New Records of Seagrass Flora in Air Bangis West Sumatera

Seagrasses in the Air Bangis Archipelago, west coast of Sumatra were found growing in sandy muddy substrates of the shallow coastal waters at depth of 0.3-2.5 m, dominated by degraded coral reefs around the off-shore islands. Two species; Enhalus acoroides (L.f) Royle and Thalassia hemprichii (Ehrenb) Aschers were observed at Pulau Unggas, Pulau Pasir Panjang and Teluk Tapang. Halodule uninervis (Forssk) Aschers was observed in two locations; Pasir Panjang and Teluk Tapang. The occurrence of this species is unknown previously and therefore it is a new flora record for Sumatra. With this new record, Sumatra has six species of seagrasses, contributing to half of total number of seagrasses occurring in Indonesia. According to leaf width measurements, two morphological variants (narrow and wide leaved) can be distinguished for Halodule uninervis. In addition, descriptions of the species and their habitat characteristic are provided.


INTRODUCTION
Past records based on various collections from 1919 to 1936 indicated that five seagrass species were found in east coast of Sumatra (den Hartog, 1957;1970).

MATERIALS AND METHODS
Field surveys were undertaken in the waters of Air Bangis Archipelago intertidally.Specimens were collected with hand and a shovel, stored in plastic bags and preserved in 4% formalin and processed into herbarium following the method of Menez et al., (1983).
After identification based on den Hartog (1970)

RESULTS AND DISCUSSION
Historical and Present Records.Five seagrass species have been reported and almost all were records from the Riau Archipelago, Eastern Sumatra (den Hartog, 1970).Specimens of seagrasses were placed at various herbaria around the world at: British Museum (Natural History), London, England (BM); Herbarium Bogoriense, Bogor, Indonesia (BO); Herbarium of the Royal Botanic Gardens, Kew, Richmond, England (K); Rjiksherbarium, Leyden, the Netherlands (L); Herbarium of the National University of Singapore (before Herbarium of the Botanic Gardens, SING) and Botanical Museum and Herbarium, Utrecht, the Netherlands (U).

Family CYMODOCEACEAE .
Cymodocea rotundata Ehrenb.& ex Aschers.Riau Archipelago: Tanjung Pinang, undated, Teysmann (BO).At present, there have been reports on the occurrence of seagrasses; Enhalus acoroides, Thalassia and Halophila species inhabiting the intertidal and muddy areas of Bintan Island, Riau Archipelago(Soeharmoko, 1985;Kusdiarti et al., 1989;Erlambang & Siregar, 1995).Additional records from Air Bangis Archipelago, Western Sumatra obtained from our study are as follows; Stratiotes acoroides L.f.Vallisneria sphaerocarpa BlancoCommon name: Tropical eelgrass Distribution and Ecology.Pulau Panjang-Moderate population growing together with Halodule uninervis (narrow leaved variant) and Thalassia hemprichii in the lower inter-tidal zone (depth 0.8-1.5m) on sand covered coral rubbles and dens pure population in the upper sub-tidal zone (depth 1.5-2.0m) on sandymuddy substrates.Male and female flowering specimens were collected in this area.Pulau Unggas-A sparse and isolated patches were found growing on muddy sand and occasional plants were observed growing on sand covered dead corals.No flowering specimen was found.Teluk Tapang-Moderate population covering large areas growing together with Thalassia hemprichii on sandy substrate (depth 1.0-1.2m) directly in front of the mangrove.Further away from the mangrove, Enhalus population formed patches or only as occasional plant with Thalassia hemprichii and Halodule uninervis (wide leaved variant).In shallow water (depth 0.3-1.0m), Enhalus and the associates grew on sand covered coral rubbles and dead coral.No flowering specimen was found.Pulau Taming-Sparse population and occasional plants was observed growing with Thalassia hemprichii on sand covered dead corals.No flowering specimen was found.Description.Plants large, dioeciously; rhizomes 13-25 mm thick with long, black fibrous bristles; usually embedded in the substratum numerous anabranches root varies 125 to 330 mm in length and without root hairs.Shoot produced at the nodes with 1-5 leaves.Leaf blades, dark green, flat and linear, 230-530 mm long and 13-17 mm wide with many parallel veins; midrib conspicuous; leaf tip rounded or obtuse; leaf margins entire.Male inflorescence on a short peduncle reaching 30 mm long; spathal leaves ovate-lanceolate, obtuse keeled measured 45 mm long and 16 mm wide.Rough