Opisthoscelis Schrader

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 : 5-6

Opisthoscelis Schrader

Opisthoscelis Schrader 1863: 7. Type species: Opisthoscelis subrotunda Schrader 1863, subsequently designated by Fernald 1903: 46.

Ophistocelis ; Signoret 1868: 525. Misspelling of genus name

Ophiscelis ; Signoret 1869a: 834. Misspelling of genus name.

Opliscelis ; Signoret 1869a: 855, 872. Misspelling of genus name.

Ophistoscelis ; Signoret 1869b: 100. Misspelling of genus name.

Generic diagnosis. Adult female and associated gall.

Galls on leaves; each typically globular, conical or hemispherical, rarely pit-like; with small circular, slit-like or fissured orifice/opening often on adaxial (upper) surface, but surface often difficult to determine in mature isobilateral leaves and galls typically opening on same surface on any one leaf. Body outline circular to elliptical; dorsum usually smaller than venter, especially at maturity, with whole of dorsum, a sclerotised part of it, or abdominal apex plugging gall orifice; body of mature female usually tightly fitting gall cavity. Abdomen not tapered. Vulva and anal opening ventral on posterior abdomen, with vulva between abdominal segments VII and VIII. Eyes on margin or dorsad of it. Antennae reduced, with ≤ 7 segments, segmentation often indistinct. Pair of broad frontal lobes posteromedial of antennae. Oral lobes membranous to sclerotic, often forming large circular pad around mouthparts. Tentorial box with aliform anterior extensions. Fore and mid legs varying from well developed to highly reduced, with some segmentation always apparent. Hind legs, on posterior of metathorax, sometimes appearing to be on anterior abdomen, large, always well developed, often elongate; ratio of length of trochanter + femur / length of tibia + tarsus approximately = 1:1; tibia-femur articulation functional; translucent pores present on at least tibia; trochanter with 2 or 3 campaniform sensilla on each side; claw digitules and tarsal digitules either well developed or highly reduced to absent. Anal opening surrounded by anal ring with ≥ 6 (range 6-20) setae; anal ring may be invaginated. Posterior abdominal segments usually with marginal fleshy projections (absent in Opisthoscelis thurgoona sp. n. and Opisthoscelis tuberculata sp. n.), each projection bearing spines or with a blunt sclerotic point. Marginal fringe of enlarged setae usually present (absent in Opisthoscelis serrata ). Dorsal setae bristle-like to flagellate, minute to large, 4-148 µm long (stout conical setae present in Opisthoscelis subrotunda ). Cribriform plates or tight clusters of tubular ducts either present or absent on dorsum. Microtubular ducts usually absent (present in Opisthoscelis ungulifinis sp. n.). Dorsal quinquelocular pores absent. Venter with macrotubular ducts present or absent; if present, with vestibule thin and sclerotic. Quinquelocular pores present on venter, at least around vulva and spiracles.

Adult male.

Antenna 10-segmented. Abdomen not elongated. Gland pouches present, each with pair of setae.

First-instar nymph.

Anterior margin of head incised at midline. Each spiracle with one trilocular pore next to opening. One submedial longitudinal row of dorsal setae on each side of body. Antennae 4-segmented, with 4 fleshy setae on apical segments.

Etymology.

The genus name is a Latinised combination of the Greek words opisthen, meaning behind, and skelos, meaning leg, and clearly refers to the long hind legs of the adult female because Schrader (1863: 6) diagnosed Opisthoscelis with one brief statement: "Where they have only two long posterior legs." The name Opisthoscelis is treated as feminine.