A Generic Revision of the Stylasteridae (Coelenterata: Hydrozoa) Part 3 Keys to the Genera
A Generic Revision of the Stylasteridae (Coelenterata: Hydrozoa) Part 3 Keys to the Genera
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Stylasteridae（腔肠动物门：水螅纲）的一般修订第 3 部分属要点
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发表时间：
1984
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影响因子：
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通讯作者：
S. Cairns
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作者：
S. Cairns
本文给出了针菊科23个属、2个亚属和5个种群的分类表。这些键强调易于识别的外部骨骼特征，其中大部分可以在解剖显微镜下看到，如：指趾孔和胃孔的配合、胃和指趾柱的有无、环系取向、指趾孔棘的形状、壶体的位置、胃孔管的形状、指趾孔管的长度和囊鞘结构。在其辨别能力和系统发育价值的背景下，简要地讨论了这些特征。介绍了两个新的术语来描述趾尖孔管：轴向和外周。列出了每个属的有效种数及其地理和水深范围。有224种柱头虫被认为是有效的，其中包括24种专门的化石种。花柱星形分布在世界各地，但在分布上是孤立的，范围从0-2,789米。这是最初设想的两部分系列的第三部分，第一部分是对柱头虫属的描述（Cairns, 1983b），第二部分是对这些属的系统发育分析（Cairns, 1984）。然而，在研究中断了两年之后，我发现需要识别大量的柱头类，我发现构建并在此发布该科属的二分类和表格键是很有用的。这种表格键可以从第2部分公布的编码数据矩阵中提取（Cairns, 1984: 52-53，附录2）；但是，这些数据的呈现方式不便于解释或作为关键随时使用。这些键的目的是提供一个有效和准确的方法来识别和比较使用最容易识别的字符stylasterid属。因此，所使用的字符不一定是最重要的系统发育（Cairns, 1984; 1987），而是那些基于明显的、容易识别的字符来分组或区分属或属群的字符。因此，钥匙是人造钥匙，但在其组织中反映了凯恩斯（1984;1987）提出的许多系统发育划分。因此，两个键中的属的顺序大致是系统发育的，按派生程度降序排列。在表键中使用的字符的顺序是由它们区分分类群的能力和它们的易识别性决定的：比较保守和容易识别的字符从左到右排列。第15和10个字符都是基于外部骨骼字符；字符6-8要求观察树枝的横截面或纵剖面；9号字符最好借助扫描电子显微镜观察。每个角色都将简要讨论；在凯恩斯可以找到所有结构的插图和定义（1983a; 1983b; 1986a; 1986b；表1）。胃孔和趾状孔的协调性的增加被认为是针虫科的一个主要进化趋势（Cairns, 1987）：缺乏协调性被认为是最少的衍生状态，而循环系统排列被认为是最多的衍生状态。趾孔和胃孔的排列
Dichotomous and tabular keys to the 23 genera, 2 subgenera, and 5 species groups of the Stylasteridae are presented. The keys stress easily recognized external skeletal characters, most of which can be seen using a dissecting microscope, such as: coordination of dactylopores and gastropores, presence or absence of gastroand dactylostyles, cyclosystem orientation, dactylopore spine shape, ampuUar position, gastropore tube shape, dactylopore tube length, and coenosteal texture. Each of these characters is briefly discussed in the context of its discriminating power and its phylogenetic value. Two new terms are introduced to characterize dactylopore tubes: axial and peripheral. Numbers of valid species for each genus and their geographic and bathymetric ranges are listed. Two hundred twenty-four stylasterid species are considered to be valid, including 24 exclusively fossil species. Stylasterids are cosmopolitan, but insular, in distribution, ranging from 0-2,789 m. This is the third of an originally conceived two part series, the first part being the description of the stylasterid genera (Cairns, 1983b), the second part a phylogenetic analysis of those genera (Cairns, 1984). However, faced with the need to identify a large collection of stylasterids following a 2-year hiatus from their study, I found it useful to construct and herein publish both dichotomous and tabular keys to the genera of the family. Such a tabular key could have been extracted from the coded data matrix published in part 2 (Cairns, 1984: 52-53, appendix 2); however, those data were not presented in a fashion that allowed easy interpretation or ready use as a key. The aim of these keys is to provide an efficient and accurate method to identify and compare stylasterid genera using the most easily recognized characters. The characters used are therefore not necessarily the most important phylogenetically (Cairns, 1984; 1987), but those that group or distinguish genera or groups of genera based on obvious, easily recognized characters. The keys are therefore artificial keys, but reflect in their organization many of the phylogenetic divisions suggested by Cairns (1984; 1987). The order of the genera in both keys is therefore roughly phylogenetic, in descending order of degree of derivation. DISCUSSION OF CHARACTERS USED IN THE TABULAR KEY The order of the characters used in the tabular key was determined both by their ability to discriminate taxa and their ease in recognition: the more conservative and easily recognized characters are listed from left to right. Characters 15 and 10 are all based on external skeletal characters; characters 6-8 require observations of a cross or longitudinal section of a branch; and character 9 is best viewed with the aid of scanning electron microscopy. Each character will be briefly discussed; illustrations and definitions of all structures can be found in Cairns (1983a; 1983b; 1986a; 1986b; Table 1). The increase in coordination of gastropores and dactylopores is considered to be a major evolutionary trend within the Stylasteridae (Cairns, 1987): a lack of coordination is considered to be the least derived state and the cyclosystem arrangement the most derived. The arrangement of dactylopores and gastropores