Trilasma trispinosum, 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 : 26-28

Trilasma trispinosum sp. n. Figs 912, 132234, 3542, 43

Types.

Female holotype, male and female paratypes (TMM) from Puerto del Aire, Veracruz, México, collected 6 January 1966 by J. Richter, in cloud forest oak litter.

Diagnosis.

Differing from all other Trilasma except ranchonuevo sp. n.in the three, rather than two, lateral hood processes of the carapace, but distinct from ranchonuevo sp. n. in the extremely narrow median hood process, with only a few dorsal tubercles.

Etymology.

The species epithet refers to the three lateral hood processes.

Description.

Female holotype: total length, 2.6, width, 1.7. Color uniform chestnut brown, legs somewhat lighter brown, proximal parts of femora whitish yellow. Carapace arcuate, about 1.5X as wide as long, with complete lateral and posterior submarginal keels; pair of median keels connect eye tubercle and innermost lateral hood process, lateral keels also arising on innermost lateral hood process. Three blunt lateral hood processes each about one-fourth as long as median hood process. Circumocular keels absent, subocular portion vaguely indicated, eyes relatively large, bulging. Median hood process arising dorsally on eye tubercle, narrow, length 0.9, width 0.11; median keels of carapace continue as rows of reduced lateral tubercles on median hood process, about 18-20 lateral tubercles, linearly connected; only 2 or 3 dorsal tubercles present. Metapeltidium free, complete keel along anterior margin, 6 tubercles posterior to keel, connected to it by single branch each. Scute 1.5 long, 1.7 wide. All keels relatively low. Small keel cells of scute area 1 absent, small keel cell rows progressively wider posteriorly, widest on area 4; small cells of area 5 in two groups either side of midline. Paired median scute spines small, on areas 4, 5 no larger than adjacent keel tubercles (Figs 42, 43).

Chelicerae (Fig. 12) with basal article 0.65 long, 0.18 wide, sparsely setose; second article 0.52 long, 0.18 wide. Palpus with dense vestiture of clavate setae; trochanter with ventral seta-tipped tubercles; dimensions given in Table 4. Legs in order of length, 2 (5.45), 4 (4.99), 3 (3.10), 1 (3.05); metatarsi without false articulations, femur 4 with single basal false articulation; tarsi 1-4 with 4, 5, 4, 5 articles respectively. Lengths of leg segments given in Table 4. Length/width ratios of femora, in order: 3.5, 7.0, 3.75, 5.25. Leg femora with typical ornamentation.

Genital operculum broadly rounded, marginate, with suture. Ovipositor typical of subfamily.

Male paratype: total length, 2.3, width, 1.2. Nonsexual characters as in female, but dorsal ornament reduced, obscured in paratype by secretion; median hood process 0.79 long, 0.2 wide. Scute 1.2 long, 1.2 wide. Chelicera (Fig. 13) without gland on basal article, second article with forward-projecting tooth, basal article 0.60 long, 0.20 wide; distal article 0.51 long, 0.15 wide. Palpal patella and tibia swollen, small ventral glandular areas indicated by patches of fine setae (Fig. 22), dimensions of palpus given in Table 5. Legs in order of length, 2 (5.76), 4 (4.96), 3 (3.32), 1 (3.22); all femora with single, basal false articulation, metatarsi without false articulations; tarsi 1-4 with 4, 5, 4, 5 articles respectively. Lengths of leg segments given in Table 5. Length/width ratios of femora, in order: 3.9, 9.8, 4.0, 6.1. Genital operculum broadly rounded, marginate, with two small, lateral notches. Penis typical (Figs 34, 35).

Notes.

This species is the most distinctive of all Trilasma species due to the very short and narrow median hood process, which has only one or two dorsal armed tubercles. The female holotype (Figs 42, 43) is anomalous in that the keel extending from the eye tubercle to the posterior margin of the carapace is doubled on the left side. The pattern of keel cells is very distinct in the female holotype and paratype, but the male paratype has a much-reduced ornament. However, this is uncertain because of the thick secretion covering the dorsum and median hood process in the single available specimen; this material could not be cleaned off using ultrasonics, or methanol as a solvent. Notable also is the presence in the male of basal false articulations in all the femora. In the female, only the fourth femur has a basal false articulation. The presence of palpal glands in the male palpal patellae and tibiae is indicated by the patch of fine setae on the ventral side, and in still-adhering secretion on the tibia.

Puerto del Aire is a small village west of the larger city of Acultzingo, Veracruz, and southeast of Morelos Canadá, Puebla, virtually at the Puebla-Veracruz border (18°42'13.5N; 97°21'29.6W). The elevation is about 2556 m (7500 ft.) asl.