New species of Gossia N.Snow & Guymer and Rhodomyrtus (DC.) Hassk. (Myrtaceae) from Papua New Guinea Neil Snow Summary Snow, N. (2006). New species of Gossia N.Snow & Guymer and Rhodomyrtus (DC.) Hassk. (Myrtaceae) from Papua New Guinea. Austrobaileya 7(2): 325-340. Two new species each of Gossia N.Snow & Guymer (G. scottiana N.Snow, G. longipetiolata N.Snow) and Rhodomyrtus (DC.) Hassk. (R. kaxveaensis N. Snow, R. mengenensis N. Snow) in the myrtle family (Myrtaceae) are described from Papua New Guinea. All four species are known only from the type collections. Each species is considered “Data Deficient” following IUCN guidelines, and all are probably narrowly distributed. The new species of Gossia bring to six the number of species in this genus now known from the island of New Guinea. The newly described species in Rhodomyrtus, along with another undescribed species in preparation from Papua New Guinea, suggest that ten species of Rhodomyrtus occur on New Guinea. The new species of Rhodomyrtus have brochidodromous nervation, relatively long petioles, and narrowly elliptic to elliptic leaves. Included are photographs of the type specimens, a distribution map of the new species, separate keys to species of Gossia and Rhodomyrtus from Malesia, and a discussion of the biogeography of Gossia and Rhodomyrtus. Key Words: Myrtaceae, Myrtineae, Gossia longipetiolata, Gossia scottiana, Rhodomyrtus kaweaensis, Rhodomyrtus mengenensis, new species, Malesian flora, Papua New Guinean flora. New Guinean flora, Australasian flora, biogeography, conservation, identification keys. Archbold Expeditions N.Snow, School of Biological Sciences, University of Northern Colorado, Greeley, CO 80639, USA Email: [email protected] Introduction During the examination of previously Materials and methods indetermined material of Myrtaceae on loan Each of the newly described species was to the author for several revisionary projects recognized as being distinct only after and a graduate thesis (Csizmadi 2006) two comparison against specimens representing specimens each of Gossia N.Snow & Guymer all known taxa in their respective genera. and Rhodomyrtus (DC.) Hassk. from Papua Additional duplicates of Gossia were New Guinea could not be assigned to known searched for by the author in some herbaria, species. In light of the recent revision of and he was assisted by colleagues in several Gossia from Australia (Snow et al. 2003), other herbaria (see Acknowledgements) who the transfer of several Malesian species of kindly searched for more duplicate material Myrtus L. and Austromytrus (Nied.) Burret of the new species of Rhodomyrtus. Each of into Gossia (Snow 2005), and the author’s the new species is diagnosably distinct from nearly completed treatment of Gossia for New congeners following species concepts and Caledonia (Snow in prep.), it became clear species criteria outlined previously (Snow that the two species of Gossia represented 1997; Snow et al. 2003). The descriptive undescribed taxa. Because the new species information provided for each species varies of Rhodomyrtus described herein were somewhat given the limited material available recognized as such relatively late during for study and because differing amounts of preparation of the thesis (Csizmadi 2006), information are contained on the labels of the they are described here. specimens themselves. Taxonomy Gossia scottiana N.Snow, species nov. Accepted for publication 23 August 2006 similis G. longipetiolatae a qua floribus 5- merous, petiolis brevioribus, laminis foliorum 326 Austrobaileya 7(2): 325-340 sine glandibus manifests, et nervo medio adaxiali prominente differt. Typus: Papua New Guinea. Western Province: Fly River, 528 mile camp, May 1936, L.J. Brass 6766 (holo: L [photo, GREE]; iso: A, BRI, CANB). Tall slender trees, to unknown height. Bark smooth, thin, bright brown with hard brown wood beneath. Branchlets rounded, brownish- grey, smooth or somewhat flaking, glabrous, lacking evident oil glands. Leaves opposite, coriaceous, entire, concolorous, matt above and below. Stipular hairs ([Snow et al. 2003: 6-7], “acicular appendages” of some authors [e.g., Holst 2002]) not evident. Petioles 2-4.5 mm long, flat above. Leaf venation . Map 1 Distribution of Gossia scottiana m. pinnate; blades elliptic, 65-125 x 30-45 mm, G. longipetiolata • ,Rhodomyrtus kaweaensis A, and base rounded to cuneate, apex acuminate; R. mengenensis (cid:9733). adaxial and abaxial surfaces glabrous and lacking evident oil glands; adaxial midvein the species was growing at 80 m elevation in flush to somewhat raised; secondary and rainforest. Rand & Brass (1940: 368) report intramarginal veins indistinct to prominent. the ridges of this area as having reddish clay Flowers solitary, terminal, anthopodia and soils containing rounded or angular pebbles metaxyphylls absent (see Briggs & Johnson of quartz. The general vegetation of the area [1979] for specialized terminology regarding consisted of a very tall rainforest heavy with inflorescences), other features unknown. epiphytes (Rand & Brass 1940). Additional Peduncles rigid, 4.5-17 mm long, glabrous. details regarding the vegetation are presented Bracteoles and flowers unknown. Hypanthium in Brass (1938). in fruit densely covered with small glands; sepal lobes 5, glabrous, 1.5-2 mm long, apex Phenology: Flowering and fruiting in May, broadly rounded, persistent and erect in fruit. but likely fruiting well into June given that Fruits, globose, 10-12 mm long (dry; the label young fruits occur on some of the duplicates. indicating “up to 1.7 cm” when presumably For example, the specimen at BRI has just fresh), black (dried). Seeds rounded, testa finished flowering and has young fruits. hard, embryo circinnate. Figs. 1 & 2. Diagnostic attributes: Leaves elliptic; oil Presently known only from the type glands on blades not visible on dried material; collection. adaxial midvein of leaf raised; secondary and tertiary veins of leaf prominent above and Distribution and habitat: The Fly River 528 below; flowers 5-merous. camp of the Archbold Expedition, the location of the type collection, was located far inland Affinities: Among species of the genus near Macrossan Island at a point where the from New Guinea and on the basis of leaf Fly River makes a sharp bend (Rand & Brass morphology Gossia scottiana most resembles 1940). From an accompanying map in Rand & G. longipetiolata. However, G. scottiana Brass (1940), it appears the camp was about 15 has much shorter petioles, lacks evident air-kilometres southwest of Palmer Junction oil glands on the leaf, and has pronounced Camp, which is in the Western Province of secondary and tertiary veins on both laminar Papua New Guinea. This general region is surfaces. Among Australian species the downstream from where the Fly River meets gross morphology of G. scottiana somewhat the Palmer River at approximately c. 6°S resembles G. grayi N.Snow & Guymer (Snow and 141.5°E (Map 1; F.Lohrer, pers. comm. et al. 2003). However, G. scottiana has 5- 2005). The local topography is hilly (Rand merous flowers, a slightly raised midrib on the & Brass 1940), the specimen label indicating adaxial leaf surface and leaf surfaces lacking Snow, New species of Gossia & RJhodomyrtus 327 ^Holotvpe^ Isotype Lcctotype (foaiu scotftenc, hi' £fs, not), itirjr. Del. R Snow /? 2005 GnsSk [fn./lor*. 1* A) s/. wtWM* rt -So- 2< det. N. Sn< r. Nonhcm Colorado (GREE) rjWi*4bv wJUW tf/T, „t« of P«p»« (British New GuW.«), collect ell by the IBM Fly nr Expedition of tlie American Museum of Natural History, Mr, linn] Archbold, lender. DUIributed by ihc Arnold Arboretum rtu3 Fig. 1. Holotype specimen of Gossia scottiana (L.J.Brass 6766 [L]). evident oil glands. In addition, G. grayi lacks the latter has a more deeply channeled petiole, the raised secondary and tertiary veins on the moderately to densely glandular leaves, and leaves. G. scottiana also resembles to some lacks the pronounced attenuated leaf apex of degree the widespread Australian species G. scottiana. The description from the type G. bidwillii (Benth.) N.Snow & Guymer, but specimen label indicates “with conspicuous 328 Austrobaileya 7(2): 325-340 Isotype Lectotype (foaia s CoH~)<knc, M*£n**> « Xf>. riotf. hr Of' Det, N. Snow /r (^kc2005 University of Northern Colorado {GREE) Fig. 2. Close up of fruits on holotype of Gossia scottiana. bright brown, v.[ery] thin bark and hard brown Etymology: The specific epithet honours wood”, suggesting the species may be related Dr. Andrew John Scott (1950-) for his to members of the genus from Australia known important contributions to our understanding commonly as the “python barks” (Snow et al. of the berry-fruited genera of Myrtaceae (pro 2003), such as G. bidwillii and G. acmenoides parte, Scott 1978a,b, 1979a,b, 1980a,b, 1984, (F.Muell.) N.Snow & Guymer. 1985, 1990). Notes: The placement of this taxon in Gossia Gossia longipetiolata N.Snow, species nov. is supported in part by a detailed pencil floribus 4-meris; petiolis 7-10 mm longis; illustration of a circinate embryo on the laminis foliorum glandibus densis in quoque isotype from A, which appears just to the left pagina, nervo medio adaxiali piano. Typus: of the collection label. Presumably drawn Papua New Guinea: Western Province: by Merrill, the drawing reflects the coiled Tarara, Wassi Kussa River, December 1936, embryo that in part diagnoses Gossia from L.J.Brass 8588 (holo: L [photo, GREE]; iso: related genera (Snow et al. 2003). The hard A, n.v.' BO, «.v., BRI, CANB). testa of seeds in the fragment packet and other Slender trees 4-5 m tall. Bark smooth, thin, aspects of the fruit confirm its placement brown to grey. Branchlets rounded, light in Gossia. This same specimen evidently was seen and cited by Landrum (1988: 121; brown, smooth to slightly flaky, glabrous, misspelled therein as Bass rather than Brass) oil glands common but indistinct. Leaves while discussing embryo types as part of a coriaceous, venation pinnate. Stipules not revision of the neotropical genus Myrteola evident. Petioles 7-10 mm long, somewhat O.Berg. Additional material is needed to channeled above. Leaf blades elliptic, 75-120 more fully characterize the inflorescence, x 33-55 mm, base cuneate, apex acute to bracteoles, flowers (which are unknown) and acuminate. Adaxial and abaxial leaf surfaces fruit. matt, glabrous, with dense covering of oil Snow, New species of Gossia & RJhodomyrtus 329 glands. Adaxial midvein flush. Secondary in fruit. Flowering material unknown. and intramarginal veins of abaxial surface Hypanthium in fruits 4-merous, 1-1.5 mm indistinct to more or less prominent. long, upper surface sparsely sericeous, lower Inflorescence terminal or lateral, monads or surface glabrous, held more or less erect in few-flowered racemes, solitary or paired in leaf fruit. Fruits subglobose to globose, rounded axils. Anthopodia and metaxyphylls lacking. at base, 5-8 x 5-8 mm, glabrous, dark blue- Peduncles rigid, 4-18 mm long, glabrous. black at maturity. Figs. 3 & 4. Bracteoles two, linear, scale-like (lacking Known only from the type collection. midrib), 0.5-1 mm long, <0.5 mm wide, glabrous, persistent or (mostly) deciduous Fig. 3. Holotype specimen of Gossia longipetiolata {L.J.Brass 8588 [L]). 330 Austrobaileya 7(2): 325-340 Fig. 4. Close up of fruits on holotype of Gossia longipetiolata. Distribution and habitat: The type locality Phenology: Known in mature fruit (Map 1) occurs on the coastal lowlands of the from December; presumably flowering Arafura Sea at the old village of Tarara on the approximately 4-6 weeks earlier. Wassi Kusa River (Rand & Brass 1940: 355). Diagnostic attributes: Petioles 7-10 mm Brass (1938) reports that Tarara is located long; oil glands dense on both leaf surfaces; about 55 km (35 miles) from the mouth of adaxial midvein of leaf flush; secondary veins the river and indicates that the region (at the of leaves visible but not raised on adaxial time) supported small communities of semi- surface; flowers 4-merous. nomadic agricultural residents. This general area forms the western boundary of Strachan Affinities: Among species of Gossia from the Island at approximately 9°S, 142°E, (F.Lohrer, island of New Guinea the leaf morphology pers. comm. 2005). Brass (1938) indicates the most resembles G. scottiana, but the dense country consists of a plain with low ridges oil glands of G. longipetiolata and longer that gradually increases in elevation further petioles immediately distinguish it from the inland. The climate of the area is said to be former. Using the “key for sterile specimens” markedly seasonal with the majority of rain for Australian species (Snow et al. 2003: occurring from December to April (Rand 34-35), G. longipetiolata would key out with & Brass 1940). The area is underlain by G. bidwillii, but it differs from that species by limestone and mostly covered with savanna, its longer petioles and acuminate leaf apices. but rainforest occurs along waterways in More details are needed about the flower and thin strips (Brass 1938; Rand & Brass 1940). inflorescence structure of G. longipetiolata The specimen label indicates the species as and a molecular-based study of the genus will being common in the underbrush of light be necessary before the closest relatives of rainforests. this species can be inferred. Snow, New species of Gossia & RJhodomyrtus 331 Notes: The label indicates that the bark is Conservation status: Given its occurrence in “very smooth, thin”, suggesting this species, only one known locality and following IUCN as with Gossia scottiana, might be related to (2001) guidelines the appropriate designation the “python” group of species in this genus is “Data Deficient” unless additional (Snow et al. 2003). populations are found. The following key separates species of Gossia presently known Etymology: The specific epithet refers to the long petioles, which with an average length of from Malesia. about 8 mm are the longest within Gossia. A key to the Malesian species of Gossia 1 Flowers 5-merous (rarely 4-merous in G. floribunda)\ leaf apex acuminate to attenuate.2 Flowers 4-merous; leaf apex obtuse, acute, or acuminate.3 2 Leaf blades mostly < 55 mm long; hypanthium sericeous; ovary apex villous.G. eugenioides Leaf blades mostly > 75 mm long; hypanthium glabrous; ovary apex glabrous.G. scottiana 3 Branchlets 4-angled.4 Branchlets rounded to compressed.5 4 Leaves broadly elliptic, 12-28 mm long; hypanthium densely appressed- pubescent; stipular hairs (see Snow et al. 2003) prominent, much elongated apically.G. versteeghii Leaves narrowly elliptic to ovate, 15-75 mm long; hypanthium glabrous to sparsely sericeous; stipular hairs somewhat obscure, only somewhat elongate apically.G. floribunda 5 Short, spine-like bracts in inflorescence present.G. salomonensis Short, spine-like bracts in inflorescence absent.6 6 Leaves membranous, narrowly elliptic.G. randiana Leaves coriaceous, elliptic to ovate.7 7 Petioles 7-10 mm long; leaf apex acuminate.G. longipetiolata Petioles 2-4 mm long; leaf apex acute.G. aneityensis Rhodomyrtus kaweaensis N.Snow, species laterally compressed internodes, sericeous. nov. a R. pinnatinervi C.T.White foliis Petioles 9-11 mm long, deeply channeled on pagina abaxiali sericea et apice acuto usque upper surface, longitudinally striated when acuminato, et pedunculis tenuioribus differt. young, densely sericeous. Stipular hairs Typus: Papua New Guinea: Morobe Province: of two to several ferrugineous to dark red Lae Subdistrict, Mt. Kawea, 600 m, 7 July hairs up to 0.8 mm long. Leaves discolorous, 1973, D.B.Foreman LAE 52304 (holo: BISH; matt above and below. Leaf blades narrowly iso: CANB, BRI, K, US). elliptic, 55-100 x 17-27 mm, base cuneate to Slender trees to 4.5 metres, up to 3 cm attenuate, apex acute to acuminate, margin d.b.h. Outer bark medium brown, smooth to flat; upper surface pannose while developing flaky; inner bark rich brown; wood straw- but becoming glabrous, oil glands not visible, coloured. Younger branchlets with two midvein impressed throughout; lower surface shallow longitudinal channels on each side of moderately short-hairy throughout (use 332 Austrobaileya 7(2): 325-340 magnification), oil glands common but faint, 4.5 mm, hypanthium tube not extended above intramarginal vein lacking. Inflorescence ovary apex, densely sericeous-tomentose; terminal or ramiflorous, of solitary flowers; ovary apex hairy. Calyx lobes 5, fused below, anthopodia and metaxyphylls absent. distinct in bud, c. 2.5 mm, light green, ovate Peduncles 3-10 mm, densely short-sericeous. to oblate, apex obtuse; upper surface densely Bracteoles 2, ovate, 2.2-2.3 x 0.8-1.0 mm, sericeous, lower surface moderately to densely tightly appressed to base of hypanthium, sericeous-tomentose. Petals ovate to obovate, thickened and keeled abaxially, sericeous to 5-8 x 3-4.2 mm, white, glabrous above and densely tomentose. Hypanthium obconic, 3.5— below, oil glands common and relatively FLORA OF NEW GUINEA Botanical Collections of the Division of Botany, Department of Forests, Lae. LAE 52304 D.U. Foreman 7/1/73 Locality: Mt. Kama. Lae Subdistrict, Iterobe District, Altitude 600 a, Lat. 7 25 S Long. 147 10 F. Habitat: nidge forest Annot.: Small tree. Height 6.0 a. Bark brown, smooth, inner bark pale brown. Wood pale brown loaves ll. Fig. 5. Holotype specimen of Rhodomyrtus kaweaensis (D.B.Foreman LAE 52304 [BISH]). Snow, New species of Gossia & RJhodomyrtus 333 prominent. Stamens 130-150, multiseriate, of the species the IUCN (2001) guidelines excluded, yellow; filaments 3-4 mm, pink; require a designation of “Data Deficient”. anthers subglobose, basifixed, c. 0.5 mm; Rhodomyrtus mengenensis N. Snow, species connectives with a single apical gland and nov. a R. pinnatinervi C.T.White indumento 1-6 additional glands between anther sacs; sericeo, et ramulis compressis et in quoque staminal disk shortly villous, diamter c. latere bicanaliculato differt. Typus: Papua 2.5 mm. Style c. 5 mm, glabrous, capitate. New Guinea. East New Britain: Subdistrict Locules (in flower) 6, placenta one per locule, Pomio, near mapping site at edge of Mengen axile; ovules numerous. Fruit unknown. Figs. Massif, 1200 m, 5°04'S, 151°48'E, 10 June 5 & 6. 1973, P.F. Stevens & Y. Lelean LAE58784 Presently known only from the type (holo: BRI; iso: A, CANB, E, K). collection. Slender trees to 4.5 metres tall, c. 3 cm dbh. Distribution and habitat: At the present time Outer bark medium brown, flaky; inner Rhodomyrtus kaweaensis is known only from bark darker brown; wood straw-coloured. forests on ridges at c. 600 metres altitude on Branchlets laterally compressed, those of the Mt. Kawea in Morobe Province west of the current year’s growth with two longitudinal Huon Gulf, about 80 air km south-southeast grooves on each side of the stem, moderately of Lae (Map 1). to densely sericeous. Petioles 10-16 mm long, deeply channeled on adaxial surface, Phenology: Flowering in January, presumably densely short-sericeous. Leaves discolorous, fruiting in late January through much of matt above and below. Leaf blades narrowly February or longer. elliptic, 75-100 x 22-30 mm, base cuneate to attenuate, apex acuminate, margin flat; Diagnostic attributes: Internodes of adaxial surface sericeous-lanate adaxially flowering branchlets 2-7 mm long; leaves when young, becoming glabrous (remaining brochidodromous, narrowly elliptic; sericeous around midvein), oil glands hypanthium irregularly creased longitudinally, not visible, midvein deeply impressed; densely sericeous-tomentose; petals sparsely abaxial surface sparsely to moderately hairy abaxially, densely sericeous adaxially; short-sericeous, especially along midvein stigma peltate. and veins; oil glands sparse to moderate Affinities: Rhodomyrtus pinnatinervis (best seen with magnification), secondary C.T.White is relatively common in New veins distinct, intramarginal vein lacking. Guinea and differs from R. kaweaensis by its Inflorescence terminal, axillary, or on naked narrower leaves, acuminate (versus typically branches, flowers solitary. Anthopodium and acute) leaf apex, less hairy abaxial leaf surface, metaxyphylls lacking. Peduncles solitary, 9- completely glabrous petals, and glabrous 11 mm, densely sericeous, typically reflexed styles lacking glands. On the basis of the away from stem (in fruit). Bracteoles 2, ovate, shape and venation of leaves R. mengenensis relatively thick and somewhat conduplicate also resembles R. kaweaensis, but the latter at base, c. 2 mm x 1 mm, rigid and tightly is easily diagnosed by its shorter (2-7 mm) appressed to base of hypanthium, sericeous- tomentose, persistent in fruit. Calyx lobes 5, internodes at the tips of branches. fused below, broadly rounded, apex obtuse, Notes: According to the label the leaves are 1.5-2 mm long, ascending in fruit; adaxial light green, but in dried material they are dark surface somewhat hairy; abaxial surface brown (above) to light brown (below). The densely short-tomentose. Petals 3-4 mm flowers are said to lack a scent. long; glabrous above and below, oil glands common and relatively large. Stamens Etymology: The specific epithet is in reference multiseriate; filaments c. 3 mm long; anthers to the type locality of Mt. Kawea. subcylindrical, c. 0.6 mm long; staminal disk Conservation status: Since analyses have not hairy. Styles glabrous; ovary apex hairy. been carried out to better document the range Immature fruit a berry, globose, 5-6 x 334 Austrobaileya 7(2): 325-340 Fig. 6. Close up of flowers of holotype specimen of Rhodomyrtus kaweaensis {D.B.Foreman LAE 52304 [BISH]). 5-6 mm, shortly sericeous-tomentose, dull Affinities: The combination of narrowly orange. Locules 6; placentation axile. Seeds elliptic leaves with brochidodromous venation numerous, ovate, testa hard. Embryo slightly most closely resembles R. kaweaensis, which curved to c-shaped. Figs. 7 & 8. is restricted to the main island of New Guinea. Presently known only from the type collection. Notes: The label from the type specimen reports the leaves as being slightly shiny Distribution and habitat: Rhodomyrtus above when fresh. The fruits are reportedly mengenensis is presently known only in dull orange in color, although it is unlikely Papua New Guinea from East New Britain that they are fully developed. on the edge of the Mengen Massif west of Wide Bay (Map 1); growing at 1200 metres Etymology: The specific epithet refers to the in Nothofagus-dominatQd mossy forests with type collection from the Megen Massif. Nastus Juss. Conservation status: IUCN (2001) guidelines Phenology: Probably flowering at least May require a designation of “Data Deficient” and June and fruiting June at least into July. General discussion Diagnostic attributes: Younger branchlets with two longitudinal grooves on each side of Rhodomyrtus sensu lato is demonstrably polyphyletic based on data from DNA the somewhat compressed internode; leaves sequences and morphological differences narrowly elliptic, venation brochidodromous; in leaf venation and aspects of the flower fruits reflexed from stem. (Csizmadi 2006). For example, cladograms