Croton nobilis Baill., Adansonia 1: 148. 1861, as 'nobile'

Berry, Paul E., Kainulainen, Kent & Ee, Benjamin W. van, 2017, A Nomenclator of Croton (Euphorbiaceae) in Madagascar, the Comoros Archipelago, and the Mascarene Islands, PhytoKeys 90, pp. 1-87 : 52

100. Croton nobilis Baill., Adansonia 1: 148. 1861, as 'nobile'

Oxydectes nobilis (Baill.) Kuntze, Revis. Gen. Pl. 2: 612. 1891. Type. Based on Croton nobilis Baill.

Type.

Madagascar. sin. loc.,s.d., L.M.A. Dupetit -Thouars s.n. (lectotype, designated here: P [P00133651]!; isolectotypes: P [P00133652]!, P [P00312353]!). Madagascar. Prov. Toliara: Anosy Region, southern slopes of Col de Maningotry, road to Ranomafana , 150 m, 16 Feb 2009, B. van Ee, P.E. Berry, B.L. Dorsey & H. Razanatsoa 938 (epitype, designated here: MICH [MICH1514784]!; additional duplicates: MO, P, TAN) .

Habit and distribution.

Trees; submontane moist forests of southeastern Madagascar (Toliara).

Notes.

The existing syntypes of Croton nobilis at P are all large-leaved (most around 18 × 7 cm), sterile branches. They are consistent with oversized sucker shoots that can sometimes be found on basal growth or regrowth of cut trees. The leaves on these specimens also resemble sucker leaves of C. chrysodaphne , which comes from eastern coastal Madagascar. However, Baillon (1861) clearly stated in the protologue that the staminate flowers of C. nobilis have five petals (the normal state in Croton ), whereas C. chyrsodaphne usually has ten ( Berry et al. 2011). Also, the pistillate sepals of C. chrysodaphne are described by Baillon (1861) as being oblong and entire, whereas those of C. nobilis are broad, squat, and reduplicate (Berry, pers. obs.). The lectotype chosen here contains a packet labeled “Flores,” with only a small fragment of an inflorescence with an irregularly flattened and straight rachis, but lacking any recognizeable floral parts that can be reconstructed. The inflorescences of C. chrysodaphne tend to be more slender, subterete, and curved, and this fragment does not fit that profile. Finally, Du Petit-Thouars spent six months in the Fort Dauphin area between 1792 and 1793 ( Dorr 1997), so this would be consistent with the limited localities where C. nobilis occurs to the northwest of Fort Dauphin. We therefore conclude that the Dupetit -Thouars collections are consistent with the tree species that has subsequently been collected in moist, mid-elevation forests in the area that is now part of Andohahela National Park, named C. nobilis . To stabilize better this concept of C. nobilis , we designate here a modern epitype that has also been photographed in situ (viz., Fig. 1B ) and sequenced for molecular phylogenetic studies ( Haber et al. 2017).

Figures

Figure 1. Diversity of flowers in coppery-lepidote tree species of Croton from Madagascar that are vegetatively very similar. A Croton argyrodaphne, with leaves that are similar to those of several other species B Part of an inflorescence of Croton nobilis showing pistillate flower (below) with thick, reduplicate sepals and no petals, and staminate flower (above) with an intermediate number of stamens (ca. 18) C Staminate flower of C. chrysodaphne, with numerous (ca. 40) stamens and the unusual feature of ten (vs. normally five) petals D Pistillate flower of C. chrysodaphne, with patent, slender bifurcating styles and no petals E Staminate flowers of C. argyrodaphne, with only 11 stamens F Pistillate flower of C. argyrodaphne, with a stylar column topped by tightly bunched, short stigmas and also with recurved petals between the sepals (typically the pistillate flowers of this species are apetalous) G Base of an inflorescence of C. multicostatus showing three open pistillate flowers at the base (with well-developed, ligulate petals) and several open staminate flowers showing a low stamen number of 10 or 11. Photos by P. Berry.