Benzoscaphe stelleri Pupulin, Karremans & E. Salas, 2025

Pupulin, Franco, Karremans, Adam P. & Salas Hidalgo, Elvira, 2025, A new nothogenus and nothospecies in the Zygopetalinae (Orchidaceae), with a note on euglossine pollination in the subtribe, PhytoKeys 266, pp. 33-52 : 33-52

× Benzoscaphe stelleri Pupulin, Karremans & E. Salas nothosp. nov.

Type.

Costa Rica • Alajuela: Naranjo, San Juanillo, road to Zarcero , epiphytic in forest remnants at the right of the road, 10°08'40.4"N, 84°23'13.0"W, 1450 m, 14 March 2024, F. Pupulin 9146 & N. Steller ( holotype, JBL-K 0409 ). (Figs 3 – 5 ) .

Diagnosis.

Nothospecies nova caracteribus intermediis inter Benzingiam reichenbachianam ( Schltr.) Dressler et valde probabiliter Chondroscaphen bicolorem (Rolfe) Dressler dignoscenda. Folia viridi-grisacea sicut Benzingiae reichenbachianae sed erecta prod pendulis sicut Chondroscaphe bicolor ; sepalis lateralibus omnino reflexis subuncinatis, basi petalorum ad columna adnata, pede columnae elongato Benzingiae similiter; inflorescentia suberecta prod pendula, petalis subtrapezoideis, labello callis duobus ornato, anthera elongata anguste ovata, polliniis elongatis valde curvatis supra stipitem rectangulo concavo-convexo viscidioque incrassato sicut Chondroscaphe bicolor ; floris magnitudo et forma labelli intermediis inter duabus speciebus.

Description.

Epiphytic, caespitose, erect herbs with a tuft of 4–5 leaves arranged like a fan. Roots flexuous, slender, ca. 1 mm in diameter, whitish, the apex green. Leaves narrowly elliptic, acuminate, 8.0–20.0 × 1.0– 1.8 cm, with a short conduplicate petiole to 0.5 cm long, grayish green, paler on the underside, articulated with basal, ovate, strongly conduplicate sheaths 1.4–3.0 cm long, the margins scabrous-hyaline. Inflorescence a single-flowered raceme, suberect, to 5 cm long; peduncle terete, slender, ca. 3 cm long. Floral bracts two, the outer bract larger, broadly ovate, loose, 7 × 6 mm, the inner bractlet lanceolate, smaller, 7 × 2 mm. Pedicellate ovary terete-subclavate, gently curved toward the apex, 2 cm long. Flower spreading, downward facing, the sepals and petals creamy white, the petals marked with few, scattered rose-purple spots near the base, the lip white, flushed pale yellow toward the base, with lines of purple spots (nectar guides) running from the base to about two-thirds of the blade, the callus on the disc yellow, the column white, sparsely dotted with purple-red at the base, the anther cap cream to light brown. Dorsal sepal lanceolate, acute, 15 × 7 mm, porrect-recurved. Lateral sepals narrowly lanceolate, acute, abruptly apiculate, 25 × 5 mm, strongly reflexed, subuncinate at apex, the labellar margin enrolled from the base to the middle. Petals inserted along the basal side of the column, obliquely obovate to narrowly subrhombic, truncate, 22 × 8 mm, porrect, the apex gently recurved. Lip obscurely three-lobed, 28 × 21 mm, the lateral lobes elliptic, erect to flank the column, the midlobe broadly ovate-trapezoid, apically bilobed, geniculate-bent, apically shortly reflexed, with ruffled margins; disc with a median, irregularly dentate callus, slightly elevated callus in the middle of laminate, and a second thickening toward the apex of the midlobe. Column hemiterete, ca. 10 mm long, dilated around the stigma into elliptic-subtriangular wings, 5 mm wide at the broadest point, provided with a long foot ca 10 mm long, the stigma transversal, slit-like, the rostellum acicular, flanked by 2 pararostellar teeth, the clinandrium low-cuspidate, swallow. Anther cap ovate, apically refuse, 2 - celled. Pollinia 4, narrowly ovate, complanate, in two superposed pairs of different sizes, on a short, rectangular, erected stipe and a narrowly lanceolate, thick viscidium.

Distribution.

Only known from central Costa Rica, where it has been so far documented only from about 1500 meters of elevation along the southeastern slopes of the Central Volcanic Cordillera, facing the Central Valley (Fig. 6 ).

Habitat and phenology.

The nothospecies inhabits the premontane wet forests of the geologically recent Central Volcanic Cordillera in Costa Rica, where it has been exclusively found along the slopes of the range facing south, a region mostly influenced by the Pacific climate. Flowers are produced at least in February and March, at the beginning of the dry season in Costa Rica.

Eponymy.

Dedicated to Norman Steller, of Naranjo, Costa Rica, who participated in the collection of the plant that served as type.

The plant and flower of Benzoscaphe stelleri appear to have no morphologically similar taxa in Costa Rica. Both vegetatively and in terms of floral morphology, its characteristics appear to be intermediate between those of Benzingia reichenbachiana and (most likely) Chondroscaphe bicolor . The leaves of the nothospecies are grayish-green in color, with a prismatic-appearing epidermis, as in B. reichenbachiana , but they are erect and not wavy, as in the genus Chondroscaphe . As for the flower, the lateral sepals are completely reflexed and subuncinate at the apex (rather than spreading), the base of the petals is completely adnate to the column, and the latter has an elongate foot, as in Benzingia (short in Chondroscaphe ). On the contrary, the suberect (rather than pendulous) inflorescence, the subtrapezoid petals, the labellum adorned with two rows of calli (only one central in Benzingia ), the elongated and narrowly ovate anther, and the elongated and strongly curved pollinia, affixed to a concave-convex rectangular stipe and an enlarged viscidium, are similar to those of Chondroscaphe . The size of the flowers and the general shape of the labellum are intermediate between those of the two species.

We do not have conclusive evidence on the pollination of Benzingia Dodson species, but Gerlach and Schill (1991) suggest B. palorae (Dodson & Hirtz) Dressler (as Stenia Lindl. ) is pollinated by male Euglossini bees, while Heide-Jørgensen (2021) reports that in the forests of the Ecuadorian Amazon B. caudata (Ackerman) Dressler (as Chondrorhynhca Lindl.) is pollinated by Euglossa sp. , which receives the pollinarium on the head. Ramírez et al. (2002) reported, based on a personal observation by Robert Dressler, pollination of B. reichenbachiana (Schltr.) Dressler by Euglossa heterosticta , a relatively small bee ca. 1 cm long, but the authors gave no further details regarding the interaction between flower and insect and the place of pollinarium deposition. The same observation is reported by Lipińska and Barabasz (2024) in their review of pollination in Guatemalan orchids. The specific form of the pollinarium and its position on the insect’s body play a key role in effective fertilization of the flower and allow pollen deposition to be species-specific even among closely related taxa. Given the precise and highly specific size and shape of pollinarium and those of the foraging insects, as well as the ability of the flower to manipulate the insect’s behavior to place it in the correct position to receive and deposit the pollen, the margins for mechanical errors, possibly leading to pollination between different taxa, are limited. For example, within the subtribe Zygopetalinae , to which the species in this study belong, Nunes et al. (2017) demonstrated how in Warrea Lindl. and Zygopetalum the bee removes the pollinarium when getting out of the cavity formed by the lip and the column. In Warrea , however, the pollinarium is deposited on the thorax of Bombus brasiliensis , while in Zygopetalum maxillare G. Lodd. and Z. crinitum G. Lodd. it adheres to the back of the head and the head front, respectively, of the carpenter bees that visit the flowers.

There are elements in the morphology of the flower and pollinarium of Benzingia that are indicative of their possible general functioning. The flowers of Benzingia reichenbachiana are gullet-shaped, with the labellum spreading in front and the lateral sepals completely back-swept and inrolled, hooked towards the apex, so as to imitate nectaries (Fig. 7 A ). In a similarly shaped flower ( Warscewiczella lipscombiae , Fig. 7 B ), Ackerman (1983) was able to observe several individuals of Eulaema meriana , Euglossa cognata , and E. imperialis extending their tongues into the cavity formed by the sepals in search of nectar. Most of these floral visitors are too small to come into contact with the column that overhangs the labellum, but Ackerman (1983) documented a female of E. meriana that, after extending the tongue into the nectar less nectary, received the pollinarium on the back of its head when backing out. The presence of “ pseudo-nectaries, ” as well as the broad and low laminar callus at the base of the labellum, appears in fact to be designed to allow the insect to advance deeply into the flower in search of a reward. In turn, the relatively large shield-like shape of the viscidium and the tegula that remains raised after removal suggests that the pollinarium is deposited on the head or on the frontal part of the scutellum of the visiting insect.

Nevertheless, it is possible that several similar, albeit different, pollination syndromes exist in Benzingia , as the flowers of B. hirtzii Dodson are non-resupinate (Fig. 8 A ), so that the visiting bee probably receives the pollinarium on the ventrum rather than on the front or the back of the body ( Pupulin 2009). A similar placement on the ventral part of the insect’s body has been hypothesized for two species of Kefersteinia with non-resupinate flowers ( Carnevali et al. 2015; Sierra-Ariza and Harding 2023), while in species with resupinate flowers the pollinarium is deposited at the base of one of the bee’s antennae ( Dressler 1972; Pupulin 2009).

Unfortunately, even though the pollinaria of Chondroscaphe (Dressler) Senghas & G. Gerlach (as Chondrorhyncha Lindl. ) have been found on a male bee, Euglossa asarophora , records of pollination in species belonging to the genus are limited to observations of a single species ( Reynolds 2004). Ackerman (1983) suggested that the pollination syndrome of Chondroscaphe could be similar to that of Warscewiczella (treated as Cochleanthes Raf. ). However, the only species in the genus whose pollination has been documented so far, Chondroscaphe embreei (Dodson & Neudecker) C. Rungius , lacks the tubular or reflexed sepals that deceive pollinators as false nectaries. Instead, these are spreading, as are the fimbriate petals and lip (Fig. 8 B ). The lip is bilobed, with the base parallel to the column to form a gullet, then spreading and flaring in the apical half. In C. embreei , as well as in most species of the genus, the lip is deeply and irregularly fimbriate, but in Chondroscaphe species recorded in Costa Rica, it is only wavy to ruffled, with entire margins ( Pupulin 2005). Chondroscaphe embreei is pollinated by male euglossine bees, Euglossa trinotata , which receive the pollinarium on the right metasoma ( Reynolds 2004). The pollinarium of C. embreei is large, over 7 mm long, with two pairs of unequal pollinia — the adaxial ones linear and the abaxial ones linear – semi-falcate and much longer. They are connected by yellow caudicles to a broadly rhombic, erect stipe, in turn affixed to a comparatively small, obpeltate, hyaline viscidium (Fig. 9 A ). Even though this is the basic structure of Chondroscaphe pollinaria, specific variations occur. In Costa Rica, the pollinaria of C. atrilinguis Dressler (Fig. 9 B ) and C. yamilethiae Pupulin (Fig. 9 C ) are similar to that of C. embreei , but C. bicolor (Rolfe) Dressler has a much smaller, subquadrate stipe and a comparatively small, elliptic viscidium (Fig. 9 D ).

We cannot know which of the two parent species donated the pollen and which was fertilized. However, since the flower visitor of Benzingia reichenbachiana is a small bee, it would hardly be able to deposit the pollen of this species on the stigma of the Chondroscaphe flower, which is located in a much higher position relative to the callus of the labellum. Available information indicates that the flowers of Chondroscaphe endresii have an intense, spicy fragrance, suggesting the presence of compounds such as eugenol, which is the main reason male euglossine bees visit them in search of scents for their courtship ceremonies. The gullet-shaped flower of B. reichenbachiana , with its nectariform lateral sepals, likely also exhibits a deceptive pollination syndrome. It is possible that the inadvertent hybridization of the two species is the result of the simultaneous presence of two different pollination syndromes, in which one insect may have visited one flower for its scent and subsequently the other in search of a food reward.

Figures

Figure 3. × Benzoscaphe stelleri. A. Habit B. Flower C. Dissected perianth; D. Ovary, column, and lip in three-quarters view; E. Column in lateral, three-quarters, and ventral views (emasculated at the right); F. Pollinarium in dorsal, ventral, three-quarters, and lateral views; G. Anther cap. Scale bars: 3 mm (F, G); 5 mm (E); 1 cm (B, D); 3 cm (C); 10 cm (A). Drawn by S. Poltronieri from F. Pupulin 9146 (voucher at JBL-K 0409).

Figure 5. Flower of × Benzoscaphe stelleri, from the plant that served as the holotype. Photograph by F. Pupulin.

Figure 6. Map showing the type locality of × Benzoscaphe stelleri (red circle) and the known distribution ranges in Costa Rica of Chondroscaphe bicolor (light blue) and Benzingia reichenbachiana (lined blue).

Figure 7. Flowers of Zygopetalinae with back-swept and inrolled lateral sepals. A. Benzingia reichenbachiana; B. Warscewiczella lipscombiae. Scale bar: 3 cm. Photographs by F. Pupulin.

Figure 8. Anomalous flowers of Zygopetalinae. A. Benzingia hirtzii, the flower non-resupinate; B. Chondroscaphe embreei, the lateral sepals not back-swept. Photographs by F. Pupulin.

Figure 9. Pollinaria of Chondroscaphe species. A. C. embreei; B. C. atrinlinguis; C. C. yamilethiae; D. C. bicolor. Scale bar: 3 mm (A – D). Photographs by F. Pupulin.