User:Telquessewen/Ortholasma

Ortholasma

Telquessewen/Ortholasma
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Arachnida
Order:	Opiliones
Suborder:	Dyspnoi
Superfamily:	Nemastomatoidea
Family:	Ortholasmatinae
Genus:	Ortholasma
Species
see text
Synonyms
Ortholasma

Overview

Ortholasma is part of a group of spiders known as harvestmen (Opiliones). Most commonly people call these spiders "Daddy Long Legs". This genus contains a group of species with elaborate dorsal cuticular structures including a cephalic hood.

Description

Adults

One of the most distinguishing features of this genus is the hood that covers the pedipalps and chelicerae. The dorsal surface is covered in a cuticular pattern of rectangular and hexagonal cells. Unlike Dendrolasma, the metapeltidium is free from the scute and carapace. The body color is generally dark brown, and often they are covered in soil. The legs are longer as is characteristic of Opiliones, with the chelicerae and pedipalps being approximately half of the length of the body. The male's penis is long and scelerotized at the glans with a hook. Female's have a nemastomatid ovipositor, that is a folded cuticle with sparse setation. Ortholasma and Dendrolasma are closely related. Ortholasma can be distinguished by a rounder carapace and a highly arched hood. It has monomorphic glans spination, compared to Dendrolasma which has polymorphic glans spination. The palpi have clavate hairs and the glans penis has uniform setation with a hook, whereas Dendrolasma's has helical torsion.[1]

Juveniles

Note: The following information applies for presubadults and subadults in the family Ortholasmatinae.

Subadults resemble adults but have softer body walls that give them a rounder form. Their carapace is not an elaborate cuticular structure like their adult counterparts, and is instead replaced by conical tubercles. Juvenile's do not have a cephalic hood, and the pigment of the carapace is lighter. The palpi of nymphs are longer compared to body length up until the adult molt where they take their characteristic shape. Clavate hairs dominate the palpi until the adult molt where they become ordinary setae . The legs of nymphs and subadults are shorter than adults and have fewer tarsal joints .

Species & Distribution

Distribution

This genus ranges from British Colombia all the way down towards Mexico. Each subspecies occupies its own range.

• Ortholasma rugosum - California
• Ortholasma pictipes - Northern California to British Colombia
• Ortholasma levipes - Coastal California and foothills and Western Slopes of the Sierra Nevada
• Ortholasma setulipes - Southern California
• Ortholasma bolivaria - Southern Mexican HighlandsTransverse Volcanic Biotic Province
• Ortholasma sbordonni - Sierra Madre Oreintal region, Mexico
• Ortholasma coronadense - Baja California and Coronado Islands

Species

Differences Between the Species

• Ortholasma rugosum – Differs from the others by having unbanded femora with a rough tuberculate appearance that lack pseudoarticulations .
• Ortholasma pictipes – This species differs by having banded legs and a light stripe down the middle of its carapace .

• Ortholasma levipes – This species has uniform brown coloration. The legs have broad, blunt denticles and pseudoarticulations [1]. • Ortholasma setulipes – Has pseudoarticulations in the second leg femora. Additionally, this species has does not clumped denticles in its legs giving them a smooth appearance [1]. • Ortholasma bolivaria – Contains a highly arched hood with dorsal projections unlike its Californian counterparts [1]. • Ortholasma sbordonni – Has troglobitic adaptations that set it apart from O. bolivaria [1]. • Ortholasma coronadense -This species has only been found once and was described by Cockerell. According to Cockerell the hood is nearly circular [4].

References

Shear, W.A. and J. Gruber. 183. American Museum Novitates. The Opilionid Subfamily Ortholasmatinae (Opiliones, Troguloidea, Meastomatidae).The American Museum of Natural History Central Park West at 79th Street, New York, N.Y.

External links

• [1] - San Diego State University. Marshal Hedin Lab, Arachnid Systematics, Evolution, and Conservation.