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Montana Field Guide

Montana Field Guides

A Millipede - Corypus cochlearis

Species of Concern
Native Species

Global Rank: G1G3
State Rank: S1S3

Agency Status


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General Description
Genus Corypus: Medium-sized, 30 segments, pigmented, dorsum of male flatter than female. Dorsal setae heavy, almost straight, of moderate length; lateral keels strongly projecting, inflated above, lacking margining rim. Antennae relatively short and stout. Eyes brodly triangular with up to 22 ocelli in 4 or 5 rows; front of head narrow (Loomis and Schmitt 1971). Posterior colpocoxites of male gonopds more complex than simply consisting of long, thin structure partially sheathed at base by sternal process, posterior colpocoxites of male gonopods lacking articulated basal flagellum, anterior gonopods flattened (more or less plate-like), usually larger than posterior gonopod colpocoxites, with lateral sternal processes at least partially fused to lateral regions of anterior gonopods, posterior gonopods with telopodites, anterior gonopods not fused and with sternum entire, anterior gonopods smaller than posterior gonopod colpocoxites (Shear 1976).

[From Loomis and Schmitt 1971] Corypus cochlearis: Mostly gray. Males 12 mm length, 1.8 mm width; females to 16 mm length, 2.2 mm width. Male flatter than female. Head with clypeal-labral area narrow, sides slowly diverging upward. Antennae unusually short and stout; mentum of gnathochlarium undivided, triangular, distinctly broader than long. Lateral keels on main body segments strongly projecting, swollen above, not rimed. Dorsal setae long, straight, rather heavy; outer seta on each side on a swelling at posterior angle of keel, second seta on similar swelling dorsocephalid, inner seta considerably removed from second and preceeded by elongate swelling. Anterior gonopods simple, narrow to an oblique and outwardly directed tip. Each posterior gonopod with coxal joint high, obliquely hollowed cephalomesally; secon joint stringly lobed in front; outer joint typically enlarged and curved, deeply concave and with distinct margins, a chitinized brown spot at apex. First 2 pairs of male legs slightly smaler than next 5 pair, joints 3 and 4 of legs 3 and 4 dorsoventrally thickened front to back (especially joint 4 with a distally projected turbercule below near apex); coxae of seventh legs much enlarged, joint 3 of leg 7 raised into a thick ridge along ventral side; outer 3 joints of legs 3-7 slender and similar to succeeding legs; coxae of 10 leg with large inflated sack.

Adults reported late April to early August, young reported in early August (Loomis and Schmitt 1971).

Diagnostic Characteristics
Differs from Austrotyla in proportions of gonopods; the posterior gonopod colpocoxites larger than the anterior gonopods. Differs from Taiyutyla by having modified femora 3 and 4, the posterior gonopod colpocoxites cupped anteriorly and receiving the posterior branch of the anterior gonopods (Shear 1976).

Range Comments
Endemic to Montana. Documented in Missoula and Saunders counties (Loomis and Schmitt 1971), to about 975 m elevation.

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

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



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

Riparian areas, conifer forest (western redcedar with devil's club), rockslides (Loomis and Schmitt 1971).

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Citation for data on this website:
A Millipede — Corypus cochlearis.  Montana Field Guide.  .  Retrieved on , from