Champia farlowii M. K. Griffith, C. W. Schneider et C. E. Lane 2017, sp. nov.

Figures 3–10

Plants reddish-brown to pink and greenish-red, erect to 5–8 cm tall, upright axes arising from small discoidal holdfasts; axial segments terete, barrel-shaped and constricted at septal regions, 1.0–1.5 diameters long in mature portions decreasing in length and width distally; branching mostly at septa, occasionally from internodal regions (Fig. 7), mostly alternate but often opposite or irregular, frequently with multiple branches arising from the same node; main axes 1–2 mm in diameter, occasionally anastomosing with other branches; in surface view, septal cells in a single layer (Fig. 5), angular and isodiametric, 36–95 μm long and 38–65 μm in diameter; cortex a single layer with two different cell sizes, larger cells irregularly polygonal to ovoid, 31–84 (–115) μm long and 20–42 μm in diameter, darkly staining smaller cells, subspherical to spherical, 10–22 (–27) μm in diameter, interspersed among them (Fig. 6); thin longitudinal filaments 4–12 μm in diameter arising from where the septum join the cortical layer, running down the inner surface of the cortex surrounding the central mucilage-filled cavity of each segment, producing gland cells on the cavity side of the filaments, 5–6 μm in diameter; hair cells observed in some specimens originating from the small outer cortical cells; tetrahedral sporangia spherical 52–80 μm in diameter, scattered in the cortex (Fig. 8), developing in mature segments several segments from the branch apices, abundant and obvious to the naked eye; mature cystocarps 500–845 μm in diameter and 650–910 μm tall, broadly ovoid to spherical and ostiolate at maturity, produced singly or in groups of 2–5 per node (Fig. 9), tela arachnoidea present between the carposporophyte and pericarp wall (Fig. 10); carpospores obpyriform, 23–40 μm in diameter and 57–75 μm long; spermatangia unknown.

Holotype ( designated here): Northwestern Atlantic Ocean, United States, Rhode Island, Charleston, Quonochontaug Central Beach, 41˚20’12.8” N, 71˚42’06.8” W, shallow subtidal and drift, ⊕, 21 July 2015, C. W. Schneider (CWS) 15-27-2 [EC059, deposited in MICH] (Fig. 4); Isotype, ⊕, [EC060, Herb. CWS].

Selected collections (genetic collections listed in Table 1): UNITED STATES. Massachusetts: Little Harbor, Woods Hole, July 1893, W. A. Setchell, P. B.- A. no. 290 (Collins et al. 1897, as C. parvula); Edgartown, August 1897, M. W. Jernegan, P. B.- A. no. 592 (Collins et al. 1899, as C. parvula) (Fig. 3); Nantucket Is., Siasconset Beach, 41˚15’40.5” N, 69˚57’43.6” W, 6 October 2007, CWS 07-4 - 13; Cuttyhunk Is., Church’s Beach, 41˚25’33.42” N, 70˚55’54.60” W, 18 September 2009, W. M. Brown / CWS 09-52- 1. Rhode Island: Charleston, Quonochontaug Central Beach, loc. cit., 21 August 1994, CWS 94-3 - 5; Newport, Brenton Point State Park, 41˚27’06.43” N, 71˚21’25.66” W, 27 June 1999, CWS 99-5 - 4; Watch Hill, Napatree Point, 41˚18.3’ N, 71˚53.0’ W, 3 August 2000, V. S. Schneider / CWS 00-6-8; Charlestown, Quonochontaug Central Beach, loc. cit., 3 August 2010, CWS 10-4 - 2. Connecticut: Bridgeport, Bridgeport Harbor, 2 September 1891, I. Holden; Waterford, Pleasure Beach outcropping, 41˚18’28.67” N, 72˚08’54.14” W, 31 July 1975, CWS 1029; Waterford, Fox I. South, 41˚18’28.67” N, 72˚08’54.14” W, 12 October 1976, CWS 1318; Waterford, Pleasure Beach, loc. cit., 28 October 1984, CWS 3022; Groton, Bluff Point, 41˚18’54.6” N, 72˚02’11.9” W, 24 August 2009, CWS 09-40 - 1; Stonington, Barn Is. boat launch, 41˚20’13.9” N, 71˚52’32.0” W, 24 August 2009, CWS 09-41 - 2. New York: Montauk, Long Island Sound, 41˚02’33.84” N, 71˚58’36.60” W, 11 October 2009, A. K. Kivela / CWS 09-54- 5 [all Herb. CWS!].

Geographic Distribution: Presently known from genetic isolates and collections in southern New England, south of Cape Cod, and Long Island, NY, but also growing in warm bays of Massachusetts to the north of the Cape.

Etymology: The epithet “ farlowii ’ honors William Gilson Farlow (1844-1939), noted Harvard phycologist of the 19 th century, who extensively surveyed the macroalgal flora of New England, and was the first to illustrate Champia from New England (Farlow 1881, pl. XV).