Psychotria hamifera 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 : 171-174

Psychotria hamifera C.M. Taylor , sp. nov. ( Fig. 5A–E ).

Holotypus: MADAGASCAR. Reg. Analanjififo [Prov. Toamasina ]: Maroantsetra , Ambinanitelo , Marovovonana , nearest village Ambatofotsy , Mangabe forest , 15°17'40"S 49°29'15"E, 690 m, 30.VIII.2004, Antilahimena 2657 ( MO-6877030 !; isotype: G [ G00341935 ]!, P, TAN) .

Psychotria hamifera C.M. Taylor is distinguished from other Psychotria species in Madagascar by its the combination of the cupuliform shape and length, 20 –25 mm long, of the stipules.

Shrubs and small trees, collected in flower and fruit variously at 2.5–6 m tall, branched; stems stout, weakly flattened becoming subterete, glabrous. Leaves opposite; petiole 2.5–5 cm, glabrous; blade obovate, 12.5–30 × 5–15 cm, at base tapered and acute, at apex obtuse to rounded or truncate and shortly acuminate with deltate tip 2–5 mm, drying papyraceous, on both surfaces glabrous; secondary veins 11 to 19 pairs, reticulating near margins with higher-order venation or sometimes weakly looping to interconnect, without domatia, with 1 well developed intersecondary vein between pairs of secondary veins, on both surfaces costa and secondary veins prominent, intersecondary veins prominent to plane, and loosely reticulated tertiary venation plane to thinly prominulous. Stipules united around stem into a tube, in bud with top portions pressed together with their margins reflexed, at maturity funnelform, persistent with the leaves or tardily deciduous, falling off as a tube around stem, 15–30 mm, on each interpetiolar side with the basal 1/3–1/2 of their length triangular and smooth, at top truncate to undulate, glabrous abaxially, adaxially glabrous except densely pubescent on basal smooth portion with trichomes 1–3 mm, with upper portions of tube densely longitudinally venose or fibrous and this visible on one or both sides depending on age and preservation of the stipule. Inflorescences terminal, branched, glabrous, subsessile to shortly pedunculate; peduncle to 0.5 cm; branched portion rounded-corymbiform, c. 6 × 6 cm, branched to 2 or 3 orders, c. 35- to 50-flowered; bracts triangular and 0.1–0.5 mm or reduced and represented by a tuft of hirtellous trichomes 0.2–0.5 mm; pedicels 2–5 mm. Flowers all pedicellate in umbelliform cymes of 5 to 7, 5- or 6-merous; hypanthium obconic, c. 2 mm, glabrous; calyx limb 5–7 mm, glabrous, fleshy, lobed for c. 1/5 of its length, lobes narrowly triangular, acute; corolla salverform, orange, fleshy, externally glabrous, tube 5–6 mm, cylindrical, c. 3 mm diam. near middle, internally glabrous except densely pilose in throat with tichomes 2–3 mm, lobes narrowly ligulate to triangular, 3–4 mm, obtuse, adaxially shortly galeate, abaxially with conical thickening c. 1 mm; stamens with filaments c. 1 mm, inserted in upper part of corolla tube, anthers c. 1.5 mm, exserted; style c. 2 mm, stigmas c. 1.5 mm, included and positioned below ring of corolla pubescence. Infructescences similar to inflorescences or becoming laxer, with pedicels to 8 mm. Fruits ellipsoid, 12– 15 × 7–10 mm, glabrous, orange, texture unknown; pyrenes hemispherical, abaxially with 5 or 6 low, rounded to angled ridges, adaxially glabrous; endosperm densely ruminate on all surfaces.

Etymology. – The stipules of this new species resemble buckets or pails, and its species epithet refers to this feature.

Habitat, distribution and phenology. – Psychotria hamifera has been collected in perhumid evergreen forest at 383–861 m on the Masoala Peninsula and nearby eastern escarpment of Madagascar (Antsiranana, Toamasina), with flowers in December and with well-developed fruits in January , February , May , July , and August .

Conservation status. – Psychotria hamifera is known from six specimen collections representing six unique occurrences in perhumid evergreen forest at 383–861 m elevation. The EOO of the species is 889 km ², within the limits for “Endangered” under IUCN Red List Criterion B1; and the AOO is 24 km ², also within the limits for “Endangered” under Criterion B2 ( IUCN, 2012). Three occurrences are within the generally wellprotected Makira PA, and one occurrence is within Masoala PA. The coordinates of its remaining two collection sites map outside Makira PA, but one of them (Davis et al. 4534) has label data indicating that it is inside Makira PA in an area with “minimal disturbance”. The interiors of the reserves are well protected but parts close to villages are seriously impacted by exploitation of timber and, to a lesser extent, shifting cultivation (C. Birkinshaw, pers. comm.). 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). The one occurrence definitely outside Makira PA constitutes one location (sensu IUCN, 2012) with respect to the known threats; and the occurrences within each protected area constitute a location each for a total of three locations. With one location subject to general habitat degradation and the remaining two locations in protected areas, the Red List status of P. hamifera is assessed as “Endangered” [EN B1ab(iii)+2ab(iii)].

Notes. – Psychotria hamifera is characterized by its robust leaves with obovate blades that are obtuse to rounded or truncate and shortly acuminate at the tip; unusual, large, persistent, tubular stipules; cymose, subsessile to shortly pedunculate inflorescences with pedicellate flowers; well developed truncate calyx limbs; orange, somewhat large corollas; well developed fruits that become orange; and endosperm that is densely ruminate on all sides. The dried specimens seen have a strong reddish brown color. The stipules are distinctive in Psychotria in the combination of their tubular, funnel- or skirt-shaped form, persistence, and relatively large size; among the previously known species of Psychotria , they are similar only to those of P. retusa (Bremek.) A.P. Davis & Govaerts , another endemic Malagasy species. These stipules are also similar to those of P. palifera , which is newly described below. The inflorescences have relatively short axes and flowers that are rather closely grouped at anthesis, but the axes and pedicels elongate as the fruits develop so the infructescences are quite lax. The calyx limbs are apparently fleshy, and enclose the corollas from young to quite mature buds and mostly cover the fully developed corolla tubes. The few flowers seen are similar to the short-styled form of distylous Psychotria species , but whether P. hamifera is distylous cannot yet be determined. The fruits are relatively large for Psychotria , but similar in size to some other Malagasy Psychotria that are hypothesized to possibly be dispersed by lemurs though without any actual documentation of their fruit dispersal. Data for the collection Davis 4535 describe the fruits as “ 7 cm in diameter” but this appears to be a typographical error for 7 mm. Psychotria hamifera agrees with Bremekamp’s Mapouria Group VI, although the fruits are sometimes larger than Bremekamp documented for this group.

Psychotria hamifera is similar to P. retusa , which differs in its leaf blades with retuse tips, caducous smaller stipules 9–10 mm long, shorter calyx limbs c. 0.5 mm long, and smaller fruits c. 5 mm in diameter. The mature corollas of P. retusa have not been documented; Bremekamp reported the corolla tubes in bud as c. 2.5 mm long and the lobes in bud as c. 1.2 mm long in bud, but the age of those buds was not noted.

Paratypi. – MADAGASCAR. Reg. SAVA [Prov. Antisanana ]: Antalaha-CR Vinanivao , CAP Masoala Grand , vallée d’Anaovanandrano , 15°44'S 50°10'E, 49 m, 16.IX.2003, Wohlhauser et al. 525 ( G, MO, NEU). Reg. Analanjirofo [Prov. Toamasina ]: Anjiahely , Vohitaly forest , 15°26'28"S 49°32'01"E, 540 m, 23.XII.2002, Antilahimena et al. 1594 ( MO, TAN); Sahantaha , 15°13'39"S 49°31'52"E, 600 m, 23.I.2003, Antilahimena 1778 ( MO, TAN); Anjiahely , 15°24'16"S 49°30'41"E, 393 m, 27.VI.2004, Antilahimena 2587 ( MO, TAN); Makira PA , c. 15 km due W of Ambinanitelo, 15°25'11"S 49°29'19"E, 400 m, 17.V.2007, Davis 4534 ( K, MO, TAN) .

Figures

Fig. 5. – Psychotria hamifera C.M. Taylor: A. Fruiting branch; B. Stipule at stem apex; C. Hypanthium and calyx limb of flower; D. Corolla at anthesis; E. Cross-section of pyrene and seed. Psychotria palifera C.M. Taylor: F. Fruiting branch; G. Stem apex with bases of two petioles and young stipules; H. Stem apex with bases of two petioles and older stipules; I. Portion of inflorescence with two flowers from which corollas have fallen and one flower bud; J. Corolla at anthesis; K. Cross-section of pyrene and seed. [A: Antilahimena 1778; B–D: Antilahimena 1594; E: Antilahimena 2657; F, K: Andrianjafy 368; G: Rasoandriana 169; H: Andrianjafy 371; I–J: Croat 32639]