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Volume 70, 1940-41
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Genus Triacanthella Schaeffer, 1899.

Small, generally light-coloured forms with strongly-granulate cuticle and three large anal spines. Empodial appendage rudimentary. Ocelli and postantennal organ present.

Three species are known from New Zealand proper, and a fourth, T. alba, was described by Carpenter from the Auckland and Campbell Islands.

Key to the New Zealand Species of Triacanthella.
1. Ocelli eight on each side, of which none are rudimentary. 2
Ocelli eight on each side, of which two are rudimentary. 3
2. Claw with two inner teeth and two outer lateral teeth. T. rubra sp. nov.
Claw without any teeth, clothing of strongly-serrated setae. T. setacea sp. nov.
3. Empodial appendage absent; postantennal organ with four lobes. T. rosea Wahlgren
Empodial appendage present but rudimentary. 4
4. Claw without any inner teeth, but with a single distinctly clavate tenent hair to each foot; mucro with apical lobe and dens with apical scale-like plate. T. alba Carpenter

Triacanthella rosea Wahlgren, 1906.

This species was first recorded in New Zealand by Womersley, from Kumara, under stones. It has not been recorded again since. The insect is pinkish in colour when alive, but fades quickly in spirit. It can be distinguished as in the preceding key.

Triacanthella alba Carpenter, 1909. Plate 39, fig. 13.

So far, this species has not been discovered on the mainland of New Zealand. It can be distinguished as in the preceding key. The insect is white in life and in spirit. Two ocelli are rudimentary; and the post-antennal organ has four lobes.

Triacanthella rubra sp. nov. Plate 39, figs. 4–7.

Colour: In life specimens vary from a bright pink to a bright brick-red. In spirit the colour quickly fades to a pale pink or pinkish-white.

Clothing: Of simple setae moderate to long and not very dense.

Body: Length 1·3 mm. Antennae shorter than the head. Retractile organ at tip of Ant. IV. Ocelli eight to each side, all large

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and equal, themselves black pigmented, but with no pigment around them. Post-antennal organ four-lobed and situated well forward of the ocelli. Three large, curved, well-developed anal spines on stout papillae; papillae equal in length to spines themselves, and the three arranged with two together above the third. Cuticle very coarsely granulated.

Legs: Claw with two extremely fine inner teeth close together at about one-quarter and one-third, and a pair of lateral outer teeth at about the centre of the outer edge. Empodial appendage rudimentary. No tenent hairs.

Furcula: Short. Manubrium and mucrodens approximately equal in length. The mucro plump with strongly recurved apical tooth or hook and a large pre-apical tooth. In addition, arising from apex of dens, a very large, more or less circular, scale-like plate. Dens with at least four prominent ventral setae. Dens two and a-half times as long as mucro.

Localities: Lake Brunner, in old logs. Lake Mapourika, under kahikatea bark. Weheka, in leaf debris in the bush. Mount Messenger, among leaf mould and stones in bush. Whangarei Falls, among stones. Island Bay, Wellington, amongst rocks on the coast. Breaker Bay, Wellington. (Collected by Dr. W. R. B. Oliver.)

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Type: Slide 3/259 and Figured Paratype: slide 3/260, Dominion Museum Collection.

Triacanthella setacea sp. nov. Plate 39, figs. 1–3.

Colour: In life, yellowish-orange. Mounted, pale yellowish-brown.

Clothing: Of numerous, long, strongly-serrated setae, serrated only on one side. These are particularly prominent along dorsal surface and around tip of abdomen where some of them are as long as depth of insect's body.

Body: Length 0·5 mm. Antennae shorter than the head; four-segmented. Ant. I: II: III: IV as 10: 10: 10: 16. Retractile sense organ at apex of Ant. IV. Ocelli eight to each side, all large and equal on clear fields but each ocellus black-pigmented. Post-antennal organ smaller than an ocellus with four peripheral lobes, and situated close to anterior margin of ocellar field. Cuticle finely-tuberculate. At tip of abdomen, dorsally, two very large strongly-curved anal spines mounted on prominent papillae. Below these on terminal face of Abd. VI a smaller, straight, very sharply-pointed anal spine mounted on a papilla about half as long as spine; spine without papilla half as long as mucro. Similarly, dorsal spine three times as long as mucro.

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Legs: Claw with no teeth. Empodial appendage absent, a single non-clavate tenent hair to each foot. Furcula almost reaching to ventral tube. Dens 2 1/5 times length of mucro and with one very long ventral seta and several smaller ones. Mucro and scale-like lobe as in preceding species.

Locality: Haast Pass, west side, under moss on a tree trunk, in the forest.

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Type: Slide 3/273, Dominion Museum Collection.