Platycoelostoma Morrison

Platycoelostoma Morrison, in Morrison & Morrison, 1923: 34.

Type species: Coelostoma compressum Maskell, 1892, by designation of Morrison in Morrison & Morrison, (1923) and by monotypy.

Generic diagnosis. Information on the adult females and immatures instars of Platycoelostoma compressa can be found in Gullan & Sjaarda (2001), Morales (1991) and Morrison & Morrison (1923).

Adult female (modified from Gullan & Sjaarda, 2001): body elongate-oval, 6.1–14 mm long, derm membranous, covered dorsally and ventrally with numerous multilocular pores and rather fewer hair-like setae; collared setae, hairs and spines absent. Multilocular pores mostly oval-elongate, rarely triangular or circular, present across all segments on both dorsum and venter, densest on abdomen; each pore with a large central area with 2–5 large inner loculi plus 6–16 outer loculi. Simple tubular pores on margin of posterior segments of abdomen present or absent. Hair-like setae scattered on head and thorax, and in rows across abdominal segments; longest setae ventromedially on head and thorax, and near coxae of legs. Eyepots submarginal, close to antennal base. Antennae 9 or 10 segmented; all segments with long hair-like setae; segments III to X also with fleshy setae; a campaniform sensillum present dorsally on segment II. Mouthparts atrophied. Legs well developed, trochanter with 4–7 campaniform sensilla on each side, and a long ventral trochanteral seta; tibia and tarsus with many short setae ventrally; tarsus distinctly curved; claw broad at base, tapering, long, curved, without a denticle; with 2 slender claw digitules reaching apex of claw. Thoracic spiracles each with 20–80 multilocular disc-pores in expanded atrium. Abdomen with 8 pairs of spiracles, each with multilocular pores in atrium, except poorly developed posterior pair which lacks atrial pores in P. compressa (Maskell) and P. tasmanicum Gullan & Sjaarda; each spiracle elongate and divided into 3 distinct parts. Vulvar opening a transverse fissure, with 2 apodemes at each extremity. Cicatrices absent. Anal opening apical to subapical or ventral. Anal tube simple but sclerotised, lacking typical sclerotised ring at inner end, and without setae or pores.