Anatomical and molecular characterization of some rhigonematid parasites of millipedes in Nigeria, with new insights into their phylogeny.

Parasitic nematodes of millipedes from Nigeria are molecularly characterized for the first time. During nematode surveys on live giant African millipedes from several localities in Nigeria, 4 species of rhigonematids were identified by application of integrative taxonomical approaches (morpho-anatomy and molecular markers), including Brumptaemilius sp., Gilsonema gabonensis, Obainia pachnephorus, and Rhigonema disparovis. The results of morphometric and molecular analyses of D2-D3 28S, ITS, partial 18S rRNA, and cytochrome oxidase c subunit 1 (COI) gene sequences further characterized the rhigonematid species, and clearly separated them from other related species. Phylogenetic relationships based on 28S and 18S rRNA genes suggest that genera within Ransomnematoidea (Ransomnema, Heth, Carnoya, Brumptaemilius, Cattiena, Insulanema, Gilsonema) and Rhigonematoidea (Rhigonema, Obainia, Xystrognathus, Trachyglossoides, Ichthyocephaloides) clustered rather closer than could be expected in view of their morphological differences. Phylogenetic relationships based on ITS and COI are congruent with those of other ribosomal genes; however, they are not conclusive due to the scarcity of available sequences of these genes for these genera in NCBI.

Morphological and molecular characterization of Aporcelinus abeokutaensis sp. n. (Dorylaimida, Aporcelaimidae) from Nigeria.

A new species of dorylaimid nematode, Aporcelinus abeokutaensis sp. n., collected from a watermelon field in Nigeria, is described, illustrated and molecularly (D2-D3 28S ribosomal DNA) studied. It is characterized by its 1.18-1.52-mm-long body, lip region offset by weak constriction, 15.5-17.5 µm broad with perioral liplets, odontostyle 18-21.5 µm long at its dorsal side or 1.1-1.3 times the lip region diameter, neck 333-401 µm long, pharyngeal expansion occupying 45-51% of total neck length, uterus simple and 0.7-1.5 times the corresponding body diameter long, V = 48-53, tail conical with finely rounded tip (33-52 µm long, c = 26-41, c' = 1.3-1.9) and a variably distinct dorsal concavity, and male unknown. Molecular analysis reveals that the new species grouped with other species of Aporcelinus in a highly supported clade, confirming the monophyly of the genus.

Morphological and molecular characterization of Aporcella femina sp. n. (Dorylaimida, Aporcelaimidae) from Nigeria.

A new species of the genus Aporcella collected from a watermelon field in Nigeria is described, including its morphological and molecular (small subunit (SSU) and large subunit (LSU) ribosomal DNA (rDNA)) characterization. Aporcella femina sp. n. is distinguished by its 3.21-3.64 mm-long body, inner cuticle layer with fine but distinct transverse striation, lip region offset by deep constriction, 22-25 µm broad, odontostyle 20-26 µm, neck 661-811 µm long, pharyngeal expansion occupying 52-56% of the total neck length, female genital system didelphic-amphidelphic, uterus 191-350 µm or 1.9-3.3 mid-body diameters long, V = 52-57, tail short and convex conoid (35-48 µm, c = 72-98, c' = 0.7-0.9) and males absent. Phylogenetic analyses based on the partial sequence of SSU and LSU (D2-D3) rDNA revealed a close relationship of A. femina sp. n. with other Aporcella species, confirming the monophyly of the genus as well as its association to a clade made of several taxa characterized by the absence of pars refringens vaginae.