Trilasma Goodnight & Goodnight, 1942
Trilasma is characterized by the presence of anvil shaped tubercles on the median hood process and the lack of cheliceral glands and associated bristle fields on the basal cheliceral segments in males. In addition, the border of large cells formed by elongated tubercles on the dorsal scute is redrawn by smaller cells attached to the large-cell pattern (Shear 2010). Male genital morphology is uniform and similar to Ortholasma, yet the intersection of stylus and glans is more gradual in most Trilasma species while pronounced and bulb-like in Ortholasma (Shear and Gruber 1893, Shear 2010).
Taxonomy and Discussion of Phylogenetic Relationships
Trilasma is closely related to Ortholasma and has just recently been elevated from sub-genus based on morphological characters, the more southern distribution and additional species pronouncing a well delineated generic lineage (Shear 2010). The male genitalia of the two genera are very similar and they have two lateral processes on the prosoma, separating them from other Ortholasmatinae. T. sbordonii seems to have an isolated position within the Trilasma, showing additional spines on the glans penis and an extremely large and inflated hood, while other modifications may be related to cave adaption (Šilhavý 1973, Shear and Gruber 1893). No further systematic concepts within the genus seem present.
Ecology and Life History
With T. tropicum most likely collected in Honduras, Trilasma includes probably the most southern distributed species within the Dyspnoi,. All other species are from Mexico, yet records are scarce and further discoveries are to be expected (Shear 2010). Most records are from high altitudes between 2100-3050 m. Known habitats are different types of high altitude forest often associated with conifers. Regardless of altitude many specimens have been collected in caves, while only T. sbordonii shows cave adaption (Shear 2010).
References
Shear, W. A. 2010. New species and records of ortholasmatine harvestmen from México, Honduras, and the western United States (Opiliones, Nemastomatidae, Ortholasmatinae). ZooKeys 52:9-45.
Shear, W. A. and J. Gruber. 1983. The opilionid subfamily Ortholasmatinae (Opiliones, Troguloidea, Nemastomatidae). American Museum Novitates 2757:1-65.
Šilhavý, V. 1973. Cavernicolous opilionids from Mexico (Arachnida, Opiliones). Subterranean Fauna of Mexico. Part II. Quaderno della Accademia Nazionale dei Lincei, Problemi Attuali di Scienza e di Cultura 171(2):175-194.
Credits
Page created by Axel L. Schönhofer. Angela DiDomenico helped improve the English.
Taxonomy and Discussion of Phylogenetic Relationships
Trilasma is closely related to Ortholasma and has just recently been elevated from sub-genus based on morphological characters, the more southern distribution and additional species pronouncing a well delineated generic lineage (Shear 2010). The male genitalia of the two genera are very similar and they have two lateral processes on the prosoma, separating them from other Ortholasmatinae. T. sbordonii seems to have an isolated position within the Trilasma, showing additional spines on the glans penis and an extremely large and inflated hood, while other modifications may be related to cave adaption (Šilhavý 1973, Shear and Gruber 1893). No further systematic concepts within the genus seem present.
Ecology and Life History
With T. tropicum most likely collected in Honduras, Trilasma includes probably the most southern distributed species within the Dyspnoi,. All other species are from Mexico, yet records are scarce and further discoveries are to be expected (Shear 2010). Most records are from high altitudes between 2100-3050 m. Known habitats are different types of high altitude forest often associated with conifers. Regardless of altitude many specimens have been collected in caves, while only T. sbordonii shows cave adaption (Shear 2010).
References
Shear, W. A. 2010. New species and records of ortholasmatine harvestmen from México, Honduras, and the western United States (Opiliones, Nemastomatidae, Ortholasmatinae). ZooKeys 52:9-45.
Shear, W. A. and J. Gruber. 1983. The opilionid subfamily Ortholasmatinae (Opiliones, Troguloidea, Nemastomatidae). American Museum Novitates 2757:1-65.
Šilhavý, V. 1973. Cavernicolous opilionids from Mexico (Arachnida, Opiliones). Subterranean Fauna of Mexico. Part II. Quaderno della Accademia Nazionale dei Lincei, Problemi Attuali di Scienza e di Cultura 171(2):175-194.
Credits
Page created by Axel L. Schönhofer. Angela DiDomenico helped improve the English.
