134 
Rowland M. Shelley 
Although O. gracilipes was officially named and described by 
Loomis (1971), its existence was first mentioned by Hoffman (1969), 
who called it an undescribed and possibly relictual representative of 
the Hirudisomatidae in the high mountains of North Carolina, Georgia, 
and Tennessee. 
Mexiconium, new genus 
Type species — Mexiconium absidatum, new species. 
Diagnosis. Dorsum smooth and glossy, polished, with broad, dark 
middorsal stripe arising on collum and terminating on penultimate 
segment; body narrow (W/L ratio 16.7%) and vaulted in profile, sides 
not extending laterad; metaterga with caudal margins slightly elevated 
but not upturned; collum moderately broad, over-hanging epicranium 
and part of one pair of ocelli; telson broad, comprising entire breadth 
of caudal extremity; sternum of anterior gonopods with strong, sparsely 
hirsute lobes, widely separated from each other; anterior gonopod curving 
strongly anteriad distad, ultimate podomere with lightly hirsute lobe 
ventral to and overhanging glabrous dorsal branch, latter long, narrow, 
and acuminate, extending nearly directly laterad; corners of 4th and 
5th podomeres slightly extended on caudal side, latter expanding distad 
and subuncinate; coxa with broad, glabrous lobe on anterior side, apically 
rounded; posterior gonopod with ultimate podomere simple and acicular, 
apically trifurcate. 
Species — One is known; others may exist in remote pockets in 
the Sierra Madre Oriental. 
Distribution — Known only from the type locality of the one component 
species in Vera Cruz, Mexico. 
Fig. 30. Relationships in Octoglena. 
