Emberizotaenia aeschlii Mariaux & Georgiev 2020, sp. nov.

Emberizotaenia aeschlii sp. nov.

urn:lsid:zoobank.org:act: AF7C4CCB-7621-4DA1-B97E-2DD43AAFC4E2

Figs 1–3, Table 1

Etymology

The species is dedicated to the late Prof. André Aeschlimann, parasitologist and mentor of the senior author, who was familiarly known as “Aeschli” to his colleagues and students.

Material examined

Holotype

MALAYSIA • Selangor, University of Malaya’s Gombak Field Station; 3.32° N, 101.77° E; 280–350 m a.s.l.; 31 Jul. 2010; no molecular voucher; MHNG-PLAT-120682.

Comparative material

AUSTRALIA • transverse sections of syntypes of Emberizotaenia chlamyderae (Krefft, 1871) Bona, 1994 from Chlamydera maculata (Gould, 1837) (Passeriformes, Ptilonorhynchidae); SAM-AHC 20445.

Type host

Tricholestes criniger (Blyth, 1845) (Passeriformes, Pycnonotidae).

Prevalence

17% (1/6).

Description

Body small, 22.5 mm long, with maximum width 1075 at level of pregravid proglottides; consisting of 115 proglottides (last proglottides pregravid). Proglottides craspedote, always wider than long. Scolex rounded, not delineated from neck, 430 in diameter (Fig. 1). Suckers rounded, 185–200 (194, n = 4) in diameter; muscular, unarmed. Rostellar apparatus unarmed, weakly muscular, with well-developed glandular tissue within rostellar sac, especially in its posterior half. Rostellar sac regular, cylindrical, almost reaching level of posterior margin of suckers, 225 × 88. Rostellum discrete, poorly delineated and very weak, 64 × 20, glandular. Proglottization distinct at 300 from posterior margin of suckers. Genital pores situated in anterior 25% of length of lateral proglottis margin, irregularly alternating in very short series, e.g., 2, 2, 2, 1, 2, 1, 3, 1, 3, 1, 2, 1; no more than 4 consecutive pores observed on one side. Ventral osmoregulatory canals up to 40 wide, connected posteriorly in each proglottis by transverse anastomosis. Dorsal osmoregulatory canals 6–7 wide. Genital ducts passing between osmoregulatory canals. Genital atrium small, sink-shaped, up to about 18–22 deep and 15–17 in diameter.

Testes 26–34 (29, n = 14) in number; in 2 or 3 layers, in one continuous posterior field, sometimes overlapping osmoregulatory canals and often overlapping posterior lobes of ovary and vitellarium (Fig. 2). External vas deferens convoluted in antero-poral part of median field. Cirrus-sac elongate, 170–212 × 36–50 (191 × 43, n = 20), usually straight, crossing osmoregulatory canals; distal extremity with large cells (Fig. 3). Internal vas deferens forming several coils, mostly in proximal half of cirrus sac. Cirrus unarmed, about 100–130 long and usually straight when invaginated.

Vitellarium central, compact, transversely elongate, variable in shape but often forming a flattened V or reniform. Ovary antero-central, transversely elongate, bi-alate, multilobate, antiporal wing larger than poral wing; not overlapping longitudinal osmoregulatory canals. Mehlis’ gland subglobular, anterior to vitellarium. Seminal receptacle round, becoming more oval when full but never elongated, reaching up to 190 × 145 in pregravid proglottides, dorsal and between ovary wings. Vagina opens posterior to male pore, straight and transverse, parallel to cirrus-sac; thick-walled, surrounded by a loose sheath of large cells irregularly positioned along entire canal; no vaginal sphincter (Fig. 3).

Uterus starts its development in late mature proglottides as a diffuse ventral reticulum, progressively forming numerous small lobes and occupying entire median field; crossing osmoregulatory canals and extending into lateral fields. Uterus eventually becoming sacciform with deep septa. Developing oncospheres round, 19–21 in diameter, no fully developed eggs or embryonic hooks observed.

Remarks

Dilepidids with a reduced, unarmed, apical apparatus belong to a number of genera. An important differentiating character for distinguishing among them is the presence (or not) of a rudimentary unarmed rostellum, or “bulb” (Bona 1994). This structure is a diagnostic character of two genera, Eburneotaenia Bona, 1994, with type species E. eburnea (Mariaux & Vaucher, 1988), characterised also by the presence of sucker armature consisting of small punctiform spines (see Mariaux & Vaucher 1988), and Emberizotaenia Spasskaya, 1970, which has unarmed suckers. Our specimen has such an unarmed bulb, albeit weak, and has unarmed suckers. Therefore, it belongs to Emberizotaenia, a genus known from birds of the order Passeriformes in the Palaearctic Region and in Australia. Bona (1994) mentioned Africa and Sri Lanka in the geographical range of this genus but without further explanation or reference; we consider the information about these geographical areas may come from his personal unpublished data.

The new species described here essentially fits the generic diagnosis proposed by Bona (1994). There is an exception related to the number of testes, which are “numerous” (26–34) in our material, instead of “very numerous” as mentioned in the generic diagnosis; according to Bona (1994), the adopted range for “very numerous testes” refers to “from about 36 to 60, seldom more”. However, the type species E. reductorhyncha (Spasskaya, 1957), as well as E.skrjabiniana (Spasskaya, 1958), also have “numerous” testes (Table 1), i.e., between 14 and 35 according to Bona’s (1994) definition. In addition, we could not observe the osmoregulatory canals forming a network posterior to the scolex in our specimens; this character may, however, be difficult to observe depending on the state of conservation and the fixation of the material, and has not been reported in the original descriptions of the majority of the known species. Therefore, we doubt that it is a reliable character to be used for generic differentiation.

Currently, the genus Emberizotaenia includes 4 species:

1. Emberizotaenia reductorhyncha (Spasskaya, 1957) (type species) [Anomotaenia reductorhyncha Spasskaya, 1957; Unciunia reductorhyncha in Matevosyan 1963; Ptilotolepis reductorhyncha in Spasskaya & Spasskii 1977], originally described from Poecile cinctus (Boddaert, 1783) (syn. Parus cinctus) (Paridae) from Vilyuyskiy Rayon, Yakutia, Russia (Spasskaya 1957). Subsequently, this species was redescribed and illustrated from “ Parus atricapillus ” from Tuva (Russia); however, Poecile atricapillus is currently believed to represent a North American species (Lepage 2019) and this record probably refers to P. montanus Conrad von Baldenstein, 1827. Other host records are those from P. palustris Linnaeus, 1758 from Tuva (Spasskaya & Spasskii 1971) and from Parus major Linnaeus, 1758 from Ukraine (Salamatin 1999). The records of E. reductorhyncha from Turdus philomelos Brehm, 1831 (= Turdus ericetorum) from Moldova (Shumilo & Spasskaya 1975; Spasskaya & Spasskii 1977) and Kaliningradskaya Oblast’ of Russia (Galkin 1981) most probably refer to another congeneric species, E. raymondi (see Georgiev & Genov 1993). Therefore, E. reductorhyncha is a specific parasite to birds of the family Paridae known from the Northern Palaearctic.

2. Emberizotaenia skrjabiniana (Spasskaya, 1958) Spasskaya, 1970 [Anomotaenia skrjabiniana Spasskaya, 1958; Pseudanomotaenia skrjabiniana in Matevosyan 1963; Ptilotolepis skrjabiniana in Spasskaya & Spasskii 1977] from Emberiza leucocephalos Gmelin, 1771 (Emberizidae) from Tuva (Russia) (Spasskaya 1958). Kornyushin (1972) reported this species from Ukraine but without providing data on its host and morphology. Spasskaya & Spasskii (1977) mentioned it from Galerida cristata (Linnaeus, 1758) (Alaudidae) from Nakhchivan Autonomous Republic (Transcaucasia) on the basis of the unpublished dissertation by Sadykhov but this record needs additional confirmation. Ryšavý (1979) believed that the original description by Spasskaya (1958) had been based on specimens with lost rostellar hooks and identified cestodes with armed rostella from Fringilla coelebs Linnaeus, 1758 (Fringillidae) from Czechia as this species; the details in the description given by Ryšavý (1979) do not allow the identification of his cestodes at the generic level. Therefore, the only reliable report of E. skrjabiniana is the original description by Spasskaya (1958).

3. Emberizotaenia raymondi (Gigon & Beuret, 1991) [Unciunia raymondi Gigon & Beuret, 1991; Ptilotolepis raymondi in Georgiev & Genov 1993; Ptilotolepis philomelae Okulewicz, 1991] from Turdus philomelos (Turdidae) from Switzerland (type locality) (Gigon & Beuret 1991), Poland (Okulewicz 1991), Bulgaria (Georgiev & Genov 1993) and, possibly from Moldova and Kaliningradskaya Oblast’, Russia (as Emberizotaenia reductorhyncha, see above). Therefore, for the moment, this species is a specific parasite of Turdus philomelos known from Europe only.

4. Emberizotaenia chlamyderae (Krefft, 1873) [Taenia chlamyderae Krefft, 1873; Choanotaenia chlamyderae in Johnston 1911; Icterotaenia chlamyderae in Baer 1925; Paricterotaenia chlamyderae in Fuhrmann 1932; Polycercus chlamyderae in Schmidt 1986] from Chlamydera maculata (Gould, 1837) (Ptilonorhynchidae) from New South Wales, Australia, known from its original description (Krefft 1873) and a drawing of the scolex by Bona (1994). Unfortunately, most of Krefft’s material, including specimens observed by Bona, seems to be lost, with only 3 slides of sections remaining. These allowed us to obtain a few measurements of the cirrus-sac at 111 × 33 (90–137 × 27–41, n = 7), as well as to obtain a very rough estimate of testis number, probably less than 20 (Table 1).

Even in the absence of gravid proglottides, our specimen is unambiguously distinguishable from all of them (Table 1). It differs from E. reductorhyncha by the higher number of testes (26–34 vs 16–20) and a longer cirrus sac (170–212 vs 145); from E. skrjabiniana by its smaller cirrus sac (170–212 vs 248–256) and smaller rostellar sac (225 × 88 vs 320 × 330). Our material is more similar to E. raymondi. Metrical characters in both taxa are very similar, but a number of differences nevertheless allow them to be distinguished morphologically. The most obvious ones are the shape of the rostellar pouch, which is globular in E. raymondi and more elongated in our material, as well as the presence of distinctive large cells making a loose sheath around a strongly walled vagina in the Malaysian material. Additionally, E. raymondi has as larger scolex and suckers; a more elongate cirrus sac, a higher proportion of it extending in median field; and a smaller seminal receptacle. From E. chlamyderae, a species with very poorly known anatomy, our specimen differs by its three times smaller body length, a larger cirrus-sac and, possibly, higher number of testes.

Together with the host and the geographical origin of our material, these observations allow its recognition as a new species, Emberizotaenia aeschlii sp. nov. Pycnonotidae represents a new host family for this genus of cestodes.