Mezoneuron scortechinii, F. Mueller, 1882

Clark, Ruth P., 2016, A Taxonomic Revision of Mezoneuron (Leguminosae: Caesalpinioideae: Caesalpinieae), Phytotaxa 274 (1), pp. 448-450 : 448-450

16. Mezoneuron scortechinii F. v. Mueller

South. Sc. Rec.: 73. 1882.

Lectotype:— AUSTRALIA: Queensland, Wide Bay, Bidwill s.n., K (K000264178!), Hattink 1974.

Remaining syntypes:— AUSTRALIA: Queensland, Logan R., 1881, B. Scortechini 166, MEL (3 sheets), NSW; Burnett R., Qld, F.Mueller s.n. (location of specimen unknown) .

Synonym. Mezoneuron traceyi Pedley syn. nov.

Type:— AUSTRALIA: Queensland, Cook District, Kuranda , 16 49 S, 145 38 E, 7 Nov. 1958, L.S. Smith 10448. Holotype BRI (BRI-AQ0010072, image!); isotypes K (K000789366!), L (L0651494!)

Basionym. Caesalpinia traceyi Pedley. Austrobaileya 5: 99. 1997.

Woody climber or scandent shrub to 7 m in length. Stems sometimes with recurved prickles to 3 mm, corky spine-tipped tubercles or longitudinal ridges on older stems; sparsely orange tomentose, glabrescent. Stipules persistent, triangular, black, 0.5–2 × 0.5–2 mm, sparsely orange tomentose, glabrescent. Leaves alternate, with 4–9 pairs pinnae; (4–) 5–9 pairs leaflets per pinna; petiole 1.5–7.5 cm; leaf rhachis (8.5–) 11–25 (–33) cm, with paired recurved prickles at pinna insertion points, and usually scattered on the internodes, including terminal prickle, to 4 mm; pinnae opposite to subopposite, 4.5–9.5 (–11) cm, pinna rhachis sometimes with scattered recurved prickles, including a terminal prickle 1–2 mm; leaf rhachis, petiole, and pinna rhachis sparsely to moderately whitish to orange tomentose. Leaflets alternate to subopposite; the terminal leaflets oblong to elliptic to slightly obovate, base oblique, apex rounded to retuse, mucronulate 1.4–3 (–3.5) × 0.7–1.7 (–2) cm; lateral leaflets oblong to elliptic, base oblique, apex rounded to retuse, mucronulate, 1.1–2.7 (–3.6) × 0.5–1.5 (–2.2) cm; all leaflets with upper surface glabrous or sparsely whitish to orange subappressed hairy, denser at base of blade around midvein, lower surface sparsely, regularly, whitish to orange appressed pilose, the hairs denser at base of midvein, occasionally subglabrous; 2˚ venation anastomosing, 3˚ venation reticulate, 2˚ veins slightly or not visible above, slightly or clearly visible below. Inflorescence a panicle, often large and complex, occasionally a raceme, axillary or terminal, to 40 cm, the racemes alternate; sometimes with recurved prickles to 2 mm on lower part of racemes, peduncle and racemes sparsely to moderately orange tomentose; pedicels 2–7 mm, elongating in fruit to 13 mm, articulated 1–2 mm below hypanthium; sparsely to moderately pale orange to golden tomentose, hair denser around articulation, glabrescent in fruit. Bracts persistent, minute, triangular, ca. 1–1.5 × 1 mm, sparsely to densely orange tomentose on both surfaces, or at margins; bracteoles semi-persistent, lanceolate, narrowing at base, tapering to acuminate apex, (2–) 3–6 × 1–2 mm, sparsely to moderately orange or golden tomentose to pilose on both surfaces. Flowers: sometimes a few male flowers per inflorescence; hypanthium 1–3 × ca. 3–4 mm; sparsely to moderately pale orange to golden pilose, the hair often paler than on peduncle; lower calyx lobe 5–8 × 2–3 mm; other lobes 3–6 × 1–3 mm; all calyx lobes sparsely pale orange to golden pilose to tomentose, hairs covering the lower lobe and on

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A TAXONOMIC REVISION OF MEZONEURON

Phytotaxa 274 (1) © 2016 Magnolia Press • 31 lower parts of other lobes, sometimes denser on margins of lobes. Median petal 5–8 × 2–5 mm, inrolled, with dense circular patch of orange or brown hairs between claw and blade, sometimes long orange tomentose hairs on outer surface of claw. Upper lateral petals 4–8 × 1.5–6, long orange tomentose on inner claw. Lower lateral petals 4–9 × 1–4, long orange tomentose on inner claw. Stamen filaments flattened, 7–12 mm long, densely long orange tomentose on the basal ⅓ to ½ of length, on inner surface; anthers ca. 1 mm. Ovary ca. 2 mm long, glabrous in Australia, densely orange hirsute in New Guinea; style 7–11 mm long, glabrous or sparsely hirsute along lower part of length; stigma funnel-shaped, 0.5–0.75 mm wide, the rim papillate. Fruit coriaceous, suborbicular, the base oblique, the wing very narrow at base, apex beaked; 3–5 × 2.4–3.4 (–4) cm, wing 3–8 mm wide; fruit surface glabrous; venation reticulate, clearly visible on body of fruit, not visible on wing; dark brown; hypanthium semi-persistent; fruit when old breaking up, the wing detaching from fruit body, and the valves separating. Seeds 1 per fruit; elliptic, ca. 1.5–2 × 1.5 cm, not visible in outline on fruit exterior, pale green to brown, smooth. ( Fig. 18 )

Distribution:— Papua New Guinea, Australia. ( Fig. 19 ).

Habitat and ecology:—Rainforest; secondary forest; scrub.

Phenology:— Papua New Guinea: flowering September, fruiting time unknown. Australia: flowering time May–December, fruiting May–March.

Preliminary conservation assessment:—Extent of Occurrence 969,996.884 km 2 = LC; Area of Occupancy 252.000 km 2 = EN.

Category assigned:—Least Concern (LC).

Taxonomic notes:—The principal differences between C. traceyi as described in the protologue, and M. scortechinii , are the slightly more numerous leaflets (9–12 pairs vs. 5–9 pairs), slightly more numerous pinnae (7–11 pairs vs. 4–9 pairs), and smaller flowers (3.5–4.5 mm vs. 4–8 mm). However, the ranges of variation between the supposed species are contiguous or overlapping for each character. Additionally, the inrolled claw of the median petal of C. traceyi described in the protologue and indicated by Pedley (1997) as being a distinctive character for that proposed species is a character of M. scortechinii and does not distinguish C. traceyi . The morphological evidence overall does not support the existence of two distinct species. Moreover, the range of the specimens formerly named as C. traceyi falls within the range of M. scortechinii , and no ecological difference is known that would define two entities. Therefore, C. traceyi is here placed into synonymy with M. scortechinii .

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Figures

FIGURE 18. Illustration of M. scortechinii (drawn by Eleanor Catherine).

FIGURE 19. Distribution of M. scortechinii in New Guinea and Australia.