Psychotria antilahimenae C.M. Taylor, 2020

Taylor, Charlotte M., Gereau, Roy E. & Schmidt, Heidi H., 2020, Some distinctive new species of Psychotria (Rubiaceae, Psychotrieae) from Madagascar, Candollea 75 (2), pp. 159-182 : 162-164

Psychotria antilahimenae C.M. Taylor , sp. nov. ( Fig. 2A–E ).

Holotypus: MADAGASCAR. Reg. Analanjirofo [ Prov. Toamasina ]: Nosy Mangabe , 15°50'S 49°46'E, 0–330 m, 10.X.1987, Schatz 1619 ( MO-3586737 !; isotype: K, P, TAN) .

Psychotria antilahimenae C.M. Taylor is distinguished from P. simianensis A.P. Davis & Govaerts by its 5-merous flowers, longer calyx, and white corollas.

Shrubs, collected in flower and fruit variously at 0.3–1.5 m tall, unbranched (i.e., monopodial), sometimes accumulating detritus along stem inside leaf bases; stems flattened to subterete, smooth, glabrous. Leaves opposite; petiole 0.2–1 cm, glabrous or puberulous with trichomes 0.1 –0.2 mm; blade obovate to oblanceolate, 18–35 × 4–14.5 cm, at base tapered then acute to obtuse, at apex obtuse to rounded then shortly abruptly acuminate with tip 3–10 mm, drying papyraceous to chartaceous, adaxially glabrous, abaxially glabrous or occasionally densely puberulous on costa with trichomes up to 0.1 mm; secondary veins 14 to 20 pairs, looping to interconnect near margins, without domatia, on both surfaces costa prominent, secondary veins prominulous, and remaining venation plane and not evident or sometimes one intersecondary vein evident between pairs of secondary veins and infrequently some tertiary venation evident and prominulous. Stipules interpetiolar, caducous, triangular, c. 25 mm, acute, abaxially glabrous and costate, adaxially glabrous. Inflorescences terminal, subcapitate to congested-cymose, pedunculate, glabrous; peduncle 1–5 cm; flower-bearing portion hemispherical to irregularly subglobose, 1–3 × 1.5–3 cm, unbranched or shortly branched to 1 order, 20- to 140-flowered; bracts reduced or few, ovate, 0.5–1 mm; pedicels 1–2 mm. Flowers all pedicellate in cymes of 3- to 7, 5-merous; hypanthium narrowly ellipsoid, c. 1 mm, glabrous; calyx limb 1–1.2 mm, glabrous, denticulate or lobed for up to 1/3 of its length, lobes narrowly triangular, acute; corolla tubular, white, externally glabrous, tube c. 3 mm, c. 1.2 mm diam. near middle, internally glabrous except pilose in throat with white trichomes 1– 1.5 mm, lobes narrowly triangular, c. 2.5 mm, acute, adaxially plane to shortly galeate, abaxially smooth; stamens with filaments c. 1 mm, inserted near top of corolla tube, anthers narrowly oblong, 1–1.2 mm, exserted; style c. 2 mm, stigmas c. 0.8 mm, included. Infructescences similar to inflorescences or becoming laxer, to 4 × 4 cm. Fruits ellipsoid to subglobose, 8–9 × 7–8 mm, glabrous, red, with calyx often enlongating, to 2 mm; pyrenes hemispherical, adaxially plane, abaxially with c. 6 well developed, rounded, longitudinal ridges; endosperm sparsely ruminate to a moderate depth on all sides.

Etymology. – This distinguished, handsome species has been documented by Mr. Patrice Antilahimena, an exceptionally productive explorer of Madagscar’s flora who has collected more than 11,000 high-quality specimens, and the species epithet honors him.

Habitat, distribution and phenology. – Psychotria antilahimenae has been collected in perhumid evergreen forest at 0–600 m on the Masoala Peninsula in northeastern Madagascar (Antsiranana, Toamasina), with flowers in February, October , and November and with fruits in April through July .

Conservation status. – Psychotria antilahimenae is known from 11 specimen collections representing nine unique occurrences in perhumid evergreen forest. The EOO of the species is 2,407 km ², within the limits for “Endangered” under IUCN Red List Criterion B1; and the AOO is 32 km ², also within the limits for “Endangered” under Criterion B2 ( IUCN, 2012). One occurrence is within the well-protected Masoala PA, two occurrences are within Nosy Mangabe PA, and the other six occurrences are in unprotected areas adjoining but distinctly outside Masoala PA and Makira PA. Forested areas without formal protection in the vicinity of Masoala PA and Makira PA are subject to degradation by small-scale slash and burn agriculture and mineral exploitation ( GOODMAN et al., 2018). Six locations (sensu IUCN, 2012) can be defined relative to the known threats: the one collection site within Masoala PA; the two collection sites within Nosy Mangabe PA; the three collection sites near Ambanizana just west of Masoala PA; and one location for each of the collection sites to the northeast and northwest of Masoala PA and near the east edge of Makira PA. With six locations, given general habitat degradation in unprotected sites and with no reason to assume that any of the unprotected sites is more likely to disappear than the others, the Red List status of P. antilahimenae is assessed as “Vulnerable” [VU B1ab(iii)+2ab(iii)].

Notes. – Psychotria antilahimenae is characterized by its unbranched or little-branched habit with well developed, subsessile to shortly petiolate, obovate leaves; pedunculate, subcapitate to shortly cymose inflorescences; five-merous flowers; somewhat short, subtruncate to dentate calyx limbs; short white corollas; red fruits; abaxially ridged pyrenes; and endosperm that is ruminate on all surfaces. The habit of this species is found in only a small percentage of Psychotria species worldwide, and has sometimes been called a “trash bucket” habit due to the detritus that is accumulated along the stems by the closely set leaves. No adventitous roots were seen along the stems in the specimens studied here, but these are sometimes found growing into the accumulated detritus in other “trash bucket” species. The inflorescences and infructescences are terminal on all the specimens studied, but one well developed axillary bud subtends the infructescence of one collection (Zjhra & Hutcheon 318): the unbranched stem may at least sometimes continue its growth from this position, so the plants may be able to flower and fruit more than once. In contrast, another specimen (Zjhra & Hutcheon 174) bears two peduncles from the stem apex, so some plants may have determinate stems, or be able to branch. The flowers are described on one collection (Lowry et al. 4243) as having an “unpleasant odor suggesting fly pollination”; however, the flowers have showy (though small), bright white corollas with barbate throats and exserted anthers that are not usually suggested to be correlated with fly-pollination. The few flowers seen agree with the short-styled form of distylous Psychotria species , but whether this species is distylous is not yet known. The flowers are pedicellate at anthesis but usually borne in short congested groups, then later the inflorescence axes develop and the fruits become separated from each other as they mature. Psychotria antilahimenae agrees with BREMEKAMP (1963) ’s Mapouria Group VI.

Psychotria antilahimenae is similar to P. simianensis , the only other Psychotria species known so far from Madagascar with a monopodial, “trash-bucket” habit. Psychotria simianensis can be separated by its dried leaves with regularly reticulated tertiary and quaternary venation that is prominulous on both leaf surfaces, 6- or 7-merous flowers, shorter calyx limbs c. 0.5 mm long, and yellow corollas. In the classification used here, P. simianensis includes only plants that agree with these particular characteristics, and is now only documented from the area of Mananara on Madagascar’s mainland. This circumscription of P. simianensis includes plants that match the type of that species, but excludes additional specimens that have been subsequently identified as this species but do not match it (Taylor, in prep.).

Paratypi. – MADAGASCAR. Reg. Analanjirofo [ Prov. Toamasina ]: Maroantsetra , Anjahana , Ambanizana , 15°38'03"S 49°58'47"E, 7.V.2002, Antilahimena 1049 ( BR, K, MO, P, TAN); Andranobe, env. 8 km S of Ambanizana, 15°39'32"S 49°57'31"E, 10 m, 18.I.2006, Raharimampionona 115 ( MO, NY, P, TEF); Ambanizana, trail A behind MBG House , 15°39'30"S 49°57'30"E, 600 m, V.1993, Zjhra & Hutcheon 318 ( K, MO); Antsirabe Sahatany, Anjiahely , 15°24'16"S 49°30'41"E, 393 m, 27.V.2004, Antilahimena 2583 ( MO, P, TAN); hills E of village of Sahavary , up Andranofotsy riv. from Maroantsetra , [15°19'S 49°52'E], 300 m, 24.X.1986, Lowry et al. 4243 ( K, MO); Masoala Peninsula, W of Ambohitralanana , forest near Sahafary , 15°16'S 50°22'E, 75 m, 19.VI.1997, McPherson 17105 ( MO); ibid. loco, Antalavia , following coastal path leading S , 15°46'S 50°01'E, 25 m, 17.IV.1987, Nicoll et al. 563 ( K, MO); RS Nosy Mangabe , 15°30'S 49°47'E, 215 m, 22.IV.1987, Nicoll & Schatz 597 ( K, MO); ibid. loco, 15°30'S 49°46'E, 0–330 m, 6–8.V.1998, Schatz et al. 2374 ( K, MO). Reg. SAVA [ Prov. Antsiranana ]: Masoala Peninsula , forest surrounding research station at Andronabe on W coast , 15°39'30"S 49°57'30"E, 0–600 m, 19.II.1992, Zjhra & Hutcheon 174 ( MO).

Figures

Fig. 2. – Psychotria antilahimenae C.M. Taylor: A. Flowering branch; B. Flower bud; C. Corolla at anthesis; D. Fruit; E. Cross-section of pyrene and seed. Psychotria davisiana C.M. Taylor: F. Flowering branch; G. Stem apex with bases of two leaves and a stipule; H. Stem apex with bases of two petioles, one stipule, and one flower at anthesis; I. Fruit; J. Cross-section of pyrene and seed. [A–C: Schatz 1619; D–E: Schatz et al. 2374; F–G: Randrianasolo et al. 511 (isotype); H: Randrianaivo et al. 511 (holotype); I–J: Miandramana 398]