Croton ferricretus Kainul., B.W. van Ee & P.E. Berry, 2016

Kainulainen, Kent, Ee, Benjamin van, Antilahimena, Patrice, Razafindraibe, Hanta & Berry, Paul E., 2016, New species and species reports of Croton L. (Euphorbiaceae) from the eastern forest corridor of Madagascar, Candollea 71 (2), pp. 327-356 : 337-338

Croton ferricretus Kainul., B.W. van Ee & P.E. Berry , spec. nova ( Fig. 1A , 5 H-M, 7A-B, 8).

Typus: MADAGASCAR. Prov. Toamasina: Alaotra- Mangoro Region, Moramanga Distr., Andasibe, Berano , Ambatovy mine concession , on “cuirasse” between the workers houses and the Ambatovy supply road, within sight of the Ambatovy office building, 18°51’02”S 48°18’29”E, 1142 m, 21.III.2016, van Ee, Antilahimena, Kainulainen & Berry 2436 (holo- MICH [ MICH1513194 ]!; iso-: G!, K!, MAPR!, MO!, P!, TAN!).

Croton ferricretus Kainul., B.W. van Ee & P.E. Berry is similar to C. antanosiensis Leandri in its medium-sized, lepidote leaves and elongate inflorescences, but differs from it in the more ferrugineous indumentum (vs. silvery), shorter petioles, and obloid (vs. globoid) capsules.

Shrubs 0.4-4 m tall, dichotomously branching, internodes sometimes contracted giving the appearance of whorled branches. Branches ± flattened on new growth and densely ferrugineous-lepidote, brown or gray, becoming terete and glabrous with age. Stipules linear-triangular, 0.5-1 mm. Leaves alternate along stem, subopposite or whorled at apex. Petioles 3-17(-28) mm, adaxially canaliculate, without any apparent glands. Leaf blades subcoriaceous, entire, elliptic, 18-85 × 9-28 mm, apex acute to shortly acuminate (rarely obtuse), base cuneate; adaxial surface glabrous, glossy, dark green when fresh (turning orange in old leaves) and drying gray-green; venation impressed, obscure, with 10-20 pairs of brochidodromus, ± penninerved secondary veins; abaxial surface densely silverylepidote and ferrugineous-punctate, the ferrugineous scales scattered among silvery ones, but more prevalent on the leaf veins; midrib prominent, ferrugineous-lepidote. Inflorescences racemose, 20-85 mm long, axillary or terminal, with mostly staminate flowers, usually with 1-2(-5) pistillate flowers at the base; axes densely ferrugineous-lepidote, flattened; bracts linear-lanceolate, 1-3 mm long. Staminate flowers with ferrugineous-lepidote, subglobose buds 1.5-2.5 mm in diam., pedicels elongating from bud to anthesis, 2-5 mm long; sepals 5, firm, connate about halfway from the base, lobes broadly triangular to ovate, 1.0-1.4 × 0.8-1.7 mm, apex acute, inflexed at anthesis, abaxially ferrugineous-lepidote, adaxially glabrous, pale green; petals 5, white, narrowly obovate-spatulate, 1.8-2.5 × 0.5-1.1 mm, recurved at anthesis, abaxially lepidote, adaxially ciliate, margins densely ciliate; disc glands/nectaries 5, opposite the sepals, sessile, ellipsoid with an apical depression, 0.6-0.8 × 0.5-0.7 mm, yellow; stamens 14-19, white to pale yellow, filaments 1-2 mm long, ciliate, anthers elliptic, 0.5- 0.7 mm long; receptacle pilose. Pistillate flowers with ferrugineous-lepidote, elliptic buds 2.8-3.0 × 1.7-2.5 mm, pedicels 1-8 mm long; sepals 5, firm, narrowly triangular, ascending at anthesis, 1.8-5.3 × 0.5-1.3 mm, apex acute, shortly connate at base, abaxially ferrugineous-lepidote, adaxially glabrous, pale green, persistent in fruit; petals absent/reduced; disc glands/ nectaries 5, opposite the sepals, sessile, pentagonal, 0.8-1.0 × 0.6-0.8 mm, yellow; ovary obloid, 2.0- 2.5 mm diam., lepidote, styles 3, c. 3 mm long, each bifurcating twice (or ultimately thrice), spreading, recurved at the apices, abaxially ferrugineous-lepidote, adaxially glabrous but with yellowish pilose trichomes at the base, white, turning brown, persistent. Capsules 4.5-9.0 × 3.5-6.0 mm, smooth, gray-green, lepidote, exocarp not separating, endocarp woody, c. 0.2 mm thick; columella 4-6 mm long, cornute, capitate. Seeds ± compressed-ellipsoid, c. 5 × 3 × 2 mm; testa glossy, rugulose, punctate, dark brown; caruncle reniform c. 1.3 × 0.5 mm.

Etymology. – The specific epithet refers to the ultramafic ferricrete soils to which this species is restricted.

Vernacular names. – “Fotsiavadika”, “Lazalaza”.

Phenology. – Flowering and fruiting specimens have been collected from May through March, indicating that Croton ferricretus is quite aseasonal in its phenology.

Distribution, habitat and ecology. – Croton ferricretus is so far only known from the Ambatovy-Analamay forest in Madagascar’s Moramanga Distr., occurring at 1000-1150 m altitude on ultramafic ferricrete soils ( Fig. 1A , 8A ). It is a common and sometimes dominant component of the scrublands found on the most extreme rock-like crusts, and it also occurs in adjacent evergreen forests with better-developed soils. When growing on bare ferricrete (“cuirasse”), C. ferricretus does not occur with other species of Croton , but in forested areas it can be found growing alongside C. lichenisilvae Leandri , C. macrobuxus Baill. , C. nitidulus Baker , C. submetallicus Baill. , or C. droguetioides .

Notes. – Croton ferricretus was recognized in the inventory of the Ambatovy-Analamay forest by PHILLIPSON et al. (2010) under the working name “ Croton lepidotoides ” (ined. by the late Radcliffe-Smith), and considered a species of concern (SOC2, i.e., found only in the area of the mining footprint and the surrounding conservation zone). This is a very distinctive species among Malagasy Crotons that have small- to medium-small leaves with coppery-lepidote indumentum ( Fig. 8 B-C). Other species that have these characteristics tend to have glomerulate inflorescences in the leaf axils, such as C. jennyanus Gris ex Baill. and C. hypochalibaeus Baill. , rather than racemose inflorescences ( Fig. 8 D-F). It resembles C. antanosiensis Leandri from southeastern Madagascar, but differs in its much more coppery-lepidote indumentum, shorter petioles, and more obloid capsules ( Fig. 7A ).

Since this is a locally common species that is capable of growing on bare, ferricrete substrates, we believe that it may be an excellent candidate for revegetation efforts once the mining operations at Ambatovy-Analamay have ceased. Its shrubby habit would enable it to reproduce more quickly than tree species, and it could help stabilize slopes in previously mined areas.

Paratypi. – MADAGASCAR. Prov. Toamasina: Alaotra-Mangoro Region, Moramanga distr., Ambatovy-Analamay forest , 18°50’47”S 48°18’28”E, 1137 m, 9.II.2005, Antilahimena et al. 3323 ( G, K, MO, P, TAN); ibid.loc., 18°51’27”S 48°19’07”E, 1113 m, 30.IX.2005, Antilahimena & Edmond 3862 ( MICH, MO, P, TAN); ibid.loc., Antilahimena & Edmond 3863 ( MICH, MO, P, TAN); ibid.loc., 18°48’28”S 48°20’11”E, 1049 m, 2.XII.2005, Antilahimena et al. 4324 ( G, MO, P, TAN); ibid.loc., 18°48’29”S 48°20’21”E, 1104 m, 21.XII.2005, Antilahimena 4513 ( G, K, MO, P, TAN); ibid.loc., 18°51’01”S 48°18’30”E, 1119 m, 6.III.2008, Antilahimena et al. 6140 ( MICH, MO, P, TAN), 18°51’01”S 48°18’30”E, 1119 m, 6.V.2008, Antilahimena et al. 6144 ( MICH, MO, P, TAN); ibid.loc., 18°51’11”S 48°19’05”E, 1095 m, 27.X.2008, Antilahimena et al. 6765 ( MO, TAN); ibid.loc., 18°51’00”S 48°18’29”E, 1114 m, 12.XI.2009, Antilahimena & Edmond 7175 ( MICH, MO, P, TAN); ibid. loc., 18°48’34”S 48°19’08”E, 1080 m, 5.X.2007, Bernard & Phillipson 596 ( MICH, MO, P, TAN); ibid.loc., 18°48’32”S 48°20’42”E, 11.X.2007, Bernard & Phillipson 619 ( MICH, MO, P, TAN); ibid.loc., 18°51’14”S 48°18’56”E, 1114 m, 18.I.2010, Bernard et al. 1532 ( MO, P, TAN); ibid.loc., 18°48’12”S 48°21’56”E, 995 m, 3.VI.2007, Miandrimanana et al. 201 ( MO, P, TAN); 22.II.1965, Peltier & Peltier 5169 ( P); ibid.loc., Peltier & Peltier 5994 ( P); 18°48’31”S 48°20’39”E, 1115 m, 6.X.2007, Phillipson et al. 6034 ( MICH, MO, TAN); ibid.loc., 18°51’08”S 48°18’40”E, 1121 m, 30.I.1997, Rakotomalaza et al. 1024 ( MO, P, TAN); ibid.loc., 18°48’28”S 48°20’04”E, 1083 m, 4.IV.2005, Rakotovao & Edmond 1801 ( MO, TAN); 18°48’22”S 48°20’13”E, 1075 m, 3.VIII.2005, Rakotovao et al. 1961 ( MICH, MO, P, TAN); 18°48’29”S 48°19’17”E, 1122 m, 16.I.2005, Ranaivojaona et al. 1101 ( MICH, MO, P, TAN); ibid.loc., 18°50’04”S 48°17’46”E, 1107 m, 15.II.2005, Razanatsoa et al. 113 ( MICH, MO, P, TAN); ibid.loc., 18°51’06”S 48°18’40”E, 1114 m, 18.II.2005, Razanatsoa et al. 187 ( G, MO, P, TAN); ibid.loc., 18°51’24”S 48°19’02”E, 1114 m, 26.IX.2005, Razanatsoa et al. 401 ( G, MO, P, TAN); 18°49’20”S 48°19’40”E, 1132 m, 20.X.2005, Razanatsoa & Razafindasy 548 ( MO, P, TAN); ibid.loc., 4.III.1987, Service Forestier 31265 ( TEF); ibid.loc., 18°48’55”S 48°19’28”E, 1114 m, 21.III.2016, van Ee et al. 2437C ( MICH, MO, P, TAN); ibid.loc., van Ee et al. 2438 ( MICH, MO, P, TAN); ibid.loc., 18°48’28”S 48°20’11”E, 1050 m, 22.III.2016, v an Ee et al. 2454 ( MICH, MO, P, TAN); ibid.loc., van Ee et al. 2455 ( MICH, MO, P, TAN).

Figures

Fig. 1. – Distribution maps. The grey squares or white arrow on the inset maps of Madagascar show the location of the area depicted. A. Croton ferricretus Kainul., B.W. van Ee & P.E. Berry (red); B. Distribution of Croton droguetioides Kainul. & Radcl.-Sm. (turquoise) (Cours 4111 not shown), C. enigmaticus P.E. Berry & B.W. van Ee (light green) (Ralimanana et al. 1402 not shown), C. indrisilvae Kainul., B.W. van Ee & P.E. Berry (yellow), and C. plurispicatus P.E. Berry, Kainul. & B.W. van Ee (light purple); C. Croton ankeranae Kainul. (yellow), C. radiatus P.E. Berry & Kainul. (red), and Croton lasiopyrus Baill. (white). The collection in gray represents presumed hybrids between C. lasiopyrus and C. enigmaticus (van Ee et al. 2215 and 2216); D. Croton hypochalibaeus Baill. in Madagascar. [Google Earth Image © 2016 DigitalGlobe.Reproduced per attribution guidelines]

Fig. 5. – Croton enigmaticus P.E. Berry & B.W. van Ee (A-G) and C. ferricretus Kainul., B.W. van Ee & P.E. Berry (H-M). A. Side view of staminate flower; B. Top view of staminate flower; C. Top view of staminate flower with the stamens removed to show the nectaries; D. Side view of pistillate flower with one of the sepals removed; E. Top view of pistillate flower with one of the sepals removed; F. Top view of pistillate with the ovary removed to show the five nectaries; G. Close-up of the base of a pistillate flower with the ovary and sepals removed, showing the five glandular filaments in the position of the petals (alternating with the sepals); H. Side view of staminate flower; I. Top view of staminate flower; J. Top view of staminate flower with stamens removed to show the five nectaries; K. Side view of pistillate flower. Note basally connate sepals and parallel sides; L. Top view of pistillate flower, showing the patent, bifurcating stigmas; M. Top view of pistillate flower with ovary removed to show the five nectaries. [A-G: van Ee et al. 2214; H-M: van Ee et al. 2436]

Fig. 8. – Croton ferricretus Kainul., B.W. van Ee & P.E. Berry. A. Typical habitat on ultramafic crust, with C. ferricretus dominating the understory; B. Habit; C. Underside of branch showing the silvery-lepidote and ferrugineous-punctate leaves; D. Inflorescence with staminate flowers and buds; E. Inflorescence with pistillate flower and bud; F. Infructescence with immature fruits; G. Mature capsule. [Photos: C-D, F: P.Berry; A-B, E, G: K. Kainulainen]

Fig. 7. – Croton ferricretus Kainul., B.W. van Ee & P.E. Berry (A-B), C. plurispicatus P.E. Berry, Kainul. & B.W. van Ee (C-D), C. hypochalibaeus Baill. (E-F), C. indrisilvae Kainul., B.W. van Ee & P.E. Berry (G-H), and C. enigmaticus P.E. Berry & B.W. van Ee (I-J). A, C, E, G, I. Capsule; B, D, F, H, J. Seed. [A-B: van Ee et al. 2436; C: van Ee et al. 2198; D: Ranaivojaona & Razanatsima 1173; E-F: van Ee et al. 2472; G-H: van Ee et al. 2176; I-J: van Ee et al.2214]