Hydnophytum grandiflorum Becc.

51. Hydnophytum grandiflorum Becc. View in CoL — Fig. 54 View Fig

Hydnophytum grandiflorum Becc.(1884) 126;(1885) 171,t.44:13–25; Gibbs (1909) 153; Parham (1964) 193; (1972) 271; A.C.Sm. (1988) 242, f. 90: a–b, 129. — Type: Graeffe s.n. (K) Fiji, Ovalau,Mt Tana Lailai,Dec. 1864.

Myrmecodia vitiensis Seem. (1861) 256, nom. nud.; A.Gray (1862b) 36; Seem. (1862) 438. — Type: Seemann 216 (lectotype selected here P; iso BM, CAL, G, GH, K), Fiji, Kandavu, Mt Mbuke Levu.

Hydnophytum longiflorum auct. non A.Gray (1858) : A.Gray (1862a) 318; (1862b) 36; Seem. (1862) 438, p.p.; (1866) 138; Drake (1890) 99, p.p.; Becc. (1885) 172, t. 45: 1–7; Parham (1964) 193, p.p.; (1972) 272.

Squamellaria jebbiana Chomicki in Chomicki & S.S.Renner (2016) 14, f. 2: i, 3: N–P, 9. — Type: G. Chomicki, J.Aroles & A. Naikatini 74 (holo SUVA; iso GH, K, L, M barcode M-0274837, MO, NOU, NSW, P, S), Fiji, Taveuni, Des Voeux peak, 450 m alt., 22 Mar. 2015.

Tuber broadly conical, to 35 by 30 cm, slightly lobed at periphery; surface dark brown, smooth. Entrance holes of two types, conical to 1 cm across, with a prominent rim, or large and funnel-like to 4 cm across. Stems numerous, to 40 by 0.6 cm, branching freely, spreading to upcurved. Internodes to 7 cm when sterile, 0.4–2(–4) cm when fertile, with 2 slight ridges running from below stipules. Leaves clustered, erect to spreading. Lamina elliptic to ovate, 1.6 by 1 to 7 by 3.1 cm; apex rounded to acute; base rounded to truncate, abruptly attenuate; midrib prominent above and below; veins 4–6 pairs; leathery and brittle. Petiole to 0.2 cm; stipules rounded, 0.1–0.3 cm, with a prominent central process to 0.3 cm, continuous with stem ridge, caducous. Inflorescence terminal, becoming axillary, solitary, shortly pedunculate. Bracts c. 1 mm, papery. Flowers [7] heterogamous. Calyx entire, to 2 mm. Disc at or slightly above level of calyx, not prominent in fruit. Corolla tube 15–46 mm long, lobes to 10 by 5.5 mm, elliptic; uncus 1–2 mm; with a ring of hairs at mouth of corolla tube. Anthers exserted from mouth of tube. In female-sterile flowers anthers 2.5–3.5 mm long, containing 4-colpate pollen, 105–130 μm diam, with walls 7.5 μm thick, brochi 8–15 μm across; style to 6 mm, not attached to disc; stigma <1 mm across, above anthers. In male-sterile flowers, anthers 1.2–2.5 mm long, lacking pollen; stigma capitate, broadly 4-lobed, and exserted from corolla mouth, to 3 mm across. Fruit globose to 12 by 9 mm, baccate, pink when ripe. Pyrenes 2 or 3, obovoid-oblong; 5.5 by 2.5 mm; semi-circular to triangular in section, rounded at apex and base.

Ecology & Habitat — Lowland to montane forest,200–1100 m. The tuber appears to be less regularly occupied by ants than H. longiflorum [52], and is often found to be occupied by skinks, geckoes and their eggs, and invertebrates, in particular spiders, myriopods and cockroaches.

Distribution — Fiji (Viti Levu, Ovalau, Kandavu, Vanua Levu and Taveuni).

Conservation status — Near Threatened (NT). This species is found on all 5 of the larger islands in the Fijian archipelago. Other information: georeferenced collections 20, AOO 68 km 2 (using a cell width of 2 km), EOO on Viti Levu alone 1 000 km 2.

Notes — Gray created confusion when he redescribed his 1858 H. longiflorum when specimens of H. grandiflorum came to hand in 1862. Beccari compounded this error and described H. longiflorum purely from Seeman’s description of Myrmecodia vitiensis . Albert Smith unravelled the nomenclature in Flora Vitiensis Nova (1988). The present species is distinguished from H. longiflorum [52] by its larger flowers with pubescent throats, and globose, fleshy fruits. Whilst the tubers of H. grandiflorum tend to be smooth-surfaced, this is not a consistent or reliable identification feature to distinguish it from H. longiflorum (Chomicki & Renner 2016) .

The flowers of both Hydnophytum species in Fiji demonstrate a remarkable form of heterogamy, with staminate and pistillate flowers. This was not understood by Beccari, when working with herbarium material alone. From field observations (by MHPJ) it seems that flowers of both sexes may occur on a single inflorescence, while in other plants only one sex can be found. Smith reports finding hermaphrodite flowers (1988), but we have not seen this. When anthers contain pollen, it seems that their size physically results in the stigma being unable to pass between them, and as the corolla tube elongates, apparently faster than the style can grow, it is presumably plucked from the disc, in effect, a process of female neutering.

The pollen of all Hydnophytinae in Fiji share characteristic pollen. The majority of Hydnophytum spp. have 3-porate (more rarely 3-colpate) pollen 40–70 μm across, with a mean of 52 μm and a punctate surface. Two exceptions are H. magnirubrum [37] and H. minirubrum [38], which have pollen grains up to 100 μm across, with a coarsely reticulate exine with brochi c. 1–5 μm across. The pollen of Fijian Hydnophytinae is 3–5-col-pate, and 70–160 μm diam with a coarse reticulation with brochi 6–15 μm across.

Chomicki & Renner (2016: 14) described a further species of Squamellaria from Taveuni Island, S. jebbiana Chomicki. They acknowledged that the species cannot be morphologically distinguished except for its occurrence on Taveuni Island. The species was taxonomically diagnosed by having a consistently elliptic lamina and a single base substitution in two genes; a C in position 354 of the ITS gene (GenBank # KU586342) instead of an A or T, and a C at position 278 of rps16 (GenBank # KU586438) instead of an A as in all other Fijian Squamellaria specimens (n = 13) examined (Chomicki & Renner 2016).