Croton bathianus Leandri in Ann. Mus. Colon. Marseille, sér. 5, 7: 80. 1939

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 : 386-388

Croton bathianus Leandri in Ann. Mus. Colon. Marseille, sér. 5, 7: 80. 1939 [as bathiana] ( Fig. 1D , 2C , 4 G-H, 7).

Lectotypus (designated here): MADAGASCAR. Prov. Mahajanga: Haut Bemarivo , X.1907, Perrier de la Bâthie 9545 ( P [ P00301483] !; isolecto-: P [ P00127503 ]!). Syntypi: MADAGASCAR. Prov. Mahajanga: Maromandia, presqu’île Radama , 13.X.1922, Decary 1133 ( P [ P00389631 ]!), ibid. loc., 11.X.1922, Decary 1174 ( P [ P00301482 ]!); collines sèches du Haut Bemarivo , X.1906, Perrier de la Bâthie 9633 ( P [ P00389630 ]!).

Shrubs or small trees 2-4 m tall, dichotomously branching, internodes sometimes so short as to give the appearance of whorled branches. Branches flattened on new growth but becoming terete with age, young shoots pale green and densely covered with a reddish, granulate, stellate indument, soon turning glabrous and matte pale gray. Stipules 4-20 × 1.2-2 mm, lanceolate, early caducous. Leaves opposite. Petioles 2-9(-43) cm, adaxially canaliculate, stellate, usually with a pair of subsessile, concave, discoid acropetiolar glands (0.5-1 mm diam.). Leaf blades chartaceous, subentire to shallowly undulate or denticulate, ovate, 5-16(-38) × 4-12(-30) cm, apex acuminate, base rounded to cordate; both sides with a persistent, scabrous stellate indument, green when fresh, drying matte brownish green; venation evident, with 6-11 pairs of brochidodromus, ± penninerved secondary veins (the lowermost pairs congested and appearing palmate), and cross-venulate tertiary venation; venation prominent abaxially, with conspicuous, stipitate, compressed-discoid glands in the axils of some of the secondary veins ( Fig. 1F ), rarely absent. Inflorescences terminal, raceme-like thryses 3-15 cm long, with 1-3(-4) pistillate flowers near the base and numerous staminate flowers in the upper ½ to 2/3, axes stellate, flattened; bracts ovate to triangular, c. 0.7-2.3 mm long, caducous. Staminate flowers with stellate, subglobose buds 2-2.6 mm diam., pedicels elongating from bud to anthesis, 1-5 mm long; sepals 5, pale green, shortly connate at base, lobes broadly triangular-ovate, 2-2.6 × 1.3-3 mm, apex acute, inflexed at anthesis, abaxially stellate-pubescent, adaxially sparsely pubescent, margins ciliate; petals 5, greenish white, elliptic to spatulate, 2-3 × 0.8-1.3 mm, recurved at anthesis, abaxially stellate and papillose, adaxially glabrous, margins densely ciliate; disc glands 5, opposite the sepals, sessile, triangular, truncate, c. 0.6 × 0.6 mm; stamens 12-17, white, filaments 1.5-2.7 mm long, glabrous, anthers broadly elliptic, 0.7-1 × 0.6-0.9 mm; receptacle pilose. Pistillate flowers with stellate-pubescent ellipsoid buds c. 2 mm diam., pedicels 1-5 mm long; sepals 5, elliptic-ovate, spreading at anthesis, 3-4.5 × 1.7-2 mm, apex acute, shortly connate at base, abaxially and adaxially stellatepubescent, persistent in fruit; petals, 3-3.5 × 1 mm, spatulate, abaxially stellate-pubescent and papillose, adaxially glabrous, margin ciliate; disc glands 5, opposite the sepals, sessile, ellipsoidal, 0.5 × 0.7 mm, yellow; ovary densely covered by ferrugineous to dark brown, stellate trichomes, globoid-ellipsoid, 2-3 mm diam., styles 3, 2- 2.5 mm long, each branch flattened and 3-4 times bifurcate, often with the first bifurcation congested and fused to appear 4 furcate, spreading, recurved at the apices, abaxially stellate-pubescent, adaxially glabrous, persistent. Capsules broadly globoid, 4.5-5.6 × 6.5-7.5 mm, smooth, pale brown, covered with dark brown stellate trichomes ( Fig. 4G ), exocarp not separating, endocarp woody, 0.5-0.7 mm thick; columella 3.0- 4.5 mm long, cornute, capitate, the angles fimbriate. Seeds ± compressed-ellipsoid, 3.3-4 × 2.5-3 × 2-2.5 mm ( Fig. 4H ); testa glossy, verrucose, brown; caruncle reniform, 0.4-0.7 × 0.7-1.3 mm.

Phenology. – Specimens in flower have been collected in August, October, November, February and March and in fruit in March and November.

Distribution, habitat and ecology. – Croton bathianus inhabits remnants of semi-deciduous and semi-evergreen forests in Antsiranana and Mahajanga Provinces, from near sea level to roughly 400 m elevation ( Fig. 2C ). It is sometimes cultivated in hedgerows, either to delimit parcels of land or as a shade plant, and it is sometimes coppiced and then produces gigantic leaves (see the upper extremes of leaf dimensions above).

Conservation assessment. – Croton bathianus was first described from three collections from the hills in the “haute Bemarivo” of Mahajanga Province in the XXth century that probably represent three different locations. We found at least six more locations of this species in semi-deciduous to semievergreen forests in Antsiranana and Mahajanga Provinces in the last two decades. Even if this species has a substantial geographical range, the populations are severly fragmented. We therefore consider this species as “Near Threathened” [NT] according the IUCN Red List Categories and Criteria ( IUCN, 2012).

Vernacular names. – “Hazomafaitra” (van Ee et al. 2290).

Notes. – Croton bathianus was named in honor of J.M.H.A. Perrier de la Bâthie (1873-1958), who collected the type and collected extensively throughout Madagascar.

This species can be distinguished by the rusty-reddish, granulate pubescence on young shoots ( Fig. 7E ), with the stems soon turning glabrous, dull gray, and striate. The glands in the vein junctions on the lower side of the leaves can be among the largest and most conspicuous found on any Croton species. Compared to the other species of the Adenophorus Group from northern Madagascar, C. bathianus has more compact inflorescences, with the pistillate flowers in particular often being nearly sessile, as well as having well-developed petals ( Fig. 7 G-H). Like C. adenophorus , this species is sometimes cultivated, and it is used for hedgerows (e.g., van Ee et al. 2406). Coppiced plants have been observed to grow enormous leaves, to c. 38 × 30 cm ( Fig. 7 A-B). LEANDRI (1939) indicates in his protologue that the diagnosis of the species was done based on characters noted by Perrier de la Bâthie in living specimens. The lectotype selected above includes a lengthy description in the hand of Perrier de la Bâthie, with a note on the top saying “sur le frais” (from fresh material).

RADCLIFFE-SMITH (2016) recognized three additional varieties under Croton bathianus . We consider C. bathianus var. ihosianus Radcl. -Sm. to be a synonym of C. ihosianus Leandri , C. bathianus var. toliarae Radcl. -Sm. to be a synonym of C. crocodilorum Leandri , and C. bathianus var. ambatondrazakae Radcl. -Sm. to be a synonym of C. scoriarum Leandri.

Additional specimens examined. – MADAGASCAR. Prov. Antsiranana: Diana Reg., RN 6 , 43 km N of Ambanja, 13°30’33”S 48°41’51”E, 20 m, 2.XI.2009, van Ee et al. 1138 ( MICH); ibid loc., van Ee et al. 1139 ( MICH); ibid loc., van Ee et al. 1140 ( MICH); RN 6 , just north of the turnoff to Belinta , 13°30’47”S 48°41’44”E, 24 m, 27.II.2016, van Ee et al. 2289 ( MICH, TAN); ibid loc., van Ee et al. 2290 ( MICH, TAN); RN 6 E of Ampampamena , 13°30’46”S 48°40’30”E, 34 m, 27.II.2016, van Ee et al. 2296 ( MICH, TAN); along RN 6 , at village of Ambatoharanana , 13°30’46”S 48°41’44”E, 33 m, 8.III.2016, van Ee et al. 2383 ( MICH, TAN). Prov. Mahajanga: Sofia Reg., Analalava Distr ., Route Nationale 6 , gorge off to the E of highway between PK 359 and 360 , 14°23’26”S 48°01’14”E, 30 m, 22.X.2009, Van Ee et al. 1043 ( MICH, TAN); RN 6 , between PK 388 and 389 , 14°10’20”S 48°05’32”E, 20 m, 22.X.2009, Van Ee et al. 1048 ( MICH, TAN); RN 6 approximately 18 km N of Port Berge ( Boriziny ), 15°27’47”S, 47°35’57”E, 97 m, 26.II.2016, Van Ee et al. 2282 ( MICH, TAN); RN 6 , between PK 170 and 171 , north of Port Berger , 15°30’07”S 47°34’58”E, 115 m, 9.III.2016, van Ee et al. 2406 ( MICH, TAN); track heading into Bongolava Hills to west of RN6 , 15°33’10”S 47°33’31”E, 79 m, 10.III.2016, van Ee et al. 2408 ( MICH, TAN); ibid loc., van Ee et al. 2409 ( 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. 7. Croton bathianus Leandri A. Coppiced individuals; B. BVE with a sucker shoot; C. Leaves; D. Stipules; E. Young leaves and inflorescence; note the dense covering of ferrugineous, granulate trichomes; F. Staminate flowers; G-H. Inflorescence with staminate and pistillate flowers; note the presence of petals in the pistillate flowers; I. Young fruits. [A: van Ee et al. 1139; B: van Ee et al. 2290; C, I: van Ee et al. 1140; E: van Ee et al. 2296; D, F: van Ee et al. 2383; G-H: van Ee et al. 2289] [Photos: A: B. van Ee; B-I: P. Berry]