A new species of Litomosoides Chandler, 1931 (Nematoda: Filarioidea) from the long-nosed hocicudo Oxymycterus nasutus Waterhouse (Rodentia: Cricetidae) in Uruguay

Abstract

A new species of Litomosoides Chandler, 1931 was collected from the abdominal cavity of Oxymycterus nasutus Waterhouse (Rodentia: Cricetidae) in the grassland of the Departamento Rocha, Uruguay. Litomosoides nasuti n. sp. belongs to the 'sigmodontis group', and is characterised by: salient amphids; two ventral and one dorsal labial papillae, but no cephalic papillae; a buccal capsule with a transparent anterior segment and an annular asymmetrical thickening; a muscular oesophagus; a bottle-shaped buccal cavity; the male with symmetrically situated cloacal papillae (one pair ad-cloacal and three pairs post-cloacal); phasmids displaced laterally to the longitudinal axis; and microfilariae without terminal nuclei in the tail tip. It resembles five known species; three of which have been recovered from Oxymycterus spp. in neighbouring countries. However, the new species can be differentiated from L. sigmodontis Chandler, 1931 by the shape and size of the buccal capsule; from L. navonae Notarnicola, 2005 by the muscular oesophagus; from L. legerae Bain, Petit & Berteaux, 1980 by the length of the oesophagus and the cephalic papillae; from L. anguyai Notarnicola, Bain & Navone, 2002 by the absence of lappets in the female tail; and from L. oxymycteri Notarnicola, Bain & Navone, 2000 by absence of pre-cloacal papillae. L. legerae from O. quaestor and L. sigmodontis from Sigmodon hispidus in North America are closely related species, as indicated by Brant & Gardner's phylogenetic tree based on morphological characters. However, a new analysis is needed to include the recently described Argentinean species for a better understanding of the diversification of this genus.

Description of Litomosoides ysoguazu n. sp. (Nematoda, Onchocercidae), a parasite of the tuft-toed rice rat Sooretamys angouya (Fischer) (Rodentia: Cricetidae), and a first record of L. esslingeri Bain, Petit & Berteaux, 1989 in Paraguay

“…Notarnicola, 2005 (44.8-72.3 mm); L. taylori Guerrero & Bain, 2011 (mean 54.3 mm); and L. circularis (von Linstow, 1899) (65 mm). Moreover, the new species can be differentiated from L. patersoni in having a buccal capsule with a thickening instead of irregular walls, and by the slender microfilaria instead of a stout one (Notarnicola et al, 2010); from L. oxymycteri by the absence of a precloacal papilla (Notarnicola et al, 2000); from L. anguyai and L. nasuti in having no salient amphids and a complete set of head papillae (Notarnicola et al, 2002;Notarnicola & Navone, 2009); from L. navonae in having a more posteriorly located vulva (mean 2,023 vs 1,359 lm from the anterior extremity) and microfilaria with a sheath visible only at the anterior extremity (Notarnicola, 2005); from L. taylori by the presence of a thickening in the buccal capsule instead of irregular walls ; and from L. circularis by a shorter right spicule (mean length 80-110 vs 98-121 lm) and different spicular ratio (mean 3.5 vs 2.8) .…”

Study of types of some species of “Filaria” (Nematoda) parasites of small mammals described by von Linstow and Molin

“…The morphological features that distinguish L. circularis from the 17 other species of the sigmodontis group subsequently described are listed in the following discussions (Mazza, 1928; Caballero, 1939 & 1947; Esslinger, 1973; Muller, 1980; Bain et al , 1980 & 1989; Brant & Gardner, 1997; Notarnicola et al , 2000 & 2002; Guerrero et al , 2002; Bain et al , 2003; Notarnicola, 2005; Notarnicola & Navone, 2009; Notarnicola et al , 2010).…”

“…L. patersoni (Mazza, 1928) redescribed by Notarnicola et al (2010), has shorter, stout microfilariae (34-44), a pair of precloacal papillae, complete set of head papillae, and straight female tail with pointed extremity. Five species have prominent amphids; three of these have microfilariae longer than 75 (62-63 long in L. circularis ): in L. anguyai Notarnicola, Bain & Navone, 2002 the male has a pair of precloacal papillae; L. legerae Bain, Petit & Berteaux, 1980 has a complete set of head papillae, a buccal capsule with thick irregular walls and microfilaria with a caudal filament; in L. oxymycteri Notarnicola, Bain & Navone, 2000 the fourth pair of caudal papillae is joined on the median ventral line; L. nasuti Notarnicola & Navone, 2009 has no apparent cephalic papillae, a buccal capsule with conspicuous ring at mid-length and phasmidial knobs; L. navonae Notarnicola, 2005 has six or seven pairs of caudal papillae. Three species have a buccal capsule with a symmetrical annular thickening with its posterior rim oriented backwards and some other distinctive characters: in L. galizai Bain, Petit & Diagne, 1989 the buccal capsule is thinner in both sexes and longer in the male, 25-30 (14-16 in L. circularis ); in L. khonae Bain, Petit & Diagne, 1989 the female tail is curved dorsally and in both sexes the tail tip is acute; in L. chagasfilhoi Moraes Neto, Lanfredi & de Souza, 1997 the oesophagus is undivided and the left spicule has a long membranous terminal sheath.…”

Litomosoides pardinasi n. sp. (Nematoda, Onchocercidae) from two species of cricetid rodents in northern Patagonia, Argentina

“…More than 30 species of Litomosoides Chandler 1931 were reported in the American continent from different groups of hosts, such as bats of the families Phyllostomidae and Vespertilionidae, marsupials Didelphidae, and rodents of the families Ctenomyidae, Echimyidae, Sciuridae, and Cricetidae (Bain et al 1989;Brant and Gardner 1997;Esslinger 1973;Guerrero et al 2002;Notarnicola and Navone 2009;Notarnicola et al 2010a). In the last 10 years, five new species of Litomosoides were described in cricetid rodents in central and northeastern Argentina, and L. patersoni (Mazza 1928) was found in the type host and type locality in the northwest of the country and has been redescribed (Notarnicola 2005;Notarnicola et al 2000Notarnicola et al , 2010b.…”