Transactions British Mycological Society

NEW MELAMPSORIDIUM ON MAGNOLIA

SUJAN SINGH AND P. C. PANDEY

Forest Research Institute, Dehra Dun, India

During a disease survey in Darjeeling Forest Division, West BengalState, a rust was found on leaves of Magnolia campbellii occurring in anatural hardwood forest. It attacked leaves on the lower surface which wasalmost completely covered with pustules in severe infections. The affectedleaves turned pale green and were shed prematurely. The rust is con­sidered to represent an undescribed species of Melampsoridium.

Melampsoridium inerme sp.nov.Soris urediniosporiferis Havis, hypophyllis, sparsis, subepidermicis, erumpentibus;

peridio hemisphaerico, cellulis peridii ostiolaribus globosis vel ovoideis, 18-25 x 12-20pm, demum subpulverulentis, membrana 2'4--4-'3 pm crassa; urediniosporis subglobosis,ovoideis vel ellipsoideis, 17-28 x 12-20 pm echinulatis vel verrucosis, sessilis, episporiosubhyalino 1'2-2'0 pm crasso; soris teliosporiferis subepidermicis, immersis, pallidebrunneis; teliosporis unostratosis, prismaticis, Iateraliter arcteque coalitae, sessilis,Ieves, continuae, episporio circa I - I .5 pm crasso,

Hab. In foliis Magnoliae campbellii, Sinchal Range, Darjeeling, West Bengal, ix, 1969.F.R.I. 8177, Typus. Isotypus in Herb. K.

Uredinia cream buff, hypophyllous, hemispherical, scattered, peridiate,becoming powdery after dehiscence of peridium, subepidermal, latererumpent, 90-250 pm diam; peridium hyaline to very pale brown, lowerportion consisting of quadrangular, pentagonal to hexagonal cells,laterally fused, edges slightly pointed, 12-19 x 9-16 usn, wall 1'8-3'0 pmthick, upper dome cells globose, subglobose to ovoid, laterally somewhatloosely attached, comparatively thicker than the lower cells, 18-25 x 12-20pm, wall 2'4-4'3 pm; dehiscence of peridium occurs through formationof a hole or a crack in the dome cells through which urediniospores aredischarged; urediniospores pale yellow, subglobose, ovoid to ellipsoid,echinulate to coarsely warted, sessile, 17-28 x 12-20 pm, wall nearlyhyaline, 1'2-2'0 usx: thick.

Telia pale brown, subepidermal, not erumpent, becoming exposed ongermination, developing independently or sometimes within uredinia;teliospores nearly hyaline, one spore in depth, organized into a palisade­like layer beneath the epidermis, sessile,firmly united laterally, unicellular,cylindrical, 18-40 x 5'5-8'5 pm; wall pale brown, 0'9-1'5 pm thick.

The genus Melampsoridium is represented by four species, all of which arecharacterized by the presence of ostiolar cells of the uredinial peridiumextending into an acute or acuminate conical spiny apex (Cummins,1959; Hiratsuka, 1936). The telia in species of Melampsoridium are sub­epidermal, a single spore in depth and remain non-erumpent. In M.inerme, the general characters of the telia agree with those of previousMelampsoridium species but differ significantly in the cell morphology ofthe

Trans, Br. mycol, Soc. 58 (2), (1972). Printed in Great Britain

Notes and Brief Articles 343

Fig. 1. (A) Uredinial sorus showing urediniospores and peridium with lower quad­rangular cells and upper rounded cells (x 350). (B) Subepidermal telia with palisade­like layer of teliospores beneath the epidermis (x 800).

uredinial peridium. In M. inerme discharge of the urediniospores is effectedthrough a hole or crack in the dome of the peridium. The cells of the domebordering the hole or crack are round to subglobose, loosely attached anddo not extend into a spiny apex. In this character, the species resemblesMelampsorella but the telia in this genus are intra-epidermal as opposedto subepiderma1. As the telial character is considered to be more importantin delimitation of rust species, the present fungus is described as a newspecies of Melampsoridium. The new species is distinguished from all otherknown species of Melampsoridium in the absence of ostiolar cells of the

Trans. Br. mycol. Soc. 58 (2), (1972). Printed in Great Britain

344 Transactions British Mycological Societyuredinial peridium extending into an acute or acuminate conical spinyapex. In M. inerme, the epispore of the urediniospores is uniformly echinu­late, in which character it resembles M. hiratsukanum Ito but differs fromM. alni (Thum.) Dietel, M. betulinum (Desm.) Klebahn and M. carpini(Fuckel) Dietel where the epispore of the urediniospores is reported assmooth or naked at the apex (Hiratsuka, 1936).

Species of Melampsoridium are heteroecious and are known to havepycnial and aecial (0 and I) stages on Larix and uredinial and telial (IIand III) stages on members of the Betulaceae. It seems therefore that M.inerme, with II and III stages on Magnolia campbellii will alternate on a hostbelonging to the coniferae. In areas where M. inerme is now recorded,Cryptomeria japonica is the only species planted extensively and on which 0and I stages of the rust are likely to be present.

Sincere thanks are due to Professor G. B. Cummins for his valuableopinion on the identity of the rust and to the Director, Royal BotanicGardens, Kew, Surrey, England, for rendering the Latin diagnosis andsuggesting a new name of the species. Grateful acknowledgement is madeto Dr B. K. Bakshi, Forest Pathologist of this Institute for guidance in thework.

REFERENCES

CUMMINS, G. B. (1959). Illustrated genera of rust fungi. Burgess Publishing Co., Minne­apolis, Minnesota.

HlRATSUKA, N. (1936). A monograph of the Pucciniastreae, Memoirs of the TottoriAgricultural College 4, 1-374.

DELIMITATION OF AECIAL FROM UREDINIAL STATES

G. F. LAUNDON

Horticultural Research Centre, Research Division, Department ofAgriculture, Levin, New Zealand

In an earlier paper (Laundon, 1967) I modified the traditional systemof terminology of the spore states in the rusts partly by giving it a moredefinite morphological bias. The chief problem in both the traditionalsystem and my modified scheme arises in segregating the various sporestates amongst a welter of intergrading morphological forms and in par­ticular it is difficult to decide how to delimit the aecial from the uredinialstate. Previously I intuitively chose the catenulate and pedicellate methodsof spore formation as the sole basis for differentiating these states. Now Ipresent a formal justification for choosing this feature.

There are a number of features which are in various degrees charac­teristic of these states. First, one looks for features which invariably gotogether with their cytology and ontogeny. There are none. Secondly, onelooks for a pattern amongst combinations of features which might revealthat a certain feature is of more fundamental significance (i.e, more repre-

Trans. Br, mycol. Soc. 58 (2), (1972). Printed in Great Britain