The family Menispermaceae is divided in two large clades, with the tribes Tinosporeae and Menispermeae included in clades 1 and 2, respectively. Molecular phylogeny was studied using five characteristics either from the flower, i.e., using the androecium and style scar, or from the seed, i.e., using the endosperm, cotyledons, and shape (Ortiz et al. 2007; Jacques and Bertolino 2008). According to the previous reports, among the seven genera in this study, the synandrium in the central column with horizontal anthers is a synapomorphy of three genera, i.e., Cissampelos, Cyclea, and Stephania, but in four genera, i.e., Cocculus, Pericampylus, Sinomenium, and Tinospora, there are no synandrium. The position of the style scar is terminal in the genus Tinospora and basal in the other six genera. Endosperm is present in all seven genera. The cotyledons are foliaceous in Tinospora and fleshy in the other six genera. The seed shape is straight in Tinospora and crescent in the other genera.
The ancestral conditions for Menispermaceae are synapomorphies of foliaceous cotyledons, no synandrium, and the terminal position of the style scar (Jacques and Bertolino 2008), as well as straight-shaped seeds (Ortiz et al. 2007). In this study, we suggest that the morphological phylogeny of the genus Tinospora is the most original condition among seven genera in Taiwan because of foliaceous cotyledons, terminal style scar, and straight-shaped seed; the genera Cissampelos,
Cyclea, and Stephania are derived from Cocculus, Pericampylus, and Sinomenium because of a synapomorphy of no synandrium.
The three genera, Cissampelos, Cyclea, and Stephania, form a clade (S–C–C clade, or pantropical clade in Herrera et al. 2011) that is strongly supported as monophyletic, which has female flowers with a single carpel as a morphological synapomorphy (Wefferling et al. 2013). Furthermore, the endocarps of the three genera are variously ornamented with spines, tubercles, wings, or ridges; distal limb is longer (rarely equal), and sometimes has two (to four) lateral chambers. These chambers can have lateral apertures or not; the vascular trace is ventral; the condyle is compressed bilaterally or both bilaterally and dorsoventrally, and is sometimes perforated (Wefferling et al. 2013).
Cissampelos and Cyclea are closely related to Stephania (Hoot et al. 2009; Jacques et al. 2011), but their endocarps are easily distinguished. In Cissampelos and Cyclea, there are always two lateral crests (ridges) per side, usually two dorsal crests, and their endocarps are often imperforated. According to published results (Jacques 2009; Liu and Jacques 2010; Herrera et al. 2011), endocarps of Cissampelos pareira L. are covered by conspicuous spines with two dorsal and lateral ridges (crests). They also have a distinctly longer distal limb that slightly comes closer, and the outer lateral ridge partly overlaps the inner one (all ridges bear outgrowths). Ortiz and Nee (2014) described a new species of Cissampelos arenicola M. Nee & R. Ortiz. Its endocarp length and width are about 6 × 7 mm, and it is suborbicular-bilaterally compressed, with one small circular perforation on the lateral faces. Furthermore, its ornamentation is obscure, consisting of a very low medial ridge and faintly transverse ridges. In this study, the endocarp of C. pareira var. hirsuta was found to be horseshoe-shaped, with one circular perforation, and one dorsal and lateral ridge (Table 1; Figs. 1–3) that are more or less similar as in C. arenicola, but truly differ from those of C. pareira. This might be due to intraspecific differences, or because we included immature fruits that had not yet developed those characteristics. However, because of the low number of specimens known for some species (e.g., only two fruits were collected), this study did not consider any intraspecific variability for endocarp shape and size. Therefore, collecting and studying more mature fruits might resolve these inconsistencies in endocarp characteristics.
Forman (1986) and Thanikaimoni (1986) describe in detail that Cocculus showed a formation of dome–shaped extensions of the lateral ridges over the median septum that create a two–chambered condyle. The diagnostic characters of Cocculus included lateral faces of endocarp without aperture, or with aperture or perforation centered in the lateral concave face. Lateral chambers are present, as well as a surface with longitudinal and transverse ridging. Finally, a lateral compression that is restricted to center of each lateral face results in a subannular endocarp (Wefferling et al. 2013). Furthermore, Jacques (2009b) reported an endocarp morphological description of C. laurifolius, C. orbiculatus, and those of the genus Cocculus. When comparing the figures and terms used in the previous reports for these two species in Taiwan, we observed differences in the characteristics of the subannular shape, the formation of lateral chambers without aperture, a reticulated surface, and their obscure ventral trace (Figs. 6–13), whereas the other characteristics were consistent with the previous results described as above.
Jacques (2009b) included the concave exterior of laterally compressed endocarps as part of the condyle, and referred to a double external condyle in descriptions of several taxa, including Cissampelos, Cocculus, Cyclea, Pericampylus, and Stephania. In this study, the endocarps of three species, C. gracillima, C. insularis, and C. ochiaiana (Figs. 1–18, 19–28) are consistent with the characteristics described as above, because they have two dorsal and two lateral ridges, and two lateral chambers combined with a condyle aperture on the ventral view. Liu and Jacques (2010) indicated that the genus Cyclea bears two dorsal crests with 16 small spines, but there are about 25 spines in C. insularis. The latter might be an intraspecific difference or influenced by the measuring method. Wefferling et al. (2013) indicated that the endocarps of the genus Cyclea show a variety of ornamentation, with two to four lateral chambers with or without lateral apertures. In the present study, we found that three species in Taiwan display a lateral aperture with different chamber sizes, especially the endemic species C. insularis (Figs. 24, 27).
The endocarp of P. glaucus shows a lateral concavity (i.e., condyle) a broader dorsal ridge at one limb, a ventral vascular trace, concave lateral faces with convex sculpturing near ventral notch, and long spines or very thick spines (Jacques 2009b; Herrera et al. 2011; Wefferling et al. 2013). The characteristics described above are consistent with the species in Taiwan (Figs. 29–33). The species Pericampylus formosanus Diels was placed as the synonym of P. glaucus (Lo et al. 2008), but the former can be differentiated from the latter by the covering hairs on both surfaces of the leaf and the filaments united into a tube (Huang and Huang 1996). Future comparative studies on hairs, filaments, and endocarps between these two species might provide strong evidence for the synonym treatment.
The endocarp lateral faces of the genus Sinomenium show a conspicuous off-center aperture near distal limb (Wefferling et al. 2013), and S. acutum (Herrera et al. 2011) and S. acutum var. cinereum (Wefferling et al. 2013) have spines on the dorsal ridge. Jacques (2009b) also indicated that the double external condyle of S. acutum is not perforated, makes a large central area with a conspicuous hollow near one limb, and has a comma-shaped ridge bordering it. The position of this hollow and the aperture is as same as the one near the limb, but these two researchers describe it by different terms. A personal communication with Dr. Jacques indicated that the aperture must be connected to a subglobose condyle, such as in the genus Tinospora. He furthermore suggested that, for the genus Sinomenium, it should be called a vascular trace (Table 1). The vascular trace was indeed observed in S. acutum, but the spines were not in this study (Figs. 34–37). The key to the genera of Menispermaceae indicated that the number of lateral ridges of Sinomenium is <25, and that of Menispermum is >26 (Jacques 2009b), and the number of lateral ridges of species in Taiwan is >26. Liu and Jacques (2010) compared fossil endocarps with extant species of S. acutum and Maianthemum canadense L. In their study, the number of protuberances (i.e., lateral ridges) for S. acutum ranged from 18 to 21, and showed ventral notch that was straight or slightly concave, whereas those of M. canadense L. ranged between 27 and 30, and the ventral notch was V-shaped. Furthermore, the ornamentation of endocarps of Menispermum has no spines on the dorsal crest, the number of lateral ridges is >26, and the ventral notch is almost V-shaped. We therefore question if the species S. acutum in Taiwan is misplaced and similar to the Menispermum genus. This inconsistency should be addressed with further sampling data.
The endocarp dorsal ridges of the genus Stephania are discontinuous, with a strong ornamentation that has an intrageneric variation, namely in the transverse ridges, and in the condyle perforation (Jacques 2009b). In this study, the genus Stephania displays the crustaceous, transverse ridging that is different from Cissampelos and Cyclea. Transverse ridges of endocarps are found in S. cephalantha, and S. tetrandra (Figs. 38–43, 60–64), whereas transverse strips are found in S. japonica, S. longa and S. merrillii (Figs. 44–59). The other lateral face characters in this genus are consistent with the previous results (see Table 1). Concave lateral faces are present, and have a convex sculpturing near the ventral notch in S. tetrandra (Fig. 60). This character is only found in the genus Pericampylus (Wefferling et al. 2013).
The endocarp of the genus Tinospora is bony, round, ovoid/obovoid, or subellipsoidal in outline, tuberculate or verrucose, sometimes echinate, hispid (with stiff bristles), or ornamented with wings and ridges. The lateral chambers are absent, the vascular trace is positioned inside the ventral concavity of the condyle and forms a cylindrical, protruding vascular tube extends nearly to the level of the aperture mouth; the condyle is hollow, deeply intrusive, and subglobose or subreniform, and it is open ventrally (Wefferling et al. 2013). In the present study, the endocarp of T. dentata, which is an endemic species in Taiwan (Hengchun Peninsula), is round in shape with a developed keel at the apex on the dorsal ridge, and a linear condyle aperture; the condyle is subglobose in shape (Fig. 69), with a cupule and locule, and a protruding vascular tube. Lo et al. (2008) did not report this drupe information, and this is the first description and photographs for the endocarp of T. dentata (Table 1; Figs. 65–69) providing some evidence and references for further studies.
Birds and mammals are the most commonly observed fruit consumers in Menispermaceae. Birds species known disperse fruits and seeds include the eastern phoebe flycatchers (dispersing Cocculus DC.; Kessler 1993). Mammalian dispersal vectors include gorillas, lemurs, galagos (dispersing Cissampelos; Jacques 2009b), and white-faced monkeys (dispersing Cissampelos; Croat 1978). Forman (1986) points to humans as a recent and significant dispersal agent. Relatively little is known about menispermaceous fruit dispersal or seed predation within the family. Furthermore, the knowledge of endocarp adaptation is limited by the lack of information on the seed dispersal. Therefore, ecological studies and understanding of endocarp dispersal should provide new insights in the adaptive role of some endocarp features.
The molecular phylogeny of the three species C. orbiculatus, P. glaucus, and S. japonica, collected from Taiwan and preserved the herbarium (MO and HAST), has been reported (Ortiz et al. 2007). That study emphasized the importance of specimen exchanges among herbaria for different field studies. Some inconsistencies in our results could be addressed with an extensive sampling of fruits and genomic sequencing of the data. The endocarp characters we described can provide some phylogenetic information for a morphological phylogenetic analysis of this family.
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