Ortholasma Banks, 1894

Shear, William A., 2010, New species and records of ortholasmatine harvestmen from Mexico, Honduras, and the western United States (Opiliones, Nemastomatidae, Ortholasmatinae), ZooKeys 52, pp. 9-46 : 17

Ortholasma Banks, 1894

Ortholasma Banks 1894, p. 11; Shear and Gruber 1983, p. 14 (in part; with all pre-1983 references); Shear and Gruber 1987, p. 134.

Type species.

Ortholasma rugosum Banks 1894, by monotypy.

Emended diagnosis.

Ortholasmatines in which the median hood process arises rostrally and is distinctly spoon-shaped, widest past its midlength, and lacks a median, dorsal row of T-shaped tubercles ( Trilasma species have parallel-sided median hood processes with a median row of tubercles); two lateral hood processes; males with glands dorsally on the first cheliceromere (glands lacking in Trilasma ); male first cheliceromere with or without distal inner tooth; males of some species with palpal femoral and patellar glands (needs verification for all species using scanning electron microscopy); keel cells large, not subdivided into smaller cells (some cells subdivided in Trilasma ; sometimes in Dendrolasma ).

Notes.

Ortholasma species are best distinguished from one another by characters of the dorsal ornamentation, in particular the numbers of lateral T-shaped tubercles on the median hood process and the elevation of the median paired spines of the scute. The proportions of the appendages and their microsculpture are also valuable, but the form of the penis is so similar in all species that it is of little systematic value. The absence of an inner tooth on the basal articles of the chelicerae of males may be synapomorphic for at least some Ortholasma ; however, Ortholasma rugosa has a small tooth, and the tooth is not present in all species of Trilasma .

As delimited here, Ortholasma is found almost exclusively in the United States and Canada, though Ortholasma coronadense extends into Baja California, México, on Islas Coronados, offshore and just south of the border with the United States. This species has not been reported from mainland Baja California, but likely occurs there.

Key to species of Ortholasma (adapted from Shear and Gruber 1983)