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Franzese, Sebastián, Mutti, Leonardo D., Tropea, Carolina & Ivanov, Verónica A., 2022, Morphological study of members of the genus Echeneibothrium (Cestoda: Rhinebothriidea: Echeneibothriidae) from rajiform skates of the Argentine Sea and analysis of the phylogenetic relationships within the family Echeneibothriidae, Zoologischer Anzeiger 299, pp. 1-20 : 5-7

Site of infection: Spiral intestine.

Type material: Holotype MACN-Pa No. 734 (whole mature worm), 28 paratypes MACN-Pa No. 735/1–5, 736/1–23 (25 whole mature worms, and histological sections of 1 mature proglottid and 2 scoleces).

Prevalence of infection: 40% (2 hosts infected out of 5 examined).

Etymology: This species is named after Cristina E. Fernandez de Kirchner, former president and current vice president of Argentina, for promoting scientific and technological development as a key step towards the construction of a free and sovereign country.

3.1.3. Remarks

The morphology of the specimens collected from B. cousseauae is consistent with the diagnosis of the genus Echeneibothrium in a highly developed retractile apical myzorhynchus in the adult scolex and four stalked facially loculated bothridia ( Euzet 1994). Echeneibothrium cristinae sp. nov. is most similar to a single species of Echeneibothrium , E. pollonae , from which differs by having longer bothridial stalks (220–400 vs. 150), a cirrus sac mostly occupying the lateral half of the proglottid rather than the middle region of the proglottid, a vas deferens not reaching the ovary, and vitelline follicles extending posterior to the ovary.

The new species can be distinguished from each of its 23 remaining congeners based on unique combinations of characters. Echeneibothrium cristinae sp. nov. is shorter than Echeneibothrium beauchampi Euzet, 1959 , Echeneibothrium dubium van Beneden, 1861 , Echeneibothrium fallax ( van Beneden, 1871) , Echeneibothrium julievansium Woodland, 1927 , Echeneibothrium macrascum Riser, 1955 , Echeneibothrium megalosoma Carvajal & Dailey, 1975 and Echeneibothrium vernetae Euzet, 1956 (4.7–13.6 mm vs. 50–70 mm, 15–20 mm, 60 mm or more, 55 mm, 30 mm, 91–220 mm and 100 mm, respectively). In addition, the new species is easily distinguishable from Echeneibothrium bathyphilum Campbell, 1975 , Echeneibothrium elongatum Williams, 1966 and E. variabile by its lower number of proglottids (41–73 vs. 78–208, 350 or more and 100–150, respectively), and from Echeneibothrium dolichoophorum Riser, 1955 , Echeneibothrium minutum Williams, 1966 , E. multiloculatum and Echeneibothrium octorchis Riser, 1955 by its greater number of proglottids (41–73 vs. 35, 8–10, 11–27 and 25, respectively).

Echeneibothrium cristinae sp. nov. has fewer loculi on the distal bothridial surface than E. algeriensis , E. beauchampi , Echeneibothrium demeusiae Euzet, 1959 , Echeneibothrium faxanum Manger, 1972 , Echeneibothrium maculatum Woodland, 1927 , E. minutum and E. variabile (10–12 vs. 28–30, 14, 18, 14, 15–17, 20 and 16, respectively), and more loculi than E. bathyphilum , E. elongatum , E. megalosoma , Echeneibothrium sobrinum Campbell, 1975 and E. vernetae (10–12 vs. 8, 6, 8, 5 and 8, respectively). It also differs from Echeneibothrium myzorhynchum Hart, 1936 , E. sobrinum and E. williamsi in having a medial longitudinal septum on the distal bothridial surface.

The cirrus sac of the new species is longer than in Echeneibothrium canadensis Keeling & Burt, 1996 , E. maculatum and E. octorchis (193–250 vs. 132–172, 186 and 87–111, respectively), wider than in E. bathyphilum , E. canadensis and E. octorchis (100–133 vs. 40–90, 49–74 and 51–66, respectively), and narrower than in E. dolichoophorum and

E. elongatum (100–133 vs. 270–630 and 230, respectively). The location of the vas deferens entrance into the cirrus sac distinguishes the new species from E. dubium , while the position of the ovarian isthmus and the course of the vagina at the level of the cirrus sac distinguish it from Echeneibothrium abyssorum Campbell, 1977 and E. faxanum .

The new species is the first reported species in the Echeneibothriidae with cilia present on the scolex.