Tuesday, October 9, 2018

[Botany • 2018] Phlegmariurus vanuatuensis (Huperzioideae, Lycopodiaceae) • A New Species from Vanuatu, Re-circumscription of P. nummulariifolius and New Combinations in Phlegmariurus

(D, E, F) Phlegmariurus vanuatuensis A.R.Field
(C) Phlegmariurus nummulariifolius (Blume) Ching
 in Field, 2018

Phlegmariurus vanuatuensis A.R.Field is described as a new species for plants endemic to the islands of Vanuatu that were previously identified with P. nummulariifolius (Blume) Ching. The Vanuatuan species differs from the widespread Asian-Oceanian species in several characteristics, most notably its acutely divergent leaf arrangement and thicker less branched fertile spikes. Phlegmariurus nummulariifolius is here re-circumscribed as plants occurring in Asia and into Oceania as far east as the Solomon Islands, being replaced eastwards by P. vanuatuensis. In addition, new nomenclatural combinations are made for Phlegmariurus australis, a species from Polynesia and for Phlegmariurus copelandianus, a species from Malesia.

Keywords: Phlegmariurus, Lycopodiaceae, Vanuatu, Oceania

Figure 1. Phlegmariurus vanuatuensis  ARF1140: A habit, leaf arrangement and fertile spikes B close up of sterile leaf arrangement showing subopposite decussate leaf arrangement and ovate-oval leaves C close up of fertile spike showing scale like sporophylls and a sporangium.
Scale bar: 10 cm (A); 1 cm (B, C). Illustration by A.R.Field. 

Figure 2. Phlegmariurus nummulariifolius ARF0002: A basal region of shoot showing branching pattern and leaf arrangement B medial region of shoot showing adpressed leaf arrangement in facial and lateral view C distal region of shoot showing abrupt transition to sporophylls and filiform fertile spikes.

Phlegmariurus vanuatuensis ARF1140
D basal region of shoot showing branching pattern and leaf arrangement E medial region of shoot showing divergent leaf arrangement in facial and lateral view F distal region of shoot showing gradual transition to sporophylls and funiform-filiform fertile spikes. 

Photos by A.R.Field

Phlegmariurus vanuatuensis A.R.Field, sp. nov.

Diagnosis: Phlegmariurus vanuatuensis is similar to Phlegmariurus nummulariifolius but differs in having acutely spreading non-flattened sterile leaves (compared with adpressed and imbricate leaves flattened in on plane in P. nummulariifolius), thicker pale green-brown stem bases 3.5–5.5 mm diameter in P. vanuatuensis (compared to thinner dark black-brown stem bases 1.5–3.5 mm diameter in P. nummulariifolius) and a gradual transition to thicker less ramified fertile spikes 2–5.5 mm diameter in P. vanuatuensis (compared to an abrupt transition to slender ramified fertile spikes 1–2.5 mm in P. nummulariifolius).

Distribution, habitat and ecology: Endemic to Vanuatu where it occurs as an uncommon epiphyte on the bark of tree trunks and branches in the canopy to subcanopy of mature trees in lowland to montane primary tropical rainforest.

Etymology: Named for the origin of this species in Vanuatu. Vanuatu is a composition of the Austronesian words ‘Vanua’ meaning home or land and ‘Tu’ meaning stand.

 Ashley Raymond Field. 2018. Phlegmariurus vanuatuensis (Huperzioideae, Lycopodiaceae) A New Species from Vanuatu, Re-circumscription of P. nummulariifolius and New Combinations in PhlegmariurusPhytoKeys. 109: 53-66. DOI: 10.3897/phytokeys.109.29359

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