Dictymetra longiuncinata, 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 : 22-27

publication ID

https://doi.org/10.5852/ejt.2018.440

publication LSID

lsid:zoobank.org:pub:DB80A42B-5C53-455B-86A4-2003D6F03522

DOI

https://doi.org/10.5281/zenodo.3846844

persistent identifier

https://treatment.plazi.org/id/71A5F386-689C-4416-A46C-8FC5078441E4

taxon LSID

lsid:zoobank.org:act:71A5F386-689C-4416-A46C-8FC5078441E4

treatment provided by

Valdenar

scientific name

Dictymetra longiuncinata
status

sp. nov.

Dictymetra longiuncinata sp. nov.

urn:lsid:zoobank.org:act:71A5F386-689C-4416-A46C-8FC5078441E4

Figs 23–28 View Figs 23–28

Etymology

From Latin longus (long) and uncinus (hook) in reference to the large rostellar hooks of this species.

Material examined

Holotype

AUSTRALIA: Queensland, Yeppoon , 23°8′ S, 150°44′ E, 30 Sep. 1999, Ian Beveridge leg. ( AHC 36496 View Materials ).

GoogleMaps

Paratypes

AUSTRALIA: about 44 specs, same data as for holotype ( AHC 36497 View Materials –36515).

Host

Esacus magnirostris (Vieillot, 1818) (syn. Burhinus magnirostris ) ( Charadriiformes , Burhinidae ).

Site of infection

Small intestine.

Intensity

About 45 specimens in a single host.

Description

Body small, 10.1–13.9 mm (n = 2) long with maximum width 950–1400 (1144, n = 8) at level of early gravid proglottides. Most complete specimen consisting of 76–83 proglottides. Proglottides markedly craspedote, wider than long, progressively becoming longer, but mostly remaining wider than long except for a few terminal or exceptionally extended ones. Osmoregulatory canals only very partially visible. Scolex rounded, in continuity with strobila (without a marked neck); diameter 470–665 (551, n = 7) ( Fig. 23 View Figs 23–28 ). Proglottization starting precociously, often just behind suckers. Suckers rounded to slightly oval, muscular, unarmed, 230–300 (262, n = 32) in diameter. Rostellar apparatus mostly muscular, with a layer of glandular tissue at mid-length of rostellar sac. Rostellar sac well-delineated, with cylindrical anterior part and markedly tapering posterior part, extending well beyond level of posterior margin of suckers and sometimes into first proglottides, 475–690 × 150–210 (608 × 178, n = 7). Rostellum strongly muscular, with expanded anterior part bearing rostellar hooks, 400–620 × 110–145 (537 × 133, n = 8). Rostellar hooks ( Fig. 24 View Figs 23–28 ) in two regular rows, 20 (n = 6) in number, long and robust, curved overall; blade longer than handle. Anterior hooks 119–125 (121.5, n = 13) long, posterior hooks 124–135 (129.5, n = 15) long. Genital pores situated at border of anterior 40% of lateral proglottis margin, alternating irregularly in very short series, e.g., 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 1, 1, 1 or 1, 1, 2, 1, 1, 3, 1, 1, 1, 1; no more than 3 consecutive pores observed on one side. Genital ducts passing between osmoregulatory canals. Genital atrium as simple depression without particular structures. Genital papilla occasionally expressed in some proglottides.

Testes numerous, 18–28 (22, n = 19) in number, large, reaching 75–92 (84, n = 19) in diameter, situated in 2–3 layers, in one continuous and compact posterior field, extending in anterior direction to level of antiporal wing of ovary ( Fig. 25 View Figs 23–28 ). External vas deferens 13–18 in diameter, highly convoluted and particularly voluminous in antero-poral part of median field, sometimes slightly overlapping cirrussac, seminal receptacle or even testes. Cirrus-sac elongate, 137–180 × 33–45 (159 × 38, n = 44), delicate, slightly oblique, usually straight but with distal quarter sometimes bent anteriorly, crossing osmoregulatory canals, rarely not. Internal vas deferens forming several coils. Cirrus cylindrical, 7.5 in diameter, ornamented with tuft of thin hair-like bristles ( Figs 26–27 View Figs 23–28 ).

Vitellarium central, compact, irregularly shaped and slightly lobated. Ovary transversely elongated, bi-alate, lobate, antiporal wing larger than poral wing; the latter mostly covered by vas deferens. Mehlis’ gland not observed. Empty seminal receptacle round, becoming oval when filled, reaching up to 135 × 68, close to proximal extremity of cirrus sac. Vagina, large, opened posteriorly to male pore, mostly straight and transverse, parallel to cirrus-sac, thin-walled. No sphincters or other ornamentations.

Uterus starts its development in late mature proglottides as diffuse reticulum occupying the whole median field and part of lateral fields, and developing into dense network of tube and chambers. Eggs large, outer shell with polar extensions ( Fig. 28 View Figs 23–28 ). Complete eggs with external membrane difficult to see in utero but reaching at least 85 (without extensions). Embryophores oval, 53–65 (59.5, n = 15) in

diameter. Oncospheres 38–46 (42, n = 22) in diameter. Embryonic hooks: central 20–21.5 (21, n = 8) long, lateral 17–20 (19, n = 16) long.

Remarks

This material is partly macerated, with many fragments contracted and overall in an average state of conservation. This explains the lack of data for several characters such as osmoregulatory canals or Mehlis’ gland. Our observations, nevertheless, allow for a description that fits the definition of Dictymetra , in particular because of its characteristic scolex structure and tuft of setae in the genital atrium and on the cirrus. The genus Dictymetra is typically found in various families of Charadriiformes , including Burhinidae ( Bona 1994) (see remarks above for D. gerganae sp. nov.) and is cosmopolitan ( Table 4 View Table 4 ). Our material can easily be differentiated from other species in the genus because of its very long hooks and large rostellum . Similar characters are only found in D. laevigata (Rudolphi, 1919) , another parasite of thick-knees, and D. paranumenii ( Clark, 1952) , a parasite of curlews in North America. It differs from both by its smaller number of testes. Additionally, it can be distinguished from the former species by its larger cirrus-sac, and from the latter by its shorter strobila ( Table 4 View Table 4 ).

In addition, the genus Stenovaria Spasskii & Borgarenko, 1973 also resembles our material. It differs from Dictymetra by relatively minor characters related to genital pore alternation, the position of genital ducts in relation to osmoregulatory canals and the absence of armament of long setae on the cirrus and (or) genital atrium. The genus was erected by Spasskii & Borgarenko (1973) and is presently recognized as valid ( Bona 1994, Mariaux et al. 2017). It includes 2 species found in thick-knees: Stenovaria facile ( Meggitt, 1927) Spasskaya & Spasskii, 1978 and S. falsificata ( Meggitt, 1927) Spasskii & Borgarenko, 1973 that deserve to be compared to our material. Both differ from it by their much shorter hooks and smaller strobila. In addition, the former species also shows a smaller cirrus-sac and the latter has a larger cirrus-sac and a smaller number of testes. In consequence we consider the present material as a new species that we name Dictymetra longiuncinata sp. nov.

Table 4 (continued on next page). Comparison of two new Dictymetra Clark, 1952 species with the presently recognized species in the genus and with “long” Liga Weinland, 1857 species (see text). All data as reported in Spasskaya & Spasskii (1978) for Dictymetra and Spasskaya & Spasskii (1977) for Liga except Burt (1940) for D. dispar, Clark (1952) for D. paranumenii, Fuhrmann & Baer (1943) for D. riccii and Spasskaya & Spasskii (1973) for D. volvulus. Note that values reported by various authors for D. laevigata (Rudolphi, 1919) and D. volvulus (Linstow, 1903) vary to a large extent (Spasskaya & Spasskii 1978). Dictymetra paranumenii and D. radiaspinosa have rows of small spines on rostellum.

Species Host family Type locality Body maximum length (mm) Scolex diameter Suckers diameter Rostellar sac Rostellum Hooks number Anterior hooks length Posterior hooks length Testes number Cirrus sac
D. gerganae sp. nov. Podargidae Australia 72 305–360 145–175 230–292 × 118–145 195–212 × 98–132 24 46–53 50–56 60–77 100–132 × 65–83
D. longiuncinata sp. nov. Burhinidae Australia 13.2 470–665 230–300 475–690 × 150–210 400–620 × 110–145 20 119–125 124–135 18–28 137–180 × 33–45
D. radiaspinosa Mathevossian, 1953 Scolopacidae USA 15–25 247–330 204–231 83–115 24 65–68 15–17 146–198 × 23–25
D. belopolskajae Spasskaya & Spasskii, 1973 Alaudidae Russian Arctic 80 313 123 347–408 × 106–123 252–308 × 95–112 20 56–67 18–30 106 × 39
D. discoidea (Beneden, 1868) Ciconiidae Palaearctic 370–400 210 100 22–23 37–38 33–34 40–45 250–270 × 65–70
D. dispar ( Burt, 1940) Charadriidae Sri Lanka 40–50 330–385 143–175 325 × 110 175–229 × 65–88 24 41–45 44–49 18–28 170–200 × 38–41
D. ganii Spasskaya & Shumilo, 1971 Scolopacidae Moldavia 70 695 335 246 × 140 162 × 67 22–24 28 (~40) 94 × 67
D. laevigata (Rudolphi, 1819) Charadriiformes Palaearctic 75 650 428 314 × 141 20 104–106 109–112 50 98 × 48
D. numenii (Owen, 1946) Scolopacidae Holarctic 14–20 192–538 133–221 124–162 22 99–103 42–46 111–140 × 44–58
D. nymphaea (Schrank, 1790) Charadriiformes Palaearctic 25–30 210–220 80–85 80–85 24 60–80 30–36 100–130 × 38–55
D. paranumenii (Clark, 1952) Scolopacidae USA 150–300 476–523 143–165 408–620 × 176–204 442–516 × 136–176 20 100–105 110–115 35–40 132–165 × 33–60