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.

Nematodes associated with palm and sugarcane weevils in South Florida with a description of Acrostichus floridensis n. sp

During a 2016 survey of the nematode associates of the native palmetto weevil,Rhynchophorus cruentatus, and the recently introduced West Indian sugarcane weevil,Metamasius hemipterus(Coleoptera: Curculionidae), from southern Florida, a new species ofAcrostichuswas cultured from a single dissectedR. cruentatusfrom Fort Pierce, FL, USA. Morphological and molecular studies showed that it was new to science and it is described herein asA. floridensisn. sp. The new species is characterised by its male tail characters, spicule morphology with rounded manubrium separated from other parts by clear constriction, smoothly ventrally curved blade, slightly dorsally recurved and pointed tip, more or less straight gubernaculum with widely rounded anterior end and a triangular (arrowhead-like) appendage at the distal tip, and the arrangement of male genital papillae, ⟨(v1, v2), v3 / v4, ad, ph, (v5, v6, v7, pd)⟩. In addition toA. floridensisn. sp. and the previously described nematode associates ofR. cruentatus,i.e.,A. rhynchophori,Teratorhabditis palmarumandMononchoidessp., we recovered a putative new species ofDemaniellaand a new association record withRhabditidoides humicolusandDiplogastrellus metamasiusin Homestead, FL. Dissections and subsequent culturing attempts withM. hemipterusrevealed the previously described nematode associates ofCaenorhabditis angariaandD. metamasiusas well as a new association withR. humicolusin Homestead, FL, USA.

Rhabditidoides aegus n. sp., an associate of stag beetles and sap flow in Japan

Rhabditidoides aegus n. sp. from a stag beetle, Aegus subnitidus subnitidus, from Nagoya, Japan, and obtained from the sap flow of an oak tree, Quercus serrata, from Ibaraki, Japan, is described and illustrated. In addition to its distinguishing generic characteristics, e.g., the arrangement of male genital papillae, ⟨v1, v2, v3d, CO, v4, (ph, ad, v5, v6), pd, v7⟩, the new species is characterised by a relatively stout body for both male and female, small stomatal flaps, a secretory pore-like opening, a pair of deirids, three pairs of postdeirids, and a pair of small subventral vulval papillae located just anterior to the female vulva. The new species is morphologically similar to R. humicolus, the species sharing two typological characters: a stomatal flap and vulval papillae. However, the new species is distinguished from R. humicolus by its relatively small vulval papillae, narrower gubernaculum, and the arrangement of genital papillae in which pd and v7 are clearly separate. In addition to the typological characters, the new species is distinguishable from all other species in the genus by its distribution range as it is the first Rhabditidoides species from East Asia.

Diplogasteroides nix n. sp. (Nematoda: Diplogastridae), a cryptic species related to D. andrassyi, isolated from Monochamus urussovii (Coleoptera: Cerambycidae) from Hokkaido, Japan, with remarks on body surface structures

Diplogasteroides nix n. sp. is described based on its typological characteristics, molecular profile and mating experiments. Diplogasteroides nix n. sp. is characterised by its tube-like stoma with three small dorsal teeth and two subventral ridges, spicule clearly ventrally bent at one-third from the anterior end, gubernaculum with a somewhat squared anterior end and sharply pointed distal end in a lateral view and nine pairs of genital papillae with an arrangement of ⟨v1, (v2, v3d)/v4, ad, ph, (v5, v6, v7), pd⟩, with the very small v5 and v6 protruding from socket-like bases, and v6 has a tripartite tip on males and well developed receptaculum seminis in females. In addition to the general morphological characters, the new species has several small secretory pore-like openings connected to secretory cells just beneath the surface cuticle (tentatively termed as ‘lateral glands’) in both males and females, and two pairs of button-like surface structures with clear internal connections in females. The new species is typologically and molecularly very similar to its tentatively assigned closest relative, D. andrassyi. These two species are morphologically almost identical, forming a cryptic species complex with some very minor morphological differences, e.g., the morphology of gubernaculum somewhat roundish squared vs clearly rounded anterior edge. Molecularly, these two species have identical small subunit sequences and have only 5 bp difference in the D2-D3 extension segments of the large subunit. However, the new species can be distinguished from D. andrassyi by mating incompatibility, yielding only F1 progenies in both male × female and female × male combinations. Biologically, these two species and another close relative were isolated from different carrier Monochamus longhorn beetles, i.e., D. nix n. sp., D. andrassyi and D. asiaticus have been found from M. urussovii, M. grandis and M. alternatus, respectively. However, because these beetle species share the distribution range and host tree species, further collection and identification are necessary to understand their host (carrier) interactions and specificity.

Allodiplogaster josephi n. sp. and A. seani n. sp. (Nematoda: Diplogastridae), associates of soil-dwelling bees in the eastern USA

Two commensal associates of bees,Allodiplogaster josephin. sp. from the Dufour’s gland of a cellophane bee (Colletes thoracicus) from Maryland, USA, andA. seanin. sp. from the abdominal glands of an andrenid bee (Andrena alleghaniensis) from New York, USA, are described and illustrated. Both species were collected as dauers from their respective hosts and cultured on bacteria on tryptic soy broth (TSB) or NGM agar.Allodiplogaster josephin. sp. andA. seanin. sp. are morphologically closer to each other than to other species ofAllodiplogaster, which was recently revised to include 37 valid species. However, the two new species are distinguished by reproductive isolation, shape of the spicule manubrium, host associations and molecular characters, the latter in sequences of the near-full length small subunit (SSU) rRNA gene, D2-D3 expansion segments of the large subunit (LSU) rRNA gene and partial mitochondrial COI. Morphological characterisation was supplemented by scanning electron microscopy (SEM), which revealed furcation of both v5 and v6 male genital papillae, consistent with previous reports for species of thehenrichaegroup ofAllodiplogaster.