Data from: Albian infaunal Pholadomyida (Cretaceous Bivalvia), Comanchean Carbonate Shelf, Texas

Species of the Megaorder Poromyata, although common and relatively diverse in Albian-lower Cenomanian Comanchean strata in Texas and northern Mexico, have been neglected as biostratigraphic markers and paleoecological indicators. Since 1852 more than a dozen species have been identified as Homomya Agassiz, Order Pholadomyida, Superfamily Pholadomyoidea, or Pleuromya Agassiz, Order Pholadida, Superfamily Pleuromyoidea. Because valve morphologies of both genera are similar in many ways, casts of both genera are difficult to separate. Statistical analysis of key morphological properties objectively defines species concepts and assesses synonymies. Eight species are retained in Homomya, four are synonymized with these; two species are provisionally retained in “Homomya” although they differ significantly. One species is re-assigned to Liopistha (Sergipemya) alta (Roemer). Pleuromya henselli (Hill) is re-assigned to Panopea.
Homomyid species range from upper Aptian to lower Cenomanian of the Comanchean Series in Texas and Mexico. Their ranges vary in duration from one million years up to eight million years. Two sets of species are distinct morphotypes: a smaller-sized set of H. knowltoni, H. tarrantensis, H. tlahualiloensis, H. kellumi, and a larger-sized set of H. cymbiformis, H. austinensis, H. vulgaris, H. budaensis, and H. auroraensis. Two end-member morphotypes are represented by the ‘streamlined’ Homomya knowltoni, which is an elongate, slightly inflated form with a relatively high umbo, and the cylindrical Homomya budaensis; which is a very elongate, tubular, inflated form with a very low umbo. These infaunal suspension feeders occupied calcareous mud and carbonate shelf substrates.

尽管多孔蛤大目（Poromyata）的物种在德克萨斯州与墨西哥北部的阿尔必阶（Albian）-森诺曼阶（Cenomanian）下部科曼奇统（Comanchean）地层中分布广泛且多样性相对较高，但它们作为生物地层标志（biostratigraphic markers）与古生态指示物（paleoecological indicators）的研究价值长期被忽视。自1852年以来，已有十余个物种被归入霍莫蛤属（Homomya Agassiz，海笋目（Pholadomyida），海笋超科（Pholadomyoidea）），或肋蛤属（Pleuromya Agassiz，海螂目（Pholadida），肋蛤超科（Pleuromyoidea））。由于两属的贝壳瓣形态（valve morphologies）在诸多方面高度相似，其铸型标本（casts）难以区分。针对关键形态特征的统计分析可客观界定物种概念（species concepts）并评估同物异名（synonymies）情况：霍莫蛤属中共保留8个有效物种，另有4个被厘定为上述物种的同物异名；另有2个物种虽存在显著形态差异，但仍暂时置于“霍莫蛤属”（Homomya）范畴内。1个物种被重新归属于里奥蛤属（塞氏蛤亚属）高大里奥蛤（Liopistha (Sergipemya) alta (Roemer)）；肋蛤属的亨氏肋蛤（Pleuromya henselli (Hill)）则被重新划归为海神蛤属（Panopea）物种。科曼奇统德克萨斯与墨西哥地区的霍莫蛤类物种的产出层位跨度从阿普第阶（Aptian）上部延伸至森诺曼阶下部，其地层延续时长从100万年至800万年不等。该类群可分为两类显著的形态型：一类为小型类群，包含诺氏霍莫蛤（Homomya knowltoni）、塔兰特霍莫蛤（H. tarrantensis）、特拉瓦利略霍莫蛤（H. tlahualiloensis）、凯卢姆霍莫蛤（H. kellumi）；另一类为大型类群，包含舟形霍莫蛤（H. cymbiformis）、奥斯汀霍莫蛤（H. austinensis）、普通霍莫蛤（H. vulgaris）、布达霍莫蛤（H. budaensis）与极光霍莫蛤（H. auroraensis）。两种端元形态型分别为“流线型”的诺氏霍莫蛤（Homomya knowltoni）：该物种呈细长、轻度膨凸形态，具相对高耸的壳顶；以及圆柱形的布达霍莫蛤（Homomya budaensis）：该物种呈极细长的管状膨凸形态，壳顶极低。这类底内悬浮食性生物（infaunal suspension feeders）栖息于钙质泥（calcareous mud）与碳酸盐陆架基质（carbonate shelf substrates）环境中。