Croton droguetioides Kainul. & Radcl.

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 : 331-333

Croton droguetioides Kainul. & Radcl. -Sm., spec. nova ( Fig. 1B , 3-4 ).

Typus: M ADAGASCAR. Prov. Toamasina: Alaotra- Mangoro Region, Moramanga Distr., Andasibe , Berano , Ambatovy mine concession , 18°47’59”S 48°20’31”E, 1009 m, 22.III.2016, van Ee, Antilahimena, Kainulainen & Berry 2447 (holo-: MICH [ MICH1513195 ]!, iso-: MO!, P!, TAN!).

Croton droguetioides Kainul. & Radcl. -Sm. is similar to C. incisus Baill. but differs in its smaller leaves with serrate (vs. incised to lobed) leaf margin; distinct abaxial venation; apiculate (vs. acute) apex; and rounded to cordate (vs. cuneate) leaf base.

Shrubs or small trees, 0.8-7.0 m tall, to 6 cm diam., dichotomously branching, internodes sometimes contracted giving the appearance of whorled branches. Branches ± flattened on young growth and densely covered by villous white-gray stellate trichomes, gray, becoming terete and glabrous with age. Stipules linear, 1.1-1.6 mm. Leaves alternate, ± congested and whorled towards the branch tips and nodes. Petioles 3-15 mm, with a pair of stipitate glands at the junction of the blade and the petiole, usually on the abaxial side, the stipe 0.4-1.9 mm long, the glandular portion cupular. Leaf blades papyraceous, serrate, ovate to elliptic, 10-28 × 7-16 mm, apex apiculate, base rounded-cordate; adaxial surface sparsely stellate-pubescent or glabrescent, glossy, dark green when fresh and drying matte (brownish) green; with 3-6 pairs of brochidodromus, ± penninerved secondary veins; abaxial surface sparsely stellate-pubescent, mostly on the midrib; pale green, venation distinct and midrib prominent. Inflorescences racemose (often apically congested and umbel-like), to 20 mm long, axillary or terminal, with mostly staminate flowers, sometimes with a pistillate flower at the base; axes densely stellatepubescent, flattened; bracts linear to lanceolate, 1.7-2.2 mm. Staminate flowers with stellate-pubescent, subglobose buds 1.0- 1.2 mm diam., pedicels elongating from bud to anthesis, 2.0- 4.2 mm long; sepals 5, shortly connate at base, lobes broadly triangular-ovate, 0.9-1.2 × 0.8-1.0 mm, apex acute, abaxially stellate-pubescent, adaxially sparsely ciliate, margins densely ciliate, pale green; petals 5, white, narrowly obovate-spatulate, 1.4-1.7 × 0.5-0.6 mm, recurved at anthesis, abaxially papillate, adaxially ciliate, margins densely ciliate; disc glands 5, opposite the sepals, sessile, ellipsoid with an apical depression, c. 0.4 × 0.3 mm, yellow; stamens 13-16, white to pale yellow, filaments 1.3-1.8 mm long, ciliate, anthers elliptic, 0.3-0.5 mm long; receptacle pilose. Pistillate flowers with stellate-pubescent, subglobose buds c. 1.3 mm diam., pedicels 2.6-3.5 mm long; sepals 5, elliptic, spreading at anthesis, 2.0-3.8 × 0.7-1.5 mm, apex obtuse-acute, shortly connate at base, adaxially sparsely stellate-pubescent, abaxially stellate-pubescent, glossy, pale green, persistent in fruit; disc glands 5, opposite the sepals, sessile, c. 0.4 × 0.2 mm, pale yellow; glandular filaments (in petal position alternating with the sepals) 5, linear, c. 1.0 × 0.1 mm, ciliate, erect and appressed to the ovary; ovary globose, c. 1.5 mm diam., stellate, styles 3, 1.5-2.8 mm long, each bifurcating 2-4 times, spreading, recurved at the apices, adaxially glabrous but with whitish pilose trichomes at the base, abaxially stellate-pubescent, white, turning brown, persistent. Capsules 4.2-6.2 × 5.7-6.2 mm, smooth, pale brown, sparsely stellate-pubescent, exocarp not separating, endocarp woody, c. 0.2 mm thick; columella c. 4.5 mm long, cornute. Seeds not seen.

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]

Etymology. – The specific epithet refers to the similarity of the leaves of this species to those of species of Droguetia Gaudich. (Urticaceae) .

Vernacular name. – “Hazomby”.

Phenology. – We have seen flowering and fruiting specimens from January to May and from October. It is likely this species flowers more or less continuously throughout the year, although possibly less so in the drier months of the year.

Distribution, habitat and ecology. – Besides the Ambatovy-Analamay forests, C. droguetioides is also found in the Mantadia forests, in the Ambodimandresy forest (S of Route Nationale 2 near the Hotel Eulophiella), and at a more distant site north of Didy at Ambatoharanana (near Antsevabe); all are in the Alaotra-Mangoro Region of Toamasina Prov., at elevations of 975-1200 m ( Fig. 1B ). The species occurs in the understory of evergreen montane forests.

Notes. – Croton droguetioides can be readily distinguished from other small-leaved species of Malagasy Croton by its stems with pale, wooly and stellate trichomes, and its serrate leaves with a rounded to cordate base and distinct abaxial venation. In his unpublished manuscript on Malagasy Croton, Alan Radcliffe-Smith had selected Cours 4111 as the type collection for another proposed species (“ C. parietarioides ”), but we see no significant differences in it from the other specimens of C. droguetioides listed here.

Paratypi. – MADAGASCAR. Prov.Toamasina: Alaotra-Mangoro Region, Moramanga Distr., Ambatovy-Analamay forest , 18°48’56”S 48°18’21”E, 1086 m, 18.V.2011, Andriamiarinoro 211 ( MO, P, TAN); ibid. loc., 18°47’51”S 48°20’33”E, 1036 m, 11.X.2005, Antilahimena et al. 3953 ( MO, P, TAN); ibid. loc., 18°49’56”S 48°18’47”E, 1200 m, 12.X.2005, Antilahimena & Edmond 4017 ( G, MO, P, TAN); ibid. loc., 18°51’36”S 48°17’29”E, 1059 m, 21.X.2005, Antilahimena & Edmond 4086 ( MO, P, TAN); ibid. loc., 18°50’22”S 48°18’47”E, 1142 m, 24.I.2007, Antilahimena 5206 ( G, MO, P, TAN); ibid. loc., 18°51’04”S 48°17’23”E, 1059 m, 9.II.2007, Antilahimena 5253 ( MO, P, TAN); ibid. loc., 18°48’49”S 48°18’32”E, 1074 m, 5.III.2009, Antilahimena et al. 6998 ( MO, P, TAN); Andasibe, Ampangalatsara, Ambodimandresy forest , 18°59’07”S 48°25’53”E, 966 m, 17.III.2012, Antilahimena 8228 ( MICH, MO, P, TAN); Ambatovy, 18°50’22”S 48°18’15”E, 1087 m, 17.V.2010, Bernard et al. 1571 ( MO, P, TAN); Ambatoharanana près d’Antsevabe , [17°59’S 48°37’E], 1000 m, 6.III.1951, Cours 4111 ( K, P, TEF); Ambatovy, 18°50’20”S 48°18’44”E, 1174 m, 22.IX.2008, Miandrimanana et al. 345 ( MO, TAN); ibid. loc., 18°51’59’’S 48°18’15”E, 916 m, 12.VIII.2008, Rabevohitra et al. 129 ( TEF); Torotorofotsy, 18°53’S 48°21’E, 950 m, 24.II.1997, Rakotomalaza et al. 1170 ( MO, P); Ambatovy, 18°51’51”S 48°18’37”E, 1004 m, 10.II.2008, Rakotondrafara et al. 546 ( MO, P, TAN); ibid. loc., 1023 m, 14.II.2008, Rakotondrafara et al. 620 ( MO, P, TAN); Ambohibolakely, Analamay-Mantadia forest corridor , Amboasary forest , 18°47’11”S 48°23’00”E, 1019 m, 25.IV.2012, Rakotovao 5809 ( MO, P, TAN); Ambatovy, 18°51’50”S 48°18’35”E, 980 m, 11.II.2008, Randrianasolo et al. 643 ( MICH, MO, P, TAN); ibid. loc., 18°51’51”S 48°18’48”E, 980 m, 14.II.2008, Randrianasolo et al. 677 ( MO, P, TAN); Ambodimandresy forest , 18°59’19”S 48°25’59”E, 975 m, 16.III.2012, Razakamalala et al. 6747 ( MICH, MO, P, TAN); Ambatovy, 18°51’58”S 48°17’33”E, 1012 m, 17.I.2005, Razanatsoa et al. 76 ( MICH, MO, P, TAN); ibid. loc., 18°47’53”S 48°20’30”E, 1022 m, 22.III.2016, van Ee et al. 2443 ( MICH, 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. 3. – Croton droguetioides Kainul. & Radcl.-Sm. A. Habit and habitat in rainforest; B. Flowering branch with staminate flowers; C. Underside of branch showing the stipitate glands, the sparsely stellate-pubescent leaves and the villous petioles and stem; D. Inflorescence with staminate flowers and buds; E. Inflorescence with pistillate flower; F. Immature fruit.

Fig. 4. – Croton droguetioides Kainul. & Radcl.-Sm. A-B. Staminate flower; C. Staminate flower with stamens removed to show the nectaries; D-E. Pistillate flower; F. Pistillate flower with ovary removed to show the nectaries. Note the glandular filaments in the petal position. [A-C: van Ee et al. 2243; D-F: van Ee et al. 2247]