488 
J. C. ARTHUR 
A common short-cycle rust of American tropical regions, extending 
well north and south into the temperate zones. The first host men- 
tioned is a new one for the rust. 
176. Puccinia eximia Arthur & Holway sp. nov. (on Rubiaceae). 
Galium mexicanum H.B.K. (?), Antigua, Dept. Sacatepequez, 
March i, 1916, i, III, 542. 
Galium sp., Volcan de Agua, 7000 feet alt., Dept. Sacatepequez, 
Jan. 13, 1915, I, ii. III, 81 \ Antigua, Dept. Sacatepequez, Dec. 
28, 1916, I, III, 645] Quezaltenango, Jan. 16, 1917, I, II, iii, 
735 (type);same, Jan. 31, I9«[7, I, \l\,8o9. 
Aecia amphigenous, more or less scattered upon rather indefinite 
yellowish areas, short cylindric, 0.2-0.5 mm. high, 0.2-0.4 mm. in 
diameter; peridium white, the erose margin soon breaking away, the 
peridial cells rhombic or rhomboidal, 16-23 by 23-40 ^i, slightly over- 
lapping, the outer wall striate, 3-7 jjl thick, the inner wall verrucose, 
2.5-5 M thick; aeciospores irregularly globoid or ellipsoid, 18-21 by 
ix \ wall colorless, thin, 1-1.5 At» finel}^ and closely verrucose. 
Uredinia hypophyllous, scattered, oval or oblong, 0.6-1 mm. long, 
somewhat tardily naked, pulverulent, dark cinnamon-brown, ruptured 
epidermis conspicuous; urediniospores elHpsoid or obovoid, 21-29 by 
.32-35 iJL\ wall dark cinnamon-brown, moderately thick, 2-3 ijl, coarsely 
echinulate, the pores 2-3, superequatorial. 
Telia hypophyllous, scattered or in small groups, oval, 0.6-0.8 mm. 
long, early naked, compact, dark chestnut-brown, ruptured epidermis 
noticeable; teliospores oblong, clavate-oblong, or clavate-ellipsoid, 
21-27 by 42-58 //, round at both ends, or somewhat narrowed below, 
slightly constricted at septum; wall golden- or pale chestnut-brown, 
1.5-2 }x thick, thicker above, 5-12 11, smooth; pedicel colorless, about 
as long as the spore. 
No pycnia were detected in the collection examined. The species 
differs from other Galium rusts having uredinia by the large uredinio- 
spores with their two or three superequatorial pores. The teliospores 
are also unusually large. In part of the collections uredinia were 
absent. When only aecia and telia are present there is a resemblance 
to P. amhigua, but this form differs by the naked telial sorus and lighter- 
colored teliospores, with their ends more rounded. The teliospores 
are also noticeably broader, and usually somewhat larger. A eugyrini- 
ous species in which the uredinia are slightly or not developed is not 
unknown, although somewhat rare. The malvaceous rust Puccinia 
heterospora, common in California, not infrequently shows this be- 
havior. 
