Cyrtandra tempestii Horne ex Clarke (1883: 273)

Johnson, Melissa A., 2020, Revision of Cyrtandra tempestii (Gesneriaceae) and the description of Cyrtandra tuiwawai from Taveuni, Fiji, Phytotaxa 429 (4), pp. 251-260 : 252-255

Cyrtandra tempestii Horne ex Clarke (1883: 273)

Figs. 1 , 2

Type:— FIJI. Taveuni: In woods near the sea at Salialailai, September 1878, Horne 1136 (holotype K!, isotype GH!).

Diagnosis:— Cyrtandra tempestii is similar to C. rotumaensis St. John (1970: 457) but differs in its longer pedicels (to 20 mm vs. 10 mm), calyces with linear lanceolate lobes (vs. calyces with narrowly ovate lobes with lanceolate tips), and larger corolla (to 20 mm long vs. to 11.5 mm long). It also shares affinities with C. samoensis Gray (1862: 39) , but differs in its smaller leaves (to 43 × 17 cm vs. 91 × 36 cm), longer bracts (4 mm vs. 2 mm), longer pedicels (to 20 mm vs. 12 mm), white calyces with equally cleft linear lanceolate lobes (vs. pale green calyces with unequally cleft lanceolate lobes), and white corolla (vs. corolla greenish yellow to white with yellow coloration at the mouth of the tube).

Description:— Shrub up to 2 m tall; stems unbranched or few branched near the base with appressed brown pubescence. Leaves opposite, borne on upper 2–5 nodes, internodes 2–3 cm long, blades elliptic to elliptic obovate or ovate, 29–43 cm long and 12–17 cm wide, upper surface green and strigillose with univariate multicellular trichomes, lower surface light green, pubescent, 5–7 secondary veins on each side, margins serrulate to crenulate, apex acute to rounded or obtuse, base oblique to aequilateral and cuneate to rounded, petioles 5–7 cm long, pale green with sparse to moderately dense brown pubescence; inflorescence an axillary cyme, 9–17 flowers, cymules 1–3 flowered, peduncle 15–29 mm long, terminated by lanceolate bracts, to 4 mm long, deciduous after anthesis, pedicels 10–20 mm long; calyx pale green to white, outer surface sparsely pilose with brown trichomes, inner surface glabrous, lobes linear lanceolate and equally cleft nearly to the base, 11–13 mm long, deciduous; corolla white, tube funnelform, slightly curved, 18–20 mm long and 6–7 mm wide, outer surface glabrous, inner surface with short glandular trichomes near the mouth of the tube and covering the lobes, upper lobes to 7 mm long and 6 mm wide, lower lobe to 10 mm long and 8 mm wide; stamens 2, filaments white with an orange spot near the base, to 2 mm long, anthers apically connate; staminodes 3, 1–2 mm long, adnate 1–2 mm below filaments and opposite the posterior sinuses; nectary disc annular, cupulate, to 2 mm high, drying to a pelviform structure, persistent in mature fruit; gynoecium (ovary, style, stigma) to 15 mm long, ovary and style glabrous, stigma applanate, bilobed; berries ellipsoid to ovoid, to 16 mm long and 10 mm wide, glabrous, turning white at maturity.

Distribution and ecology:— Cyrtandra tempestii is only known with certainty from a single small population in the coastal forest of Salialailai, southern Taveuni, Fiji ( Fig. 3 ). The individual collected further north at Lavena shares the coastal habitat preference that is characteristic of C. tempestii and also has a similar floral morphology with this species (see Fig. 2D ), but the leaf shape of this individual is more strongly elliptic. Additional molecular work is required (see below) to determine if this lone individual is in fact C. tempestii or if it represents a hybrid ( C. ciliata Seemann (1866: 182) and C. gregoryi Johnson (2017: 87) both grow nearby but have only been observed at elevations above 30 m).

Phenology:— Individuals of this species have been observed to flower and fruit in August and October.

Phylogenetic placement:— Material from the type locality at Salialailai was not available for inclusion in the phylogenetic analysis by Johnson et al. (2017), thus precluding placement of Cyrtandra tempestii . However, the individual collected from Lavena, here referred to as C. aff. tempestii , was placed with strong support (85 BS, 100 PP) in a clade comprised of 13 species from eight geographic regions in the Pacific ( Samoa, Fiji, Vanuatu, Society Islands, Micronesia, Tonga, Wallis & Futuna, and the Loyalty Islands; Fig. 4 ). The closest relatives of this individual remain unknown, as it forms a polytomy with two other clades. Gillett (1967) proposed that C. denhamii Seemann (1866: 182) (endemic to Gau, Fiji) and C. rarotongensis Cheeseman (1901: 290) (endemic to Rarotonga, Cook Islands) were closely related to C. tempestii based on similar habit, leaves, inflorescence, and calyx morphology, as well as the presence of a nectiferous annular disc. St. John (1970) suggested that the closest relative of C. tempestii is C. rotumaensis (endemic to Rotuma, ~ 460 km north of the Fijian archipelago), with its coastal habitat preference and similar leaf morphology. The most notable difference between these two species is the floral morphology, with C. rotumaensis having smaller flowers and narrowly ovate as opposed to linear lanceolate calyx lobes (St. John 1970, J. Game pers. comm.). Unfortunately, C. denhamii , C. rarotongensis and C. rotumaensis have not been included in a phylogenetic analysis to date. Cyrtandra tempestii also appears similar to C. samoensis (endemic to Samoa, Tonga, and Niue) in terms of overall morphology and coastal habitat preference, and C. tuiwawai sp. nov. in terms of calyx morphology. Both C. samoensis and C. tuiwawai are supported as belonging to the larger clade within which C. aff. tempestii is placed.

Conservation status:— Proposed IUCN Red List Category: Critically Endangered (CR) based on an estimated area of occupancy of <500 km 2 (criterion B2), known to exist at no more than five locations (B2a), projected decline in extent of occurrence, area of occupancy (B2bii), and area, extent, and/or quality of habitat (B2biii), and population size estimated to number fewer than 50 individuals (D). Threats to this species include the clearing of coastal forest for agricultural crops, invasive species that can compete for resources (M. Johnson, pers. obs.), and damage caused by high winds and storm surges during tropical cyclones. An indirect effect of agricultural practices in areas where Cyrtranda tempestii occurs is a proliferation of crop pests such as mealybugs ( Pseudococcidae ), which were found in dense populations on the underside of leaves and around the inflorescences of the specimen collected in Lavena ( Fig. 2D ). Mealybug infestation can lead to leaf drop, and the insects can act as vectors for a number of plant diseases. Additional surveys of the coastal forests of Taveuni are warranted to better characterize the distribution and demographics of this species, and will also aid in future conservation assessments.

Additional specimens examined:— FIJI: Taveuni : growing along the Lavena coastal walk, ca. 3 km W of Lavena Village, 17 m elev., 16°52.43’ S, 179°54.14’ W, 03 August 2014, M.A. Johnson 103 with G.J. Hora (RSA!) ; Salialailai , growing at the mouth of a stream in Barringtonia edulis dominant coastal forest, two streams before the Ravilevu Nature Reserve, ~ 2 m elev., 05 October 2017, M. Tuiwawa 5087 and 5088 (SUVA), J.C. Game loc.cit 16°57.23’ S, 179°59.54’ W (WGS84) 17/073 ( UC!) .

Notes:— A single individual with floral affinities to Cyrtranda tempestii was observed on the coast at Lavena ( Fig. 3 ). No other Cyrtandra species were observed in the immediate vicinity, although C. gregoryi was collected 0.64 km to the NW. The population of C. tempestii at Salialailai comprised several individuals, with no other conspecifics observed in the area ( Fig. 3 ).

Figures

FIGURE 1. Cyrtandra tempestii Horne ex C.B.Clarke A Habit B Stem and inflorescences C Corolla, anterior view D Mature fruits. Drawn by Liv-Monique Johnson from field photographs by J. Game.

FIGURE 2. Cyrtandra tempestii Horne ex C.B.Clarke from Salialailai and C. aff. tempestii from Lavena A C. tempestii shrub habit B C. tempestii corolla, anterior view C Lateral view of C. tempestii flower, buds and mature fruit D C. aff. tempestii axillary cyme inflorescence with calyces cleft to base. Photos A–C taken in the field by J. Game, photo D taken in the field by M.A. Johnson.

FIGURE 3. Distribution of Cyrtandra tempestii Horne ex C.B.Clarke and C. tuiwawai M.A.Johnson on Taveuni, Fiji. The location of the single individual referred to as C. aff. tempestii collected from Lavena is also noted.

FIGURE 4. A portion of the Maximum Likelihood phylogram from Johnson et al. (2017) based on three nuclear (ITS, ETS, Cyrt1) and two chloroplast (psbA-trnH, rpl32-trnL) loci. Support values shown for each branch are bootstrap (BS) and posterior probabilities (PP) when ≥ 50% and ≥ 0.50, respectively.An asterisk indicates 100% BS or 1.0 PP; a dash indicates that the branch was not supported.