I'm surprised to find the number of new described vascular plant species as low as 128.
Checking out Malvaceae at IPNI, new species are
Acropogon horarius (new discovery)
Andeimalva peruviana (new discovery)
Cola dorrii (segregate of Cola greenwayi)
Cola mamboana (new discovery)
Cola zemagoana (new discovery)
Eriolaena rulkensii (new discovery)
Hibiscus contortus (new discovery)
Quararibea nigrescens (new discovery)
Quararibea reflexipetala (new discovery)
Seringia botak (new discovery)
And looking in Google Scholar for species that haven't yet made their way to IPNI adds
Malvaceae represents about 1% of flowering plant diversity, so by extrapolation one would expect well over a thousand species. One of the papers sayings that the number of plant species described annually as new to science regularly exceeds 2,000.