Astiotrema karachiensis Bilqees, Khatoon & Khan, 2002

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 : 57-58

Astiotrema karachiensis Bilqees, Khatoon & Khan, 2002 n. comb.

( Figs. 26 & 27 )

(Syn.: Astioglossimetra karachiensis Bilqees, Khatoon & Khan, 2002 n. syn.)

Record (see Table 1 ): 1. Bilqees et al. (2002).

Remarks: Astiotrema karachiensis , described by Bilqees et al. (2002) from off the Karachi coast of Pakistan as Astioglossimetra karachiensis , is easily distinguished from other species of Astiotrema as it represents the only recognized species reported from a marine host, the green sea turtle, Chelonia mydas . While we noted earlier that the green sea turtle, C. mydas , was a “suspicious habitat/name” as a host for A. hanumantharai (= A. odhneri ) and in need of confirmation, herein it is considered a valid host species for A. karachiensis . Regardless of the marine environment of A. karachiensis , it is very closely related to A. odhneri in almost every morphological feature; however, some morphological differentiation should be taken into consideration to avoid overlap with A. odhneri since these particular features undergo a wide range of variation in A. odhneri . These differences include: (i) an oral sucker distinctly larger than the ventral one in A. karachiensis vs suckers roughly equal in size in A. odhneri ; (ii) A. karachiensis has a conspicuous muscular esophagus vs A. odhneri which possesses a straight, longer and thinner one; and (iii) in A. karachiensis , the anterior limit of the vitelline field is at the level of the intestinal bifurcation and is thus anterior to the level of the ventral sucker, whereas in A. odhneri it is either anterior to the level of the ovary or extends further to reach the level of the anterior margin of the ventral sucker, but it does not reach the level of the intestinal bifurcation.

Given the comprehensive review and newly added morphological data provided herein, we present below a key to the 8 species of Astiotrema (sensu stricto) we now recognize within this genus.

Figures

FIGURES 26 & 27. Astiotrema karachiensis Bilqees, Khatoon & Khan, 2002 n. comb. 26. A. karachiensis, dorsal view, redrawn from Bilqees et al. (2002, fig. 1). 27. A. karachiensis, ventral view, redrawn from Bilqees et al. (2002, fig. 3). Abbreviations: AT, anterior testis; Ce, cecum; CP, cirrus-pouch; Es, esophagus; GP, genital pore; OS, oral sucker; Ov, ovary; Ph, pharynx; PP, pars prostatica; PT, posterior testis; SR, seminal receptacle; SV, seminal vesicle; Ut, uterus; VF, vitelline follicle; VS, ventral sucker. Scale bars: Fig. 26 = 500 µm; Fig. 27 = 500 µm.