Pytinicarpa comptonii Gâteblé, Lannuzel & M.Pignal, 2022

Lannuzel, Guillaume, Pignal, Marc & Gâteblé, Gildas, 2022, Pytinicarpa (Asteraceae, Astereae) in New Caledonia, Phytotaxa 574 (2), pp. 121-136 : 123-126

Pytinicarpa comptonii Gâteblé, Lannuzel & M.Pignal , nom. nov. ( Figs. 1 , 2 , 3 ).

Lagenophora neocaledonica S. Moore (1921: 345) .

Type :— NEW CALEDONIA. North Prov., Taom, 2500 feet [762 m], 2 December 1914, R. H. Compton 2305 (Lectotype: BM barcode BM 000629629image!, designated here; Fig. 1 ).

Perennial rhizomatous herbs; roots fibrous; stem usually absent or very short (leaves in basal rosette). Leaves 5–20, obovate to spatulate, 1.5–8 cm long × 0.4–1.5 cm wide (3.5–5.5× longer than wide), lamina gradually attenuated to the base, petiole-like base 0.1–3 cm long; lamina apex obtuse to acute with a terminal tooth or lobe; margins lobate or dentate, usually with 3–8 lobes or teeth per side, lobe depth varying from 0 to 3 (–5) mm; upper lamina surface greyish-green; glabrous or with scattered appressed trichomes, ca. 0.05 mm long; lower lamina surface pale green, glabrous; leaf margins ciliate with trichomes, ca. 0.3 mm; secondary veins obscure on both sides on fresh material, sometimes visible on dry material. Scapes generally 1–3 per tuft, (6–) 10–17 (–22) cm long, 1–1.4 mm diameter; bracts 2–7, 2–5 × 0.5 mm with trichomes 0.2–0.5 mm long; 15–20 trichomes (0.5 mm long) per mm ² at mid-point of scape, 40–60 appressed trichomes (0.5 mm long) per mm 2 towards apex. Capitula 4–6 mm long, 4–5.5 mm diameter; phyllaries ca. 25 in 2–3 rows, lanceolate, apex acute to rounded, glabrous or with trichomes ca. 0.3 mm occasionally along mid-rib on outer surface, with fringed margins in distal half, outer phyllaries 2–2.9 × 1 mm, inner phyllaries 2.7–3.7 × 1–3 mm. Receptacle conical at anthesis, 2–3 mm diameter and 1–2 mm high. Ray florets female, 11–20 in 1 row; tube 0.9–1.1 mm long, ca. 0.3 mm wide, glabrous, greenish; ligules 3.1–6.3 × 1.2–2.4 mm, with longitudinal veins obscure, glabrous, white or very occasionally pink, apex obtuse, retuse or bidentate; style branches ca. 1 mm long; ovary 1.6–2.2 × 0.5–0.6 mm. Disc florets male, 25–50, tubular, 1.7–3.2 mm long, glabrous; corolla lobes (4–) 5, deltate, 0.4–0.6 × 0.3–0.4 mm; stamens 4–5, anthers ca. 1.2 mm long; style branches ca. 1.2 mm long; sterile ovary 0.8–1.2 mm long; corolla greenish, pappus scales absent. Cypselae oval in cross section, lacking beak, oblanceolate, 2.6–3 × 0.9–1 mm, uniformly brown at maturity; surfaces with 1–3 longitudinal ribs on each side.

Distribution and habitat:—Restricted to the massifs of Ouazangou and Taom areas from low (50 m) to high (1000 m) elevations in the northwest of Grande Terre ( Fig. 3 ). It grows in open scrubland (maquis minier) on ultramafic substrates, on serpentines and even serpentinic alluvium at the base of the massifs and on peridotitic derived soil at higher elevations.

Phenology:—Herbarium specimens indicate flowering from February to May, July and September through to November. The species might therefore be able to flower all year round.

Etymology:—The proposed new name is to acknowledge the extensive collections made by Robert Harold Compton (1886–1979) in New Caledonia during the years 1914–1915.

Conservation status:— Pytinicarpa comptonii is limited to the two nearby ultramafic massifs of Ouazangou and Taom, usually united as the Ouazangou–Taom massif. The threats to this species are different between populations present at the base or at the top of the mountains. The low elevation maquis of Tinip is subject to anthropogenic fire threats and to civil engineering structures (mining roads, roads, housing, electrification pylons, settling ponds/ decanters...). The high-elevation maquis populations are threatened by open nickel mining activities, especially on the Ouazangou mountain ( Ititiaty et al. 2020) and, to a lesser extent, on that of Taom. The northern part of the Taom massif (Homédéboa) has been subjected to nickel mining in the past, but that activity has ceased. The species can be considered as very threatened in the Tinip, Ouazangou and Taom localities and less threatened in that of Homédéboa. With four localities, an EOO of 72 km ² and an AOO of 32 km ², the species is proposed as Endangered (EN) under criterion B,i.e. B1ab(i,ii,iii,iv,v)+2ab(i,ii,iii,iv,v), using IUCN (2019) guidelines.

Notes:—Main diagnostic characters are the rosulate habit (rarely with a developed stem underground as a plant on P03276840), spatulate lamina glabrous or with short trichomes, along with glabrous ray and disc florets. All specimens are similar in flower shape and pubescence, leaf shape and pubescence. The main difference is in the leaf size. Specimens from Tinip (low elevation) have slightly smaller leaves, which are more serrate than sinuate, similar to the specimens from Taom (1000 m), while specimens from Ouazangou (800 m) have larger lobate leaves. The cypsela shape can be variable between populations, but an X-ray analysis (data not shown) showed that it might be due to comparison between viable versus non-viable cypselae. Taken together, the glabrous ray floret and the absence of long trichomes on leaves are a clear distinction between this species and P. sarasinii and P. kaalaensis . The only other species to have glabrous ray floret tubes, P. tonitrui , differs by its long, sometimes linear leaves. In addition, the trichomes, when present, are much longer in P. tonitrui . It is also similar to the two New Caledonian Lagenophora species, regarding the leaf shape, and the venation pattern, not typical of Pytinicarpa , as defined by Nesom (1994a). The absence of glandular beak on cypsela is however a character of Pytinicarpa . In the absence of further molecular studies, we here chose to follow Nesom (1994a) and keep this species in the genus Pytinicarpa .

The combination of Moore’s epithet neocaledonica in Pytinicarpa is not possible because this would be a later homonym of Pytinicarpa neocaledonica (Guillaumin) G.L.Nesom (which is based on Brachyscome neocaledonica Guillaumin ), so we propose a replacement name for this species.

There is only one sheet of Compton 2305 in BM, and no other specimen could be found in other herbaria. There are four plants on the sheet ( Fig. 1 ). All plants are on the right side of the sheet and are separated by a handdrawn line. This suggests that other plants might have previously been on the sheet. Furthermore, there is no sign of Moore’s handwriting on this sheet and no mention of BM in the protologue. However, BM’s Asteraceae curator (Ranee Prakash), when asked about this, considered it usual practice at that time to draw a pencil line when there was more than one plant on a sheet and to keep space for eventual future plants to be mounted on the same sheet. Considering these facts, the specimen is best considered as a lectotype, rather than a holotype.

The specimen MacKee 37169 (NOU019509), held at NOU, bears an error on the wrapper. MacKee’s field notebook (held at NOU Herbarium) shows that n°37169 is a Helichrysum specimen and n°37170 a Brachyscome . Consequently, the correct collecting number is 37170 and both specimens NOU019509 and P03276836 represent the same collection.

Specimens examined:— NEW CALEDONIA. North Prov. : Taom, 12 September 2006, Barrière & Rigault 25 ( NOU014338 !) ; Tinip , en contrebas du Pic Biki, 25 February 2004, Dagostini, Rigault & Fambart-Tinel 827 ( NOU003007 !) ; Tinip , 80 m, 20°46’46.77”S, 164°27’32.35”E, 24 Apr 2017, Gâteblé 856 ( NOU105132 !) ; Tinip , 70 m, 1 October 2018, Gâteblé & Lannuzel 1064 ( NOU108019 !) ; Mont Ouazangou , proche du sommet, 850 m, 20°44’33”S, 164°29’43”E, 3 July 2018, Lannuzel & Loslier 171 ( NOU090305 !) ; Tinip (Ouaco to Gomen), 19 October 1956, MacKee 5467 ( L.1815300image!, P03292519 !) ; Mont Ouazangou , base ouest, 20 m, 11 September 1967, MacKee 17527 ( NOU054763 !) ; Taom , Mont Homédéboa, 800–900 m, 16 May 1968, MacKee 18825 ( P04427670 image†!) ; Taom , Mt. Homédéboa, 800–900 m, 16 October 1969, MacKee 20970 ( P04234037 !) ; Taom , Mt. Homédéboa, 800– 900 m, 3 November 1971, MacKee 24567 ( P04427678 image†!) ; Taom , Ouéou, 350 m, 4 July 1978, MacKee 35349 ( NOU019511 !, NSW 939387 , P03276838 !) ; Mont Taom , crête Est, 1000 m, July 1979, MacKee 37169 [37170 – see notes] ( NOU019509 !) ; Mont Taom , crête Est, 1000 m, 13 July 1979, MacKee 37170 ( P03276836 !) ; Mont Taom , contrefort NO, 900 m, 8 February 1980, MacKee 37837 ( NOU054765 !, P03276840 !) ; Plateau sommital Mont Ouazangou, 800 m, 26 March 1980, MacKee 37952 ( CANB 284963.1 , NOU019510 !, P03276834 !) ; Vers le sommet de Taom, 1000 m, 24 March 1982, Suprin 1735 ( NOU019513 !) ; Plateau du massif de Taom, vers 1000 m, 24 March 1982, Veillon 4838 ( NOU054764 !) .

Figures

FIGURE 1. Compton 2305 (BM000629629). Designated lectotype of Lagenophora neocaledonica S.Moore.

FIGURE 2. Pytinicarpa comptonii Gâteblé, Lannuzel &M.Pignal, nom. nov.A. Habit; B. Capitulum; C. Capitulum with mature cypselae; D. Disc floret; E. Ray floret; F. Cypsela. A–C, E–F from Gâteblé 1064, D from Lannuzel 171. Photos A–C from G. Gâteblé, D–F from G. Lannuzel. Scale bars: 1 mm.

FIGURE 3. Distribution of Pytinicarpa comptonii Gâteblé, Lannuzel & M.Pignal, nom nov. Inset (A) shows the Ouazangou–Taom massif. Grey shaded areas represent ultramafic outcrops.