Costus rubineus D.Skinner & Maas, 2023

Maas, Paul J. M., Maas-van de Kamer, Hiltje, Andre, Thiago, Skinner, David, Valderrama, Eugenio & Specht, Chelsea D., 2023, Eighteen new species of Neotropical Costaceae (Zingiberales), PhytoKeys 222, pp. 75-127 : 75

Costus rubineus D.Skinner & Maas sp. nov.

Diagnosis.

Costus rubineus sp. nov. (Fig. 19 ) looks somewhat similar to C. scaber Ruiz & Pav. but differs from that species by a larger calyx (9-15 vs. 3-7 mm), larger bracteole (20-28 vs. 9-12 mm), larger corolla (50-60 vs. 35-40 mm), and a labellum which is distinctly lobulate at the apex vs. entire in C. scaber ; furthermore it is restricted to high elevations whereas C. scaber is mostly a lowland species; C. rubineus also lacks the row of hairs along the adaxial midvein of the lamina, which is so typical for C. scaber .

Type.

Peru, Pasco: Prov. Oxapampa, Gramazú, 1961 m, 17 Mar 2005, Rojas G., Vásquez Chávez & Francis 3574 (holotype L4196133; isotypes HUT, MO-2152325, USM) .

Description.

Herb 0.5-4 m tall. Leaves sheaths 15-30 mm diam; ligule truncate to slightly lobed, 2-7 mm long; petiole 3-8 mm long; sheaths, ligule and petiole densely sericeous to glabrous; lamina narrowly elliptic, 20-37 × 5-13 cm, adaxially glabrous, abaxially rather densely villose to almost glabrous, base obtuse to slightly cordate, apex acuminate (acumen 10-15 mm long) to acute. Inflorescence ovoid, 7-11 × 4-6 cm, terminating a leafy shoot; bracts, bracteole, and calyx rather densely puberulous to glabrous, ovary and capsule densely sericeous. Flowers abaxially oriented; bracts dark ruby red to red, coriaceous, broadly ovate, 3-4 × 2.5-4 cm, apex obtuse, callus 6-10 mm long; bracteole boat-shaped, 20-28 mm long; calyx red to pink, 9-15 mm long, lobes very shallowly triangular, 2-3 mm long; corolla pink to orange, 50-60 mm long, glabrous, lobes narrowly elliptic, 40-50 mm long; labellum yellow, distal part red, lateral lobes rolled inwards and forming a curved tube ca. 10 mm diam, oblong-obovate when spread out, 30-50 × 18-20 mm, 5-lobulate, lobules narrowly ovate-triangular, ca. 4 mm long; stamen yellow, 30-45 × 7-10 mm, not or slightly exceeding the labellum, apex red, irregularly dentate, anther 8-9 mm long Capsule obovoid, ca. 13 mm long.

Distribution.

Peru ( Huánuco, Pasco) (Fig. 22H ).

Habitat and ecology.

In primary or secondary, premontane or montane forests, at elevations of (300-)1400-2200 m. Flowering year-round.

Etymology.

Costus rubineus sp. nov. is named in reference to the Spanish explorer Hipolito Ruiz who visited in August 1780 the place called Chinchao in the Peruvian department of Huánuco. In his journal, he mentioned the collection of a plant he referred to as " Costus ruber ", but his collection was lost in a shipwreck off the coast of Portugal, and this species’ name was never again mentioned in the journal. Since there is already a C. ruber C.Wright ex Griseb. (a synonym of C. pulverulentus C.Presl), we cannot use that name but are using the very apt name of C. rubineus to reflect the beautiful ruby-red colour of the bracts. The first author of this species visited the Chinchao region in 2016 and found at that locality specimen which he believed to be the same species as Ruiz mentioned in his journal ( Skinner 2016).

Paratypes.

Peru. Huánuco: Cordillera Azul, ca. 42.7 km E of Tingo Maria on road to Pucallpa, 5650 ft, 21 Nov 1979, Davidson & Jones 9395 (U). Pasco: Prov. Oxapampa, Distr. Huancabamba, Zona de Amortiguamiento del Parque Nacional Yanachaga-Chemillén, Sector alto tunqui, 1781 m, 10 Dec 2006, Castillo et al. 642 (AMAZ, HUT, L, MO, USM); Prov. Oxapampa, Pichis Valley, new road between Santa Rose de Chivis and Puerto Bermúdez, 300-400 m, 30 Sept. 1982, Foster 8950A (MO); Prov. and Distr. Oxapampa, Carretera Oxapampa-Tsachopem, 1850 m, 15 Nov 2004, Monteagudo Mendoza et al. 7658 (HUT, MO, U, USM); Prov. Oxapampa, Distr. Huancabamba, Carretera hacia Pozuzo-Zona de Amortiguamiento, Parque Nacional Yanachaga-Chemillén, 1390-1630 m, 22 Mar 2005, Ortiz V. et al. 521 (L, MO, USM); Prov. Oxapampa, 5 km SE of Oxapampa, Oswald Müller property, 1850 m, 13-16 Dec 1982, Smith 2946 (MO, U), idem, 24 Dec 1983, Smith 5360 (HUT, MO, U, USM); Distr. Oxapampa, La Suiza, 10 Dec. 2002, 2200 m, Vásquez Martínez & Rojas 27782 (F, HUT, MO, U, USM).

Notes.

Costus rubineus sp. nov. is a species mostly restricted to relatively high elevations (except for Foster 8950A, which was found at 300 m) in the departments of Pasco, San Martín, and Huánuco, Peru. It looks, at first glance, somewhat similar to C. spiralis (Jacq.) Roscoe, but it differs from that species by its abaxially oriented flowers and a very short ligule. The living plants look similar to C. scaber Ruiz & Pav., but that species differs by a much shorter calyx (3-7 mm vs. 9-15 mm long in C. rubineus ) and the presence of a row of erect hairs on the adaxially of the lamina (lacking in C. rubineus ). There are often several flowers at the same time at anthesis, whereas in C. scaber , there is usually just one flower at anthesis.

Figures

Figure 19. Costus rubineus D. Skinner & Maas A plant in habitat near Villa Rica, Pasco, Peru B inflorescence with flowers showing the labellum with characteristic lobulate apex (a) C adaxial leaf midrib showing absence of line of hairs D bract and flower detail from plant in habitat at Alto Churumazu, Pasco, Peru showing the full flower with subtending bract (flower), bract (br), bracteole subtending the capsule (ovary plus calyx) (brl / ca), stigma and style as attached to the young capsule (gyn), petals, single fertile stamen (st) and labellum (lab). Seeds from this plant were collected and cultivated as D. Skinner R 3421 E plant in habitat at 1980 meters near Chinchao, Huanuco, Peru, the original collection site of " C. ruber " as indicated in Ruiz' journal F inflorescence with lower bracts removed and single flower photographed in the wild near Chinchao, Peru. Photos A-F by Dave Skinner.

Figure 22. Distribution maps for new species of Costaceae. Costus gibbosus - Costus whiskeycola m A Costus gibbosus D. Skinner & Maas B Costus mollissimus Maas & H. Maas C Costus obscurus D. Skinner & Maas D Costus oreophilus Maas & D. Skinner E Costus pitalito C. D. Specht & H. Maas F Costus prancei Maas & H. Maas G Costus pseudospiralis Maas & H. Maas H Costus rubineus D. Skinner & Maas I Costus whiskeycola Maas & H. Maas.