Astiotrema ranarum ( Mehra & Negi, 1926 ) Fotedar, 1971

Karar, Yasser F. M., Blend, Charles K., Dronen, Norman O. & Adel, Asmaa, 2021, Towards resolving the problematic status of the digenean genus Astiotrema Looss 1900: An updated concept and revision of species composition for Astiotrema (sensu stricto), Zootaxa 4991 (1), pp. 36-72 : 48-50

Astiotrema ranarum ( Mehra & Negi, 1926) Fotedar, 1971

( Figs. 12–14 )

(Syns.: Centrovitus pentadelphi Bhalerao, 1926 ; Tremiorchis ranarum Mehra & Negi, 1926 ; Tremiorchis mehrai Rai, 1962 ; Tremiorchis vitelloconfluentum Rai, 1962 ; Tremiorchis attenuatus Karyakarte, 1973 ; Tremiorchis tigrinarum Sinha, Sahay & Prasad, 1974 ; Tremiorchis mathuraensis Swaroop & Jain, 1976 ; Tremiorchis tigrinarum andersoni Lal, 1977 n. syn.; Tremiorchis spiniphlyctis Kalyankar & Palladwar, 1978 ; Astiotrema siddiqii Lal & Prasad, 1980 n. syn.; Tremiorchis jamshedpurensis Hasnain, 1989 n. syn.; Tremiorchis fatimae Bilqees & Khan, 2003 n. syn.)

Records (see Table 1 ): 1. Bhalerao (1926); 2. Mehra & Negi (1926, 1936); 3. Verma (1930); 4. Singh (1954); 5. Bhardwaj (1962); 6. Rai (1962); 7. Agrawal (1968); 8. Ali & Karykarte (1970); 9. Dwivedi & Chauhan (1970); 10. Mukherjee & Ghosh (1970); 11. Fotedar (1971); 12. Sinha & Sahay (1971); 13. Pandey (1973); 14. Rao (1974); 15. Sinha et al. (1974); 16. Bhutta & Khan (1975); 17. Swaroop & Jain (1976); 18. Khan & Haksar (1977); 19. Lal (1977); 20. Singh (1977); 21. Kalyankar & Palladwar (1978); 22. Singh & Sinha (1979); 23. Karyakarte & Baheti (1980); 24. Lal & Prasad (1980); 25. Hafeezullah & Dutta (1981); 26. Hasnain (1989); 27. Rajendran & Janardanan (1993); 28. Bilqees & Khan (2003); 29. Pandey & Agrawal (2013); 30. Pandey et al. (2013); 31. Hemalatha et al. (2015).

Remarks: Bhardwaj (1962) examined T. ranarum and reported intra-specific variations and abnormalities including (i) differences in size of body and organs, (ii) minor differences in sucker ratio, (iii) presence or absence of a prepharynx, (iv) slight changes in extent of intestinal ceca, cirrus-pouch and vitellarium, (v) confluent nature of the vitelline follicles, (vi) differences in position, size and shape of gonads as well as degree of lobulation of testes, (vii) slight variations in size and shape of the egg, (viii) differences in the posterior extent of the cirrus-pouch relative to the ventral sucker (either more dorsal or lateral to it), and (viii) degree and posterior extent of spines on the body. In light of the work of Bhardwaj (1962), Mukherjee & Ghosh (1970) considered both T. mehrai and T. vitelloconfluentum as synonyms of T. ranarum and transferred T. varanum into Astiotrema as A. varanum (see above). Pandey & Agrawal (1981) presented a detailed discussion and review of Tremiorchis . This study focused on the slight morphological spectrum observed in some features which previously were considered differential characters between several species of Tremiorchis . Pandey & Agrawal (1981) attributed the observed variations noted by Bhardwaj (1962) to the degree of maturity of the worm, poor sample size and errors in preparation of parasites, particularly fixation. Based on the invalidity of characterizing species based on such slight variations, Pandey & Agrawal (1981) accepted the synonymy of T. mehrai and T. vitelloconfluentum with T. ranarum and also synonymized T. tigrinarum , T. mathuraensis and T. spiniphlyctis with T. ranarum , the only representative of Tremiorchis . In another revision of Tremiorchis, Hafeezullah & Dutta (1981) referred to the synonymy of T. attenuatus , T. tigrinarum and T. mathuraensis with T. ranarum as an indicator of the monotypy of Tremiorchis . To explain the variability among these four species, Hafeezullah & Dutta (1981) attributed these variations to human error during sample preparation as represented by the different states of contraction or relaxation among the specimens, evidence of excessive pressure applied and the incorrect orientation of the fluke during the mounting process. Fotedar (1971) synonymized Tremiorchis with Astiotrema and recognized T. ranarum as A. ranarum , and although this synonymy was rejected by Pojmańska (2008), we accept it based on the results of Besprozvannykh et al. (2015) and similarities with life-cycle patterns elucidated by Rajendran & Janardanan (1993).

Astiotrema ranarum is easily characterized as follows: (i) oral sucker slightly smaller than ventral sucker, (ii) vitelline fields short and extend from level of ventral sucker to posterior limit of pretesticular level, (iii) ceca short and terminate at level of anterior testis, (iv) ovary either contiguous with ventral sucker or posterior to it by a small distance and (v) esophagus long and straight. Lal (1977) described a new subspecies, T. tigrinarum andersoni , based on what was interpreted as intra-specific morphological variations observed in specimens of T. tigrinarum (= T. ranarum ) from the intestine of the smooth-sided or spotted toad, Rhaebo guttatus (Schneider) (Syn. Bufo anderssoni Melin ) ( Anura : Bufonidae ). Hasnain (1989) added T. jamshedpurensis for specimens gathered from the intestine of the common or Indian skittering frog, E. cyanophlyctis ( Anura : Dicroglossidae ), in Jamshedpur, Jharkhand, India. Bilqees & Khan (2003) described T. fatimae for specimens collected from the small intestine of the same host, E. cyanophlyctis , in Karachi, Sindh, Pakistan, and distinguished it from T. ranarum by its longer body, suckers of slightly smaller size and its slightly larger eggs. In light of the wide range of intra-specific variability observed in T. ranarum ( Bhardwaj 1962; Hafeezullah & Dutta 1981; Pandey & Agrawal 1981) and the common geographical distribution as well as records from common hosts, we interpret T. tigrinarum andersoni , T. jamshedpurensis and T. fatimae as synonyms of T. ranarum . Lal & Prasad (1980) erected A. siddiqii for two specimens collected from the intestine of E. cyanophlyctis in Patna, Bihar, India. We found this species morphologically to be identical to A. ranarum except in having an indistinct esophagus and the anterior extent of the vitellarium is to the level of the intestinal bifurcation. We also note the poor sample size and the contracted status of their specimens (see Lal & Prasad 1980, fig. 1). Specifically, it seems that the anterior portion of the body is deformed and more contracted, producing a shortened esophagus, the ventral sucker and intestinal bifurcation overlap, and both the ventral sucker and vitelline fields are positioned more anteriorly. In addition, this species shares the same host group (dicroglossid frogs) and locality ( India) with A. ranarum . Thus, we consider A. siddiqii another synonym of A. ranarum .

Astiotrema ranarum is morphologically similar to A. impletum , but the latter differs by having (i) an oral sucker much larger than the ventral sucker rather than vice versa, (ii) the anterior extent of the vitellarium reaching the level of the pharynx and not the level of the ventral sucker, (iii) a large seminal vesicle occupying almost the entire cirrus-pouch and not a small one occupying about 1/3 of it, (iv) ceca ending immediately posterior to or near the level of the posterior testis vs in the area anterior to the anterior testis, (v) a sigmoid esophagus vs a straight one, and (vi) A. impletum is known from fish (globe fish), reptiles (monitor lizards) and anurans (Asian common toad), whereas A. ranarum is restricted to amphibians only.

Figures

FIGURES 12–14. Astiotrema ranarum (Mehra & Negi, 1926) Fotedar, 1971 revealing some slight intra-specific variations. 12. A. ranarum (Syn. Centrovitus pentadelphi Bhalerao, 1926), dorsal view, redrawn from Bhalerao (1926, fig. 1). 13. A. ranarum (Syn. Tremiorchis ranarum Mehra & Negi, 1926), dorsal view, redrawn from Mehra & Negi (1926, fig. 2). 14. A. ranarum (Syn. Tremiorchis mehrai Rai, 1962), dorsal view, redrawn from Rai (1962, p. 382).Abbreviations: AT, anterior testis; Ce, cecum; Ci, cirrus; CP, cirrus-pouch; ED, ejaculatory duct; EP, excretory pore; Es, esophagus; EV, excretory vesicle; GP, genital pore; MG, Mehlis’ gland; OS, oral sucker; Ov, ovary; Ph, pharynx; PP, pars prostatica; PT, posterior testis; SR, seminal receptacle; SV, seminal vesicle; Ut, uterus; VD, vitelline duct; VF, vitelline follicle; VR, vitelline reservoir; VS, ventral sucker. Scale bars: Fig. 12 = 500 µm; Fig. 13 = 500 µm; Fig. 14 = 500 µm.