184 
Psyche 
[June-September 
Diagnosis. Trochosa terricola is like other Nearctic species of 
Troehosa in color pattern (compare Figs. 1, 2 with 3-6) and mor¬ 
phological features such as the eye arrangement and relative length 
of legs compared to carapace length. Males of terricola differ from 
other Nearctic species of Trochosa in structure of the palpus (com¬ 
pare Figs. 28-31 with Figs. 32-37, 39, 40, 42, 43, 45, 46). The most 
distinguishing feature of the palpus in terricola is the loop at the 
distal end of the embolus (Fig. 30). Females of terricola differ from 
other Nearctic species of Trochosa in structure of the epigynum. 
The transverse piece of the epigynum in terricola does not have the 
ends curved anteriad as in avara, gosiuta, shenandoa, and parthenus 
(compare Figs. 10-16 with Figs. 7-9, 17-27). Trochosa terricola 
forms together with spinipalpis, robusta, and ruricola of Europe a 
close-knit species group. There is a great anatomical similarity 
among these species and a definitive study of the middle European 
species of Trochosa (Engelhardt 1964) did not reveal any ecological, 
seasonal, or ethological isolation mechanisms present. These four 
species occur sympatrically throughout western and central Europe. 
In spite of morphological, ecological, and behavioral similarities, no 
hybrids could be produced in the laboratory. Engelhardt suggests 
that physiological mechanisms (pheromones) may prevent hybridi¬ 
zation between these species. 
Map 1. Collection localities for Trochosa terricola showing distribution of poste¬ 
rior cheliceral teeth. Alaskan and northern Canadian localities not on map are listed 
under Records and marked with asterisks. 
