Schwenkiella orietanlis Singh and Agarwal, 1997 (PLATE-XXVII-XXVIII) Host : Periplaneta americana Locality : Meerut Location : Intestine No. of hosts examined : 250 No. of hosts found infected : 200 Female The body of the worm is elongated, cylindrical, striated and measures 2.20-2.22 mm in length and 0.24-0.26 mm in width. The first annule is 0.43-0.44 mm wide and 0.12-0.15 mm in length. The oral opening is surrounded by eight well developed labial papillae. The mouth opens into the buccal cavity which is 0.16-0.18 mm wide and 0.12-0.14 mm deep. The buccal cavity is lodged in the first annule. The armature of buccal cavity is cuticular, hard, made up of triangular base having elongated cornua, infolded distally. The size of base is 0.05-0.06 x 0.04-0.05 mm. Length of cornua is 0.11-0.15 mm. Buccal cavity is followed by an oesophagus consisting of a corpus, short isthmus and a vulvular bulb. The corpus is 0.27-0.29 mm in length and 0.034-0.045 mm in width. The isthmus is short measuring 0.013-0.016 mm in length and 0.029-0.033 mm in width (less wider than corpus). The vulvular bulb is rounded, muscular 0.11-0.12 mm in length and 0.13-0.14 mm in width. The intestine enlarged anteriorly to form a well formed cardia. The nerve ring is at 0.16-0.17 mm from the head end. The excretory pore is
present in the post-oesophageal region and opens at 0.43-0.46 mm from head end. In this species the lateral alae are absent which as also reported by Singh and Agarwal (1997). The cuticle is striated almost throughout the length of the body but the striations are clear in the anterior region only upto the excretory pore. The number of striations and interstrial zone in the annulations are different at different levels of the body. Interstrial zone is 0.007-0.0085 mm in the anterior region i.e., upto the oesophageal bulb. This region has a single striation. Six striations are present at the level of oesophageal bulb and the interstrial zone varies from 0.003-0.004 mm in length. From behind oesophageal bulb upto vulva, the interstrial zone ranges from 0.004-0.005 mm and the number of striations ranges from 2-5. However, the interstrial zone from vulva to anus ranges from 0.007-0.008 mm and the number of striations in each annule ranges from 1-2. The ovaries are two, the anterior flexture reaching near the base of cardia and the posterior flexture in the region of hind gut then turns upwards but never goes beyond anus. The vulva is equatorial, situated at about 1.10-1.13 mm from the head end. The vagina is muscular and directed anteriorly. The vaginal musculature consists of outer circular muscles and inner longitudinal muscles. The vagina open into a sac like spermatheca having gladular walls for the storage of sperms. The uteri are divergent filled with the segmented eggs. The eggs are ellipsoidal, double walled and are 0.062 -
0.065 mm long and 0.042-0.045 mm wide. The anus is at 0.58-0.59 mm from posterior end. The tail is filiform, pointed and measuring 0.45-0.47 mm long. Male : Not Known Difference in various measurement of body of the worm from original description of Singh and Agarwal (1997) is given in Table 15. CYTOTAXONOMY The detailed karyotype analysis of pachytene chromosme is appended in the Table 16. Idiogram was prepared based on chromosome length. The karyotype in S. orientalis Singh and Agrawal, 1997 is divisible into three major categories, first chromosme subtelocentric, third chromosome submetacentric and III rd, IV th, V th chromosomes are metacentric. All chromosomes have heterochromatic and euchromatic region in different proportions. The total length of the chromosome complement of worm is 0.0214 mm. The length of chromatin complement of all five chromosomes ranges from 0.0021-0.0070 mm. The centromeric indices were found to be variable in all the five chromosomes being highest in IV th chromosome (43.33%) and lowest in the I st chromosome (21.43%). The centromeric index was found to be 41.81% in IInd crhomosome, 35.13% in IIIrd chromosome and 42.27% in Vth chromosome. The average length of the chromosome in the worm is 0.00428 mm. with 31.43 S% and 30.42 TF%.
DISCUSSION Schwenkiella robustum (=Aororus (Thelastoma robustum) Leidy, 1850) was first described by Leidy, 1850 from the intestine of a lamellicorn insect and was placed by her in the subgenus Thelastoma of the Genus Aororus. Later she raised the subgenus Thelastoma to a full generic rank. Leidy's description was not accompanied with any figure and this worm has not apparently been described by any other worker until 1938 when Christie redescribed Thelastoma robustum with a remark on other genera of this family. Later workers like Schwenk, Travassos etc. doubted the inclusion of specimens of Thelastoma having attenuated and filliform tail, excretory pore posterior to the base of oesophagus, in the genus Thelastoma. Basir (1956) resolved this doubt and established a new genus in the family Thelastomatidae to accommodate the specimens of Thelastoma having attenuated tail and post-oesophageal excretory pore. The detailed generic diagnosis of the worm is : Female with mouth opening surrounded by eight labial papillae. Buccal cavity short and may or may not be armed with three tooth like projections. Oesophagus short, about one-sixth to one-eighth of body length, consisting of a more or less cylindrical corpus, a short isthmus and a valvular bulb. Tail attenuated filiform. Excretory pore posterior to base of oesophagus, vulva at about middle of the body. Ovaries two, uteri divergent. Eggs oval to ellipsoidal.
To the best of my knowledge following species are known under the genus Schwenkiella viz ; 1) S. robustum (Leidy, 1850) Basir, 1956 from the alimentary canal of Osmoderma scabra and Xyloryctes satyrus at United States of America. 2) S. icemi (Schwenk, 1926) Basir, 1956 from the intestine of Periplaneta americana, P. brulleau and Barata selvengen from Brazil, North India and U.S.A. 3) S. indica Rao and Rao, 1966 from the intestine of Corydia sp., at Hyderabad. 4) S. welchi Farooqui, 1968 from the intestine of Periplaneta americana at Aurangabad. 5) S. aurangabadensis Farooqui, 1970 from the intestine of Periplaneta americana at Aurangabad. 6) S. basiri Parveen and Jairajpuri, 1980 from intestine of Periplaneta americana at Aligarh. Besides these, Basir (1956) placed one more species, S. Iongicaudata (Meyer, 1896) Basir, 1956 under this genus but it is still under species inquirenda as there was no mention about the position of excretory pore in the original description of Meyer (1896). Rao and Rao (1966) included this species under the genus Schwenkiella. Later Farooqui (1968) and Parveen and Jairajpuri (1980) gave no mention about this species.