Paroniella blanchardi ( Parona, 1897 )

Beveridge, Ian & Smales, Lesley R., 2017, Cestode Parasites (Platyhelminthes) of Rodents from New Guinea and Adjacent Islands with a Redescription of Paroniella blanchardi (Parona, 1897) (Davaineidae), Records of the Australian Museum (Rec. Aust. Mus.) 69 (6), pp. 451-460 : 454-456

Paroniella blanchardi ( Parona, 1897)

Figs. 2–9

Davainea blanchardi Parona, 1897

Brumptiella blanchardi ( Parona, 1897) , Lopez-Neyra, 1931

Delamurella blanchardi ( Parona, 1897) , Spasskii & Spasskaya, 1976

Material examined. From Paramelomys lorentzii (Lorentz’s paramelomys): Wokan Island, Aru Islands , West Papua ,

5°37'S 143°30'E (W48821); from Rattus feliceus Thomas, 1920 (spiny Seram Island rat): Piliana Village, Seram , Maluku Province , 3°15'S 129°30'E (W23778) .

Description

Large cestodes up to 110 mm long, 5 mm in width; scolex 0.42–0.50 (0.48, n = 5) in diameter; suckers 0.10–0.14 (0.12, n = 5) in diameter, armed with rows of spines; rostellum 0.17–0.24 (0.20, n = 5) in diameter; internal wall of rostellar sac lined with tiny spines; rostellar hooks c. 125 in number, hammer-shaped, arranged in two circles, 0.025 –0.035 (0.030, n = 5) long; genital pores essentially unilateral; single block of 4 segments with reversed polarity seen in one section of strobila; mature segments elongated laterally, craspedote, 0.17–0.25 (n = 0.21, n = 5) long, 1.84–3.35 (2.47, n = 5) wide, length: width ratio 12; genital atrium close to anterior margin of segment; cirrus sac small, c. 0.10–0.14 long, 0.05 wide, not reaching osmoregulatory canals; distal cirrus armed (visible only in histological sections); vas deferens, sinuous, running along anterior margin of segment; 18–28 (23, n = 5) and 29–40 (34, n = 5) poral and aporal testes respectively; testes 0.04–0.05 (0.05, n = 5) in diameter. Vagina opens to genital atrium posterior to cirrus sac, wall muscular, internal lining of distal vagina armed (visible only in histological sections); female genital complex in mid-line; ovary bilobed, poral lobe slightly smaller, 0.08–0.13 (0.10) × 0.08–0.13 (0.10) with fewer lobules than aporal lobe, 0.12–0.20 (0.17, n = 5) × 0.08–0.11 (0.10, n = 5); Mehlis’ gland posterior to ovarian isthmus, c. 0.04 in diameter; vitellarium lobulate, posterior to Mehlis’ gland, 0.07–0.14 (0.11, n = 5) × 0.05–0.06 (0.06, n = 5); vagina slender; seminal receptacle evident in gravid but not in mature segments; gravid segments 0.35–0.60 (0.52, n = 5) long, 2.70–4.10 (3.20, n = 5) wide, length; width ratio, 6.2; with eggs in individual capsules, capsules 0.025 –0.040 (0.035, n = 5) in diameter; eggs 0.018 –0.025 (0.021, n = 5) in diamEtEr; Egg capsulEs EntirEly fill gravid sEgmEnts, extending beyond osmoregulatory canals; osmoregulatory system highly reticulate; largest vessels in gravid segments 0.03 in diameter. Longitudinal musculature composed of tWO bands Of fibrEs; innEr band Of largEr bundlEs Of up tO 20 fibrEs; 40 bundlEs On Each sidE Of sEgmEnt; OutEr band cOmpOsEd Of individual fibrEs Or bundlEs Of up tO 5 fibrEs; transverse muscle forming a broad band medial to inner longitudinal muscles; dorsoventral muscles scattered, individual.

Remarks. In possessing unilateral pores and a single egg per egg capsule, this species belongs to the genus Paroniella . Sawada (1964) in a comprehensive list of all known species included only a single species of Paroniella from rodents, P. blanchardi ( Parona, 1897) described from Leopoldamys siporamus (Thomas, 1895) (as Mus siporanus ) and Maxomys rajah (Thomas, 1894) (as Mus rajah ) on Sipura Island (as Sipora or Sereinu), part of the Mentawei group of islands Off Sumatra ( ParOna, 1897). NO spEciEs Of Paroniella from rodents has been added since Sawada (1964). The description and illustrations by Parona (1897) are limited in detail, but report a maximum length of 75 mm, a width of 5 mm, with about 300 segments, a scolex 0.5 mm in diameter, a rostellum bearing 70–80 hooks 0.032 mm long and sucker spines 0.006 mm long. Most of the principal dimensions provided by Parona (1897) thus match those of the specimens described above, apart from the number of rostellar hooks. Counting the number of hooks from lateral views of a scolex and then doubling the number gave a value of 70–80, the number estimated by Parona (1897), while examination of an apical view of the scolex ( Fig. 6 ) suggested a number of about 125 hooks. Parona (1897) provided no details of the mature segment such that comparisons with the data presented here are not possible. He illustrated the lateral region of several gravid segments, which indicate that the genital pores were unilateral. In the fragments available for examination here, genital pores were generally unilateral, but one area of strobila was seen in which a series of four segments in a fragment containing 14 segments, exhibited a reverse polarity. The current re-description, while still incomplete due to the poor nature of the material, increases thE knOWn numbEr Of hOst spEciEs and is thE first rEpOrt Of the species from New Guinea.

ThE captiOns tO thE figurEs Of thE Original dEscriptiOn Of this species (p. 124) have November, 1897 as the publication date and in a table of measurements on p. 106, the species is cited as “ D. blanchardi n. sp. Parona, 1897 ”. However, the initial page of the issue of the journal gives the publication date as 1898. In spite of this discrepancy, the citation date has not been altered from that used in the literature.

Joyeux & Baer (1927) recorded P. blanchardi from Thryonomys swinderianus (Temminck, 1827) from Dahomey (Abomey) in Benin and illustrated the scolex and a rostellar hook but provided no description. The same illustrations were used by Artykh (1966) in his summary of the species. Janicki (1906) and Shipley (1908) included the species (as Davainea blanchardi ) in their lists of cestodes from rodents ( Rattus ) known at that time, but did not provide any additional details.

No other species of Paroniella has been reported from rodents apart from a record of P. retractilis (Stiles, 1895) , described initially as a parasite of lagomorphs in North America, and also from Rattus rattus in Benin (Joyeux & Baer, 1927).

Of the various species of Paroniella known from New Guinea ( Sawada, 1964), P. conopophilae (Johnston, 1911) , P. corvina (Fuhrman, 1905) and P. paradisiae ( Fuhrmann, 1909) are known from birds ( Sawada, 1964, Schmidt, 1986), but are readily distinguishable from P. blanchardi using the metrical data provided in Sawada (1964). Paroniella appendiculata ( Fuhrmann, 1909) was described from an unknOWn hOst ( Fuhrmann, 1909), but diffErs frOm P. blanchardi in lacking scolex and sucker spines, in having largEr hOOks (36–43 µm) and in having charactEristically shaped campanulate segments ( Fuhrmann, 1909).

Figures

Figures 2–9. Paroniella blanchardi (Parona, 1897). (2) scolex, dorsoventral view; (3) rostellar hook; (4) sucker spines; (5) Anterior extremity of strobila showing reticulated osmoregulatory system; (6) scolex, apical view; (7) optical transverse section of hand-cut section showing longitudinal and transverse musculature; (8) mature segment; (9) gravid segment. Scale bars: Figs. 5, 8, 9—1.0 mm; Figs. 2, 6, 7—0.1, mm; Figs. 3, 4, to same scale—0.01 mm.