Mawsonascaris parva sp. nov. (Nematoda: Ascaridida) from the Arabian whipray Himantura randalli Last, Manjaji-Matsumoto et Moore (Rajiformes: Dasyatidae) off the coast of Iraq

Abstract

Mawsonascaris parva sp. nov. collected from the Arabian whipray Himantura randalli Last, Manjaji-Matsumoto et Moore (Rajiformes: Dasyatidae) off the coast of Iraq is described and illustrated using light and scanning electron microscopy. The new species differs from its congeners by its small body size (8.11-18.2 mm long), the absence of an intestinal caecum, the slightly unequal spicules (left and right spicule 1.08-2.50 mm and 0.98-2.01 mm long, respectively, representing 12.1-13.7% and 10.1-12.1% of body length), the number and arrangement of male caudal papillae (13-14 pairs in total, arranged as: 7-8 pairs of precloacal, 1 pair of double paracloacal and 5 pairs of postcloacal) and the presence of a single, median precloacal papilla. Thus, a total of six species of Mawsonascaris are now known and this is the first species of this genus recorded from species of Himantura.

Morphological variability and molecular characterization of Mawsonascaris australis (Johnston & Mawson, 1943) (Nematoda: Ascaridoidea: Acanthocheilidae) from the brown guitarfish Rhinobatos schlegelii Müller & Henle (Rhinopristiformes: Rhinobatidae)

“…However, in the present study, in one individual, we found the left spicule to be only approximately 1.2 times longer than the right. The relative length of the left and right spicules is a diagnostic morphological character for distinguishing and identifying species of this genus (Sprent, 1990; Ali et al ., 2012; Li et al ., 2012). The molecular analysis showed a low level of nucleotide variation in the ITS (only 0.10% nucleotide divergence) and cox 1 sequences (only 1.04–2.08% nucleotide divergence) between the two different morphotypes, which is far lower than the interspecific nucleotide variations between M. australis and P. rajae / P. argentinensis recorded in GenBank (14.1% nucleotide differences in the ITS region; >30.0% nucleotide differences in the cox 1 region).…”

“…Species of Mawsonascaris Sprent, 1990 are rare ascaridoid nematodes, occurring in the digestive tract of elasmobranchs (Sprent, 1990; Ali et al ., 2012; Li et al ., 2012). To date, only six species have been reported, namely M. australis (Johnston & Mawson, 1943), M. laymani (Mozgovoy, 1950), M. pastinacae (Rudolphi, 1819), M. zhoui Li, Xu & Zhang, 2012, M. myliobatum (Yin & Zhang, 1983) and M. parva Ali, Zhang, Al-Salim & Li, 2012, from the Atlantic Ocean, Arabian Gulf, and Australian and Chinese waters (Johnston & Mawson, 1943; Mozgovoy, 1950; Yin & Zhang, 1983; Sprent, 1990; Ali et al ., 2012; Li et al ., 2012). During a helminthological survey of Chinese marine fishes, several nematode specimens, identified morphologically as M. australis, were collected from the brown guitarfish Rhinobatos schlegelii Müller & Henle (Rhinopristiformes: Rhinobatidae) in the Taiwan Strait.…”