Idagona Buckett and Gardner 1967

Shear, William A., 2007, Cave millipeds of the United States. V. The genus Idagona Buckett & Gardner (Chordeumatida, Conotylidae, Idagoninae), Zootaxa 1463, pp. 1-12 : 2-3

Idagona Buckett and Gardner 1967

Idagona Buckett and Gardner 1967 , p. 120. Shear, 1972, p. 270.

Diagnosis: Distinct from all other North American conotylid millipeds in the complete loss of the telopodite articles of the posterior gonopods and the reduction of those appendages to a small pair of coxites which pass anteriorly between the anterior gonopods ( Figs. 1 -8, 19, 20). Additionally, the third legpair femora in males are inflated and bear an adenostyle ( Figs. 9-12, 14 ); the tenth coxae in males are enlarged and lobed; the eleventh coxae are unmodified.

Notes: The species of Idagona have been recorded from five discrete areas (Map 1). The new species I. lehmanensis occurs in southeastern Nevada, far separated from the other localities; this species is highly distinctive: the fourth as well as the third prefemora are modified in males, and the gonopods differ in their much greater complexity and the proportions of the several elements. I. westcotti is known from three clusters of lava tubes in southern Idaho, and I. jasperi is from two high-altitude caves in Logan Canyon, Cache Co., Utah, not far over the border between Idaho and Utah. Accordingly, jasperi more closely resembles westcotti and can be separated from that species only by the details of gonopod shape ( Figs. 3 , 7. 19. 20). The distinct habitat and locality reinforces the hypothesis that jasperi is a reproductively isolated population, while the 1. In point of fact, it is the reduced coxites of the posterior gonopods that are extended anteriorly between the anterior gonopods, but this is an homologous arrangement necessitated by the extreme reduction of the posterior gonopods, which in Idagona consist only of the small coxites.

three clusters of westcotti localities harbor populations not distinguishable by gonopod or other differences ( Figs. 1, 2 , 5, 6, 9. 10, 15. 16).

For conservation reasons, and at the request of the collectors, the exact locations of caves mentioned in this paper are not given. Map 1 represents geometrically average locations for clusters of caves, or the approximate location of an individual cave.

The types of the new species described below are deposited in the collections of the Field Museum of Natural History (FMNH), Chicago.

MAP 1. Central Rocky Mountain and Great Basin region of the United States, showing distribution of Idagona species. Shaded areas are karst or pseudokarst (lava beds). Triangles, I. westcotti ; square, I. jasperi ; circle, I. lehmanensis . Triangle 1, general location of Blowhole-Sand Lake, Ice Capades, and London Tunnel Caves; triangle 2, general location of Government Cave; triangle 3, general location of Giant Arch and Pot O’ Gold Caves (may be two names for the same cave). Map by S. J. Taylor.

Figures

FIGURES 1 – 4. Gonopods of Idagona species. 1, Idagona westcotti, Giant Arch Cave, posteriorventral view. 2. I. westcotti, Ice Capades Cave, posterioventral view. 3. I. jasperi, n. sp. posterioventral view. 4. I. lehmanenesis, n. sp., posterior view.

FIGURES 9 – 14. Pregonopodal leg modifications of Idagona species. 9 – 12, third legs, anterior views. 9. Idagona westcotti, Giant Arch Cave. 10.. I. westcotti, Ice Capades Cave. 11. I. jasperi n. sp. 12. I. lehmanensis n. sp. 13. Leg 4 of I. lehmanensis n. sp., anterior view. 14. Denticles near adenostyle of leg 3 femur of I. lehmanensis n. sp.