Caseya borealis Gardner & Shelley 1989

Shear, William A. & Leonard, William P., 2007, Additions to the milliped family Caseyidae. I. Caseya richarti, n. sp., and new records of previously described species in the genus Caseya Cook and Collins 1895 (Diplopoda, Chordeumatida, Caseyidae), Zootaxa 1524, pp. 23-34 : 31

Caseya borealis Gardner & Shelley 1989

Caseya borealis Gardner & Shelley 1989:231 .

The original localities given by Gardner & Shelley (1989) are included on the map (open symbols, Fig. 1 ). The type locality is 4 miles north of Shelton, Mason Co., Washington. Table 1 provides the new records, all of which are based on the inclusion of at least one mature male specimen in the sample. It is a point of interest that the Columbia River appears to form a definite southern boundary to the range of this species. The most northerly Oregon record for any Caseya is for C. megasoma in southern Tillamook Co., approximately 70 miles south of the river. Northeastern Oregon has been reasonably well-collected, and caseyids belonging to the genera Vasingtona Chamberlin 1941 , Opiona Chamberlin 1951 and Ochrogramma Gardner and Shelley 1989 have all been found there. Some of the same species of these three genera are also both north and south of the Columbia. It appears therefore that the gap in the distribution of Caseya species in northern Oregon, and the Columbia River as a barrier to the southerly dispersal of C. borealis are real phenomena. It would not be a surprise to find C. borealis on Vancouver Island; Opiona columbiana Chamberlin 1951 has a distribution in Washington similar to that of C. borealis , and the former species is found on Vancouver Island, the British Columbia mainland, the Queen Charlotte Islands and coastal Alaska ( Shelley et al. 2007)

Because these collections record only sexually mature individuals, they provide some hints of the life history of the species. Mature males first appear in the collections in September and October (single records in each month) become more abundant in November, December and January (7, 4 and 7 records respectively) and reach peak abundance in February (17 records) and March (10 records). Evidently some few males survive as late as June, when a single collection was made. These observations reinforce the point made earlier (i.e., Shear & Leonard 2003) that chordeumatidan millipeds in the Pacific Northwest of North America are active and mature in the cool, wet winter, passing the warm, dry summer as juveniles, possibly aestivating deep in the soil. Specimens were collected at altitudes ranging from 40 ft. (12.2 m) to 1294 ft. (394.4 m) above sea level (asl). Nearly all collections were associated with mixed forests including deciduous trees, and many were made close to streams, rivers, or other permanent sources of water.

All specimens listed in Table 1 will be deposited in the Field Museum of Natural History, Chicago (FMNH).

Figures

FIGURE 1. Map of Washington State, USA, showing distribution of Caseya richarti n. sp. (inverted triangles) and C. borealis Gardner & Shelley (filled dots are new records, open circles are literature records from Gardner and Shelley 1989).