Trinema lineare Penard, 1840

Sharma, B. K. & Sharma, Sumita, 2011, Testate amoebae (Protozoa: Rhizopoda) of Deepor Beel (a Ramsar site), Assam, northeastern India, Journal of Threatened Taxa 3 (7), pp. 1947-1950 : 1949-1950

21. Trinema lineare Penard, 1840

Characters: Test small, hyaline, elongate, composed of small circular platelets. Oral aperture circular, oblique, invaginated and bordered by toothed platelets.

Distribution: India - Assam, Arunachal Pradesh, Meghalaya, Manipur, Mizoram, Nagaland, Tripura, Himachal Pradesh, Sikkim and West Bengal.

Discussion

Our collections show 14 species of Lobosea and seven species of Filosea, the L/F ratio of 2 is close to the 3.0 reported by Sharma & Sharma (2008) from various floodplain lakes of Assam but exceeds the range of 0.5–1.4 reported for moss-dwelling rhizopods ( Chattopadhyay & Das 2003). Euglyphidae > Centropyxidae = Difflugidae , three speciose families, comprise the dominant fraction (76.2%) of the reported species. Cyphoderiidae and Nebelidae , the least species-rich families, include one species each. Further, Difflugia > Centropyxis are relatively diverse genera (42.9%) while Arcella = Euglypha also form a notable fraction (28.6 %) in this study.

The total Rhizopoda richness of Deepor Beel is higher than the 16, 12, 7 and 19 species examined from the freshwater biotopes of Meghalaya ( Das et al. 1995), Tripura ( Das et al. 2000), Sikkim ( Das et al. 2003) and Manipur ( Das et al. 2004) respectively. Further, the richness is higher than the reports of 16 species from Loktak Lake - a Ramsar site (refer Das et al. 2004); 10 species from Melghat Wildlife Sanctuary (Bindu 2010), Maharashtra; 13 species from Pench National Park, Maharashtra and also 7–16 species listed from 15 floodplain lakes of the Brahmaputra river basin of Assam ( Sharma & Sharma 2008). However, we caution against over-emphasizing the importance of these comparisons without considering sampling intensity and the nature of different ecosystems. In analyzing the comparative species-richness of our and other communities, it also needs to be emphasized that the number of species recorded to date are yet provisional and these may well be revised in light of future research.

Whilst Centropyxis orbicularis and Cyphoderia ampulla currently exhibit restricted occurrence in India with reports from Sikkim and Uttarakhand respectively, their distribution ranges were extended recently to Assam ( Sharma &Sharma2008). The mossdwelling Cyphoderia ampulla was recently observed in freshwater from Assam ( Sharma & Sharma 2008) and Maharashtra (Bindu 2010); the present report re-affirming its occurrence in freshwater environs merits ecological interest. Our report also endorses an identical report ( Sharma & Sharma 2008) of Cyclopyxis eurystoma which was known from soil and mosses in India ( Chattopadhyay & Das 2003). Arcella hemispherica , Centropyxis cassis , Difflugia corona , D. tuberculata , D. urceolata , Cyclopyxis eurystoma , and Euglypha laevis comprise examples of local or regional distributional interest. Further, these species exhibit rare occurrence in our collections. On the other hand, Arcella discoides , A vulgaris , Centropyxis aculeata , C. ecornis , Difflugia acuminata , D. oblonga , Euglypha acanthophora and E. tuberculata exhibit relatively frequent occurrence.

The present report raises the total number of Rhizopoda so far known from different ecosystems of Assam to 49 species, affirming the biodiversity value of this Ramsar site. The observed association of Rhizopoda with different aquatic macrophytes merits future interest, and studies of this and other ecological aspects have been initiated by the authors.