A morphological and molecular reinvestigation of Janickina pigmentifera (Grassi, 1881) Chatton 1953 – an amoebozoan parasite of arrow-worms (Chaetognatha)

Abstract

Amoebozoan parasites of arrow-worms (Chaetognatha) were isolated from their hosts living in plankton of the Bay of Villefranche (Mediterranean Sea). Based on the light microscopic characters, the amoebae were identified as Janickina pigmentifera (Grassi, 1881) by their limax locomotive form and due to the presence of the intracellular symbiont, Perkinsela amoebae, surrounded by a layer of pigment granules. Sequences of the 18S rRNA gene of both J. pigmentifera and its symbiont were obtained for the first time. The molecular phylogenetic analyses of 18S rRNA gene placed J. pigmentifera within the genus Neoparamoeba, a taxon also characterized by the presence of a symbiont, known as Perkinsela amoebae-like organism (PLO). The 18S rRNA gene sequence of P. amoebae from J. pigmentifera grouped with the sequences of 18S rRNA genes of PLOs from Neoparamoeba branchiphila and Neoparamoeba invadens. The first photo documentation of the light microscopic features of J. pigmentifera, such as locomotive form, the morphology of the nucleus and P. amoebae have been provided. The new results support the affinity of J. pigmentifera with the family Paramoebidae suggested previously based on the presence of PLO. In contrast to Janickina, typical members of Paramoebidae (Neoparamoeba and Paramoeba) have a flattened, dactylopodial locomotive form. This discrepancy in morphology can be explained by the obligate parasitic lifestyle of Janickina.

Coronamoeba villafranca gen. nov. sp. nov. (Amoebozoa, Dermamoebida) challenges the correlation of morphology and phylogeny in Amoebozoa

“… 38 , 39 ). Furthermore, cylindrical monopodial locomotive forms were reported for the parasitic discosean genus Janickina 24 which turned out to belong to Dactylopodida according to molecular data 25 , and the variosean genus Schoutedamoeba described relatively recently 23 . Moreover, on a broader scale, in the presence of certain eruptive flow on anterior end of the cell the amoeba studied resembles amoeboid members of the Heterolobosea 27 , a lineage distant from Amoebozoa or Amorphea in general 1 .…”

“…Amoebae were isolated from the plankton sample collected at 'point B' (43.683 N, 7.317 E), a monitoring point in the Bay of Villefranche, in September 2019 using a plankton net. The sampling procedures were described in 25 . A portion of sampled material was diluted with filter-sterilized natural seawater and aseptically sorted using a binocular microscope.…”

“…Therefore, this species was transferred to a separate genus Janickina Chatton, 1953. Yet, a recent molecular investigation has shown that these amoebae indeed belong to Dactylopodida and branch with a clade comprising species of Paramoeba and Neoparamoeba , in spite of the differences in their locomotive morphology 25 . On a eukaryote-wide scale, it should be noted that a superficially similar morphotype is demonstrated by the amoeboid cells of Heterolobosea (Discoba).…”

Living in the cracks: Two novel genera of Variosea (Amoebozoa) discovered on an urban sidewalk

“…However, these morphological characters are few in number and vague in designation, making the isolates difficult to place taxonomically based on morphology alone. For example, limax body plans are present in all major groups of Amoebozoa: Tubulinea (Smirnov et al., 2011), Discosea (Blandenier et al., 2017; Kudryavtsev et al., 2022; Volkova & Kudryavtsev, 2021), and Evosea (Wichelen et al., 2016), as well as the amoeboid Excavate group Heterolobosea. Despite the presence of similar limax shapes in Heterolobosea, our amoebae lacked the characteristic eruptive movement of heterolobosean amoebae, which is a diagnostic morphological character strongly supported by molecular studies (Harding et al., 2013; Nikolaev et al., 2004).…”

Diversity and Distribution of Arrow Worms, Zooplankton Along the Mangaluru and Udupi Coast, Karnataka

“…A 10x handheld Microscope was used to observe and separate the chaetognaths. The taxonomic observations were made on the preserved samples under a compound microscope (OLYMPUS CK X 41) microscope using the keys of previous investigations (Kapp, H. and Pierrot-Bults, A.C., 1991, Volkova, E. and Kudryavtsev, A., 2021.) For quantitative analysis every specimen present in the collected samples were counted.…”