ABSTRACT
A new species, Alexandercestus masoumehae n. sp., is described from the sicklefin lemon shark, Negaprion acutidens (Rüppell), from the Iranian coast of the Gulf of Oman. The new species is the third in this genus, all parasitizing species of Negaprion Whitley. Based on morphological characters and scanning electron microscopy the new species is different from its congeners of in a combination of characters including total length, terminal proglottid length, cirrus sac length, and genital pore position. Compared to Alexandercestus gibsoni Ruhnke & Workman, 2013 and A. manteri Ruhnke & Workman, 2013 the specimens of the new species are smaller (7.08-8.5 mm), with a smaller terminal proglottid length to width ratio (1:0.7-1.3 vs. 1.4-3.2:1 and 1.2-3.1:1, respectively), and have a more anterior genital pore (70-73% of proglottid length vs. 42-66% and 41-65%, respectively). In addition, A. masoumehae possesses less foliose bothridia compared with A. gibsoni, and more densely packed vitelline follicles in comparison with A. manteri. The SEM examination of the scolex in the new species reveals a specific pattern of microtriches adding new details in our understanding of the surface morphology of members of Alexandercestus. Finally, the new species increases the total number of described tapeworm species from N. acutidens to five and the described tapeworms in the Persian Gulf and Gulf of Oman region to 65.
ABSTRACT
The microthrix pattern of larvae of Pseudogilquinia thomasi (Palm, 2000) is described for the first time using scanning electron microscopy. The surface ultrastructure of this species consists of three main forms of microtriches: papilliform filitriches, acicular filitriches and quadridigitate to octadigitate palmate spinitriches. The bothria are covered with palmate spinitriches interspersed on some parts with papilliform filitriches. Palmate spinitriches with papilliform, acicular and capilliform filitriches adorn the pars vaginalis and at the anterior part of the pars bulbosa, there is a transition zone in which the palmate spinitriches are replaced by papilliform to acicular filitriches towards the end of the scolex. ANOVA tests with Duncan's post hoc analyses revealed that there are significant differences in the length of spinitriches and their prongs, whether on the surfaces of the bothria or on the surfaces of the scolex peduncle. Callitetrarhynchus gracilis Pintner, 1931 is the second lacistorhynchid species for which surfaces of the segments were examined and the occurrence of large structures called scutes are reported for the first time from this species. There were also significant differences in the base length as well as height of the scutes in different parts of the strobila. In addition to describing the surface ultrastructures of the two lacistorhynchid species, all the available information on the microtriches within the family Lacistorhynchidae is reviewed herein and generic diagnoses related to microtriches are amended.
