A morphometric analysis of the genus Terschellingia (Nematoda: Linhomoeidae) with redefinition of the genus and key to the species

Abstract

The cosmopolitan and often ecologically dominant genus Terschellingia (Nematoda: Linhomoeidae), with 38 nominal species, is taxonomically a problematic taxon. Its species show high morphological plasticity, possess few diagnostic characters and identification keys are lacking. A revision of the genus was carried out based on morphological and morphometric data from the literature and from observations of specimens collected in Cienfuegos Bay, Caribbean Sea, Cuba. The diagnosis of the genus Terschellingia is emended. Of the current 38 nominal species, 15 are considered as valid species based on morphological characters related to size and position of amphidial fovea, presence/position of cephalic and cervical setae, presence/size/shape of pharyngeal bulb, shape of spicular apparatus and shape of tail. Tabular and pictorial keys were provided based on these characters. Three sympatric species: T. communis, T. gourbaultae and T. longicaudata were redescribed based on recently collected Cuban specimens. Each of them showed relatively large differences in body size in comparison with the respective type specimens, suggesting possible variation due to local environmental differences. The highest intraspecific variation pertains for the most widely spread cosmopolitan species T. longicaudata, suggesting that morphological plasticity enhanced adaptation to different environmental conditions. The notable taxonomic inflation within the genus (14 species inquirendae, 9 junior synonyms), probably also present in other highly specious genera of marine nematodes, can lead to an overestimation of the alpha-diversity.

Lack of population genetic structure in the marine nematodes Ptycholaimellus pandispiculatus and Terschellingia longicaudata in beaches of the Persian Gulf, Iran

“…trachygaster complex (De Oliveira et al., ). Given the paucity of diagnostic characters and the high morphological plasticity of most species of Terschellingia (Armenteros et al., ), an integrative approach to the taxonomy of this genus, combining multilocus molecular and dedicated morphological tools, is warranted.…”

“…They were rinsed three times with sterile distilled water to remove DESS. Each specimen was mounted individually on a temporary slide and identified using diagnostic morphological characters (Armenteros, Ruiz‐Abierno, Vincx, & Decraemer, ) under a LEICA DM R research microscope at high magnification. Diagnostic features of P. pandispiculatus and Te.…”

Three new species of Microlaimus (Nematoda: Microlaimidae) from the South Atlantic

“…The percentage occupied by the amphidial fovea was previously indicated as an interspecific morphological variation for Microlaimus by Armenteros, Vincx & Decraemer (2010) . Furthermore, Armenteros et al (2009) argued that morphometry could be used in studies of phylogenetic relationships. These authors also suggested the possibility of evaluating the relationship between morphological plasticity and ecological success in free-living marine nematodes, based on a model proposed by Hollander (2008) .…”

Guitartia tridentata n. gen., n. sp. (Monhysterida: Xyalidae) and Macrodontium gaspari n. gen., n. sp. (Chromadorida: Microlaimidae), free-living marine nematodes from the Caribbean Sea

“…We detected relatively few species of nematodes (79) in Cienfuegos Bay, most of them belonging to the order Monhysterida due to the dominance of fine, muddy, sediments in the basin. Two genera of freeliving marine nematodes from this bay have been reported as new for science (Cienfuegia Armenteros, Vincx &Decraemer, 2009 andPseudoterschellingia Armenteros, Vincx &Decraemer, 2009). In this article we present the description of two new genera belonging to the families Xyalidae Chitwood, 1951 andMicrolaimidae Micoletzky, 1922a.…”