Siro

Distinguished from other cyphophthalmid genera by the combination of: eyeless condition, elongated body form, presence of two tarsal claws on all legs, and position of ozophores. Differs from Nemastoma and related genera by body proportions and details of tarsal structure. Differs from Parasiro by the absence of eyes and geographic distribution. Identification to species level requires examination of male genitalia, particularly the shape of the glans and the structure of the truncus.

Small, elongated arachnids with a narrow body form. Eyeless, with no ocular structures present. Body coloration typically pale to yellowish-brown. Chelicerae are relatively long and slender. The prosoma and opisthosoma are broadly joined without a narrow pedicel. Tarsi of walking legs possess two claws. The ozophores (scent glands) are positioned laterally on the opisthosoma. Integument finely granular.

Moist microhabitats in forested and karstic environments. Found in leaf litter, under stones, in soil crevices, and in caves. Requires high humidity and stable moisture conditions. Often associated with limestone substrates and subterranean environments. Some species show troglomorphic adaptations including elongated appendages and pale coloration in cave-dwelling populations.

Mediterranean region, including southern Europe (Spain, France, Italy, Balkans), North Africa, and parts of the Middle East. Center of diversity in the western Mediterranean, particularly the Iberian Peninsula and Italy. Disjunct populations occur in suitable karstic and forested habitats throughout the range.

Activity patterns poorly documented. Likely active year-round in suitable microhabitats due to buffered environmental conditions. Surface activity, when observed, appears more common during moist periods in spring and autumn. Cave-dwelling species show no apparent seasonal pattern.

Predator and scavenger in soil and litter food webs. Consumes small invertebrates, fungal material, and decaying organic matter. Serves as prey for larger soil-dwelling invertebrates including spiders, centipedes, and predatory beetles. Contributes to nutrient cycling through consumption and processing of detrital material.

No direct economic importance. Occasionally encountered by cavers and soil biologists. Serves as indicator species for habitat quality in forest and karst ecosystems. Some cave-dwelling species of conservation concern due to restricted ranges and habitat vulnerability.

• NemastomaSimilar elongated body form and habitat preferences, but Nemastoma possesses eyes and has a different tarsal formula and body proportions.
• ParasiroConvergent body shape in some species, but Parasiro retains eyes and has a different distribution (primarily Caucasus region).
• IberogastracarusOverlapping distribution in Iberian Peninsula, but differs in body shape and tarsal structure.

• harvestmen
• Opiliones
• Cyphophthalmi
• eyeless
• cave-dwelling
• soil fauna
• Mediterranean
• karst
• Sironidae

• BugGuide
• NCBI Taxonomy
• Catalogue of Life
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