Breinlia (Breinlia) tricondylus, 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 : 35-37

Breinlia (Breinlia) tricondylus sp. nov.

( Figs. 59–68 )

Type host. Macropus rufogriseus banksianus (Marsupialia: Macropodidae ).

Site in host. Peritoneal cavity (connective tissue over dorsal aorta).

Material examined. Holotype: ♂ ( AHC 45875), allotype ♀ ( AHC 45876) from Macropus rufogriseus banksianus, Bondo State Forest , New South Wales (35 0 12’S, 148 0 25’E), coll: D.M. Spratt & P. Haycock, 20.xi.1978.,

Etymology. The species name is derived from the latin, condylus, meaning knuckle or prominence and refers to the three characteristic digitiform, protuberances or knuckles on the distal tip of the right spicule.

Differential diagnosis. The new species is distinguished from all other known species of Breinlia (Breinlia) by having the shortest males and females, possibly the shortest left and the shortest right spicule, and the characteristic morphology of the distal tip of the right spicule with three distinct digitiform protuberances or knuckles. It is further distinguished from the other very short species with short spicules, B. (B.) bigenera , by the morphology of the gubernaculum, not shaped like the top spike of an halberd (or halbert) viewed upside–down, longer muscular and glandular portions of oesophagus, shorter tail of female terminating in two large fleshy papillae one ventral and one dorsal, and the caudal papillae of males not all clustered around the cloacal aperture and with one pair of double ad–cloacal papillae fused throughout.

Description. General: Very short, slender nematodes with attenuated extremities. Oral opening small. Four pairs of submedian papillae arranged in outer circle of four large papillae and inner circle of four small papillae. Cephalic extremity not examined in apical view. Internolateral papillae not observed. Amphids lateral, large, opening at level of outer circle of papillae. Buccal capsule minute, narrow, with delicate wall and small inconspicuous, refractile ring at its base.. Oesophagus divided into short anterior muscular and long posterior glandular regions. Excretory pore distinct. Intestine narrow. Cuticle with conspicuous, transverse annulations. Cuticular bosses not observed. 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 small, unequal, dissimilar, moderately sclerotised. Gubernaculum present. Lateral alae absent. Phasmids and deirids not observed.

Male (holotype): BL 12.7 mm. MW 122 in mid–body region. NR 183. EP 203. MO 284. GO 940. LS 142, Cal 45, Lam 98, Fil absent. RS 68 with spatulate distal extremity and with three conspicuous digitiform processes on distal tip. Caudal papillae 12 in number, single median papilla immediately anterior to cloacal aperture, pair of double ad–cloacal papillae fused throughout, seven post–cloacal papillae arranged as two pairs and three single median papillae. Cuticular inflation projecting over posterior lip of cloacal aperture. Posterior end curved ventrally. T 252, terminating in pair of large, latero–ventral papillae with smaller, slightly elongate, median, sub–terminal pair in tandem on ventral surface.

Female (allotype): BL 18.2 mm. MW 154 in mid–body region. NR 204. EP 251. MO 274. GO 1560. V2070, vagina and uterus extending anterior to vulva but not reaching oesophago–intestinal junction. T 363, terminating in one pair of large papillae, one ventral and one dorsal.

Microfilaria. Unknown.

Distribution and hosts. Breinlia (B.) tricondylus is known only from a male and a female from a single rednecked wallaby collected more than 30 years ago. It has not been seen in this or any other macropodid host since, despite examination of 86 red–necked wallabies in southeastern Australia, including 26 from the type locality.

Remarks. Breinlia (Breinlia) tricondylus is distinguished from all other species in the subgenus as detailed under the differential diagnosis provided. It is the smallest species of Breinlia (Breinlia) known to date with the smallest left (possibly) and right spicules, and in some features is not typical of most other members of the subgenus e.g. the form of the left spicule, especially the junction between calomus and lamina and the apparent absence of a filament, the spatulate distal extremity of the right spicule which terminates in three protuberances, the absence of refractile cuticular bosses, the presence of a single pre–cloacal papilla, the double form of the pair of ad–cloacal papillae, fused throughout and the absence of a conspicuous muscular vulva in the female. The absence of a filament on the left spicule remains problematic as there is only one male specimen and I am not able to determine with confidence if there was a fine filament which has broken off. The differences, especially in the male, are suggestive of a new subspecies. Nevertheless, with only one male and one female specimen found in examination of 86 red–necked wallabies in southeastern Australia in more than 30 years, including 26 from the type locality, and with the presence of other features characteristic of the subgenus Breinlia , I have chosen a conservative position and placed it there. Breinlia (Breinlia) petauristae is somewhat similar insofar as a filament is absent from the left spicule. However, the morphology of the right spicule in that species bears no resemblance to the characteristic form seen in all other species of the subgenus.

Figures

FIGURES 59–68. Breinlia (Breinlia) tricondylus sp. nov. 59, Cephalic end female, lateral view. 60, Anterior end female, lateral view. 61, Vulva, vagina and uterus of female, lateral view. 62, Posterior end female, lateral view. 63, Right spicule and gubernaculum, right lateral view. 64, Left spicule, left lateral view. 65, Posterior end male, lateral view. 66, Caudal end female, lateral view. 67, Caudal end male, lateral view. 68, Cloacal region male, ventral view. Scale bars: Figs 59-61, 63, 64, 66, 67 = 20 µm, Figs 62, 65, 68 = 50 µm.