FWF-Projekt P21819-B16 „Scent glands of Palpatores (Opiliones)“

PI: Günther Raspotnig; project associate: Miriam Schaider



A pair of large, prosomal, sac-like defensive glands is a characteristic feature of all harvestmen (Opiliones): for these arachnids, being non-poisonous and not able to spin, scent glands may be considered the most important means for chemical defense against  predators, fungi and bacteria for the last 300 million years. Opilionid scent glands diversified with respect to morphology, function and chemistry, paralleling the radiation of harvestmen into their extant species diversity (6500 species!) and in dependence to ecological conditions: by now, many scent gland “eco-types” and, most interestingly, highly taxon-specific secretions have evolved.


In this project, the scent glands of the so-called Palpatores were investigated: the Palpatores comprise more than 2000 species, including the typical daddy-longlegs but also short-legged, aberrantly-looking harvestmen with many adaptations to a cryptic life in soil. Traditionally, the Palpatores are divided into Eupnoi and Dyspnoi: both groups, in particular the Dyspnoi, so far represented “white spots” in opilionid scent gland research. It is, however, these groups which show the greatest scent gland-heterogeneity, thus representing the key to a consistent, evolutionary explainable overall-picture of scent glands in the Opiliones.


In this project, 1) we generated model data for completely unknown dyspnoan scent gland chemistry for the first time. Moreover, at least, 3 scent gland types in Dyspnoi could be classified: a) a solid type which is frequently characterized by hidden ozopores (= glandular orifices), covered by an external “atrium” and by solid secretion boli in the scent gland reservoirs; b) a volatile type which produces mainly short-chain ketones in a naphthoquinone matrix; and c) a semi-volatile type which contains naphthoquinones only. 2) The Eupnoi show variations of the volatile type but produce different, taxon-specific chemicals: a) a large group of Phalangiidae releases unusual lactones and related compounds (new for opilionid chemistry!); b) a group of Sclerosomatidae produces different phenolics whereas c) other sclerosomatids rely on a mix of various acyclic ketones. d) While in most phalangiids, the compounds mentioned above are accompanied by naphthoquinones, the latter are replaced by benzoquinones in the phalangiid subfamily Platybuninae. In total, more than 100 different components, including a number of new natural compounds, could be extracted from palpatorean secretions.


Thus, this newly generated chemical data base on palpatorean secretions eventually allows drawing a widely consistent chemosystematic picture of scent gland chemistry in the Opiliones, and thus offers the opportunity for a model reconstruction of character evolution in an exocrine system across a whole animal order.


Project related publications (only peer-reviewed papers mentioned; chronologically)


  • (10) Raspotnig, G., Schaider, M., Föttinger, P., Leutgeb, V., and Komposch, Ch. (2015): Benzoquinones from scent glands of phalangiid harvestmen (Arachnida, Opiliones, Eupnoi): a lesson from Rilaena triangularis. Chemoecology 25: 63-72.
  • (9) Raspotnig, G., Bodner, M., Schäffer, S., Koblmüller, S., Schönhofer, A., and Karaman, I. (2015): Chemosystematics in the Opiliones (Arachnida): a comment on the evolutionary history of alkylphenols and benzoquinones in the scent gland secretions of Laniatores. Cladistics 31: 202-209.
  • (8) Raspotnig G, Schaider M, Stabentheiner E, Leis HJ, Karaman I (2014) On the enigmatic scent glands of dyspnoan harvestmen (Arachnida, Opiliones): First evidence for the production of volatile secretions. Chemoecology 24(2), DOI 10.1007/s00049-014-0146-5;
  • (6) Raspotnig G, Schwab J, Karaman I (2012) High conservatism in the composition of scent gland secretions in the Cyphophthalmi: evidence from Pettalidae (Arachnida, Opiliones). J Chem Ecol 38:437–440. DOI 10.1007/s10886-012-0108-8 (URL: http://link.springer.com/article/10.1007/s10886-012-0108-8)
  • (5) Schaider M, Komposch C, Stabentheiner E, Raspotnig G (2011) Functional anatomy of scent glands in Paranemastoma quadripunctatum (Opiliones, Dyspnoi, Nemastomatidae). J Morph 272: 1182–1191; DOI: 10.1002/jmor.10973; (URL: http://onlinelibrary.wiley.com/doi/10.1002/jmor.10973/pdf)
  • (4) Raspotnig G, Schaider M, Föttinger P, Komposch C, Karaman I (2011) Nitrogen-containing compounds in the scent gland secretions of European cladonychiid harvestmen (Opiliones, Laniatores, Travunioidea). J Chem Ecol 37:912–921. DOI 10.1007/s10886-011-9996-2 (URL: http://link.springer.com/article/10.1007/s10886-011-9996-2)
  • (3) Schaider M, Komposch C, Stabentheiner E, Raspotnig G (2010) Preliminary studies on the morphology of scent glands of soil-dwelling harvestmen (Arachnida, Opiliones). Acta Soc Zool Bohemicae 74:97–101 (URL: http://www.zoospol.cz/?sekce=act&jazyk=en)
  • (1) Raspotnig G, Leutgeb V, Schaider M, Komposch C (2010) Naphthoquinones and anthraquinones from scent glands of a dyspnoid harvestman, Paranemastoma quadripunctatum. J Chem Ecol 36:158–162. DOI 10.1007/s10886-010-9745y (URL: link.springer.com/article/10.1007/s10886-010-9745-y)

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