The scent gland chemistry of neogoveid cyphophthalmids (Opiliones): an unusual methyljuglone from Metasiro savannahensis

Abstract

While the chemistries of scent gland secretions from a few selected species of three families of Cyphophthalmi, namely Sironidae, Pettalidae, and Stylocellidae, have already been reported and found to consist of complex blends of naphthoquinones and methyl ketones, nothing is known about the other families. We here report on the secretions of Metasiro savannahensis Clouse and Wheeler (Zootaxa 3814:177–201, 2014), a first representative of the family Neogoveidae. The secretions from males, females and one juvenile were extracted and analyzed by gas chromatography–mass spectrometry. Twenty-five compounds were identified, all of which belong to the chemical classes of naphthoquinones and methyl ketones, confirming a hypothesized chemical uniformity of cyphophthalmid exudates. One major naphthoquinone compound, however, was new for cyphophthalmids and for arthropod exocrine secretions in general: a methyljuglone isomer, 6-methyljuglone (= 6-MJ; iupac name: 5-hydroxy-6-methyl-1,4-naphthoquinone), amounted for about 20% of the secretion and was eventually identified by synthesis. Hydroxy-naphthoquinones and their derivatives are known to possess a variety of antibiotic effects, probably enhancing the antimicrobial/antifungal potential of the Metasiro-secretion. Currently, without further data on neogoveids, the compound represents a chemical autapomorphy of M. savannahensis, and—just as the strange chloro-naphthoquinones of Sironidae and Pettalidae—adds to the repertoire of unusual naphthoquinone compounds across the Cyphophthalmi.Electronic supplementary materialThe online version of this article (10.1007/s00049-019-00288-y) contains supplementary material, which is available to authorized users.

Polymorphic scent gland secretions in Nelima harvestmen: “Sclerosomatid compounds” but different chemical lineages

“…Such a link between these two groups of compounds, if eventually proved, would represent a crucial step toward our understanding of a continuous and coherent network of harvestmen chemophylogeny. We know that methyl-ketones constitute a large class of harvestmen secretion products, and these are widely distributed across the secretions of all suborders of Opiliones (e.g., Raspotnig et al, 2005bRaspotnig et al, , 2012Raspotnig et al, , 2019Wouters et al, 2013;Shear et al, 2014;Schaider et al, 2018). Whether and how methyl-ketones might biochemically be linked to other classes of compounds of harvestmen, e.g., to (sclerosomatid) ethyl-ketones, is intriguing and a hot topic of ongoing investigation.…”