Nematode epibionts on skin of the Florida manatee, Trichechus manatus latirostris

A survey for the presence of nematodes on the skin of the native Florida manatee, Trichechus manatus latirostris from Crystal River, Florida was conducted during annual manatee health assessments. A putative isolate of Cutidiplogaster manati (Diplogastridae) and two other nematodes belonging to the same family were recovered from mid-dorsal tail skin-scrapings from all sampled winter-collected healthy wild adult manatees during two successive years (2018–2019). Qualitative abundance estimates of these three species of diplogastrid nematodes suggest that an average wild Florida manatee adult might possess between 30,000 and 120,000 nematodes on its tail dorsum and that the entire body dorsum including the tail might possess 160,000–640,000 nematodes in roughly equal ratios. Attempts to culture these nematodes on a variety of different culture media were unsuccessful but examination of the mouth (stomatal) morphology suggests specialized feeding on microbes such as diatoms or predation on other nematodes. No skin lesions were observed during the 2018–2019 samplings suggesting that under normal conditions these nematodes are highly specialized free-living epibionts of the skin that are tightly bound to this niche and horizontally transferred between individual manatees in an analogous fashion to human skin mites (Demodex folliculorum and D. brevis). Molecular phylogenetic inferences using sequences of near full length SSU and D2–D3 expansion segments of LSU rRNA genes revealed a putative new morphospecies in Cutidiplogaster sister to C. manati that was monophyletic with several named Mononchoides species, and another putative new morphospecies that formed a clade with several undescribed species similar in appearance to Mononchoides as well as Tylopharyx, Eudiplogasterium, Paroigolaimella and Sachsia.

Molecular profiling of nematode associates with Rhynchophorus ferrugineus in southern Italy

A survey of nematodes associated with the red palm weevil Rhynchophorus ferrugineus was conducted in southern Italy in 2015 and 2016 in order to create a species inventory and obtain data about nematode biodiversity. A total of 70 insect samples (pupae and adults) were collected from infested Phoenix canariensis, Phoenix dactylifera, and Chamaerops humilis palms in three Italian Regions: sampling took place at 11 locations in Apulia, 1 in Basilicata, and 1 in Sardinia regions. Individual insects were dissected to determine nematode presence, and different nematode species were also recovered from red palm weevil cocoons collected at the sites in Apulia. Individual nematodes were molecularly identified by sequencing the ITS, D2-D3 expansion domains of the 28SrRNA gene and the mitochondrial COI and inferring the phylogenetic relationships. The insect-associated nematofauna identified belonged to the families Rhabditidae, Cephalobidae, and Diplogastridae. Just two nematode species, Teratorhabditis synpapillata and Mononchoides macrospiculum, were always found in association with adult insects and cocoons taken from all sampling sites. This paper reports on the biodiversity of the nematodes associated with R. ferrugineus and on current knowledge of the specific habitat of specialized and divergent entomophilic nematodes.

Acrostichus palmarum n. sp., a cryptic species separated from A. rhynchophori by molecular sequences and hybridisation tests

A new Acrostichus species is described based upon molecular sequence profiles and hybridisation testing. The new species, A. palmarum n. sp., had been previously described as local isolates (strains) of A. rhynchophori, i.e., an isolate recovered from Rhynchophorus cruentatus from South Florida (culture code RGD193) was designated as the type strain of A. rhynchophori, and other Central and South American strains (RGD194-196), recovered from R. palmarum were considered as conspecific regional isolates. However, additional sequencing of ribosomal DNA loci (near full-length of small subunit, full length of internal transcribed spacer and D2-D3 expansion segments of large subunit) and partial mitochondrial cytochrome oxidase subunit I gene and hybridisation testing suggested the independent species status of RGD194-196. Furthermore, two strains of A. palmarum n. sp., RGD194 and RGD195, showed partial reproductive isolation from each other, i.e., the fecundity of F1 progeny was obviously low, suggesting that geographical isolation within a widely-distributed species is occurring.