Ptisana soluta (Compton) Murdock & Perrie, 2023

Shepherd, Lara D., Murdock, Andrew G., Amice, Rémy & Perrie, Leon R., 2023, A synopsis of Ptisana Murdock ferns (Marattiaceae) in New Caledonia based on sequence data and morphology with the recognition of a new vulnerable species, P. soluta (Compton) Murdock & Perrie, comb. nov., stat. nov., Adansonia (3) 45 (3), pp. 41-59 : 53-59

Ptisana soluta (Compton) Murdock & Perrie , comb. nov., stat. nov.

( Figs 3 ; 5 )

Ptisana soluta (Compton) Murdock & Perrie comb. nov., stat. nov. differs from Ptisana attenuata (Labill.) Murdock in bearing leaves with smooth, mottled green-brown stipes, and laminae that are 3-pinnate proximally, 2-pinnate distally, and differs from Ptisana salicina (Sm.) Murdock in bearing synangia that are removed from the margin, and laminar division as previously described.

Marattia smithii Mett. ex Kuhn forma soluta Compton , Journal of the Linnean Society, Botany 45: 456 ( Compton 1922).

— Type: New Caledonia. Ignambi, 1500 ft., 4.VIII.1914, Compton 1674 (holo-, BM [ BM000787128 ]!).

ETYMOLOGY. — Compton (1922) originally described this species as Marattia smithii Kuhn forma soluta Compton and noted the lamina character that distinguishes this taxon. The Latin “ soluta ” means “separate from adjacent parts, breaking up”, presumably in reference to its transition between 2- and 3-pinnate states.

HABITAT AND DISTRIBUTION. — Based on available collections, Ptisana soluta comb. nov., stat. nov. is endemic to New Caledonia, where it is widespread but uncommon on Grande Terre. It is known from Mt. Ignambi and Mt. Panié in the northeast, near Canala in the central-east, and near Nouméa in the southwest ( Fig. 4 ). One collection from Sommet Arago (Compton 1442, BM) may be this species, but was described as being from a population of 2-pinnate plants; this requires further investigation. Several collections note a (rain-) forest and/or mountain habitat, with recorded elevations ranging from 200 m to 800 m. Based on Fig. 4 , it seems to be on non-ultramafic substrates, although it may come at least close to ultramafics on Koghis. At Koghis, P. soluta comb. nov., stat. nov. grows intermixed with P. attenuata and Angiopteris evecta . Additional study of the ecological range of P. soluta comb. nov., stat. nov., and how it may differ from P. attenuata , is needed.

CONSERVATION ASSESSMENT. — We suggest that Ptisana soluta comb. nov., stat. nov. be ranked as Vulnerable (VU B1ab(i,i i,iii,iv,v)+2ab(i,ii,iii,iv,v), IUCN 2012), with this provisional until verified by the New Caledonia Plants Red List Authority. The estimates of 60 km 2 for area of occupancy and 4236 km 2 for extent of occurrence are well under the thresholds for criterion B of the Vulnerable category. The subcriteria 1b and 2b are met because of ongoing, substantive predation by rusa deer and feral pigs, as is the case with P. attenuata ( Endemia Red List Authority 2022) . The subcriteria 1a and 2a both invoke “no more than 10 locations”. The exact number of locations is unclear, particularly with the imprecision of earlier collections, but given the mobility of the deer and pig threats, known locations could be defined as: 1-2 in the southwest, one in the central-east, and 2-4 in the northeast (see Fig. 4 ). Ptisana soluta comb. nov., stat. nov. is unprotected by legislation, but occurs within reserves at Thy Valley and Mt. Panié. The priority for its management should be searching for new sites and surveying known localities, particularly the accessible Koghis and also Ignambi, where Compton (1922) said this form was “abundant”.

DESCRIPTION

Fronds 3-pinnate proximally, transitioning to 2-pinnate distally, at least 4 m long, bearing 4-6 pairs of opposite pinnae on mature fronds, the terminal pair forking at the frond apex. Stipe circular in cross-section, smooth, mottled green-dark brown, subtended by paired stipules, round, shallowly divided to nearly entire with ragged margins. Swollen pulvini present at the base of all segments, green, smooth. Ultimate segments 35-104 mm long × 6.5-19.1 mm wide on 3-pinnate portions, 163-295 mm long × 13.7-35.6 mm wide on 2-pinnate portions, oblong with acuminate apices. Laminae dark green above, lighter below, herbaceous-coriaceous, with occasional ciliate scales abaxially along veins and midribs. Veins free, c. 2 mm apart, occasionally dividing once. Leaf margin sub-entire-minutely serrate, more clearly serrate near apex. Synangia green when immature, tan-brown after opening, one per vein, submarginal, set back from leaf margin by 1-3 mm, 2-3.5 mm long × c. 1 mm wide, longer and with more locules on larger segments, receptacles bearing short, branched, uniseriate hairs.

Ptisana soluta comb. nov., stat. nov.

Balansa 1559, Canala, 20.XI.1869, P[P00522621, P00522622, P00522623, P00522624, P00522625, P00522626]; Braithwaite 559, no locality or date, NOU[ NOU056668 , NOU056674 , NOU056675 ]; Buchholz 1230, Thy River, 20.X.1947, P[P00518375], UC [799340]; Compton 1674, Ignambi, 1914, BM[ BM000787128 ] [holotype of Marattia smithii f. soluta ]; Foster 156, Ignambi, 12.VI.1956, UC [ UC1053924 ]; Franc 1911 [sic] (Rosenstock 122), no locality or date, P[P01365760]; Franc 2376, Monts Koghis, 6.X.1929, P[P00522537]; Franc 2377, Monts Koghi , 6.X.1929, P[P00518354]; Franc 749, Mts Koghis , IV.1912, P[P01365700, P01365758, P01365759]; Franc 749, Monts Koghis , 25.VII.1912, P[P00522537, P0522637, P01365699]; Franc 749, no locality or date, UC [ UC392870 ]; Franc s.n., Mont Koghi, IV.1911, P[P00522539, P00522540, P0522541, P0522542]; MacKee 4795, Mt Ignambi, 12.VI.1956, P[P00522796]; no collector, locality, or date, P[P00522786]; Pancher s.n., Montrouzier , 1855, P[P00518388]; Perrie et al. 8330, Koghis, 20.X.2019, WELT [ P030314 ], NOU[ NOU090683 , NOU106931 ]; Pinard s. n., Nord , 1856, P[P00522776]; Schmid 17, Koghis, 14.I.1965, NOU[ NOU056662 ]; van derWerff & McPherson 15907, Mt. Panié , 23.X.1999, NOU[ NOU056685 ], UC [ UC1740300 ]; Vieillard 1681, Balade, no date, P[P0522758, P00522759, P01365709]; Vieillard 1681, Pouébo, no date, BM[ BM000785905 ].

Possible P. soluta comb. nov., stat. nov. (not mapped) Balansa 1560, Canala, 20.XI.1869, P[P00522544, P00522545]; Balansa 801, Mont Mi, 16.III.1869, P[P00522546, P00522547]; Compton 1442, Mont Arago, 14.VII.1914, BM[BM000785888]; MacGillivray 29, no locality, VI.1858, P[P01646578]; MacGillivray 729, no locality, VIII.1858, P[P00522642, P00522797], BM[BM000785896]; Pancher 1680, no locality or date, P[P00522781]; Pancher s.n. no locality, 1870, P[P00522534, P00522536]; Pancher s.n., no locality or date, P[P00522459, P00522780, P00522782, P00522783]; Suprin 1481, Thy, 20.XI.1981, P[P01365254].

Figures

FIG. 3. — Ptisana soluta (Compton) Murdock & Perrie, comb. nov., stat. nov., field photos: A, frond with lamina 3-pinnate proximally and 2-pinnate distally. The frond at top-right is P. attenuata (Labill.) Murdock; B, stipes are greenish-brown at a distance; C, abaxial surface of costae and fertile lamina, showing transition from 3-pinnate to 2-pinnate; D, stipe greenish-brown and smooth; E, stipules around stipe bases. Photos: A-D, Leon Perrie from near Nouméa; E, Rémy Amice, from near Nouméa.

FIG. 5. — The holotype of Ptisana soluta (Compton) Murdock & Perrie, comb. nov., stat. nov. (Compton 1674, Ignambi, 1914, BM[BM000787128]) showing how the lamina transitions from 3-pinnate proximally to 2-pinnate distally. CC BY The Trustees of the Natural History Museum, London.

FIG. 4. — Distribution map for the New Caledonian endemic species of Ptisana attenuata (Labill.) Murdock (), P. rolandi-principis (Rosenst.) Christenh. (Δ), and P. soluta (Compton) Murdock & Perrie,comb.nov., stat.nov. (, with unvouchered field observations indicated by a broken outline).Shaded areas are ultramafic substrates. The collecting sites of the sequenced P. attenuata samples are indicated.