Taxonomic Update and Habitat Status to Byttneria herbacea from Peninsular India

Byttneria herbacea is a threatened and endemic species to Indian Peninsular region. It was earlier placed in Sterculiaceae and then a separate family Byttneriaceae. As per APG classification, it is now treated in family Malvaceae. Endemic taxa are usually more vulnerable to anthropogenic threats, natural and climate changes, and therefore hold a higher extinction risk. Taxonomic study on endemic taxa improves a basic understanding for correct identification and description. Habitat and distribution study are essential to get specific information and interpretation on current status and population dynamics of the taxon including niche requirements. It mainly contributes to several branches of applied biology. Frequent botanical exploration work was undertaken to collect the Byttneria herbacea in the forests of Peninsular India and it was identified with help of various Floras. The present study provides the information to Byttneria herbacea, which includes a detailed morphological description with data on its relevant taxonomic notes, illustration, current distribution patterns with distribution map, habitats, ecological note, population size, conservation status and threats to the selected species. The present study is the first-ever attempt at studying the taxonomic and habitat distribution aspects of Byttneria herbacea in the Indian Peninsular region. This study helps for long-term conservation and management plan of Byttneria herbacea for foresters and researchers.


Introduction
Byttneria Loefling, named after David Sigismund A.

Materials and Methods
Frequent botanical explorations were carried out to document and collect the Byttneria herbacea, grown in deciduous forests to moistsemi-evergreen forests of Peninsular India. To know the correct identity of the collected specimens, the Flora of British India by Hooker [8], Flora of India (Sterculiaceae) by Malick [9], An Excursion Flora of Central Tamilnadu by Matthew [10], Flora of Maharashtra by Almeida [11], Envis Bulletin, Special habitats and threatened plants of India by Botanical Survey of India (BSI) Government of India, Ministry of Environment, Forest and Climate Change [12] and eFlora of India [13] were referred. Byttneria herbacea plant species identified after keen morphological and floral observations and perusal of literature. All relevant data were recorded in a field book along with photographs and herbariums.

Habitat
Byttneria herbacea is undergrowth herbaceous and rare species found mostly in scrubby deciduous forests to moist semi-evergreen bush land, often on gallery and woodland forest, stream banks or on termite hills. It is found growing most preferably at rocky terrain on red gravelly soils along the foot hills/slopes or forest edges, under thickets forest from 800-1100 Mt. above sea level. It is fast growing species which takes 1.5 -2.5 month/s to reach its reproductive stage. It shows narrow and restricted habitat range and localized by forming small cluster of its individuals. In population dynamics study of selected species in Maharashtra state, only 13 pockets of B. herbacea with small sub-population and less area of occupancy in its natural habitat have been observed. 328 Taxonomic Update and Habitat Status to Byttneria herbacea from Peninsular India

Distribution Pattern of Byttneria herbacea
Global distribution: Envis Bulletin [12] of Wildlife Institute of India, Dehradun, India and Singh et al. [15] Botanical Survey of India has recognized Byttneria herbacea is an endemic to the Indian Peninsular region.
Indian distribution: Byttneria herbacea is distributed in Andhra Pradesh, Assam, Karnataka, Kerala, Maharashtra, Madhya Pradesh, Nagaland, Orissa, Tamil Nadu, Telangana, Uttar Pradesh and West Bengal states of India. The selected species potentially occur in 12 states of India, but in reality, it has become threatened and restricted in very few forest pockets of Peninsular India with less number of occurrences and individuals in its sub-population.

Discussions
Endemic plants may actually be competitively inferior to other more widespread taxa [16]. The term endemic has a slightly different definition, depending on the author, e.g. according to Brown and Lomolino [17] when the term endemic is mentioned, it means that it simply does not occurs anywhere else, while in the same year Peterson and Watson in 1998 [18] stated that we should use endemic only when referring to a taxon that is restricted to a stated geographical region (either in natural or political borders). Since narrowly endemic species are threatened frequently [19] and since areas rich in endemism are more likely to be considered as a rich species area [20]. Narrow endemic species may harbour significantly lower genetic diversity at the population level than their widespread congeners [21][22]. Hence, endemic species may exhibit reproductive traits likely to reduce outcrossing rates, such as fewer and smaller flowers, less stigma-anther separation and lower pollen-ovule ratios [23][24][25]. The endemics constitute the foremost group of conservations.
A rare species is one that occurs in widely separated small sub-population so that inter-breeding between sub-populations is seriously reduced or restricted to a single population [26]. They are not at present endangered or vulnerable but face a high risk of being so and usually localized within restricted geographical areas or habitats or are thinly scattered over a more extensive range [27]. A hypothetical rare species is one with narrow habitat range, low climate tolerance; specialized adaptation requiring an outside agency for pollination, poor dispersal strategies, few seeds per fruit and poor viability of seeds [28]. Distribution study of threatened and endemic plant taxa provides insights for prioritizing such plant species conservation as well as processing the mechanisms of distribution patterns. Site containing national endemic and threatened species is more important for distribution study.
The outputs of floristic modelling and assessment can be used to improve understanding on conservation and protection of threatened plant species over the range in a suitable habitat [29] as well as identification of areas that represent biological species richness and endemic taxa [30]. Study on distribution and status of threatened and endemic species provides valuable data helps in conservation decisions for ecologists and conservationists. The ability to completely sample large areas in order to assess distribution is often difficult, hence smaller sampling areas to be used to make predictions about the distribution of a species over a larger area based on geographic and environmental predictor variables.
According to Cronquist [39] the order Malvales includes four polypetalous dicotyledonous families such as Malvaceae sensu stricto, Bombacaceae, Sterculiaceae and Tiliaceae. Bentham and Hooker [40] have placed Malvaceae sensu lato, Sterculiaceae and Tiliaceae families under the order Malvales. While Hutchinson [41][42] considered that the order Malvales should contain only Malvaceae as the order Malvales is more advanced than Tiliales and hence the families Sterculiaceae, Tiliaceae and Bombacaceae are treated under Tiliales. Bentham and Hooker [40] and Hutchinson [43] have placed the genus Byttneria (also spelled as Buettneria) under the tribe Byttnerieae in Sterculiaceae family but Takhtajan [44] has placed it under the tribe Byttnerieae of the subfamily Byttnerioideae of Sterculiaceae family.
Molecular phylogenetic studies (chloroplast ndhF gene-aligned length 2226 bp; rbcL sequence data) have shown that the traditional dicotyledonous families such as Malvaceae sensu stricto, Sterculiaceae, Tiliaceae and Bombacaceae are closely related and thus these families are merged into a more circumscribed family Malvaceae sensu lato under the core 'Malvales' (APG-III) [3]. Judd and Manchester [5] studies states that Malvaceae sensu stricto is monophyletic in origin while Bombacaceae, Sterculiaceae and Tiliaceae are not monophyletic which supports the view of Edlin [31]. As a result, those genera once placed under Sterculiaceae family are treated under subfamilies like Byttnerioideae. The members of Byttnerioideae clade show (i) a general reduction of stamen number compared to Grewioideae and other putative groups (ii) the fertile stamens are gathered into antipetalous fascicles and if staminodes present are antisepalous and (iii) the petals are broad or concave at their base. Further, the rbcL sequence data suggests that the separation of Byttnerieae and Theobromeae tribes of subfamily Byttnerioideae from the rest of traditional Sterculiaceae family as predicted by Edlin [31] is accepted by Whitlock, et al., [45], Alverson, et al., [46] and Bayer, et al., [36]. Based on stem structure, vegetative organs, flowers, schizocarpic fruit and spiny pollen grains character, Edlin [31] has created a new family Buettneriaceae by dividing the tribes traditionally placed in Sterculiaceae into two families: Sterculiaceae sensu stricto (Sterculieae) and Byttneriaceae (remaining tribes). Cronquist [39] however, stated that the Byttneriaceae is still quite heterogeneous (in morphology, anatomy, and pollen features) and is paraphyletic or polyphyletic. Thorne [47] has divided the family Sterculiaceae into two subfamilies namely Sterculioideae and Dombeyoideae. Thorne [47] system gives family status to Byttnerioideae and hence the subfamily Byttnerioideae is elevated to family level Byttneriaceae. Takhtajan [44] has also accepted this classification but he further subdivided these two subfamilies into a series of tribes. But the recent version of the Thorne

Conclusions
Habitat loss and unchecked business of wild endemic medicinal plants is threatening the future of essential resources, as well as the beauty, diversity and natural heritage of our green planet earth. As natural habitats are destroyed or degraded, we lose many unique and precious endemic species of plants every year from the wild habitat. This loss of diversity may also take with it important cures for diseases-both those face by us now and those that may emerge in the future. Conservation of existing wild habitat of endemic and threatened medicinal plant species are very essential to minimize or avoids the loss of these endemic plant resources. Sustainable use and ex-situ propagation and cultivation methods are already being The present study is the first-ever attempt at studying the taxonomic aspects and habitat distribution study of Byttneria herbacea in the Indian Peninsular region. This study helps for long term conservation and management plan of Byttneria herbacea for foresters and researchers. Further studies in view of embryological context are likely to yield more comprehensive results to improve fundamental understanding systematics of Malvaceae family members.