In celebration of Dr. John J. Engel: A tribute to 40 years in bryology Botany NEW SERIES, NO. 47 Part Eight: Hornworts Chapter Twenty: Taxonomic Studies of the Australian Anthocerotophyta II: The Genus Phaeoceros D. Christine Cargill1 and Bruce A. Fuhrer2 1 Centre for Plant Biodiversity Research, Australian National Herbarium, GPO Box 1600, Canberra, ACT 2601, Australia 2 25 Sunhill Avenue, Ringwood, Victoria, Australia Accepted May 20, 2008 Published November 24, 2008 Publication 1550 Abstract Four species within the hornwort genus Phaeoceros are recognized and described for Australia: the cosmopolitan P. carolinianus (Michx.) Prosk.; two new combinations of taxa endemic to Australia—P. evanidus (Steph.) Cargill & Fuhrer comb. nov., P. inflatus (Steph.) Cargill & Fuhrer comb. nov.; and a species new to science, P. engelii Cargill & Fuhrer sp. nov. A key to all four species is also given. Introduction The hornworts have become a pivotal group in understanding the transition from nonvascular land plants to vascular land plants (Qiu et al. 2006). A seemingly homogeneous group, recent molecular and ultrastructural studies have revealed a surprisingly diverse group of plants. Traditional relationships have been discarded, such as that between Anthoceros L. emend. Prosk. and Phaeoceros Prosk., others have been confirmed, such as between Megaceros Campb. and Dendroceros Nees., and new and novel ones have been revealed, such as the position of the unique FIELDIANA: BOTANY, N.S., NO. 47, NOVEMBER 24, 2008, PP. 239–253 239 Leiosporoceros Hässel (Duff et al., 2004, 2007; Cargill et al., 2005). These studies have concentrated on relationships at the level of genera and higher yet species boundaries within the group still remain confused. This paper is the second in a series revising the hornwort species of Australia and is a foundation paper for the genus Phaeoceros in this region. Crand.-Stotl. (category 2) (family Phymatocerotaceae Duff et al.); Paraphymatoceros Hässel (category 3); and Phaeomegaceros Duff et al. (category 4) (subfamily Phaeomegacerotoideae Duff et al.). Hässel’s study highlighted the broad diversity of spore patterning within this group, and recent molecular results have confirmed the importance of spore characters as well as highlighting the importance of others such as chloroplast, pyrenoid, or tuber morphology. Historical Review After a comprehensive study of the hornworts, Proskauer (1951) circumscribed the genus Phaeoceros from the broadly defined Anthoceros on the basis mainly of the absence of internal schizogenous cavities in the thallus typically found in Anthoceros. However, characters considered of secondary importance included irregularly arranged antheridial jacket cells and yellow spores. Acceptance of the new genus was not universal and controversy surrounded its nomenclature until recently. The name Anthoceros has now been conserved for those elements that possess dark-colored spores and a cavernous thallus (Stotler & Crandall-Stotler, 2003). After Proskauer’s revisions for the genus Phaeoceros, a number of studies ensued. These included the studies of Hässel de Menéndez (1989) who recognized 23 species for North and South America. On the basis primarily of the patterns of the distal and proximal faces of the spores observed through scanning electron microscopy (SEM), she emphasized the importance of spore differences in the separation of species. She grouped the American species into four distinct categories on the basis of the patterns of the spore distal face: 1) spores with spines or baculae, for example, P. carolinianus (Michx.) Prosk. (Fig. 3.); 2) spores with large projecting verrucae, for example the spores of P. tenuis (Spruce) Hässel or P. pearsonii (M.A. Howe) Prosk. (Hässel de Menéndez, 1989); 3) spores with fine, low ornamentation, for example the spores of Phymatoceros bulbiculosus (Brot.) Stotler et al. (Crandall-Stotler et al., 2006); and 4) spores with depressions, for example the spores of Phaeomegaceros fimbriatus (Gottsche) Duff et al., (Hässel de Menéndez, 1989 as Phaeoceros fimbriatus Gottsche). These groupings were not given any taxonomic status by Hässel, but recent molecular studies have partially supported these categories, giving rise to three new genera, a new family, and a new subfamily: Phymatoceros Stotler, W.T. Doyle & 240 History of Australian Taxa The earliest record of an Australian hornwort was made by Lehmann and Lindenberg in 1832 describing Anthoceros adscendens and A. glandulosus (Lehmann 1832). Over the next 80 years, only 11 more taxa were added to the Australian records until the comprehensive publications of Stephani in 1917. He attributed 19 anthocerotes to Australia, of which eight were new to science and two species were new records for Australia. Of the 29 taxa recorded for Australia (many of which are yellow spored), only two species have been recognized for the genus Phaeoceros: P. laevis and P. carolinianus (McCarthy 2006). Scott and Bradshaw’s important foundational checklist of Australian liverworts (Scott & Bradshaw 1985) did not accept the generic rank of Phaeoceros. Instead they preferred to follow Jones’ (1958) and Schuster’s (1963) placement as a subgenus of Anthoceros. Molecular studies have subsequently supported Proskauer’s original split of Anthoceros into two distinct genera (Duff et al., 2004, 2007; Frey & Stech, 2005), and the genus Phaeoceros is universally accepted. A number of regional revisions of Phaeoceros have been published over the last two decades, including Japan, South East Asia, and islands of the Pacific (Hasegawa, 1984a, b, 1986a, b, 1991, 1993, 2002), New Zealand (Campbell, 1981a, b, 1982, 1993), North and South America (Hässel de Menéndez. 1989; Schuster 1992), and India (Asthana & Srivastava, 1990). However, since the prodigious publication of Stephani (1900–1924), no comprehensive revision of the hornworts for Australia has been undertaken. The aim of this paper is to determine the status of the yellowspored taxa previously published for Australia. Also included is the description of a new species, P. engelii named in celebration of John Engel’s 40 years of publications in the field of bryological studies. FIELDIANA: BOTANY Materials and Methods The type specimens of all yellow-spored taxa originally described for Australia were examined, including collections of Phaeoceros from all major Australian herbaria. Field collections were also made over a wide geographical range within Australia. Where mature sporophytes were present, spores were sampled for viewing with SEM. Air-dried spores were removed from capsules and mounted on double-sided sticky tape attached to aluminum stubs. Stubs were gold coated and viewed with either a Hitachi S-570 or a Jeol JSM 6400 SEM. Spores and pseudoelaters were also mounted in water for measurement and color information with subsequent permanent mounting in either Hoyer’s or Johnson Brite®. Both rehydrated herbarium specimens and live field collections were examined, sectioned, measured and drawn for gametophytic and sporophytic characters with the use of both compound and dissecting microscopes with attached drawing tubes. Habit and light microscope images of Phaeoceros were taken with a Nikon Coolpix 5000 digital camera. Colors of gametophytes were determined by the use of the Royal Horticultural Society Colour Chart (1995). Results Type specimens of all species were available and examined. Of the seven yellow-spored taxa originally described for Australia, six fell into one of either three distinct groupings corresponding to the three species: Phaeoceros carolinianus, P. evanidus, and P. inflatus. Unfortunately, of the remaining taxon, neither the lectotype nor the isolectotype of Phaeoceros tuberosus (Taylor) Prosk. that we have seen to date had mature sporophytes, though morphologically the gametophyte clearly falls at the very least within the order Notothyladales Hyvönen & Piippo. Speculation as to which genus it might fall under and the need to examine fertile type material has required us to leave P. tuberosus out of this paper at present. Tubers described for all four taxa in this paper are typical of those found in P. pearsonii (M. Howe) Prosk., which are ventral, subterminal, and without stalks. Descriptions are given of all three species, as well as of a new species, P. engelii. A list of distinguishing features is given in Table 1. Phaeoceros Prosk., Bull. Torrey Bot. Club 78(4): 346 (1951) ETYMOLOGY—From the Greek phaeo- (dark) and ceros (a horn), in reference to the dark coloring and shape of the mature sporophyte. TYPE—Phaeoceros laevis (L.) Prosk. A widely occurring genus in both the Northern and Southern hemispheres Phaeoceros consists of ca. 40 taxa, of which Phaeoceros carolinianus (Michx.) Prosk. and P. laevis are the most widespread species worldwide (Hässel de Menéndez, 1987; Schuster 1992). Distinguishing characters for the genus in Australia include smooth solid thallus, yellow spores, irregularly arranged jacket cells of the antheridia, and possession of tubers in some species. Phaeoceros carolinianus (Michx.) Prosk. Bull. Torrey Bot. Club. 78: 347. 1951 Basionym—Anthoceros carolinianus Michx. Flora Boreali-Americana 2: 280. 1803. Type: USA. Carolina inferiori, herb. Camus, herb. Richard (holotype in PC). Synonyms—Anthoceros australiae Beauv. ex Steph. Spec. Hepat. 6: 571 (1924) syn. nov. Type: Australia, New South Wales, F. v. Mueller (as A. crispus) (lectotype G!). Anthoceros brotheri Steph. Hedwigia 32: 141 (1893) syn. nov. Type: Australia, Queensland, Brotherus 859 (lectotype in G!). Anthoceros communis Steph. Bull. Herb. Boissier 5: 86 (1897). Type: Japan, Akita, Faurie 1484 (lectotype in G!) NSW 261411. Anthoceros multicapsulus Steph., Spec. Hepat. 5: 991 (1916) syn. nov. Type: Lord Howe Island. (lectotype in G!). Thallus transparent, yellow-green to dark green (RHS Colour chart 135D; 137B,C, and D; 144B) growing on soil or rock. Plants small to medium in size, up to 20 mm in length and 15 mm in width, forming fans, rosettes, patches or mats, adhering to bare soil or rock. Furcate to irregularly branched, frequently with ventral unstalked tubers becoming broad and flat, full of starch granules. Thallus solid, 8–12 cells thick in transverse section, varying from biconvex to planoconcave to concave-convex. Dorsal epidermal cells quadrate to hexagonal, 17–83 × 17–48 µm. Internal cells 26–82 × 26–70 µm. Ventral clefts observable sometimes and flanked by two cells. Nostoc colonies scattered through ventral half of thallus, appearing as dark dots. Rhizoids ventral, hyaline, or pale brown. CARGILL AND FUHRER: PHAEOCEROS TAXONOMIC STUDIES 241 Monoicous, androecium with 2–5 antheridia per cavity, jacket cells irregularly arranged, 256 × 133 µm, stalk up to 38.4 µm long. Involucre erect, conical-cylindrical, up to 6 mm long, contracted at the mouth, 5–7 cells thick in transverse section. Sporophyte capsule up to 80 mm long, exserted, opening by two valves becoming twisted with drying, with well-developed columella, becoming yellow and then dark brown with age from the apex down. Assimilative layer 4–5 cells thick and sporogenous layer of two rows of spores. Epidermal cells of capsule elongated rectangular, 99–227 × 16–22.5 µm, walls becoming thickened with maturity, stomata present in the capsule wall. Spores bright yellow, rounded-tetrahedral equatorial diameter 36–43 µm. Distal face covered with numerous spines, proximal face finely rugose with button-shaped verrucae confined to the center of each triradiate face. Proximal face with a distinct triradiate mark, covered in a sculpturing of small bacillar and button-like papillae along its length. Pseudoelaters thin walled, up to 5 cells in length, frequently branched, 43–199 µm long and 9.5–22 µm wide, pale brown. ETYMOLOGY—The species epithet “carolinianus” refers to the location of the type collection, which was originally collected in North (or ?South) Carolina, USA. DISTRIBUTION AND ECOLOGY—A ubiquitous species across Australia, it is typically found growing on bare soil, on and beside bush tracks, roadside banks and banks of waterways (Fig. 1a). AFFINITIES AND DIFFERENTIATION—Phaeoceros carolinianus (Fig. 2) is closely related to P. laevis, with many Australian collections identified as P. laevis; however, sexual condition and spore proximal patterns distinguish these two species. Phaeoceros carolinianus is monoicous and FIG. 1. Gametophyte and sporophytes of the four Australian species of Phaeoceros. (a) Phaeoceros carolinianus (Cargill & Fuhrer 841. Queensland); (b) Phaeoceros evanidus (Cargill & Fuhrer 875. Queensland. Millstream Falls NP); (c) Phaeoceros inflatus (Cargill & Fuhrer 475. Victoria. Warrandyte SP); (d) Phaeoceros engelii (Cargill & Fuhrer 1017. Victoria. Lower Glenelg NP, Moleside Crk.) Scale = 10 mm. 242 FIELDIANA: BOTANY FIG. 2. Phaeoceros carolinianus. (a) Gametophytes with sporophytes. Scale = 4 mm. (b) Antheridia illustrating the irregular arrangement of jacket cells typical of the genus. Scale = 100 µm. (c) Dorsal epidermal cells of thallus. Scale = 100 µm. (d) Transverse section (TS) of thallus. Scale = 100 µm. (e) Cells of thallus through TS section. Scale = 100 µm. (f) TS through basal section of sporophyte and involucre. Scale = 100 µm. (g) Internal cells of sporophyte; inv = involucre; sp = sporophyte. Scale = 100 µm. proximal verrucae numbers are low and confined to the central section of each triradiate face (Fig. 3). The type spores of P. laevis have verrucae covering each of the triradiate faces and it is dioicous (Proskauer, 1951; Hässel de Menéndez, 1987). Phaeoceros laevis has not been confirmed to occur in Australia, and is probably confined to the northern hemisphere. SPECIMENS EXAMINED—Australian Capital Territory: Head of Murray’s Gap, Bimberi Ra., Cotter River District, mud banks in swampy herb field, Schodde (AD 26972); Gladfield, Darling Downs, Gwyther 331871 (BRI); Bendoura Dam Rd., Brindabella Ra., 28 km SW of Canberra, Streimann (CBG 7804945); Little Collins Crk., Brindabella Ra., head of small shaded gully. Streimann 5281 (CBG 7804939); Botanic Gardens, Canberra, common on moist, shaded stream banks, Streimann (CBG 066486); Murray’s Beach, Jervis Bay, wet shaded cliff face above beach, Streimann 5032 (CBG 7892211); Bull’s Head, Brindabella Ra., on moist earth, on rock outcrop in Eucalyptus forest, Scott s.n. (2) (MUCV129). Lord Howe Island: Lord Howe Is. (MEL 1039116, 1039117, 1039126 & 1039127); 1 km E of King’s Beach at foot of Mt. Lidgbird, on bank of creek, Corrick 11049 (MEL 11049). New South Wales: Minyon Falls, 25 km NNE of Lismore, moist exposed rocks below falls, Streimann 6844 (CBG 7905590); Wilson’s Crk., 8 km W of Mullumbimby, on rocks beside stream, Bender 14 (CBG 7708512); Flat Rock Crk., North Shore, Sydney, wet banks, Whitelegge s.n. (MEL 1039092); Mossmans Bay, near Sydney, waterfalls, Watts 199 (as Anthoceros communis NSW 261411); Centennial Park, Sydney, Cheel 803 (as Anthoceros brotheri NSW 261409); between Mt. Kiera & Wollongong, moist soil, on the roadside, Coveny s.n. (NSW 261536); Gosford Rd. near Woy Woy, rocks by waterfall, Bessie 1/59 (SYD); Huntley Point, Barnard s.n. (SYD BARN 4.11.25); Somersby Falls, Na-Thalang s.n. (SYD O.N.T. 2.7.66(1)); Nadgee Fauna Reserve, between W Newtons Beach and Little River, on soil on bank of gully, Hewson s.n. (SYD HJH 18.4.65 (1)). Norfolk Island: Broken Bridge Crk., on continuously wet overhanging rock, Hoogland 6632 (CANB 77819). Queensland: Mooloolah River, 2 km SW of Mooloolah, Moreton District, on peaty detritus among rocks in bed of running stream, Windolf 124 (BRI 331874); Warrumbah Crk., Carnavon Nat. Park, narrow shaded gorge with scattered shrubs and trees, on semi-exposed rocks in creek, among Lunularia, Steimann 52188 (CBG 9312854); Murphey’s Crk., 16 km NE of Toowoomba, side of creek on rocks, dry sclerophyll forest, Streimann 370 (CBG 051234); Kin Kin Crk., 19 km NNW of Tewantin, creek bank, sandy loam, Telford 4341 (CBG 7902323); Johnstone River track near Sutties Crk., Tully, on roadside bank, tropical rainforest, Scott s.n. (MELU 6743); Blencoe Crk., Kiirama State Forest, Cardwell, riverbank, cleared tropical rainforest, Scott s.n. (MUCV 6924) Millstream Falls, Ravenshoe, on bare soil at side of track, Cargill & Fuhrer (MUCV 7991); Wright’s Crk. Rd., Lake Eacham Nat. Park, on roadside bank, Cargill 55103 & 55104 (MUCV 7980 & MUCV 7981); Greene’s Falls, S of Mt. Glorious, in rainforest, on wet rocks at top of waterfall, Smith & Tindale H62 (NSW 261553); Millstream Falls, Ravenshoe, Watts s.n. (NSW 261550). South Australia: Back Valley, off Inman Valley, Southern Lofty Region, Cleland 51 (AD 5889); Back Valley Southern Lofty Region, Cleland s.n. (AD 6000); Ashbourne Area, Southern Lofty Region, CARGILL AND FUHRER: PHAEOCEROS TAXONOMIC STUDIES 243 FIG. 3. SEM micrographs of spores of Phaeoceros carolinianus. (a, c) Distal face; (b) proximal face; (d, f) detail of proximal micro-ornamentation; (e) close-up of micro-ornamentation of distal face. Scales: (a–c) 10 µm; (d–f) 1 µm. [a–f from Cargill & Fuhrer 490, Australia. Victoria. S E Gippsland, Costicks Weir, Mundic Crk.] growing on spongy ground near Juncus sp. and Callitrix stagnalis, soakage start of creek, Murfet 668 (AD 27625); Square Waterhole near Mt. Compass, in a swamp, Symon s.n. (AD 6923). Tasmania: Norfolk Island, 244 Robinson (MEL 1039122). Victoria: Black Spur, Bastow s.n. (MEL 1039095); Buffalo Ra. F. von Mueller s.n. (MEL 1028292); Spring Gully at Maliuns, 52 km N of Orbost on the Bogong Hwy. Thiele 709 (MELU 2452). Western FIELDIANA: BOTANY Australia: Worriga Gorge, Drysdale River Nat. Park, on wet sandstone rocks in shaded part below waterfall, George 14100 (MEL 1023878); Sandy Crk., King Leopold Ranges, Kimberleys, in peaty creek bed, Scott s.n. (MELU 789); Galvans Gorge, West Kimberleys, damp earth among ferns, under fall of water, Willis s.n. (MELU 547). Phaeoceros evanidus (Steph.) Cargill & Fuhrer comb. nov. Basionym—Anthoceros evanidus Steph., Spec. Hepat. 5: 990 (1916). Type: Australia, Port Denison, W.W. Birch (lectotype in G!). Thallus pale transparent yellow-green to green (RHS Colour Chart 143C, 145B), delicate, growing in rosettes on bare moist soil patches. Plants small up to 15 mm long and 2.4–15 mm wide, from single lingulate thallus to ± fan-shaped branched thallus with overlapping lobes originating from a persistent, narrow strap posteriorly, furcately branched. Margins irregularly crenulate to ± entire, sometimes lateral margins curving upward becoming canaliculate. Thallus solid, but some plants occasionally with large inflated epidermal cells giving the plant a “quilted” appearance typically seen in members of the Anthocerotaceae s. str. Thallus concave-convex to plano-convex in transverse section, 7–11 cells thick. Dorsal epidermal cells quadrate to hexagonal, 28–92 × 19–53.3 µm. Cells with single chloroplast and pyrenoid. Some populations with dorsal stalked obpyriform to obovoid-shaped propagules (583–1,000 × 473–500 µm). Surface of propagules crenulate because of bulging epidermal cells. Stalk up to 1000 µm long and 500 µm wide, composed of rectangular cells with single orange chromoplast. Plants sometimes with ventral unstalked tubers. Ventral clefts flanked by two cells at apical notch. Nostoc colonies scattered through thallus, appearing as dark dots. Rhizoids hyaline along ventral surface. Monoicous, androecia scattered over dorsal surface, 1–4 antheridia per cavity, spherical yellow-orange, on short stalks, 115–132.5 × 82.5– 100 µm, jacket cells irregularly arranged. Involucre erect and cylindrical, contracted at the mouth, 1.2–2.8 mm long, 4–10 cells thick. Capsules erect, 5–12 mm long, exserted, splitting by two valves, assimilative layer 4–7 cells thick in transverse section, sporogenous layer 2 cells thick, with welldeveloped columella. Epidermal cells of capsule elongate rectangular (66–143 × 8.5–19.2 µm) punctuated with stomata (33 × 21 µm). Spores bright yellow, rounded-tetrahedral, with smooth border, equatorial diameter from 32–49 µm. Distal surface with numerous coarse, wart-like protuberances, frequently coalescing in the center of the face, with smaller scattered verrucae in between larger protuberances, equatorial girdle smooth. Proximal surface with distinct triradiate mark covered in small spherical to baculate papillae on either side of a narrow, smooth dehiscence line. The three triradiate faces of the proximal surface covered with distinct button-like verrucae. A distinct shallowly papillate margo encircles the entire proximal face. Pseudoelaters 1–3 cells, 36–164 × 9.5–33 µm, pale brown, thin-walled, occasionally branched. ETYMOLOGY—The species epithet “evanidus” in Latin means vanishing. Stephani was probably referring to the ephemeral nature of this species. DISTRIBUTION AND ECOLOGY—This species is confined to the tropical northeastern region of Australia from the Atherton Tablelands of Far North Queensland to northern New South Wales. AFFINITIES AND DIFFERENTIATION—Possibly overlooked because of small size of plants (Fig. 1b), it is distinguished from both P. carolinianus and P. inflatus by its distinct spore patterning (Fig. 5). The spore distal face of the former species is covered in spine-like protuberances, whereas that of the latter species displays fewer, less coarse protuberances. Both species also lack the number of distinct button-like verrucae covering each of the triradiate faces. The proximal micro-ornamentation between verrucae is lacking in P. evanidus, whereas it is composed of interweaved vermiculae for both P. carolinianus and P. inflatus. It is also distinguished from P. inflatus by its monoicous sexual condition (Fig. 4). SPECIMENS EXAMINED—New South Wales: Duck Creek Rd., 22 km WNW of Bulahdelah, disturbed clearing beside road at edge of forest dominated by Eucalyptus. Curnow 3304 (CBG 9313538); New South Wales. Leichardt s.n. (MEL 1039120). Queensland: Port Denison [Qld]. W.W. Birch s.n. (lectotype G 2107/5); Charleys Creek, 18 km NNE of Proserpine, poor, scrubby forest on rocky hillside, on soil. Curnow 1160 (CANB 753174); Millstream Falls NP, on bare soil on side of walking track down to lookout Cargill & Fuhrer 875, 876 (CANB 753175, CANB 753176); Queensland. Bowmann (MEL1039123) Millstream Falls, Ravenshoe, on bare soil on side of walking track. Cargill 55100 + CARGILL AND FUHRER: PHAEOCEROS TAXONOMIC STUDIES 245 FIG. 4. Phaeoceros evanidus. (a–b) Gametophytes with sporophytes. (a) Scale = 4 mm; (b) two plants, scale = 3 mm; (c) gametophytes with sporophytes and propagules, scale = 5 mm; (d) propagules (pr), scale = 100 µm, and epidermal cells of propagules; (e) transverse section through thallus displaying a concaveconvex shape, scale = 100 µm, and internal cells of thallus; (f) TS through sporophyte (as = assimilative layer, col = columella, te = tetrads); (g) dorsal epidermal cells of gametophyte thallus. All cell illustration scales = 100 µm. dupl. (MUCV 7986 & MUCV 7987); Broadwater Forest Park, W. of Ingham, Stone s.n. (MELU 1084) Phaeoceros inflatus (Steph.) Cargill & Fuhrer comb. nov. Basionym—Anthoceros inflatus Steph., Spec. Hepat. 5: 990. 1916. Type: Australia, New South Wales, Uralba, W.W.Watts 391 (lectotype in G!, isolectotype in NSW!). Thallus bright green to yellow-green to olive green (RHS Colour Chart: males 144A, B; females 143B), becoming brown when dried, growing on soil or rocks in mats or rosettes. Female plants 246 small to medium in size, up to 20 mm in length and 5 mm in width, irregularly branched, apices of branches spathulate. Thallus solid, 8–9 cells thick, usually concave-convex, fleshy. Margins of plants entire, undulate or irregularly crenulate. Dorsal epidermal cells rectangular to hexagonal, 28–79 × 20–56 µm. Plants frequently with ventral unstalked tubers. Ventral clefts not observed. Nostoc colonies scattered through the ventral portion of thallus as dark dots. Rhizoids ventral and hyaline or pale brown. Dioicous, male plants smaller, up to 10 mm long and 2 mm wide. Androecium with (1–)2–3 antheridia per cavity, ovoid to spherical, white to bright yellow, sunken into thallus, 163–250 × 133–150 µm on short stalks, cells of jacket irregularly arranged. Involucres erect cylindrical, up to 4 mm long. Capsules up to 40 mm long, one per involucre, splitting on either one or two sides by way of two valves, frequently remaining attached at apex, stomata scattered throughout epidermal layer, 61–77 × 41–51 µm, assimilative layer 5–7 cells thick in transverse section, sporogenous layer 1–2 tetrad layers thick, with well-developed columella. Epidermal cells of capsule rectangular to hexagonal and elongate 59–187.5 × 15–30 µm. Spores yellow to yellow-grey, 37.5–56.5 µm in diameter, rounded-tetrahedral. Distal surface with irregularly scattered, coarse protuberances, variable in shape crowned with one to several blunt triangular-shaped, wart-like or tuberculate papillae, never spine-like, intervening surface wrinkled, finely papillate or nearly smooth. Proximal surface with distinct, broad triradiate mark, entire face surrounded by a distinct cingulum. Triangular faces, flat or concave, with fine interwoven vermiculate-like patterning on surface, verrucae confined to central section of each face and can be distinct or indistinct. Pseudoelaters pale brown to dark brown at maturity, transparent, thin-walled and 1–4 celled, (41–)46–297 µm in length and 7.5–28(–38.4) µm in width, linear or branched. ETYMOLOGY—The species epithet “inflatus” arises from Stephani’s observation of an inflated assimilative layer within the capsule resulting in a bulging involucre (see Stephani’s Icones Hepaticarum). DISTRIBUTION AND ECOLOGY—A relatively common species among the Australian anthocerotes, extending down the eastern area of Australia from Queensland down to Victoria. FIELDIANA: BOTANY FIG. 5. SEM micrographs of spores of Phaeoceros evanidus. (a) Distal face; (b) one of the triradiate sections of proximal face; (c) proximal face and equatorial view of spores; (d) group of spores and pseudoelaters. All scales = 20 µm, except (b) = 10 µm. [a–d from type of Anthoceros evanidus (G)] Typically found growing on moist soil of banks and pathways, often in shaded habitats. AFFINITIES AND DIFFERENTIATION—Stephani described this species from a specimen sent to him by Rev. W. W. Watts from the Richmond River at Uralba, NSW (Stephani, 1916). His description of this taxon is somewhat confusing, in that he has described the thallus “cavernosa” which is typical of Anthoceros s. str.; yet, he is clear that the spores are pale yellow and minutely papillate. Examination of the type specimen confirms its placement within the genus Phaeoceros with possession typically of a solid thallus, irregularly arranged jacket cells of the antheridia and yellow spores. It differs from both P. carolinianus and P. evanidus in its dioicous sexual condition and irregular coarse protuberances topped by smaller, irregular-shaped papillae observed on the distal face of the spores (Figs. 1c, 6, 7). SPECIMENS EXAMINED—Australian Capital Territory: Head of Murray’s Gap, Bimberi Range, on mud banks in swampy herb. field, Schodde 1302 (NSW 261525 & CANB 108656). New South Wales: Richmond River, Uralba, on ground, hill top. 23 September 1901. W. W. Watts n. 371 (lectotype G! ; isotype NSW 261462!); Hurstville, near Sydney, on earth, Whitelegge (NSW 259158); North Shore, Sydney, Whitelegge (NSW 259155); NSW 261701; Hurstville near Sydney, Whitelegge (MEL 1039090); North Shore, Sydney. Whitelegge s.n. (MEL 1039191). Queensland: Flinders River (MEL 1039114). Victoria: Near Dimboola. Willis s.n. (MEL 1039091); end of forest road to Hogan’s Flat, above Lerderderg River Gorge (and opposite Mt. CARGILL AND FUHRER: PHAEOCEROS TAXONOMIC STUDIES 247 Blackwood), Blackwood Ranges. Willis s.n. (MEL 1030295); Anderson Inlet, (MEL 1039119); Heathermere Siding Rd., Heathermere, Cargill & Fuhrer 17733 (MELU 6368); Yeodene, SE of Colac, Beauglehole 1965 (MEL 1043437); Belgrave Sth camping ground, on moist clay bank beside lake, Scott s.n. (MUCV 367); Whitehills Dam, Rushworth, Scott s.n. (MUCV 4787); Yarra GlenYea Rd. (west side), on damp clay bank, under trees, Scott s.n. (MUCV 4328); Main Ridge, Mornington Peninsula, on clay soil in Eucalyptus obliqua forest, Scott s.n. (MUCV 2561); Scott’s [farm] block, Frazer River, King Island, Scott s.n. (MUCV 4022); Jumping Creek, Warrandyte SP, carpark, on bare soil at side of road, Cargill & Fuhrer 55014, 55015, 55030 (MELU 7917, 7922, 7916); Silverband Falls, Grampians Nat. Park, at base of walking track on earth bank, Cargill & Fuhrer 55022, 55025, 55027, 55028, 55029.(MUCV 7906, 7911, 7913, 7914, 7915); Mt. Victory Rd. near Hall’s Gap, Grampians Nat. Park, rocky alcove on side of road in deep shade, Cargill & Fuhrer 55020 (MUCV 7903). Phaeoceros engelii Cargill & Fuhrer sp. nov. FIG. 6. Phaeoceros inflatus. (a–c) Female gametophytes (No = Nostoc colonies), scale = 3 mm; (b) scale = 4 mm; (c) scale = 5 mm (vt = ventral tuber); (d) dorsal epidermal cells, scale = 100 µm; (e) TS through thallus, scale = 100 µm; (f) internal cells of thallus, scale = 100 µm; (g) TS through sporophyte (ep = epidermal cells, as = assimilative layer, sp = spores; el = pseudoelaters); (h) mature spore and pseudoelaters, scale = 100 µm. Type—Australia. Victoria. Lower Glenelg National Park. Kentbruck Rd. bridge over Moleside Crk. 11 October 2006. Cargill & Fuhrer 1016 (Holotype CANB). Ab omnibus aliis speciebus Phaeoceratis propagulis numerosis habens praeter margines thalli, coloniis nostocinis ventralibus tumescentibus, et propriis eminentia trabeculatis in pagina distali sporarum, differt. FIG. 7. SEM micrographs of spores of Phaeoceros inflatus. (G): (a) Distal face; (b) proximal face. Scale = 20 µm. [a, b from type of Anthoceros inflatus (G)] 248 FIELDIANA: BOTANY Thallus yellow-green (RHS Colour Chart 146A), but appearing dark green at habitat because of deep shade and becoming black-green when dried, growing on soil or rocks in mats close to edge of creek or on rocks in creek or on banks of creek. Female plants up to 60 mm long and up to 11 mm wide, irregularly furcate branching, frequently with young lateral branches forming on mature thallus, lobes lingulate at apices. Thallus solid, 8–13 cells thick, plano-convex to concave-convex in transverse section, fleshy. Margins of thallus irregularly crenulate, with some populations possessing margins fringed with deciduous propagules. Dorsal epidermal cells quadrate to hexagonal, 25–57.5 × 22.5–37.5 µm. Thickening of ventral apices observed in plants not unlike the ventral unstalked tubers typically seen in this genus. No ventral clefts observed. Nostoc colonies scattered through thallus becoming spherical and bulging significantly from ventral surface with maturity. Rhizoids ventral and pale brown. Subsequent maturation of the sporophytes and examination of the spores placed it squarely in the genus Phaeoceros. AFFINITIES AND DIFFERENTIATION— Collections made in later years revealed plants with numerous deciduous propagules growing almost like a fringe around the margins of the thallus (Figs. 1d, 8a). They are also found growing in patches on the dorsal and ventral surfaces of the thallus. Not infrequently, it would appear that some propagules remained attached to the parent thallus and grow to produce secondary branches. Similar structures were also observed and described by Howe for the species Anthoceros vegetans M. Howe (Howe, 1934) and by Stephani for the Chilean species P. propaguliferus (Steph.) Prosk. (Stephani, 1917). Also peculiar to this species is the morphology of the mature Nostoc colonies, which bulge out as a relatively large hemispherical growth from the ventral surface of the thallus (Fig. 8c), unlike the typical colonies, Dioicous, male plants smaller, up to 21 mm long and 4 mm wide. Androecium with 2 antheridia per cavity, ovoid, pale yellow, sunken into thallus, 175–325 × 150–240 µm, on short stalks, jacket cells irregularly arranged. Involucres erect, cylindrical, flaring at base up to 5 mm long, 5–8 cells wide in transverse section. Capsules up to 30 mm long, one per involucre, exserted, becoming blackish brown at tips with maturation of spores, opening by two valves, 6–8 cells thick in transverse section, stomata scattered throughout epidermal layer, 72.5–90 × 42.5–60 µm. Epidermal cells of capsule rectangular to hexagonal and elongate 82.5–170 × 12.5–27.5 µm. Spores yellow, 38–56.3 µm in diameter, rounded-tetrahedral. Distal surface covered in short irregular trabeculate protuberances frequently coalescing to form irregular lamellae. Proximal surface covered in numerous irregular-shaped verrucae. Pseudoelaters pale brown at maturity, transparent, thin-walled and 1–4-celled, linear or branched, 67–223 µm in length and 15–23 µm in width. ETYMOLOGY—Named for Dr. John Engel to commemorate his 40 years in hepaticology. DISTRIBUTION AND ECOLOGY—This species is known only from one location beside and within a creek in the Lower Glenelg National Park. Its habitat preference is very similar to that of most Megaceros populations in relatively shady conditions near running water. In fact, when first collecting this hornwort, we had thought that it was indeed a Megaceros. FIG. 8. Phaeoceros engelii. (a) Female gametophytes with marginal propagules, scale = 10 mm; (b) male gametophytes, scale = 10 mm; (c) TS through thallus illustrating Nostoc colony bulging from ventral surface, scale = 3 mm; (d) internal cells of thallus, scale = 100 µm; (e–f) TS through sporophyte and involucre, (e) scale = 3 mm, (f) scale = 100 µm (inv = involucre, sp = sporophyte, te = tetrad, col = columella; (g) spore and pseudoelaters, scale = 25 µm. CARGILL AND FUHRER: PHAEOCEROS TAXONOMIC STUDIES 249 which remain small and well embedded in the ventral portion of the thallus (Fig. 6e). This phenomenon has not typically been observed in other Australian species of Phaeoceros. The sexual condition and spore distal pattern (Fig. 9) distinguish this species from both P. carolinianus and P. evanidus, both of which are monoicous, whereas P. engelii is dioicous. Also, the more robust habit of the populations of P. engelii (Figs. 1d, 8) separates it immediately from the more diminutive P. evanidus. It differs from P. inflatus in its possession of numerous propagules, but where these are not apparent, it differs significantly in the spore distal patterns. The spores of P. inflatus, while displaying protuberances from the distal face, differ in their micro-morphology. Phaeoceros engelii displays trabeculate protuberances (Fig. 9), whereas P. inflatus displays typically fewer, coarser protuberances that are often crowned by another layer of spine-like or wart-like papillae (Fig. 7). SPECIMENS EXAMINED—Victoria: Kentbruck Rd. bridge over Moleside Crk., Lower Glenelg NP. Cargill & Fuhrer 1016 (Holotype CANB); Cargill & Fuhrer 363 (CANB 654152); Cargill & Fuhrer 1015, (CANB); Cargill & Fuhrer 1017 (CANB). Key to the Species 1. 1. 2. 2. 3. 3. Plants monoicous …...........................………..……..........................………….............…………...2 Plants dioicous ….............................……………..........................………….................…………...3 Plants robust, up to 20 mm long, without propagules, widespread distribution, spores with spinelike protuberances over distal face ..…..........................................…..…….Phaeoceros carolinianus Plants delicate, up to 15 mm long, sometimes with dorsal propagules, restricted in distribution to tropical and subtropical areas, spores with large, wart-like, coalescing protuberances, proximal surface with distinct button-like verrucae covering each triangular face...........Phaeoceros evanidus Plants dark green, often with propagules along margins of thallus and with bulging ventral Nostoc colonies, restricted distribution, spore distal face covered in short trabeculate protuberances frequently coalescing to form short lamellae .......................................................Phaeoceros engelii Plants bright green, without propagules, Nostoc colonies not bulging, widespread, spore distal face with scattered irregular protuberances .................................…...………… Phaeoceros inflatus TABLE 1. Phaeoceros species Size of plants P. Up to carolinianus 20 × 15 mm P. evanidus Up to 15 × 2– 15 mm P. inflatus P. engelii 250 Females; up to 20 × 5 mm males up to 10 × 2 mm Females up to 60 × 11 mm; males up to 21 × 4 mm List of distinguishing characters of four Australian species of Phaeoceros. Color Yellowgreen to dark green Pale yellowgreen to green Bright green to yellowgreen to olive green Yellowgreen to green Tuber type Propagules Nostoc colonies No. of Sexual antheridia condition per cavity Unstalked, Absent ventral marginal Embedded Monoicous in thallus, not bulging 2–5 Unstalked, Dorsal ventral marginal Embedded Monoicous in thallus, not bulging 1–4 Unstalked, Absent ventral marginal Embedded in thallus, not bulging Dioicous (1–) 2–3 Unstalked, Marginal, ventral ventral marginal and dark dorsal Ventral and bulging Dioicous 2 Spores Yellow, distal face spiney Yellow, distal face wart-like Yellow, distal face coarsely papillate Yellow, distal face trabeculate forming lamellae FIELDIANA: BOTANY FIG. 9. SEM micrographs of spores of Phaeoceros engelii (a, c) distal face; (b, d) proximal face; (e) detail of micro-ornamentation of distal face; (f) detail of micro-ornamentation of proximal face. Scales (a–d) 10 µm, (e–f) 1 µm. [a–f Cargill & Fuhrer 363. Victoria. 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