Compsoneura nallarettiana M.Ríos, R.Zárate & J.Grandez, 2023

Ríos Paredes, Marcos A., Zárate-Gómez, Ricardo & Grandez-Rios, Julio Miguel, 2023, Compsoneura nallarettiana (Myristicaceae), a new species from north-western Peru, Phytotaxa 592 (3), pp. 294-300 : 294-297

Compsoneura nallarettiana M.Ríos, R.Zárate & J.Grandez , sp. nov. ( Fig. 1 )

Type:— PERU. San Martín: Área de Conservación Regional Cordillera Escalera , km 20 carretera Tarapoto-Yurimaguas , Centro Académico , Investigación y Ecoturismo “Biodiversidad”, a 7.4 km al SSW de Tarapoto, bosque de tierra firme. 734 m, -6.469775, -76.2951175, 19 May 2017, Flores & Vásquez 803 (holotype: HH!; isotype: HOXA!) .

The new species is similar to C. diazii but differs from the latter in its weakly brochidodromous secondary veins with leaf apex acuminate to brevi-acuminate and sessile fruit vs. brochidodromous secondary veins, an acute to caudate apex and pedunculate fruit.

Dioecious trees 10–25 m tall, 10–43 cm dbh, the inner bark exuding profuse reddish sap, branchlets terete to subterete, 0.19–0.33 cm diameter, rigid, longitudinally striate, drying dark brown. Leaves simple, alternate, distichous, petiole subterete, canaliculate, 0.70–1.60 X 0.10–0.22 cm, rugose, drying dark brown; blades elliptic to obovate-elliptic, 7–16 X 3–6 cm, adaxially drying dark brown, glossy to semi-glossy, glabrous, sometimes with black dots (observed at 30 X magnification), abaxially drying dull brown, glabrous, sometimes with black dots, base acute to attenuate or subobtuse, margins revolute, apex acuminate to brevi-acuminate, acumen 0.43–1.91 cm long; middle vein emergent, glabrous adaxially, brochidodromous secondary veins weak, 4–13 per side, arcuate-ascending, anastomosing near margins, shallowly impressed adaxially, prominent abaxially, 0.8–2.5 cm apart, tertiary veins conspicuous, semiparallel to the middle vein and secondary veins. Staminate inflorescences axillary, 1–3 fasciculate, once-paniculate, (5.5–) 6.5– 10.4 X (2.0–) 3.0–5.5 (–7.3) cm, densely ferrugineous-tomentose, the hairs 2-branched; rachis alternately branched, the branchlets 8–24, the flowers arranged in clusters of about 2–8 per branchlet; pedicels slender, pubescent, (0.063–) 0.100 –0.130 X 0.035 –0.050 cm. Pistillate inflorescences axillary, once-paniculate, 0.7–0.8 X 0.8–0.9 cm, densely ferrugineous-tomentose, sericeous or both, hairs 2-branched; rachis with 7–11 alternate branches, flowers subsessile and arranged in clusters of about 1–2 (–4) per inflorescence branchlet; pedicels slender, pubescent, 0.10–0.13 X 0.05– 0.10 cm. Staminate flower buds orbicular to ovate or oval, 0.11–0.17 X 0.09–0.16 cm. Pistillate flower buds orbicular to oval, 0.20–0.23 X 0.14–0.22 cm. Perianth of staminate flowers short-tubular, 0.12–0.18 X 0.09–0.17 cm, drying brown to dark brown with golden indument, thinly pubescent adaxially, glabrescent to ferrugineous-tomentellous to tomentose abaxially, the hairs short-stalked to sessile, 2-branched, the tube 0.028 –0.088 cm long, the lobes (2–) 3–4 (–6), narrowly ovate to lanceolate-ovate to narrowly deltoid with acute apex, 0.07–0.12 cm X 0.06–0.13 cm wide at base; androecium 0.05–0.12 cm long, the filament of 0.019 –0.052 X 0.012 –0.032 cm, the anthers 4–6 (–7), subequal to the androphore, free, recurved, 0.03–0.08 cm long. Perianth of pistillate flowers subsessile, ovate to elongate-ovate, 0.20–0.23 X 0.14–0.22 cm, drying brown to dark brown, thinly pubescent adaxially, densely to sparsely ferrugineous-tomentellous to ferrugineous-tomentose abaxially, the hairs 2-branched, the tube 0.09–0.12 cm long, the lobes 3 (4), ovate, 0.10–0.11 X 0.11–0.14 cm; ovary ovate with acute apex, 0.08–0.15 x 0.04–0.11 cm, drying brown, densely ferrugineous-tomentose with golden indument; stigma bilobate, brown to dark brown when dry. Immature fruits sessile with 1 to 4 per infructescence, ovate, 28–30 X 21–23 mm, sulcate, light brown when fresh and ferrugineous-tomentose, apex minutely acuminate, base truncate, mature fruits not observed.

Distribution and ecology:— Sandy substrates in terra firme forests, 500–1300 m, Department of San Martin in north-western Peru ( Fig. 2 ).

Phenology:— Flowering in May, fruiting in August.

Etymology:— Dedicated to Nállarett Marina Dávila Cardozo, known to her friends as Gigi in recognition of her commitment to the study and conservation of tropical biodiversity in Peru, Brazil, Colombia, Ecuador and Venezuela, which will be an inspiration to coming generations.

Conservation status:— Following the IUCN Red List Criteria ( IUCN 2022), this new species is proposed as critically endangered (CR). The extent of occurrence (EOO) is calculated to be 27 km 2 (criterion B1 <100 km 2, critically endangered) and the area of occupancy (AOO), 24 km 2 (criterion B2 <500 km 2, endangered). This species is partially protected because the population lies within in the Cordillera Escalera Regional Conservation Area.

Additional specimens examined:— PERU. San Martin : San Martin, Banda de Shilcayo, Centro Académico, Investigación y Ecoturismo Biodiversidad , -6.469775, -76.2951175, 734 m. a.s.l., 19 May 2017, Flores & Vásquez 533, 539, 652, 699, 781, 803, 843, 987, 994, 1000, 1024, 1073 (HH!) ; San Martin, San Antonio de Cumbaza, Canela Ishpa , -6.3879, -76.4089, 953 m. a.s.l., 3 Aug 2013, Mori et al. 2009 (HH!) .

Notes:— Compsoneura nallarettiana differs from other Compsoneura species in its sessile fruits. With respect to leaves, C. nallarettiana resembles C. cuatrecasasii Smith (1950: 318) , C. debilis , C. diazii Janovec , C. excelsa Smith (1938: 413) and C. mutisii Smith (1938: 415) , but it can be differentiated by the size of male flowers and inflorescences ( Table 1 ). Compsoneura diazii and C. nallarettiana occur in the Amazon Basin, north-western Peru, with C. diazii as far as southern Ecuador, whereas the remaining taxa are reported from Brazil, Colombia, Costa Rica, Venezuela and northern Ecuador. Campsoneura nallarettiana is differentiated from C. diazii by the former having weak brochidodromous secondary veins and an acuminate to brevi-acuminate apex, whereas C. diazii has brochidodromous secondary veins and an acute, caudate apex. Campsoneura excelsa and C. nallarettiana have inflorescences from 5.5 to 10.4 cm long, whereas the other species have up to 4.5 cm inflorescence. Furthermore, these species have distinct geography, with C. excelsa found only in Costa Rica and C. nallarettiana only in Peru ( Table 1 ).

For a better understanding of the diversity in this genus, we recommend further investigation of species distributions and biogeography. For some species, including C. debilis , C. lapidiflora Jaramillo & Balslev (2002: 561) , C. trianae and C. ulei Warburg in Pilger (1905: 136), additional work is also needed on characteristics of female flowers and fruits.

Figures

FIGURE 1. Compsoneura nallarettiana. A. Habit with axillary staminate inflorescence. B. Axillary pistillate inflorescence. C. Pistillate flower with ovary. D. Staminate flower with androecium. E. Staminate inflorescence. F. Immature fruit.

FIGURE 2. Distribution of Compsoneura nallarettiana in north-western Peru.