Progamotaenia onychogale, Beveridge, I. & Shamsi, S., 2009

Beveridge, I. & Shamsi, S., 2009, Revision of the Progamotaenia festiva species complex (Cestoda: Anoplocephalidae) from Australasian marsupials, with the resurrection of P. fellicola (Nybelin, 1917) comb. nov., Zootaxa 1990, pp. 1-29 : 21-23

Progamotaenia onychogale sp. nov.

( Figs 51–58)

Synonyms: Progamotaenia festiva (Rudolphi, 1817) Nybelin, 1917 of Beveridge et al. (1992).

Host: Onychogalea unguifera (Gould) (Marsupialia: Macropodidae ).

Site in host: bile ducts.

Types: Holotype, Springfield Stn via Mt Surprise , Queensland (17° 58’S 144° 26’E), coll. I. Beveridge, 8.xi.1994 ( SAM 28950, AM 495418 ); paratype, same data ( SAM 29334).

Etymology: the name of the new species is derived from the generic name of the host.

Material examined: From O. unguifera : Queensland: types, 45 specimens, Chadshunt Stn via Burketown ( SAM 21375, 21388 , 29335-7 (S), 6633, 6638-40, 6655-6 (W), BMNH 2008.6.3.6-7 (S)), 10 specimens, Wernadinga Stn via Burketown ( SAM 21393, 29338 (S), 6660-3 (W)); fragments, Bylong Stn via Richmond ( SAM 7920 (W)) .

Description: Short, robust worms of variable shape, quadrangular to foliiform, 12–24 (15) long, maximum width 4–10 (8.2) with 54–84 (69) segments in gravid specimens. Scolex large 1.14–1.74 (1.40) in diameter, squat, weakly 4-lobed; suckers circular, 0.406 –0.640 (0.519) in diameter. Neck absent. First mature segment 18–22th (19). Mature segments craspedote, 3.58–8.83 (6.26) wide, 0.08–0.21 (0.16) long. Genital atrium small, slightly posterior to middle of lateral segment margin; cirrus sac elongate, extending well beyond osmoregulatory canals, 0.65–0.1.36 (0.87) long, 0.065 –0.111 (0.093) wide; cirrus unarmed; internal seminal vesicle occupies approx. 2/3–3/4 of volume of cirrus sac, 0.228 –0.867 (0.456) long, 0.065 –0.111 (0.093) wide; elongate external seminal vesicle, covered with glandular cells, 0.130 –0.459 (0.289) long, 0.052 –0.194 (0.089) wide, sometimes overlying cirrus sac; vas deferens coils medially, dorsal to uterus; testes arranged in anterior half of segment between osmoregulatory canals; no space between canals and testis fields; testes arranged in 2–3 dorso-ventral layers, in single band or 2 separate groups; segments with single band or 2 groups occur in same specimen; testes clustered lateral to seminal receptacle, arranged in single file, often sparsely anterior to receptacle, single row or 2 rows medial to receptacle. Testes 0.046 –0.092 (0.063) in diameter; testis number 93–128 (110). Vagina tubiform, lacking glandular investment, opens to genital atrium posterior to cirrus sac, leads to enormous ovoid seminal receptacle 0.224–1.22 (0.696) x 0.078 –0.235 (0.183); seminal receptacle ovoid, greatly elongated, often bilobed, extending from transverse osmoregulatory canal to anterior margin of segment; testes frequently compressed between adjacent receptacles. Ovary small, flabelliform, medial to seminal receptacle 0.078 –0.495 (0.197) x 0.052 –0.204 (0.108), fully developed in only 5–15 segments; vitellarium reniform, posterior to ovary, 0.059 –0.235 (0.140) x 0.046 –0.153 (0.081); Mehlis’ gland anterior and medial to vitellarium, c. 0.08 in diameter. Uteri paired in each segment, transverse, tubular; early uterus extends from level of ovary to or beyond proximal pole of cirrus sac; developing uterus extends medially and laterally, lateral extensions crossing osmoregulatory canals dorsally; uteri of each segment do not meet in mid-line. Gravid segments 0.130 –0.461 (0.214) long, 4.48–9.98 (7.70) wide. Egg spherical, shell smooth, 0.050 –0.060 (0.056) in diameter; pyriform apparatus conical, with 2 tapering arms, terminating in numerous fine filaments at apex; oncosphere 0.015 –0.025 (0.019) in diameter. Osmoregulatory canals paired; ventral canal generally wider than dorsal, medial to it; ventral canal 0.010 –0.051 (0.034) in diameter, dorsal canal 0.006 –0.020 (0.014) in diameter; transverse canal connects ventral canal at posterior margin of each segment; accessory canals absent.

Remarks. This distinctive species was found only in O. unguifera in Queensland. It is much shorter and broader than any other species though the variation in shape may be due in part to differing methods of fixation used. The scolex and suckers of this species are much larger than any other members of the complex and a neck is lacking. This species is distinguished by its long cirrus sac extending well beyond the osmoregulatory canals, by the very large, elongate seminal receptacle and by the large number of testes (93–128) per segment. The testes were extremely difficult to count in this species as they occur in several dorso-ventral layers; counting was achieved by drawing the testes and then counting them from the drawing. The egg of this species is also distinctive with the pyriform apparatus terminating in two arms. Among congeners, a similar pyriform apparatus is known only from P. diaphana , a parasite of the bile ducts of the southern hairy-nosed wombat, Lasiorhinus latifrons , P. pulchella sp. nov. from the quokka, Setonix brachyurus and P. corniculata sp. nov. from the bile ducts of the spectacled hare wallaby, Lagorchestes conspicillatus .

The type specimens have been selected from the material used in the molecular study of Beveridge et al. (2007) which showed that the single specimen examined from O. unguifera was genetically distinct from all other bile duct cestodes.

Beveridge et al. (1992) reported this cestode in 100% of the 13 O. unguifera examined for parasites in northern Queensland.