mxps); distal palpomere with group of 6 conical, apical cuticular processes. Praelabium ( Fig. 21 ) heart-shaped, with 1 pair of prealabial setae (plbs); ligula with slightly sinuate margin and 2 pairs of hairform micro-setae (ligs 1, 2); premental sclerite well visible. Labial palpi with two palpomeres; length ratio of basal and distal palpomeres 1:0.5; distal palpomere with group of 4 conical cuticular apical processes; basal palpomere with 1 dorsal pore. Postlabium (pslb) ( Fig. 21 ) with 3 pairs of macro setae (pslbs 1-3), different in length, first pair located anteriorly, remaining two pairs laterally; lateral part of postlabium covered with conical, cuticular processes.

THORAX AND ABDOMEN. Body length: 8.50–13.00 mm (mean 10.50 mm) stocky, strongly curved ( Fig. 22 ). The widest place in the body (metathorax) to 3.40 mm. Abdominal segments I–III almost equal length, slightly smaller than abdominal segments IV–VI; next abdominal segments gradually decreasing to the terminal parts of the body. Spiracles on abdomen close to anterior margin of abdominal segments I–VIII ( Fig. 24 ).

Dorsal parts of thoracic and abdominal segments densely covered by long, hairform, light brown, well visible setae. Thorax. Prothorax ( Fig. 23 ) densely covered with more than 50 prodorsal setae (prns) in different length (difficult release exact count of setae), 5 ventropleural setae (vpls) and 5 mediosternal setae (msts). Mesothorax ( Fig. 23 ) with 10 prodorsal setae (prs), more than 50 postdorsal setae (pds) in different length, 1 seta on alar area, 11 setae (ss) in spiracular area, 2 dorsopleural setae (dpls), 5 ventropleural setae (vpls) and 5 mediosternal setae (msts). Chaetotaxy of metathorax ( Fig. 23 ) similar to mesothoracal, apart from dorsopleural area, where sometimes is only 1 dpls. Pedal area of thoracic segments well divided with 12 pda. Abdomen. Abdominal segments I–VII ( Fig. 24 ) with 9 prodorsal setae (prs), about 40 postdorsal setae (pds) in the different length, 9 setae (ss) in spiracular area, 6 dorsopleural setae (dpls), 3 ventropleural setae (vpls), 2 laterosternal setae (lsts) and 3 short mediosternal setae (msts). Abdominal segment VIII ( Fig. 25 ) with 3 prodorsal setae (prs), 8 postdorsal setae (pds) in the different length, 5 dorsopleural setae (dpls), 3 ventropleural setae (vpls), 2 laterosternal setae (lsts) and 1 short mediosternal seta (msts). Abdominal segment IX ( Fig. 25 ) with 6 dorsal setae (ds), 1 lateral seta (ls) and 1 sternal seta (sts). Each anal lobes of abdominal segment X ( Fig. 25 ) with 3 micro-setae.

Description of pupa. COLORATION. All thoracic segments ever more pigmented than color of abdominal segments. Cuticle spiculate, near dark brown bases of setae.

MORPHOLOGY ( Figs. 26–28 ). Body length: 7.5–7.7 mm, the widest place: 5.2–5.4 mm. Body stocky, curved, yellowish or brown. Rostrum rather long, about 2 times as long as wide, extended to mesocoxae. Antennae relatively long and slender. Pronotum 2.3 times as wide as long. Abdominal segments I, II larger than abdominal segments III–VI; next abdominal segments diminish gradually to the end of body. Abdominal segment VII almost semicircle; abdominal segments VIII and IX distinctly smaller than other ones.

CHAETOTAXY ( Figs. 26–28 ). Setae distinct, very long, hairform (apart from setae on head capsule and rostrum) in different length. Head capsule includes 1 vertical seta (vs); 2 super-orbital setae (sos 1, 2); 1 orbital seta (os) and 4 postantennal setae (pas 1-4). Rostrum with 1 rostral seta (rs), located apically. Setae on head capsule and rostrum straight, distinctly shorter than setae on thoracic and abdominal segments. Dorsal parts of all thoracic segments densely covered by setae. Exact count of setae difficult to release, therefore recognizing of setae in cause of this species seem to be impossible. Each apex of femora with 6 hairform setae (fes 1-6). All setae on thoracic segments of same length, hairform. Bases of setae with dark brown ring. Posterior margin of tergites on abdominal segments I– VIII densely covered with hairform setae. Individual setae distributed irregular also on remaining parts of dorsal parts of abdominal segments. There are also some thorn-like, dark brown cuticular processes, which formed a line along its anterior margin of abdominal segments I–VIII. Cuticular processes lift gradually on consecutive abdominal segments; at the end takes a form of long, divided claws on abdominal segment VIII. Lateral parts of abdominal segments I–VIII with groups of 7 setae located on protuberances. Abdominal segments I–VIII with 3 short ventral setae; distributed in regular lines. Abdominal segment IX with 3 pairs of micro ventral setae and 2 pairs short, thin dorsal setae. Pseudocerci short, conical.

Remarks. Measurements presented by Scherf (1964) did not agree with our results; body length of larvae 7–9 mm (our 5.8–6.2 mm) and body length of pupae 8–9 mm (our 7.5–7.7 mm). The difference could be caused by different quality of measurement, method of measurement and/ or as the thorax and abdomen are not sclerotized and may be affected also by the fixation process, body length and width are given only for comparison ( Table. 1 ). Scherf (1964) did not give any other measurements (e.g. head and/ or body width). Chaetotaxy is almost the same apart from a few details, e.g. count of les. Scherf (1964) recorded the presence of four les, but unlike he, we recorded only one seta in this region. Description of larvae and also of pupae by Scherf (1964) is relatively detailed and high quality. Unfortunately, we can not say the same about drawings, which are highly schematic and almost without any detailed information. Nikulina et al. (2004) mentioned this species only in their key, which is reproduced from Scherf (1964).

Figures

FIGURES 15 – 21. Larinus pollinis mature larva head, antenna and mouth parts: 15 — dorsal view, 16 — lateral view (des — dorsal epicranial s., fs — frontal s., les — lateral epicranial s., ves — ventral epicranial s., at — antenna, st — stemma), 17 — antenna, 18 (left side) — labrum and clypeus (cls — clypeal s., lrms — labral s.), 17 (right side) epipharynx (ams — anteromedial s., als — anterolateral s., mes — median s., lr — labral rods), 19 — right mandible (mds — mandible dorsal s.), 20 — right maxilla, dorsal view (dms — dorsally malae s., vms — ventrally malae s., mpxs — maxillary palps s., pfs — palpiferal s., stps — stipal s.), 21 — praelabium and postlabium, ventral aspect (plbs — prelabial s., pslbs — postlabial s., ligs — ligular s.).

FIGURES 22 – 25. Larinus pollinis mature larva habitus: 22 — lateral view, 23 — lateral view of thoracic segments, 24 — lateral view of first abdominal segment, 25 — lateral view of abdominal segments VIII – X (prns — pronotal s., dpls — dorsopleural s., vpls — ventropleural s., prs — prodorsal s., pds — postdorsal s., pda — pedal s., as — alar s., ss — spiracular s., lsts — laterosternal s., msts — mesosternal s., sts — sternal s., ls — lateral s., ds — dorsal s.).

FIGURES 26 – 28. Larinus pollinis pupa habitus: 26 — ventral view, 27 — dorsal view, 28 — lateral view (pc — pseudocerci, vs — vertical s., sos — super orbital s., os — orbital s., pas — postantennal s., rs — rostral s., fes — femoral s.).