Sprattia spearei, 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 : 51-53

Sprattia spearei sp. nov.

( Figs. 90–98 )

Type host. Isoodon macrourus (Marsupialia: Peramelidae ).

Site in host. Lungs (probably blood vessels).

Material examined. Holotype ♂, incomplete, anterior and posterior ends, from lungs Isoodon macrourus, Douglas, Townsville , Queensland (19 0 15’S, 146 0 49’E), coll: R. Speare, 1.iv.1979, AHC 45888, allotype ♀, incomplete, anterior and posterior ends AHC 45889; paratype: ♂ posterior end, QM G232537. L 4 ♂, N1042.

Etymology. The species is named after my long–time colleague Dr. Richard Speare, whose long experience working with species of Strongyloides no doubt played a role in his finding and collecting these minute nematodes. Differential diagnosis. Sprattia spearei from the northern brown bandicoot, Isoodon macrourus , is distinguished from both S. capilliformis from the little northern quoll, Dasyurus hallucatus , and S. caninus from the short–eared brushtail possum, Trichosurus caninus , by the minute size of adults, smaller spicules, absence of transverse bands of refractile cuticular bosses and smaller number and arrangement of cloacal papillae.

Description. General: Minute nematodes with sharply tapered anterior and posterior extremities. Oral opening relatively large, laterally elongated. Four pairs of submedian papillae arranged in outer circle of four small papillae and inner circle of four smaller papillae. Inconspicuous cuticular peribuccal fields present, more apparent dorsally and ventrally than laterally, joining bases of inner and outer circles of papillae, dorso–ventrally elongated. Internolateral papillae conspicuous even in whole mount. Amphids lateral, small, opening posterior to papillae of outer circle. Buccal capsule large, dorso–ventrally elongated, with thickened cuticular walls, without. refractile ring at its base.. Oesophagus short, not divided into anterior muscular and posterior glandular regions. Intestine broad, thick walled. Excretory pore observed only in male. Cuticle with fine, transverse annulations, most apparent in caudal region of male anterior to cloaca, transverse bands of refractile, cuticular bosses absent. Spicules unequal, dissimilar. Gubernaculum absent. Minute lateral caudal alae suspected. Phasmids and deirids not observed.

Male (Holotype in italics): BL unknown. MW 55, 55 in mid–body region. NR 155, 155. EP 210, 222. O 485, 488. Posterior end not coiled helically. LS 196, 195, Cal 86, 85; Lam 34, 32; Fil 79, 77. RS 64, 63 with fine needle– like distal extremity with membranous sheath. Gubernaculum absent. Cloacal papillae six in number, clustered around cloacal aperture, one large, pedunculate pair immediately pre–cloacal, one small pair immediately post–cloacal and one medium sized pair posterior to them. T 90, 78, terminating in two small, latero–ventral papillae.

Female (Allotype in italics) BL unknown. MW 91. NR 92. EP not observed. O undetermined length. V 300. T 105, caudal papillae not observed.

Microfilaria: Unknown.

Fourth–stage larva: BL 2.54 mm. MW 27. Prominent, elongate, buccal capsule 8 long. NR 92. Paired excretory cells with conspicuous nuclei 177 from cephalic end. O 260 long. Developing primordia of spicule pouches observed. T 60, terminating in rounded end with pair of phasmids.

Distribution and host. Sprattia spearei is known only from a single Isoodon macrourus from the campus of James Cook University, Townsville, Queensland although numerous bandicoots have been examined from this and other northern and southern locations in Queensland in the past half century or more.

Remarks. Sprattia spearei from the northern brown bandicoot is probably the smallest filarioid species known from Australasian marsupials and murid rodents. It is distinguished from S. capilliformis from the little northern quoll and S. venacavincola from the short–eared possum as noted under the differential diagnosis provided. In all probability, given its exceptionally narrow width, it inhabits blood vessels like its two conspecifics. Although microfilariae were not observed in the vagina or uterus of the female, those of the other two species are sheathed and occur in the blood of the hosts. Those microfilariae, the microfilaria of Pelecitus roemeri from kangaroos and wallabies, that of Monanema australe from the fawn-footed melomys and the naked tailed rat and that from Mesembriomys gouldii reported in Mackerras (1962) are the only sheathed microfilariae known to date from Australasian monotremes, marsupials and murids.

Figures

FIGURES 90–98. Sprattia spearei sp. nov. 90, Cephalic end, apical view. 91, Cephalic end, lateral view. 92, Anterior end female, lateral view. 93, Caudal end, male, showing fine cloacal alae, one pair of pedunculate papillae and papillae clustered around cloacal opening, ventrolateral view. 94, Caudal end female, lateral view. 95, Caudal end male, lateral view. 96, Left spicule, lateral view. 97, Right spicule, lateral view. 98, Vulva and vagina uterina, female, lateral view. Scale bars: Figs 90, 91 = 20 µm. Figs 92–98 = 50 µm.