Phylogeny of the ingoid clade (Caesalpinioideae, Fabaceae), based on nuclear and plastid data

Abstract

We investigated generic relationships in the ingoid clade (Fabaceae) (sensu Koenen & al. 2020a), with main focus on genera with a taxonomic history in Calliandra s.l. of the tribe Ingeae (i.e. Afrocalliandra, Calliandra s.s., Sanjappa, Thailentadopsis, Viguieranthus, Zapoteca), and three genera of the tribe Acacieae (i.e., Acacia, Acaciella, Senegalia). The nuclear ribosomal ETS and ITS, and the plastid matK, trnL-trnF and ycf1 DNA-regions were analysed for 246 representatives from 36 genera using maximum likelihood as implemented in IQ-tree. The results show an Ingeae–Acacia clade within the ingoid clade, resolved in three major clades. Clade 1 (Calliandra s.s. and Afrocalliandra) is sister to clades 2 and 3. Clade 2 comprises Faidherbia, Sanjappa, Thailentadopsis, Viguieranthus and Zapoteca. Clade 3 comprises the remaining genera of the Ingeae, plus Acacia. The ingoid genus Senegalia is excluded from the Ingeae–Acacia clade. Acaciella is sister to the remaining ingoid clade when nuclear ribosomal data is included in the analyses, but included in the Ingeae–Acacia clade based on plastid data. Acacia and perhaps also Acaciella are thus nested within Ingeae. Species traditionally referred to Calliandra (Calliandra s.l.) are resolved in two clades, and the “Calliandra-pod” has apparently evolved independently several times.

On Calliandra and Afrocalliandra (Fabaceae-Caesalpinioideae)

“…The two African species together were again resolved as sister to the neotropical members of Calliandra, just as in Souza et al (2013). The same result was obtained in the much more detailed study by Ferm et al (2021), focusing on "the ingoid clade" and based on both nuclear and plastid regions. In this analysis, the grouping with Calliandra and Afrocalliandra together was retrieved with strong support, and the African and neotropical clades were both strongly supported as well.…”

Studies of Asian ‘Calliandra' lead to expansion of Sanjappa (Fabaceae‐Caesalpinioideae)

“…sister to a clade with Viguieranthus glaber Villiers and Faidherbia albida. Ferm et al (2021), based on both nuclear and plastid markers and with a comprehensive sampling of the 'ingoid clade', retrieved a clade corresponding to the Zapoteca clade of Koenen et al (2020), with S. cynometroides strongly supported as sister to Thailentadopsis nitida and with F. albida as weakly supported sister to both these species together. Sister to this small Old World clade was, with strong support, a much larger clade with all sampled members of Viguieranthus, centered on Madagascar, as weakly supported sister to all sampled species of neotropical Zapoteca.…”