On the identity of Labronema plica Ciobanu, Popovici & Decraemer, 2004 and proposal for its transfer to the genus Thonus Thorne, 1974 (Nematoda: Dorylaimoidea)

Abstract

Nematology , 2008, Vol. 10(4), 599-602 Short communication On the identity of Labronema plica Ciobanu, Popovici & Decraemer, 2004 and proposal for its transfer to the genus Thonus Thorne, 1974 (Nematoda: Dorylaimoidea) Marcel C IOBANU 1 , 2 , ∗ , Iuliana P O P OVI C I 1 , Wilfrida D ECRAEMER 3 , 4 and Reyes P ENA -S ANTIAGO 2 During a revision of a number of species belonging to the genus Thonus Thorne, 1974 and analysis of the rela- tionships of this genus with its relatives, including Cras- solabium Yeates, 1967, Labronema Thorne, 1939 and Takamangai Yeates, 1967 (see Pena-Santiago & Ciobanu, 2007a, b), several species with problematical identity or taxonomy were re-examined to try to establish more ro- bust diagnostic features to separate the taxa concerned. Labronema plica Ciobanu, Popovici & Decraemer, 2004, described from a salt-affected area in Romania, is an in- teresting species as its general morphology also fits the Thonus pattern. Type material (female holotype, one fe- male paratype and the only male paratype) were available to study, as well as one new specimen (a young female), also from the type locality. Their study provided addi- tional data to clarify its identity. Re-examination of Labronema plica type material (Fig. 1) showed that the female had the following mor- phology: lip region offset by marked depression, rela- tively high and cap-like, i.e. , with its inner portion dis- tinctly elevated. Lips largely amalgamated. Cheilostom distinctly widened in posterior half. Guiding ring simple, plicate. One of two anterior ventrosublateral pharyngeal gland nuclei lacking or obscure. Junction between pha- ryngeal base and cardia enveloped by a very shallow, ring- like, structure. Genital tract poorly differentiated: oviduct 110-115 µ m long or 2.4-2.5 corresponding body diam. 1 Institute of Biological Research, Department of Plant and Animal Taxonomy and Ecology, 48 Republicii Str., RO-400015 Cluj-Napoca, Romania 2 Departamento de Biologia Animal, Vegetal y Ecologia, Universidad de Jaen, Campus ‘Las Lagunillas’ s/n, Edificio B3, 23071-Jaen, Spain 3 Royal Belgian Institute of Natural Sciences, Vautierstraat 29, B-1000 Brussels, Belgium 4 University of Ghent (UGent) Department of Biology, Ledeganckstraat 35, B-9000 Ghent, Belgium ∗ Corresponding author, e-mail: icb@cluj.astral.ro Received: 4 December 2007; revised: 16 January 2008 Accepted for publication: 16 January 2008 Keywords: diagnosis, new combination, Romania, taxonomy, Thonus plica n. comb. long, with small, more or less spheroid, pars dilatata ; dis- tinct sphincter marking oviduct-uterus junction; uterus a simple tube 100-115 µ m long or 2.2-2.5 corresponding body diam. Pars proximalis vaginae longer than wide, with slightly sigmoid walls, surrounded by weak mus- culature. Pars refringens vaginae with two separated, tri- angular sclerotised pieces in longitudinal optical section. Pars distalis vaginae short, lacking any differentiation. Vulva pore-like. Two developed gland cells, one anterior, other posterior, present near vagina-vulva junction. Cau- dal pores comprising two subterminal pairs, one lateral, one subdorsal. Male tail straighter ventrally than that of female. This species is characterised by its medium size (L = 1.31-1.38 mm), lip region cap-like and 13.0-13.5 µ m diam., odontostyle 11-12 µ m long with aperture occupy- ing ca two-fifths of total length, guiding ring simple (but plicate), neck 287-312 µ m long, expanded part of pha- rynx 110-127 µ m long or 38-40% of total neck length, pars refringens vaginae with two separated pieces in op- tical section, vulva pore-like and almost equatorial (V = 50-53), presence of pre- and post-advulvar cuticular wrin- kles, presence of gland cells near vagina-vulva junction, tail conoid-rounded (25-26 µ m; c = 52-53; c ′ = 0.7), and male with 16 contiguous precloacal mid-ventral supple- ments and spicules 53 µ m long. © Koninklijke Brill NV, Leiden, 2008 599 Also available online - www.brill.nl/nemy