角突泥介虫(Ilyocypris angulata Sars)(介形亚纲)雄体的发现

DESCRIPTION OF A MALE ILYOCYPRIS ANGULATA SARS (CRUSTACEA: OSTRACODA)

本文报道了角突泥介虫(Ilyocypris angulata Sars)雄体的发现。对此雄体进行了详细的描述,论述了泥介虫属的生活方式,并讨论了介形类有三种生殖方式。

A male form of Ilyocypris ungulate Sars hitherto unknown to science, collectedfrom a small pool near Yueyang, Hunan, is described as follows. Shell in side view similar to that of the female, with the greatest heightnear theeye, and a little less than half the length. Dorsal margin nearly straight,but slightly concave in the middle. Ventral margin distinctly sinuated at thecenter. Anterior end slightly broader than posterior end; both ends rounded andarmed with denticles, but not as large as those of the female form. Each denticlebearing one sets at its tip. Shell surface covered with polygonal reticulations.Three lateral projections found on the upper part of each valve, with anteriorone situated beneath the eye; middle one being the largest, projecting beyond thecenter of the valve. Below these 3 projections, lower part of each valve with alongitudinal ridge. In dorsal view, body slightly narrower than that of the female,otherwise similar. Lateral projections easily observed on the sides of the shell.Greatest width of body less than the height, located just at the posterior projec-tions of the shell. Anterior and posterior ends narrowly rounded; two valvesnearly equal in length at both ends. Swimming setae of the antennule well-developed, with distal 2/3 extendingbeyond the tip of claws. First swimming sets of the antenna reaching the middleof claws; other five setae extending beyond the claws. Second thoracic leg pos-sessed of four podomeres, with the penultimate podomere undivided. Penultimate podomere of the posterior leg with two well-developed setae. Furcal ramus gentlycurved, similar to that of the female. Two slender and similar prehensile palpspointed at tips. Middle lobe of the hemipenis being the largest, trapezoid inform,with the distal-inner corner smallest. Ductus ejaculatorius long and slender,with about nineteen wreaths of supporting spines. Measurements Length 0.93mm, height 0.49mm, width 0.33mm. Remarks The material collected with a plankton net was found among theaquatic weeds along the shore of a small pond. As observed even from the pre-served specimens, the surface of the shell usually has Vorticella sp. and some speciesof diatoms attached on it indicating that it is probably not a burrowing form.