Ultrastructure and life history of Myolaimus byersi n. sp. (Myolaimina: Myolaimidae), a phoretic associate of the crane fly, Limonia schwarzi (Alexander) (Limoniidae), in Florida

Abstract

Myolaimus byersi n. sp., a phoretic associate of the crane fly, Limonia (Rhipidia) schwarzi (Diptera: Limoniidae), was recovered from moist and decaying tissue from the crown shaft of a living spindle palm, Hyophorbe verschaffeltii, in southern Florida and is described herein. Dauers were carried in the abdominal folds of male and female L. schwarzi. Examination of the highly mobile crane fly larvae and pupae confirmed that the dauers were externally associated with the cuticle. Dauers from crane flies were culturable to adults on 1/20 strength TSB agar. The association appears to be relatively host specific. SEM studies, early embryonic development, dauers, molecular data and TEM ultrastructural comparisons of the stoma, sensory structures and sperm are used to discuss the relative placement of Myolaimus within the Nematoda. The stoma resembles diplogastrids in being strongly anisomorphic with an enlarged dorsal sector of the stegostom, yet also resembles rhabditids in having three triangular flaps in the metastegostom and matches cephalobs and panagrolaims in having a pharyngeal collar with two sets of three interradial muscles followed by two sets of six adradial muscles. The ultrastructure of the cheilostom epidermis shows a high degree of conservation with several Rhabditida. The sperm of M. byersi n. sp. is nearly identical to that of Caenorhabditis elegans. In early cell division, M. byersi n. sp. is closest to Parascaris equorum followed by C. elegans. Myolaimus apparently represents a divergent lineage that has followed a non-coalescing trajectory for a long time, allowing it to retain some highly conserved characters while also developing some surprisingly unique features, such as a baggy cuticle and males that lack a gubernaculum or spicules. Giblin-Davis, 1997). Myolaimus is very interesting because it is the only known free-living nematode that has evolved a unique mating strategy involving the loss of its gubernaculum and spicules (Fürst von Lieven et al., 2005), the copulatory structures used by almost all other male nematodes to anchor and mate with females. In addition, members of the genus possess a uniquely baggy cuticle that drapes loosely around © Koninklijke Brill NV, Leiden, 2010 M. heterurus in

Reconstruction of the pharyngeal corpus of Aphelenchus avenae (Nematoda: Tylenchomorpha), with implications for phylogenetic congruence

“…, 1998) and Panagrolaimorpha (De Ley et al. , 1995) and in the possibly more distant outgroup Myolaimus byersi (Giblin‐Davis et al. , 2010).…”

“…, 1995), the diplogasterid Aduncospiculum halicti (Baldwin et al. , 1997), C. elegans (Wright & Thomson, 1981), and the possibly more distant outgroup Myolaimus byersi (Giblin‐Davis et al. , 2010).…”

“…, 1997; Dolinski et al. , 1998; Dolinski & Baldwin, 2003; Giblin‐Davis et al. , 2010) and cells of the pharyngeal postcorpus (Zhang & Baldwin, 1999, 2000, 2001; Baldwin, Souza & Dolinski, 2001).…”

Structure, development, and evolutive patterns of spermatozoa in rhabditid nematodes (Nematoda: Rhabditida)

“…The pie charts along the branches illustrate the probabilities for the ancestral states reconstructed in BayesTraits. The observed character state of each taxon is indicated with circles before the taxon names morphology of spermatozoa has also proved to be useful (Bird & Bird, 1991;Giblin-Davis et al, 2010;van Waerebeke et al, 1990;Yushin, Yoshida, & Spiridonov, 2007). We hypothesized that the spermatogenesis comprises, as well as the conserved "rhabditid" pattern, rapidly evolving specific traits that are phylogenetically informative.…”

Rhabditidoides humicolus n. sp. associated with arthropods from rotting palm tissue in Florida, USA

“…(spindle palm) revealed a variety of free-living nematodes, including Myolaimus byersi Giblin-Davis, Kanzaki & De Ley, 2010(Giblin-Davis et al, 2010, and an undescribed Rhabditidoides sp. which was associated as dauers with many of the arthropods therein.…”