192 Rowland M. Shelley 



main ranges; the former is thus the southernmost chonaphine in the 

 West, and the latter, the northern- and eastern-most. 



Chonaphe armata and S. placidus are the species with the most 

 interesting distributions; they occur in five and four areas, respectively 

 (Figs. 68, 69). In both cases, an ancestral range has fragmented, leaving 

 allopatric populations that have undergone little anatomical divergence 

 and are hence conspecific. Additionally, the distances between the 

 five populations of C. armata are much greater than those between it 

 and C. remissa, which is effectively parapatric, being segregated only 

 by the Columbia River and the spine of the Cascade Mountains. Chonaphe 

 remissa replaces C. armata west of the Cascades in Washington, as 

 the latter occurs only on their eastern slope, but in Oregon, C. remissa 

 is absent, and C. armata occurs only west of the Cascades, in the 

 lower Willamette Valley and eastern foothills of the Coast Range as 

 far south as Benton County. Chonaphe evexa is thus an allopatric, 

 southern species, detached from the main generic range by some 125 

 mi (200 km); C. schizoterminalis, in northeastern Washington, is essen- 

 tially parapatric with a population of C. armata. 



The picture at the generic level (Fig. 71) is identical to that at 

 the specific, with the exception of Selenocheir in California and Chonaphe 

 in Washington. Selenocheir covers a broad area in southwestern Oregon 

 and northern California with a finger extending southward through 

 the Sierra Nevada foothills. In Chonaphe, the ranges of C. armata in 

 western Washington and Oregon join with that of C. remissa to form 

 a large area with a finger extending southward down the eastern slope 

 of the Coast Range and the western Willamette Valley. Ranges are 

 also mutually exclusive except in Idaho and environs, where they 

 overlap as in the species. 



RELATIONSHIPS 



Tribal — What seemed to be a straightforward study from such 

 specialized genera as Chonaphe and Semionellus, with their apomorphic 

 acicular acropodites and elaborate prefemoral processes, rapidly became 

 complex as I pondered forms like T. levii, Montaphe paraphoena, and 

 Metaxycheir prolata, and the meaning and significance of such inconsis- 

 tencies as the presence of lateral versus medial sternal lobes, and the 

 presence or absence of a sternum. Because the acropodites of its 

 species are as narrowly blade-like or acicular as those of T. levii and 

 M. prolata, the question arose as to whether Selenocheir is also a 

 chonaphine, but with a short, instead of a long, prefemoral process. 

 No other established tribe can accommodate Selenocheir, and a monobasic 

 category would be undefinable, so I place it in the Chonaphini. Selenocheir 



