Acalypha crateriana (Coode) I.Montero & Cardiel, 2023

Muñoz, Iris Montero, Levin, Geoffrey A. & Cardiel, José María, 2023, Monograph of Acalypha L. (Euphorbiaceae) of the Western Indian Ocean Region, with the description of a new species from Mayotte, Adansonia (3) 45 (26), pp. 395-496 : 430-431

12. Acalypha crateriana (Coode) I.Montero & Cardiel , comb. nov.

Acalypha integrifolia Willd. subsp. marginata (Poir.) Coode var. crateriana Coode, Kew Bulletin 34: 44 ( Coode 1979). — Type: Mauritius. Tamarin Falls, 2.III.1975, D. Lorence 1138 (holo-, K[K000431104]; iso-, K[K000431105], MAU[n.v.]).

ICONOGRAPHY. — Unknown.

ETYMOLOGY. — The epithet probably refers to the Kanaka crater in Mauritius.

DISTRIBUTION AND HABITAT. — Endemic to the Mascarene Islands ( Mauritius). Degraded lowland evergreen moist forest. Altitudinal range 700-800 m ( Fig. 26 ).

PRELIMINARY CONSERVATION ASSESSMENT. — Acalypha crateriana comb. nov. is only known from Kanaka crater and Grand Bassin peak in Mauritius. Its EOO is estimated to be 12.9 km 2 and its AOO 12 km 2. Native forest remnants of Mauritius are very restricted, covering less than 5% of the total landmass. This massive deforestation is due mainly to agriculture and urban expansion. Another threat to the Mauritius native flora is the widespread occurrence of alien species. Native plants are seriously affected by invasive plants, reducing their growth rate so regeneration of forests is extremely low ( Safford 1997; Florens 2008; Baider & Florens 2013; Norder et al. 2017). No specimens of this species have been collected for 45 years. In recognition of its restricted geographic range (a single known location), the cited threats, and the absence of recent collections, A. crateriana comb. nov. is assigned a preliminary conservation status of Critically Endangered: CR B2ab(ii,iii,iv).

MATERIAL EXAMINED. — 16 collections. Mauritius. Coode, M.J.E. 4694 (K), 4700 (K), 4701 (P[P04779343]), 4704 (K), 4705 (K, MO[MO-2452045]), 4718 (K), 4720 (K), 4721 (P[P04779349]), 4722 (K), 4729 (K), 4732 (K, MO[MO-2452041]), 4737 (K), 4744 (K, MO[MO-2452042]), 4748 (P[P04779342]); Lorence, D. 1138 (K[K000431104, K000431105]), DL1858 ( MO [MO-2452048], P[P04779346]).

REFERENCES. — Coode (1982: 74); Montero Muñoz et al. (2018a: 104) as A. marginata .

DESCRIPTION

Shrubs, leaf persistence unknown, to 2.7 m tall, probably dioecious. Branches appressed-pubescent, glabrescent when mature. Axillary buds naked, hispid. Stipules to 5 mm long, linear-lanceolate, densely pubescent with simple, appressed trichomes, margin papillate. Petioles 0.5-0.8 cm long, indumentum similar to that on young branches, glabrescent. Leaf blades 4-7(-10) × 1.5-3cm, elliptic to subobovate, chartaceous; base acute to cuneate; apex rounded to acute; margin crenate to crenate-dentate, slightly revolute, usually reddish or pinkish, teeth rounded; upper surface glabrous; lower surface sparsely hairy with appressed trichomes on veins; venation pinnate, secondary veins 7-8 per side. Stipels absent. Inflorescences spiciform (male) or glomerulate (female), unisexual, axillary. Male inflorescences to 5 cm long; peduncle to 5 mm long, indumentum similar to that on petioles; flowers glomerate; bracts to 1 mm long, triangular, appressed-pubescent. Female inflorescences 2-4 mm long;sessile; bracts 1-4, not enlarging in fruit, to 0.5 mm long, triangular-lanceolate, appressed-pubescent; margin entire; bracteoles absent. Male flowers: pedicel to 0.6 mm long, sparsely hairy; buds to 0.5 mm diameter, sparsely hairy. Female flowers 1 per bract, subsessile; sepals 3, to 1 mm long, triangular-lanceolate, appressed-pubescent; ovary c. 1 mm diameter,3-lobed,papillose, surface densely hispid; styles 3, to 4 mm long, distinct, sparsely hairy on rachis, each divided into 10-11 segments. Allomorphic flowers not seen. Capsules to 3 mm diameter, papillose-hispid, papillae ending in a simple, trichome to 1 mm long, surface sparsely hairy with simple, short trichomes, glabrescent. Seeds c. 1 × 0.7 mm, pyriform, minutely foveolate.

NOTE

Acalypha crateriana comb. nov. was treated by Coode (1979) as variety of A. integrifolia subsp. marginata , treated here as A. marginata . We consider A. crateriana comb. nov. to be a distinct species distinguished mainly by having petioles 0.5- 0.8 cm long and leaf blades 4-7(-10) × 1.5-3 cm, elliptic to subobovate; base acute to cuneate; apex rounded to acute; margin crenate to crenate-dentate, usually reddish or pinkish, slightly revolute, teeth rounded; vs petioles 0.5-3 cm long and leaf blades (4-)6-17-(21) × (2-)2.5-7(-8) cm, usually elliptic to elliptic-lanceolate, sometimes obovate; base rounded to cuneate; apex acute to subacuminate; margin crenate-serrate to serrate, discolorous, teeth rounded to acute, slightly callose-edged in A. marginata .

Figures

FIG. 26. — Distribution map of Acalypha crateriana (Coode) I.Montero & Cardiel, comb. nov. in Mascarene Islands.