Hoya krusenstierniana Simonsson & Rodda subsp. laticorolla Simonsson & Rodda, 2022

Rodda, M. & Simonsson, N., 2022, Contribution to a revision of Hoya (Apocynaceae: Asclepiadoideae) of Papuasia. Part II: eight new species, one new subspecies, Blumea 67 (2), pp. 139-155 : 145

Hoya krusenstierniana Simonsson & Rodda subsp. laticorolla Simonsson & Rodda , subsp. nov. — Fig. 5, 6

Similar to Hoya krusenstierniana Simonsson & Rodda subsp. krusenstierniana in its pink,purple to crimson rotate to campanulate corollas,but differing in the size of the corolla (c. 20 mm in subsp. krusenstierniana vs 27–30 mm in subsp. laticorolla ), and the corpusculum (c. 310 by 170 µm in subsp. krusenstierniana vs 500–600 by 350–400 µm in subsp. laticorolla ). — Type: NGF ( E. E. Henty, D. B. Foreman, M. Galore) 42752 (holo L [ L0834584 ]; iso LAE), Papua New Guinea, Western District , Kiunga Subdistrict , Hong Kong Hill, Ok Tedi headwaters, 6900 ft ( 2103 m), 28 Oct. 1969 .

Etymology. Named for its larger corollas compared with Hoya krusenstierniana subsp. krusenstierniana .

Climber, epiphytic, latex colour unknown. Stems cylindrical, slender, 1–2 mm diam, internodes (1–) 4–12 cm long, pubescent to glabrescent. Roots not observed. Leaves: petiole terete, channelled above, 5–8 by c. 1 mm, pubescent to glabrescent; lamina elliptic, coriaceous, 20– 50 by 6 – 20 mm, apex acuminate, base attenuate, margin recurved, glabrous; venation pinnate, midrib depressed on adaxial surface, secondary veins 3–7 each side. Basal colleters 1 or 2, ovate, 0.2–0.3 mm long. Inflorescence one per node,positively geotropic,pseudo-umbelliform, consisting of 1–5 flowers; peduncle extra-axillary, terete, 2–3.5 cm by 0.5–0.7 mm, older peduncles forming a rachis from previous flowerings, pubescent; pedicels filiform, 23–28 by c. 0.4 mm, glabrous. Flowers pink, purple to crimson. Calyx 4–5 mm diam; lobes broadly elliptic, 1.5–2 by 1–1.5 mm, apex rounded, glabrous. Basal colleters one at each calyx lobe sinus, ovate, 0.5–0.7 mm long. Corolla rotate or shallowly campanulate, 27–30 mm diam when flattened; tube c. 6 mm long, outside glabrous, inside pubescent; lobes deltate, 9–11 by 8–10 mm, apex acute, outside glabrous, inside pubescent. Corona staminal, 1.5–2 mm high, 6–6.5 mm diam; lobes with basal process, rhomboid, 2–2.5 by 2.2–2.4 mm, outer apex slightly bilobed, with basal revolute margins; inner process oblong, c. 3 by 1.5 mm; outer process ovate, slightly raised, spreading, apex rounded. Pollinia oblong, 600 –700 by 250 – 300 µm, apex truncate, base rounded, with pellucid margin; corpusculum rhomboid, 500–600 by 350–400 µm; caudicles attached towards the middle of the corpusculum, 150–200 µm long. Ovary semiglobose, c. 0.5 by 1 mm, glabrous. Fruit and seed not observed.

Distribution — KnownfromtwolocationsinPapuaNewGuinea, one of which was communicated to us as ‘Mt. Mini’ (Stephanus Venter, pers. comm.), which we have been unable to locate.

Habitat & Ecology — Growing high up in the mountains at 2000 m above sea level or more, it grows in the same habitat as H. krusenstierniana subsp. krusenstierniana . Based on recent observations by Stephanus Venter it was found in scrub with scattered trees, mainly Podocarpaceae , on peat soil.

Conservation status — Data Deficient ( DD; IUCN 2012 ). The only vouchered collection is the type specimen collected 53 years ago, and the recent sighting at ‘ Mt. Mini’ .

Note — The two subspecies of H. krusenstierniana have the highest altitudinal record for Hoya in Malesia, as they grow at 1800–2600 m. The corona morphology of H. krusenstierniana subsp. krusenstierniana is quite variable ( Simonsson Juhonewe & Rodda 2017: f. 16, 17) and therefore unlikely to be a good character for taxon separation, even though it appears that the centre of the corona of H. krusenstierniana subsp. laticorolla is more conical compared with specimens of H. krusenstierniana subsp. krusenstierniana . This feature is, however, often obliterated in herbarium specimens.As mentioned in the diagnosis, the reliable characters to separate the two subspecies lie in the corolla and corpusculum size. Since the two taxa occupy the same type of habitat and their morphological variation is still not well known we decided to consider the new taxon a subspecies of H. krusenstierniana rather than a new species.