Platysetosus occultus, Dylewska, Bloszyk & Halliday, 2006

Dylewska, M., Błoszyk, J. & Halliday, R. B., 2006, Platysetosus occultus gen. nov., sp. nov., a new genus and species of mite from Tasmania (Acari: Uropodina), Zootaxa 1223, pp. 55-64 : 57-63

Platysetosus occultus sp. nov.

Material examined

Holotype: female, Australia, Tasmania, Pirates Road, Tasman Peninsula, 2.5 km SW of Eaglehawk Neck, south track, 43°03’S 147°55’E, 21 March 1989, Nothofagus cunninghamii , moss on fallen log, coll. J. Diggle, (TAS­045) (in ANIC). Paratypes: 46 females; 2 females, Savage River, Pipeline Road, 41°30’S 145°20’E, 21 April 1989, moss on ground, coll. H. Mitchell, (TAS­007); 5 females, Pirates Road, Tasman Peninsula, 2.5 km SW of Eaglehawk Neck, south track, 43°03’S 147°55’E, 21 March 1989, Nothofagus cunninghamii , moss on fallen log, coll. J. Diggle, (TAS­045); 1 female, Pirates Road, Tasman Peninsula, 2.5 km SW of Eaglehawk Neck, south track, 43°03’S 147°55’E, 21 March 1989, Nothofagus cunninghamii , moss on ground, coll. J. Diggle, (TAS­046); 1 female, Pirates Road, Tasman Peninsula, 2.5 km SW of Eaglehawk Neck, south track, 43°03’S 147°55’E, 21 March 1989, Nothofagus cunninghamii , litter, coll. P. Greenslade and J. Diggle, (TAS­052); 2 females, Spero River, 42°38’S 145°22’E, 23 February 1989, litter, coll. J. Marsden­Smedley, (TAS­054); 1 female, Spero River, 42°38’S 145°22’E, 25 February 1989, pitfall traps, coll. J. Marsden­Smedley, (TAS­055); 1 female, Hibbs Lagoon, 42°34’S 145°19’E, 27 February 1989, litter, coll. S. Smith, (TAS­058); 14 females, Frodshams Pass, 42°49’S 146°13’E, 18 November 1988, thamnic rainforest, litter, coll. P. Greenslade, (TAS­062); 1 female, Thumbs Lookout, 42°42’S 147°50’E, 9 September 1988, parallel gullies, litter, coll. P. Greenslade, (TAS­064); 1 female, Mount Horror, site 1, 41 °04’S 147°44’E, litter, coll. M. Neyland, (TAS­072); 1 female, Bradshaws Road, below Mount Murchison, Loftus Hill Memorial Reserve, 41°50’S 145°37’E, 21 April 1989, site 1, moss on ground, coll. H. Mitchell, (TAS­098); 1 female, Mount Mangana, site 1, 43 °22’S 147°17’E, 9 April 1989, dead wood, coll. P. Greenslade, (TAS­136); 8 females, Mt. Mangana, Bruny Island, site 2, 43 °21’S 147°13’E, 4 April 1989, litter, J. Diggle and P. Greenslade coll. (TAS­203); 2 females, Mount Michael, 41º10’S 148º00’E, 20 September 1989, 740 m, leaf litter, coll. H. Mitchell, ( TASII /6); 1 female, Cradle Mountain, camping ground, site 1, 41 º35’S 145º55’E, 18 September 1989, in moss, coll. R. Coy, ( TASII /7); 1 female, Mount Victoria, 41º20’S 147º41’E, 29 September 1989, 900 m, leaf litter, coll. R. Coy, ( TASII /8); 1 female, Mount Michael, 41º10’S 148º00’E, 11 June 1989, in moss, coll. R. Coy, ( TASII /9); 1 female, Frodshams Pass, 42º49’S 146º22’E, 20 October 1989, 620 m, pitfall trap, coll. R. Coy, ( TASII /12); 1 female, Cradle Mountain, 41º35’S 145º55’E, 18 November 1989, camping ground, leaf litter, coll. R. Coy, ( TASII /15). In ANIC and AMU.

Description

Female. Well sclerotised, deep brownish colour.

Dorsal idiosoma ( Fig. 1 ). Size range of dorsal shield 500–570x 350– 400 m. Idiosoma elliptical, with indistinct broad vertex. Dorsal shield oval, surface with characteristic ornamentation of numerous irregularly shaped pits. Dorsal setae numerous, hair­like.

Marginal shield narrow, with chararacteristic festoon ornamentation; marginal setae simple, short.

Ventral idiosoma ( Figs. 2 , 3 ). Ventral shields fused and heavily sclerotised. Sternal shield smooth. Four pairs of sternal setae: st1–st3 short and simple, st4 very long; st1 located above anterior edge of epigynium; st2–st4 lateral to epigynium. Epigynium elongate, parallel­sided, with arched anterior and straight posterior margins. Surface of epigynium smooth anteriorly, with characteristic ornamentation in central and posterior areas. Stigmata situated opposite coxae III, with a short hook­like peritreme reaching edge of idiosoma ( Fig. 4 D). Pedofossae present, pedofossae IV oriented transversely, displaced towards podosoma.

Opisthosoma shortened and covered with characteristic sculpture. Ventral setae diverse in shape and length: V1 simple and short; V2 hair­like, very long; V3 simple; 9–14 pairs of very long, broad and flat setae Vs inserted posteriorly. Submarginal setae Ss simple, short. Anus with one pair of simple adanal setae; unpaired postanal seta Pa absent.

Tritosternum with broad triangular base, lacinia forked distally into four branches; base of tritosternum covered by coxae I ( Fig. 4 B).

Gnathosoma ( Fig. 4 ). Corniculi massive, horn­like. Hypostomal setae simple; h1, h3 very long, h2 and h4 short ( Fig. 4 A). Seta Pv1 on palp trochanter simple, short; Pv2 very long, serrated midway along its length ( Fig. 4 C).

Chelicera long and narrow; fixed digit of chelicerae longer than the movable digit and angular ( Fig. 4 E).

Male. Unknown.

Etymology

The name occultus (secret, mystery) refers to the fact that we are unable to place this species in any known family of Uropodina .

Notes

Platysetosus is an endemic Tasmanian genus. P. occultus has been found at nine localities distributed over most of Tasmania ( Fig. 5 ). The genus is characterised by the characteristic sculpture and chaetotaxy of the ventral opisthosoma. In other known species of Uropodina there is no record of the 9–14 pairs of very long flat setae found on the ventral opisthosoma of P. occultus . We place Platysetosus in the superfamily Uropodoidea Evans, 1972, but its family placement is unknown. It can not be placed in any of the 36 families of Uropodina listed by Hirschmann (1979). In particular it can not go into the large family Uropodidae because it has claws on leg I. This claw is like that of Nenteria , but Platysetosus has horn­like corniculae, compared with the digitate corniculae of Nenteria . The family­level classification of the Uropodina of Hirschmann (1979) is very heavily biased towards the European fauna. When the faunas of Australia and other areas with poorly­known faunas of Uropodina are more fully documented, that classification will need to be completely revised, and unusual genera such as Platysetosus will need to be taken into account.

The specimens of P. occultus that we have examined are all females (30 specimens), and the species would appear to be thelytokous. This is a very rare feature for Uropodina in the Southern Hemisphere.

We have described P. occultus on the basis of specimens with 10 pairs of large flattened opisthosomal setae. However, we are aware of the existence of specimens with 9, 10, 12, and 14 such setae on one or both sides. The number of such specimens is extremely limited, and the significance of this variation in setal numbers is not known. It may be that more than one species is present, or there could be a single variable species. The answers to these questions must await the collection of more specimens from a greater number of localities. The species appears to favour very wet microhabitats such as moss, in Nothofagus forest. Detailed searching of that habitat in different areas of Tasmania should yield the specimens required for a thorough analysis of this group.

Figures

FIGURE 1. Platysetosus occultus sp. nov., female, dorsal idiosoma.

FIGURE 2. Platysetosus occultus sp. nov., female, ventral idiosoma.

FIGURE 3. Platysetosus occultus sp. nov., female, ventral.

FIGURE 4. Platysetosus occultus sp. nov., female. A, hypostome; B, tritosternum; C, setae of palp trochanter; D, peritreme; E, chelicera.

FIGURE 5. Map of Tasmania showing collecting localities for Platysetosus occultus sp. nov.