Monopylidium australiense, Mariaux & Georgiev, 2018

Mariaux, Jean & Georgiev, Boyko B., 2018, Seven new species of cestode parasites (Neodermata, Platyhelminthes) from Australian birds, European Journal of Taxonomy 440, pp. 1-42 : 13-16

Monopylidium australiense sp. nov.

urn:lsid:zoobank.org:act:DB89AB09-63A2-43DB-9F30-5C9D41424955

Figs 12–16 , Table 3

Etymology

The specific name is derived from the country where the material was found.

Material examined

Holotype

AUSTRALIA: Victoria, Healesville Sanctuary , 37°41′ S, 145°32′ E, 4 Oct. 1994, Peter Holz leg. (AHC 36480, field number 94/773).

Paratypes

AUSTRALIA: about 24 specs, same datas as for holotype (AHC 36481–36486).

Other material

AUSTRALIA: 2 specs, Victoria, Healesville, 3 Aug. 1991, David Middleton leg. (AHC 22931, 36487); 1 spec., Victoria, Sherbrooke, 37°53′ S, 145°22′ E, 2005, Peter Holz leg (AHC 29271); 1 spec., Victoria, Healesville, 2006, Peter Holz leg. (AHC 29281).

Type host

Menura novaehollandiae Latham, 1801 (syn. M. superba Dacies, 1820 ) ( Passeriformes , Menuridae ).

Site of infection

Small intestine.

Intensity

About 25 specimens in a single host.

Description

Body very small, up to 6.5–8.1 (7.3, n = 7) mm long, consisting of 39–53 proglottides; maximum width 600–725 (694, n = 9) at level of gravid proglottides. Proglottides craspedote, mostly wider than long, but shape depending on contraction. Ventral osmoregulatory canals with posterior transverse anastomoses in each proglottis. Strong longitudinal muscular bundles. Scolex 258–305 in diameter (280, n = 6), slightly wider than neck, widest at level of suckers ( Fig. 12 ). Neck poorly or not marked. Suckers elongated, very muscular, with irregular margins, 130–150 in diameter (132, n = 27). Rostellar pouch strong, musculo-glandular, usually with distinctive widening anterior to suckers, extending beyond level of posterior margin of suckers and becoming much narrower; often folded posteriorly, 270 × 112 (224–320 × 105–130, n = 6). Rostellum muscular, mushroom-shaped 135–150 × 55–83 (144 × 73, n = 3), with distinct apical pad. Rostellar hooks 20–21 in number, in two regular rows, sub-equal; anterior hooks 23–26 (24.2, n = 24) long, posterior hooks 22.5–25.0 (23.7, n = 26) long; all hooks of similar shape, with straight handle, strong short guard and very short blade; small epiphyseal-like outgrowth at tip of handle ( Fig. 13 ). Neck short, proglottization distinct at 25–65 (46, n = 6) from posterior margin of suckers. Genital pores at border of first third of lateral proglottis margin, irregularly alternating in short series, rarely more than 2 (maximum observed 4) consecutive pores on a single side. Genital ducts passing between osmoregulatory canals. Genital atrium infundibular.

Testes large, 16–29 in number (24, n = 52), in median field of proglottis, in double, sometime triple, compact posterior layer, often overlapping vitellarium and ovary. External vas deferens extremely developed, massive and highly convoluted, antero-central, often covering cirrus-sac. Cirrus-sac cylindrical, sometimes slightly wider distally, 86–138 × 26–38 (113 × 33, n = 43), crossing excretory canals and half of it might be situated in median field ( Fig. 14 ). Cirrus 10–12 in diameter, armed with well developed spines situated on part of it with length 50. Internal vas deferens convoluted.

Vitellarium central, oval, mostly regular, composed of few compact lobes. Ovary central, massive, biwinged, multilobate, filling entire width of median field when fully developed, sometimes even slightly crossing lateral osmoregulatory canals. Mehlis’ gland central, overlapping seminal receptacle but not always distinct. Seminal receptacle elongated, anterior to vitellarium and between wings of ovary. Vagina thin-walled with discrete basal muscular sphincter; opening posteriorly to cirrus-sac, sometimes partly overlapping it; lined with thin spines in its distal copulatory part ( Figs 14–15 ).

Uterus initially broadly reticulate, developing quickly over whole median field width and extending in lateral field. With further development, uterus becoming compact, saccular, with few deep lobes. Oncospheres slightly oval, 19–24 (21, n = 20) in diameter. Eggs with thin outer shell provided with two big and distinct nuclei; embryophore spherical, thick ( Fig. 16 ). Central embryonic hooks 11 long, lateral embryonic hooks 10 long.

Observations on additional material (not belonging to the type series)

AHC 22931: about 40, extremely small specimens, shorter than 2 mm, maximum width 510, composed of fewer than 20 proglottides but with extremely rapid development. Some early gravid proglottides present. General characters in accordance with the above description to the exception of slightly wider rostella [85–105 (95, n = 10)] and slight variation in number of rostellar hooks (single specimens with 19, 22 or 23 rostellar hooks).

AHC 29271: two slides with fragments of generally poor quality. The observable characters fit the above description.

AHC 29281: a single slide composed of fragments of smaller worms, similar to material from host 22931. Slightly smaller scoleces (200–225 in diameter).

Remarks

In its report on helminth parasite of lyrebirds in Australia, Johnston (1913) described a new acanthocephalan but no cestode. Much later, McOrist & Scott (1989) examined superb lyrebirds suffering from enteritis that was caused by acanthocephalan infections in Southern Victoria and noted the presence of “occasional cestodes of the genus Choanotaenia ” in the specimens they studied. To the best of our knowledge, these are the only helminthological reports for these birds.

To our knowledge, there are only two reports of a Monopylidium in Australia. Johnston (1909) mentioned the cosmopolitan species M. passerinum (Fuhrmann, 1907) in Passer domesticus L. in New South Wales and gave a detailed description. This species differed from the present material by several characters including significantly shorter rostellar hooks ( Table 3 ). Monopylidium fieldingi has also been reported from Australia in the butcherbird Cracticus destructor Temminck, 1824 [now C. torquatus (Latham, 1801) ] in North Queensland ( Maplestone & Southwell 1923). However, this taxon has a clearly different anatomy, in particular the presence of 80 rose-thorn shaped hooks in two rows, and is now placed in the genus Cracticotaenia Spasskii, 1966 (Metadilepididae) (see below).

Here, we follow the concept of Spasskii (1993) as updated by Bona (1994) for the definition of Monopylidium . Thus, Icterotaenia Railliet & Henry, 1909 is considered a synonym and some species validated by Spasskii (1993) are now placed in different genera (like Cuculincola Bona, 1994 or Spasspasskya Bona, 1994 ). Globally, about 25 species of Monopylidum are presently recognized ( Table 3 ), although the status of some of them remains equivocal. Our material can easily be differentiated from nearly all of them, although M. attenuatum (Dujardin, 1845) and M. tandani ( Singh, 1964) present relatively similar characteristics. However, the former shows a smaller rostellum bearing hooks of different shape, larger oncospheres and embryonic hooks than those of our specimens. It may also have unarmed cirrus ( Spasskaya & Spasskii 1977). The latter is a short worm with few (<20) proglottides, hooks with longer blades and shorter handles and an unarmed cirrus. It is only known from Myophonus caeruleus temminckii Vigors, 1831 , a trush found in the Himalayan region ( Singh 1964).

Consequently, Monopylidium australiense sp. nov. is the single known cestode parasitizing this endemic host.

Figures

Figs 12–16. Monopylidium australiense sp. nov. 12. Scolex. 13. Hooks. 14. Mature proglottis. 15. Terminal genitalia. 16. Eggs. Scale bars: 12, 14 = 100 µm; 13, 16 = 20 µm; 15 = 50 µm.