Psychotria birkinshawiana 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 : 164-168

Psychotria birkinshawiana C.M. Taylor , sp. nov. ( Fig. 3A–E ).

Holotypus: MADAGASCAR. Reg. Analanjirofo [ Prov. Toamasina ]: Maroantsetra , hills E of village of Sahavary , up Andranofotsy River from Maroantsetra , along trail toward headwaters of Sahafotra River ( Ravim Bé swamp ), [15°19'S 49°52'E], 300 m, 24.X.1986, Lowry et al. 4248 ( MO-3436895 !; isotype: K, P, TAN) .

Psychotria birkinshawiana differs from P. nossibensis A.P. Davis & Govaerts and P. humblotii (Bremek.) A.P. Davis & Govaerts by its shorter calyx limbs, smaller corollas, and smaller fruits.

Small trees, collected in flower and fruit variously at 4–9 m tall, branched; stems flattened when young quickly becoming subterete, smooth, glabrous, at apex sometimes with shiny exudate on stipules and young leaves. Leaves opposite; petiole 0.5–2.5 cm, glabrous; blade obovate to oblanceolate or narrowly elliptic, 4.5–15 × 1.8–7.5 cm, at base acute to cuneate, at apex obtuse to rounded or truncate, drying chartaceous, on both surfaces glabrous; secondary veins 8 to 28 pairs, looping to interconnect near margins, without domatia, on both surfaces costa thickened and remaining venation plane and not evident. Stipules interpetiolar or shortly fused around stem, caducous, ovate to broadly triangular, 4–12 mm, obtuse to rounded, abaxially glabrous, adaxially densely sericeous to strigose with silky trichomes 1–2 mm. Inflorescences terminal, cymose, subsessile (i.e., apparently fasciculate), glabrous or with patches of sericeous trichomes 1–2 mm at nodes; peduncle reduced, represented by a leafless node with reduced stipule borne immediately above distalmost leaf-bearing node of stem; flower-bearing portion corymbiform, 2–3 × 2–4 cm, branched to 1- or 2 orders, c. 25- to 70-flowered; bracts triangular, 0.2–0.5 mm, adaxially sericeous with trichomes 1–2 mm. Flowers all subsessile in clusters of 5 to 7, subtended by sericeous trichomes 1–2.5 mm, 5-merous; hypanthium obconic, 1.2–1.5 mm, glabrous; calyx limb 1.5–2.2 mm, glabrous, truncate to irregularly subtruncate; corolla salverform, yellow, externally glabrous, tube cylindrical to weakly funnelform, 2.5–3 mm, 1–1.2 mm diam. near middle, internally densely tomentulose-pilosulous with white trichomes 0.5–1 mm in a zone just above middle of tube but not extending into throat, lobes narrowly triangular, c. 2 mm, acute, fleshy, adaxially shortly galeate, abaxially with rounded to conical low thickening near tip; stamens with filaments c. 1 mm, inserted below top of corolla tube, anthers narrowly oblong, c. 1 mm, positioned with tips in corolla throat; style c. 3.5 mm, stigmas c. 1 mm, included. Infructescences similar to inflorescences or becoming laxer, to 4 × 8 cm. Fruits subglobose, 10–15 mm diam., glabrous, yellowish orange; pyrenes hemispherical, adaxially plane, abaxially smooth; endosperm densely and deeply ruminate on all sides.

Etymology. – The epithet of this very tall, apparently mammal-dispersed new species honors Dr. Christopher R. Birkinshaw, a lemur biologist who has contributed extensively to conservation in Madagascar.

Habitat, distribution and phenolog y. – Psychotria birkinshawiana has been collected in perhumid evergreen forest at 0–400 m, sometimes on sandy soils, on the Masoala Peninsula (Antsiranana, Toamasina), with flowers in October and with well-developed fruits in February, April-August, October, and November.

Conservation status. – Psychotria birkishawiana is known from 23 specimen collections representing 19 unique occurrences in perhumid evergreen forest at 0–400 m elevation. The EOO of the species is 7,290 km ², within the limits for “Vulnerable” under IUCN Red List Criterion B1; and the AOO is 68 km ², within the limits for “Endangered” under Criterion B2 ( IUCN, 2012). Four of the 19 occurrences are within the well-protected Masoala PA. The remaining fifteen occurrences are in unprotected areas. Two of the collection sites have degraded or disturbed forest habitats. Forested areas without formal protection in the vicinity of Masoala PA are subject to degradation by small-scale slash and burn agriculture and resource exploitation, including logging, hunting and mining ( GOODMAN et al., 2018). Five collection sites indicate watershed/headwaters/river basin drainages as habitat; two sites have coastal habitat. The four occurrences within Masoala PA can be counted as one protected location (sensu IUCN, 2012, 2019), and the remaining, unprotected occurrences can be grouped into nine additional locations based on geographic clustering relative to the scale of threats, some of them at high risk for further disturbance and exploitation due to their water resources. With ten locations and given general habitat degradation in unprotected sites, the sensitive nature of watershed areas, and no reason to assume that any of the unprotected sites is more likely to disappear than the others, the Red List status of P. birkishawiana is assessed as “Vulnerable” [VU B1ab(iii)+2ab(iii)].

Notes. – Psychotria birkinshawiana can be recognized by the combination of its robust habit; medium-sized, glabrous, obovate leaf blades that are obtuse to rounded at the apex; triangular, broadly angled stipules; rather short, cymose, terminal inflorescences with patches or tufts of dense sericeous pubescence along the axes and adaxially on the bracts; subsessile flowers with truncate calyx limbs; short yellow corollas; relatively well developed, yellow to orange fruits; and seeds with the endosperm densely ruminate on all sides. This species is notable in Malagasy Psychotria for its robust size. The leaves appear to be fleshy or rather succulent in life. 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 fruits are relatively large for Psychotria and appear on dried material to be fleshy rather than juicy, and their form suggests they may be eaten by lemurs (C. Birkinshaw, pers. comm.); whether these could be bird-dispersed has not been investigated. No ecological documentation is available for P. birkinshawiana , so its dispersers are only postulated here. Psychotria birkinshawiana agrees with BREMEKAMP (1963) ’s Mapouria Group III, which comprises species with a similar general aspect and relatively large fleshy fruits. The fruits of P. birkinshawiana range to a smaller size than Bremekamp gave for that group, which he diagnosed as having fruits 15–20 mm in diameter, but its largest fruits and other features agree with that group.

Psychotria birkinshawiana is similar to P. megalocarpa (Bremek.) A.P. Davis & Govaerts and P. humblotii , both of which are also found in eastern Madagascar. These others are only known from south of the range of P. birkinshawiana , however, and differ in their larger calyx limbs, 3–5 mm long; larger corollas, with the tube c. 8 mm long and lobes 4–5 mm long; and generally larger fruits, 15 – 20 mm in diameter, that may be green at maturity. Psychotria birkinshawiana is also similar to P. nossibensis A.P. Davis & Govaerts , which is found in northwestern Madagascar and has flowers and fruits that are similar in size and color to those of P. megalocarpa . Psychotria birkinshawiana is also similar to P. mangorensis (Bremek.) A.P. Davis & Govaerts , which is found in scattered localities along the east coast of Madagascar, south of the range of P. birkinshawiana , and possibly only on white sand soils. Psychotria mangorensis can be separated from all of these other species by its generally smaller fruits, 6–9 mm in diameter, that turn white as they mature then blue at maturity and its endosperm that is only ruminate on the adaxial side.

Paratypi. – MADAGASCAR. Reg. Analanjirofo [Prov. Toamasina]: Maroantsetra, Anjahana , Ambanizana , 15°38'12"S 49°58'15"E, 120 m, 10.VI.2002, Antilahimena & Arida 1073 ( MO, TAN) ; Andranofotsy , 15°25'10"S 49°49'06"E, 140 m, 14.VII.2002, Antilahimena et al. 1150 ( MO, TAN) ; Farankaraina forest , 15°26'30"S 49°51'00"E, 21.VI.2003, Antilahimena 1966 ( MO, TAN) ; Anjahana, Ambatoledama forest on way to Antalaha , 15°17 '00"S 50°00'00"E, VI.2003, Antilahimena 1997 ( MO, TAN) ; ibid. loco, Antilahimena 2024 ( MO, P, TAN) ; Bezavona forest , 2 km E of Sahavary village, 15°19'20"S 49°50'48"E, 244 m, 29.VIII.2009, H. Ralimanana et al. 1209 ( BR, G, K, MO, TAN) ; PN Masoala , Ambanizana , 15°37'S 49°58'E, 0–400 m, 2.IV.1996, Aridy 225 ( MO, P, TEF) ; Andranobe , 15°40'S 49°57'E, 200–300 m, 17.IV.1996, Aridy et al. 262 ( MO, P, TEF) ; 2–3 km W of Amebromanitra, near Ranomena riv. , 16°51'25"S 49°15'39"E, 450 m, 11.XI.1999, Davis & Rakotonasolo 2271 ( K, MO, TAN) ; S of Ambanizana , 15°41'S 49°58'E, 50–100 m, 12.II.1999, McPherson et al. 17567 ( K, MO, TAN) ; Tampolo , 15°43'S 49°57'E, 0–5 m, 31.X.1992, Schatz et al. 3376 ( MO) ; Andranobe, vicinity of Peregrine Fund site , [15°40'50"S 49°57'50"E], 270 m, 5.VII.2003, Sweeney et al. 1381 ( MO) ; S of Ambanizana in Andranobe riv. watershed , 15°40'24"S 49°57'51"E, 110–260 m, 25.X.1994, Vasey & Behasy 46 ( MO) ; ibid. loco, Vasey & Velo 346 ( K, MO, P, TAN) ; ibid. loco, Vasey & Velo 349 ( MO) ; Ambanizana , 15°39'30"S 49°57'30"E, 600 m, VI.1993, Zjhra & Hutcheson 322 ( K, MO) ; Andronobe, Camp Be-dinta , 15°39'30"S 49°57'30"E, 550–600 m, VII.1993, Zjhra & Hutcheon 509 ( K, MO) . Reg. SAVA [ Prov. Antsiranana ]: Masoala PN , à 22 km de la ville d’Ampanavoana, sur la route d’Ifasina , 15°41'S 50°15'E, 0–200 m, 1.II.1996, Aridy & Rahajasoa 102 ( MO, P, TEF) ; Antalaha, à 21 km du village de Sahamalaza sur la route de Vakoanina, Vinanivao , 15°48'S 50°18'E, 0–113 m, 15–16.II.1996, Aridy & MoÏse 138 ( MO, P, TEF) ; c. 10 km au S de Sahafary, à 3 km W du ruisseau de Sahalampona, 15°23'S 50°22'E, 100–200 m, 5.V.1995, Bernard 108 ( MO, P, TAN) ; Ampanavoana, Antalaha, Sanaenjika , 15°41'33"S 50°13'30"E, 12–100 m, 2.II.1996, Bernard et al. 150 ( MO, P, TAN) ; Ankavia, Mantazanina, Ambalavy , 15°20'10"S 50°14'07"E, 76 m, 20.X.2010, Bernard & Ndrano 1675 ( K, MO, P, TAN) .

Figures

Fig. 3. – Psychotria birkinshawiana C.M. Taylor: A. Flowering branch; B. Infrutescences with bases of two lateral stems; C. Portion of inflorescence with four flower buds; D. Corolla at anthesis; E. Cross-section of pyrene and seed. Psychotria razafimandimbisonii C.M. Taylor: F. Flowering branch; G. Stem node with bases of two petioles and one stipule; H. Portion of inflorescence with one flower from which corolla has fallen, one flower bud, and one flower at anthesis; I. Cross-section of pyrene and seed. [A: Lowry et al. 4248; B, E: Ralimanana 1209; C–D: Bernard 1675; F: Rakotovao & Randriantatafika 1011; G: Rakotovao 957; H: Daniel 9098; I: Overdorff 39]