Observations on fertile populations of two Porella ( Porellaceae , Marchantiophyta ) species from Kumaun Region in the Western Himalaya , India

The unrecorded androecia and feebly described gynoecia in Indian specimens of two Porella species, namely, P. densifolia subsp. appendiculata (Steph.) S. Hatt. and P. campylophylla var. ptychantha (Mitt.) F. Shaheen & S.C. Sriv., collected from Kumaun region in the state of Uttarakhand in Western Himalaya, are being described and compared besides observing variations in vegetative features of the plants.


Introduction
In course of survey of the liverwort flora of Kumaun Region in the State of Uttarakhand in Western Himalaya, we came across two profusely fertile Porella species, namely, P. densifolia subsp.appendiculata (Steph.)S. Hatt.and P. campylophylla var.ptychantha (Mitt.)F. Shaheen & S.C. Sriv.during the winter months in 2014.It was heavily snowing for more than a week when we collected these specimens.While population of the former species was observed at Dhobi Ghat (29 0 25' 17.4" N; 79 0 26' 2.5"E; 2031 m), the population of latter species was noted at Mukteshwar (29 0 28' 29" N; 79 0 38' 45.3"E; 2269 m) -both localities in Nainital district.It is interesting to note that in our earlier collection tours made during summer and post rainy months of the year, we could find only the sterile specimens of the species, though from different localities in this region.In fact, the population of Porella, a dioecious genus, is seldom observed in a fertile state.
A perusal of literature showed that the two taxa are purely tropical and largely Himalayan.While P. densifolia subsp.appendiculata (Steph.)S. Hatt. in India (besides Nepal and China, see Hattori, 1966 andBapna andKachroo, 2000) is largely confined to Western Himalaya, the other taxon, namely, P. campylophylla var.ptychantha (Mitt.)F. Shaheen & S.C.Sriv., is recorded both from Western and Eastern Himalaya (Singh and Singh, 2006).Kashyap (1932) in his monumental work on "Liverworts of Western Himalaya and Panjab Plain" has described the former species as Madotheca appendiculata Steph., yet their description lacks the ISSN: 2348ISSN: -1900 Horizon e-Publishing Group details of the androecia and those of the sex organs.So is the case with the description of the latter species by Shaheen and Srivastava (1989).In order to fill the gap of details of androecia and to provide additional information on gynoecia and sporophyte structures, an effort to describe the two species has been made.

Habitat and Ecology:
The species grows on the bark of oak tree, Quercus leucotrichophora A Camus. associated with some pleurocarpus mosses in very moist conditions.Distribution: Endemic to Himalaya.Eastern Himalaya -Kurseong, Pynursala; Western Himalaya -Loharkhet.(Shaheen and Srivastava, 1989).This is the second record of the taxon from Western Himalaya.

Instituted as Madotheca appendiculata by Franz
Stephani in 1910 from the 'type' locality Mussorie in Western Himalaya, the species is currently recognized as Porella densifolia subsp.appendiculata (Steph.)S. Hatt.Kashyap (1932) has described and illustrated the taxon excluding the details of the androecia.The species is large-sized and a robust epiphyte of common occurrence in Western Himalaya.We have made several collections of the taxon but always in a sterile state until recently when we observed the population in a copiously fertile state during the winter months.The species can be distinguished by its golden brown colour, the ventral margin of the leaf-lobe nearly straight (an angle of 80-90 0 from the axis), basal appendages of the underleaves and leaflobules being remarkably developed with irregularly lacinulate-toothed appendages and leaves and underleaves not so densely imbricate.
Our observations on the fertile parts of the population of P. densifolia subsp.appendiculata (Steph.)S. Hatt.include the presence of numerous androecia on primary or secondary branches in a bipinnately branched male plants, the presence of 6-9 pairs of imbricate and deeply concave male bracts, the presence of a single spherical antheridium in each bract, the presence of large campanulate perianth surrounding 3-8 terminal archegonia.
The second taxon, P. campylophylla var.ptychantha (Mitt.)F. Shaheen & S.C.Sriv. is based on the 'type' specimen collected by J. D. Hooker from Sikkim in the Eastern Himalaya and instituted as Madotheca ptychantha by William Mitten in 1861.Sinske Hattori (1971) initially made it Porella ptychantha (Mitt.)comb.nov.and later, in 1978, synonimized it with Porella campylophylla (Lehm.& Lindenb.)Trevis.However, Shaheen and Srivastava (1989) have resurrected the taxon and on the basis of certain notable distinguishing features gave it the status of a variety.The var. ptychantha may be distinguished from the var.campylophylla in having leaf-lobes with blunt and reduced teeth vs. leaf-lobes with sharp teeth, the base of the leaf-lobule being shortly decurrent vs. leaf-lobule and underleaves bases being longly decurrent, widely ovate underleaves vs. oblong ovate underleaves and the crenulate margin of the perianth plicae vs. smooth margin of perianth plicae.
We noted in fertile populations of P. campylophylla var.ptychantha (Mitt.)F. Shaheen & S.C.Sriv.that the androecial branches are longer and always arise from the primary axes; the spherical to ovoid antheridia are 1 or 2 per bract; gynoecia develop on primary and secondary axes both, with one pair of bracts and a single bracteole; perianth 7-8 plicate, crenulate, elliptical; mouth of the perianth is minutely dentate; narrowly incurved ventral margin of the leaf-lobe; simple or branched elaters; and the papillose spores in addition to the varietal features mentioned before.
The fact is that the two species mentioned above are copiously fertile during the intense winter months, at least in this part of the world.

Competing Interests
The competing interests of the present research paper include (i) the understanding of taxonomy of two Porella species with the aid of additional information on androecia and gynoecia; and (ii) the observation of the fact that the reproductive structures in both taxa appear only when the atmospheric temperature is very low.

Authors' Contributions
MR conceptualized the idea of the research paper and identified the specimens; PS discussed the ecology of the described taxa and suggested some valuable points on their comparison; and, SNS coordinated the work, interpreted the results and drafted the manuscript after thorough discussion with other two authors.All authors read and approved the final manuscript.