Ceratolasmatidae Shear 1986

Introduction

The Ceratolasmatidae appear currently ill-defined (discussed below). Here, a narrow family concept is considered, including Acuclavella and Ceratolasma only, as these two genera are most likely closely related and share many morphological features. Similarities comprise the horned process on the eye mound, lack of bottle-brush hairs, a relatively simple penis and a characteristic composition of sternal elements (Shear 1986, Martens 1969). The two genera are restricted to the northwestern United States of America, where they inhabit permanently humid to wet habitats, often in combination with running water. The distribution of the genera does not overlap; neither seems to have specific microhabitat preferences (Shear 1986).

Taxonomy and Discussion of Phylogenetic Relationships

Ceratolasmatidae as defined and described by Shear (1986) has been altered considerably and now comprises the closely related genera Acuclavella and Ceratolasma. Still included is Crosbycus, whose position has been repeatedly questioned within the superfamily (e.g. Gruber 2007 and overview within, Giribet et al. 2010). It had been considered close to Hesperonemastoma by Shear (1986) but was not considered when Hesperonemastoma was transferred to Sabaconidae (Giribet et al. 2010). Good family definitions of Sabaconidae and Ceratolasmatidae are now lacking and will have to await a more comprehensive revision of the Ischyropsalidoidea. Ceratolasmatidae, reduced to Acuclavella and Ceratolasma, represents a well-supported morphological sister to Ischyropsalis (Martens 1969, Gruber2007).

References

Giribet, G., L. Vogt, A. Pérez González, P. Sharma 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.

Gruber, J. 2007. Dyspnoi - Historical systematic synopsis. In: Pinto-da-Rocha, R., Machado, G., & Giribet, G. (eds.), Harvestmen: the biology of Opiliones. Harvard University Press, Cambridge: 131-135.

Martens, J. 1969. Die Abgrenzung von Biospezies auf biologisch-ethologischer und morphologischer Grundlage am Beispiel der Gattung Ischyropsalis C. L. Koch 1839 (Opiliones, Ischyropsalididae). Zoologische Jahrbücher Systematik 96 (2): 133-264.

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