Trypanosoma (Haematomonas) neitzi Dias, 1951 emend. Jordaan, du Preez

Redescription of Trypanosoma (Haematomonas) neitzi Dias, 1951 emend. Jordaan, du Preez & Netherlands

Trypanosoma neitzi Dias, 1951

Trypanosoma mocambicum Pienaar, 1962

Trypanosoma mocambicum Pienaar, 1962 emend. Dvořáková

& Široký, 2015

Type host: Pelusios sinuatus Smith, 1838 ( Testudines: Pelomedusidae ) (syns. Pelusios sinuatus zuluensis and Pelusios sinuatus sinuatus ).

Other hosts: Pelusios castanoides castanoides Hewitt, 1931 and Pelusios subniger Bonnaterre, 1789 (present study); Pelusios upembae Broadley, 1981 , Pelusios bechuanicus Fitzsimons, 1932 , and Pelusios rhodesianus Hewitt, 1927 ( Dvořáková et al. 2015).

Type material: No type material was designated by Dias (1951) in the original description of T. neitzi . The hapantotype, blood smear KO-7-12 from the host Pelusios upembae , was deposited by Dvořáková et al. (2015) in the collection of the Department of Biology and Wildlife Diseases , University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic .

Material in this study: Three peripheral blood smears from the host Pelusios c. castanoides and two peripheral blood smears from the host Pelusios subniger deposited in the Parasitic Worm Collection, National Museum, Bloemfontein, South Africa, with accession numbers NMB P 1023 (RE210314A5), NMB P 1021 (RE210313C1), NMB P 1022 (RE210314A3), NMB P 1029 (RL200227A1), and NMB P 1028 (RL200227A2).

Type locality: Near Maputo River, Catuane region, Maputo, Mozambique ( Dias 1951) .

Additional localities: Save River valley, Mozambique ( Pienaar 1962). Luena vicinity, Bukama region, Democratic Republic of the Congo; Catabola, Bié, Angola; Guija, Gaza, Mozambique;

and Democratic Republic of the Congo (unspecified) ( Dvořáková et al. 2015).

Localitiesinthisstudy: ZimambeniPan(27°02 ʹ 21.8″ S, 32°28 ʹ 54.8″ E) GoogleMaps and near Vukuzani Pan (27°00 ʹ 23.5″ S, 32°26 ʹ 00.3″ E), Tembe Elephant Park , KwaZulu-Natal, South Africa GoogleMaps . Mbancane Pan (24°17 ʹ 04.8″ S, 32°16 ʹ 35.6″ E), Karingani Game Reserve , Maputo, Mozambique GoogleMaps .

Site of infection: Peripheral blood.

Vector: Unknown.

Stages in vector: Unknown.

Representative DNA sequence: The sequence data specifically associated with T. neitzi (upon which the present biological description is based) have been submitted to GenBank and are as follows: nuclear 18S rDNA (nu 18S) partial sequence PP826323 (RE210314A5), PP826325 (RE210313C1), PP826324 (RE210314A3), PP826321 (RL200227A1), and PP826322 (RL200227A2).

Description: Measurement range shown in micrometres (mean ± SD). Body length 43.66–53.06 (49.08 ± 2.87) (N = 24) and body width 4.47–8.95 (5.59 ± 1.38) (N = 24); with a body shape index of 5.49–11.48 (9.16 ± 1.73) (N = 24). Nucleus length 3.18–4.96 (4.05 ± 0.44) (N = 24) and nucleus width 2.12–4.21 (2.87 ± 0.56) (N = 24); with a nuclear index of 1.05–1.73 (1.44 ± 0.18) (N = 24). Undulating membrane width 1.12–2.53 (1.91 ± 0.36) (N = 24) and number of undulations 9–14 (10.63 ± 1.3) (N = 24). Kinetoplast length 0.76–1.08 (0.92 ± 0.11) (N = 24) and kinetoplast width 0.32– 0.67 (0.52 ± 0.1) (N = 24). Mid-nucleus to anterior body end distance 20.55–31.94 (27.4 ± 3.25) (N = 24) and mid-nucleus to posterior body end distance 18.24–25.14 (22.28 ± 1.66) (N = 24). Kinetoplast to anterior body end distance 39.79–48.88 (45.18 ± 2.89) (N = 24) and kinetoplast to posterior body end distance 2.35–6.71 (3.99 ± 1.04) (N = 24). Kinetoplast to mid-nucleus distance 15.53–20.27 (18.17 ± 1.2) (N = 24). Free flagellum length 10.42–17.09 (13.54 ± 3.36) (N = 4). The nucleus and kinetoplast are positioned 46.78–64.89 (55.71 ± 4.59)% (N = 24) and 85.01–98.48 (92.07 ± 3.36)% (N = 24) from the anterior body end, respectively.

Remarks: A single broad morphotype ( Fig. 1A–E View Figure 1 ) was detected, with no dividing forms. The mean morphometric measurements of the broad morphotype trypomastigote forms observed infecting both Pelusios c. castanoides and Pelusios subniger hosts were within 2.5 µm difference. Thus, these values were combined, because we believe it is the same species infecting both hosts, which is supported by the identical genotype data. A small number of slender trypomastigote forms (see Fig. 1F View Figure 1 ) were observed in a single host specimen, NMB P 1022 (RE210314A3), alongside the commonly observed broad trypomastigote forms, but their morphometrics were not combined in the present study. The body of the commonly observed broad form was relatively broad and elongate, with striations occasionally visible ( Fig. 1B, C, E View Figure 1 ).

The commonly observed broad forms of this parasite conform closest morphologically to T.neitzi Dias,1951 and T.mocambicum Pienaar, 1962 (see Supporting Information, Table S2). The trypanosome from the present study is described from the turtle, Pelusios castanoides , a sister species within the same genus as the type host of both T. neitzi Dias, 1951 and T. mocambicum Pienaar, 1962 , Pelusios sinuatus (syn. Pelusios s. zuluensis and Pelusios s. sinuatus ). Given that the species description by Pienaar (1962) did not designate any type material and the morphological data could be considered inadequate, a redescription was provided by Dvořáková et al. (2015). However, Pienaar (1962) discloses in a footnote of his thesis only learning of the existence of Dias’ (1951) work after the completion of his own report and personally states that T. mocambicum is likely to be synonymous with one of the species described by Dias (1951).

The average body dimensions of the broad forms in the present study (49.08 ± 2.87 by 5.59 ± 1.38 µm) are within the morphometric ranges of 39.9–52.0 by 3.6–5.7 µm, for the original description of T. neitzi (see Dias 1951). These dimensions also corresponded to the morphometrics in the redescription of T. mocambicum , 52.3 ± 3.3 by 5.4 ± 0.9 µm ( Dvořáková et al. 2015), in addition to the ‘short’ forms in the original description by Pienaar (1962), 50–55 by 5–6 µm. Although Dias (1951) used a slightly different system of measuring the nucleus dimensions of T. neitzi in comparison to the present study, in which the nucleus was measured from the anterior to posterior, instead of the maximum length, the measurements are still comparable owing to the rounded shape of the nucleus. In the present study, the nucleus of the broad form measured 4.05 ± 0.44 by 2.87 ± 0.56 µm, which was near the upper range described by Dias (1951) for T. neitzi , of 3.1–3.9 by 1.8–2.6 µm. A nucleus of similar size was present in the redescription of T. mocambicum , measuring 3.8 ± 0.7 by 3.1 ± 0.4 µm ( Dvořáková et al. 2015). Pienaar (1962) was unable to determine the nucleus size in the original description of T. mocambicum . The mid-nucleus to posterior end distances of the trypanosome infection from the present study and original description of T. neitzi were consistent, measuring 22.28 ± 1.66 and 22.45–23.65 µm, respectively. These distances were within the range of 23–28 µm for T. mocambicum , derived from the redescription by Dvořáková et al. (2015). A slightly shorter kinetoplast to posterior end distance of 0.7–1.0 µm was originally described for T. neitzi , in contrast to 3.99 ± 1.04 µm in the present study. This distance was close to that of the redescription of T. mocambicum , 3.9 ± 0.7 µm ( Dvořáková et al. 2015). A prominent undulating membrane and long flagellum are commonly described in the present study and for T. neitzi and T. mocambicum .

Furthermore, the trypanosome from the present study resembles the trypanosomes in the plates of Dias (1951), Pienaar (1962), and Dvořáková et al. (2015), although Pienaar (1962) does not indicate whether the specimens of T. mocambicum in his photographic plates are large, intermediate, or short forms and does not provide a scale of the image. The present study and the studies by Dias (1951), Pienaar (1962), and Dvořáková et al. (2015) used similar Romanowsky–Giemsa-type stains. Therefore, we agree with the assumption of Dvořáková et al. (2015) that the reason for the darker, basophilic properties of Pienaar’s (1962) description could be attributable to longer staining durations. However, Pienaar (1962) does not specify the staining time.

The small number of slender trypanosomes observed in the present study were smaller and narrower, and their nucleus was positioned more towards the posterior than in the commonly observed broad forms. Slender forms described by Dvořáková et al. (2015) have a broader posterior and taper towards the anterior, whereas the slender forms from the present study are more transversely symmetrical in shape. Given that these slender forms were not observed in any of the other hosts infected with the commonly observed broad form in the present study, and because reptile trypanosomes generally have only a single trypomastigote form in the vertebrate host ( Telford 2009), they could subsequently not be classified as the same species and are suspected to be a mixed infection. Furthermore, the slender forms observed by Dvořáková et al. (2015) could not be assigned to a species, because all the samples were confirmed to be mixed infections with T. neitzi (syn. T. mocambicum ). Therefore, further investigation is needed to determine whether they are indeed a separate species or are a different morphotype of the same species, because the number of slender forms found was too small for accurate morphometric comparisons.

The hosts of the trypanosome from the present study were collected from water pans in Tembe Elephant Park, northern KwaZulu-Natal, South Africa, and Karingani Game Reserve , Maputo, south-western Mozambique, which are supplied by tributaries of the Maputo River and Limpopo River , respectively. The type host of T. neitzi was collected by Dias (1951) near Catuane, Mozambique from the Maputo River, which borders South Africa and Mozambique. In the original description of T. mocambicum , the type host was collected in the Save River valley , Mozambique ( Pienaar 1962). Although Dvořáková et al. (2015) redesignated the type locality in the redescription of T. mocambicum as a locality in the Democratic Republic of the Congo, T. mocambicum was also reported in their study from the town of Guija , near the Limpopo River in southern Mozambique. The aforementioned localities (excluding the Democratic Republic of the Congo) are all situated within the same river basin in southern Mozambique and north-eastern South Africa, and are geographically connected by a network of river systems supplied by tributaries of the Save River , Limpopo River , Komati River , and Mbuluzi River ( Bullock and Hülsmann 2015). African pelomedusid turtles are known to migrate great distances over land, in addition to being proficient swimmers ( Branch 2012, Vamberger et al. 2019, Price et al. 2022). Thus, it is conceivable that their parasites would be spread throughout the river basin and surrounding areas, because infected individuals travel diligently within their habitat range, transmitting their accompanying parasites throughout their journey as they are fed upon by invertebrate vectors.

For the above reasons, T. neitzi Dias, 1951 and T. mocambicum Pienaar, 1962 emend. Dvořáková & Široký , are shown to be synonymous, and the species name Trypanosoma neitzi Dias, 1951 takes priority according to the Principle of Priority in Article 23.1 of the ICZN code, because it is the oldest name first used to describe this organism. Thus, Trypanosoma mocambicum Pienaar, 1962 emend. Dvořáková & Široký is designated as a junior synonym of Trypanosoma neitzi Dias, 1951 . Subsequently, the commonly observed broad trypanosome from the present study is classified as Trypanosoma (Haematomonas) neitzi , because it conforms to the original descriptions of T. neitzi Dias, 1951 and T. mocambicum Pienaar, 1962 , and redescription of T. mocambicum by Dvořáková et al. (2015). No type material was designated by Dias (1951) in the original description of T. neitzi . The present study provides additional voucher material from the same region and river system as the original descriptions T. neitzi and T. mocambicum .