New Desmids From Thailand

เดสมิดส์ชนิดใหม่ที่พบในประเทศไทย ประเทศไทยตั้งอยู่ในภูมิภาคเขตร้อนชื้นซึ่งมีพืชและสัตว์ต่าง ๆ อาศัยอยู่เป็นจำานวนมาก จึง เป็นแหล่งที่มีความหลากหลายทางชีวภาพอย่างมาก ทำาให้มีการศึกษาพบพืชหรือสัตว์พันธุ์ใหม่ของ โลกบ่อยครั้ง จากการสำารวจถึงความหลากหลายทางชีวภาพของ สาหร่ายสีเขียว กลุ่มเดสมิดส์ ในหลายๆ ภูมิภาคของประเทศไทย พบความหลากหลายค่อนข้างสูง พบทั้งหมด 30 สกุล 460 ชนิด โดยมี 2 สกุล 85 ชนิด เป็นชนิดรายงานเป็นครั้งแรกในประเทศไทย (new record) ในการศึกษาครั้งนี้พบเด สมิดส์ชนิดใหม่ (new species) 1 ชนิด 2 สายพันธ์ (ตีพิมพ์แล้ว) ยังมีที่คาดว่าเป็นชนิดใหม่ อีก 5 ชนิด ซึ่งกำาลังตรวจสอบ และจัดทำารายละเอียดเพื่อการตีพิมพ์

1 Micrasterias tetraptera W. et G.S. West var. siamensis NGEARNPAT et PEERAPORNPISAL var. nov. พบในพรุจูด จังหวัด ตรัง

Descriptio: A varietate nominata differt lobis lateralibusincisuris ordine secundo tantum (in semicellulae parteinferiore) vel tertio (in semicellulae parte superiore);spinis intramarginalibus absentibus. Cellularum longitudo190–195 μm, latitudo 155–163 μm. Typus: figuranostra 6. Differs from the nominate variety in that the lateral lobes in the lower part of the semicell are only differentiated to the second order (instead of the thirdorder), those in the upper part of the semicell only to the third order (instead of the fourth order). In addition to that, any intramarginal spines are lacking. Holotypus: Preserved material has been deposited inthe Culture Collection of Algae of Applied Algal ReserchedLaboratory (AARL), Faculty of Science ,ChiangMai University, Thailand as specimen No. PREAARL-G001 Type locality: M. tetraptera var. siamensis was collectedin Jud peat swamp, a mesotrophic, slightly acidic(pH 6.1) fen, where it occurred in a shallow drainagecanalwith floating mats of bladderworts and filamentousalgae. Collector: Neti Ngearnpat. Date of collecting: January, 6, 2006 Ngearnpat N. , Coesel P. F.M. and Peerapornpisal Y. 2008. Diversity of desmids in three Thai peat swamps. Biologia 63/6: 897—902.

2. Xanthidium lenticulare COESEL, NGEARNPAT et PERAPORNPISAL sp. nov. 3. Sphaerozosma aubertianum W. West var. indicum (W.B. TURNER) COESEL et NGEARNPAT comb. nov. พบใน บึงหนองเขียว จังหวัด เชียงราย Coesel P. F.M. , Ngearnpat N. and Peerapornpisal Y. 2009. Some new or otherwise interesting desmid taxa from Thailand. Algological studies, 129: XX-XX ( impress)

Xanthidium lenticulare COESEL et NGEARNPAT sp. nov. Diagnosis: Cellulae paulum latiores quam longiores profunde constrictae. Sinus linearis extremitate dilatata. Semicellulae conspectu frontali trapeziformes angulis late rotundatis. Margines apicales lateralesque tuberculorum confertorum aplanatorum serie numero variabili praeter margines laterales spina breviore longioreve valida. Paries cellularis in semicellulae parte mediali amplificatione circulariformi. Semicellulae conspectu laterali subcirculari-octogonali tuberculorum spinosorum seriebus

medialibus longitudinalibus. Semicellulae ambabus lateribus parietis cellularis tubere pellucido semicirculari chloroplasti in semicellulae interiore invaginatione crateriformi congruentiter. Paries cellularis porosus tuberibus semicircularibus exceptis. Cellulae praeter spinos 77-86 µm longae, cum spinis 106-117 µm longae, praeter spinos 63-76 µm latae, cum spinis 92-102 µm latae, cellulae tuberibus exclusis 42-45 µm crassae, tuberibus inclusis 60-68 µm crassae, isthmi latitudino 21-25 µm. Typus: Figura nostra 6.

Cells slightly longer than broad, deeply constricted. Sinus linear with a dilated extremity. Semicells in frontal view trapeziform with broadly rounded angles. Apical and lateral margins with a series of closely set, flattened tubercles, a variable number of which along the lateral margins are provided with a shorter or longer, stout spine. Cell wall in the central part of the semicell with a ring-shaped thickening. Semicells in lateral view subcircular-octogonal with two median, longitudinal rows of spiny tubercles. Either side of the semicell with a transparent, semicircular bulge of the cell wall corresponding with a crater-shaped invagination of the chloroplast in the interior of the semicell. Cell wall porose, except for the semicircular bulges. Cell length exclusive of spines 77-86 µm, inclusive of spines 106-117 µm, cell breadth exclusive of spines 63-76 µm, inclusive of spines 92-102 µm, cell thickness exclusive of bulges 42-45 µm, inclusive of bulges 60-68 µm., breadth of isthmus 21-25 µm. Type: our Fig. 6. Type locality: Nong Keaw lake, Coesel and Ngearnpat, 3 February 2008, plankton collection no. 2008.01 in the Amsterdam University herbarium, plankton collection no. PRE AARL-G002 in CMU Algal Collection, Chiang Mai University. Xanthidium lenticulare is a remarkable desmid, not to be confused with any other species. The series of closely set tubercles along the lateral cell margins resemble those in Xanthidium superbum Elfving and Xanthidium sansibarense (Hieron.) Schmidle but differ in the number of associated spines. Whereas in X. superbum all lateral tubercles bear a stout spine and in X. sansibarense only those at the apical and lateral angles, in X. lenticulare number and length of the spines are variable (Figs 6, 7). The most striking characteristic of X. lenticulare, however, is the ring-shaped cell wall thickening in the centre of the semicell connected with a conspicuous, transparent semicircular bulge and associated, towards the inside of the semicell, with a crater-like invagination of the chloroplast (Figs 6 and 8). By this a lense-like function is suggested. It is pretty hard to imagine in what way X. lenticulare could benefit by this specific cell structure but if it would function as a specialized lense indeed, it would be a unique feature among the unicellular, phototrophic protists. X. lenticulare was rather regularly encountered in our Nong Keaw sample and, except for number and lenght of the spines, appeared to be highly uniform in its appearance. Sphaerozosma aubertianum W. West var. indicum (W.B. TURNER) COESEL et NGEARNPAT comb. nov. Basionym: Sphaerozosma vertebratum Ralfs var. indicum W.B. TURNER, Kongl. Svenska Vetensk. Acad. Handl. 25 (5): 140, fig. 18 (1892). Our Fig. 4 well agrees with Sphaerozosma vertebratum var. indicum as described by TURNER (1892) from India. The difference between Sphaerozosma vertebratum RALFS and Sphaerozosma aubertianum W. WEST is mainly in the shape of the sinus: linear and only narrowly open in Sph. vertebratum, widely opening to the exterior in Sph.

aubertianum (WEST et al. 1923). Therefore, TURNER’s (1892) Sph. vertebratum var. indicum is better to be accounted Sph. aubertianum. Sph. aubertianum var. indicum differs from the nominate variety of Sph. aubertianum by a cell sinus that is open from its very apex giving rise to a distinct, not seldom slightly lengthened isthmus. In addition to that, the semicell lobes often are somewhat curved downwards.Sph. aubertianum var. indicum occurred as a rather common taxon in Nong Keaw lake, Chiang Rai. As it was also found in other Thai lakes it is presumably widely distributed in the Indo-Malaysian region.

เอกสารอ้างอิง Peerapornpisal Y., Suphan S, Ngearnpat N. and Pekkoh J. 2008. Distribution of chlorophytic phytoplankton in Northern Thailand. Biologia 63/6: 848—854. Ngearnpat N. , Coesel P. F.M. and Peerapornpisal Y. 2008. Diversity of desmids in three Thai peat swamps. Biologia 63/6: 897—902. Ngearnpat N. and Peerapornpisal Y. 2007. Application of desmid diversity in assessing the waterquality of 12 freshwater resources in Thailand. J Appl Phycol. 19:667– 674. Coesel P. F.M. , Ngearnpat N. and Peerapornpisal Y. 2009. Some new or otherwise interesting desmid taxa from Thailand. Algological studies, 129: XX-XX ( inpress)