福建省一新种并殖吸虫 Paragonimus fukienensis sp.nov.的初步报告

A PRELIMINARY REPORT ON A NEW LUNG FLUKE, PARAGONIMUS FUKIENENSIS SP. NOV, (Class Trematoda: Family Troglotrematidae)

二十二年前作者中的一个(Tang,1940)曾从事福建省两种肺吸虫发育史的比较,一种称“林氏型”(Ringeri type)的是卫氏并殖吸虫(Paragonimus westermani),另一种当时称为“鼠型”(Rodent type)的是寄生于本省福清山区沟鼠及野鼠的肺吸虫。在陈心陶教授的怡乐村并殖吸虫专著(Chen,1940)发表之后,福建鼠体的肺吸虫被认为属于怡乐村并殖吸虫(P. iloktsuenensis)而該区“鼠型”的虫种区别的問题便认为已經解决了。近年来国內肺吸虫研究有不少新的发展,在云南,四川,江西以及东北省份新病区的发現。

Twenty-two years ago one of us (Tang, 1940) made a comparative study of two types of Paragonimus occurring in Fukien Province with regard to their developmental morphology and host relations. One of the lung fluke, designated as the 'ringeri' type, was later considered to belong to Paragonimus westermani, and the other, designated as the 'rodent' type was determined to be P. iloktsuenensis, when reference was made on Chen's monograph on that species in 1940. Since both worms occur in rodents and their distributions are so near as in the neighboring provinces they were presumably considered to be identical, without critical comparison of adult morphology. With the advancement of the knowledge of paragonimiasis in China after liberation, discoveries of new endemic areas and new species were witnessed, giving impetus for a more thorough determination of species in different areas. After reexamination of former mounted specimens secured from Futsing area since 1939 we were surprised to find significant differences exist between our specimens and the description of P. iloktsuenensis. A more thorough study and further comparisons were made with other described species of the genus, and it was considered that the form of Paragonimus occurring in Fukien is new to science. The name Paragonimus fukienensis sp. nov. is proposed.The adult worm measures 9.5-14.70mm. in length (average 12.12mm.) and 5.27-6.85mm. in width (average 6.11mm.). The body is somewhat convex on its dorsal and flat on its ventral side. The greatest width of the body lies on the level of acetabulums which is located about anterior 35-39% of the body length. The cuticle of the body is armed with small spines. The oral sucker is terminal with transverse diameter 0.77-0.91mm. (average 0.85mm.). The ventral sucker is smaller than the oral sucker, measuring 0.59-0.80 by 0.65-0.81mm. (average 0.73 by 0.74mm.). The pharynx is appressed to the oral sucker. It measures 0.36-0.40 by 0.40-0.47mm. (average 0.38 by 0.44mm.). The oesophagus is short, bifurcating into two intestinal caeca, which, after bending three or four times, extend to the posterior part of the body.Ovary is situated at some distance from the ventral sucker, usually on the left side. It measures 1.35-1.98 by 0.99-1.56mm. (average 1.58 by 1.27mm.). It is about twice the size as the ventral sucker. This organ possesses a central portion from which arise five or six main branches. They are either not divided or divided further into two or three subbranches. In form it is very characteristic and differs from that of P. iloktsuenensis in having less number of branches and in the presense of a distinct central portion. Chen(1940)described the ovary of this species as 'a much branched organ, of the nine measured eight are somewhat elongated and one somewhat globular. Branching is profuse and appears to occur on all sides'. The ovary of the present species more resembles that of P. kellicotti in possessing a central portion and that the main branches are distinct, but it is not so finely branched. According to Miyazaki (1939) the ovary of P. ohirai consists of clusters of branches. In form it resembles that of P. iloktsuenensit.The oviduct arises from the ovary. In a short distance, it meets with the seminal receptacle and Laurer's canal and then turns toward the ootype. Seminal receptacle is an oval or pear-shaped sac, measuring 0.20-0.26mm. by 0.13-0.16mm.. Laurer's canal possesses an expension at its base. Together with the seminal receptacle it opens directly to the oviduct. The structure of the receptacle-canal complex is another characteristics differing from that of other species. According to Chen the Laurer's canal of P. iloktsuenensis is 'distinctly connected with the receptacle only, This condition is true also with P. westermani on the basis of Kerbert's description and P. ohirai.' With the present species both seminal receptacle and Laurer's canal join together and open immediately to the oviduct. The seminal receptacle of P. iloktsuenensis is larger, measuring 0.285mm. (the smallest) to 0.385 by 0.243mm. (the largest) with an average of 0.333 by 0.169mm.. We have also observed the seminal receptacle and Laurer's canal of P. westermani in living specimens. The former organ is an oval sac, connected with the Laurer's canal on one side, while the latter is a slender tube, having no expansion at its base.The comparison with P. kellicotti is more difficult as Ward and Hirsch (1915) described both seminal receptacle and Laurer's canal from microscopical sections. The one similarity of the two species however is the expansion of Laurer's canal at its basal part. Its Laurer's canal is expecially long making a half circle around the region of Mehlis glands before turning dorsally and openning on the dorsal surface.Testes occupy the posterior one third of the body length. The left testis is 2.67-3.52mm long and 0.99-1.79mm. broad (average 3.01 by 1.24mm.). The right testis is 2.08-3.77mm. long and 1.24-2.57mm. broad (average 2.98 by 1.68mm.). The central mass is rather small, and about 5 or 6 branches take their origin from this central portion and extend posteriorward. The distal portion of each branch is usually expanded to form big lobes. Some braches often extend outside of the intestinal caeca. From the anterior part of each testis there arises a sperm duct, the vas efferens. It runs forward and meets with its mate usually on the right side of the body at the level of the ovary to form the vasa deferentia. The latter soon enlarges to form a seminal vesicle, which is a long tube 0.99-1.09mm. in length and 0.095-0.21mm. in width. This organ is not so long and characteristically curved as described for P. iloktsuenensis, but some specimens show constricted portion of the vesicle as mentional for that species. The seminal vesicle opens at the common genital atrium, which, in turn, is connected to the genital pore situated at the hind margin of theventral sucker.The oviduct after leaving the ootype, turns obliquely forward. After many windings and coils in the middle region of the body opposite to the ovary, it gradually enlarges itself and becomes a sac-like tube of voluminous size, and then narrows itself into a thin tube to open into the genital atrium and then the genital pore.The value of cuticular spines as a criterion for the differentiation of species has been discussed by different investigators. More recent studies indicated that they are important adult-characters for taxonomic purpose. The spinulation of P. fukienensis presents an unique character. In arrangement they are singly spaced in the portion of the body about anterior one-third or the part anterior to the ventral sucker, while on the posterior portion behind the acetabulum they appear as clusters of two-three, threeeight, two-fifteen etc. The intermediate regions occur on both sides of the acetabulum, where both forms exist.The single spines are larger. They vary greatly in size and shape. Some are lanceolate, others are oval, elongated, or broadly flat with rounded or serrated edges. Spines immediately behind the oral sucker are usually somewhat smaller. They appear as flat and narrow ones with a length of 0.028-0.034mm.. Some are even shorter. Such elongated spines are the predomineat ones all over the anterior part of the body; They increase in size, as our focus is directed more posteriorly. In the middle region between two suckers the length of the spines increase to about 0.039mm.On rare instances there appear in the immediate region behind or lateral to the oral sucker, spines much smaller than the above-described ones, with two in each cluster and the area is very restricted. Singly spaced spines appear also on the dorsal side. Their pattern of distribution is very similar to that on the ventral.Behind the acetabulum the spines appear in cluster form. It seems each spine split into 2-3, 4-5, smaller spines. In the region between the twe testes the phenomenon is most evident. Some clusters have more spines. 7-8 spines are often counted, but the majorities are 3-5 with 5 the commonest. Spines immediately behind the ventral sucker measure 0.022-0.034mm.. They are often 2-3 in a group: Those between two testes are variable in length measuring 0.014-0.047mm.. Spines behind the testes are more variable in form. They number 2-15 in each cluster. Their measurements range 0.013-0.047mm.. The small spines in each cluster are usually more separated and more acute in form. Very often in one cluster very short ones overlap with those which are much longer. On both lateral sides right and left, to the testes, narrow spines with longer dimensions are found, Those spines near to the posterior end of the worm are often smaller and shorter. They are often not typical in form, with points directed laterally instead of posteriorly. Their number also vary greatly from 3-5 in one cluster to as many as 12-15.The arrangement of cuticular spines in P. fukienensis is greatly different from P. iloktsuenensis in that it possesses spines, which are predominently singly spaced on the surface of the body anterior to the ventral sucker, and appear in clusters in the posterior part. For P. iloktsuenensis Chen(1940)described 'the spines on the ventral side between two suckers are in groups of two (rarely one) to as many as five or six,with two to four being the commonest, and on the ventral side between the two testes in groups of from two to about ten with five or six being the commonest'. There exists no doubt that the spinulation of these two species are different.With regard to P. ohirai its spines can also be distinguished from those of the present species in that they are arranged in groups of commonly five or six in a cluster between the two suckers and six to about ten between the testes, both on the ventral side. In form and shape they are more linear and pointed at one end. They also appear to be different in that each cluster has from two