Anthonomus (s. str.) rubi (Herbst, 1795)

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 : 479-484

Anthonomus (s. str.) rubi (Herbst, 1795)

Figs. 84–98, 106 .

Material examined. 2 larvae and 1 pupa, 20.07.1937, Ukraine, Poltava, ex buds of Rubus caesius L., leg. and det. D.A. Ogloblin ( ZISP) ; 1 larva, 7.07.1940, Russia, Leningrad region, Gatchina, ex buds of R. idaeus L., leg. and det. D.A. Ogloblin ( ZISP) .

Additional material. 12 larvae and 6 pupae, 9.06.1936, Kazakhstan, Alma-Ata, Glubokaya Shchel’, ex buds of Rosa sp. , leg. E.N. Samoilovich ( ZISP) .

Redescription of mature larva. Figs. 84–94 .

Measurements (in mm). Body length: 2.82–3.42 (mean 3.07). Body width: 1.55–1.89 (mean 1.69). Head width: 0.65–0.67 (mean 0.66).

Body from whitish to yellowish, strongly C-shaped curved ( Fig. 84 ). Pronotum with a yellowish shield. Spiracles ( Fig. 86 ) bicameral, air tubes with eight to ten annuli on the prothorax and six to eight on the abdomen, 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. 85 ) with eleven prns of unequal length (prns 1 —short, prns 6 —very 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, other—medially. Meso- (Th2) and metathorax (Th3) ( Fig. 85 ) 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 very long as, three ss (long, very short and minute), one long eps, one long ps and two eus (short and minute). Pedal lobe with five pda different in length: pda 2 and pda 4 very long, pda 1 long, about 2/3 as long as pda 1, pda 3 very short and fine, pda 5 minute and located close to the anterior edge of the segment. Abdominal segments I–VIII (Ab1–8) ( Fig. 85 ) 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, very 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. 87 ) with six fine setae dorsally (ds), two ps (long and short) and two sts. Abdominal segment X (Ab10) with two setae.

Head capsule ( Figs. 84 , 89 ) brownish yellow, strongly sclerotized, suboval. Endocarinal line about 2/3 as long as frons. Frontal sutures distinct, extending to antennae. One stemma (st) present close to antenna. Dorsal setae (five des): des 1 and des 2 medium, des 3 and des 5 long, des 4 fine and short; des 1 and des 2 located near to middle part of epicranium, des 3 —close to frontal suture, des 4 —on laterally of des 3, des 5 —anterolaterally. There is one dorsal sensillum between des 4 and des 5. Frontal area with four fs: fs 1 and fs 3 minute, fs 2 absent, fs 4 and fs 5 very long, and with two sensilla—one is between fs 1 and fs 3, the other is between fs 3 and fs 4 slightly displaced towards the frontal suture. Lateral setae: les 1 medium, about 3/5 as long as les 2, les 2 very long, as long as des 5. Ventral setae: vcs 1 as long as les 1, vcs 2 slightly shorter than vcs 1. 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. 90 , 106 ) is one-segmented, consisting of a basal membranous segment bearing an elongated porous sensorium (se) and seven sensilla: one ampullacea (sa), four styloconium (ss) and two basiconicum (sb).

Clypeus and mouthparts. Clypeus ( Fig. 91 ) trapezium - shaped, with two cls placed close to anterior margin of frons, cls 1 slightly longer than cls 2, and with one clypeal sensillum (clss) located between them. Labrum ( Fig. 91 ) with three lrs: lrs 1 and lrs 2 almost equal length, lrs 3 about 1/2 as long as lrs 1. Epipharynx ( Fig. 92 ) with two fine ams (ams 2 less 1/2 as long as ams 1), three finger-like als, and two short and stout mes. Labral rods (lr) moderately long, gradually narrowing and slightly converging posteriorly. One sensillum located on both sides of lr and four sensilla (esc) combined in two clusters with two pores in each. Mandibles ( Fig. 93 ) strongly sclerotized, triangular, with two apical teeth, mds 1 and mds 2 medium, slightly different in length, present one mandibular sensillum. Maxilla ( Fig. 94 ) with one very long stps, two long pfs (pfs 2 about 2/3 as long as pfs 1), very short mbs and three sensilla. Mala on the dorsal side with a row of five finger-like dms (one specimen from Kazakhstan have six dms, see remarks), on the ventral side with five thin acuminate vms (three comparatively long and two comparatively short). Maxillary palpi consist of two palpomere: basal palpomere transverse, with one short mxps and two sensilla, distal—elongated, 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 long 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 and pms 3 — short, subequal length, 1/3 as long as pms 2, pms 2 — very long.

Redescription of pupa. Figs. 95–97 .

Measurements (in mm). Body length: 3.15–3.89 (mean 3.52). Body width: 1.33–1.56 (mean 1.42). Head width: 0.56–0.58 (mean 0.57).

Coloration. From yellowish white to brownish yellow.

Body. Rostrum long and slender, 4.1–4.5x as long as wide in male, and 4.8–5.2x in female. Pronotum transverse, 1.2–1.3x as wide as long. Prothoracic depressions (pd) well defined, partially covered with antennae. Spiracles well developed on Ab1–5, and vestigial on Ab6.

Chaetotaxy. Setae from short to long, from slightly curved to straight, brownish yellow. Head capsule with one short, straight and rather stout vs, 1/2 as long as the width of rostrum at the base, and in addition with one os and one sos, both very slender and inconspicuous. Rostrum without setae. Pronotum (Th1) with one as, two ds, two sls, and three pls; all setae, except for pls 1–3, of approximately equal length, almost straight or slightly curved, pls 1–3 slightly shorter than others, curved. As and sls 1–2 located subapically on the small convex tubercles; ds 1 located subapically on anterior surface of the rather large pointed tubercle; ds 2 and pls 1–3 located at the bases of small, sharply pointed tubercles. Femora without fes. Meso- (Th2) and metanotum (Th3) with three medium - size dorsal setae (d), located apically on the small flat tubercles; the length of the setae gradually decreases towards the middle line. Abdominal tergites (Ab1–8) with three distinct dorsal setae (d), the length of the setae decreases towards the middle line, d 3 on Ab5 - 8 located at the bases of pointed tubercles, the size of the tubercles gradually increases towards the apex of the abdomen. There are minute and inconspicuous setae between d 1 and d 2 and between d 2 and d 3. Lt 1 minute, on Ab1–5 located on the small flat tubercles, on Ab5–7—near the base of small sharply pointed tubercles; lt 2 long, located near the bases of spiniform tubercles, which become gradually larger and more pointed posteriorly; ls absent. Urogomphi paired, sclerotized, elongated, straight, located close together throughout their length, with one very fine and short ventral setae (v).

Biology. Oligophagous on Rosaceae : Fragaria , Rubus , Rosa , Geum ( Scherf 1964; Dieckmann 1968).

Remarks. The larva of this species was described ( Ahmad & Burke 1972) from a single specimen, which had an unequal number prst —nine long and two short on one side of prothorax, while eight long and two short on the other. On the material I studied, this species has eleven prst (i.e. nine long and two short) on each side. In addition, I found a number of contradictions with the previous description, which prompted me to make a full redescription of the larva and pupa of this species.

I was particularly interested in the number of dms and vms on the mala of the maxilla, since these setae can be very useful in determining species. It was found that all larvae from Ukraine and Russia collected on Rubus have 5 dms and 5 vms, which does not coincide with the data of Ahmad and Burke, who indicate 6 dms and 5 vms. I studied additional material from Kazakhstan that was collected on the same host plant ( Rosa ) as the material in the work of Ahmad and Burke. Of the three prepared larvae, two had 5 dms and 5 vms, but one had distinctly 6 dms and 5 vms. Although I am not completely sure about the species identity of the material from Kazakhstan, it seems that this species can have a variable number of dms.

Figures

FIGURES 84–88. Anthonomus rubi, mature larva. 84—habitus of the body and frontal view of head, 85—thoracic spiracle, 86—lateral view of thoracic segments, 87—lateral view of abdominal segment I, 88—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 89–94. Anthonomus rubi, mature larva head and mouthparts. 89—head, frontal view, 90—antenna, 91—clypeus and labrum, 92—epipharynx, 93—left mandible, 94—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 95–97. Anthonomus rubi, pupa habitus and chaetotaxy. 95—ventral view, 96—dorsal view, 97—lateral view (Th1– 3—number of thoracic segments, Ab1–9—number of abdominal segments, sp—spiracle, pd—prothoracic depression; setae: as—apical, d—dorsal, ds—discal, lt—laterotergal, os—orbital, pls—posterolateral, sls—superlateral, sos—superorbital, v— ventral, vs—vertical).

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.