Dichanthelium androsense LeBlond & Sorrie, 2024

Dichanthelium androsense LeBlond & Sorrie , sp. nov. ( Fig. 20 View FIG ).

TYPE: THE BAHAMAS: North Andros District: wet Pineland off NE side of a connector road heading NW towards Main Lumber Road from Queen’s Highway at a point 8.7 mi S of the North Andros airport,lat.24.9353, long.–78.0409; 6 May 1993, LeBlond 3266, Sorrie, & Weakley (HOLOTYPE: NCU), Sorrie 7220, LeBlond, & Weakley (ISOTYPE: US) .

Diagnosis.— Dichanthelium androsense superficially resembles D. acuminatum var. acuminatum with its small spikelets, ciliate blades and overall pubescence, but differs from it and all other known Dichanthelium taxa by a combination of its short, bushy ligule and the absence of a pseudoligule; glabrous to glabrate spikelets; shiny and often glandular to stipitate-glandular glumes and lower lemma; and sheath papillae that are distinctly red-orange and swollen in situ (this character lost in drying).

Description.— 1–several culms together, cespitose, nonrhizomatous. Culms to 40 cm, slender, 0.4–1.1 mm in diameter at lowest elongate internode; internodes moderately pilose or papillose-pilose with hairs 0.5–2 mm long; nodes, especially lower, bearded with retrorse hairs (hairs of the nodes and internodes often lost as specimens age). Rosette leaves 1.5–3 cm long × 3-5 mm wide, moderately-densely pubescent abaxially, sparsely pubescent adaxially, margins ciliate. Culm leaf sheaths half or less as long as internodes, moderately pilose to papillose-pilose with variably spreading hairs (0.5–) 1–2 mm long ( in situ , sheath papillae are distinctively red-orange and swollen, but this character is lost in drying). Ligule cilia bushy, 0.5–0.8(–1.3) mm long, membranous portion minute or absent, without a distinct pseudoligule. Blades 2–5.5 cm long × 2-5 mm wide, usually ciliate distally as well as proximally, moderately to sparsely pilose adaxially with appressed hairs, moderately densely papillose-pilose abaxially with non-appressed hairs. Vernal panicles ± 3 cm long × 1.5 cm wide (few seen, these senescent), rachis sparsely pilose with spreading hairs to 0.3 mm long; rachis, branches, and pedicels minutely scabrous. Spikelets elliptical, obtuse, (1.4–)1.5–1.6(–1.7) mm long, the glumes and lower lemmas shiny, sometimes glandular to stipitate-glandular, glabrous to sparsely puberulent; lower glumes 0.5–0.6(–0.7) mm long, obtuse to broadly acute; upper glumes and lower lemmas equaling upper lemmas. Autumnal sheaths and blade abaxial surfaces densely (-sparsely) pubescent with spreading hairs 0.2–0.5 mm long; autumnal panicle indumentum similar to vernal. None of the vegetative features can be described as velvety-pilose.

Etymology.— The taxon was determined to be distinct by examining plants collected on North Andros Island in The Bahamas, and only known from that island as of this accounting.

Additional collections (paratypes). THE BAHAMAS. North Andros District: wet Pineland off west side of Main Lumber Road N of junction with SE-NW connector road from Queen’s Highway , 15 Mar 1992, LeBlond 2666 & Sorrie ( FTG); same location, 4 May 1993, LeBlond 3250, Sorrie, & Weakley ( MO); N side of Cross Creek and W side of Main Lumber Road 2.4 mi N of junction with SE-NW connector road from Queen’s Highway, 4 May 1993, Sorrie 7202, LeBlond, & Weakley ( FLAS); marsh/pineland ecotone near wellfield SW of Nichols Town , off road to Red Bays , 7 May 1993, LeBlond 3272, Sorrie, & Weakley ( FSU) .

Distribution and ecology.— Currently, Dichanthelium androsense is only known from North Andros Island. The island’s climate is maritime subtropical, with tropical summers and warm temperate winters ( Sealey 1994). The geological substrate is oolitic and bioclastic limestone ( Frazer & Eshbaugh 1996). Plants were primarily found beneath an open canopy of Pinus caribaea Morelet var. bahamensis (Griseb.) Barrett & Golfari. The primary habitat is the Pineland wet variant of Correll (1979) and Nickrent et al. (1988). This habitat is ecotonal in character between the denser and more inland canopies of the Pineland dry variant and the terrestrial reaches of the Saltwater Marsh community ( Nickrent et al. 1988) (also known as swash), which become brackish to fresh inland.

The Pineland wet variant community is characterized by having water within a few inches of the surface, with an open canopy of Pinus caribaea var. bahamensis . According to Correll (1979) and Nickrent et al. (1988), woody plants include Metopium toxiferum ( L.) Krug & Urban, Byrsonima lucida (Mill) DC. , Exostema caribaeum (Jacq.) Roem. &Schult. , Coccoloba spp. , Guapira discolor (Spreng.) Little , Pithecellobium guadalupense Chapm. , Corchorus hirsutus L., Bourreria ovata Miers , and Lantana involucrata L. Vines include Smilax laurifolia L., Ipomoea microdactyla Griseb. , Rhabdadenia biflora (Jacq.) Muell. , and Centrosema virginiana ( L.) Benth. Herbs include Rajania hastata L., Rhynchospora colorata ( L.) H. Pfeiff., Chloris petraea Sw. , and Andropogon spp. Structurally and compositionally, this habitat is clearly a “tropical relative” of Wet Pine Savanna habitats found in the southeastern United States.

Plant associates at the Pineland wet variant sites of Dichanthelium androsense include Pinus caribaea var. bahamensis , Metopium toxiferum , Thrinax morrisii H. Wendl. , Cordia bahamensis Urban , Stigmaphyllon sagraeanum Juss. , Ernodea littoralis Sw. , Rhynchospora colorata, Tetrazygia bicolor (Mill.) Cogn. var. bicolor , Linum bahamensis Northrop var. corallicola (Small) Rogers , Waltheria bahamensis Britton , Psidium longipes (Berg) McVaugh , Anemia adiantifolia ( L.)Sw., Schizachyrium gracile (Spreng.) Nash , Smilax havanensis Jacq. , Andropogon virginicus L.(s.l.), Jacquemontia verticillata ( L.) Urban, Aletris bracteata Northrop , Setaria chapmanii (Vasey) Pilg. , Zamia pumila L., and Dichanthelium caerulescens . Habitat at the site located off the road to Red Bays is ecotonal between the Pineland wet variant community and the Tussock Marsh community described by Sorrie & LeBlond (1997).

Discussion.— The small spikelets, ciliate blades, and overall pubescence suggest a relationship with Dichanthelium acuminatum (Swartz) Gould & C.A. Clark in sect. Lanuginosa , but the Andros plants differ by lacking a pseudo-ligule behind the short ligule and by the absence of velvety pubescence. They also differ by characters of the spikelet and leaf sheaths. Both glumes and the lower lemma are shiny and often glandular to stipitate-glandular, and glabrous to sometimes sparsely pubescent. In situ , sheath papillae are distinctly red-orange and swollen, but this character is lost in drying. Plants were primarily found beneath an open canopy of Pinus caribaea Morelet var. bahamensis (Griseb.) Barrett et Golfari. Four additional species of Dichanthelium are known from the Bahamas: D caerulescens (Hackel ex Hitchc.) Correll , D. commutatum (Schult.) Gould , D. dichotomum ( L.) Gould var. nitidum (Lamarck) LeBlond , and D. neuranthum (Griseb.) LeBlond. All but D. commutatum are known from North Andros Island ( Correll & Correll 1982; Sorrie &LeBlond 1997). Dichanthelium caerulescens has been found in the same habitat as D. androsense .