208 PROCEEDINGS OF THE NATIONAL MUSEUM vol. los 



The laticollis phratry 

 Pachydesnius crassicutis laticollis (Attems) 



Figures 5,a,b, I0,d, 11, d 



Foniaria laticollis Attems, 1899, p. 258, pi. 13, fig. 312. 



Pachydesmus laticollis Pocock, 1909, p. 189. — Attems, 1938, p. 154, fig. 176. — 



Chamberlin and Hoffman, 1958, p. 44. 

 Pachydesmus retrorsus Loomis, 1943, p. 403. 



Type specimen: Male, in the Berlin Museum, labeled only "Illinois." 



Diagnosis: A medium-sized subspecies of the laticollis group, in 

 which the tibiotarsus is only 30 percent of the telopodite length, with 

 a small angulation on its leading edge; prefemoral process conspicu- 

 ously thickened at the geniculation and nearly straight in its distal 

 half; secondary tibiotarsus long, slender, and sinuous, with both its 

 tip and subterminal process slightly recurved proximad. The distal 

 margin of the receptacle of the cyphopod is straighter than in females 

 of other known forms, and the valves longer in proportion to their 

 height. Color in life medium to dark brown, with yellowish or testa- 

 ceous paranota. 



Variation: Despite the fairly large range occupied by this form, 

 there is no perceptible variation in gonopod structure or in other 

 details of body form. In the material studied the length varied from 

 62 to 70 mm., width from 12 to 14 mm. There is apparently some 

 geographic variation in size, with a decrease from south to north. 

 Specimens from the Tennessee River valley, in Marion County, Tenn., 

 and Jackson County, Ala., range from 66 to 70 mm. in length; those 

 from the Cumberland Plateau of central Tennessee from 62 to 65 mm. 

 Attems' type specimen is stated to be only 55 mm. long and 10 mm. 

 wide, considerably smaller than any I have examined. 



Remarks: Fortunately, although Attems' original drawing of the 

 gonopod of laticollis is made from low magnification and a difficult 

 aspect, the characters peculiar to the subspecies are clearly shown. 

 It is to be regretted that nothing is known of the history of the type 

 specimen, for it seems unusual that a scarce milliped from a relatively 

 remote area such as central Tennessee would find its way to the Berlin 

 Museum. The specimen, according to Attems, was originally labeled 

 "Fontaria virginiensis," although by whom is unknown. 



Distribution: This subspecies is known to occur from Jackson 

 County, Ala., north to Cumberland County, Tenn., chiefly through 

 the Cumberland Mountain Range but also to the west of it in the 

 Highland Rim area of central Tennessee. Presumably the great 

 bend of the Tennessee River marks the southern limits of the range. 

 Specimens have been examined from the following localities: 



Tennessee: Cumberland County: Grassy Cove, 12 miles southeast of Cross- 

 ville, 1 cf , Sept. 15, 1957, P. C. Holt (RLH). White County: Sparta, 1 c?, July 15, 



