Progamotaenia dilatata, Beveridge & Shamsi, 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 : 19-21

Progamotaenia dilatata sp. nov.

( Figs 44–50)

Synonyms: Progamotaenia festiva ( Rudolphi, 1819) in part, Beveridge (1976), Beveridge et al. (1985, 1998), Spratt et al. (1991).

Host: Wallabia bicolor (Desmarest) (Marsupialia: Macropodidae ).

Site in host: bile ducts.

Types: Holotype, Nariel , Victoria (36º 20'S 147º 48'E), coll. D.M. Spratt, 29.v.1974, SAM 29364; 2 paratypes, same data SAM 29365.

Etymology: from dilatatus (= widened) referring to the broad anterior end of this species.

Material examined: From Wallabia bicolor (swamp wallaby): Queensland: 1 specimen, Dingo Beach ( SAM 29370 (S)), 1 specimen, Airlie Beach ( SAM 29376 (S)); 2 specimens, Rockhampton ( SAM 19757 (S)); New South Wales: 6 specimens, Dubbo ( SAM 29368 (S)), 1 specimen, Ourimbah ( SAM 20067(S), 1116(W)), 1 specimen, Nowra ( SAM 21489 (S)); Australian Capital Territory: 1 specimen, Tidbinbilla ( WLHC S310 (S), C235 (W), BMNH 2008.3 .6.12 (S)); Victoria: fragments, Nariel ( SAM 29366 (S), 25408(W)), 3 specimens, Cudgewa ( SAM 20825, WLHC C6 , C12 (S)), 2 specimens, Dartmouth ( SAM 20928) ; 1 specimen, Dixon’s Creek ( SAM 29369 (S)) .

Description: Broad worms, 12–58 (35) long, maximum width 3–8 (5.7) with 92–228 (167) segments in gravid specimens. Scolex 0.85–1.30 (1.06) in diameter, squat, weakly 4-lobed; suckers circular, 0.293 –0.569 (0.436) in diameter. Neck very short. First mature segment 22–41th (32, n=7). Mature segments craspedote, 1.46–2.68 (2.11) wide, 0.065 –0.179 (0.125) long. Genital atrium small, in middle or slightly posterior to middle of lateral segment margin; cirrus sac elongate, extending well beyond osmoregulatory canals, 0.163 –0.598 (0.423) long, 0.046 –0.117 (0.079) wide; cirrus unarmed; internal seminal vesicle occupies approx. 2/3–3/4 of volume of cirrus sac, 0.065 –0.377 (0.243) long, 0.020 –0.052 (0.040) wide; elongate external seminal vesicle, covered with layer of glandular cells, 0.072 –0.208 (0.134) long, 0.033 –0.143 (0.070) wide; vas deferens coils medially, dorsal to uterus; testes arranged in anterior half of segment between osmoregulatory canals; no prominent space between canals and testis fields; testes arranged in 2 dorso-ventral layers, in single band or in 2 separate groups separated by small space. Testes 0.033 –0.065 (0.050) in diameter; testis number 68–78 (75, n=5). Vagina tubiform, lacking glandular investment, opens to genital atrium posterior to cirrus sac, leads to ovoid to subspherical seminal receptacle 0.130 –0.293 (0.212) x 0.052 –0.195 (0.104). Ovary flabelliform, medial to seminal receptacle 0.065 –0.124 (0.085) x 0.033 –0.078 (0.051), fully developed in few segments; vitellarium reniform, posterior to ovary, 0.078 –0.195 (0.124) x 0.046 –0.098 (0.066); Mehlis’ gland anterior and medial to vitellarium. 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 0.147 –0.406 (0.241) long, 2.28–4.23 (3.27) wide. Egg spherical, shell smooth, 0.055 –0.062 (0.058) in diameter; pyriform apparatus conical, terminating in numerous fine filaments at apex; oncosphere 0.012 –0.016 (0.013) in diameter. Osmoregulatory canals paired; ventral canal generally wider than dorsal, medial to it; ventral canal 0.013 –0.046 (0.023) in diameter, dorsal canal 0.007 –0.026 (0.013) in diameter; transverse canal connects ventral canal at posterior margin of each segment; accessory canals absent.

Remarks. P. dilatata differs from P. festiva in having a very short neck and a cirrus sac which extends well into the medulla. It differs from P. fellicola and P. aemulans in lacking a distinctive space between the testis fields and the osmoregulatory canals, and from P. pulchella in that the testes are usually distributed in a single band rather than being invariably distributed in two separate groups. It can be distinguished from P. corniculata by the long neck of the latter species and by the fact that the pyriform apparatus of P. corniculata terminates in two separate horns without reflexed filaments. P. dilatata differs from P. onychogale in being an elongate cestode rather than being short and foliiform; P onychogale has up to 84 segments while P. dilatata has 92–228 segments. P. dilatata differs from P. adspersa in M. irma in that the cirrus sac of the latter species extends just across the osmoregulatory canals in to the medulla while approximately 50% of the cirrus sac of P. dilatata lies within the medulla. In addition, the size of the suckers of P. dilatata (0.29–57 (0.44) mm) exceeds those of P. adspersa (0.18–0.26 (0.23) mm). P. dilatata is readily distinguishable from P. vombati in the shape of the scolex ( Figs. 45, 46) and in the number of testes per segment which are 83–122 (98) in P. vombati and 68–78 (75) in P. dilatata .