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Montana Field Guide

Montana Field Guides

A Millipede - Orophe cabinetus

Species of Concern

Global Rank: G1G3
State Rank: S1S3

Agency Status
USFWS:
USFS:
BLM:


 

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General Description
Genus Orophe: Large millipeds to about 30.0 mm length. Composed of head and 20 postcephalic (body) segments in both sexes, appearing parallel-sided but tapering caudad. Head of normal appearance, smooth, polished. Antennae moderately long and slender. Legs 3 of males modified, the coxae with an anteriorly directed process. Gonopodal telopodite twisted and constricted into cingulum at juncture of acropodite and prefemur, long and slender, divided distad, well beyond midlength, into short, subequal distal elements, a short, plate-like, broadly triangular solenomerite, overhung by a short terminal portion of the acropodite, latter not redivided (Hoffman 1964; Shelley 1993).

[From Hoffman 1964; Shelley 1993] Orophe cabinetus: Males to at least 21.3 mm length and 4.1 mm width, females to at least 28.7 mm and 4.5 mm width. Antennae reaching back just beyond caudal margin of 2nd tergite, with 4 terminal cones and ovoid microsensilla on distal margin of 6th antennomere (segment), relative lengths of antennomeres as follows (longer to shorter): 3, 6, 2, 4, 5, 1, 7; 1 subglobose, 2-6 clavate, 7 short and truncate. Collum with ends terminating slightly above those of following tergite, caudal margin relatively straight. Paranota strongly depressed, angling strongly ventrad and imparting convex appearance to segments; anterior corners rounded; caudolateral corners rounded on 2nd tergite, blunt on 3-14 and becoming progressively narrower on remaining segments. Sides of metazonites smooth with slight ridges above coxae on body segments 2-4. Sternum of segment 5 with minute lobes subtending 4th coxae; that of segment 6 moderately depressed. Postgonopodal sterna glabrous with slight transverse linear impressions originating between leg pairs. Coxae of legs 3 with short subconical and hirsute lobes directed forward, remaining coxae without modifications; ventrodistal margins of prefemora with very faint rounded lobes. Gonopod coxa moderately large, with 2 setae on anterior surface above origin of cannula. The coxal setae vary from 2 macrosetae to a field of 6-8 regular setae of varying lengths; thus 2 macrosetae are not diagnostic of this species. Prefemoral process absent. Acropodite narrow at base and twisted at juncture with prefemur, thereby imparting torsion and a cingulum at this point, leaning dorsad and curving mediad, narrowing proximad and expanding progressively distad beginning near midlength, terminal portion clavate, broadly rounded apically, overhanging and slightly longer than subtriangular solenomerite, the latter expanding into subtriangular basal lobe on medial side, directed toward distal extremity of acropodite and coaxial with stem.

Phenology
Little information. Adults reported early May to early September (Loomis and Schmitt 1971; Shelley 1993).

Diagnostic Characteristics
Differs from closely related species (and only other member of genus) in adjacent Idaho (Orophe unicus) by the solenomerite coaxial with stem of telopodite (instead of being perpendicular to stem of telopodite), and directed toward distal extremity of the telopodite (instead of being directed away from distal extremity of the telopodite).

Range Comments
Montana endemic. Reported from Lake, Mineral, and Sanders counties (Loomis and Schmitt 1971; Shelley 1993), at 610 m to 1220 m elevation.

Summary of Observations Submitted for Montana
Number of Observations: 10

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Relative Density

Recency

 

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



Habitat
Coniferous forest: including western red cedar, Douglas-fir, western larch, devil's club; under moss and humus, on damp earth (Loomis and Schmitt 1971; Shelley 1993).

References
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Citation for data on this website:
A Millipede — Orophe cabinetus.  Montana Field Guide.  .  Retrieved on , from