MORPHOLOGY AND PALAEOECOLOGY OF NEW, NON-MARINE MICROCONCHID TUBEWORM FROM LOWER CARBONIFEROUS (UPPER MISSISSIPPIAN) OF WEST VIRGINIA, USA

A new species of a non-marine microconchid (Tentaculita) tubeworm, Microconchus hintonensis, from the Lower Carboniferous (Upper Mississippian, Chesterian) of West Virginia, USA, is described. Non-marine microconchids occur abundantly in the deposits of the Bluefield, lower Hinton, Prince ton and Bluestone Formations of the Mauch Chunk Group, where they are either associated with land plant re mains and bivalve shells, or are preserved loose in the host sediment. The specimens attached to plant re mains and bivalve shells, are poorly preserved, but those occur ring loose in the de posits are well-preserved in three dimensions. The interpretation presented here, is that the loose specimens of Microconchus hintonensis sp. nov. also originally en crusted plants (land plants, algae) and bivalve shells, but be came detached after substrate degradation and dissolution. The association of land plant re mains, charophyte gyrogonites, bivalves, ostracodes, conchostracans, and fish teeth and scales, and the concomitant lack of strictly marine fossils indicate that the microconchid-bearing de posits of the lower Hinton, Prince ton and Bluestone Formations were de posited in fresh-water environments. Microconchus hintonensis sp.nov. is regarded as a highly fecund, opportunistic species that in large numbers colonized every avail able substrate in its habitat. Its abundance in the deposits investigated indicates that the species was well-adapted to the environments it occupied, even during episodes of higher sedimentation rates and/or competition with other soft-bodied encrusters. During such episodes, microconchids were able to grow vertically by uncoiling and elevating their tubes, in order to escape potential burial and/or overgrowth by other encrusters.