Calyptochloa gracillima subsp. ipsviciensis

Calyptochloa gracillima subsp. ipsviciensis E.J.Thomps. & B.K.Simon, Austrobaileya 8 (4): xx (2012)

subspecies nova similar to C. gracillima C.E.Hubb. subsp. gracillima differing by the axillary spikelets mostly shorter (3.5–4.2 mm versus 4–5.5 mm) and narrower (0.8–0.9 mm versus 1–1.1 mm); longer anthers (0.4–0.7 versus 0.3–0.4); and by the terminal spikelets with an acute apex of upper glume (versus obtuse to truncate), and longer lower glumes when present (0.8–1.8 mm versus <0.2 mm). Typus: Queensland, Moreton District: Council reserve, cnr Reservoir Lane and Kholo Road, Ipswich, 4 April 2012, E.J.Thompson MOR711 (holo: BRI; iso: CANB, K, L, MO, NSW, SI, US).

Decumbent stoloniferous perennial. Ascending branches to 40 cm tall, copiously branched with 10–30 nodes. Stolons to c. 3 m long. Mid-culm leaf blades 20–36 mm long, 2.5–5 mm wide; adaxial surface with sparse hairs 0.5–2 mm long; abaxial surface with moderately dense simple hairs 0.5–1 mm long. Mature fertile leaf sheaths 10–15 mm long, 21.2–2.5 mm wide near base with wall 0.3–0.4 mm thick. Sterile leaf sheaths with tuberclebased bristles 0.3–0.7 mm long and simple hairs 1.5–3 mm long. Terminal inflorescences on axes 1.5–3 cm long, 5–8-flowered, spikelets 3–4.6 mm long (without awn), 1–1.6 mm wide; lateral pedicels 1–1.6 mm long, apical pedicel 2.5–4 mm long. Lower glume lanceolate, 0.7–1.8 mm long. Upper glume 2.3–4.6 mm long; apex acute. Lower lemma 2.3–4.6 mm long. Upper floret lemma 2.2–3.2 mm long, awn 0.5–2.4 mm long; lodicules 0.2 2mm long; palea 2–2.7 mm long, apex acute. Anther, 1.5–2 mm long. Caryopsis not seen. Axillary inflorescences usually present at 4 (3–5) internodes. Spikelets 3.5–4.2 mm long (without awn), 0.8–1 mm wide. Upper glume 0.7–3.5 mm long. Lower lemma 3.5–4.2 mm long. Upper lemma body 3–4.2 mm long, awn 0.5–2.5 mm long; palea 2.7–3.5 mm long. Anthers 0.4–0.5 mm long. Caryopsis 2.3–3.7 mm long, 0.5–0.8 mm wide.

Distribution and habitat: Calyptochloa gracillima subsp. ipsviciensis is endemic to southeast Queensland in the vicinity of Ipswich where it is known from a few small areas. It is an uncommon to dominant species in woodlands dominated by Eucalyptus spp. including E. crebra F.Muell.and E. moluccana Roxb. and/or Corymbia citriodora subsp. variegata (F.Muell.)
A.R.Bean & M.W.McDonald on loam to clay loam duplex soils derived from shale on gently undulating to hilly terrain. REs represented include 12.9–10.2, 12.9–10.3 and 12.9–10.19.
Associated ground layer species include Aristida caput-medusae Domin, Cleistochloa subjuncea C.E.Hubb. and Themeda triandra Forssk. The habitat is typically moderately shaded.

Phenology: Calyptochloa gracillima subsp. ipsviciensis flowers from December to March during the wet season. The cleistogamous spikelets are produced over a broader seasonal
period. Notes: Until 2011 there were no specimen records of Calyptochloa gracillima at BRI from the Moreton Pastoral District near Ipswich. These new records represent a disjunction of over 200 km from the previous known southern limit of the species.

Calyptochloa gracillima subsp. ipsviciensis is similar to C. gracillima subsp. gracillima in growth habit but on average it is taller, the mats cover a greater area and the leaves are more yellowish green. C. gracillima subsp. ipsviciensis also differs by the mostly thinner walled fertile leaf sheaths, and often the proportionally shorter fertile leaf sheath in relation to the internode length. Generally the fertile leaf sheaths cover about half the length of the culm internodes whereas for C. gracillima subsp. gracillima the leaf sheath usually covers most of the length of the culm internode. Only spikelets towards the apex of racemes of terminal inflorescences have a lower glume present, but it is often absent.

The distribution of this subspecies overlaps with Ottochloa gracillima C.E.Hubb. and Entolasia marginata (R.Br.) Hughes, both of which it could easily be confused with in the field in terms of growth habit and leaf colour and size although to date these species have not been seen growing with C. gracillima. Ottochloa gracillima and Entolasia marginata are distinguishable in the field by the branched inflorescences, the smaller glabrous spikelets and the abaxial leaf surface which is glabrous to sparsely hairy.

Etymology: The subspecies epithet is derived in reference to the name of the nearby city of Ipswich where it has been found.

Conservation status: Calyptochloa gracillima subsp. ispviciensis is only known from a few locations near the urban centre of Ipswich, two of which are Ipswich City Council reserves. At two locations only one or two plants or mats have been observed. The very restricted range and the few small populations suggest this subspecies should be considered Critically Endangered (criterion B1a,b [IUCN 2001]). Current threats include invasion from weeds such as Megathyrsus maxima var. pubiglumis (K.Schum.) B.K.Simon & S.W.L.Jacobs and Lantana montevidensis (Spreng.) Briq., inappropriate burning regimes, urbanisation and road construction.

Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith