A Novel Class of Defensive Compounds in Harvestmen: Hydroxy-γ-Lactones from the Phalangiid Egaenus convexus.

When threatened, the harvestman Egaenus convexus (Opiliones: Phalangiidae) ejects a secretion against offenders. The secretion originates from large prosomal scent glands and is mainly composed of two isomers of 4-hydroxy-5-octyl-4,5-dihydro-3H-furan-2-one (1), a ß-hydroxy-γ-lactone. The compounds were characterized by GC-MS of their microreaction derivatives, HRMS, and NMR. After the synthesis of all four possible stereoisomers of 1, followed by their separation by chiral-phase GC, the absolute configurations of the lactones in the Egaenus secretion was found to be (4S,5R)-1 (90%) and (4S,5S)-1 (10%). Hydroxy-γ-lactones represent a new class of exocrine defense compounds in harvestmen.

Methyl-ketones in the scent glands of Opiliones: a chemical trait of cyphophthalmi retrieved in the dyspnoan Nemastoma triste.

The homologous and phylogenetically old scent glands of harvestmen-also called defensive or repugnatorial glands-represent an ideal system for a model reconstruction of the evolutionary history of exocrine secretion chemistry ("phylogenetic chemosystematics"). While the secretions of Laniatores (mainly phenols, benzoquinones), Cyphophthalmi (naphthoquinones, chloro-naphthoquinones, methyl-ketones) and some Eupnoi (naphthoquinones, ethyl-ketones) are fairly well studied, one open question refers to the still largely enigmatic scent gland chemistry of representatives of the suborder Dyspnoi and the relation of dyspnoan chemistry to the remaining suborders. We here report on the secretion of a nemastomatid Dyspnoi, Nemastoma triste, which is composed of straight-chain methyl-ketones (heptan-2-one, nonan-2-one, 6-tridecen-2-one, 8-tridecen-2-one), methyl-branched methyl-ketones (5-methyl-heptan-2-one, 6-methyl-nonan-2-one), naphthoquinones (1,4-naphthoquinone, 6-methyl-1,4-naphthoquinone) and chloro-naphthoquinones (4-chloro-1,2-naphthoquinone, 4-chloro-6-methyl-1,2-naphthoquinone). Chemically, the secretions of N. triste are remarkably reminiscent of those found in Cyphophthalmi. While naphthoquinones are widely distributed across the scent gland secretions of harvestmen (all suborders except Laniatores), methyl-ketones and chloro-naphthoquinones arise as linking elements between cyphophthalmid and dyspnoan scent gland chemistry.

A Model for Phylogenetic Chemosystematics: Evolutionary History of Quinones in the Scent Gland Secretions of Harvestmen.

By the possession of unique exocrine scent glands, Opiliones (harvestmen) arise as a perfect model for studies on the evolutionary history of secretion chemistry. Among gland compounds of harvestmen, it is the quinones that represent recurring elements across the secretions of all suborders. Reliable data on quinone-distribution, however, is only known for Laniatores (benzoquinones) and Cyphophthalmi (naphthoquinones). We here unraveled the quinone-distribution across scent gland secretions of the third large harvestman suborder, the Palpatores (= Eu- and Dyspnoi): Naphthoquinones were found in phalangiid Eupnoi across all subfamilies as well as in nemastomatid (and at least one ischyropsalid) Dyspnoi. Benzoquinones (1,4-benzoquinone) were restricted to a small entity within Eupnoi, namely platybunine Phalangiidae, probably misplaced Gyantinae (currently Sclerosomatidae) and Amilenus (incertae sedis). Our findings, combined with data from Laniatores and Cyphophthalmi, allow evaluation of a comprehensive chemosystematic model for Opiliones for the first time. Evolutionary scenarios imply naphthoquinones as scent gland compounds of common ancestry, having evolved in an early harvestman ancestor and present in cyphophthalmids and palpatoreans, but lost in laniatoreans. Benzoquinones evolved later and independently at least twice: once in the secretions of gonyleptoid Laniatores (alkylated benzoquinones), and a second time in a lineage of phalangiid Eupnoi (1,4-benzoquinone).

Benzoquinones from scent glands of phalangiid harvestmen (Arachnida, Opiliones, Eupnoi): a lesson from Rilaena triangularis.

In case of disturbance, the phalangiine harvestman Rilaena triangularis (Eupnoi, Phalangiidae) emits a directed jet from large prosomal scent ("defensive") glands. The pungent-smelling secretion was analyzed by gas chromatography-mass spectrometry and found to contain mainly 1,4-benzoquinone along with 1,4-naphthoquinone and caprylic (=octanoic) acid. While various alkylated benzoquinones are characteristic for the scent gland secretions of many grassatorean Laniatores, this is the first incidence of benzoquinone-based chemical defense in palpatorean harvestmen.

On the enigmatic scent glands of dyspnoan harvestmen (Arachnida, Opiliones): first evidence for the production of volatile secretions.

While considerable knowledge on the chemistry of the scent gland secretions from the opilionid suborders Laniatores and Cyphophthalmi has been compiled, it is the Palpatores (Eupnoi and Dyspnoi) where chemical data are scarce. In particular, the Dyspnoi have remained nearly unstudied, mainly due to their reported general reluctance to release secretions as well as to the phenomenon of production of insoluble-and inaccessible-solid secretion. We here show that at least certain nemastomatid Dyspnoi, namely all three species of genus Carinostoma, indeed produce a volatile secretion, comprising octan-3-one, 6-methyl-5-hepten-2-one and acetophenone in species-specific combinations. In all Carinostoma spp., these volatiles are embedded in a semi-volatile, naphthoquinone matrix (mainly 1,4-naphthoquinone and 6-methyl-1,4-naphthoquinone). In detail, acetophenone and traces of naphthoquinones characterize the secretions of Carinostoma carinatum. A mixture of octan-3-one, 6-methyl-5-hepten-2-one and large amounts of naphthoquinones were found in C. elegans, and 6-methyl-5-hepten-2-one together with small amounts of naphthoquinones in the secretions of C. ornatum. So far, exclusively naphthoquinones had been reported from a single dyspnoan hitherto studied, Paranemastoma quadripunctatum.

[Psychoeducation leads to a reduction in fear of spiders in 8- to 9-year-old children - a pilot study]. / Reduktion der auf Spinnen bezogenen Ängste durch Psychoedukation bei 8- bis 9-jährigen Kindern - eine Pilotstudie.

OBJECTIVE: In Western societies spiders are among the least liked of all arthropods, eliciting feelings of fear and disgust. The clinical manifestation of this fear - spider phobia - is a common anxiety disorder. In most cases the disorder has an early onset in childhood. The symptoms show a chronic course and can persist into adulthood if not treated. Etiological models emphasize the role of modeling and negative information transmission for the acquisition of the disorder. Even though powerful psychotherapeutic methods exist, referral to treatment is rather uncommon for children. Often spontaneous remission is expected, but that is atypical. METHOD: The current study developed a psychoeducative program on spiders for elementary school children and evaluated it on a sample of 36 children aged 8 to 10 years. The main goal of this pilot study was to test the feasibility of the program. RESULTS: The study showed a reduction of fear of spiders after psychoeducation in girls and boys with previously high or moderate fear of spiders. CONCLUSIONS: The program could become a valuable contribution to the prevention of spider phobia and should be evaluated in future controlled trials.

Nitrogen-containing compounds in the scent gland secretions of European cladonychiid harvestmen (Opiliones, Laniatores, Travunioidea).

The exocrine secretions from prominently developed prosomal scent glands in four species of the European laniatorean harvestman genus Holoscotolemon (Laniatores, Travunioidea, Cladonychiidae) were analyzed by gas chromatography - mass spectrometry. Two major alkaloidal compounds were detected: Nicotine accounted for more than 97% of the secretion in Holoscotolemon jaqueti and H. oreophilum, whereas the chemically related nicotinoid alkaloid anabaseine was the major compound in H. lessiniense. In addition, a series of minor nitrogen-containing components was found, namely 3-(1-methyl-2-piperidinyl)-pyridine and anabasine, in H. jaqueti and H. oreophilum, and anabasine together with 2,3'-bipyridyl in H. lessiniense. By contrast, extracts of adult H. unicolor did not show any components. In one juvenile specimen of H. unicolor, however, low amounts of alkyl pyrazines (dimethyl-isobutyl- and dimethyl-isopentylpyrazines) were detected. Nitrogen-containing components previously were found in Sclerobunus robustus (an American travunioid harvestman), so scent gland-derived alkaloids may be widespread or even common in the Travunioidea. Alkaloids have not been reported for other opilionid scent gland secretions outside the Travunioidea, and we hypothesize that they may be the phylogenetically ancestral allomones in the Laniatores, having been reduced and replaced by a phenol- and benzoquinone-rich chemistry in the more derived grassatorean taxa.

Functional anatomy of scent glands in Paranemastoma quadripunctatum (Opiliones, Dyspnoi, Nemastomatidae).

The morphological organization and functional anatomy of prosomal defensive (scent) glands in Paranemastoma quadripunctatum, a representative of the dyspnoid harvestmen, was investigated by means of histological semithin sections, software-based 3D-reconstruction and scanning electron microscopy. Scent glands comprise large, hollow sacs on either side of the prosoma, each of these opening to the outside via one orifice (ozopore) immediately above coxa I. In contrast to the situation known from laniatorean, cyphophthalmid and some eupnoid Opiliones, ozopores are not exposed but hidden in a depression (atrium), formed by a dorsal integumental fold of the carapace and the dorsal parts of coxae I. Glandular sacs are connected to ozopores via a short duct which is equipped with a specific closing mechanism in its distal part: A layer of modified epidermal cells forms a kind of pad-like tissue, surrounding the duct like a valve. Several muscles attached to the anterior parts of the glandular reservoir and to the epithelial pad may be associated with ozopore-opening. The actual mechanism of secretion discharge seems to be highly unusual and may be hypothesized on the basis of corroborating data from behavioral observations, scent gland anatomy and secretion chemistry as follows: Enteric fluid is considered to be directed towards the ozopores via cuticular grooves in the surface of the coxapophyses of legs I. Then, the fluid is sucked into the anterior part of the scent gland reservoirs by the action of dorsal dilator muscles that widen the reservoir and produce a short-term negative pressure. After dilution/solution of the naphthoquinone-rich scent gland contents, a secretion-loaded fluid is thought to be discharged with the help of transversal compressor muscles. This is the first detailed study on the functional anatomy of scent glands and the mechanisms of secretion discharge in the Dyspnoi.

Naphthoquinones and anthraquinones from scent glands of a dyspnoid Harvestman, Paranemastoma quadripunctatum.

Extracts of Paranemastoma quadripunctatum (Opiliones, Dyspnoi, Nemastomatidae) contained seven components, all of which likely originated from the secretion of well-developed prosomal scent glands. The two main components (together accounting for more than 90% of the secretion) were identified as 1,4-naphthoquinone and 6-methyl-1,4-naphthoquinone. The minor components were 1,4-naphthalenediol, two methoxy-naphthoquinones (2-methoxy-1,4-naphthoquinone, and 2-methoxy-6-methyl-1,4-naphthoquinone) and two anthraquinones (2-methyl-9,10-anthraquinone and a dimethyl-9,10-anthraquinone). While some chemical data on scent gland secretions of the other suborders of Opiliones (Cyphophthalmi, palpatorean Eupnoi, and Laniatores) already exist, this is the first report on the scent gland chemistry in the Dyspnoi. Naphthoquinones are known scent gland exudates of Cyphophthalmi and certain Eupnoi, methoxy-naphthoquinones and anthraquinones are new for opilionid scent gland secretions.