Ortholasma colossus, Shear, William A., 2010

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 : 18-20

Ortholasma colossus sp. n. Figs 18102030, 31

Types.

Male holotype and two female paratypes collected in Bear Den Cave, Sequoia National Park, Tulare Co., California, 1 May 2004, by J. Krejcaet al. deposited in California Academy of Sciences (CAS); male and female paratypes from same locality, collected 17-18 July 2003 by J. Krejca et al. deposited in Field Museum of Natural History (FMNH).

Diagnosis.

The notably larger size of the females distinguishes this species of Ortholasma from all others.

Etymology.

The species name, a Latin noun in apposition, refers to a gigantic statue, or by implication, anything outlandishly large for its type.

Description.

Male holotype: total length, 4.5, width, 2.25. Color uniform blackish brown, legs somewhat lighter brown. Carapace arcuate, about twice as wide as long, with complete lateral and posterior submarginal keels; median keels connect eye tubercle and innermost lateral hood process, lateral keels also arising on innermost lateral hood process. Two acute lateral hood processes each about half as long as median hood process. Circumocular keels absent, only subocular portion present. Median hood process arising dorsally on eye tubercle, length 1.6, width 1.0; bearing 24 lateral T-shaped tubercles, all connected. Metapeltidium free, complete keel along anterior margin. Scute 2.6 long, 2.25 wide. Pattern of scute keels typical, paired median scute spines low, scarcely standing above level of keels; posterior marginal keel with complete fenestrations (Fig. 2).

Chelicerae (Figs 4, 5, 10) with basal article 0.9 long, 0.25 wide, prominent epigamic gland with dense vestiture of small, fine setae (Fig. 5), otherwise sparsely setose; second article 0.75 long, 0.21 wide, with small, curved mediobasal tooth. Palpus (Figs 6, 20) with dense vestiture of clavate setae; trochanter with several ventral seta-tipped tubercles; tibia swollen; dimensions given in Table 1. Legs in order of length, 2 (11.95), 4 (9.7), 3 (6.3), 1 (5.8); metatarsus 2 with 8 false articulations, otherwise false articulations lacking; tarsi 1-4 with 10, 11, 10, 11 articles respectively. Lengths of leg segments given in Table 1. Leg femora with typical ornamentation (Fig. 7).

Genital operculum broadly rounded, marginate, suture faintly indicated. Penis (Fig. 30) 1.0 long, typically thin; glans (Fig. 31) sinuate with hooked tip, subtended by small setae.

Female paratype: total length, 6.6, width, 4.2. Nonsexual characters as in male (Fig. 3); median hood process 1.7 long, 0.9 wide. Scute 4.5 long, 4.2 wide. Chelicera without gland on basal article, distal article lacking tooth, basal article 1.05 long, 0.26 wide; distal article 0.90 long, 0.24 wide. Palpal tibia not swollen, dimensions given in Table 2. Legs in order of length, 2 (10.6), 4 (7.34), 3 (5.7), 1 (4.87); metatarsus 2 with 6 false articulations; tarsi 1-4 with 7, 8, 9, 11 articles respectively. Lengths of leg segments given in Table 2. Genital operculum broadly rounded, marginate, without suture. Ovipositor typical.

Distribution.

All specimens deposited in CAS unless otherwise noted. CALIFORNIA: Fresno Co., 3 mi. south of Trimmer, 4 June 1967, under rhyolite in oak forest, T. Briggs, female (AMNH). Tulare Co., Johnsondale, Kern River, 4 July 1956, V. Roth, W. Gertsch, female (AMNH); Lost Soldier’s Cave, December 1977, A. Grubbs, female (AMNH); 21 July 2003, J. Krejcaet al., female, 23 July 2003, molt fragment, 9 November 2003, female; Lightening Cave, 30 June 1952, A. Lange, female (used for SEM; AMNH); Sequoia National Park, Ash Mtn., 26 April 1951, E. Schlinger, male (AMNH); Paradise Cave, 30 April 2004, J. Krejca et al., male, juveniles; Lange Cave, 6 May 2004, J. Krejca et al., male, 2 females, 6 May 2004, male, female, 7 May 2004, late instar juvenile; Carmoe Crevice, 5 July 2003, J. Krejcaet al., male; May’s Cave, 16 May 2004, J. Krejca et al., female, early juvenile; Hidden Cave, 15 November 2003, J. Krejca, V. Loftin, male; Highway 245, 14 mi. north of Woodlake, near Cottonwood Creek and Rattlesnake Creek confluence, 26 March 2009, M. Hedin et al., female (pictured alive and in the field in Fig. 1).

Notes.

The preponderance of cave records is probably misleading; the species shows no signs of troglomorphosis and specimens from caves are nearly identical to the few surface-collected specimens. The cool, moist environment of caves probably attracts individuals (troglophily). Caves have been much more thoroughly collected than surface habitats, and in this case most of the records come from a biological survey of the caves of Sequoia and Kings Canyon National Parks. The caves mentioned in the Distribution section are located on a map in Shear and Shelley (2008: Fig. 9). The Fresno Co. record may be questionable. The label places Trimmer in Kern Co., but according to all sources, it is an unincorporated community in Fresno Co., on the north shore of the Pine Flat Reservoir (shown on some maps as Isabella Reservoir). The elevation in the vicinity is less than 610 m (2000') asl, while no other records of the species but one (near Woodlake) come from below 2100 m (about 7000') asl. If accurate, this record suggests a wider distribution for Ortholasma colossus sp. n.

The size of the species, at least 50% longer than the next largest, is striking when seen side-by-side with congeners; only Ortholasma rugosum approaches it with some 4.5-mm-long males. However, most males of Ortholasma colossus sp. n. are longer than 4.5 mm, and the largest females of Ortholasma rugosum are only 4.8 mm long, compared to the usual 6-7 mm in colossus sp. n.