Rec. zool. Surv. India: llO(Part-2) : 49-55, 2010 NOTES ON NEW RECORDS OF MONOGONONT ROTIFERS (ROTIFERA : EUROTATORIA) FROM FLOODPLAIN LAKES OF ASSAM B.K.SHARMA Freshwater Biology Laboratory, Department of Zoology, North-Eastern Hill University, Permanent Campus, Shillong-793022, Meghalaya, e-mail: [email protected] AND SUMITA SHARMA Eastern Regional Station, Zoological Survey of India, Fruit Gardens, Risa Colony, Shillong-793003, Meghalaya, e-mail: [email protected] INTRODUCTION The different species are identified following the works Although systematic studies on the Indian Rotifera of Kutikova (1970), Koste (1978), Koste and Shiel (1989), began more than one century ago, the related Segers (1995) and Sharma (1998, 2007). The drawings investigations from North-Eastern India, one of the are made with a Leitz-Dialux phase contrast global biodiversity 'hot-spots', were initiated in the later stereoscopic microscope using a drawing tube half of 20th century. The status of faunal diversity of attachment and measurements are indicated in Rotifera of N.E. region is reviewed by Sharma and micrometers (/lm). Segers (2002) is followed for the Sharma (2005a). In addition, several new records of recent system of nomenclature of Rotifera and remarks interesting taxa from this region have been reported by on the distribution are made vide Segers (2007). The Sharma (2004, 2005, 2007). reference materials are deposited in the holdings of the senior author (BKS) at, Department of Zoology, North­ The present study, a part of comprehensive survey Eastern Hill University, Shillong. of the Rotifera biodiversity in N.E. India, deals with ten species of rare and interesting monogonont rotifers LIST OF THE EXAMINED SPECIES collected from the floodplain lakes (beels) of the Phylum ROTIFERA Brahmaputra river basin of Assam. The documented Class EUROTATORIA species include four new records from India, four new Subclass MONOGONONTA reports from Northeastern region and two new records from Assam. All the examined species are briefly Order PLOIMA diagnosed and illustrated and remarks are made their Family EUCHLANIDAE distribution. Tripieuchianis plicata (Levander, 1894)** MATERIALS AND METHODS Family LEPADELLIDAE The present observations are based on plankton Colurella colurus (Ehrenberg, 1830)* samples collected during January-December, 2007 from Lepadella bicornis Vasisht & Battish, 1971 *** various floodplain lakes (beels) of the Brahmaputra river L. eiongata Koste, 1992* basin of Assam by towing a nylobolt plankton net (No. L. Iatusinus (Hilgendorf, 1889)* 25) and preserved in 5% formalin. The samples are screened, the rotifer taxa are isolated and mounted L. rhomboiduia (Bryce, 1890)** individually in Polyvinyl alcohol-Iectophenol mixture. L. triptera alata (Myers, 1934)* 50 Rec. zooz. Surv. India Fmnily LEC~AE Distribution: N.E. India: New record. India: Lecane aspasia Myers, 1947** Chandigarh (U.T.). Elsewhere: Brazil. L. elegans Harring, 1914*** Lepadella elongata Koste, 1992 L. elongata Harring & Myers, 1926** (Figs. 8-9) Material examined: 4 examples, RlBKSIAssam/247- TAXONOMIC NOTES 250, Muijan beel, (Dibrugarh district), 26.08.2006, colI. Tripleuchlanis plicata (Levander, 1894) B.K. Sharma. (Figs. 1-3) Characters: Lorica oblong in outline, with maximum Material examined: 6 examples, RlBKSIAssam/211- width in its middle region; posterior end of lorica 216, Deepor beel, Dharapur (Kamrup district), 26.08.2006, narrower and slightly truncate. Anterior opening deep, colI. B.K. Sharma. nearly U-shaped dorsally and V-shaped ventrally. Foot­ Characters : Lorica rigid and ovoid, with double opening elongated, nearly parallel-sided; toes long and cuticular folds between dorsal and ventral plates. Foot pointed. robust, three-segmented and often projecting beyond Distribution : India : new record. Elsewhere lorica. Toes short, parallel-sided and with pointed tips. Neotropical, Oriental and Pacific regions. Distribution: N.E. India: New record India: West Lepadella latusinus (Hilgendorf, 1889) Bengal, Andhra Pradesh and Tamil Nadu. Elsewhere: (Figs. 10-12) Cosmopolitan. Material examined: 4 examples, RlBKSIAssam/252- Colurella colurus (Ehrenberg, 1830) 255, Maghuri beel, Guijan (Tinsukia district), 12.05.2008, (Figs. 4-5) colI. B.K. Sharma. Material examined: 3 examples, RlBKSIAssam/231- Characters : Lorica elongated-oval, broadest in 233, Padmakhua beel (Morigaon district), 20.03.2007, middle and then tapering slightly to each end; vaulted colI. B.K. Sharma. hemispherical in corss-section. Occipital margin cowl­ Characters: Lorica oblong in outline, with maximum like and ventrally protruding; head aperture small, with width slightly before its middle and rounded posterior slightly convex dorsal margin and a deep U-shaped end; anterior lorica margin rounded. Foot three­ ventral sinus. Foot-operning wide and with outwardly segmented; toes long, slender and pointed. curved corners; last foot-segment < Y2 toe length. Toes Distribution : India : new record. Elsewhere elongated, pointed and ventrally directed. Cosmopolitan. Distribution : India : new record. Elsewhere Cosmopolitan. Lepadella bicornis Vasisht & Battish, 1971 (Figs. 6-7) Lepadella rhomboidula (Bryce, 1890) Material examined: 3 examples, RlBKSIAssam/241- (Figs. 13-15) 243, Amuri beel, (Morigaon district), 18.09.2007, colI. Material examined: 3 examples, RlBKSIAssam/259- B.K. Sharma. 261, Deepor beel, Dharapur (Kamrup district), 26.08.2006, Characters : Lorica broadly ovate, moderately colI. B.K. Sharma. compressed dorso-ventrally; with prominent acutely Characters : Lorica rhomboidal in outline, with pointed broad-based corners laterally. Anterior dorsal moderately high dorsal keel and maximum width in its margin concave and anterior ventral sinus v-shaped. middle region. Dorsal sinus lacking. Ventral sinus Foot-groove shallow. Foot 4-segmented, distal foot­ shallow and semicircular. Foot-groove inverted U­ segment longest; toes equal and pointed. shaped; toes short and pointed. * New record from India * * New Record from N .E. India *** New record from Assam SHARMA & SHARMA: Notes on new records oj Monogonont Rotifers (Rotifera : Eurotatoria} ......... oJ Assam 51 Tripleuchlanis plicata (Levander, 1894) : Fig. 1. dorsal view; Fig. 2. lateral view, Fig. 3. trophi; Colurella colurus (Ehrenberg, 1830) : Fig. 4. lateral view, Fig. 5. ventral view : Lepadella bicornis Vasisht & Battish, 1971; Fig. 6. dorsal view, Fig. 7. ventral view; Lepadella elongata Koste, 1992; Fig. 8. dorsal view, Fig. 9. ventral view; Lepadella latusinus (Hilgendorf, 1889); Fig. 10. ventral view, Fig. 11. lateral view, Fig. 12. cross-section. Distribution: N.E. India: New record. India: West Characters : Lorica small, rhombic in outline, Bengal. Elsewhere : African, Australian, Oriental and broadest in its middle region. Dorsal surface of lorica Palaearctic regions. vaulted, with high median keel and slightly produced Lepadella triptera aIata (Myers, 1934) posterior end. Head aperture small, with a slight median (Figs. 16-18) notch dorsally and shallow U-shaped sinus ventrally. Material examined: 4 examples, RlBKSIAssam/265- Foot-opening small and oval. Toes short and pointed. 268, Deepor beel, Dharapur (Kamrup district), 26.08.2006, Distribution: N.E. India: New record. India: new colI. B.K. Sharma. record. Elsewhere: Cosmopolitan. 52 Rec. zooz. Surv. India 13 14 50 J.lID 50 J.lID 21 22 50 J.lID Lepadella rhomboidula (Bryce, 1890); Fig. 13. dorsal view; Fig. 14. ventral view; Fig. 16. cross-section; Lepadella. triptera alata (Myers, 1934); Fig. 16. dorsal view; Fig. 17. ventral view, Fig. 18. cross-section; Lecane aspasia Myers, 1947; Fig. 19. ventral view; Lecane elegans Harring, 1914; Fig. 20. ventral view; Lecane elongata Harring & Myers, 1926; Fig. 21. dorsal view, Fig. 22. ventral view. Lecane aspasia Myers, 1947 ventral occipital margin with small antero-Iateral spines. (Figs. 19) Dorsal plate narrow anteriorly, nearly as wide as ventral Material examined: 3 examples, RlBKS/Assam/280- plate and ornamented. Ventral plate longer than wide, 282, Itakhuli beel, (Dibrugarh district), 12.05.2008, colI. with incomplete transverse fold and few longitudinal B.K. Sharma. folds. Posterior segment rounded. Foot pseudo segment Characters: Lorica elongated, lateral sulci shallow; wider than long and slightly projecting. Toes parallel­ anterior margins nearly straight and coincident and sided, with sharp completely separated claws. SHARMA & SHARMA: Notes on new records oj Monogonont Rotifers (Rotifera : Eurotatoria} ......... oJ Assam 53 Distribution: N.E. India: New record. India: Delhi. state of Assam. The recorded taxa are rare elements in Elsewhere: Cosmopolitan. the examined material and these include six Cosmopolitan, one Holarctic, one Palaeotropical and Lecane elegans Harring, 1914 one Pantropical elements while one species is so far (Fig. 20) known from the Neotropical, Oriental and Palaearctic Material examined: 2 examples, RlBKS/Assam/289- regions. 290, Memdubi beel, Guijan (Tinsukia district), 15.05.2008, Among the members of the Lepadellidae, Lepadella colI. B.K. Sharma. elongata merits distributional interest with earlier Characters: Lorica smooth, elongated and slender, reports from Brazil, Ecuador and Nigeria and, its only anterior occipital margins nearly straight and coincident. report from the Oriental region dealt with occurrence in Lateral sluci indistinct. Ventral plate with few Thailand (Sanoamuang and Savatenalinton, 1999). The longitudinal folds. Foot plate large. Second foot-segment present second