拟腹吸鳅属鱼类颏吸附器的扫描电镜观察及其亚属划分

ULTRASTRUCTURAL OBSERVATION ON THE CHIN ADHESIVE APPARATUS AND SUBGENUS DIVISION OF PSEUDOGASTROMYZON

扫描电镜下，构成拟腹吸鳅鱼类颏吸附器的若干条皮脊均由许多分别根植于单个上皮细胞表面的爪形突组成。爪形突高１５～２０μｍ，横截面常呈椭圆形，长短轴的４～５μｍ，易脱落，也可增生。它们可能具有吸附基质表面、保护周围味蕾等功能。由于爪形突分布部位的不同和所组成皮脊的形态差异，可明显地分为叠波型和品字型两类。这两类吸附器的种类间同时在味蕾分布、口角须结构和背鳍条及腹鳍条数目等方面也存在相应的差异，代表了两个独立演化的自然类群。本文把腹吸鳅属分成两个亚属，将其中颏吸附器呈品字型的三个种和亚种分离出来，成立品唇吸鳅亚属（Ｌａｂｉｇａｓ－ｔｒｏｍｙｚｏｎ），其他是叠波型的种类则归属指名亚属（Ｐｓｅｕｄｏｇａｓｔｒｏｍｙｚｏｎ）。

The ultrastructure of the chin adhesive apparatus of Pseudogastromyzon was studied with scanning electron microscope. The apparatus are composed of several dermal ridges which consist of unculi arising from single epidermal cells respectively. The unculi possibly serve as adhesive devices to the substrata and as protective organs for the associated taste buds. Two types of adhesive apparatus, termed wave-shaped and club-shaped, can be easily distinguished according to the differences of the ridges. Relative differences between the species of these two types are shown in the distribution of taste buds, maxillary barbels, dorsal rays and ventral rays. These differences indicate that the Pseudogastromyzon can be divided into two monophyletic subgroups. A new subgenus Labigastromzon, including three species possessing club-shaped apparatus, is proposed. The others possessing waveshaped apparatus belong to the subgenus Pseudogastromyzon. Labigastromyzon, subgen. nov. Subgen-type: Crossostoma fangi Nichols 1931 Similar to Pseudogastromyzon in general form. But its chin adhesive apparatus clubshaped ; two papillae on the base of maxillary barbels ; branched dorsal rays 8-9 ; branched ventral rays 8. distribution: China: Hanjiang River, Nongjiang River, Zhujiang River, Xiangjiang River.