Artabotrys insurae J.Chen & Eiadthong, 2020

Chen, Junhao & Eiadthong, Wichan, 2020, New species and new records of Artabotrys (Annonaceae) from peninsular Thailand, PhytoKeys 151, pp. 67-81 : 67

Artabotrys insurae J.Chen & Eiadthong sp. nov. Fig. 3 , 4A-C

Diagnosis.

Distinct from other Artabotrys species in Thailand in having oblique leaf base and erect-pubescent lower leaf surface. Similar to A. uniflorus Craib (Fig. 4D-F ) but with oblique (vs. rounded or rarely cuneate) leaf base, flat (vs. three-angled) petal blades, apiculate (vs. truncate) anther connective apex and short-stipitate (vs. sessile) monocarps that are weakly beaked (beak ca. 1 mm long vs. 2-5 mm long).

Type.

Peninsular Thailand. Surat Thani Province: Vibhavadi District, Khlong Yan Wildlife Sanctuary, trail from headquarters, ca. 200 m elev., 31 August 2002, D.J. Middleton et al. 1487 (holotype: BKF [SN 142020]; isotype: A).

Description.

Climbers, to ca. 5 m tall. Twigs drying light brown to greyish black, sparsely to densely erect-pubescent, becoming glabrous, epidermis non-flaky. Leaf laminas 9-19 cm long, 3.7-7.5 cm wide, oblong-elliptic to oblong-obovate, chartaceous, glabrous above except the sparsely erect-pubescent midrib and secondary veins, sparsely to densely erect-pubescent below; base oblique; apex caudate to acuminate, acumen up to 15 mm long; midrib sunken above, prominent below; secondary veins 8-13 per side, sunken to flush above, raised below; tertiary venation reticulate, visible on both surfaces; petiole 3-10 mm long, 1-1.5 mm in diameter, erect-pubescent. Inflorescences 1-flowered (rarely 2-flowered), peduncles recurved (often laterally compressed and hook-like), sparsely erect-pubescent, lateral branches condensed, pedicels 5-15 mm long, ca. 1 mm in diameter, sparsely to densely erect-pubescent. Sepals 3, free, valvate, 6-10 mm long, 5-6 mm wide, ovate, sparsely puberulent inside, densely puberulent outside, apex acute, green in vivo. Petals 6, free, valvate, sparsely to densely puberulent on both surfaces except the glabrous base inside, chartaceous, yellow in vivo, blade flat, base concave. Outer petals 3, 17-29 mm long, claw 6-8 mm wide, blade 6-12 mm wide, oblong-ovate, apex acute. Inner petals 3, 16-28 mm long, claw 4-6 mm wide, blade 3-6 mm wide, oblong-elliptic, apex acute. Stamens 20-30, ca. 2 mm long, ca. 1 mm wide, oblong, anther connective apex apiculate. Carpels 10-14, ovary ca. 3 mm long, ca. 0.5 mm wide, stigma ca. 2 mm long, cylindrical. Fruit of up to 10 monocarps borne on a subglabrous pedicel 8.5-20 mm long, 2-2.5 mm in diameter. Monocarps 23-27 mm long, 10-13 mm wide, ellipsoid, smooth, glabrous, apex weakly beaked (ca. 1 mm long), base contracted into a stipe 1.5-4 mm long, green in vivo, drying brownish black, pericarp ca. 2 mm thick. Seeds 15.5-17.8 mm long, 9.4-10.7 mm wide, 4.6-5.2 mm thick, generally smooth with wrinkled area on sides, light yellowish brown.

Phenology.

Flowering and fruiting specimens collected in August and September. Fruiting specimens also collected in February and June.

Distribution and habitat.

So far only known from peninsular Thailand (Fig. 6 ). It occurs in lowland moist and dry forests, secondary forests and forest edges at elevation 80-200 m.

Etymology.

The specific epithet was given in honour of Mr Tawee Insura, whose prolific collection of Artabotrys specimens during his MSc study led to the discovery of several new species and new records for Thailand.

Preliminary conservation status.

Artabotrys insurae is estimated to have an EOO of 15,994 km2 and an AOO of 20 km2. This species largely occurs within various Wildlife Sanctuaries, which constitute Protected Areas in Thailand. A population exists in a remnant forest adjacent to Khao Le Buddhist Temple in Songkhla; such vegetation is regarded as sacrosanct and hence would likely remain undisturbed. We suggest a status of Vulnerable [VU D2] for this species because its restricted AOO makes it susceptible to future threats such as climate change.

Additional specimens examined.

Peninsular Thailand. Narathiwat Province: Sukhirin District, Hala-Bala Wildlife Sanctuary, 7 September 2006, T. Insura 75 (BK, BKF). Songkhla Province: Hat Yai District, Ton Nga Chang Wildlife Sanctuary, Puangpen et al. N192 (QBG); idem, Ton Nga Chang Waterfall, 150 m elev., 2 February 1997, C. Leeratiwong s.n. (PSU); idem, 80 m elev., 12 August 2006, T. Insura 58 (BK, BKF); Sadao District, Khao Le, 150 m elev., 16 August 2018, C. Leeratiwong 18-1522 (PSU); Sadao District, Ton Nga Chang Wildlife Sanctuary, Pha Dam Ranger Station, 350 m elev., 2 June 2017, C. Leeratiwong 17-1116 (PSU).

Notes.

This species is most similar to A. uniflorus from peninsular Thailand (Chumphon, Ranong, Phang-Nga and Surat Thani) in having erect-pubescent lower leaf surfaces, 1-flowered (rarely 2-flowered) inflorescences, caudate to acuminate leaf apex and relatively narrow monocarps (10-15 mm wide). Its distribution overlaps with A. uniflorus in Surat Thani. Artabotrys siamensis Miq. from Northern, Northeastern, Eastern and Southwestern Thailand is also similar in having erect-pubescent lower leaf surfaces, but is distinct due to its coriaceous leaves, cuneate leaf base, thicker petals, numerous carpels (25-29 per flower), numerous monocarps (up to 22 per fruit) and broader monocarps (15-20 mm wide).

Figures

Figure 3. Artabotrys insurae sp. nov. A habit and leaves, showing caudate to acuminate leaf apex (C. Leeratiwong 18 - 1522) B oblique leaf base and inflorescence with hooked peduncle (C. Leeratiwong 18 - 1522) C flower, showing oblong-ovate outer petals and oblong-elliptic inner petals (C. Leeratiwong 18 - 1522) D fruit (C. Leeratiwong 17 - 1116). Photos: C. Leeratiwong.

Figure 4. A-C Artabotrys insurae sp. nov. A habit (T. Insura 58) B flower, showing flat petal blades (T. Insura 58) C fruit, showing weakly beaked monocarps with distinct stipes (D. J. Middleton et al. 1487) D-F Artabotrys uniflorus D habit E flower, showing three-angled petal blades F fruit, showing strongly beaked monocarps that are sessile. Photos: A, B T. Insura C D. M. Johnson D-F P. Chalermglin.

Figure 6. Distributions of A. crassifolius, A. insurae, A. longipetalus and A. pleurocarpus in peninsular Thailand. Only the region in peninsular Thailand is shown; adjacent areas in Peninsular Malaysia and Myanmar are removed.