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Fig. 1. Petoriba harti adult female (non-type) - dorsal habitus.

Fig. 2. Petoriba harti adult female (non-type) - detail of ambulacrum - lateral "claws" reduced to small pad with tenent hairs and central empodium.

Fig. 3. Petoriba harti adult male (non-type) - dorsal habitus.

Fig. 4. Petoriba harti adult male (non-type) - detail of aedeagus.

Material examined

non-types

Taxonomy

Subfamily Bryobiinae

Tribe Petrobiini

Distribution

+Australia, Brazil, CIS, China, Costa Rica, Egypt, El Salvador, France, Greece, Hainan Island, Hawaii, India, Iran, Israel, Italy, Japan, Koreq, Madagascar, Madeira Island, Malawi, Mauritiana, Mauritius, Mexico, Mozambique, New Caledonia, Okinawa Island, Portugal, South Africa, Spain, Taiwan, *USA, Vanuatu

Taxonomy Changes

Neophyllobius harti Ewing 1901

Tetranychina harit (Ewing) Banks 1917

Petrobia harti (Ewing) Pritchard & Baker 1955

Petrobia (Tetranychina) harti (Ewing) Tuttle & Baker 1968

Tetranychina macdonoughi McGregor 1917, synonymy Pritchard & Baker 1955

Tetranychina tuberculata Kishida 1921, synonymy Pritchard & Baker 1955

Tenuicrus errabundus Womersley 1940, synonymy Pritchard & Baker 1955

Neobryobia spectabilis Reck 1941

Tetranychina spectabilis (Reck) Reck 1948

Petrobia spectabilis (Reck) Reck 1959, synonymy Pritchard & Baker 1955

Tetranychina agerati Sayed 1946, synonymy Pritchard & Baker 1955

Diagnosis

Female

• dorsal setae set on tubercles (Fig. 1)
• dorsal setae are much longer than distance to next seta
• peritreme ends in short hook like golfclub, and does not protrude 
• dorsal setae f1 shorter than other setae inserted medially on dorsum
• leg I is twice length of body (Fig. 1)
• empodium (claw-like) as long as tenent hairs on lateral claws (pad-like) (Fig. 2)

Male

• legs I & IV are three times the length of the body (Fig. 3)
• aedeagus almost straight, tapering evenly along length to sharp point distally (Fig. 4)

Hosts

*type host unknown

> 40 recorded species of host plant, including: Ageratum conyzoides (Asteraceae), Artemisia herba-alba (Asteraceae), Artocarpus heterophyllus (Moraceae), Atropa belladonna (Solanaceae), Averrhoa carambola (Oxalidaceae), Citrus grandis (Rutaceae), Crotalaria anagyroides (Fabaceae), Fragaria sp. (Rosaceae), Ipomoea batatas (Convolvulaceae), Malus domestica (Rosaceae), Medicago sativa (Fabaceae), Mentha pulegium (Lamiaceae), Oxalis articulata, O. corniculata, O. corymbosa, O. europaea, O. latifolia, O. pes-caprae (Oxalidaceae), Pennesetum longistylum (Poaceae), Petunis hybrida (Solanaceae), Plantago lanceolata (Plantaginaceae), Saccharum officinarum, S. spontaneum (Poaceae), Solanum melongena (Solanaceae), Trifolium sp. (Fabaceae), Vitis vinifera (Vitaceae)

Biology

Petrobia harti is dark brown with light red legs.

This species occurs throughout the world on Oxalis spp. (Oxalidaceae).  Dubitzki and Gerson (1987) found that Petrobia harti developed more rapidly and lived longer on Oxalis corniculata a known host, than on O. articulata which is not known as a natural host for the mite species.  This species of spider mite is in greatest numbers in the field in early summer and the popluation drops right down during winter.  Males are rare in this species, making up only 10% or less of field populations.  The mites spend most of their time, and lay their eggs, on the ventral surface of the host leaves.  Diapause in the field was not observed.

References

Banks, N. (1917)  New mites, mostly economic (Arach. Acar.).  Entomol. News 28: 193-199

Dubitzki, E. and Gerson, U. (1987)  The natural history of Petrobia (Tetanychina) harti (Ewing) and Petrobia (Mesotetranychus) tunisiae Manson (Acari: Tetranychidae) in the laboratory.  Experimental and Applied Acarology 3: 91-94

*Ewing, H.E. (1909)  New species of Acarina.  Trans. Am. Entomol. Soc. 35: 401-415 

Kishida, K. (1921)  Zool. Mag. 33: 449 

McGregor, E.A. (1917)  Descriptions of seven new species of red spiders.  Proc. U.S. Natl. Mus. 51: 581-590

Pritchard, A.E. and Baker, E.W. (1955)  A revision of the spider mite family Tetranychidae.  Pacific Coast Entomology Society Memoirs 2: 1-472

Reck, G.F. (1941)  New genus and species of spider mites in Georgia (Tetranychidae, Acari).  Soob. Akad. Nauk Gruz. S.S.R. 2: 749-753

Reck, G.F. (1948)  Fauna of spider mites (Tetranychidae, Acari) from Georgia.  Tr. Zool. Inst. Akad. Nauk S.S.R. 8: 175-185

Reck, G.F. (1959)  A key to tetranychoid mites.  Fauna Trans. Caucasia Akad. Nauk Gruz. S.S.R. 1: 1-152 

Sayed, M.T. (1946)  Contribution to the knowledge of Acarina of Egypt. V. Five new species of Tetranychidae.  Bull. Soc. Fouad., Ier Entomol. 30: 79-97 

Tuttle, D.M. and Baker, E.W. (1968)  Spider mites of South-western United States and a revision of the family Tetranychidae.  Tucson, Ariz., Univ. Ariz. Press: 1-143

+Womersley, H. (1940)  Studies in Australian Acarina, Tetranychidae and Trichadenidae.  Transactions of the Royal Society of South Australia 64: 233-265

Notes

Womersley (1940) recorded this species in Australia under the name Tenuicrus errabundus.

There may be more than one species in Australia being referred to as P. harti.  What we are calling P. harti may not be the true species.