Two new meiofaunal species of Trilobodrilus (Dinophilidae, Annelida) from California, USA

Alexandra Kerbl,Emilie Hernes Vereide,Greg W. Rouse,Brett C. Gonzalez,Katrine Worsaae

doi:10.5852/ejt.2018.421

Alexandra Kerbl, Emilie Hernes Vereide + Show 3 more

Open Access

https://doi.org/10.5852/ejt.2018.421

Copy DOI

Abstract

We describe two new species of the annelid genus Trilobodrilus Remane, 1925 (Dinophilidae Verill, 1892) from an intertidal and a subtidal location in San Diego, California. These two species show morphological and molecular divergences between each other and the previously described, geographically distant species. Intertidal T. windansea sp. nov. differs from subtidal T. ellenscrippsae sp. nov. most remarkably in the number and pattern of ciliary tufts and bands on the prostomium and along the body length, besides showing ca 15% difference in gene fragments of COI and CytB. Trilobodrilus windansea sp. nov., though nesting with T. ellenscrippsae sp. nov. in the molecular phylogenetic analyses, morphologically resembles the Japanese T. itoi Kajihara, Ikoma, Yamasaki & Hiruta, 2015 most closely, but still differs from this species in the higher number of apical ciliary tufts, an additional ciliary row posterior to the second ciliary band, and by lacking a forth ciliary band and segmentally arranged lateral ciliary tufts. Trilobodrilus ellenscrippsae sp. nov. is morphologically most similar to the Japanese T. nipponicus Uchida & Okuda, 1943, but is much shorter, has more apical ciliary tufts, and less regularly arranged lateral ciliary tufts along the body. All species differ significantly in all compared gene fragments, and no obvious correlation was found between habitat and the species morphology or relationships.

Highlights

IntroductionThe entirely meiofaunal annelid family Dinophilidae Verill, 1892 consists of 16 accepted species (Westheide 2008; WoRMS Editorial Board 2016) classified into two genera, Dinophilus O.Schmidt, 1848
The entirely meiofaunal annelid family Dinophilidae Verill, 1892 consists of 16 accepted species (Westheide 2008; WoRMS Editorial Board 2016) classified into two genera, Dinophilus O.Schmidt, 1848(10 species) and Trilobodrilus Remane, 1925 (6 species)
The prostomium of the species of Trilobodrilus lacks eyes and appears swollen in the posterior part followed by a constriction at the border of the first segment, giving it a trilobed appearance compared to the rounded prostomium of Dinophilus species (Remane 1925; Westheide 1967, 2008)

Summary

Introduction

The entirely meiofaunal annelid family Dinophilidae Verill, 1892 consists of 16 accepted species (Westheide 2008; WoRMS Editorial Board 2016) classified into two genera, Dinophilus O.Schmidt, 1848. Compared to Dinophilus, Trilobodrilus lacks dorsal transverse ciliary bands except for one to two complete or incomplete bands on the first segment (Remane 1925; Uchida & Okuda 1943; Westheide 1967, 2008; Rao 1973; Kajihara et al 2015). Similar to species of Dinophilus, species of Trilobodrilus are generally gonochoric (Remane 1925; Uchida & Okuda 1943; Westheide 1967; Ax 1968; Rao 1973; Kajihara et al.2015), except for T. hermaphroditus Riser, 1999, which is hermaphroditic (Riser 1999). The here presented study describes two species of Trilobodrilus from coastal southern California, based on light and electron microscopic examinations as well as on molecular sequencing and a phylogenetic analysis of the genus

Material and methods

Results

Discussion