Skrjabinotaenia (Meggittina) cf. baeri ( Lynsdale, 1953 ) Tenora, 1964

Skrjabinotaenia (Meggittina) cf. baeri ( Lynsdale, 1953) Tenora, 1964

( Fig. 5 View FIGURE 5 )

Material examined: Five specimens from Rhabdomys pumilio (Sparman) and R. dilectus De Winton ( Murinae ) from South Africa, reported originally as M. baeri (see Spickett et al. 2017a; Haukisalmi et al. 2018). For the distribution and prevalence of S. (M.) cf. baeri in South Africa, see Spickett et al. (2019).

Deposited voucher specimens: FMNH: KN.3654, KN.47856, KN.47857, KN.7143 (slides), KN.3653 (ethanol) .

Deposited DNA sequences: GenBank: MG050013 View Materials - MG050015 View Materials (nuclear 28S gene), MG049964, MG049965 (mitochondrial 12S-16S region) ( Haukisalmi et al. 2018) .

Description: Strobila transversely elongate, gravid specimens consisting of 3–4 proglottids. Length of pregravid strobila 1.2–1.6 (n=4) mm and width up to 14 mm; fully gravid (detached) proglottids 1.9–2.0 mm (n=3) long and 13–17 mm wide (n=3). Lateral proglottid margins convex; margins between proglottids concave. “Posterior” margins of pregravid and gravid proglottids slightly fringed. Scolex embedded in anterior strobila, in one case with rudimentary “apical organ” (diameter 36). Diameter of suckers 94–112 (x̅=104, n=10). Genital pores regularly alternating, positioned near anterior margin of proglottid. Osmoregulatory system consists of multiple longitudinal narrow anastomosing canals.

Testes 170–190 (n=2) in total number, positioned as two widely separate lateral groups. Testes more numerous on antiporal side (110–147, x̅=127, n=5) than on poral side (62–98, x̅=77, n=3). Cirrus sac slender, 142–238 (x̅=185, n=7) long and 32–44 (x̅=36, n=6) wide, slightly curved, sometimes poorly delimited from vas deferens. Distinct internal seminal vesicle absent. Distal vas deferens coiled; external seminal vesicle lacking.

Ovary median, massive, 1.4–2.0 mm (n=3) wide, lobulate, slightly branched; consisting of two main lobes; antiporal lobe more extensive than poral one; poral lobe extending to lateral margin of vitellarium and antiporal lobe maximally extending near lateral margin of testicular field; prominent unbranched antero-poral lobe extending anterior to median lobe of vitellarium. Vitellarium elongate, 501–707 (x̅=612, n=5) long and 137–263 (x̅ =190, n=5) wide, bilobed; lateral lobe significantly larger than median lobe and usually consisting of 3–4 short lateral lobules. Mehlis’ gland spherical, ca. 100 in diameter, positioned between seminal receptacle and antero-poral lobe of ovary, sometimes overlapping latter. Vagina long (425–965, x̅=707, n=7) and slender, of uniform width, curved distally following outline of cirrus sac, opens posterior to male pore; vagina 2.5–5.1 (x̅=3.8, n=7) times longer than cirrus sac. Seminal receptacle ovoid or ellipsoidal, 100–186 (x̅=131, n=8) in larger diameter, positioned slightly medial to midline of vitellarium.

Uterus with very short anterior stem and distinct anterior appendage, and 2–3 primary branches on each side, which give off numerous short secondary branches primarily from “posterior” side. “Posterior” primary branch very prominent compared with “anterior” primary branch/branches. Eggs elongate (collapsed), 27–37 in length; embryophore elongate, 15–21 in length and 7–11 in width.

Remarks. The present material appears to resemble closely the type material of S. (M). baeri , but they may be separated by the number of testes (170–190 vs. 250–350), and absolutely (425–965 vs. 390–400) and relatively longer vagina (2.5–5.1 vs. 1.3 times longer than the cirrus sac) in the present specimens. The absolute length of the vagina, and possibly also the number of testes, may be affected by the size of the proglottid, but the relative length of the vagina should be size-independent and therefore a taxonomically more reliable feature.

Conspecificity of four specimens of S. (M). cf. baeri from Rhabdomys spp. and their high genetic divergence with respect to the other lineages in the African clade was confirmed by phylogenetic analyses based on the nuclear (28S) and mitochondrial (12S-16S) DNA regions ( Haukisalmi et al. 2018). Spickett et al. (2019) performed on extensive analysis of helminth parasitism of 13 species of rodents, including murids ( Murinae , Gerbillinae ) and nesomyids ( Cricetomyinae ), throughout South Africa, and showed that S. (M). cf. baeri is strictly a parasite of Rhabdomys spp.

Although the present specimens show certain morphologic differentiation from S. (M). baeri , the latter has been too poorly described for a reliable separation of these materials. A detailed redescription of the type material of S. (M). baeri would be necessary for a revision of the S. (M.) baeri -like forms, including those from the Central African Republic ( Quentin 1971) and Madagascar ( Quentin & Durette-Desset 1974, Haukisalmi et al. 2010, 2018) ( Table 1 View TABLE 1 ).