Trilasma ranchonuevo, 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 : 24-26

Trilasma ranchonuevo sp. n. Figs 112132, 3347

Type.

Male holotype (TMM) from Rancho Nuevo, Tamaulipas, México, collected 10 April 1982 by Terri Treacy.

Diagnosis.

Like Trilasma trispinosum sp. n., ranchonuevo sp. n. has three lateral hood processes, but the median hood process of ranchonuevo sp. n. is much broader and has more dorsal tubercles. There are more small keel cells on the scute of trispinosum sp. n. than in ranchonuevo sp. n.The male of ranchonuevo sp. n. has a single false articulation in each of the second and fourth leg femora; such are present in all legs of trispinosum sp. n. males. Tarsal counts of the single available specimen are 3, 4, 4, 4, the lowest for any Trilasma .

Etymology.

The species epithet, a noun in apposition, refers to the type locality.

Description.

Male holotype: total length, 2.7, width, 1.6. Color pale tan to yellowish brown. Carapace arcuate, about 1.5X as wide as long, with complete lateral and posterior submarginal keels; pair of median keels connecting eye tubercle and innermost lateral hood process, lateral keels arising both on innermost and middle lateral hood processes. Three blunt lateral hood processes each about one-half as long as median hood process. Circumocular keels suppressed, subocular portion vaguely indicated, eyes relatively large, bulging. Median hood process arising dorsally on eye tubercle, with nearly parallel sides, then converging distally, length 0.9, width 0.3; median keels of carapace continuing as rows of lateral tubercles on median hood process, about 18-20 lateral tubercles, linearly connected; 5 or 6 dorsal tubercles present, connected linearly to one another but not obviously to lateral tubercles. Metapeltidium free, complete keel along anterior margin, 6 tubercles posterior to keel, connected to it by single branch each. Scute 1.6 long, 1.6 wide. All keels relatively low. Small keel cells present only on areas 2-4, as single transverse rows of 6-8 cells. Paired median scute spines prominent, on areas 4, 5 larger than adjacent keel tubercles (Fig. 47).

Chelicerae (Fig. 11) with basal article 0.62 long, 0.22 wide, sparsely setose, with small, median distal tooth; second article 0.62 long, 0.20 wide, with dark, median basal tooth. Palpus (Fig. 21) with dense vestiture of clavate setae; patella and tibia swollen, but glands not marked by patches of small setae, trochanter with ventral seta-tipped tubercles very low, almost obselete; dimensions given in Table 3. Legs in order of length, 2 (6.66), 4 (4.74), 3 (3.12), 1 (3.0); metatarsus 2 with 2 false articulations, femora 2, 4 with single basal false articulation; tarsi 1-4 with 3, 4, 4, 4 articles respectively. Lengths of leg segments given in Table 3. Length/width ratios of femora, in order: 3.64, 8.33, 3.46, 7.0. Leg femora with typical ornamentation.

Genital operculum broadly rounded, marginate, notched. Penis (Figs 32, 33) typical of genus.

Notes.

The male holotype of Trilasma ranchonuevo sp. n. is significantly larger than the male paratype of Trilasma trispinosum sp. n. and has longer legs. The pattern of small cells on the scute is quite different, and the median hood process is much broader in relation to its width, with many more dorsal tubercles. On the left side of the body of the holotype, the innermost lateral hood process is irregularly developed, suggesting that the innermost process is the “extra” one and that its presence or absence might be subject to variation.

Rancho Nuevo is in the Sierra Nevada Oriental in western Tamaulipas, near the Nuevo Léon border and about 22 miles northwest of Ciudad Victoria. Coordinates: 23°51'50.40N; 99°27'07.43W, elevation 8600' (2650 m).While the region around Rancho Nuevo is famous for its caves, this specimen was collected on the surface and shows no signs of troglobiosis.