Douthittia

Haukisalmi, Voitto, Hardman, Lotta M., Hoberg, Eric P. & Henttonen, Heikki, 2014, Phylogenetic relationships and taxonomic revision of Paranoplocephala Lühe, 1910 sensu lato (Cestoda, Cyclophyllidea, Anoplocephalidae), Zootaxa 3873 (4), pp. 371-415 : 393-394

Douthittia n. g.

( Fig. 16 )

Etymology. The name of the new genus refers to Herman Douthitt, a pioneer in the taxonomy of anoplocephalid cestodes of rodents. “ Douthittia ” is feminine.

Diagnosis. Strobila long or of moderate length, relatively narrow. Scolex merging gradually with neck. Suckers embedded within scolex or slightly protruding, directed laterally or antero-laterally. Minimum neck width roughly half of scolex width (usually less in D. nordenskioeldi ). Proglottids slightly or distinctly craspedote. Genital pores unilateral or infrequently (and irregularly) alternating. Genital ducts pass dorsal to longitudinal osmoregulatory canals. Testes mostly anterior to ovary, significantly overlapping latter and being often in contact with vitellarium. Antiporal testes overlap or extend slightly across antiporal ventral longitudinal canal, poral testes usually reaching corresponding poral canal (except in D. bairdi ), but not overlapping it. Cirrus-sac rather wide, overlapping or extending across poral longitudinal canals. Vagina covered with distinct cell-layer; vagina and vaginal tube widening distally. Vagina slightly shorter than or as long as cirrus sac, position with respect to ventral longitudinal canal variable. Seminal receptacle spherical or subspherical, relatively small. Ovary median, large relative to proglottid size, usually filling whole space between ventral longitudinal canals. Vitellarium median or poral with respect to ovary. Early uterus anterior, ventral to other organs, extending laterally beyond longitudinal canals; lateral parts usually slightly widened posteriorly; reticulations relatively dense. In cricetid ( Arvicolinae , Neotominae ) and sciurid rodents in North America and Arctic Eurasia.

Type species: D. nearctica (Haukisalmi & Henttonen, 2007) n. comb. Paranoplocephala nearctica Haukisalmi & Henttonen, 2007 Other species:

D. bairdi ( Schad, 1954) n. comb.

Andrya bairdi Schad, 1954

Paranoplocephala bairdi Schad, 1954 Tenora, Murai & Vaucher, 1984 D. nordenskioeldi n. comb.

Paranoplocephala nordenskioeldi Haukisalmi, Wickström, Hantula & Henttonen, 2001 Paranoplocephala alaskensis Haukisalmi & Henttonen, 2007 n. syn. D. primordialis ( Douthitt, 1915) n. comb.

Andrya primordialis Douthitt, 1915

Paranoplocephala primordialis ( Douthitt, 1915) Tenora, Murai & Vaucher, 1986

Holotype of D. nearctica : MSB Endo 1 (included in the present phylogenetic analysis).

Remarks. Douthittia resembles Eurotaenia , Arctocestus , Rauschoides and Lemminia in having a narrow neck and long vagina (relative to the length of the cirrus sac) and ovoid/pyriform (not elongated) seminal receptacle. Douthittia differs from Arctocestus and Lemminia by its more extensive distribution of testes in the poral part of the proglottid, and from Arctocestus and Rauschoides by its less numerous testes lateral to the antiporal ventral canal. Douthittia can be distinguished from Eurotaenia by the serrated, distinctly craspedote proglottids and prominently elongated anterior strobila (when fully relaxed) in the latter. For additional differences between Douthittia and Lemminia , see Remarks section for the latter genus.

Douthittia nearctica , D. nordenskioeldi and P. alaskensis consistently formed a strongly supported clade in the present mitochondrial data sets. In nad1 data, these three species formed an unresolved clade with very low genetic divergence, suggesting that they all might be conspecific. However, cox1 data and concatenated data suggested that D. nearctica and D. nordenskioeldi + P. alaskensis represent separate sister species with distinct genetic divergence. As D. nordenskioeldi and P. alaskensis also show considerable overlap in their morphological features, P. alaskensis becomes a synonym of D. nordenskioeldi . Douthittia nearctica is retained as a valid species because of its phylogenetic and morphological distinction from D. nordenskioeldi and P. alaskensis (see Haukisalmi & Henttonen 2007).

Douthittia spp. are part of a larger clade, which also includes an undescribed, basal species of Douthittia , Diandrya composita (cox1 data) and Beringitaenia nanushukensis n. sp. The phylogenetic association between Diandrya , D. nordenskioeldi and P. alaskensis (the latter then as P. primordialis ) has been suggested earlier by the concatenated 28S+ITS1+ cox1 data of Wickström et al. (2005). The basal Douthittia sp. from Myodes rutilus from British Columbia ( Canada) was not described as new because of its morphological similarity with other Douthittia species, especially D. nearctica .

As yet, there are no molecular data for D. primordialis and D. bairdi .

Figures

FIGURE 16. Douthittia nearctica from Myodes rutilus from Alaska (USA). A. Scolex and neck. B. Mature proglottid (redrawn from Haukisalmi & Henttonen 2007).