Gyrodactylus mediotorus King, Marcogliese, Forest, McLaughlin & Bentzen, 2013

Rahmouni, Chahrazed, Seifertová, Mária, Bean, Megan G. & Šimková, Andrea, 2024, Intraspecific variation in Gyrodactylus mediotorus and G. crysoleucas (Gyrodactylidae) from Nearctic shiners (Leuciscidae): evidence for ongoing speciation, host-switching, and parasite translocation, Parasite (Paris, France) 31 (29), pp. 1-14 : 6

publication ID

https://doi.org/ 10.1051/parasite/2024023

publication LSID

lsid:zoobank.org:pub:A2F025CD-7379-4E84-921B-AC565CD1EAC8

DOI

https://doi.org/10.5281/zenodo.12751540

persistent identifier

https://treatment.plazi.org/id/A4378781-E94C-FFB6-D75C-F971FC7CFA1A

treatment provided by

Felipe

scientific name

Gyrodactylus mediotorus King, Marcogliese, Forest, McLaughlin & Bentzen, 2013
status

 

Gyrodactylus mediotorus King, Marcogliese, Forest, McLaughlin & Bentzen, 2013 View in CoL ( Figures 2A–2D View Figure 2 )

Previous records: spottail shiner, N. hudsonius (type-host), Îles de la Paix, St. Louis Lake (type-locality) and Îles Vert, St. Lawrence Lake, both in Quebec, Canada [ 48]; weed shiner, N. texanus, Lake Onalaska , Upper Mississippi River, Wisconsin, USA [ 56].

Present study: blacktail shiner, C. venusta , West Mud Creek, Neches River ( Figure 2A–2B View Figure 2 ), and sand shiner, N. cf. stramineus ( Guadalupe River), Guadalupe River ( Figure 2C–2D View Figure 2 ), both in Texas, USA.

Site of infection: fins

Prevalence and intensity of infection: for C. venusta , 5.9%, two infected hosts out of 34 investigated, a single Gyrodactylus specimen on each infected host. For N. cf. stramineus ( Guadalupe River), 14.3%, two infected hosts out of 14 investigated, from 1 to 3 Gyrodactylus specimen per infected host.

Voucher: IPCAS M- 794/1-2

Host GenBank accession numbers: cyt- b: PP314044– PP314045 for C. venusta, PP 314046 for N. stramineus

Parasite GenBank accession numbers: 18S rDNA: PP309997; ITS: PP309999

Morphology: Haptor subcircular, anchor base with folds, tips curved outward, total length 59.4 (55.9–62.6; n = 8); shaft slightly bowed, length 42.9 (40–45; n = 8); point curved and elongate, length 21.5 (20.3–22.6; n = 8); root long, length 20.3 (18.3–21.6; n = 8). Ventral bar with prominent blunt lateral processes extending out of bar, total length 33.5 (30.7– 36.9; n = 8), total width 22.4 (20.7–24.8; n = 8), lateral processes length 7.8 (5.5–9.5; n = 8), distance between tips 26.1 (23–29.5; n = 8), median part with a noticeable knob, width 5.5 (4.3–6.9; n = 8), membrane (shield) rectangular with fine longitudinal striations, extending almost 1/2 of length of anchor shaft, length 18.1 (15.6–20.4; n = 8), width at the insertion 15.3 (12.3–17.6; n = 8). Dorsal bar straight with projections near each end, attenuated ends inserted into terminal plates, total length 23.7 (21–26.2; n = 8), width at midpoint 2.6 (1.8–2.9; n = 8). Marginal hooks total length 35.6 (31–38.8; n = 8); sickle foot moderate with downward globose heel, prominent triangular straightforward toe, conspicuous shelf; sickle proper almost as thick as toe base, shaft length 4.9 (4.4–5.4; n = 8); sickle length to shaft attachment 3.2 (2.8–3.7; n = 8); sickle proximal width 3.1 (2.6–3.5; n = 8); sickle distal width 3.4 (2.8–4; n = 8); point relatively thin and slightly curved, length 1.3 (1.1–1.7; n = 8); filament loop extending about 1/3 of handle length, length 8.5 (7.3–9.7; n = 8); handle ending in a noticeable posterior filament, length 30.1 (26.2–34; n = 8). MCO observed in a single Gyrodactylus specimen from N. stramineus cf. ( Guadalupe River) with a single apical prominent spine and a single row of seven spinelets.

Size and shape of the sclerotized structures of G. mediotorus specimens from southeast populations of each of C. venusta and N. cf. stramineus ( Guadalupe River) overlapped. Compared to the type-material [ 48], noticeable intraspecific variability was observed, mainly in terms of the (i) shorter hamuli (55.9–62.6 µm in this study vs. 65.7– 69.7 µm in the original description), and (ii) the shorter ventral bar (30.7–36.9 µm in this study vs. 36.4–41.3 µm in the original description). Although well visible on the photographs, King et al. [ 48] did not mention the presence of a knob in the median part of the ventral bar or a prominent filament attachment posteriorly to the handle of the marginal hooks. The median knob of the ventral bar was later emphasized by Leis et al. [ 56] when reporting a variant of G. mediotorus on N. texanus , whereas the additional filament marking the posterior end of the marginal hooks was not highlighted. The specimens of G. mediotorus studied herein can be compared to the so-farunknown Gyrodactylus sp. C. venusta ” collected recently in Mississippi [ 82] in having a similar haptoral morphotype, but mainly because of the presence of the ventral bar knob and the filament of the marginal hooks. Yet, considerable variation in the size of the ventral bar is observed (30.7–36.9 µm in this study vs. 20.1 µm in [ 82]). Likewise, our specimens of G. mediotorus possessed a longer ventral bar than G. mediotorus from N. texanus (30.7–36.9 µm in this study vs. 22 µm in [ 56]).

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