Surface ultrastructure and the mitochondrial gene rrnl of Parachristianella indonesiensis Palm, 2004 (Trypanorhyncha: Eutetrarhynchidae) with the amended generic diagnosis

Otobothrium muscatense n. sp. (Trypanorhyncha: Otobothriidae) from Rhabdosargus sarba (Forsskål) (Sparidae), with new locality records of larval trypanorhynchs off the Sultanate of Oman

In the evaluation of the larval trypanorhynch fauna off the Sultanate of Oman, a total of 188 bony fishes belonging to 16 species were studied, which led to the description of a new species with the establishment of new host and locality records. A new otobothriid species, Otobothrium muscatense n. sp., is described from Rhabdosargus sarba (Forsskål). Based on scolex morphology and tentacular armature, the new species closely resembles the small-sized Otobothrium Linton, 1890 species described as Otobothrium cysticum (Mayer, 1842) and O. crenacolle Linton, 1890. However, it differs from them in the basal armature by a more robust shape of the first principal and the triangular shape of the billhooks as well as by the retractor muscle originating in the posterior part of the tentacle sheath, attaching to a thickening of the tentacle sheath wall, with a muscular branch continuing and attaching at front part of the bulb. It differs from the other species of Otobothrium by size, the combination of six principal hooks and a single intercalary hook in the metabasal armature, and the plane of reflection through the tentacle surfaces. New locality records of the tentaculariids Nybelinia indica Chandra, 1986, Heteronybelinia yamagutii (Dollfus, 1960), Tentacularia coryphaenae Bosc, 1797, and Mixonybelinia lepturi Palm, 2004, together with the lacistorhynchids Pseudogrillotia multiminacantha Palm, 2004 and Callitetrarhynchus gracilis (Rudolphi, 1819), and the pseudotobothriid Parotobothrium balli (Southwell, 1929) off the Muscat region are established. Of the reported species, especially P. multiminacantha and M. lepturi occurring in Trichiurus lepturus L. further demonstrate the relatedness between the Indonesian and the northwestern Indian Ocean fauna, increasing the number of joint records between Indonesia and Omani waters to 14 species.

Genetic identity of eutetrarhynchids from the Persian Gulf, with intraindividual and intraspecific variability of Prochristianella butlerae Beveridge, 1990

The examination of the two batoid species, Pastinachus sephen (Forsskål) and Himantura gerrardi (Gray), resulted in a morphologic identification of the five eutetrarhynchid species, namely Parachristianella indonesiensis Palm, 2004 reported for the first time from Himantura gerrardi, Pa. monomegacantha Kruse, 1959, Prochristianella clarkeae Beveridge, 1990, Pr. butlerae Beveridge, 1990 and Dollfusiella spinulifera (Beveridge et Jones, 2000). By sequencing the partial 28S rDNA and calculating the genetic distances between the morphologically identified specimens from the Persian Gulf and their allopatric morphological conspecifics as well as using a phylogeny, the specimens of the Persian Gulf were considered as the allopatric conspecifics of Parachristianella indonesiensis, Pa. monomegacantha and Prochristianella clarkeae. Since the specimens of Dollfusiella from the Persian Gulf and D. spinulifera from Australia had a high genetic distance and placed in two separate clades, the Iranian specimens of Dollfusiella were treated as the cryptic species of D. spinulifera. Following the treatment of Prochristianella macracantha Palm, 2004 as the synonym of Pr. butlerae Beveridge, 1990, it was also expressed that although Pr. butlerae appeared to be a variable species in terms of its metric data, there was an identical oncotaxy in all the conspecifics. A detail examination of the specimens from the Persian Gulf as well as Australian voucher specimens revealed a great intraindividual and intraspecific variability in this species. Since, the sequence information is only available for the Iranian specimens and there is no possibility to evaluate the genetic distance and their monophyly, we consider these two allopatric populations as one species.