Breinlia (Breinlia) melomyos, Spratt, 2011

Spratt, David M., 2011, New records of filarioid nematodes (Nematoda: Filarioidea) parasitic in Australasian monotremes, marsupials and murids, with descriptions of nine new species 2860, Zootaxa 2860 (1), pp. 1-61 : 17-19

Breinlia (Breinlia) melomyos , sp. nov.

( Figs 29–37 )

Synonyms: Breinlia pseudocheiri Spratt & Varughese, 1975 sensu Smales (2005) ; Breinlia thylogali Mackerras,1954 sensu Smales (2005) .

Type host. Melomys sp. cf burtoni (Ramsay) (Eutheria: Muridae ).

Site in host. Peritoneal and pleural cavities.

Material examined. Holotype: ♂, from Melomys sp. cf burtoni, Mitchell Plateau , Western Australia, coll: P.J.A. Presidente, 22.iv.1982, AHC 45852; allotype: ♀, collected 19.iv.1982, AHC 45853; paratypes: 2♂, 1♀, AHC 45854.

Other material examined. From M. sp. cf burtoni WA : 2♂, 3♀, QM G232516; 1♀, from pleural cavity, ( N2744 ) ; 1♀, ( N2750 ) , 1♀, ( N2752 ) , 1♀, ( N1854 ) , 2♂, 11♀, ( AHC 45855) , Mitchell Plateau.

Etymology. The species is named after the host genus.

Differential diagnosis. Breinlia (B.) melomyos from a grassland melomys from the Mitchell Plateau of Western Australia is morphologically most similar to B. (B.) sergenti from the slow lemur in Calcutta, B. (B.) beveridgei from whiptail wallabies in north Queensland and B. (B.) zyzomyos from rock–rats also in the Mitchell Plateau region. Breinlia (B.) melomyos is distinguished from Breinlia (B.) sergenti by slighty longer left and shorter right spicules resulting in a spicule ratio of 1:2.75 rather than 1:2.20, shorter calomus, lamina and much longer filament of left spicule, the distribution of pre– and post–cloacal papillae with B. (B.) melomyos having 4 pairs rather than 3 pairs pre–cloacal and without a subterminal pair, generally more anterior position of the vulva and much shorter tail in females. It is distinguished from B. (B.) beveridgei by generally longer males, the absence of large ear–like cephalic papillae of the outer circle, shorter glandular oesophagus, slightly shorter left and right spicules, broader gubernaculum which does not appear to surround the distal tip of the right spicule and more dense and broadly distributed longitudinal refractile cuticular bosses in males It is distinguished from B. (B.) zyzomyos by shorter males and females, presence of a cuticular peribuccal field in apical view, shorter left and particularly right spicules, shorter glandular oesophagus and tail in males and females terminating with two pairs of latero–ventral papillae rather than a single subterminal pair and a larger median terminal one in males, and more anterior position of the vulva.

Description. General: Moderately long nematodes with attenuated extremities. Oral opening small, rounded. Four pairs of submedian papillae arranged in outer circle of four large papillae and inner circle of four slightly smaller papillae. Oval, cuticular peribuccal field present, formed by elevation of cuticle joining distal extremities of papillae of inner circle. Second field joining distal extremities of papillae of outer circle not present. Pair of internolateral papillae located anterior to amphids at level of inner circle of papillae. Amphids lateral, moderate size, opening at level of outer circle of papillae. Buccal capsule minute, narrow with conspicuous, refractile, ring at its base. Oesophagus divided into short anterior muscular and long posterior glandular regions, variable in lengths, particularly the latter. Intestine broad. Excretory pore distinct in some male and female specimens, not observed in others. Cuticle with fine, transverse annulations, refractile bosses present only on posterior ventral and portion of lateral surfaces of males. Lateral cords with 3 columns of nuclei, a narrow, central column of widely–spaced, elliptical nuclei with prominent nucleoli and wider, peripheral columns of closely–spaced, elliptical nuclei with prominent nucleoli. Spicules unequal, dissimilar. Gubernaculum present. Lateral alae absent. Phasmids observed in males only.

Male: (holotype measurements presented first in italics, followed by 4 paratypes). BL 42, 41(39–43) mm. MW 265, 259 (212–292) in mid–body. NR 212, 208 (185–228). EP 391, 384. MO 364, 367 (345–398). GO 875, 868 (848–928). Posterior end coiled helically. LS 354, 344 (328–357); Cal 165, 159 (152–166), Lam 73, 68 (62–76), Fil 135, 115 (114–135), surrounded by fine membranous sheath. RS 118, 129 (118–135), with spatulate distal extremity. Gub 30, 29 (25–31). Cloacal papillae 13–14 in number, generally four pairs pre– and three pairs post– cloacal or two pairs and a single median post–cloacal papilla. One pair large subterminal papillae 13 µm from tail tip in one specimen. T 427, 432 (391–450), terminating in pair of small, latero-ventral papillae.

Female: (allotype measurements presented first in italics, followed by 8 paratypes). BL 85, 58(32–75). MW 477, 368 (212–530). NR, 208 195 (183–232). EP not observed on allotype, 364(342–386). MO 186, 318 (265– 371). GO 1272, 845 (700–901). V 3950, 2133 (1568–3002). T 610, 503 (450–731), terminating in pair of small, latero-ventral papillae.

Microfilariae: Unknown.

Distribution and hosts. Breinlia (B.) melomyos is known only from the grassland melomys, Melomys sp. cf. burtoni from the Mitchell Plateau region of northern Western Australia. Melomys burtoni (Ramsay) is distributed along the east coast of Australia from northern New South Wales to Cape York Penninsula and across the north from Cobourg Peninsula, Northern Territory into the Kimberley Region of Western Australia. The Northern Territory population has a continuous distribution with the Western Australia population in monsoon forests and vine thickets, riparian woodlands and mangroves. It has been identified as M. burtoni on the basis of molar patterns and chromosomal and electrophoretic studies ( Begg et al., 1983), despite disjunction from the eastern population. However, there remains some doubt as to species identity of the Kimberley population and it is here referred to as Melomys sp. cf. burtoni following Kerle (1995). Filarioids have not been reported from Melomys burtoni in the Northern Territory, Queensland and New South Wales ( Smales 2005) nor from its congener M. cervinipes (Gould) in northern and eastern Australia ( Smales et al. 2004). Similarly, there are no records of filarioids from species of Melomys from PNG ( Jones & Anderson 1990, 1996; Smales 2005, 2009)

Remarks. Breinlia (Breinlia) melomyos is most similar to B. (B.) zyzomyos from rock–rats in the same geographical area, B. (B.) beveridgei from whiptail wallabies in north Queensland and B. (B.) sergenti from the slow lemur in Calcutta, and distinguished from them under the differential diagnosis provided. Among other known Australian species, it is most similar to B. (B.) pseudocheiri from the peritoneal cavity of the western ringtail possum, Pseudocheirus occidentalis (Thomas, 1888) , in southern Western Australia and the common ringtail possum, P. peregrinus (Boddaert, 1785) in southeastern Australia. It is distinguished from this species by the shorter lengths of males and females, the oval rather than quadrilateral peribuccal field joining the bases of the inner circle of papillae, slightly shorter right spicule, greater number and distribution of cloacal papillae, shorter tail terminating in a pair of latero-ventral papillae rather than a subterminal papilla and three terminal papillae in the male, shorter muscular pharynx and more anterior position of the vulva in females.

The report by Smales (2005) of B. pseudocheiri and B. thylogale from this host on the Mitchell Plateau in the Kimberleys, pertain to the currently described species. The genus Melomys is a member of the “new endemic” Australasian subfamily Hydromyinae , tribe Uromyini which has a long evolutionary history in New Guinea. It, along with the genera Uromys and Pogonomys , are shared with New Guinea and thought to have travelled to Australia across woodland and savanna land bridges during the Pleistocene, approximately 40,000 years ago ( Flannery 1995; Godthelp 2001).

A number of species of Breinlia (Breinlia) have been described from small mammals in India ( Petter 1958; Chowattukunnel & Esslinger 1979), southeast Asia ( Singh & Ho 1973; Bain et al. 1979, 1981) and Indonesia (Punomo & Bangs 1996), including two species from murid rodents, B. (B.) booliati and B. (B.) tinjili belonging to the cosmopolitan genus Rattus . Breinlia (Breinlia) melomyos is the first species of the subgenus described from rodents in Australia. No species of Breinlia is yet known from native species of Rattus in Australia despite a number of parasitological investigations (see Smales 1997).

Figures

FIGURES 29–37. Breinlia (Breinlia) melomyos sp. nov. 29, Cephalic end, apical view. 30, Vulva and vagina, lateral view. 31, Posterior extremity female, lateral view. 32,. Anterior extremity female, lateral view. 33, Caudal end female, lateral view. 34, Posterior end male, lateral view. 35, Right spicule, lateral view. 36, Oesophago-intestinal junction female, lateral view. 37, Cuticular ornamentation and lateral cord, male, 3.2 mm anterior to cloaca. Scale bars: Figs. 29, 37 = 25 µm, Figs. 30–34, 35 = 50 µm, Fig. 36 = 100 µm.