Kairoa cromeana Takeuchi, 2012

Takeuchi, Wayne, 2012, Floristic records from Momase region, Papua New Guinea, Phytotaxa 52 (1), pp. 54-64 : 54-58

Kairoa cromeana Takeuchi , sp. nov. ( Figs. 1–3 )

Haec species a congeneris omnibus partibus glabris differt (bracteis masculinis minutissimo-puberulis glabrescentibus exceptis).

Type: — PAPUA NEW GUINEA. Morobe Province: Nasau Bay , natural-growth forest on ultrabasics, 7°18'S, 147°08.3'E, sealevel, 22 September 2007, Takeuchi, Ama & Siga 21772 (holotype A!; isotypes LAE!, M!, and 5 undistributed duplicates!) .

Understory shrubs, 2–4 m tall, monoecious, glabrous (or glabrescent). Branchlets apically compressed, 2.5– 4(–6) mm diameter, straight; surfaces longitudinally lined, yellowish green, without lenticels; older axes cylindrical, woody or pithy, occasionally marked by crateriform abscission scars; periderm not fissured nor exfoliating; internodes (2–)3.5–10.5(–13.5) cm long. Leaves opposite, equal, exstipulate; petioles (7–)10–20 × (1–)1.5–2(–3.5) mm, deeply channelled on upper side, rounded beneath, rugulose, proximally articulated or not; leaf-blades firm, elliptic-oblong, (11.8–)15.5–24.7 × (4.3–)6.2–11.2(–13.2) cm; base cuneate to obtuse, equal (or suboblique); margin coarsely serrate-crenate; apex acuminate or broadly rounded; surfaces usually shining, adaxially olivaceous (or brunnescent), often bullate, abaxially ochraceous to yellowish green; venation brochidodromous (on wide blades) or camptodromous (on narrow blades); secondary veins 5–8(–11) per side, (1–) 2.2–5.5 cm apart, at the lamina center diverging 55–85° from the midrib, gradually arcuate, closing (on brochidodromous leaves) by looping nerves (2–)4–15(–19) mm from the margin, anastomosing beyond the loops, with or without 1(–2) inframarginal set(s) of additional commissural nerves parallel to the first; reticulum conspicuous, irregular, tessellate-areolate; midrib bifacially prominent; all higher order nerves distinctly raised on both sides. Staminate inflorescence racemose-subpaniculate (or inserted on basal axes under the pistillate flowers), 4–10(–15) × 5–12(–17) mm when occurring separately, solitary (or 2–3 together); primary (axial) bracts scale-like, ca. 0.5 mm long, puberulent, glabrescent, caducous. Staminate flowers (1–)3–18(–23) per inflorescence, brunnescent to fuliginous; pedicels 4.5–5.5(–8) × 0.3–2.3 mm, gradually flared towards the top, not articulated; bracteoles 0–2, triangular, obscure, ca. 0.1 mm long; receptacle narrowly obovoid, 0.8–1.2 × 1.9–2.3 mm, glabrous on all internal surfaces; tepals 4 in 2 opposing pairs, rotund, 0.2–0.3(–0.4) × 0.6–0.7 mm, imbricate, membranous, eglandular; stamens (measurements from spirit-preserved flowers) 6 in 2 discrete series, columnar, erect; inner stamens 2, 0.5–0.7 × 0.2–0.4 mm; outer stamens 4, similar to the inner series but larger, 1–1.3 × 0.8–1.2 mm; anther cells equal in width to the filaments, dehiscing vertically, stomia confluent across the top; staminodes absent. Pistillate inflorescence axillary, racemose or subpaniculate, (13–)20–40 × (11–) 17–24 mm, solitary (or 2 together), pauciflorous, with or without staminate flowers on basal branches; peduncle (1.5–)5–9(–14) × 0.6–2 mm, compressed, brunnescent; main axes to 28 × 1.2 mm; basal bracts numerous, scale-like, minutely ovate; primary (axial) bracts ovate-deltate, 0.6–0.8 × 0.2–0.3 mm, caducous. Pistillate flowers (1–)3–11 per inflorescence, arranged in unisexual clusters (or inserted above the staminate flowers when both sexes present together), ebracteolate, smooth, dull black; pedicels 5–8.5(–10) × 0.5–3.5 mm at anthesis, 7.5–11 × 0.7–4.5 mm at receptacle abscission, distally expanded, not articulate at the top; receptacle obovoid, (1.5–)2–3 × 3–4 mm, calyptrate, glabrous on all internal surfaces; tepals 4 in 2 opposing pairs, rotund, subequal, ca. 0.2–0.3 × 0.6–0.8 mm (rehydrated measurement); ostiole base biglandular; carpels 26–30, conoid or columnar, 1.1–1.3 × 0.2–0.4 mm, congested, erect, flat on the commissural faces; stigma sessile, globular to button-like, as wide as the carpel. Infructescence of single receptacles from leafy axils; pedicels vasiform, 12–15 × 2–5 mm, distally expanded, not articulate; receptacle ± discoid, 7–11 mm across, accrescent; fruiting monocarps ellipsoid, 17– 19 × 12–13 mm, obtuse, crustaceous, fuliginous, smooth, inserted on 3–5 × 2–4.5 mm cylindrical knobs.

Etymology: — Kairoa cromeana is named after ornithologist/ecologist Francis H.J. Crome, the principal planner and team leader of recent expeditions into PNG's southern ranges.

Field characters: —Understory shrubs, 2–4 m tall, often pole-stemmed; branchlets slightly compressed at the top, smooth, green, not ant-inhabited; leaves distichous, blades papyraceous or firm, dry-textured, shining, adaxially very dark green, abaxially yellow-green; flowers (both sexes) turbinate, obtuse, green turning dull orange-yellow at anthesis; fruiting monocarps purple-black when ripe.

Distribution: —Known only from the type locality in southeast Morobe ( Fig. 4 ).

Habitat and ecology: —Depauperate forest on ultrabasics, from sealevel to at least 50 m elevation. Locally common in open understories.

Phenology: —Flowering and fruiting in September.

Additional specimens examined (paratypes): — PAPUA NEW GUINEA. Morobe Province: Nasau Bay , natural-growth forest on ultrabasics, 7°18'S, 147°08.3'E, sealevel, 22 September 2007, Takeuchi, Ama & Siga 21771 ( A!, LAE!, M!, and 5 undistributed duplicates!); 23 September 2007, Takeuchi, Ama & Siga 21778 ( A!, LAE!, M!, and 5 undistributed duplicates!); Takeuchi, Ama & Siga 21780 ( A!, LAE!, M!) .

Kairoa cromeana is always glabrous on vegetative parts, a feature allowing for quick and convenient separation from congeners. As an alternative means of identification, an updated version of the existing key (in Renner & Takeuchi 2009: 73) is presented below:

1a. Dioecious shrubs; vegetative parts conspicuously hirsute; laminae chartaceous; stamens ca. 25, dispersed over all interior surfaces of the receptacle ............................................................................................................ Kairoa villosa

1b. Monoecious shrubs; vegetative parts glabrous, woolly, or subappressedly-hairy (but not patently hirsute); laminae thick, coriaceous or firm; stamens 2–6 or>100, inserted on the receptacle floor ........................................................ 2

2a. Leaf venation deeply impressed on upper side; pistillate flowers solitary, subsessile or at most to 2 mm pedicellate, primary bracts foliaceous, to 29 × 6 mm; staminate flowers subsessile, stamens 2 or 4 ................. Kairoa endressiana

2b. Leaf venation raised (or only slightly impressed on upper side); pistillate flowers fascicled or racemose-subpaniculate, ca. 5–10 mm pedicellate at anthesis, primary bracts minute, ca. 1 mm long; staminate flowers at least 4 mm pedicellate, stamens either 6 or>100............................................................................................................................ 3

3a. Hairs persisting on at least some parts; pistillate flowers fascicled; staminate flowers 15–20 mm pedicellate, stamens>100. ..................................................................................................................................................... Kairoa suberosa

3b. All parts glabrous or glabrescent; pistillate flowers racemose or subpaniculate; staminate flowers 4.5–8 mm pedicellate, stamens 6. .................................................................................................................................... Kairoa cromeana

Despite its gross resemblance to Kibara Endlicher (1837: 314) , the new species conforms to the recently defined generic profile for Kairoa Philipson (1980: 368 ; see Renner & Takeuchi 2009). The presence of erect anthers (longer than broad) and their vertical dehiscence is diagnostically supportive of the given assignment. Molecular sequencing on silica-dried leaf samples shows Kairoa cromeana is firmly nested in the Kairoa clade (S. Renner pers. comm., and S. Renner unpublished data).

Although the conspectus for Kairoa has expanded from one species (in Philipson 1980) to four species, the genus may be even larger than presently supposed. Judging from descriptions in Philipson (1985, 1986) several species of Kibara appear to fit the current interpretation of Kairoa . However it is impossible to be sure—current phylogenies (e.g., Renner 1998) have limited within-clade sampling intensities and at least two monimiaceous genera from Papuasia cannot be evaluated because of possible extinction(s). There remains considerable uncertainty about the generic assignments of unsequenced taxa. Morphological characters by themselves have proven unreliable as a basis for generic circumscription ( Renner & Takeuchi 2009).

Future progress in our understanding of the Mollinedioideae is dependent on application of molecular techniques to a much wider sampling base than is presently available. The desired actions are unfortunately complicated by the range-restricted distributions of many taxa (34 of the 76 monimiaceous species in New Guinea are known only from the type or from one province; Philipson 1986). Kibara , for example, is almost never found with more than two species growing together (pers. obs.).

The need for obtaining flowers of both sexes is acutely problematic for field investigators, since in addition to unpredictable phenologies, the duration of anthesis is very narrow (pers. obs.). Research itineraries must be geographically and temporally varied in order to establish an adequate foundation for taxonomic revision. Any monographic study underpinned by new collections will be thus logistically difficult and costly. Physical security issues are also constraining. At least seven species of Monimiaceae are found only in the PNG Central Highlands, an area currently associated with social disorder, crime, and excessive compensation demands.

Figures

FIGURE 1. Kairoa cromeana. Aspect, 4 m shrub at Nasau Bay, Morobe Province (from Takeuchi, Ama & Siga 21778).

FIGURE 2. Kairoa cromeana. Inflorescence comprised of flowers from both sexes. A, pistillate flowers immediately prior to receptacle abscission (abscission lines clearly visible); B, staminate flowers, smaller and inserted below the pistillate flowers in a mixed inflorescence; C, pistillate flowers with abscissed receptacle. A–B from Takeuchi, Ama & Siga 21780; C from Takeuchi, Ama & Siga 21772.

FIGURE 3. Kairoa cromeana. A, fruiting receptacle with ripening monocarps; B, branchlet with immature inflorescence at the top and anthetic inflorescence at the node below. A–B from Takeuchi, Ama & Siga 21772.

FIGURE 4. Island of New Guinea. Collection localities. A, Nasau Bay, type locality for Kairoa cromeana; B, Waskuk; C, Kamiali Wildlife Management Area (including Blue Mt.); D, Foja Mts.