Acanthoccus mariannae Pellizzari

Pellizzari, Giuseppina & Germain, Jean-François, 2010, A new species of Acanthococcus (Hemiptera, Coccoidea, Eriococcidae) on Leptospermum scoparium (Myrtaceae) from Italy and France, Zootaxa 2543, pp. 51-63 : 52-62

Acanthoccus mariannae Pellizzari sp. n.

Living specimens. Adult female elongate, oval, grey-brown; abdomen with distinct segmentation. Females settled on upper surface of leaves or on twigs of host plant. Before egg-laying, the adult females become enclosed in a felted, white, lightly convex eggsac, open only at anal end. Male test oval, white, on under surface of leaves (plate 2). Adult males winged.

Material studied: Holotype: adult female, Italy, Genova, 14 August 2004, on Leptospermum scoparium (Myrtaceae) , DEAE, slide n.1128/1.

Paratypes: Italy: same data as holotype: 12 adult females, 4 first-instar nymphs, 5 second-instar females, 5 second-instar males. Also prepupae, pupae and 2 adult males, not described in this paper, DEAE, 27 slides n.1128/2–1128/28. Also: France, Corsica, Ajaccio, 5 May 2006, on Leptospermum sp., LNPV, 16 adult females on 5 slides n. 0600432/1–0600432/5; France, Corsica, Olmeto, 29 September 2006, on Leptospermum sp., LNPV, 8 adult females on 2 slides n. 0602207/1–0602207/2; France, Corsica, Ajaccio, 19 February 2006 on Leptospermum , MNHN, 4 females on slide n. 14568.

ADULT FEMALE ( Fig. 1 ). Described from 9 young females in good condition. Details checked on remaining specimens. Length and width also from 4 post-reproductive females.

Mounted specimen. Body elongate oval, 1.60 (1.44–1.96) mm long, 0.76 (0.48–0.96) mm wide (Plate 1, fig. a). Post-reproductive female 2.16 (2.0–2.35) mm long and 1.14 (1.12–1.2) mm wide.

Margin. Marginal enlarged setae conical, with straight sides and blunt apex, each 18 (16–22) µm long and 6 µm wide at base, distributed along body margin, totalling 42-43 on each side; with 2 setae on margin of each abdominal segment, 4–5 setae on margin of each thoracic segment, and with row becoming double on dorsal apex of head.

Dorsum. Enlarged setae small, 5.0–6.5 µm long and 3-4 µm wide at base, distributed in an irregular row of 7–12 setae across each abdominal segment; also sparse on thorax and head. Dorsal macrotubular ducts large, each about 20 µm long and 10 µm wide, with a well-developed sclerotised rim and inner ductule; numbering 10–20 across each abdominal segment, becoming less abundant posteriorly, and sparse on head and thorax (Plate 1, fig.b). Microducts numerous, scattered, each 6.5 µm long. Anal lobes protruding, slightly sclerotised, each 67 (60–74) µm long, each lobe dorsally with 3 enlarged setae and 3 or 4 microtubular ducts; ventrally with 2 hairlike setae. Apical seta 120 µm (110–136) long (Plate 1, fig.d). Anal ring with 4 pairs of setae and with an outer row of cone-shaped pores. Cauda present, triangular in shape, with an irregular margin.

Venter. Labium 3-segmented, with 2 pairs of setae on unsclerotised basal segment, one pair on middle segment and 5 pairs on apical segment. Stylet loop slightly exceeding level of second coxae. Antennae 7- segmented; each antenna with a frontal lobe. Total length of each antenna 150 (140–160) µm. Scape with 3 setae, 2nd segment with 2 setae and 1 sensory pore, 3rd segment without setae, 4th segment with 2 setae, 5th segment with 1 fleshy seta, 6th segment with 1 fleshy seta + 2 setose setae, 7th segment with 3 fleshy setae + 7 flagellate or hair-like setae. Eyes near margin. Legs well developed; hind coxa with translucent pores and spinulae; trochanter with 2 campaniform pores; claw with small denticle. Tarsal digitules knobbed; claw digitules longer than claw, knobbed. Measurements of metathoracic leg: coxa 41 (40–46) µm; trochanter + femur 123 (106–136) µm; tibia 59 (50–68) µm; tarsus 89 (84–96) µm; claw 18 µm. Body setae: ventral setae hair-like, with 2 on median part of each abdominal segment, more numerous near coxae on thorax and on head. Minute hair-like setae sparse on abdominal segments. Loculate pores each quinquelocular and 3–4 µm wide, numerous, forming transverse bands on posterior abdominal segments, becoming less abundant anteriorly and sparse on head and on medial and submarginal parts of thorax; also with 2–6 laterad to each spiracle opening. Cruciform pores few, each 3–4 µm long, present on submargin of thorax and head. Macrotubular ducts smaller than dorsal ducts, each 18 µm long, 6 µm wide, mainly distributed along body margin and submarginally (Plate 1, fig.c). A few very small macrotubular ducts, each 11–16 µm long and 2.5 µm wide, with a sclerotised ring 4 µm in diameter and a very long inner filament, intermingled with quinquelocular pores on posterior abdominal segments. Spinules present on abdominal segments.

Comment. This new species differs from the other Eriococcus species living on Leptospermum by having the following combination of characters: 7-segmented antennae; dorsal enlarged setae markedly smaller than marginal setae; large dorsal macrotubular ducts with markedly symmetrical cups; and two sizes of ventral tubular ducts. The large dorsal macrotubular ducts are also clearly visible in the living adult female under a stereo microscope magnification (Plate 2, fig. f). According to the descriptions and drawings by Hoy (1954; 1959), both E. cultellus and E. campbelli have dorsal enlarged setae markedly smaller than the marginal setae, but the marginal setae are long and slender, and they have 6-segmented antennae. E. gibbus and E. milleri have 7-segmented antennae but the dorsal enlarged setae are as long as the marginal setae. Moreover, E. gibbus has the enlarged setae on the last abdominal segments with almost parallel sides and a blunt tip. E.

leptospermi has 6-segmented antennae and enlarged dorsal setae as long as the marginal setae. E. orariensis is clearly separated from the others by having the marginal setae only on the abdominal segments; in addition, the enlarged seta on the margin of the penultimate abdominal segment is stout, “peg-like”, with a blunt tip. E. spiniger is also clearly distinct due to the presence of about 70 enlarged marginal setae, on each body side, each with a blunt apex.

FIRST- INSTAR NYMPH ( Fig. 2 ). Described from 4 specimens in good condition.

Mounted material: oval, 0.4 mm long and 0.18 mm wide.

Margin. Marginal enlarged setae conical, with straight sides and a blunt apex, with 1 seta on each abdominal segment and a total of 22 or 23 on each body side, and with row becoming double dorsally on apex of head; each spine 9.5 µm long and 2.5 µm wide.

Dorsum. Dorsal spinose setae very small, about 2.5–3.0 µm long, in four longitudinal rows on thorax and abdomen. Microducts present submedially on abdomen, with one pair per segment, and with a few on thorax and head. Anal lobes moderately protruding, lightly sclerotised, each 21 µm long, with 2 enlarged setae dorsally and 2 hair-like setae ventrally; each apical seta 108 µm long. Anal ring with 6 setae. Cauda not located.

Venter. Labium 43–45 µm long, 3-segmented, with 2 pairs of setae on basal segment, 1 pair of setae on second segment and 5 pairs on apical segment; stylet loop reaching coxae of third legs. Antennae 6- segmented, each 83 (77–90) µm long, scape with 3 setae, 2nd segment with 3 setae and one sensory pore; 3rd segment with 2 setae; 4th segment with 1 fleshy seta; 5th segment with 1 fleshy + 2 flagellate setae; 6th with 3 fleshy + 5 flagellate setae. Legs well developed, 136–147 µm long. Claw 13 µm long, with a small denticle; tarsal and claw digitules slightly capitate and longer than claw. Body setae: with one pair of interantennal setae and two other pairs of setae between antennae and clypeolabral shield. Very short setae forming a longitudinal submarginal and a submedian row on each side of abdomen; with submarginal short setae present on thorax; with 1 pair of suranal setae plus 1 pair of ventral setae medially on each abdominal segment; other setae few on thorax. Loculate pores, each with 3 loculi, few, present on head and thorax plus 2 submedially across each abdominal segment. Cruciform pores: with 3 on each submargin of thorax. One preantennal pore present anterior of each scape.

SECOND-INSTAR FEMALE NYMPH ( Fig. 3 ). Described from 5 specimens in good condition.

Mounted material: body membranous, oval, 0.70 (0.88–0.64) mm long, 0.34 (0.30–0.40) mm wide.

Margin. Enlarged setae conical, each about 13 µm long and 5 µm wide, with straight sides and a blunt apex, totalling 34–35 on each side; with 2 setae on margin of each abdominal segment, 3 or 4 on each thoracic segment and with row becoming double on apex of head.

Dorsum. Dorsal conical setae very short, each 5 µm long and 1.5 µm wide, distributed in four longitudinal rows on thorax and abdomen, plus two spinose setae anteriorly on head. Microducts, each about 5 µm long, present submarginally and also sparsely throughout dorsum. Cauda observed in 2 specimens, subrectangular, with an irregular margin. Anal lobes lightly sclerotised, each 44 (42–48) µm long, with 3 enlarged setae and 2 microducts on dorsal surface, plus 2 hair-like setae on ventral surface. Apical seta each 104 (110–102) µm long. Anal ring with 6 setae.

Venter. Labium 3-segmented, with 2 pairs of short setae on unsclerotised basal segment, 1 pair on middle segment and 5 pairs on apical segment. Antennae 6 segmented, each 100 (97–106) µm long, each antenna with a frontal lobe; scape with 4 setae; 2nd segment with 3 setae + 1 pore; 3rd segment with 2 setae; 4th segment with 1 fleshy seta; 5th segment with 1 fleshy seta + 2 flagellate setae; 6th with 3 fleshy setae + 6–7 flagellate setae. Legs well developed. Length of metathoracic leg: coxa 28 (24–30) µm; trochanter + femur 63 (52–70) µm; tibia 31 (28–36) µm; tarsus 59 (56–64) µm; claw with a small denticle, each 15 µm long; tarsal and claw digitules slightly capitate and longer than claw. Trochanter with 2 pores. Body setae: with 5 pairs of setae on head between antennae and clypeolabial shield; with 1 pair of suranal setae and 1 pair of setae medially on each abdominal segment, plus submedial and submarginal rows of short setae on abdominal and thoracic segments. Quinquelocular pores mainly present submarginally on thorax and abdomen, with 1 pore on submargin of each abdominal segment, 1–3 pores near each stigmatic opening and 2 pores on head between antennae. A few cruciform pores present on margin of thorax. One preantennal pore present anterior to each scape. Spinules present on abdominal segments.

SECOND INSTAR MALE NYMPH ( Fig. 4 ). Described from 5 specimens in good condition.

Mounted material. Body membranous, oval, 0.57 (0.56–0.60) mm long, 0.26 (0.25-0.28) mm wide

Margin. With enlarged conical setae each 13 µm long and 5 µm wide, with straight sides and a blunt apex, totalling 34–36 on each side; with 2 setae on margin of each abdominal segment, 3–4 on each thoracic segment,. and with row becoming double on apex of head.

Dorsum. Dorsal conical setae very short, each 3 µm long and 1.5 µm wide, distributed in four longitudinal rows on abdomen and thorax, plus 2 spinose setae anteriorly on head. Macrotubular ducts each with a well-developed cup-shaped invagination, diameter 8 µm, sparse over dorsum. Microducts each about 5 µm long, present submarginally and also sparsely throughout dorsum. Cauda observed in 3 specimens, subrectangular, with an irregular margin. Anal lobes lightly sclerotised, each 41 (35–44) µm long, with 3 spinose setae and 2 microducts on dorsal surface, plus 2 hair-like setae on ventral surface. Apical setae each 93 (83–102) µm long. Anal ring with 6 setae.

Venter. Labium 3-segmented, with 2 pairs of setae on unsclerotised basal segment, 1 pair of setae on middle segment and 5 pairs of setae on apical segment. Antennae 7 segmented, each 99 (96–102) µm long, each antenna with a frontal lobe; scape with 4 setae; 2nd segment with 3 setae + 1 pore; 3rd segment without setae; 4th segment with 2 setae; 5th segment with 1 fleshy seta; 6th with 1 fleshy + 2 hair-like setae; 7th with 3 fleshy + 7 flagellate setae. Macrotubular ducts with a well-developed cup-shaped invagination and long inner ductule, smaller (diameter 5 µm) than dorsal ducts, mainly distributed on head and submargin of abdomen, these ducts intermingled with macrotubular ducts similar in size to those on dorsum (diameter 8 µm). Legs well developed. Lengths of metathoracic legs: coxa 26 (24–28) µm; trochanter + femur 68 (64–70) µm; tibia 31 (28–36) µm; tarsus 53 (50–56) µm; claw 14 µm, with a small denticle, tarsal and claw digitules slightly capitate and longer than claw. Trochanter with 2 pores. Body setae: with 4 pairs of hair-like setae between antennae and clypeolabral shield. With 1 pair of suranal setae and 1 pair of flagellate setae medially on each abdominal segment, plus submedial and submarginal rows of shorter setae on abdominal and thoracic segments. Other short setae few on head and thorax. Quinquelocular pores numbering 4 across each abdominal segment; also with a few on head (2 between antennae) and thorax, plus 2–4 pores near each stigmatic opening. A few cruciform pores present on margin of thorax. Spinules present on abdominal segments.

Comments on morphology of nymphal instars. The only description of nymphal stages of Eriococcus species living on Myrtaceae or on Leptospermum are those of Hoy on E. orariensis (1954, 1958). He described and illustrated the first instar ( Hoy, 1954) showing that, like the adult female, the marginal spines are only present on the abdominal segments. A subsequent paper, devoted to the immature stages of E. orariensis ( Hoy, 1958) , presents instar descriptions (somewhat unclear), with measurements and statistics, but without drawings. Instead, there is a plate with photos of all instars at different growing periods and a plate with photos of pores and tubular ducts. With regard to first instar morphology, the author points out the presence of trilocular pores, noticed also on the first instar of E. leptospermi but not observed “in the first nymphal stage of any other species of Eriococcus examined to date in New Zealand ” ( Hoy, 1958). Trilocular pores are present also on the first instar of A. mariannae but are 5 locular on other Palaearctic Eriococcus first instars (i.e. E. roboris Goux , E. melnikensis Hodgson & Trencheva , E. aceris (Signoret) ( Hodgson & Trencheva, 2008) .

With regard to second-instar female (“intermediate female”, according to Hoy, 1958), E. orariensis again has marginal setae only on the abdominal segments. In addition, it has the stout, dorsal “peg-like” seta with blunt tip each on each margin of the penultimate abdominal segment, as in the adult female. Although the distribution of ventral 5-locular pores is similar in E. orariensis and A. mariannae , the second-instar female of A. mariannae is clearly different in having enlarged marginal setae along the whole body margin.

The second-instar male of E. orariensis is characterised by a moderate number of dorsal tubular ducts whereas, on the venter, they are almost entirely 5-locular pores, whereas the macrotubular ducts are numerous on the dorsum of A. mariannae and are also present on the ventral margin and submargin of the body, mixed with smaller tubular ducts.

PLATE 1. a: microphoto of adult female of A. mariannae Pellizzari ; b: dorsal macrotubular ducts; c: ventral tubular ducts; d: adult female anal lobes.

Derivatio nominis. The species is named after my elder daughter Marianna, who came with me on several collecting trips.

PLATE 2. a: adult females of A. mariannae Pellizzari enclosed in a felt eggsac; b: male tests; c: infested Leptospermum scoparium ; d: nymphs on a Leptospermum twig; e: egg-laying female (ventral view); f: young adult female.

Biological notes. The young adult females and the ovipositing females, enclosed in their white felted eggsac, settle on the under surface of leaves, on the axil of leaves and twigs, and along the thin twigs of Leptospermum scoparium (Plate 2, fig. a). The oval, white, felted tests of the males are secreted on the underside of leaves or along the thin twigs (Plate 2, fig. b). In Italy, all instars (eggs, nymphal instars, adult males and females) were recorded on the host plant at the time of collection (Aug. 14, 2004) (Plate 2, fig. d). In France, adult females and males have been collected in May and again in September.

Despite the large number of known Acanthococcus or Eriococcus species, relatively few papers mention their biology or discuss how the number of annual generations varies depending also on the meteorological conditions. For instance, according to Gill (1993), E. araucariae develops 2 generations/year in California, whereas in South Italy it has 6 or 7 generations/year and overwinters as the egg stage ( Marotta et al., 2001). With regard to Eriococcus species living on Leptospermum , very little information is available. According to Zondag (1977), E. orariensis develops three and a partial fourth generations on Leptospermum scoparium in New Zealand. Although sparse, the collection data for A. mariannae suggest that this species could develop several overlapping generations throughout the year.

Figures

FIGURE 1. Acanthoccus mariannae Pellizzari, sp. n., adult female, where A: 5 - locular pore; B: cruciform pore; C: ventral tubular duct; D: ventral tubular duct; E: dorsal tubular duct; F: marginal enlarged seta; G: dorsal conical seta; H: microduct.

FIGURE 2. Acanthoccus mariannae Pellizzari, first instar nymph, where A: preantennal pore; B: antenna; C: cruciform pore; D: trilocular pore; E: ventral seta; F: microduct; G: marginal enlarged seta; H: dorsal conical seta.

FIGURE 3. Acanthoccus mariannae Pellizzari, second-instar female nymph, where A: 5 - locular pore; B: cruciform pore; C: ventral seta; D: marginal enlarged seta; E: dorsal conical seta; F: microduct.

FIGURE 4. Acanthoccus mariannae Pellizzari, second-instar male nymph, where A: tubular duct; B: 5 - locular pore; C: cruciform pore; D: ventral tubular duct; E: marginal enlarged seta; F: dorsal conical seta; G: dorsal tubular duct; H: microduct.