Kontrimavichusia testiculata, Makarikov & Stakheev, 2024

Makarikov, Arseny A. & Stakheev, Valeriy V., 2024, New species of Kontrimavichusia Makarikov & Binkienė, 2022 (Eucestoda: Hymenolepididae) from arvicoline rodents (Rodentia: Cricetidae) from the North Caucasus, European Journal of Taxonomy 947, pp. 268-288 : 271-275

Kontrimavichusia testiculata sp. nov.

urn:lsid:zoobank.org:act:3CC2D714-6E24-4D8C-8B75-D8AC8D6178AA

Figs 1–2 , 5–6 , Tables 1–2

Diagnosis

Kontrimavichusia testiculata sp.nov. has morphological characters typical of the genus Kontrimavichusia , namely rhynchus armed with cricetoid-like hooks, apex of rostellum invaginable and blades of retracted hooks directed anteriorly, suckers armed with minute spines, ventral canals connected by irregularly spaced transverse anastomoses, copulatory part of vagina surrounded by circular musculature and covered externally by dense layer of intensely-stained cells, labyrinthine uterus extending beyond osmoregulatory canals into both lateral fields, situated dorsally to osmoregulatory canals and genital ducts and embryophore without polar filaments ( Makarikov & Binkienė 2022).

Etymology

This specific epithet refers to the very distinctive morphological feature of the species, namely its relatively great number of testes.

Type material

Holotype

RUSSIA • Republic of Adygeya, Maykopsky District, suburbs of Nikel ; 44º10′31″ N, 40º09′24″ E; 7 Jul. 2014; A.A. Makarikov leg.; ISEA AM14-134#1 (ex 253).

Paratypes

RUSSIA • 1 spec.; same data as for holotype; ISEA AM14-134#2 (ex 254) • 1 spec.; same data as for holotype; ISEA AM14-142#1 (ex 293) • 1 spec.; same data as for holotype; ISEA AM14-142#2 (ex 294) • 1 spec.; same data as for holotype; ISEA AM14-147#1 (ex 250) • 1 spec.; same data as for holotype; ISEA AM14-147#2 (ex 251) • 1spec.; same data as for holotype; 4 Jul. 2014; ISEA AM14-72#1 • 1 spec.; same data as for holotype; ISEA AM14-72#2 (ex 325) • 1 spec.; same data as for holotype; ISEA AM14- 72#3 (ex 326) • 1 spec.; same data as for holotype; 6 Jul. 2014; ISEA AM14-110#1 (ex 328) • 1 spec.; same data as for holotype; ISEA AM14-127#1 • 1 spec.; same data as for holotype; 10 Jul. 2014; ISEA AM14-178#3 (ex 261) • 1 spec.; same data as for holotype; 13 Jul. 2014; ISEA AM14-217#1 .

Other material examined

RUSSIA • 1 spec.; Karachay-Cherkess Republic, suburbs of Teberda; 43º27′21″ N, 41º47′44″ E; 11 Sep. 2016; A.A. Makarikov leg.; ISEA AM16-403#1 (ex 341) • 1 spec.; same data as for preceding; ISEA AM16-403#2 (ex 342) • 1 spec.; same data as for preceding; ISEA AM16-403#3 (ex 343) .

Type host

Microtus majori (Thomas, 1906) ( Rodentia : Cricetidae : Arvicoline).

Description ( Figs 1–2 )

[Based on 8 stained and mounted specimens and 9 scolices mounted in Berlese’s medium.] Fully developed strobila 72–128 (101; n = 6) mm long, with maximum width 2.6–3.4 (3.0; n = 6) mm at level gravid proglottides. Strobila flat, consisting of 410–530 craspedote proglottides. Scolex slightly compressed dorso-ventrally, 324–412 wide (374; n = 3), not clearly distinct from neck. Suckers small, thick-walled, rounded or oval, cup-shaped, 160–181 × 120–170 (171 × 144; n = 12), usually reaching lateral margins of scolex, armed with minute (less than 1 long) spines; spines covering entire sucker surface ( Fig. 1A–B ). Rostellar pouch 160–195 × 115–142 (175 × 128; n = 3), with muscular walls, its bottom not reaching level of posterior margin of suckers. Rostellum 115–153 × 50–88 (134 × 67; n = 3), sac-like, muscular, apex invaginable; when rostellar apparatus retracted, rostellar hooks with blades directed anteriorly ( Fig. 1B ). Rhynchus 80–102 long and 55–78 wide, with well-developed circular musculature, armed with single crown of 20–28 (n = 8) rostellar hooks of cricetoid-like type ( Fig. 1C ). Rostellar hooks with relatively short handle and straight blade; axis of blade situated to axis of guard at acute angle; guard narrow in anterior surface; handle and blade slightly shorter or equal in length with guard. Hook measurements: total length 17.5–22 (19.7; n = 28), handle 6.3–9 (7.6; n = 28), blade 6.3–9 (7.6; n = 28) and guard 8–10.5 (9.4; n = 28). Neck 300–360 wide (n = 3), approximately equal in width with scolex ( Fig. 1A–B ).

Ventral osmoregulatory canals 75–155 (110; n = 35) wide, connected by irregularly spaced transverse anastomoses (present in up to 54% proglottides) ( Fig. 1D–E ). Dorsal osmoregulatory canals very thin, 6–13 (9; n = 35) wide at level of hermaphroditic proglottides, usually situated directly dorsal (not shifted left or right) to ventral canals. Genital pores unilateral, dextral ( Fig. 1D–E ). Genital ducts pass dorsally to both ventral and dorsal longitudinal osmoregulatory canals. Development of proglottides gradual, protandrous.

Mature proglottides 210–280 × 1400–1780 (247 × 1612; n = 24), transversely elongate, trapezoid ( Fig. 1D–E ). Testes relatively large, almost equal in size, 145–210 × 125–175 (175 × 149; n = 40), round or oval, 4-6 in number (usually 5, 68.8%; n = 207), poral testes 1–3 (usually 2, 54.6% or 1, 44.9%; n = 207) separated from 2–5 (usually 3, 52.2% or 4, 34.3%; n = 207) antiporal testes by female gonads. Poral testes situated posteriorly, 2–3 antiporal testes testes most often situated posteriorly and 1–2 anteriorly. Cirrus-sac relatively short, with thick muscular walls, club-shaped, 370–445 × 55–77 (401 × 67; n = 31). Antiporal part of cirrus-sac substantially crossing poral ventral longitudinal canal ( Fig. 1E–F ). Genital atrium simple, cup-shaped, opens laterally, approximately in middle of lateral proglottis margin. Cirrus large, 152–200 × 30–42 (175 × 36; n = 28), cylindrical, armed with very small (up to 1.0–1.5 long), needle-shaped spines ( Fig. 2A ). Internal seminal vesicle with circular musculature, ovoid, 175–240 × 50–72 (212 × 61; n = 28), occupying half of cirrus-sac length ( Fig. 1E–F ). External seminal vesicle, 120–280 × 70–135 (185 × 101; n = 25), round or oval, clearly distinguishable from vas deferens, normally smaller than seminal receptacle.

Ovary 380–530 (455; n = 30) wide, median, transversely elongate, fan-shaped, irregularly lobed, ventral to male genital organs, occupying less than half of median field, overlapping testes ( Fig. 1E ). Vitellarium 85–115 × 180–275 (100 × 215; n = 30), postovarian, slightly shifted to lateral side of proglottis, slightly lobed. Vagina tubular, clearly distinct from seminal receptacle; ventral to cirrus-sac. Copulatory part of vagina 120–165 × 10–35 (145 × 18; n = 25), shorter than cirrus-sac, thick-walled, surrounded by circular musculature and covered externally by dense layer of intensely stained cells; proximal part of vagina infundibular ( Figs 1F , 2A ). Conductive part of vagina indistinct. Seminal receptacle relatively large, transversely elongate, 375–550 × 80–110 (488 × 92; n = 20).

Uterus appears as perforated, transversely-elongate band, situated dorsally to testes, genital ducts and osmoregulatory canals and extending laterally beyond longitudinal osmoregulatory canals. With proglottis development, uterus forms numerous diverticula on ventral side and becomes labyrinthine in terminal postmature proglottides. Testes persist in postmature proglottides; cirrus-sac and vagina persist in gravid proglottides ( Fig. 2B ). Gravid proglottides transversely elongate, 410–550 × 2650–3450 (504 × 2042; n = 20). Fully developed uterus labyrinthine, occupying entire median field, extending bilaterally, dorsally, beyond longitudinal osmoregulatory canals ( Fig. 2C ). Uterus contains numerous (up to 1800–2500) small eggs. Eggs 55–61 × 63–70, subspherical, with very thin outer coat (up to 0.5–0.8 thick); oncospheres 22–26 × 30–33 ( Fig. 2D ). Embryophores very thin, 27–32 × 35–38, without polar filaments. Embryonic hooks small, antero-lateral hooks (10.3–10.6), much more robust than slender postero-lateral (10.0–10.5) and median (11.0–11.5) hooks ( Fig. 2E ).

Distribution

Russia (Republic of Adygeya, Karachay-Cherkess Republic).

Remarks

Until the present study, K. asymmetrica was the only known representative of the genus Kontrimavichusia . Kontrimavichusia testiculata sp. nov. is readily distinguishable from the type species by the number of testes; the former species has 4–6 testes per proglottis while in K. asymmetrica those are usually 3. The cirrus-sac in K. testiculata substantially crosses the poral osmoregulatory canals, whereas the cirrus-sac of K. asymmetrica overlaps or rarely crosses the ventral longitudinal canal. Further, the distal end of the rostellar pouch does not attain the level of the posterior margins of suckers; in K. asymmetrica the rostellar pouch reaches to or slightly extends beyond the level of the posterior margins of the suckers. In addition, specimens of K. testiculata are characterized by larger suckers and a longer cirrus and cirrus-sac relative to K. asymmetrica ( Table 1 ).

Figures

Fig. 1. Kontrimavichusia testiculata sp. nov. A. Holotype (ISEA AM14-134#1), scolex, dorso-ventral view. B. Paratype (ISEA AM14-147#2), scolex, sub-lateral view. C. Paratype (ISEA AM14-142#2), rostellar hooks in profile and frontal view (note narrow hook guard). D. Holotype, male mature proglottides, dorsal view.E. Holotype, hermaphroditic mature proglottis, dorsal view.F. Paratype (ISEA AM14-147#2), genital ducts, dorsal view. Scale bars: A–B, F = 100 µm; C = 10 µm; D–E = 300 µm.

Fig. 2. Kontrimavichusia testiculata sp. nov.A. Paratype (ISEAAM14-147#2), cirrus and vagina, ventral view. B. Holotype (ISEAAM14-134#1), pregravid proglottis, showing appearance of uterine diverticula, dorsal view. C. Holotype, gravid proglottis, showing labyrinthine uterus, dorsal view. D. Holotype, egg. E. Holotype, embryonic hooks. Abbreviations: al = anterolateral; m = median; pl = postero-lateral. Scale bars: A = 50 µm; B–C = 300 µm; D = 20 µm; E = 10 µm.

Fig. 5. Maximum likelihood phylogenetic tree of Kontrimavichusia Makarikov & Binkienė, 2022 and Hymenolepis Weinland, 1858 based on analysis of partial sequences of the 28S rRNA gene. Bootstrap support given for maximum likelihood analysis based on 1000 replicates. Bootstrap support values lower than 70% are not shown.

Fig. 6. Maximum likelihood phylogenetic tree of species of Kontrimavichusia Makarikov & Binkienė, 2022 based on analysis of partial sequences of the nad1 gen. Bootstrap support given for maximum likelihood analysis based on 1000 replicates. Bootstrap support values lower than 70% are not shown.