Heth pivari n. sp. (Nematoda: Ransomnematoidea: Hethidae) from the indigenous North American millipede Narceus gordanus (Spirobolida: Spirobolidae), with keys for worldwide Heth spp.

Abstract

Forty-four specimens of the millipede Narceus gordanus Chamberlin, 1943 (Spirobolida: Spirobolidae) were collected from Alachua, Citrus, Hernando, and Marion counties in peninsular Florida. Morphometric data were recorded for each. Nematodes were dissected from the intestine of each individual and sorted into morphotaxa. Heth pivari n. sp. (Oxyuridomorpha: Ransomnematoidea: Hethidae) was found in 33 (75%) of dissected N. gordanus and examined with brightfield, differential interference contrast, phase contrast and scanning electron microscopies. LSU rDNA sequences of representative males and females of H. pivari n. sp. were analyzed and compared to sequences of nematodes in the infraorder Rhigonematomorpha. Heth mauriesi, an introduced species, also was sequenced. Females of H. pivari n. sp. differ from those of other Heth spp. in having smooth, button-like somatic and cervical papillae and shallow, shield-like cervical collars. Males have slit-like or narrowed, rather than circular, stomal openings. Heth pivari n. sp. is the first species of this genus found in an indigenous millipede north of Mexico. Keys based on female cervical ornamentation are provided to differentiate the 52 known Heth spp.

Molecular identification of a new species of Rhigonema (Nematoda: Rhigonematidae) and phylogenetic relationships within the infraorder Rhigonematomorpha

“…Although some previous taxonomical studies provided 18S and/or 28S genetic data for diagnosis of species [5,17,18,[62][63][64], the molecular identification of Rhigonematomorpha nematodes remains in its beginning phase. BI and ASAP analyses based on the cox1 and cox2 sequences both supported species partition of R. sinense n. sp.…”

“… Philippines KY985469.1 KY985470.1 [ 64 ] Heth initiensis Rhinocricidae sp. Philippines KY985471.1 KY985472.1 [ 64 ] Heth pivari Narceus gordanus USA MK182092.1 MK182091.1 [ 18 ] Heth gordae Anadenobolus putealis Mexico KY857879.1 KY857880.1 [ 3 ] Heth sp. 1 HMM2018 Anadenobolus putealis Mexico KY857881.1 KY857882.1 [ 3 ] Heth sp.…”

“…Several recent studies have provided some nuclear and mitochondrial (mt) DNA sequence data [i.e. the small subunit ribosomal DNA (18S), the large subunit ribosomal DNA (28S) and the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene or the mitochondrial genome] that can be used for species identification or phylogeny of Rhigonematomorpha [6,[14][15][16][17][18][19]. However, the current genetic database for these nematodes remains very limited.…”

The evolution of entomopathogeny in nematodes

“…The parasitic nematodes of insects can leap considerable distances to infect them, in some cases using the host's static electricity to propel themselves. The nematodes associated with millipedes feature spines of varying shapes and sizes that enable them to anchor onto their hosts' intestines (Phillips et al., 2020 ). Even different species of nematodes can collaborate to successfully infect millipedes (Nagae et al., 2021 ), and the level of cooperation can be even more extreme, as seen with nematodes associated with members of different domains, such as bacteria, to kill their host (Stock, 2015 ).…”

“…The parasitic nematodes of insects can leap considerable distances to infect them, in some cases using the host's static electricity to propel themselves. The nematodes associated with millipedes feature spines of varying shapes and sizes that enable them to anchor onto their hosts' intestines (Phillips et al, 2020). Even different species of nematodes can collaborate to successfully infect millipedes…”