The Chonaphini 125 



the caudal margin of the aperture is strongly elevated above the metazonal 

 surface and rises to a peak in the midline. The common valvular 

 surface is visible in situ; the receptacle lies beneath the medial corners 

 of the valves; and the operculum is closely appressed to their lateral 

 surfaces. All these structures are hirsute, the receptacles having long 

 hairs arising from the ventral margins and extending beyond the ventral 

 margins of the valves. As the receptacles in other eastern tribes are 

 glabrous, without even a trace of hairs, the hirsute ones enable females 

 of S. placidus to be distinguished from sympatric females of other 

 genera. In most chonaphines, the medial valvular margins project 

 distinctly ventrad, thereby creating a central depression or cavity on 

 the common, ventral surface (Figs. 8, 14, 20, 39, 49). Semionellus is 

 an exception in that the ventral surface is flat, without a trace of a 

 cavity or prolongation (Fig. 32), as is C. schizoterminalis, which has 

 central valvular lobes (Fig. 26). In keeping with its structurally different 

 gonopods, the cyphopods of Selenocheir have only slight suggestions 

 of medial lobes and central impressions (Figs. 58, 63, 67). Likewise, 

 the receptacle is alate in most species, being cupped below the medial 

 corners of the valves, narrowing distinctly in the midline, and extending 

 for varying lengths along the anterior and posterior sides of the valves. 

 For the most part, the operculum is relatively large, a distinct sclerite 

 lateral to the valves, instead of an indistinct structure as in most 

 xystodesmids. 



^ Tribe Chonaphini Verhoeff 



Chonaphinae Verhoeff, 1941:403. 



Chonaphini: Hoffman, 1979:157. Shelley, 1990:2313-2315. 



Components — Chonaphe Cook, 1904; Semionellus Chamberlin, 

 1920; Montaphe Chamberlin, 1949; Tubaphe Causey, 1954^; Metaxycheir 

 Buckett and Gardner, 1969; Selenocheir, new genus. 



Diagnosis — A tribe of moderate-size Xystodesminae with the 

 following characteristics: gonopodal aperture with caudal margin ele- 

 vated, ovoid or extending caudad to varying degrees between 9th 

 legs, sternum between latter present as "shelf" in caudal extension; 

 gonocoxae joined by membrane, with or without sclerotized sternal 

 band, latter usually with lobes subtending coxae, occasionally with 

 medial lobe; telopodal elements parallel or not parallel; prefemoral 

 process variable, often elaborately ornamented, short and less than 

 half as long as acropodite or as long or longer than latter, ranging 

 from acicular to narrowly blade-like to expanded and laminate, usually 

 with projections arising from stem or with shallow or deep apical 



