Croton sahafariensis Kainul. & P.E. Berry, 2017

Kainulainen, Kent, Ee, Benjamin van, Razafindraibe, Hanta & Berry, Paul E., 2017, A revision of the Adenophorus Group and other glandular-leaved species of Croton (Euphorbiaceae) from northern Madagascar and Mayotte, including three new species, Candollea 72 (2), pp. 371-402 : 395-396

Croton sahafariensis Kainul. & P.E. Berry , spec. nova ( Fig. 1G , 2D , 4 M-N, 11).

Typus: MADAGASCAR. Prov. Antsiranana: Diana Reg., Sahafary forest in the Saharaina river basin , road off of RN 6 to the E towards the “red tsingy” , 12°36’19”S 49°26’23”E, 250 m, 26.X.2009, van Ee et al. 1089 (holo-: MICH [ MICH1517187 ]!; iso-: P!, TAN) .

Croton sahafariensis Kainul. & P.E. Berry is similar to C. tsiampiensis Leandri , from which it differs in that the leaves are not markedly hirsute but instead have a whitish woolly pubescence on the abaxial side, and in having bracts which are usually extended well beyond the buds. In its opposite, woolly leaves and awn-like bracts C. sahafariensis may also be superficially similar to C. danguyanus Leandri , but that species lacks laminar glands and its pistillate flowers have an inflated, conduplicate calyx.

Shrubs 1.5-5 m tall, dichotomously branching, internodes sometimes so short as to give the appearance of whorled branches; in all parts covered in whitish or ferrugineous, stellate trichomes many of which have a bristly, porrect (to c. 2 mm) central radius. Branches flattened on new growth but becoming terete with age, pale grayish-green and hirsute with ferrugineous, stellate indument, soon turning a glabrous, matte gray to brown bark. Stipules 10-15 mm, lanceolate, entire, with marginal glands, caducous. Leaves deciduous, opposite. Petioles 1-10 cm, adaxially canaliculate, stellate-pubescent to markedly hirsute, usually with a pair of subsessile (stipe <1 mm), concave, discoid, yellow, glands (c. 0.5 in diam) by the base of the lamina. Leaf blades chartaceous, glandular denticulate, broadly ovate to subreniform, 2.4-15 × 2.3-11.5 cm, apex rounded, acute or shortly acuminate, base cordate; adaxial surface stellate-pubescent, pale green when fresh (turning orange in old leaves) and drying matte greenishbrown; venation evident, with 5-8 pairs of brochidodromus, ± penninerved secondary veins (the lowermost pairs congested and appearing palmate), and cross-venulate tertiary venation; abaxial surface light green, densely covered by ± woolly, whitish stellate-pubescent hairs with contrasting ferrugineous hairs scattered along the veins; venation prominent, with glands in some of the axils of the secondary veins ( Fig. 1G ). Inflorescences terminal, spike-like thryses to 8 cm long, with pistillate flowers more prevalent toward the base and staminate flowers towards the distal end, axes densely ferrugineous stellate-pubescent, flattened; bracts narrowly triangular to lanceolate, ± inflected, 3-7 mm long. Staminate flowers with stellate-pubescent, subglobose buds 1.6-2.5 mm in diam., pedicels elongating from bud to anthesis, 1.5-2 mm long; sepals 5, whitish, shortly connate at base, lobes broadly triangular-ovate, 1.5-2 × 1-1.3 mm, apex acute, inflexed at anthesis, abaxially ferrugineous stellate-pubescent, adaxially glabrous, margins ciliate; petals 5, white, elliptic-spatulate, c. 2.6 × 1.4 mm, recurved at anthesis, abaxially papillose and densely stellate-pubescent, adaxially glabrous, margins densely ciliate; disc glands 5, opposite the sepals, sessile, ellipsoidal with an apical depression, c. 0.4 × 0.5 mm, yellow; stamens 14-15, white, filaments 2-3.7 mm long, glabrous, anthers broadly elliptic, c. 0.6 × 0.5 mm; receptacle pilose. Pistillate flowers with stellatepubescent buds, c. 1.5 mm in diam., subsessile; sepals 5, triangular-ovate, spreading at anthesis, c. 2.5 × 1.2 mm, apex acute, shortly connate at base, abaxially and adaxially stellatepubescent, greenish yellow, persistent in fruit; petals absent or vestigial; disc glands 5, opposite the sepals, sessile, ellipsoidal, c. 0.3 × 0.6 mm, pale yellow; glandular filaments sometimes alternating with the disc glands, 0.2-0.4 mm long; ovary globose, 2-2.5 mm in diameter, densely hirsute by whitish to pale brown, long-rayed stellate trichomes, styles 3, 1.5- 2.0 mm long, each branch flattened and 2-3(-4) times bifurcate, spreading, recurved at the apices, abaxially stellate-pubescent, adaxially glabrous, greenish white, turning brown, persistent. Capsules globoid, c. 6.5 mm in diam., smooth, brown, covered with brown stellate trichomes ( Fig. 4M ), exocarp not separating, endocarp woody, c. 0.4 mm thick; columella 4.5-7 mm long, cornute, capitate. Seeds ± compressed-ellipsoid, 4-5.8 × 3-4.1 × 2.5 mm ( Fig. 4N ); testa glossy, verrucose, brown; caruncle narrowly reniform c. 0.6 × 1.4 mm.

Etymology. – The epithet refers to the Sahafary forest in Antsiranana Province, where the type was collected.

Phenology. – Only a few specimens are known, collected in flower in October-November and January-March, and in fruit in October, January, and March.

Distribution, habitat and ecology. – Croton sahafariensis occurs in deciduous forests in northern Antsiranana Province, on sandy or lateritic soils, at 150-300 m elevation ( Fig. 2D ).

Conservation assessment. – Croton sahafariensis is known only from small and fragmented populations at just four localities of threatened deciduous forests in Antsiranana Province (Ambohitsitondroina, Montagne des Français, Sahafary, and Tsaramborona). With an extent of occurrence <5,000 km 2 and an area of occupancy of <500 km 2 and with each of the four known localities representing separate threat locations, we assign this species as “Endangered” [EN B1ab(iii)+B2ab(iii)] according the IUCN Red List Categories and Criteria ( IUCN, 2012).

Notes. – This species can be recognized by its whitish, ± woolly pubescence on the abaxial side of the leaves with contrasting ferrugineous trichomes prevalent along the veins, and in its awn-like bracts that usually extend well beyond the buds ( Fig. 1G , 11 ). In these characteristics it may be superficially similar to C. danguyanus Leandri , however, that species has pistillate flowers with large, inflated, and conduplicate sepals, and the leaves lacks laminar glands; also, C. danguyanus is not part of the Adenophorus Group. Gautier & Chatelain 4876 is tentatively included here, but the leaves of this specimen are very young and small. The sterile specimen van Ee et al. 2363 from Montagne des Français probably also belong here. The leaves of this specimen are not woolly, but since it grew in the understory it is possible this represents phenotypical variation. There are currently no vernacular names recorded for this species.

Additional specimens examined. – MADAGASCAR. Prov. Antsiranana: SAVA Reg., Vohemar Distr., Daraina , Tsaramborona forest , 12°57’47”S 49°37’12”E, 150 m, 20.XI.2006, Gautier & Chatelain 4876 ( G, MICH, P) ; Daraina, Ambohitsitondroina forest , 13°07’44”S 49°27’29”E, 286 m, 6.I.2006, Nusbaumer & Ranirison 1862 ( G, MO) ; ibid loc., 13°07’56”S 49°28’21”E, 210 m, 12.I.2006, Ranirison & Nusbaumer 1077 ( G, K, P) ; Diana Reg., Antsiranana II Distr., Sadjoavato, Saharenana , Andranomadiro forest SW of Sahafary , 12°36’18”S 49°26’35”E, 300 m, 14.II.2005, Schatz et al. 4269 ( CNARP, G, MO, P, TAN) ; ibid loc., 12°36’20”S 49°26’22”E, 258 m, 2.III.2016, van Ee et al. 2312 ( MICH, TAN) ; ibid loc., van Ee et al. 2313 ( MICH, TAN) ; ibid loc., van Ee et al. 2314 ( MICH, TAN) ; Montagne des Français , 12°19’25”S 49°20’10”E, 235 m, 5.III.2016, van Ee et al. 2363 ( MICH, TAN) .

Figures

Fig. 1. Abaxial side of leaves showing laminar glands and pubescence A. Croton nudatus Baill.; B. Croton stanneus Baill.; C. Croton adenophorus Baill.; D. Croton bathianus Leandri; E. Croton loucoubensis Baill.; F. Croton orangeae Kainul. & Berry; G. Croton sahafariensis Kainul. & Berry; H. Croton scoriarum Leandri; I. Croton tsiampiensis Leandri. [A: van Ee et al. 2340; B: van Ee et al. 2160; C: van Ee et al. 1135; D: van Ee et al. 1138; E: Ammann et al. 378; F: van Ee et al. 2353; G: van Ee et al. 1089; H: van Ee et al. 2329; I: Nusbaumer LN 902]

Fig. 2. Distribution maps. A. Croton nudatus Baill. (white), C. stanneus Baill. (yellow); B. Croton adenophorus Baill. (green) and C. tsiampiensis Leandri (white); C. Croton bathianus Leandri (light blue), C. loucoubensis Baill. (yellow), and Croton scoriarum Leandri (red); D. Croton orangeae Kainul. & Berry (red) and C. sahafariensis Kainul. & Berry (yellow); E. Croton mayottae P.E. Berry & Kainul. [Google Earth Image © 2017 DigitalGlobe. Reproduced per attribution guidelines]

Fig. 4. Capsules (A, C, E, G, I, K, M, O); Seeds (B, D, F, H, J, L, N, P). A-B. Croton nudatus Baill.; C-D. Croton stanneus Baill.; E-F. Croton adenophorus Baill.; G-H. Croton bathianus Baill.; I-J. Croton loucoubensis Baill.; K-L. Croton orangeae Kainul. & P.E. Berry; M-N. Croton sahafariensis Kainul. & P.E. Berry; O-P. Croton tsiampiensis Leandri. [A: Randrianaivo et al. 1424; B: Gautier & Chatelain 4898; C: Gillespie 10802; D: Nusbaumer LN 906; E: van Ee et al. 1165; F: van Ee et al. 2294; G: van Ee et al. 2406; H: van Ee et al.1138; I: Nusbaumer 2536; J: Bernard et al. 1192; K-L: Razafitsalama et al. 692; M-N: van Ee et al. 2314; O-P: Nusbaumer 902]

Fig. 11. Croton sahafariensis Kainul. & Berry A. Branch with young inflorescences. Note the awn-like bracts; B. Underside of the leaves showing whitish woolly pubescence with contrasting ferrugineous hairs along the veins. Note laminar glands (arrow); C-D. Inflorescences with staminate and pistillate flowers; E. Young fruit.