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Montana Field Guide

Montana Field Guides

A Springtail - Oncopodura cruciata

Species of Concern
Native Species

Global Rank: G1G2
State Rank: S1S2

Agency Status


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General Description
[From Christiansen and Bellinger 1998:1136-1137] "Fourth antennal segment with rounded apex and dorsal row of 5 blunt setae, the basalmost smaller than others. Third segment with 2 striate sense rods, 1 smooth, swollen, blunt seta, and 1 cylindrical blunt seta apically. Second segment with 1 striate sense rod and 5 thin-walled, pointed sensillae apically. P.A.O. [postantennal organ] with 4 peripheral lobes. Tibiotarsal setae ciliate except for apical ring and distal ventral setae. Ungis with small basal lateral tooth, without inner tooth. Unguiculus lanceolate, subequal in length to inner unguis. Second tibiotarsus with dorsal spatulate seta. Basal dental subsegment with 3 inner spines, the distalmost dentate; distal segment with 1 outer and 2 inner dentate spines. Mucro subequal in length to dens, with 4 distal teeth and 2 small, basal triangular teeth. Maximum length 1.2 mm."

Not described. Presumably active throughout the year.

Diagnostic Characteristics
A combination of traits distinguish this species from other cave forms in the genus. The ciliate tibiotarsal setae and form of P.A.O. (postantennal organ) are diagnostic; number of inner serrate dental spines 3, P.A.O. with 4 lobes; only member of genus known from Montana caves (Christiansen and Bellinger 1996, 1998).

Species Range
Montana Range


Range Comments
Endemic to Lewis and Clark Caverns (= Morrison Cave), Jefferson County, Montana. Locality incorrectly given as Gallatin County (Nicholas 1960; Christiansen and Bellinger 1998); also listed only as Montana (Christiansen 1960; Christiansen and Bellinger 1996; Peck 1998). Distribution within Lewis and Clark Caverns not described.

Observations in Montana Natural Heritage Program Database
Number of Observations: 2

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Relative Density



(Observations spanning multiple months or years are excluded from time charts)

Non-migratory. Movements within Lewis and Clark Caverns not described.

Limestone cave obligate (Christiansen 1960; Nicholas 1960; Christiansen and Bellinger 1996; Peck 1998). Habitats used within Lewis and Clark Caverns not described.

Food Habits
Not described.

Reproductive Characteristics
Not described.

  • Additional ReferencesLegend:   View Online Publication
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    • Christiansen, K. 1960. A preliminary survey of the knowledge of North American cave Collembola. American Midland Naturalist 64:39-44.
    • Christiansen, K. And P. Bellinger. 1996. Cave Pseudosinella and Oncopodura New to Science. Journal of Caves and Karst Studies. 58(1):38-53.
    • Christiansen, K. and P. Bellinger. 1998. The Collembola of North America north of the Rio Grande: a taxonomic analysis. Grinnell, IA: Grinnell College. 1518 p.
    • Nicholas, G. 1960. Checklist of macroscopic troglobitic organisms of the United States. American Midland Naturalist. 64:123-160.
    • Peck, S.B. 1998. A summary of diversity and distribution of the obligate cave-inhabiting faunas of the United States and Canada. Journal of Cave and Karst Studies 60:18-26.
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Citation for data on this website:
A Springtail — Oncopodura cruciata.  Montana Field Guide.  .  Retrieved on , from