Shipway J Reuben, Altamia Marvin A, Rosenberg Gary, Concepcion Gisela P, Haygood Margo G, Distel Daniel L
Ocean Genome Legacy Center, Department of Marine and Environmental Science, Northeastern University, Nahant, MA, United States of America.
Academy of Natural Sciences, Drexel University, Philadelphia, PA, United States of America.
PeerJ. 2019 Feb 7;7:e6256. doi: 10.7717/peerj.6256. eCollection 2019.
Here we describe an anatomically divergent wood-boring bivalve belonging to the family Teredinidae. Specimens were collected off the coast of Mabini, Batangas, Philippines, in February 2018, from sunken driftwood at a depth of less than 2 m. A combination of characteristics differentiates these specimens from members of previously named teredinid genera and species. Most notable among these include: an enlarged cephalic hood which extends across the posterior slope of the shell valves and integrates into the posterior adductor muscle; a unique structure, which we term the 'cephalic collar', formed by protruding folds of the mantle immediately ventral to the foot and extending past the posterior margin of the valves; a large globular stomach located entirely posterior to the posterior adductor muscle and extending substantially beyond the posterior gape of the valves; an elongate crystalline style and style sac extending from the base of the foot, past the posterior adductor muscle, to the posteriorly located stomach; calcareous pallets distinct from those of described genera; a prominently flared mantle collar which extends midway along the stalk of the pallets; and, separated siphons that bear a pigmented pinstripe pattern with highly elaborate compound papillae on the incurrent siphon aperture. We used Micro-Computed Tomography (Micro-CT) to build a virtual 3D anatomical model of this organism, confirming the spatial arrangement of the structures described above. Phylogenetic analysis of the small (18S) and large (28S) nuclear rRNA gene sequences, place this bivalve within the Teredindae on a branch well differentiated from previously named genera and species. We propose the new genus and species to accommodate these organisms, raising the total number of genera in this economically and environmentally important family to 17. This study demonstrates the efficacy of Micro-CT for anatomical description of a systematically challenging group of bivalves whose highly derived body plans are differentiated predominantly by soft tissue adaptations rather than features of calcareous hard-parts.
在此，我们描述了一种属于船蛆科的、在解剖结构上具有差异的钻木双壳贝类。标本于2018年2月在菲律宾八打雁省马比尼海岸外采集，取自深度小于2米的沉没浮木。一系列特征将这些标本与先前命名的船蛆属的成员区分开来。其中最显著的特征包括：一个扩大的头部罩，其延伸穿过壳瓣的后坡并融入后闭壳肌；一个独特的结构，我们称之为“头部领圈”，由外套膜紧靠足部腹侧的突出褶皱形成，并延伸至壳瓣后缘之外；一个大的球形胃，完全位于后闭壳肌后方，并大幅延伸至壳瓣后开口之外；一条细长的晶杆和晶杆囊，从足部基部延伸，经过后闭壳肌，到达位于后方的胃；与已描述属不同的钙质盘；一个显著向外扩张的外套膜领圈，沿盘柄延伸至中途；以及分开的虹吸管，在入流虹吸管孔上带有色素沉着的细条纹图案和高度复杂的复合乳突。我们使用微计算机断层扫描（Micro-CT）构建了这种生物的虚拟三维解剖模型，证实了上述结构的空间排列。对小（18S）和大（28S）核糖体RNA基因序列进行系统发育分析，将这种双壳贝类置于船蛆科内一个与先前命名的属和种明显不同的分支上。我们提出新的属和种来容纳这些生物，使这个在经济和环境方面都很重要的科中的属总数增加到17个。这项研究证明了Micro-CT在解剖描述一类系统分类具有挑战性的双壳贝类方面的有效性，这类双壳贝类高度特化的身体结构主要通过软组织适应而非钙质硬体部分的特征来区分。
