Anthonomus (s. str.) latior Pic, 1902

Zabulev, Ilya A., 2021, Contribution to the knowledge of the immature stages of Palaearctic species of the genus Anthonomus Germar (Coleoptera: Curculionidae), Zootaxa 5032 (4), pp. 451-488 : 472-477

Anthonomus (s. str.) latior Pic, 1902

Figs. 67–83 , 103 .

Material examined. 12 larvae and 13 pupae, 16.06.2021, and 4 pupae, 28.06.2020, Russia, Primorsky Krai, Ussuriysky Urban Okrug, near Yakonovka vill. (43.736662°N 131.699975°E), ex flower buds of Crataegus pinnatifida Bunge , leg. and det. I.A. Zabaluev ( IZCS) .

Description of mature larva. Figs. 67–77 .

Measurements (in mm). Body length: 3.11–3.96 (mean 3.54). Body width: 1.71–2.09 (mean 1.95). Head width: 0.76–0.84 (mean 0.80).

Body from white to yellowish, distinctly C-shaped curved ( Fig. 67 ). Pronotum with a poorly visible yellowish shield. Spiracles ( Fig. 68 ) bicameral, air tubes with five annuli, one pair located on the prothorax and eight pairs located laterally on the abdominal segments I–VIII (Ab1–8). All setae of thoracic and abdominal segments hairlike, from very long to minute, yellowish. Prothorax (Th1) ( Fig. 69 ) with ten prns of unequal length (prns 1 —medium, prns 6 —short, others—from long to very long), two very long ps equal length and two eus (short and minute). There are two distinct sensilla—one located near the base of prns 1, the other—the base of prns 3. Meso- (Th2) and metathorax (Th3) ( Fig. 69 ) with three prs (one short and two minute), four pds different in length (pds 1 and pds 3 —long, pds 2 and pds 4 —short), one long as, three ss (long, short and minute), one very long eps, one long ps and two eus (short and minute). Pedal lobe with five pda different in length: pda 1 long, pda 4 medium, pda 2 short, pda 3 very short, pda 5 minute; pda 5 located close to the anterior edge of the segment; and with two small sensilla located between pda 2 and pda 3. Abdominal segments I–VIII (Ab1–8) ( Fig. 70 ) with two prs (short and minute), five pds different in length (pds 1, pds 3, and pds 5 —long; pds 2 and pds 4 —short), three ss (long, short and minute), two eps (long and short), one very short ps, one very short lsts and three minute eus. Abdominal segment IX (Ab9) ( Fig. 71 ) with six fine setae dorsally (ds), two short ps and one very short sts. Abdominal segment X (Ab10) without setae.

Head capsule ( Figs. 67 , 72 ) pale yellow, strongly sclerotized, especially along the anterior margin, suboval. Endocarinal line present, reaching behind middle of the frons and about 2/3 as long as frons. Frontal sutures distinct, extending to antennae. One stemma (st) present close to antenna. Dorsal setae (four des): des 1 and des 2 short, des 3 and des 5 long, des 4 absent; des 1 located near to middle part of epicranium, des 2 —in front of the posterior part of epicranium, des 3 close to frontal suture, des 5 —anterolaterally. There is one dorsal sensillum between des 3 and des 5. Frontal area with four fs: fs 1 and fs 3 minute; fs 2 absent; fs 4 and fs 5 long, and with two sensilla—one is between fs 1 and fs 3, the other—laterally from the base of fs 4. Lateral setae: les 1 short, les 2 very long. Ventral setae: two short vcs, approximately equal length. Posterior epicranial area with four minute pes and with two sensilla—one is between pes 3 and endocarinal line and the other near des 1. Antenna ( Figs. 73 , 103 ) is one-segmented, consisting of a basal membranous segment bearing a short-conical porous sensorium (se) and five sensilla: one ampullacea (sa), three styloconium (ss) and one basiconicum (sb).

Clypeus and mouthparts. Clypeus ( Fig. 74 ) trapezium - shaped, with slightly sinuated anterior margin and with two very short cls placed close to anterior margin of frons and clypeal sensillum (clss) located between them. Labrum ( Fig. 74 ) with three lrs: lrs 2 and lrs 3 long, subequal length, lrs 1 short, about 1/2 as long as lrs 2. Epipharynx ( Fig. 75 ) with two ams (ams 1 about 2/3 as long as ams 2), three finger-like als and two short mes. Labral rods (lr) moderately long, converging slightly posteriorly. One sensillum located on both sides of lr and four combined in a single median cluster (esc). Mandibles ( Fig. 76 ) stout, triangular, with two apical teeth; with two robust mds (mds 2 is slightly longer than mds 1), and one mandibular sensillum. Maxilla ( Fig. 77 ) with one very long stps, two long pfs, very short mbs and three sensilla. Mala on the dorsal side with a row of five finger-like dms, on the ventral side with five acuminate vms (three comparatively long and two comparatively short). Maxillary palpi consists of two palpomere: basal palpomere transverse, with one short mxps and two sensilla, distal—conical, with one simple sensillum, one digitiform sensillum (sd) laterally, and eleven basiconicum sensilla (sb) at the apex. Prelabium cup-like with four sensilla and one medium prms; ligula with three ligs. Labial palpi elongated, one-segmented, with one sensillum medially and nine basiconicum sensilla (sb) at the apex. Postlabium with three pms: pms 1 medium, about 1/3 as long as pms 2, pms 2 —very long, pms 3 —medium, as long as pms 1.

Description of pupa. Figs. 78–80 .

Measurements (in mm). Body length: 3.37–3.76 (mean 3.57). Body width: 1.67–1.70 (mean 1.69). Head width: 0.62–0.67 (mean 0.65).

Coloration. For whitish yellow to yellowish white. In specimens ready to hatch, head, rostrum, apex of femora, and urogomphi are brownish, and apical part of the wings and elytra are also slightly darkened.

Body is rather short and gross. Rostrum relatively short, 3.0–3.2x as long as wide; male and female rostrum of the same length. Pronotum transverse, 1.3x as wide as long. Prothoracic depressions lacking. Spiracles well developed on Ab1–5, and vestigial on Ab6.

Chaetotaxy. Setae yellowish, slightly curved, from long to minute. Head capsule with one vs and one os; vs almost straight, 1/2 as long as the width of the rostrum at the base, os slightly longer than vs. Rostrum with one rs placed posterior to its middle, about 1/2 as long as the rostrum width at the same place, and with one very short (about 1/3 as long as rs) and fine pas, placed at the base of the rostrum. Pronotum (Th1) with one as, two ds, two sls, and three pls; as 1 thin, medium length (noticeably longer than the tubercle height), located subapically on anterior surface of the tubercle of medium size; ds 1 minute, located subapically on anterior surface of the very large tubercle, which larger than those elsewhere on pronotum; ds 2 medium length, located subapically on anterior surface of the large prominent spiniform tubercle; sls 1–2 and pls 2–3 long, approximately equal length, pls 1 a little shorter than the others, all setae located near bases of small pointed tubercles. Femora without fes. Meso- (Th2) and metanotum (Th3) with three long dorsal setae (d) placed medially, they located on the posterior surface of large sharply pointed tubercles; the size of the tubercles and the length of the setae gradually decrease towards the middle line. Abdominal tergites (Ab1–8) with three distinct dorsal setae (d), d 1 noticeably thinner and shorter than others, d 2 and d 3 approximately equal length, d 1 on Ab8 located at the bases of low rounded tubercules, d 2 on Ab6–8 located at the base of small convex tubercles, d 3 on Ab6–8 located at the bases of sharply pointed tubercles. There are minute and inconspicuous setae between d 1 and d 2 and between d 2 and d 3. Lt 1 minute, located at the bases of a small sharply pointed tubercles (rounded on Ab1–2); lt 2 long, on Ab3–8 located near the bases of large spiniform tubercles, on Ab1–2—small rounded tubercles. The size of all tubercles gradually increases towards the apex of the abdomen. L s absent. Ab9 with one very fine and short ventral setae (v). Urogomphi as A. conspersus , without setae.

Biological observations. Several adults were collected on 28.06.2020 by shaking Crataegus pinnatifida (host plant recorded for the first time) at the edge of oak ( Quercus mongolica Fisch. ex Ledeb. ) forest ( Fig. 81 ). At the same time dried flower buds containing pupae and young adults were collected. Later (2.07.2020), large numbers of beetles of a new generation were collected on the same plants. When observed in Petri dishes, beetles most active fed on green Crataegus fruits, gnawing small holes in them, and somewhat less actively on leaves, skeletonizing them ( Fig. 82 ). In addition to C. pinnatifida , the weevils were offered the fruits and leaves of C. sanguinea Pall. , which were also actively eaten ( Fig. 83 ). Feeding was observed for about 14 days (some beetles were active for up to 28 days), after which most of the weevils have formed an accumulation in the fold of a dry leaf and entered a state of inactivity. In 2021, additional material including larvae was collected from the same plant. Several larvae were parasitized by unidentified Pteromalidae (Hymenoptera) .

Figures

FIGURES 67–71. Anthonomus latior, mature larva. 67—habitus of the body and frontal view of head, 68—thoracic spiracle, 69—lateral view of thoracic segments, 70—lateral view of abdominal segment I, 71—lateral view of abdominal segments VIII–X (setae: as—alar, ds—dorsal, eps—epipleural, eus—eusternal, lsts—laterosternal, pda—pedal, pds—postdorsal, prns— pronotal, prs—prodorsal, ps—pleural, ss—spiracular, sts—sternal).

FIGURES 72–77. Anthonomus latior, mature larva head and mouthparts. 72—head, frontal view, 73—antenna, 74—clypeus and labrum, 75—epipharynx, 76—left mandible, 77—maxillolabial complex, ventral aspect (apical part of the right maxilla is shown in dorsal aspect) (at—antenna, clss—clypeal sensilla, lr—labral rods, st—stemma; setae: als—anterolateral, ams—anteromedial, cls—clypeal, des—dorsal epicranial, dms—dorsal malar, fs—frontal, ligs—ligular, lrs—labral, ls—lateral epicranial, mbs—basiventral malar, mds—mandibular, mes—median, mxps—maxillary palp, pes—postepicranial, pfs—palpiferal, pms—postlabial, prms—prelabial, stps—stipal, vms—ventral malar).

FIGURES 78–80. Anthonomus latior, pupa habitus and chaetotaxy. 78—ventral view, 79—dorsal view, 80—lateral view (Th1– 3—number of thoracic segments, Ab1–9—number of abdominal segments, sp—spiracle; setae: as—apical, d—dorsal, ds—discal, lt—laterotergal, os—orbital, pas—postantennal, pls—posterolateral, rs—rostral, sls—superlateral, v—ventral, vs—vertical).

FIGURES 81–83. Anthonomus latior, biotope and host plant. 81—biotope (Primorsky Krai, Yakonovka), 82—adults feed on the leaves Crataegus pinnatifida, 83—the same on the leaves C. sanguinea.

FIGURES 98–106. Antennae and maxillary palpi of Anthonomus (SEM images). 98—A. pinivorax, 99—antenna of A. rubripes, 100—maxillary palp of A. rubripes, 101—A. incurvus, 102—A. conspersus, 103—A. latior, 104—A. pedicularius, 105—A. pomorum, 106—A. rubi (se—sensorium, sa—sensilla ampullacea, sd—sensilla digitiform, ss—sensilla styloconium, sb—sensilla basiconicum). Scale bars 10 μm.