Olgania excavata Hickman, 1979

Rix, Michael & Harvey, Mark, 2010, The spider family Micropholcommatidae (Arachnida: Araneae: Araneoidea): a relimitation and revision at the generic level, ZooKeys 36 (36), pp. 1-321 : 91-92

Olgania excavata Hickman, 1979

Figs 7O , 152D–E, 176–177, 178A, 188–192, 213, 223A–B

Olgania excavata Hickman, 1979: 73 , figs 34–38. Brignoli, 1983: 372. Davies, 1985: 55. Platnick, 2009.

Type material. Holotype male: Gordon River Valley , Tasmania, Australia, from moss, 42°35'30"S, 145°44'00"E, 29.I.1976, C. Howard et al. ( AMS KS2709 ).

Paratypes: Allotype female, Gordon River Valley , 1.5 km W. of junction of Gordon and Denison Rivers, Tasmania, Australia, from moss, 42°43'12"S, 145°49'00"E, 16.II.1978, L. Hill et al. ( AMS KS2710 ); 1 female, same data as allotype except 42°43'S, 145°50'E, 8.II.1977, C. Howard et al. ( AMS KS97160 ) .

Other material examined. AUSTRALIA: Tasmania: Gordon River region , 3.II.1978, L. Hill et al., 1♀ ( AMS KS72967 ) ; Bubs Hill, just W. of Victoria Pass, in cave (1935 Cave , BH-4), 28.IV.1987, R. Raven, T. Churchill, N. Platnick, 1♁, 6♀ ( AMNH) ; Bubs Hill, 1935 Cave (BH-4), 29.XII.1986, S. Eberhard, 3♁, 1♀ ( AMNH) ; Bubs Hill, Thylacine Lair (BH-203), 30.IV.2006, M. Rix, A. Clarke, L. Boutin, 1♁, 4♀ ( WAM T76938 SEM ♀) ; same data, 1♀ ( WAM T80021 DNA-MPE) ; same data, 1♀ ( QVM 13 : 44520) ; same data except 1.XI.1988 (written on label as 1.xi.1989), S. Eberhard, 1♁, 1♀ ( AMS KS29588 ) ; same data except 1.XI.1988, 2♀ ( QVM 13 : 12727) ; Cardia Cave (Acheron 1/2 Cave) (AR-X2), Acheron River , western World Heritage Area , 24.III.1989, S. Eberhard, 3♁, 6♀ ( AMS KS21307 ) ; Kutikina Cave (Fraser Cave) (F-34), Franklin River, western World Heritage Area , 23.III.1989, S. Eberhard, 3♁, 4♀ (AMS KS21297 SEM♁ ♀) ; same data except 21.iii.1989, 1♁, 2♀ ( AMS KS29477 ) ; same data, 1♁, 1♀ ( QVM 13 : 12778) .

Remarks. Olgania excavata is known only from western and south-western Tasmania, where it has been collected from Kutikina Cave (Franklin River karst), Cardia Cave (Acheron River karst) and caves in the Bubs Hill karst (including 1935 Cave and Thylacine Lair) (Figs 213, 219). Several specimens have also been collected from moss in temperate rainforest in the Gordon River Valley, and these are the only known epigean populations of Olgania .

At Bubs Hill (Fig. 219) the spiders build small, horizontal sheet-webs ( Fig. 223B ) on the walls or floor of limestone caves, usually in cracks or depressions, or under rocks or small ledges near seepages. The webs are held in position by vertical support-lines, and are often extended to effectively fill a particular crevice. The web is composed of an extremely fine mesh of silk, and some webs have two parallel layers of silk. The spiders hang upside-down in the centre of the webs, and walk very slowly towards the periphery if disturbed. Both adult males and females can be found sitting in their own webs, and the spiders seem to be at least loosely colonial, with several webs usually found in close proximity (first recorded by Eberhard et al. 1991). Egg sacs are hung above the sheet-webs singly or in pairs, and each circular egg sac contains only a single egg, which is surrounded by a thin, loosely-woven layer of fine elastic silk ( Fig. 223A ).

Figures

Figure 7. The genera of Micropholcommatidae, illustrated with habitus photographs of representative male specimens. A–D tribe Micropholcommatini: A Micropholcomma caeligenum Crosby & Bishop B Pua novaezealandiae Forster C Austropholcomma florentine sp. n. D Tricellina gertschi (Forster & Platnick). E–M tribe Textricellini: E Eterosonycha aquilina sp. n. F Epigastrina fulva (Hickman) G Raveniella peckorum sp. n. H Rayforstia vulgaris (Forster) I Normplatnicka lamingtonensis (Forster)] Eperiella alsophila sp. n. K Algidiella aucklandica (Forster) L Taliniella nigra (Forster) M Tinytrella pusilla (Forster). N Patelliella adusta sp. n., tribe Patelliellini. O–P subfamily Taphiassinae: O Olgania excavata Hickman P Taphiassa robertsi sp. n. Q–R subfamily Gigiellinae: Q Gigiella milledgei sp. n. R Gigiella platnicki sp. n. Note that Guiniella tropica (Forster) is not illustrated.

Figure 223. Biology of Taphiassinae. A–B Olgania excavata Hickman from the Bubs Hill karst, Tasmania: A egg sac (removed from web) and single egg B sheet-web, suspended on wall of cave at Thylacine Lair, Bubs Hill karst. C–E Taphiassa globosa sp. n. from Cape Le Grand National Park, Western Australia (WAM T94488): C live female photographed in captivity ‘cleaning’ leg I D egg sac and two eggs, laid in captivity E live female with egg sac. F–G live female T. robertsi sp. n. from D’Entrecasteaux National Park, Western Australia (WAM T94528), photographed in captivity. H possible egg sac of T. magna sp. n., photographed suspended on a moist, mossy rock wall near Goathouse Cave, Mount Lidgbird, Lord Howe Island. Images by M. Rix.