Monanthotaxis atopostema P.H.Hoekstra, 2016

Hoekstra, Paul H., Wieringa, Jan J. & Chatrou, Lars W., 2016, A nonet of novel species of Monanthotaxis (Annonaceae) from around Africa, PhytoKeys 69, pp. 71-103 : 72-73

Monanthotaxis atopostema P.H.Hoekstra nom. nov.

Monanthotaxis atopostema Replacement name for: Atopostema angustifolia Boutique, Bull. Jard. Bot. Brux. 21:121 (1951) (non Monanthotaxis angustifolia (Exell) Verdc., Kew Bull. 25: 21, 1971).

Popowia klainei Engl. var. angustifolia (Boutique) Le Thomas, Adansonia, sér. 2, 3: 291 (1963).

Monanthotaxis klainei (Engl.) Verdc. var. angustifolia (Boutique) Verdc., Kew Bull. 25: 21 (1971).

Note.

This species was described by Boutique (1951) based on the different leaf shape compared to Monanthotaxis klainei (Engl.) Verdc. The lack of other distinguishing features with Monanthotaxis klainei was the reason of Le Thomas (1963) and Verdcourt (1971) to treat it as a variety of Monanthotaxis klainei . However, they had only the availability of one flowering specimen. Now with an increased number of specimens available including fruiting material, we warrant it necessary to appraise this taxon again at species level. This species differs from Monanthotaxis klainei as mentioned by Boutique in the leaf shape, i.e. oblong to elliptic vs obovate in Monanthotaxis klainei , the rounded leaf base vs subcordate, the generally lower number of secondary veins (6-8 vs 7-12 in Monanthotaxis klainei ) and it differs in the number of ovules per carpel (up to 6 vs 1 or 2 in Monanthotaxis klainei ) and therefore also in the number of seeds per fruit. This species occurs sympatrically with Monanthotaxis klainei var. klainei , but differs from that species in having shorter pedicels (up to 12 mm in fruiting material vs 15-24 mm in fruiting material of Monanthotaxis klainei var. klainei ). Actually, this species is much more similar in general aspects with Monanthotaxis aquila P.H.Hoekstra and Monanthotaxis couvreurii P.H.Hoekstra which are newly described in this article. It can be distinguished from those two species by the characteristics mentioned in Table 1 . The epithet " atopostema " refers to the genus Atopostema Boutique in which it first was described. It is used as a noun.