Croton hypochalibaeus Baill.
Creators: name: Kainulainen, Kent
name: Ee, Benjamin van
name: Antilahimena, Patrice
name: Razafindraibe, Hanta
name: Berry, Paul E.
Publisher: name: Zenodo
Year: 2016
Subjects: Biodiversity
Taxonomy
Plantae
Tracheophyta
Magnoliopsida
Malpighiales
Euphorbiaceae
Croton
Croton hypochalibaeus

description: Croton hypochalibaeus Baill. in Bull. Mens. Soc. Linn. Paris 2: 262. 1890 (Fig. 1D, 12 G-L, 13).
Lectotypus (designated here): MADAGASCAR: sine loc., s.d., Baron 5635 (K [K001040371]!; isolecto-: P [P00133213, P00133661]!).
Shrubs or trees to 5 m tall, dichotomously branching, with internodes 2-14 cm long separating tight clusters of leaves at the nodes, giving the appearance of whorled branches. Branches ± flattened on new growth and densely brown-lepidote, brown or gray, becoming terete and glabrous with age. Stipules awnshaped, 0.9-1.5 mm. Leaves congested and ± whorled at apex and nodes. Petioles 1-15 mm, adaxially canaliculate, without any apparent glands. Leaf blades papyraceous, entire or with shallow irregular undulations, narrowly elliptic to obovate, (7-)21-77(-145) × (5-)9-31(-45) mm, apex acute to long acuminate (rarely obtuse), base attenuate to cuneate; adaxial surface silvery-lepidote (young leaves appear silvery), glossy, (dark) green when fresh (turning orange in old leaves) and drying matte gray-green; venation impressed, not prominent, with 4-11 pairs of brochidodromus, ± penninerved secondary veins; abaxial surface densely silvery-lepidote and brown punctulate, the brown scales ± evenly scattered among silvery white scales; venation indistinct except for the brown-lepidote midrib. Inflorescences shortly racemose to fasciculate, 2-8(-10) mm long, axillary or terminal, with mostly staminate flowers, sometimes with 1-2 pistillate flowers at the base; axes densely brown-lepidote, flattened; bracts linear to spatulate, to 6.5 × 1.2 mm. Staminate flowers with brown-lepidote, subglobose buds 1.0- 1.4 mm diam., pedicels elongating from bud to anthesis, 1-4 mm long; sepals 5, firm, shortly connate at base, lobes broadly triangular to ovate, 1.0-1.6 × 0.9-1.5 mm, apex acute to rounded, inflexed at anthesis, abaxially brownlepidote, adaxially glabrous, white; petals 5, white, elliptic to spatulate, 2.0-2.9 × 0.7-1.1 mm, recurved at anthesis, abaxially papillate, adaxially glabrous, margins densely ciliate; disc glands/nectaries 5, opposite the sepals, sessile, triangular with an apical depression, 0.4-0.5 × 0.3-0.5 mm, yellow; stamens 10-18, white to pale yellow, filaments 1.1-3.2 mm long, ciliate, anthers elliptic, 0.5-0.9 mm long; receptacle pilose. Pistillate flowers with brown-lepidote buds 1.5-1.8 mm diam., pedicels 1-3(-5) mm long; sepals 5, firm, broadly elliptic, spreading at anthesis, 1.6-2.4(-5.5) × 0.9-2.2(-2.7) mm, apex acute and inflexed, shortly connate at base, abaxially lepidote, adaxially ± lepidote and ciliate towards apex, greenish white-green, persistent in fruit; petals usually absent/reduced; disc glands/ nectaries 5, opposite the sepals, sessile, ellipsoidal with a short apex, 0.2-0.6 × 0.6-1.0 mm, pale yellow; glandular filaments (in petal position alternating with the nectary lobes) 5, 0.3- 0.8 mm long; ovary subglobose, c. 2.0 mm diam., lepidote, styles 3, 2.3-5.0 mm long, flattened, each bifurcating 3-4 times, often with the first bifurcation congested and fused to appear 4-furcate, spreading, recurved at the apices, abaxially lepidote, adaxially glabrous (but appearing lepidote in some specimens where the edges of the style branches are rolled up), white, turning brown, persistent. Capsules 4.6-6.7 × c. 4.3 mm (Fig. 7E), smooth, (pale) brown, lepidote, exocarp not separating, endocarp woody, c. 0.2 mm thick; columella 3.8-5.2 mm long, cornute, capitate. Seeds ± compressed-ellipsoid (Fig. 7F), c. 4.0 × 3.0 × 2.5 mm; testa glossy, punctate, brown; caruncle reniform c. 0.7 × 0.5 mm.
Etymology. – The epithet refers to the steel-colored lepidote indumentum on the underside of the leaves.
Phenology. – Both flowering and fruiting specimens have been collected from October to April (we have not seen any specimens collected between May and September), indicating that C. hypochalibaeus is aseasonal in its phenology.
Distribution, habitat and ecology. – Croton hypochalibaeus is mostly restricted to the eastern montane forests and the central highland plateau of Madagascar (“tampoketsa”) at elevations of 800-1600 m, but also occurs as low as 675 m at Ankerana. Most collections are from Toamasina Prov. (Ambatovy, Andasibe, Ankerana, and Zahamena), but it has also been collected in Ambohitantely and Sohisika (Antananarivo Prov.) and as far south as Ivohibe in Fianarantsoa Prov. and Isalo National Park in Toliara Prov. Some doubtful specimens from Antsiranana Prov. are also mapped (see Fig. 1D). It typically grows in primary forest understory but it also occurs along the edges of forests or in secondary woody vegetation.
Vernacular names. – “Lazalaza madinidravina”, “Lazalaza madinika”, “Tsiavalika”.
Notes. – The two specimens of Baron 5635 at P are sparser fragments of the more complete specimen at K. Since LEANDRI (1939) treated C. hypochalibaeus as a synonym of C. noronhae, the name has not been applied to contemporary Malagasy Crotons, but the two species differ both morphologically and ecologically. Croton noronhae is restricted to littoral, sandy-soil forests along the eastern coast of Madagascar and has dark reddish velvety shoots compared to smooth, brown-lepidote shoots in C. hypochalibaeus; it also has evident acropetiolar glands, which are lacking in C. hypochalibaeus. In the Ambatovy checklist of PHILLIPSON et al. (2010, Table 1), some of the specimens of C. hypochalibaeus listed below were determined either as C. jennyanus, C. noronhae, C. sp. nov. B aff. jennyanus, or the nom. nud. “ Croton alceicornu Radcl. -Sm.” These all form part of a complex of small-leaved Crotons in Madagascar that have silvery- or coppery-lepidote leaf undersides and very condensed inflorescences. Just as with the group of large-leaved silvery Croton species that were first highlighted by LEANDRI (1972), it takes detailed field experience and careful examination of flowering and fruiting material to be able to successfully distinguish among the component species. The true C. jennyanus is restricted to northern Antsiranana Prov. at low altitudes and shows less evidence of sylleptic branching than C. hypochalibaeus. Also, its leaves have an acute to mucronate apex and a cuneate to rounded base (vs. an acute to long-acuminate apex and attenuate to cuneate base in C. hypochalibaeus), and the leaves usually dries a nitid green above (vs. a matte gray-green in C. hypochalibaeus), and are ferrugineous-punctate and (silvery) glossy below (vs. brown-punctulate and matte [greenish- or grayish-] white in C. hypochalibaeus). Specimens that were previously identified as “ Croton alceicornu Radcl. -Sm., ined.” have smaller, rounder leaves than typical C. hypochalibaeus specimens, but we could find no consistent differences in floral characters between them. Still, closer study in the field and examination of better reproductive material may in the future justify recognition of a separate taxon for this entity.
There are some geographically outlying specimens that are referred here with some reservation; they are represented on the distribution map (Fig. 1D) by the four dots at the northern tip of the island. Ranirison 631 from the Ampondrabe forest in Daraina (12°57’29’’S 49°41’50’’E, 580 m, 11.IV.2004, G, P) seems to be a more reduced version of this species in terms of leaf size and compact growth. However, the label alludes to the sylleptic branching pattern that is typical of this species, and the habitat is described as a subhumid, high altitude forest. Similar specimens collected in the Antsahabe forest near Daraina, are Nusbaumer 986, (13°13’02’’S 49°33’11’’E, 950 m, 15.I.2004, G, P) and Rakotondrafara et al. 358 (13°13’06’’S 49°33’02’’E, 790 m, 1.XI.2005, MO, P). On the northwestern side of the island, Harder et al. 1590, from Montagne d’Ambre (12°30’48”S 49°10’59”E, 990 m, 15.IV.1993, MO, P), is also a close match to this species, but since it is the only collection we have seen from this isolated massif, we would like to see further material to confirm its presence there. Finally, Burivalova 186, from Andrafiamena, Anjahankely, (12°54’60”S 49°21’47”E, 726 m, 7.I.2010, G, P), may also belong here, but again, it would be helpful to see additional specimens to confirm its presence in this part of Antsiranana Prov.
Additional specimens examined. – MADAGASCAR. Prov. Antananarivo: Analamanga Region, Ankazobe Distr., Ankazobe, Firarazana, Ankafobe forest, 18°06’10”S 47°11’12”E, 1492 m, Andrianjafy 1910 (MICH, MO, P, TAN); ibid. loc., Andrianjafy 1914 (MO, P, TAN); ibid. loc., XI.1955, Bosser 8596 (P); Mandraka, route de Tamatave, 2.XI.1972, Debray 1848 (P); Ankazobe, 29.IV.1943, Decary 19358 (K, P); 25 km NNE Ankazobe, 18°06’S 47°11’E, c. 1500 m, 5.XII.1990, Gillespie 4106 (K, MO); Ambohitantely forest, c. 1600 m, X.1933, Humbert 11111 (G, P); Manjato forest, 18°06’19”S 47°14’49”E, 13.IV.2007, Rakotoarivelo 62 (MO, P); Ankafobe forest, 18°06’21”S 47°11’14”E, 1464 m, 5.IV.2013, Randrianaivo et al. 2243 (MO, P); ibid. loc., 18°06’11”S 47°11’10”E, 14.XII.1999, Razafindrakoto et al. 30 (K, MICH, MO, P, TAN); Massif de Manohilahy, Anjozorobe, 22.VIII.1952, Service Forestier 5660 (P); Sohisika Nature Reserve, 18°06’08”S 47°11’09”E, 1530 m, 20.X.2009, van Ee et al. 1011 (MICH, TAN); below village of Andranofeno Sud, 18°05’02”S 47°10’49”E, 1430 m, 24.II.2016, van Ee et al. 2261 (MICH, MO, P, TAN). Prov. Fianarantsoa: [Ihorombe Region], Ifandana, 7.IX.1926, Decary 5246 (K, P); Ivohibe Distr., Réserve spéciale du Pic d’Ivohibe, Marovitsika forest, 22°28’49”S 46°56’49”E, 930 m, 18.X.2000, Hoffmann et al. 237 (G, K, P); [Amoron’i Mania Region], Faliarivo à l’W d’Ambositra, 1600 m, 15.I.1955, Humbert & Capuron 28034 (K, P); [Ihorombe Region, Ihosy Distr.] Isalo, Canyon des Singes, 15.IV.67, Jacquemin H280J (K); ibid. loc., 22°29’S 45°23’E, c. 800 m, 4.XI.1994, Lewis & McDonagh 1260 (K, MO); [Vatovavy-Fitovinany Region, Ifanadiana Distr.], Parc National Ranomafana, 21°15’S 47°27’E, c. 1100 m, 12.XI.1991, Malcomber et al. 1052 (MICH, MO, P). Prov. Toamasina: Alaotra-Mangoro Region, Moramanga Distr., Ambatovy, 18°51’32”S 48°19’02”E, 1095 m, 30.X.2005, Antilahimena & Edmond 3894 (G, K, MO, P, TAN); ibid. loc., 21.X.2005, Antilahimena & Edmond 4091 (K, MO); ibid. loc., 18°51’58”S 48°17’11”E, 1012 m, 26.I.2007, Antilahimena 5221 (MO, P, TAN); Sahaviana forest, 18°51’33”S 48°17’10”E, 999 m, 14.II.2007, Antilahimena 5339 (MO, P, TAN); Maharombotra forest, 18°51’45”S 48°16’13”E, 982 m, 11.X.2008, Antilahimena et al. 6676B (MICH, MO, P, TAN); Ankoditrazo forest, 18°50’06”S 48°15’50”E, 954 m, 24.II.2009, Antilahimena et al. 6978 (MO, P, TAN); ibid. loc., 18°50’11”S 48°15’51”E, 967 m, 24.II.2009, Antilahimena et al. 6981 (MICH, MO, P, TAN); Ankosy forest, 18°49’13”S 48°16’11”E, 1031 m, 21.IV.2009, Antilahimena et al. 7057 (MICH, MO, P, TAN); Savaharina forest, 18°52’08”S 48°20’26”E, 1065 m, 12.XI.2009, Antilahimena & F. Edmond 7174 (MICH, MO, P, TAN); Antsinanana Region, Brickaville, Anjahamamy, Anivoranokely, Ankerana forest, 18°24’26”S 48°49’23”E, 676 m, 25.I.2012, Antilahimena 8064 (MO, P, TAN); Moramanga Distr., Andasibe, Mantadia National Park, 18°47’54”S 48°25’35”E, 961 m, 20.III.2013, Antilahimena et al. 8614, (MICH, MO, P, TAN); Andasibe, Analamazaotra, 18°55’31”S 48°25’58”E, 1025 m, 18.II.1990, Bernard et al. 1990 (MICH, MO, P, TAN); Anony, pays Sihanaka, 3.IX.1937, Boiteau & Cours 2954 (P); Moramanga, Route d’Anjiro, 900 m, XI.1938, Cours 803 (P); Ambatondrazaka Distr., Onibe, 800-1000 m, XI.1938, Cours 988 (P); Manambato à Amboditfonana, 1200 m, 11.X.1945, Cours 2833 (P); Zahamena, 22.III.1941, Decary 16708 (P); chutes du Maningory, XII.1944, Homolle 537 (P); Ambatovy, 1.VII.1966, Peltier 5997 (K, P); ibid. loc., 18°51’34”S 48°18’25”E, 1050 m, 3.III.1997, Rakotomalaza et al. 1220 (MO, P, TEF); Analamazaotra, 18°56’07”S 48°25’52”E, 1014 m, 19.XII.2013, Ramahenina et al. 320 (MO, P, TAN); Ambatondrazaka Distr., Manakambahiny-Est, Anosivola, Zahamena, 17°43’42”S 48°40’27”E, 875 m, 2.XI.2001, Randrianasolo et al. 259 (CNARP, DAV, MO, P, TEF); Ambatoaranana, Corridor Forestier Analamay Mantadia, 18°47’38”S 48°24’39”E, 1019 m, 23.IV.2012, Rasoazanany & Ratolojanahary 77 (MICH, MO, P, TAN); Analamazaotra, Amboasary, 18°57’13”S 48°26’43”E, 1008 m, 14.II.2013, Rasoazanany et al. 324 (MICH, MO, P, TAN); Ambatovy, 18°51’46”S 48°16’14”E, 984 m, 20.II.2010, Rasolofoniaina et al. 14 (MO, P, TAN); Ambatondrazaka, Manaka Est, 2.XI.1962, Réserves Naturelles 12231 (P, TEF); Ambatondrazaka, Maheriara, 11.VII.1954, Service Forestier 10543 (P); Ambatovy, 18°51’52”S 48°16’30”E, 1004 m, 22.III.2016, van Ee et al. 2464 (MICH, MO, P, TAN); ibid. loc., van Ee et al. 2465 (MICH, MO, P, TAN); ibid. loc., 18°52’08”S 48°20’26”E, 1053 m, 23.III.2016, van Ee et al. 2469 (MICH, MO, P, TAN); ibid. loc., van Ee et al. 2470 (MICH, MO, P, TAN); ibid. loc., van Ee et al. 2471 (MICH, MO, P, TAN); ibid. loc., 2472 (MICH, MO, P, TAN); Analamazaotra, 24.X. 1912, 900 m, Viguier & Humbert 989 (P). Prov.Toliara: Anosy Region, Betroka Distr., Ivahona, Réserve Spécial de Kalambatritra, forêt d’Analamaro, 23°28’14”S 46°23’38”E, 1390 m, 4.XI.2005, Andrianjafy et al. 446 (MO, P, TAN); ibid. loc., 23°25’12”S 46°26’45”E, 1359 m, 23.V.2005, Andrianjafy et al. 1070 (K, MO, P, TAN).
description: Published as part of 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, pp. 327-356 in Candollea 71 (2) on pages 344-347, DOI: 10.15553/c2016v712a17, http://zenodo.org/record/5721805