Monobothrioides zuheiri, Scholz & Brabec & Hrubá & Jirků, 2021

Scholz, Tomáš, Brabec, Jan, Hrubá, Kateřina & Jirků, Miloslav, 2021, High species diversity of fish tapeworms in congeneric hosts in Africa: revision of Monobothrioides (Cestoda: Caryophyllidea), including description of two new species and molecular phylogeny, Organisms Diversity & Evolution (New York, N. Y.) 21 (2), pp. 447-466 : 459-461

publication ID	https://doi.org/ 10.1007/s13127-021-00492-1
persistent identifier	https://treatment.plazi.org/id/836E8792-0606-FFC3-FCF6-FA9CFE2A98F7
treatment provided by	Felipe
scientific name	Monobothrioides zuheiri
status	sp. nov.

Treatment

6. Monobothrioides zuheiri n. sp. ( Fig. 7 View Fig )

Material studied: 14 stained and mounted specimens and 9 slides of histological sections from Auchenoglanis occidentalis (SUD 157, 158); 2 spec. from A. biscutatus (SUD 120, 160); all specimens from White Nile at Kostí, Sudan (13.18333, 32.66667), collected by T. Scholz on 25 and 27 March 2006.

Description (based on 11 hot formalin-fixed specimens from A. occidentalis ; for measurements, see Table 2). Caryophyllidea , Lytocestidae . Body small, slender, digitiform (rod-like), with almost same width throughout its length, maximum width at posterior region ( Fig. 7a View Fig ) or scolex level ( Fig. 7b View Fig ). Longitudinal musculature formed by individual muscle fibres surrounding vitelline follicles (outer muscles— Fig. 7g View Fig ) and testes (inner longitudinal muscles— Fig. 7g View Fig ); laterally, inner longitudinal musculature extended around lateral osmoregulatory canals ( Fig. 7g View Fig ). Longitudinal excretory canals few, mostly cortical ( Fig. 7g View Fig ). Excretory bladder large, wide, ampulla-shaped, near posterior extremity; excretory pore terminal.

Scolex small, subconical, indistinctly separated from neck region, with weakly developed slightly convex apical end and very few, short longitudinal grooves ( Fig. 7a–c, f View Fig ). Wide transverse band of darkly stained cells situated between scolex and neck region ( Fig. 7a–c, f View Fig ).

Testes medullary, widely oval to spherical, relatively few (precise number not reliably countable), in two dense layers ( Fig. 7g View Fig ) and 2–3 irregular rows, beginning always anterior to first vitelline follicles ( Fig. 7a–c View Fig ); posteriorly, testes not reaching to cirrus-sac ( Fig. 7a, d, e View Fig ). Vas deferens voluminous, forming numerous loops anterior to cirrus-sac, surrounded by vitelline follicles ( Fig. 7e View Fig ). Cirrus-sac thick-walled, relatively small, widely oval to subspherical, containing sinuous sperm duct (internal vas deferens) and muscular cirrus ( Fig. 7a, e View Fig ). Male gonopore median, widely oval, at short distance anterior to female gonopore (common genital atrium absent) ( Fig. 7d, e View Fig ).

Ovary follicular, bilobed, H-shaped, near posterior extremity ( Fig. 7a, e View Fig ); ovarian wings cortical; anterior arms longer than posterior ones ( Fig. 7a, e View Fig ); ovarian isthmus medullary. Vagina tubular, slightly sinuous, lined with chromophilic cells, opening with terminal (distal) end of uterus to female gonopore; anterodorsal to ovarian isthmus, vagina enlarged to form subspherical seminal receptacle ( Fig. 7e View Fig ).

Vitelline follicles numerous, cortical ( Fig. 7g View Fig ), subspherical to spherical, not decreasing in size towards neck region. Follicles begin always posterior to first testes ( Fig. 7ac View Fig ); posterior extent of follicles variable ( Fig. 7a View Fig ), but always posterior to cirrus-sac ( Fig. 7d View Fig ), often reaching to ovarian wings ( Fig. 7e View Fig ); postovarian follicles absent ( Fig. 7a, e View Fig ).

Uterus tubular, strongly coiled; preovarian uterine region relatively short, lined partially or completely with vitelline follicles ( Fig. 7a, d, e View Fig ); uterine glands extensive, lining middle part of uterus anterior to ovarian isthmus ( Fig. 7e View Fig ). Female gonopore transversely oval, narrow, posterior to male gonopore ( Fig. 7d, e View Fig ). Eggs oval, operculate, unembryonated i.e. without fully formed oncosphere.

Type host: Auchenoglanis occidentalis ( Siluriformes : Claroteidae ).

Additional definitive host: Auchenoglanis biscutatus ( Siluriformes : Claroteidae ).

Site of infection: Intestine.

Infection rate: See Table 2.

Type locality: White Nile at Kostí , Sudan (13.18333, 32.66667) GoogleMaps .

Type material: Holotype and 3 paratypes (specimens from A. occidentalis SUD 158, White Nile, Sudan, collected on 27 March 2006 — IPCAS C-868 /1); 1 paratype (specimen from A. occidentalis SUD 158, White Nile, Sudan —MHNG-PLAT 0137394).

Distribution: Nile River basin ( Sudan).

Etymology: The new species is named after Zuheir N. Mahmoud, Faculty of Science, University of Khartoum, who perfectly organised three sampling trips of two of the present authors (TS and MJ) to the Sudan in 2006, 2008 and 2011, and helped considerably with obtaining fish and their parasitological examination.

Representative DNA sequences and phylogenetic relationships: two representatives from two host species had a unique lsr DNA sequence. Molecular data did not resolve the phylogenetic position of M. zuheiri n. sp., but validity of the species was supported by the data ( Fig. 1 View Fig ).

Differential diagnosis: Monobothrioides zuheiri n. sp. can be distinguished from other species of Monobothrioides , including M. longicollis n. sp. described from the same fish host (see above), by a small (length of 10–13 mm), cylindrical body, with almost the same width throughout the body length ( Fig. 7a View Fig ), a small scolex, indistinctly separated by short and wide neck from the remaining body, and tapered anteriorly ( Fig. 7a–c View Fig ), more anterior position of the testes compared to the first vitelline follicles ( Fig. 7a–c View Fig ), a small, subspherical to spherical cirrus-sac ( Fig. 7a, e View Fig ) and large, ampulla-shaped excretory bladder ( Fig. 7a, e View Fig ). Molecular data strongly support validity of the new species but do not resolve its relationships to other species of the genus ( Fig. 1 View Fig ).

Remarks: The new species was found in a single locality (White Nile at Kostí) and only in 2006 (but only two Auchenoglanis catfish were examined in 2008; one harboured M. longicollis n. sp.). In A. biscutatus from the Sudan (host SUD 160), both new species of Monobothrioides were found, even though only a single specimen of each species. Unfortunately, none of three scoleces used for SEM observation was in good shape to be used.