Morphometric Study of Musanga cecropioides R. Brown and Myrianthus arboreus Palisot

: Morphometric or Numerical taxonomic analysis of 56 quantitative and qualitative characters, obtained from Musanga cecropioides R. Brown and five species of Myrianthus , M. arboreus Palisot de Beauvois, M. holstii Engler, M. libericus Rendle, M. preusii Engler and M. serratus (Trecul) Bentham was carried out by calculating similarity and distance indices followed by cluster analysis and construction of a dendrogram for visual appreciation of the taxonomic relationship among these species. The dendrogram showed close similarity among the Myrianthus species, with Musanga cecropioides clearly distinct from the Myrianthus species. This confirms the monotypic status of Musanga , with only one species, Musanga cecropioides .© JASEM

In Engler's (1889) classification of the Moraceae, the two African genera, Musanga and Myrianthus, together with the neotropical genera, Cecropia Loefl., Coussapoa Poepp. & Endl. and the Asiatic genus, Poikilospermum Zippelius ex Miguel., constituted the subfamily Conocephaloideae (Ruiter, 1976). Corner (1962), transferred the whole subfamily to the Urticaceae. However, Wee-Lek (1963), suggested an even more unnatural system of classification based on fruit size. He placed Musanga and other microspermous genera of the Conocephaloideae in the Urticaceae leaving the megaspermous genera including Myrianthus in the Moraceae. The classification of Corner (1962) had support from various workers using evidence from such systematic lines of evidence as gross morphology and phytochemistry (Ruiter, 1976;Ojinnaka et al., 1986). Berg (1978), proposed the new family, Cecropiaceae, to incorporate the genera, Musanga and Myrianthus based on morphological characters, pointing out that they apparently form a natural coherent group distinct from members of the Moraceae and Urticaceae.
The confused taxonomic history of Cecropiaceae (Setoguchi et al., 1993) reflects the fact that Cecropiaceae is intermediate between the Moraceae, with which they share possession of lactifers, and the Urticaceae with which they share orthotropous subbasal or basal ovule (Berg, 1978;Takhtajan, 2009).
The isolation of tormentic and euscaphic acids from Musanga and Myrianthus and their absence in other genera of the families, Moraceae and Urticaceae (Ojinnaka et al., 1984(Ojinnaka et al., , 1986, provided a chemical systematic line of evidence in support of Berg's (1978) proposal for a separate family Cecropiaceae for the genera, Musanga and Myrianthus.
Morphometrics also known as Numerical taxonomy can be defined as the quantitative analyses of biological form. It has been widely used in a lot of disciplines including Systematics (Henderson, 2006). Morphometrics or Numerical taxonomy is the application of various mathematical procedures to numerically encode characters.
This practice integrates data from a wide variety of sources such as anatomy sensu lato, chemistry, cytology, ecology, genetics, geography, palynology, physiology etc. (Soladoye et al., 2010). Actual morphometric or numerical taxonomic studies of plant taxa were very scarce before the 1960s (Dogan et al., 2009). The product of this exercise is usually accepted as unbiased and therefore objective and used to classify or place * 1 ARUSURAIRE, JO; 2 NYANANYO, BL taxa in an appropriate and acceptable hierarchy (Quike, 1993). Morphometrics or Numerical taxonomy has previously been applied in the classification of a number of plant taxa (El-Gazzar, 2008;Dogan et al., 2009;Soladoye et al., 2010).
In this investigation, morphometrics or numerical taxonomy (which is not a systematic line of evidence) has been applied to clarify the doubtful taxonomic status of Musanga cecropioides and five species of Myrianthus, based on quantitative and qualitative characters.

MATERIALS AND METHODS
Musanga cecropioides R. Brown and five (5)  holstii Engler, M. libericus Rendle, M. preusii Engler) and M. serratus (Trecul) Bentham) were grouped by cluster analysis using the un-weighted pair group method analysis (UPGMA) based on the similarity matrix of Euclidean distances of 56 quantitative and qualitative characters. The characters were selected without prejudice. These characters obtained from the leaf, habit, stem, flower and fruit structure, seed, chemical components (leaf and stem), anatomy (leaf and stem), pollen morphology, and ecology were placed under ten headings (Table 1).To trace the relationship among the taxa studied, the data were standardized before clustering and a dendrogram was constructed. The statistical analyses were performed using the PAST software.

RESULTS AND DISCUSSION
In the present study, six taxa were evaluated on the basis of data matrix generated from 56 quantitative and qualitative characters (Table 1). A similarity matrix based on Euclidean distances for the six taxa is presented in Table 2. The constructed dendrogram * 1 ARUSURAIRE, JO; 2 NYANANYO, BL based on the Euclidean distances from the data matrix (Appendix 1) divides the taxa into three clusters, viz. cluster G 1 and subclusters SG 1 and SG 2 (Figure 1).