96 Rowland M. Shelley 



Theatops phanus Chamberlin, 19516:101. Reddell, 1965:166. 

 Theatops spinicauda (nee Wood): Reddell, 1965:166. 



Type specimen. Holotype (NMNH) taken by G. G. Stevenson, 

 16 April 1926, from an unnamed cave on his ranch near Sonora, 

 Sutton County, Texas. 



Diagnosis. Ultimate tergite with complete median suture; ultimate 

 legs dorsally with a distomedial spur on each prefemur (Figs. 33- 

 34). 



Variation. The most striking variation in T. phanus involves its 

 adaptability to subterranean environments and the differences between 

 individuals from cave and epigean environments. Most of the cave 

 specimens that I examined were quite large, much longer and broader 

 than the surface specimens from Atascosa and Jim Wells counties, 

 which were small and similar in size to individuals of T. posticus 

 from southwestern deserts. Cave individuals also display troglobitic 

 modifications like pallid color and longer, narrower appendages. Their 

 antennae extend backwards to tergites 6-7; the antennomeres are three 

 to five times longer than wide; and the podomeres on the penultimate 

 legs are four to five times longer than wide. By contrast in epigean 

 specimens, the antennae reach back only to tergites 3-4; the antennomeres 

 are approximately twice as long as wide; and the podomeres on the 

 penultimate legs are only two to three times longer than wide. In 

 both cave and surface specimens, the dorsal and ventral edges (ridges) 

 of the flattened inner (medial) surfaces of the ultimate legs vary as 

 in T. spinicaudus. The dorsal edge varies from wavy and lightly scalloped 

 to highly irregular with variably minute teeth (Figs. 33-34), and on 

 the left prefemur of the individual from Menard County, the distalmost 

 tooth is almost as long as the adjacent spur (Fig. 34). Ventrally, all 

 specimens show at least one tooth on each prefemur (examples of 

 variation depicted in Figs. 35-38) and epigean specimens from Atascosa 

 and Jim Wells counties also have teeth on the femora (Figs. 36, 38). 

 As with T. spinicaudus, the medial borders of the coxopleurae exhibit 

 subapical pigmented spots, which are developed into teeth on the indivi- 

 dual from Williamson County (Fig. 37). 



Ecology. Chamberlin (19516) stated that the holotype was found 

 beneath a stone on the bottom of the first drop in the cave, and Reddell's 

 specimens (1965) were discovered along the banks of the stream in 

 Powell's Cave, Menard County. Because previous cave specimens display 

 elongated legs and antennae, classical adaptations to subterranean life, 

 T. phanus was thought to be exclusively troglobitic, but the epigean 

 specimens in Atascosa and Jim Wells counties lack these modifications. 

 The Terrell County cave specimen was found on silt 60 m (200 ft.) 



