Sabacon Simon 1879

Introduction

Sabacon presently comprises the largest genus within the Dyspnoi, in terms of validly described species (compare Trogulus and Paranemastoma). Animals are peculiar for their inflated palps densely set with specialized bottlebrush hairs, and a tarsus with dorsal and ventral movement. Male genital morphology is highly characteristic. The penis base is bent from the axis of the truncus and split into a bifurcate fork with the penial muscle situated between the branches and not enclosed within the truncus. A muscular tendon runs from the muscle towards the glans, which is movable against the truncus in several species. These genital morphological peculiarities have been seen as genus level characteristics (Shear 1986) but should be reevaluated in view of a systematic that is traditionally based on genital morphology within the Dyspnoi.

As a generic lineage, Sabacon is unusual within the dispersal limited Dyspnoi for showing a wide and disjunct distribution within the Holarctic, otherwise found only at the family level. Centers of endemism are known from western Europe, eastern and western North America, and several hot spots in Asia (Nepal, China, Japan, Russia), where the wealth of diversity probably still remains to be discovered.

Taxonomy and Discussion of Phylogenetic Relationships

Close relationship to Taracus and Hesperonemastoma has been proposed but is weakly supported and phylogenetic analyses show Sabacon in an isolated position within the Ischyropsalidoidea (Giribet et al. 2010). The morphological diversity within Sabacon is high concerning palpal and cheliceral apophyses and genital morphology. Several different functional penis types exist; a system comparable with the Nemastomatinae and a thorough reinvestigation concerning this divergence may reveal a similar system that needs to be accounted for. Tomicomerus bryantii, now included in Sabacon, seems to show a different genital morphological setting (Shear 1975), while material for a comprehensive reinvestigation is necessary. Many Sabacon species are known from a few individuals only, and Sabacon diversity is probably largely underexplored as animals are rare and difficult to collect.

Ecology and Life History

Sabacon requires high and constant humidity along with cool temperatures. Species are restricted to dense forests of different composition, caves or high alpine habitats mostly in combination with and close to running water. Dispersal abilities seem low, although many species are fairly long-legged. Many species have a distinct phenology and mature late in autumn, which renders adult specimens scarcely available for studies.

References

Abbott, R. H. R. 1981. A new opilionid to Great Britain. Newsletter of the British arachnological Society 30:4-4a.

Cokendolpher, J. C. 1984. A new species of Sabacon Simon from Oregon (Arachnida: Opiliones: Sabaconidae). Canadian Journal of Zoology 62:989-991.

Dresco, E. 1970. Recherches sur la variabilité et la phylogénie chez les Opiliones du genre Ischyropsalis C. L. Koch (Fam. Ischyropsalidae), avec la création de la famille nouvelle des Sabaconidae. Bulletin du Muséum National d’Histoire Naturelle, 2e Serie 41:1200-1213.

Dunlop, J.A. 2006. Baltic amber harvestman types (Arachnida: Opiliones: Eupnoi and Dyspnoi). Fossil Record 9:167-182.

Giribet, G., Vogt, L. Pérez-González, A., Sharma, P. and A. B. Kury. 2010. A multilocus approach to harvestman (Arachnida: Opiliones) phylogeny with emphasis on biogeography and the systematics of Laniatores. Cladistics 26:408-437.

Lopez, A., Emerit, M. and M. Rambla. 1980. Contribution à l'etude de Sabacon paradoxum Simon 1879 (Opiliones, Palpatores, Ischyropsalidae). Stations nouvelles, particularités électro-microscopiques du prosoma et de ses appendices. Comptes Rendus de la Vième Colloque d’Arachnologie d’Expression Française, 1979, Barcelona 9:147-158.

Martens, J. 1972. Opiliones aus dem Nepal-Himalaya. I. Das Genus Sabacon Simon (Arachnida: Ischyropsalididae). Senckenbergiana biologica 53:307-323.

Martens, J. 1983. Europäische Arten der Gattung Sabacon Simon 1879 (Arachnida: Opiliones: Sabaconidae). Senckenbergiana biologica 63:265-296.

Martens, J. 1989. Sibirische Arten der Gattung Sabacon Simon (Arachnida: Opiliones: Sabaconidae). Senckenbergiana biologica 69:369-377.

Menge, A. 1854. Footnotes. In: Koch, C. L. and G.C. Berendt (eds.) Die im Bernstein befindlichen Crustaceen, Myriapoden, Arachniden und Apteren der Vorwelt. Edwin Groening, Berlin.

Roewer, C. F. 1939. Opilioniden im Bernstein. Palaeobiologica 7:1-5.

Shear, W. A. 1975. The opilionid genera Sabacon and Tomicomerus in America (Opiliones, Troguloidea, Ischyropsalidae). The Journal of Arachnology 3:5-29.

Shear, W. A. 1986. A cladistic analysis of the opilionid superfamily Ischyropsalidoidea, with description of the new family Ceratolasmatidae, the new genus Acuclavella and four new species. American Museum Novitates 2844:1-29.

Suzuki, S. 1974. The Japanese species of the genus Sabacon (Arachnida, Opiliones, Ischyropsalididae). Journal of Science of the Hiroshima University, Series B, Division 1 (Zoology) 25:83-108.

Thaler, K. 1976. Two remarkable relict arachnids from northern Italy: Sabacon simoni Dresco (Opiliones, Ischyropsalididae), Louisfagea rupicola (Simon) (Araneae, Tetragnathidae). Bulletin of the British arachnological Society 3:205-210.

Tsurusaki, N. and D. Song. 1993. Two new species of Sabacon from Sichuan Province, China (Arachnida: Opiliones: Sabaconidae) Zoological Science 10:155-159.