Millipeds of Genus Brevigonus 59 



TYPE LOCALITY. Anderson Co.— 12.6 km. (7.9 mi.) SE Anderson, 

 along SC hwy. 459 at Rocky R., M, F, 7 May 1977 (NCSM A1550); 

 10.1 km. (6.3 mi.) NE Iva, along SC hwy. 413 at Rocky R., 2M, 2F, 1 1 

 June 1978, R. M. Shelley and W. B. Jones (NCSM A2066); and 6.4 km. 

 (4 mi.) SW Iva, along unnumbered rd. off SC hwy. 187 at Generostee 

 Cr., M, 7 May 1977 (NCSM A1549). Abbeville Co.— 5.8 km. (3.6. mi.) 

 SE Lowndesville, along SC hwy. 232 at Deal Cr., M, F, 6 May 1977 

 (NCSM A1544); and 4.2 km. (2.6 mi.) SW Lowndesville, along SC hwy. 

 70. 0.5 km. (0.3 mi.) SW jet. SC hwy. 64, M, 6 May 1977 (NCSM 

 A 1545). 



Remarks. — The unusually large process of the 4th sternum, the long- 

 est of any apheloriine milliped known to me, is one of the key features 

 of arcuatus. The structure is also longer than the widths of the adjacent 

 coxae in two species of Croatania (Shelley 1977), but in these forms it is 

 apically divided and bent anteriad. In arcuatus, the process projects 

 directly ventrad and is not divided, although there is a very slight apical 

 indentation. The process is shaped similarly in shelfordi but is shorter, 

 being subequal in length to the coxal widths. A long 4th sternal process 

 is thus characteristic of the genus. 



Of interest is the fact that, except for Sigmoria tuberosa Shelley in 

 the mountains of Swain County, North Carolina, the longest 4th sternal 

 processes in the tribe Apheloriini are found in species in the Piedmont 

 Plateau, and mostly in South Carolina. Hoffman (1967, Fig. 4) showed 

 that the structure is longer than the adjacent coxal widths in Cleptoria 

 abbotti Hoffman, which occurs along the southern side of the Savannah 

 River in piedmont Georgia, but otherwise all species demonstrating this 

 condition occur north of the river. However, not all the apheloriine mil- 

 lipeds in South Carolina are so well endowed. The process is shorter 

 than the widths of the adjacent coxae in Sigmoria latior (Brolemann), 

 Cleptoria macra Chamberlin, and all three species of Furcillaria; and is 

 subequal in length in Sigmoria quadrata Shelley and S. laticurvosa 

 Shelley (Shelley 1981a, 1981b; Hoffman 1967). Consequently, enlarge- 

 ment of this process seems to have evolved independently in four dis- 

 tantly related genera (Cleptoria, Croatania, Sigmoria, and Brevigonus). 

 Or could this be an ancestral trait that has been retained by certain 

 species in these genera? At present we have insufficient information on 

 other apheloriine taxa to answer this question, since past authors have 

 largely ignored the configuration of the 4th sterna. Having observed 

 sternal variation in many species, however, I incline toward the latter 

 interpretation and suggest that the length, and possibly also the shape, 

 of the 4th sternal process might be indicators of distant phylogenetic 

 relationships. The 4th sternum certainly warrants more attention than it 

 has received, and other authors are encouraged to examine and illus- 

 trate it in their species so we will be better able to interpret its signifi- 

 cance through a more complete knowledge of variation. 



