Opisthoscelis thurgoona Hardy & Gullan

Hardy, Nate B. & Gullan, Penny J., 2010, Australian gall-inducing scale insects on Eucalyptus: revision of Opisthoscelis Schrader (Coccoidea, Eriococcidae) and descriptions of a new genus and nine new species, ZooKeys 58, pp. 1-74 : 13-15

Opisthoscelis thurgoona Hardy & Gullan sp. n. Figs 1j8

Gall

(Fig. 1j). Female. On leaf. Immature gall (housing yellow nymph with a red dorsal “keel”) shallowly conical to hemispherical on orifice side (Fig. 1j), with gall surface whitish green to reddish; almost hemispherical on opposite side of leaf, tissue reddish green with distinct oil glands on surface. Gall height on orifice side ca 1 mm, ca 3 mm on opposite side, width 4-6 mm. Gall opening on either abaxial or adaxial leaf surface, slit-like, 0.5-1.0 mm long. Mature gall with tissue surrounding orifice brown and necrotic.

Male. Not known.

Adult female

(Fig. 8) (n = 6). Body ovate, length 2.1-3.4 mm, greatest width 1.5-2.8 mm; margin without lobes or indentations. Eyes on margin, each 38-55 µm wide. Antennae well developed, 7-segmented; each antenna 530-890 mm long; segment I with ca 3 hair-like setae; II with 5-9 hair-like setae; III with 4-8 hair-like setae; IV 4-6 hair-like setae; V with 1-4 hair-like setae; VI with 3 or 4 hair-like setae + 1 fleshy seta; VII with ca 6 hair-like setae + 3 fleshy setae. Frontal lobes each 300-310 µm long, 125-220 µm wide. Tentorial box 200-300 mm long; labium 80-150 mm long, 95-170 mm wide; pump chamber 15 µm long, 15-16 µm wide. Spiracles 100-130 mm long, 50-73 mm wide across atrium. All legs well developed, hind legs larger than fore or mid legs: fore leg with coxa 230-360 µm long, trochanter + femur 345-530 µm long, tibia 235-400 µm long, tarsus 100-140 µm long; mid leg with coxa 310-430 µm long, trochanter + femur 370-580 µm long, tibia 260-450 µm long, tarsus 110-150 µm long; hind leg with coxa 350-500 µm long, trochanter + femur 460-670 µm long, tibia slightly curved, outer margin concave, 380-580 µm long, tarsus 150-240 µm long; each leg with claw 23-40 µm long; translucent pores dense on hind tarsus and tibia, a few scattered on distal portion of femur; femur-tibia articulation functional; tarsal and claw digitules distinctly expanded at apices. Anal opening 65-84 µm wide, on ventral body surface, surrounded by sclerotic anal ring 85-104 µm wide bearing 14-18 setae, base of each seta surrounded by small pores.

Dorsum. Delineated by fringe of elongate setae, each seta 50-180 long, with blunt to truncate apex. Derm membranous. Dorsal setae minute, 5-9 mm long, scattered. Macrotubular ducts in two forms: (i) singly or in clusters of 2-8 ducts, cuticle of each cluster variously sclerotic, each duct short, ca 5 µm long, inner ductule not detected, scattered over dorsum, dense on head, posterior abdominal segments and margin of anterior abdominal segments and thorax; and (ii) single, larger ducts, 14-16 mm long, with dermal orifice with a rim 3.5-5.0 mm wide, scattered over dorsum, scarce or absent from posterior abdominal segments. Microtubular ducts absent. Quinquelocular pores absent.

Venter. Oral lobes membranous. Setae 13-103 mm long, in a transverse row across each abdominal segment, scattered along margin of head and thorax, on medial areas of meso- and metathorax, and a transverse band of elongate (up to 170 µm long) setae posterior of frontal lobes. Macrotubular ducts with distal (near vestibule) end of shaft constricted, about same size as larger ducts on dorsum. Quinquelocular pores 5 µm in diameter, overlapping in distribution with ventral setae, with a cluster around each spiracle, but most dense medially on posterior abdominal segments.

Material examined.

Holotype of Opisthoscelis thurgoona (here designated): AUSTRALIA: New South Wales: 1 adult female (3.4 mm long, 2.8 mm wide):ex leaf gall, Eucalyptus melliodora , 2 km NE of Thurgoona, Ettamogah Road, -36.03°; 146.98°, 8 Feb., 2004, PJG (ANIC).

Paratypes: AUSTRALIA: New South Wales: 2 adult females: same data as holotype, NH104, LGC00101 (ANIC); 14 adult females, 1 second-instar female, 27 first-instar nymphs: ex galls on leaves, Eucalyptus melliodora , 1 km N of Thurgoona, Table Top Road, -36.05°; 146.98°, 30 Dec., 1991, PJG (ANIC, except 1 adult female in BMNH, 1 adult female in USNM).

Comments.

Adult females of Opisthoscelis thurgoona are unusual amongst Opisthoscelis and Tanyscelis species in having each leg well developed, and 7 clearly separate antennal segments. These features, in combination with the ventral anal opening, with a sclerotic anal ring bearing numerous setae, each of which is surrounded at the base by a number of minute pores, give the adult female of Opisthoscelis thurgoona the resemblance of a species of Lachnodius . Morphological clues of the closer relationship between Opisthoscelis thurgoona and the other Opisthoscelis species (recovered by analysis of DNA sequence data (NBH, unpublished data)) are the presence of macrotubular duct clusters on the dorsum (possibly homologous to the cribriform plates found in Opisthoscelis subrotunda and Opisthoscelis beardlseyi ) and only 4 fleshy setae on each antenna (5 on species of Lachnodius ). Opisthoscelis thurgoona is known only from a single roadside location, 1 km north of Thurgoona near Albury in New South Wales. Opisthoscelis thurgoona is most similar to Opisthoscelis tuberculata (described as new below) and the two species are compared under the comments for the latter.

Live eggs of Opisthoscelis thurgoona are laid in the gall cavity and are pink to orange in colour, whereas newly hatched first-instar nymphs are orange. The chromosome number is 2n = 18 (LGC, unpublished data).

Etymology.

The species name is taken from the type locality. It is a noun in apposition.