Eriococcus aceris (Signoret)

Hodgson, Chris & Trencheva, Katia, 2008, A new species of Eriococcus (Hemiptera: Sternorrhyncha: Coccoidea: Eriococcidae) and redescriptions of Eriococcus roboris Goux and E. thymelaeae Newstead, with a key to the Eriococcus species on Quercus in the western Palaearctic, Zootaxa 1959 (1), pp. 1-38 : 27-31

Eriococcus aceris (Signoret)

Acanthococcus aceris Signoret, 1875: 35 .

Eriococcus aceris (Signoret) ; Cockerell, 1896:323.

Nidularia aceris (Signoret) : Lindinger, 1933: 108.

Note: although the type material appears to be lost, it is generally considered that its identity is known and that the description made by Williams (1985: 358) can be taken to describe the adult female.

Distribution. E. aceris appears to be restricted to the western Palaearctic as far east as Turkmenistan. It has a fairly wide host range, having been recorded off Aceraceae , Carpinaceae , Elaeagnaceae , Fagaceae (including Quercus pubescens ( Marotta & Tranfaglia, 1990) and Q. robur ( Hoy, 1963)) , Hippocastanaceae , Platanaceae , Rosaceae , Salicaceae and Ulmaceae ( Miller & Gimpel, 2000) .

Material studied. Italy, Padova , on Acer campestris , 20.v.1984, G. Pellizzarri ( DEAE): 2/6 adff in fair to good condition; also as previous but collected -. vi.1984 ( DEAE): 2/7 1st-instar nymphs in fair to good condition .

Adult female ( Fig. 11 )

Instar diagnosis. Adult female broadly oval, largest specimens 3.75 mm long, 2.2 mm wide. Dorsum strongly nodulose; with spinose setae of two sizes; macrotubular ducts of one size frequent; microtubular ducts frequent. Anal lobes protruding, about twice as long as wide, apically rounded, moderately sclerotised with inner margins conspicuously nodulose. Median (dorsal) plate triangular, lightly sclerotised, strongly nodulose. Venter with mainly flagellate setae; macrotubular ducts of 3 sizes, smallest medially; quinquelocular pores frequent; cruciform pores in a wide submarginal band. Microtubular ducts absent. Antennae 6 or 7 segmented. Frontal lobes present. Legs normal and well developed; coxa without translucent pores. Labium 3 segmented. Anal ring with 8 setae (after Williams, 1985).

Comment. The differences between adult female E. aceris and the other species discussed in this paper are given below in the key.

First-instar nymph ( Fig. 12 ). Described from 3 specimens off Acer campestris in fair to good condition.

Instar diagnosis. Oval in outline, rather more pointed posteriorly, 410–450 µm long, dorsum 165–175 µm wide (venter wider); anal lobes short but with 3 pairs of truncate spinose setae dorsally in addition to long flagellate apical seta; median plate not detected. Antennae 6 segmented. Dorsal microtubular ducts present, each outer orifice with two large wing-like extensions; quinquelocular pores present ventrally on head, thorax and abdomen; cruciform pores present submarginally on thorax; marginal and dorsal setae mostly spinose and truncate, each with a straight sides converging to a sharp point; submedial setae on abdomen all very short with more or less parallel sides; dorsal spinose setae in 4 longitudinal lines; claw with a well-developed denticle.

Dorsum. Derm membranous and nodulose. Dorsal setae mostly spinose, each subequal in size, coneshaped with straight sides converging on a sharp apex; each 23–27 µm long; with pairs of large setae on all segments medially and submedially on each thoracic segment and abdominal segment I, none present submedially on head; also with a line of very small setae, each about 2–3 µm long (shorter than width of basal socket), submedially on abdominal segments II–VII. Marginal setae similar to large spinose setae medially on dorsum, with about 21 on each side. Dorsal microtubular ducts, each with a long dark outer ductule about 6.5–7.0 µm long, and a large outer orifice with two wing-like extensions; sparsely distributed submedially on abdomen (1 pair per segment) and submarginally and submedially on thorax and head. Other pores absent. Anal lobes short, each about 23 µm long, barely sclerotised, with (on dorsal surface) two spinose setae on inner margin (anterior about 28–30 µm long, posterior about 12–14 µm long), a long flagellate apical seta about 150–165 µm long, and a spinose seta on outer margin about 16–18 µm long. Anal ring with 6 setae, each about 40–50 µm long.

Venter. Derm membranous. Setae: spinose setae, similar to those on dorsum but slightly smaller, in a group of 4 on anterior margin of head, each about 15 µm long; with a pair of rather spinose flagellate setae between antennae, each 16–23 µm long + 2 other flagellate setae more posteriorly; also with setose setae anteromedially to each meso- and metacoxa; and also medially on abdominal segments II and III, and medially and submedially on abdominal segments IV–VII; short submarginal setae present on most thoracic and abdominal segments; suranal setae about 21–27 µm long; ventral seta on each anal lobe about 26–38 µm long. Preantennal pores: single pores present anterior to each scape; frontal lobes absent. Quinquelocular pores few, each about 4.5 µm wide, present on head, thorax and medially/submedially on abdomen. Cruciform pores, each about 3.5–4.0 µm wide, present submarginally on thorax, distribution uncertain but with 1 on each side of posterior spiracles. Eyespots each about 13–15 µm wide.

Antennae 6 segmented, each 100–115 µm long; scape with 4 setae, pedicel with 3 setae + campaniform sensillum, segment III with 2 or 3 flagellate setae, IV with 1 fleshy seta, V with 1 fleshy seta + 2 flagellate setae, and VI with 3 fleshy setae, and about 6 other setae, mainly flagellate, 3 particularly long, longest 55–60 µm long. Clypeolabral shield about 75–85 µm long; labium about 58–65 µm long, with 7 pairs of setae, 2 on basal segment and 4 on apical segment; stylet loop extending posteriorly to metacoxa. Spiracles: width peritremes each about 6.5–7.5 µm. Metathoracic legs: lengths (µm): coxa 40–45; trochanter + femur 65–80; tibia 37–40; tarsus 50–55; claw 17–19; without spinulae on anterior surfaces of any coxa; number of setae: coxa 6; trochanter 3 (longest about 35–40 µm); femur 5; tibia 4 (tibial spurs setose but 20–23 µm long); tarsus 5 or 6. Tarsal digitules both capitate and subequal to length of claw; claw digitules slightly longer than claw and both slightly capitate; claw with a distinct denticle.

Comment. The first-instar nymph of E. aceris is easily separable from that of E. melnikensis and E. roboris because all the dorsal spinose setae forming the double mid-line are sharply pointed and subequal in size. Those of E. melnikensis and E. roboris are basically of two sizes, those on abdominal segments II–V being small to minute, and all spines are truncate rather than sharply pointed. In addition, the 1st-instar nymph of E. aceris lacks spinose seta submedially on the head, whereas one is present on each side on E. melnikensis and E. roboris .

Figures

FIGURE 11. Adult female Eriococcus aceris (Signoret) (slightly modified after Williams, 1985). For labels, see Fig. 1.

FIGURE 12. Second-instar female Eriococcus aceris (Signoret). For labels, see Fig. 1.