Eriococcus thymelaeae Newstead

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 : 31-36

Eriococcus thymelaeae Newstead

Eriococcus thymelaeae Newstead, 1897: 102 .

Nidularia thymelaeae (Newstead) : Lindinger, 1935: 135

Acanthococcus thymelaeae (Newstead) : Kozár & Walter, 1985: 74.

Distribution. E. thymelaeae is currently known from Algeria, Egypt, Israel, Morocco and Spain, off Rutaceae and Thymeleaceae ( Miller & Gimpel, 2000). The additional records below add Greece and Cyprus to the localities, and Fagaceae and Rosaceae to the host families. This species has not been redescribed in detail since that of Newstead, 1897 ( Miller & Gimpel, 2000). Type material not seen during this study.

Material studied: GREECE, Vonilsa, on Quercus coccifera , 17.vii.2000, Fontana ( DEAE): 1/1 adf in good condition. Also: CYPRUS, Kyrenia, on Poterium spinosum (Rosaceae) , 1.i.1932, E.E. Green ( BMNH): 3/6adff + 1 2nd-instar female.

ADULT FEMALE ( Fig. 13 ). Described from 1 specimen off Quercus in good condition + 3 specimens off Poterium in fair to good condition .

Instar diagnosis. Roundly oval, 1.37–2.13 mm long; width 0.83–1.48 mm. Anal lobes sclerotised and well developed; median plate unsclerotised. Dorsum covered in sharply cone-shaped spinose setae; some along margin distinctly larger. Dorsum also with numerous macrotubular ducts (of one size) and small microtubular ducts; venter with similar microtubular ducts along margin and 3 sizes of macrotubular ducts, largest and median size restricted to near margin, smallest duct medially throughout. Quinquelocular pores abundant on abdomen, less frequent more anteriorly; cruciform pores sparse submarginally on anterior abdominal segments and thorax but also medially on head. Legs relatively well developed; metacoxae and metafemur with minute sclerotised pores; claws with a strong denticle. Antennae 7 segmented; frontal lobes present but obscure on available specimens.

Dorsum. Derm membranous. Dorsal setae all spinose, of approximately one size, each with a quite broad base and more or less straight sides, narrowing to rather pointed, rounded apex; each with a narrow basal socket and 13–46 µm long (mostly about 25 µm), longer on margin; present throughout although in distinct segmental bands on abdomen; with on each segment medially: VIII 0; VII 4–7 , VI 9–15 , V 18–21 , IV 27 . Dorsal pores absent. Dorsal ducts of two types: (i) macrotubular ducts, each quite large, outer ductule broad, about 16–25 µm long, each with faint elongate inner ridges; cup-shaped invagination symmetrical, about 10–12 µm wide, less than width of basal socket of dorsal spinose setae (13–17 µm wide); inner ductule often obscure, narrow, widening towards distal end; present throughout, about as abundant as dorsal spinose setae, and (ii) microtubular ducts, each very small, apparently composed of a sclerotised orifice, a short tube (3–4 µm long) and filamentous inner ductule; present throughout (also on dorsal surface of each anal lobe); about as abundant as macrotubular ducts. Anal lobes sclerotised throughout, finger like, each about 75–95 µm long along inner margin, 65 µm wide; inner margins not serrated or nodulated; dorsal surface with 3 spinose setae and a long apical hair-like seta: anterior inner margin seta rather narrow, about 38–45 µm long; posterior inner margin seta rather narrow about 40–60 µm long; outer margin seta stouter, about 40–60 µm long; apical setose seta 280–320 µm long. Median plate unsclerotised, with 3 small lobes posteriorly, length 16–26 µm, width 58–60 µm. Anal ring 55–62 µm wide, with 4 pairs of long setae, each about 108–135 µm long; with a row of cone-shaped pores .

Margin. Not demarcated but probably represented by larger spines, at least on abdomen, each up to 60 µm long, each rather blunter than those on dorsum; most abdominal segments with 2 large setae.

Venter. Membranous except anal lobes sclerotised; short sclerotised bar extending 40-50 µm anteriorly from each basal seta. Ventral setae mainly setose, most about 28–40 µm long, but some up to 58–75 µm long; most abundant anteriorly between antennae and clypeolabral shield (with about 8–10 pairs of flagellate setae), and medially on posterior 5 or 6 abdominal segments (no. setae across each segment: II 4 medially + 2 pairs laterally, III 8–12 , IV 9–12 , V 10–13 , VI 9 or 10, VII 7–9 , and VIII 4–6 ); also with sparse groups mesad to each coxa; spinose setae, similar to those on dorsum but perhaps slightly smaller, extending ventrally as far as eyespot on head and along submargins, with two on most abdominal segments, 1 similar to dorsal setae in size and shape, each about 25 µm long, and other slightly larger and usually more pointed, each 30–40 µm long. Ventral surface of each anal lobe with 2 setose setae, 1 near apex, about 90–110 µm long, 1 near base about 50–75 µm long; suranal setae on either side of anal ring each about 50–60 µm long. Ventral pores of three types: (i) quinquelocular pores, each about 5 µm wide; abundant in a segmental band on each posterior abdominal segment, becoming less abundant anteriorly and sparse medially on thorax and head; also present sparsely submarginally on abdominal segments, on head and associated with each spiracle; (ii) cruciform pores, each oval, about 5.0–5.5 µm long, and 3–4 µm wide, appearing to have a partially bilocular pore; in a sparse submarginally band from abdominal segments IV anteriorly onto head, where also present anterior to clypeolabral shield, and (iii) a preantennal pore present anterior to each scape. Ducts of 4 sizes present: (i) large macrotublar ducts, similar to those on dorsum (each with cup-shaped invagination about 10–11 µm wide, outer ductule about 20–25 µm long), in a narrow submarginal band, those more ventral tending to be smaller, becoming type (ii) ducts, so with a cup-shaped invagination about 7–8 µm wide and outer ductule 20–25 µm long; extending a short distance onto venter; (iii) small macrotubular ducts, each with an asymmetric cup-shaped invagination about 5–6 µm wide and outer ductule about 20 µm long; present sparsely throughout; and (iv) microtubular ducts similar to those on dorsum, but restricted to a sparse submarginal band .

Eyespots distinctly displaced ventrally from margin, each lens 22–25 µm wide (socket 33–40 µm wide). Antennae each 7 segmented, about 255–280 µm long; setae: scape 4, pedicel 2 + a campaniform sensillum; III 0; IV 3 setose setae; V 1 fleshy seta; VI with 1 fleshy seta + 3 setose setae; and VII with 3 stout fleshy setae and 7 stiff setae; each antenna with a membranous, non-expanded, frontal lobe. Clypeolabral shield about 140–165 µm long; labium about 140–155 µm long, 3 segmented, basal segment with 2 pairs of setae (1 unusually long), middle segment 1 pair and apical segment with 5 pairs of setae; length of stylet loop unknown. Spiracles quite small, width of peritremes 28–35 µm. Legs well developed; lengths (µm) of metathoracic legs: coxa 175–185; trochanter + femur 245–250; tibia 160–200; tarsus 155–160; all coxae with a few spinules on anterior surfaces, fewest on procoxae; metacoxa with minute sclerotised pores on outer posterior margin, extending round onto anterior surface, with a total of about 12–34; these pores also present on dorsal surface of femur, where 3–6 pores present; each coxa with 5 setae; each trochanter with 2 long setae (longest about 83 µm) + 1 short seta; each femur with 4 or 5 setae; each tibia with 5 setae, and each tarsus with 6 or 7 setae; tarsal campaniform sensillum present; tarsal digitules with relatively narrow apices, subequal to or slightly longer than claw; claw about 35–38 µm long, with a distinct denticle; claw digitules capitate and longer than claw. Vulva structure unclear.

Comment. The two lots of material discussed above were very similar, differing in only a few particulars, with that from Cyprus tending to have more macrotubular ducts on the dorsum and fewer coxal pores. It agrees quite closely with the description of Kozár (pers. comm.) made from a type specimen .

The adult female of E. thymelaeae looks very similar to that of E. devoniensis (Green) , although the latter has not been recorded off Fagaceae yet. E. thymelaeae differs in having (character-states on E. devoniensis in brackets): (i) different structured coxal pores — these are present on the metacoxa and metafemur of both species but, on E. thymelaeae , they are all similar in size and shape, and round in cross-section (See Fig. 13 ) (of variable size and shape, and, although concave, rather flat); (ii) 4–9 dorsal spinose setae present medially on abdominal segment VII (absent); (iii) dorsal spinose setae all rather similar in size, those medially not obviously larger than those elsewhere on dorsum (most segments with a pair of dorsal spinose setae medially about as large as marginal setae); (iv) smallest ventral tubular ducts frequent on abdominal segment VII (absent); (v) spinose setae on anal plates quite long and narrow (shorter and more similar to dorsal setae); (vi) dorsal spinose setae with a fairly pointed apex (more broadly conical, with a distinctly truncated apex); (vii) antennal segments V, VI & VII together much shorter than segments III + IV (subequal); (viii) quinquelocular pores much less frequent submarginally than medially on abdominal segments (abundant across the full width of abdominal segments), and (ix) marginal spinose setae up to 60 µm long (largest about 40 µm). In addition, the microtubular ducts are much smaller on E. devoniensis .

Second-instar female ( Fig. 14 ). Described from 1 specimen off Poterium in rather poor condition, particularly anteriorly.

Instar diagnosis. Roundly oval, 1.01 mm long; total width 0.83, dorsum 0.47 mm. Anal lobes lightly sclerotised and well developed; median plate not detected. Dorsum probably with 4 longitudinal lines of small spinose setae, two medially and two submedially; marginal setae strongly spinose. Dorsum also with no macrotubular ducts but with a few minute microtubular ducts; venter without macrotubular or microtubular ducts. Loculate pores restricted to venter, mainly trilocular, but a few quinquelocular, sparse throughout; cruciform pores few, present submarginally. Legs relatively well developed; claws with a strong denticle. Antennae 6 segmented; frontal lobes not detected.

Dorsum. Derm membranous. Dorsal setae all small and spinose, of approximately one size, each conical, often slightly bent, with a sharply rounded tip; basal socket distinctly wider than base of seta; each about 6–8 µm long; exact distribution unclear but probably in 4 elongate lines, two medially and two submedially, with 4 per segment on abdomen, less clear anteriorly. Dorsal ducts: macrotubular ducts absent; microtubular ducts very small, exact structure unclear; sparse throughout. Anal lobes barely sclerotised, almost triangular, each about 45 µm long along inner margin, and 40 µm wide; inner margins not serrated or nodulated; dorsal surface with 3 spinose setae and a long apical seta: anterior inner margin seta rather narrow, about 23–25 µm long; posterior inner margin seta rather narrow, about 26–28 µm long; outer margin seta stouter, about 28–30 µm long; apical setose seta about 250 µm long. Median plate not detected. Anal ring about 40 µm wide, with 3 pairs of long setae, each about 85 µm long; with a row of cone-shaped pores.

Margin. Not demarcated but represented by largest spinose setae, often slightly curved with a sharp rounded apex, each up to 33 µm long; abdominal segments with 2 setae, 1 slightly larger than other (smaller up to about 27 µm long.

Venter. Membranous. Ventral setae mainly setose, most abundant anteriorly between antennae and clypeolabral shield (with probably 4 pairs of flagellate setae), longest about 33–35 µm long; each abdominal segment with 2 or 3 pairs of setae; with 1 long seta mesad of each meso- and metacoxa, plus two shorter setae; spinose setae, similar to those on margin but distinctly smaller, in a submarginal line (each 16–20 µm long). Ventral surface of each anal lobe with 2 setose setae, 1 near apex, about 60 µm long, 1 near base about 40 µm long; suranal setae on either side of anal ring each about 40 µm long. Ventral pores of two types: (i) loculate pores, mainly trilocular (when about 3 µm wide) but a few quinquelocular (each about 4.5 µm wide); sparse throughout but exact distribution uncertain; (ii) cruciform pores, each oval, about 5 µm long, and 3.5 µm wide, appearing to have a partially bilocular pore; with about 3 or 4 on each side of thorax and anterior abdominal segments but absent on head. Single preantennal pores present anterior to each scape. Macrotubular and microtubular ducts absent.

Eyespots distinctly displaced ventrally from margin, each lens 23 µm wide (socket 25 µm wide). Antennae each 6 segmented, about 163 µm long, setae: scape?4, pedicel 2 + a campaniform sensillum; III 2; IV 1 fleshy seta; V with 1 fleshy seta + 3 setose setae; and VI with 3 stout fleshy setae and an unknown number of other setae; frontal lobes not detected. Clypeolabral shield about 105 µm long; labium about 110 µm long, 3 segmented, with 2 pairs of setae on basal segment (inner pair quite long), 1 pair on segment II and 4 pairs of setae on apical segment; length of stylet loop unknown. Spiracles quite small, width of peritremes 16–18 µm. Legs: metathoracic leg lengths (µm): coxa 90–92; trochanter + femur 128–130; tibia 75; tarsus 93; meso- and metacoxae with a few spinules on anterior surfaces; metacoxa without coxal pores; number of setae: coxa 5, trochanter 2 long setae (longest about 30 µm) + 1 short seta; femur?5; tibia 3, and tarsus with 7; with a few spinulae on anterior surfaces of all coxae; tarsal campaniform sensillum present; tarsal digitules with relatively long narrow apices, subequal to or slightly longer than claw; claw about 27 µm long, with a distinct denticle; claw digitules roundly capitate and longer than claw.

Comment. This immature stage of E. thymelaeae differs from all the other 2nd-instar nymphs discussed here in lacking large dorsal spinose setae on the dorsum. In addition, most of the loculate pores are trilocular rather than quinquelocular.

General discussion. Frontal lobes and preantennal pores (frontal tubercles). In the present paper, we have used the term preantennal pore rather than frontal tubercle because of their small size. Williams (1985) defines these terms and discusses their occurrence. He states (1985, p. 349) "They are certainly present in many species of Eriococcidae and may have some taxonomic significance. In all species studied so far, frontal lobes and frontal tubercles never occur together and one may be derived from the other." On all the species described above, frontal lobes and frontal tubercles (preantennal pores) are present on the adult females and both second-instars. It does seem likely that these preantennal pores are homologous with those found in other families, such as the Coccidae .

Figures

FIGURE 13. Adult female Eriococcus thymelaeae Newstead. For labels, see Fig. 1, except apb = anal plate bar.

FIGURE 14. Second-instar Eriococcus thymelaeae Newstead. For labels, see Fig. 1.